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> March 17-18 Plains/MW/OV/GL Severe Weather, Long-range (6-10 days): forecasts and observations
ClicheVortex2014
post Mar 11 2018, 03:14 PM
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GEFS analogs as well as Euro and GFS OP are picking up on severe weather in the Plains, possibly spreading into the OV/lower Great Lakes the day after (but we all know how that goes)

Both models have an intense negatively tilted trough coming into the Plains. Appears to be enough moisture ahead of it and, without a doubt, the focus is on eastern OK/eastern KS/Arkansas.

% of analogs based on 105 GEFS analogs


GFS



Euro



This post has been edited by ClicheVortex2014: Mar 17 2018, 06:34 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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post Mar 11 2018, 03:19 PM
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Beautiful setup with a dryline and stationary front next weekend





--------------------
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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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snowlover2
post Mar 11 2018, 03:23 PM
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SPC does mention this a little bit in the 4-8 day outlook.

QUOTE
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0146 AM CST Sun Mar 11 2018

Valid 141200Z - 191200Z

...DISCUSSION...
Large-scale pattern is expected to remain unfavorable for organized
severe thunderstorms much of the upcoming medium-range period.
However, 00z guidance suggests upper ridging will shift from the
Plains into the OH Valley/Gulf States region by day8 which will
allow more favorable low-level trajectories to develop across the
Gulf basin for moisture to advance inland by the end of the week.
While there are notable differences among the models, there is
increasing confidence that upper heights will begin to fall across
the Rockies into the Plains next weekend and this could aid
convective development along western plume of aforementioned
moisture return. At this time there is too much uncertainty to
introduce severe probs but the large-scale pattern may evolve such
that strong convection ultimately materializes toward the end of the
medium-range period.

..Darrow.. 03/11/2018


--------------------
# of T-Storm Watches:3

# of T-Storm Warnings:4

# of Tornado Watches:3

# of Tornado Warnings:1
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ClicheVortex2014
post Mar 11 2018, 03:26 PM
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QUOTE(snowlover2 @ Mar 11 2018, 03:23 PM) *
SPC does mention this a little bit in the 4-8 day outlook.

I've fallen out of the habit of reading their 4-8 day outlooks... it's just been so much of the same over the past 5 months. I think we're about done with that now though.

This post has been edited by ClicheVortex2014: Mar 11 2018, 03:27 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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post Mar 11 2018, 05:23 PM
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A key to this potential event is actually the 2 weak systems that come 48-60 hours before it;

They advect steeper lapse rates into the Plains and Midwest
They enhance moisture return

The 2nd system is stronger than the first, and it moves northeast through the Great Lakes. The cold front trailing behind it is weakening, and in the southern Plains, is stalling. Exactly when/how far south this front stalls is key to how far north the event is on Sunday... and potentially the magnitude of the event.



Check out the lapse rates in Mexico and the Rockies


24 hours later



This post has been edited by ClicheVortex2014: Mar 11 2018, 05:29 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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post Mar 11 2018, 11:31 PM
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GFS has trended toward a weaker system over the past 3 runs... and just like the last system, low-level winds are too weak for a big tornado threat. I think the timing with the trough ejecting is also unfavorable.

Still a week out, wouldn't write this off yet.




This post has been edited by ClicheVortex2014: Mar 11 2018, 11:32 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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post Mar 12 2018, 10:02 AM
Post #7




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Still getting mention among the pro Meteorologists.

QUOTE
FRIDAY 3/16
A chance of an isolated severe thunderstorm in the east half of OK, east TX, west AR, northwest LA. TORCON - 2 or less

A trough of low pressure develops to the lee of the Rockies with a trough along a weak warm front eastward into north TX and OK, pulling low-level moisture northward. But conditions aloft are dry, low-level winds weak, and upper forcing weak, so the severe threat should be low. Computer models disagree on details of the forecast.

SATURDAY 3/17
There could be some severe thunderstorms in the Southern Plains and lower Mississippi Valley, but computer models differ on the solution enough that I'll defer on making a forecast until tomorrow.


QUOTE
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0239 AM CDT Mon Mar 12 2018

Valid 151200Z - 201200Z

...DISCUSSION...
Late-evening model guidance is gradually evolving toward a
potentially more active convective pattern by the end of the
medium-range period. Eastern US trough that will suppress Gulf air
mass should shift east within a few days allowing
higher-moisture-content air mass to begin advancing north into TX
day4-5. Much of the lower latitudes are expected to moisten
significantly into early next week.

Threat of deep convection will begin increasing from the Arklatex
into the TN Valley during the day5-6 time frame. However, timing of
individual short waves will prove extremely difficult as
ECMWF/GFS/UKMET/Canadian exhibit different solutions to the break
down of the Plains ridge late in the week. While model differences
will certainly extend into early next week, Plains ridge should
progress into the MS Valley by day8. If this occurs there is some
concern organized severe may ultimately materialize across the
southern Plains/lower MS Valley. Will not introduce 15% severe probs
given the uncertainty but this scenario will be monitored closely.


--------------------
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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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ColoradoChinook
post Mar 12 2018, 12:17 PM
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Hey Clichevortex - look up "tornado forecasting workshop with Rich Thompson" on Youtube. There are 9 very informative lectures by Rich Thompson at an OU lecture hall.
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ClicheVortex2014
post Mar 12 2018, 08:24 PM
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QUOTE(ColoradoChinook @ Mar 12 2018, 12:17 PM) *
Hey Clichevortex - look up "tornado forecasting workshop with Rich Thompson" on Youtube. There are 9 very informative lectures by Rich Thompson at an OU lecture hall.

Already watched all of them back before I started Meteorology classes. Only thing I didn't understand at the time was QG theory... which I've learned about this semester and have a decent grasp on it.

I understand that apparently they've done another workshop recently? I watched the ones back in 2014... can't imagine they'd be much different. But it was definitely worth the watch.

This post has been edited by ClicheVortex2014: Mar 12 2018, 08:39 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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post Mar 12 2018, 10:53 PM
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The last 4 GFS runs have trended toward a significantly stronger system on Friday.








--------------------
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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post Mar 12 2018, 11:27 PM
Post #11




Rank: F5 Superstorm
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From: Dayton, Ohio
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The result is a weak severe threat (weak directional and vertical shear) followed by a couple systems that are so weak and in rapid succession that they can't draw enough moisture north. The exception is the final piece of energy in this trough, which, although GFS hasn't loaded that far out yet, I suspect is going to cause some crazy parameters.


--------------------
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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post Mar 13 2018, 11:14 PM
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It appears instead of the initial solution... a bunch of non-events followed by a potentially significant event... it's going to be a bunch of marginal/slight risks. The western trough is going to stick around longer than initially thought.

GFS has an interesting event on Monday in Dixie Alley as the western trough finally moves east... but I wouldn't count on that after all this variability.

There's a new trough in the west as of 00z Tuesday. Fun pattern.


--------------------
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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post Mar 14 2018, 12:16 PM
Post #13




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





I like how he provides a mini-discussion 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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post Mar 14 2018, 10:45 PM
Post #14




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From: Dayton, Ohio
Member No.: 29,453





The trend over the past 4 GFS runs has been to bring the system further south, including the trough. In theory, this would enhance the severe threat because part of the issue was that the parent low/trough were too far separated from the warm sector causing weaker forcing and weaker shear.

Last nights run


Tonights run


--------------------
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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post Mar 14 2018, 10:50 PM
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From: Dayton, Ohio
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Seeing this reflected in the EHI values, and especially the soundings.

EHI on last nights run


EHI tonight


Sounding in the EHI maximum last night (I picked far east Texas; as far as I'm aware, nothing is gonna happen in south Texas)


Sounding in the EHI maximum tonight


Huge difference in the winds. Quite a bit more favorable for supercells.

This post has been edited by ClicheVortex2014: Mar 14 2018, 10:54 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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post Mar 15 2018, 12:46 AM
Post #16




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From: Dayton, Ohio
Member No.: 29,453







QUOTE
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1139 PM CDT WED MAR 14 2018

VALID 161200Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE LOWER MS VALLEY...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE LA
COAST TO EASTERN KS...

..SUMMARY

SCATTERED SEVERE THUNDERSTORMS ARE POSSIBLE ACROSS THE LOWER/MID
MISSISSIPPI VALLEY INCLUDING THE THREAT OF LARGE HAIL, DAMAGING
WINDS, AND PERHAPS A FEW TORNADOES.

..LOWER/MID MISSISSIPPI VALLEY

A FOCUSED AREA OF STRONG MID-LEVEL HEIGHT FALLS WILL SPREAD ACROSS
THE CENTRAL PLAINS DURING THE DAY2 PERIOD AHEAD OF A PRONOUNCED
SHORT-WAVE TROUGH THAT SHOULD EXTEND FROM NE-OK AT 18Z...AND
IA-NORTHERN AR AT 17/06Z. LATEST NAM GUIDANCE IS A BIT SLOWER THAN
EARLIER RUNS AND MORE CLOSELY RESEMBLES THE ECMWF WHICH HAS BEEN
FAIRLY CONSISTENT WITH THE EJECTION OF THIS FEATURE. GIVEN THIS
SCENARIO, PRIMARY CORRIDOR OF LARGE-SCALE FORCING FOR ASCENT SHOULD
FOCUS AHEAD OF THE SURFACE LOW FROM NE/KS INTO MO AND ONLY GLANCE
LATITUDES AS FAR SOUTH AS I-40. EVEN SO, PRIMARY PLUME OF MOISTENING
IS EXPECTED TO SPREAD ACROSS THE LOWER MS VALLEY WITH UPWARDS OF 1"
PW LIKELY SUFFICIENT FOR SURFACE-BASED CONVECTION AT PEAK HEATING
ACROSS PORTIONS OF AR/LA. NAM STRONGLY HEATS/MIXES THE BOUNDARY
LAYER EAST ACROSS OK DURING THE DAY AND A WELL-DEFINED WIND SHIFT
WILL EXTEND FROM SOUTHWEST MO INTO NORTHEAST TX AT 17/00Z. IT
APPEARS SURFACE HEATING WILL PROVE INSTRUMENTAL IN THUNDERSTORM
DEVELOPMENT ALONG THIS BOUNDARY WHERE VERY STRONG SHEAR WILL SUPPORT
ROTATING UPDRAFTS. DATA CONTINUES TO SUGGEST AT LEAST ISOLATED
SUPERCELL DEVELOPMENT ACROSS SOUTHERN AR/NORTHERN LA BY EARLY
EVENING THAT SHOULD SPREAD TOWARD NORTHWEST MS AFTER DARK. HAIL,
DAMAGING WINDS, AND A FEW TORNADOES WILL BE POSSIBLE WITH THE
SURFACE-BASED ACTIVITY AND PRIMARILY HAIL NORTH OF THE WARM FRONT
OVER NORTHEAST AR/WESTERN TN.

FARTHER NORTH ACROSS EASTERN KS/WESTERN MO, WHILE PW WILL BE QUITE
SCANT WITH VALUES STRUGGLING TO REACH .75", STRONG BOUNDARY-LAYER
HEATING IS EXPECTED TO STEEPEN SURFACE-3KM LAPSE RATES TO NEAR 9
C/KM AHEAD OF THE SURFACE LOW. THIS SHOULD ENCOURAGE SURFACE-BASED
CONVECTION THAT MAY GENERATE A FEW ROBUST UPDRAFTS ALONG A NARROW
CORRIDOR FROM EASTERN KS INTO WEST-CENTRAL MO. LOW SEVERE PROBS HAVE
BEEN EXTENDED INTO THIS REGION TO ACCOUNT FOR STRONG WIND GUSTS OR
MARGINALLY SEVERE HAIL.


--------------------
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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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StL weatherjunki...
post Mar 15 2018, 09:32 AM
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Not necessarily related to this system, but it seems like the dryline location associated with this system could be representative of the dryline location for the next couple weeks according to total QPF from the 00z GEFS. Given the location, more-or-less smack dab in the middle of tornado alley, it seems like severe thunderstorm season will be ramping up in line with climatology unlike last season. Have to wonder what the season looks like come May ph34r.gif
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--------------------
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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StL weatherjunki...
post Mar 15 2018, 09:52 AM
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From: Morgantown, WV
Member No.: 6,288





QUOTE(StL weatherjunkie @ Mar 15 2018, 10:32 AM) *
Not necessarily related to this system, but it seems like the dryline location associated with this system could be representative of the dryline location for the next couple weeks according to total QPF from the 00z GEFS. Given the location, more-or-less smack dab in the middle of tornado alley, it seems like severe thunderstorm season will be ramping up in line with climatology unlike last season. Have to wonder what the season looks like come May ph34r.gif

Also, looking at the drought monitor the average dryline location is likely highly dependent on soil moisture. If I were a betting man, I'd be willing to bet money that the dry line sets up east of the extreme drought region throughout most of the spring.

This post has been edited by StL weatherjunkie: Mar 15 2018, 09:52 AM
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--------------------
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 Mar 15 2018, 02:01 PM
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From: Dayton, Ohio
Member No.: 29,453





QUOTE(StL weatherjunkie @ Mar 15 2018, 09:52 AM) *
Also, looking at the drought monitor the average dryline location is likely highly dependent on soil moisture. If I were a betting man, I'd be willing to bet money that the dry line sets up east of the extreme drought region throughout most of the spring.

Agreed. SWH and I had a discussion in the spring thread about the implications of the drought with respect to EMLs. Eric Webb on Twitter said the drought may enhance the frequency and strength of the EMLs, which would make this severe season even more interesting.

We now have 3 severe weather days to watch... Friday, Sunday, and Monday. Nice.


QUOTE
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1227 PM CDT Thu Mar 15 2018

Valid 161200Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTHERN LOUISIANA...ARKANSAS...MISSISSIPPI AND WESTERN TENNESSEE...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
LOWER TO MID MISSISSIPPI VALLEY...ARKLATEX...TENNESSEE VALLEY...AND
LOWER MISSOURI VALLEY...

...SUMMARY...
Scattered severe thunderstorms are possible across parts of the
lower to mid Mississippi Valley including the threat of large hail,
damaging winds, and perhaps a few tornadoes.

...Lower to Mid Mississippi Valley/Lower Missouri Valley...
An upper-level low will move across the central Plains on Friday as
an associated negatively-tilted shortwave trough moves across the
southern Plains. Ahead of the system, low-level moisture advection
will take place across the Arklatex and lower Mississippi Valley.
Surface dewpoints will gradually increase into the lower to mid 60s
F across northern Louisiana into parts of eastern Arkansas and
western Mississippi. Thunderstorm development will likely take place
during the day across eastern Louisiana and western Mississippi near
the axis of a 30 to 40 kt low-level jet. Thunderstorms will also be
possible during the afternoon further to the west along a corridor
of instability. Convection may also develop during the day just
ahead of the shortwave trough from Nebraska southeastward into
Missouri associated with the leading edge of large-scale ascent.
This convection should persist into the evening as the upper-level
low moves into the mid Missouri Valley.

A 55 to 70 kt mid-level jet will move through the base of the
upper-level system creating strong deep-layer shear across the
slight risk area. NAM forecast soundings from Monroe, Louisiana
northeastward to near Memphis show 0-6 km shear generally from 50 to
60 kt with substantial directional shear in the lowest 1 km above
ground level. This wind profile should support supercell development
with cells that can initiate along the instability axis. Although
isolated large hail and wind damage will likely accompany
supercells, storm coverage near the strongest instability may remain
more isolated. Any supercells that can develop and persist into the
late afternoon may also have a tornado threat due to favorable
low-level shear. Convection that develops further to the east into
eastern Louisiana and western Mississippi will be located in weaker
instability keeping the preferred storm mode as multicellular. Wind
damage will still be possible with these storms. Instability is also
forecast to be weaker from north-central Arkansas into central
Missouri and northeast Kansas. A few marginally severe thunderstorms
with strong wind gusts and hail will be possible along this corridor
during the early afternoon.



QUOTE
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0252 AM CDT Thu Mar 15 2018

Valid 181200Z - 231200Z

...DISCUSSION...
Very active flow regime will be noted through the medium range as
numerous short waves progress quickly across the US. Of particular
note will be a trough that migrates across southern CA during the
day3 period into the southern Rockies mid day Sunday. While there is
some discrepancy among the models, it appears a very strongly forced
exit region will overspread KS/OK with a 110kt 500mb speed max
depicted by latest ECMWF along the Red River at 19/06z. There is
some concern that moisture north of the Red River may be
marginalized due to possible day3 convective influences; however,
steep lapse rates and strong forcing suggest ample buoyancy should
be present for possible organized severe.

Downstream, a pseudo-stationary warm front will be draped from
northern MS along the AR/LA border into northeast TX during the day4
period. Strengthening westerly flow above the boundary layer
suggests an east-west corridor of organized convection may evolve
along this boundary during the period, especially late. If this
materializes then convective processes may disrupt organized severe
threat downstream day5. For these reasons have not introduced severe
beyond the day4 period.






--------------------
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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
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ClicheVortex2014
post Mar 15 2018, 02:46 PM
Post #20




Rank: F5 Superstorm
***

Group: Member
Posts: 22,676
Joined: 21-April 14
From: Dayton, Ohio
Member No.: 29,453





Might have to open a thread for SE US severe weather... wow





--------------------
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: 18 (Last: 7/14/18) (Highest: 96)
Days <0: 5 (Last 1/6/18) (Lowest: -7)
Marginal risks: 19 (Last: 7/10/18)
Slight risks: 6 (Last: 6/26/18)
Enhanced risks: 0 (Last: 11/5/17)
Moderate risks: 2 (Last: 7/20/18)
High risks: 0 (Last: 11/17/13)
Go to the top of the page
 
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