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> April 29-May 5 Plains/Midwest/OV/GL Tornado Outbreak, Long-range (6-10 days): forecasts and observations
ClicheVortex2014
post May 1 2018, 12:45 AM
Post #41




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HRRR has numerous cells popping, a major one on NE/KS border like has been suggested by NAM for a while.




--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post May 1 2018, 12:57 AM
Post #42




Rank: F5 Superstorm
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Posts: 22,556
Joined: 21-April 14
From: Dayton, Ohio
Member No.: 29,453





Severe threat sounding a bit conditional tomorrow.



QUOTE
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1251 AM CDT TUE MAY 01 2018

VALID 021200Z - 031200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN/CENTRAL PLAINS...

..SUMMARY

SEVERE THUNDERSTORMS ARE EXPECTED ACROSS PARTS OF THE SOUTHERN AND
CENTRAL PLAINS MID-DAY WEDNESDAY THROUGH THE OVERNIGHT. LARGE HAIL,
DAMAGING WINDS, AND A FEW TORNADOES WILL BE POSSIBLE. ISOLATED TO
SCATTERED SEVERE STORMS MAY ALSO DEVELOP ACROSS PARTS OF THE
MIDWEST, WITH HAIL AND DAMAGING WINDS THE PRIMARY THREAT.

..DISCUSSION

THE D2/WEDNESDAY CONVECTIVE OUTLOOK PRESENTS A CHALLENGING FORECAST
SCENARIO, OWING TO THE SUBTLE NATURE OF MULTIPLE IMPULSES ADVANCING
ACROSS THE PLAINS WITHIN A CORRIDOR OF WEAKLY ANTICYCLONIC FLOW.
MOST GUIDANCE INDICATES THIS EVOLUTION WILL RESULT FROM CONTINUED
DIGGING OF THE WESTERN US TROUGH ON TUESDAY, WITH SUBSEQUENT CLOSED
LOW DEVELOPMENT WITHIN THE BROADER TROUGH. IN TURN, RISING HEIGHTS
OVER THE PLAINS SHOULD YIELD WEAK RIDGING ALOFT BY WEDNESDAY
MORNING. AT THE SURFACE, A FRONT IS FORECAST TO EXTEND FROM WESTERN
KANSAS EAST/NORTHEASTWARD TO WISCONSIN, WHILE A DRY LINE WILL BE
POSITIONED FROM THE FRONT IN KANSAS SOUTH/SOUTHWESTWARD INTO WEST
TEXAS.

..SOUTHERN KANSAS TO THE MISSOURI VALLEY

A WEAKENING/VEERING LOW-LEVEL JET IS EXPECTED TO EXTEND ACROSS
EASTERN KANSAS WEDNESDAY MORNING. THROUGH THE LATE MORNING AND
AFTERNOON, THOUGH, LOW-LEVEL FLOW SHOULD BACK SLIGHTLY AHEAD OF A
TRIPLE POINT OVER SOUTHERN KANSAS. IN TURN, INCREASING WARM
ADVECTION AND CONVERGENCE IS EXPECTED TO SUPPORT CONVECTIVE
INITIATION OVER PARTS OF SOUTHERN/CENTRAL KANSAS. MEANWHILE,
SOUTHERLY FLOW WILL TRANSPORT DEW POINTS IN THE MID 60S OVER THE
AREA, SUPPORTING MODERATE MIXED-LAYER BUOYANCY BY AFTERNOON.
ORGANIZED BY SOUTHWESTERLY MID-LEVEL FLOW AROUND 45-55 KT, SEVERAL
CELLS SHOULD BECOME SEVERE, INITIALLY CAPABLE OF LARGE HAIL AND
DAMAGING WINDS.

MODE EVOLUTION (I.E., DISCRETE CELL POTENTIAL) REMAINS QUESTIONABLE
WITH THIS EARLIER CONVECTION, AS THE ORIENTATION OF THE LARGER-SCALE
PATTERN AND RESULTANT VEERED 700MB FLOW MAY ENCOURAGE STRAIGHT
HODOGRAPHS, OR PERHAPS SOME COUNTER-CLOCKWISE CURVATURE IN MID
LEVELS. THEREFORE, STORMS MAY GROW UPSCALE INTO EASTWARD-ADVANCING
LINEAR SEGMENTS, WITH DAMAGING WINDS AS THE PRIMARY THREAT OVER
PARTS OF CENTRAL/EASTERN KANSAS. CONCURRENTLY, ANY HIGHER TORNADO
POTENTIAL MAY NOT INCREASE UNTIL LATE EVENING, AS THE LOW-LEVEL JET
INCREASES, AND CONVECTIVE BANDS POTENTIALLY ACQUIRE EMBEDDED
ROTATING ELEMENTS.

..OKLAHOMA INTO NORTHWEST TEXAS

CONVECTIVE COVERAGE MAY BE SPARSE THROUGH MUCH OF THE DAY, GIVEN
SOMEWHAT VEERED FLOW ALOFT, INCREASED DRYING OVER FAR WESTERN
OKLAHOMA, AND WEAKER CONVERGENCE ALONG THE DRY LINE INITIALLY.
HOWEVER, AS THE LOW-LEVEL JET INTENSIFIES TOWARDS 00Z, A COMBINATION
OF INCREASING LOW-LEVEL SHEAR, A MOISTENING BOUNDARY LAYER, AND
STEEP MID-LEVEL LAPSE RATES WILL YIELD A CONDITIONAL THREAT FOR A
FEW INTENSE STORMS, CAPABLE OF VERY LARGE HAIL, DAMAGING WINDS, AND
TORNADOES. STILL, CONSIDERABLE UNCERTAINTY EXISTS REGARDING THE
POTENTIAL FOR SUSTAINED CONVECTIVE DEVELOPMENT DURING THE EVENING,
OWING TO SOME OF THE ISSUES DESCRIBED ABOVE. MOREOVER, SIMILAR TO
KANSAS, COUNTER-CLOCKWISE HODOGRAPH CURVATURE ALOFT WOULD SUPPORT A
FEW SUSTAINED LEFT SPLITS, INTERFERING WITH THE POTENTIAL FOR
LONGER-TRACKED DISCRETE SUPERCELLS. CONSIDERING THESE CAVEATS, THE
ONGOING ENHANCED IS MAINTAINED WITH MINOR CHANGES.

AS BROADER/STRONGER DEEP ASCENT OVERSPREADS THE PLAINS (AND A
DISTINCT CORRIDOR OF LOW-LEVEL FLOW/MOISTENING ORGANIZES TO THE
WEST), A SEPARATE ROUND OF CONVECTION IS POSSIBLE FROM WEST TEXAS
INTO THE PANHANDLE AND WESTERN OKLAHOMA WEDNESDAY NIGHT. WHILE THE
PARAMETER SPACE MAY REMAIN FAVORABLE FOR TORNADOES AND LARGE HAIL,
CONTINUED DRY AIR ALOFT, QUESTIONABLE MID-LEVEL WIND PROFILES, AND
RELATED MODE ISSUES MAY ALSO YIELD UPSCALE GROWTH INTO
EASTWARD-ACCELERATING BANDS, WITH DAMAGING WINDS AS THE PRIMARY
THREAT.

..MAXIMUM RISK BY HAZARD

TORNADO: 10% SIG - ENHANCED
WIND: 30% - ENHANCED
HAIL: 30% SIG - ENHANCED


--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post May 1 2018, 01:04 AM
Post #43




Rank: F5 Superstorm
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Posts: 22,556
Joined: 21-April 14
From: Dayton, Ohio
Member No.: 29,453





QUOTE(ClicheVortex2014 @ Apr 30 2018, 04:15 PM) *
Looks like there's gonna be multiple areas of significant hail producing supercells today as a part of a severe weather ramp up. Marginal yesterday, slight today, enhanced tomorrow (potential for small moderate IMO near the triple point in KS)... then probably a moderate on Wednesday.

I'm excited to watch the storms on GOES16 over the next few days. This should be the first time we get to watch storms blow up in a strongly unstable (2500-3000 CAPE) atmosphere.



Talk of "explosive development", "discrete storm modes", "strong tornadoes", and a possible upgrade to moderate risk


QUOTE
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT TUE MAY 01 2018

VALID 011200Z - 021200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF CENTRAL KS...SOUTHEAST NE...FAR SOUTHWEST IA...AND FAR NORTHWEST
MO...

..SUMMARY

SEVERE STORMS ARE EXPECTED MAINLY ACROSS NORTH-CENTRAL KANSAS INTO
SOUTHEAST NEBRASKA TUESDAY FROM LATE AFTERNOON THROUGH EVENING.
LARGE HAIL, DAMAGING WINDS, AND A FEW TORNADOES ARE POSSIBLE.

..SYNOPSIS

SHORTWAVE TROUGH CURRENTLY LOCATED APPROXIMATELY 400NM OFF THE
CENTRAL CA COAST IS EXPECTED TO CONTINUE SOUTHWARD TUESDAY MORNING
BEFORE TURNING MORE SOUTHEASTERLY DURING THE AFTERNOON. THE
TRAJECTORY OF THIS SHORTWAVE WILL LEAD TO AN OVERALL DEEPENING OF
THE PARENT UPPER TROUGH, WHICH COVERS MUCH OF THE WESTERN CONUS.
ADDITIONALLY, A MODEST WESTWARD REGRESSION OF THE UPPER TROUGH IS
ANTICIPATED, WHICH WILL SUPPORT BUILDING HEIGHTS ACROSS THE CENTRAL
CONUS.

THE SURFACE PATTERN AT THE BEGINNING OF THE PERIOD WILL LIKELY
FEATURE A LOW CENTERED OVER THE MN ARROWHEAD WITH A COLD FRONT
EXTENDING SOUTHWESTWARD TO ANOTHER LOW OVER NORTH-CENTRAL KS. THIS
FRONTAL ZONE IS NOT EXPECTED TO MOVE MUCH THROUGHOUT THE DAY WITH
THE SECOND LOW DEVELOPING INTO A WELL-DEFINED TRIPLE-POINT BY THE
AFTERNOON. THIS TRIPLE-POINT, AND THE SURFACE FEATURES EXTENDING
FROM IT, WILL SERVE AS THE FOCUS FOR CONVECTIVE DEVELOPMENT LATE
TUESDAY AFTERNOON THROUGH THE EVENING.

..CENTRAL PLAINS INTO THE UPPER MS VALLEY

A SECOND DAY OF MOISTURE ADVECTION IS ANTICIPATED AS A DEEPENING LEE
SURFACE LOW AND STRONG LOW-LEVEL FLOW PERSIST. EXPECTATION IS FOR
DEWPOINTS TO GENERALLY BE IN THE LOW TO MID 60S EAST OF THE DRYLINE
ACROSS CENTRAL KS, WITH VALUES GRADUALLY INCREASING SOUTHWARD. WARM
TEMPERATURES ALOFT AND WEAK SYNOPTIC FORCING FOR ASCENT WILL LIKELY
KEEP THE WARM SECTOR FREE OF CONVECTION THROUGHOUT MOST OF THE DAY.
IMPETUS FOR CONVECTIVE INITIATION WILL LIKELY BE SURFACE CONVERGENCE
NEAR THE TRIPLE-POINT AND ALONG THE COLD FRONT AND DRYLINE. RECENT
GUIDANCE ALSO SHOWS A VERY SUBTLE SHORTWAVE MOVING INTO THE CENTRAL
PLAINS DURING THE AFTERNOON, WHICH WOULD ENHANCED LIFT ACROSS THE
REGION IF REALIZED. HIGH-RESOLUTION GUIDANCE, INCLUDING THE HREF, IS
IN GOOD AGREEMENT THAT CONVECTION INITIATION WILL OCCUR AROUND 21Z
ALONG THE DRYLINE IN CENTRAL KS.

WITH VERY STEEP MID-LEVEL LAPSE RATES AND STRONG INSTABILITY IN
PLACE, THE AIRMASS WILL BE PRIMED FOR EXPLOSIVE THUNDERSTORM
DEVELOPMENT ONCE CONVECTIVE INITIATION OCCURS. AN INITIALLY DISCRETE
STORM MODE IS ANTICIPATED ALONG THE DRYLINE IN KS WHILE A CLUSTERED
STORM MODE IS MORE LIKELY ALONG THE COLD FRONT FROM SOUTH-CENTRAL NE
ACROSS IA. VEERING WIND PROFILES ARE ANTICIPATED ALONG THE DRYLINE,
WITH CURRENT GUIDANCE SUGGESTING EFFECTIVE SRH OVER 250 M2/S2 AND
EFFECTIVE BULK SHEAR OVER 50 KT. THESE WIND PROFILES ARE MORE THAN
SUPPORTIVE OF SUPERCELLS, AND, GIVEN THE LIKELY DISCRETE INITIAL
MODE, TORNADOES. A FEW STRONG TORNADOES ARE POSSIBLE, PARTICULARLY
NEAR THE TRIPLE POINT WHERE THE PROBABILITY OF BACKED SURFACE WINDS
IS HIGHER. VERY LARGE HAIL (I.E. GREATER THAN 2 INCHES IN DIAMETER)
IS ALSO LIKELY WITH THE STORMS ALONG THE DRY LINE AS WELL AS INITIAL
DEVELOPMENT FARTHER NORTHEAST ALONG THE COLD FRONT. THE HAIL THREAT
WILL EXTEND INTO SOUTHERN WI AS THE LOW-LEVEL JET SUPPORTS
THUNDERSTORMS ALONG THE FRONTAL ZONE.

A MODERATE RISK FOR TORNADOES MAY BE WARRANTED IN SUBSEQUENT
OUTLOOKS
BUT THE CONFINED NATURE OF THE THREAT AND REMAINING
UNCERTAINTY REGARDING THE LOCATION OF THE TRIPLE-POINT DURING THE
AFTERNOON AS WELL AS THE EXTENT OF THE MOISTURE RETURN MERITS
WAITING FOR MORE CONFIDENCE BEFORE UPGRADING.

..CENTRAL HIGH PLAINS

UPSLOPE FLOW AND RESULTING CONVERGENCE WILL SUPPORT THE DEVELOPMENT
OF THUNDERSTORMS DURING THE AFTERNOON ACROSS NORTHEAST CO AND
ADJACENT PORTIONS OF SOUTHEAST WY AND SOUTHWEST NE PANHANDLE. SOME
ISOLATED HAIL IS POSSIBLE WITH THE STRONGEST STORMS.


This post has been edited by ClicheVortex2014: May 1 2018, 01:06 AM


--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post May 1 2018, 09:39 AM
Post #44




Rank: F5 Superstorm
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Posts: 22,556
Joined: 21-April 14
From: Dayton, Ohio
Member No.: 29,453





HRRR is pretty intense for later today. Multiple semi-discrete to discrete supercells.




--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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StL weatherjunki...
post May 1 2018, 10:28 AM
Post #45




Rank: F5 Superstorm
***

Group: Founding Member
Posts: 7,257
Joined: 10-June 07
From: Morgantown, WV
Member No.: 6,288





QUOTE(ClicheVortex2014 @ Apr 30 2018, 04:15 PM) *
As I stated in the first post, there's certainly some severe potential outside of the Plains which was missed by GFS (as I thought would happen)... but be very cautious about hour 84 NAM.

Good to see this broad western trough. It's been too long. Looks like there's gonna be multiple areas of significant hail producing supercells today as a part of a severe weather ramp up. Marginal yesterday, slight today, enhanced tomorrow (potential for small moderate IMO near the triple point in KS)... then probably a moderate on Wednesday.

I'm excited to watch the storms on GOES16 over the next few days. This should be the first time we get to watch storms blow up in a strongly unstable (2500-3000 CAPE) atmosphere.

I understand the NAM has a moist bias, which artificially inflates several important severe thunderstorm metrics. However, the NAM is advertising an area of elevated 0-1 km EHI values each afternoon well to the NE of the Plains hotspot. The temporal consistency of this feature peaks my attention and soundings in these areas are certainly favorable for severe thunderstorms. A forcing mechanism needed to initiate storms is not obvious, but the atmosphere is very moist and relatively uncapped so it won't take much.

Day 2: IN/OH
Attached Image


Day 3: Western NY
Attached Image


Day 4: VT/NH
Attached Image


I agree with regard to the GOES-16 imagery. Should be some amazing loops of the day: http://rammb.cira.colostate.edu/ramsdis/on...oop_of_the_day/


--------------------
All model guidance is just that, guidance. It is the responsibility of the forecaster to take that information, make it better, and appropriately communicate the improved forecast to users.

We live in a day and age where the quantity of model guidance is overwhelming, particularly within 24 hours of an event. We must remind ourselves that all models are wrong, but some are more useful than others.
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ClicheVortex2014
post May 1 2018, 11:55 AM
Post #46




Rank: F5 Superstorm
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From: Dayton, Ohio
Member No.: 29,453





Moderate risk for hail now. Uncertainty in potential for long-lived tornadoes due to a potentially rapid increase in CIN after sunset when the nocturnal LLJ kicks in.


QUOTE
Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
1144 AM CDT Tue May 01 2018

Valid 011630Z - 021200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS CENTRAL KS...

CORRECTED FOR CATEGORICAL GRAPHIC

...SUMMARY...
Numerous severe storms are expected over the central Great Plains to
the Mid-Missouri Valley. The most likely corridor is across parts of
central Kansas between 5 to 9 PM CDT. Tornadoes, a couple of which
could be strong, very large hail, and damaging winds will be
possible.

...Central Great Plains to the Upper MS Valley...
12Z soundings across central OK and north-central TX sampled mean
mixing ratios near 12 g/kg within a plume of 63-64 F surface dew
points. Richer moisture with upper 60s and lower 70s dew points
remains confined to south TX this morning. This suggests
boundary-layer moisture return is probably one day too early from
being optimal for a regional severe weather/tornado outbreak. Even
so, confidence is relatively large in storm initiation and probable
evolution in the late afternoon and evening, rendering increased
large hail probabilities.

The dryline is expected to mix across the eastern TX Panhandle and
western KS as surface temperatures warm into the 80s, creating a
T-intersection with a quasi-stationary front arcing across
west-central KS into eastern NE. A broad plume of MLCAPE from
2000-2500 J/kg is anticipated ahead in the warm/moist sector.
Guidance is consistent in ejecting a mid-level speed max ejects from
the southern High Plains into KS by 00Z. This should aid in ascent
for probable storm development in the 20-22Z time frame along the KS
portion of the dryline. Decreasing certainty exists farther south
along the dryline where weak mid-level height rises are anticipated
to occur this evening as the broader trough over southern CA digs a
bit farther south.

50-kt effective shear, nearly perpendicular deep-layer winds to the
dryline, and rather steep mid-level lapse rates will favor discrete
supercells producing very large hail. A few of these supercells may
become long-tracked across central KS and the threat for tornadoes
will increase between 22-02Z as storms encounter richer
boundary-layer moisture (toward the I-135 corridor) and as low-level
shear increases rapidly in response to a strengthening low-level
jet. The synoptic pattern is largely consistent with past Great
Plains cases of the evening low-level jet strengthening and aiding
in mid/late evening significant tornadoes. However, low-level
moisture may remain on the lower margins of what is typical of the
high-end events (with similar temperature profiles and hodograph
structures). The slightly drier boundary layer will encourage a
little quicker increase in convective inhibition, coincident with
the strengthening low-level shear. Thus, it is not clear whether or
not this scenario will evolve into a long-lived significant tornado
threat near sunset, or if the inhibition increase will tend to limit
the window of opportunity. Otherwise, clusters of storms (with
embedded supercells) should persist well into the overnight hours
with an attendant threat for large hail/damaging gusts and a couple
tornadoes, from the triple point northeastward along the
quasi-stationary front into the Upper MS Valley.

...Northeast CO...
An upslope flow regime will help maintain boundary-layer dewpoints
in the 40s across northeast CO through the afternoon, north of a
stalled front. Surface heating in cloud breaks will yield weak
surface-based buoyancy, while deep-layer vertical shear will be
favorable for supercells. A couple supercells may form this
afternoon in conjunction with the northern periphery of the
mid-level speed max ejecting into KS. These storms should move east
before weakening by mid-evening. Isolated large hail and strong
wind gusts will be possible.


HRRR still showing potential for multiple long-lived supercells. Note that updraft helicity only tells you about the strength of a rotating updraft, not about tornado potential. You can have strong updraft helicity (i.e., strong rotating updraft) without tornado potential... for example, elevated supercells.



This post has been edited by ClicheVortex2014: May 1 2018, 11:58 AM


--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post May 1 2018, 12:26 PM
Post #47




Rank: F5 Superstorm
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Group: Member
Posts: 22,556
Joined: 21-April 14
From: Dayton, Ohio
Member No.: 29,453





Good call by SPC with that moderate risk for hail. The atmosphere in the Plains is already categorically extremely unstable by LI. -9C showing up in northern Kansas and it's just past noon there. Already 3000 SBCAPE, 2500 MLCAPE.

Should be fun to watch the storms blow up today.


--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post May 1 2018, 12:28 PM
Post #48




Rank: F5 Superstorm
***

Group: Member
Posts: 22,556
Joined: 21-April 14
From: Dayton, Ohio
Member No.: 29,453





Latest HRRR showing problems with storm mode in north Kansas, however. But semi-discrete activity is shown further south.




This post has been edited by ClicheVortex2014: May 1 2018, 12:28 PM


--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post May 1 2018, 01:12 PM
Post #49




Rank: F5 Superstorm
***

Group: Member
Posts: 22,556
Joined: 21-April 14
From: Dayton, Ohio
Member No.: 29,453





Moderate risk for damaging winds for day 2


QUOTE
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1249 PM CDT Tue May 01 2018

Valid 021200Z - 031200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
NORTHEAST KANSAS INTO NORTHWEST MISSOURI...

...SUMMARY...
Severe thunderstorms are expected across parts of the southern and
central Plains into the middle Mississippi Valley Wednesday and
Wednesday night. Swaths of damaging winds, large to very large
hail, and a couple of tornadoes will be possible. Isolated to
scattered severe storms may also develop across parts of the
Midwest, with hail and damaging winds the primary threat.

...Synopsis...
A complicated forecast for Wednesday is apparent as a large-scale
mid- to upper-level trough over the western U.S. encroaches on the
Great Plains/Midwest. Uncertainty regarding some of the yet-to-be
resolved details remains, especially from southern KS into TX.
Deterministic models generally agree on the timing/evolution of a
mid-level vorticity maximum forecast to move from south-central NM
early Wednesday morning, to central KS into far northwestern
OK/northeast TX Panhandle by early evening, and subsequently moving
downstream across the lower MO Valley and reaching the southwestern
Great Lakes by daybreak Thursday. It is with the aforementioned
feature the greatest confidence in both severe thunderstorm
development/timing is associated.

...Central KS northeast into the middle MS Valley...
A corridor of warm advection related thunderstorm activity is
expected early in the morning near a warm front draped from
southeast NE east-northeast into the western Great Lakes. Low-level
moisture will increase during the day within strong southerly flow
from the central Plains east along the boundary. Steep mid-level
lapse rates in excess of 8 degrees C/km coupled with daytime heating
will contribute to strong instability developing by mid afternoon
over KS. Models suggest thunderstorms will develop as early as mid
afternoon near the dryline over central KS and develop northeast. A
tornado risk is possible with the more intense low-level
mesocyclones and a large to very large hail threat is possible. As
storms begin to congeal towards early evening over eastern KS and
southeast NE, the transition to severe-wind MCS is expected near the
aforementioned boundary. Localized significant severe gusts are
possible in association with any mesovortices and bowing segments.
The risk for damaging winds will lessen with eastward extent,
especially in areas near or east of the MS River late overnight.

...Southern KS into OK during the afternoon/evening...
A more conditional severe risk is expected farther south along the
dryline as weak large-scale forcing for ascent glances the area
during the late afternoon/early evening. Rich low-level moisture is
forecast to encompass much of the southern Plains with a capping
inversion expected to nullify thunderstorm development until
mid-late afternoon. Models show only isolated storm coverage and is
the primary impetus for severe uncertainty this forecast.
Nonetheless, MLCAPE is forecast to reach 3000 J/kg with upper 60s
boundary layer dewpoints with strong deep layer shear profiles. If
isolated/sustained updrafts manage to develop, discrete supercells
will be overwhelmingly favored. Mesoscale/storm-scale dependencies
will seemingly serve as the primary influencing factor(s) driving
the tornado risk---being highly conditional in some areas where
storm development is more in question. Low-level shear appears to
be modest (0-1 km SRH 50-150 m2/s2) with forecast hodographs
relatively limited in size until the early evening. However, the
supercell-supportive environment (strong deep-layer shear and large
buoyancy) will favor large to very large hail and isolated severe
gusts with the robust storms. Given the modest low-level shear
profiles, model depictions of augmented responses in hodograph
enlargement seemingly imply storm-scale or mesoscale influences may
largely drive the tornado risk.

...OK/TX during the evening/overnight...
A strong capping inversion will likely inhibit storm development
across TX during the day. However, during the evening/overnight,
isolated to scattered thunderstorms may develop near the dryline
from west TX northeast to the Red River. Models indicate isolated
to scattered storms will develop within a strengthening warm air
advection regime. Large hail/severe gusts will be the primary
hazards.


--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post May 1 2018, 01:14 PM
Post #50




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Cumulus developing along dryline now



--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post May 1 2018, 01:15 PM
Post #51




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From: Dayton, Ohio
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QUOTE
Mesoscale Discussion 0304
NWS Storm Prediction Center Norman OK
0110 PM CDT Tue May 01 2018

Areas affected...Central KS into southeast NE

Concerning...Severe potential...Tornado Watch likely

Valid 011810Z - 012045Z

Probability of Watch Issuance...95 percent

SUMMARY...One or two tornado watches will be needed by mid-afternoon
(20-21Z) across central Kansas into southeast Nebraska.

DISCUSSION...Surface mesoanalyses this afternoon showed an area of
low pressure located in northwest KS, while the equatorward-trailing
dryline was continuing to shift east through southwest KS. DDC
radar imagery showed this boundary located between KGCK and KDDC at
1740Z and into central portions of the OK and TX Panhandles.
Clearing skies per visible satellite imagery have allowed for
stronger surface heating across the warm sector where the
environment continues to moisten per southerly low-level winds.
These changes in boundary-layer thermodynamics (reduction in
inhibition) have allowed cumulus clouds to develop along the KS
portion of the dryline into adjacent part of the OK Panhandle, as
the environment further destabilizes (mixed-layer CAPE is already up
to 2500 J/kg).

Deeper moist convection is expected by 20-21Z along the KS dryline
as stronger ascent within the exit region of southwesterly mid- and
upper-level jets shift into the central Plains this afternoon and
evening. Trends in the operational HRRR continue to suggest storm
development along the KS portion of the dryline by 21Z, with some
potential for initiation by around 20Z. Further low-level moistening
and increasing vertically veering winds will support supercell
development with an attendant threat for all severe hazards.
Initial storms will be capable of producing very large hail, while a
tornado threat (some strong) will increase, given a strengthening
southerly low-level jet resulting in increased hodograph curvature
this evening.


--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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NorEaster07
post May 1 2018, 02:23 PM
Post #52




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From: SW Coastal CT
Member No.: 18,864






Chasers are ready... dews are up in the 60s up to Iowa now... Mid 60s for Oklahoma.

Storm Chaser mapped out with their current position right now. Looks like most of them are in Kansas. The outlines is for Severe weather.

Attached Image


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ClicheVortex2014
post May 1 2018, 03:01 PM
Post #53




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This situation is much more worthy of a PDS watch than 4/13 was. But anyway... borderline PDS



--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post May 1 2018, 03:04 PM
Post #54




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From: Dayton, Ohio
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First warning is up. Didn't take long.

Edit: it's warned for 2" hail blink.gif



This post has been edited by ClicheVortex2014: May 1 2018, 03:07 PM
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--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post May 1 2018, 03:27 PM
Post #55




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From: Dayton, Ohio
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Some warm sector cells are popping north of Salina, KS. The dryline cells that are popping are getting too close to eachother for comfort. Watch for a cell to take a right turn, a warm sector cell to establish itself, or watch the activity further south because that's looking more discrete.

This post has been edited by ClicheVortex2014: May 1 2018, 03:31 PM


--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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PlanetMaster
post May 1 2018, 04:03 PM
Post #56




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Posts: 1,585
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From: Babylon, NY
Member No.: 25,093





Very unstable right up against the dry line, 3000 J/kg CAPE signature widespread.

Sat with CAPE overlay


Radar with CAPE overlay, storms right in the zone.


--------------------
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ClicheVortex2014
post May 1 2018, 04:04 PM
Post #57




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From: Dayton, Ohio
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The supercell just south of the NE/KS border has some potential I think. Nothing to its north, only something to the south but might not be interfering with the inflow.
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--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post May 1 2018, 04:07 PM
Post #58




Rank: F5 Superstorm
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From: Dayton, Ohio
Member No.: 29,453





Still got an hour or two until the nocturnal LLJ starts kicking in.
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--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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so_whats_happeni...
post May 1 2018, 04:10 PM
Post #59




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From: Millersville, PA
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QUOTE(ClicheVortex2014 @ May 1 2018, 04:27 PM) *
Some warm sector cells are popping north of Salina, KS. The dryline cells that are popping are getting too close to eachother for comfort. Watch for a cell to take a right turn, a warm sector cell to establish itself, or watch the activity further south because that's looking more discrete.


To this day storm mode is still one of the hardest processes for me to grasp as to just looking at parameters (SPC page). As we are seeing today a line forming along the dry line while say a hundred miles east are seeing discrete/cluster cell formation. Amazing almost seems like when the energy or dry punch pushes over the region it almost just pops the storm activity all along the region from KS up into IA and up further north we have largely discrete cells as well.

Would love to further get involved in the severe weather aspect of things and how things just go boom out there been trying to pick apart goes 16 imagery to get an idea. In other parts of the country we tend to have much more discernable factors to which we can tell how things will progress but the area across the midwest/plains is just, to me, an unknown idea.


--------------------
Tylor Cartter

B.S. in Meteorology
Millersville University


Weather Observer:
KMDT: Harrisburg International Airport
KBWI: Baltimore/ Washington International Airport

Stratosphere Discussion:
2016/2017
2017/2018


AccuWeather Forum MidAtl/NE Snowfall Forecasting Champion Winter 2017
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ClicheVortex2014
post May 1 2018, 04:13 PM
Post #60




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The southern, more discrete cells are tornadic now too. The one further north does appear to be getting interfered with.
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--------------------
Meteorology undergrad at Ohio University (weather on campus)

Historic weather events in the Ohio Valley:
- The 1974 Super Outbreak (read more)
- The 2012 "Super" Derecho
- The Great Blizzard of 1978

2018 Weather for Cincinnati

Days >90: 6 (Last: 6/17/18)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 14 (Last: 6/12/18)
Slight risks: 5 (Last: 5/31/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 1 (Last: 4/3/18)
High risks: 0 (Last: 11/17/13)
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