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> July 18-20 Plains/MW/GL/OV Severe Weather, SPC Risk Level; Day 1 Moderate Risk: Forecasts and OBS
WeatherMonger
post Jul 18 2018, 08:04 PM
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Might as well get an OBS/FC thread going. Not offline yet.


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snowlover2
post Jul 18 2018, 08:15 PM
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Wouldn't be surprised if the current day 3 slight risk gets shifted north and east into Ohio on the new day 2 in a few hours seeing that both NAM and 3K NAM show the storms in IN/OH.


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

# of T-Storm Warnings:4

# of Tornado Watches:3

# of Tornado Warnings:1
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snowlover2
post Jul 19 2018, 12:40 AM
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QUOTE(snowlover2 @ Jul 18 2018, 09:15 PM) *
Wouldn't be surprised if the current day 3 slight risk gets shifted north and east into Ohio on the new day 2 in a few hours seeing that both NAM and 3K NAM show the storms in IN/OH.

Not only was I right about the slight risk but a small enhanced added as well for IN/KY.
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QUOTE
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1227 AM CDT THU JUL 19 2018

VALID 201200Z - 211200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE OHIO AND TENNESSEE VALLEYS...

..SUMMARY

SCATTERED SEVERE THUNDERSTORMS ASSOCIATED WITH LARGE HAIL, WIND
DAMAGE AND A TORNADO THREAT WILL BE POSSIBLE FRIDAY AFTERNOON AND
EVENING ACROSS PARTS OF THE OHIO AND TENNESSEE VALLEYS.

..OHIO AND TENNESSEE VALLEYS

AN UPPER-LEVEL TROUGH WILL MOVE INTO THE OHIO AND TENNESSEE VALLEYS
ON FRIDAY AS AN UNSEASONABLY STRONG MID-LEVEL JET MOVES THROUGH THE
SOUTHWESTERN SIDE OF THE SYSTEM. AT THE SURFACE, A LOW IS FORECAST
TO MOVE EAST-SOUTHEASTWARD ACROSS NORTHERN ILLINOIS DURING THE DAY
AS A COLD FRONT ADVANCES EASTWARD ACROSS THE MID MISSISSIPPI VALLEY.
AHEAD OF THE FRONT, A VERY MOIST AIRMASS SHOULD BE IN PLACE WITH
SURFACE DEWPOINTS IN THE LOWER 70S F. THIS SHOULD ENABLE A CORRIDOR
OF MODERATE TO STRONG INSTABILITY TO DEVELOP AHEAD OF THE FRONT BY
AFTERNOON. AS LOW-LEVEL CONVERGENCE INCREASES ALONG THE FRONT,
THUNDERSTORMS ARE FORECAST TO FORM DURING THE EARLY TO MID AFTERNOON
IN THE MID MISSISSIPPI VALLEY WITH THE STORMS MOVING SOUTHEASTWARD
ACROSS THE OHIO AND TENNESSEE VALLEYS DURING THE LATE AFTERNOON AND
EARLY EVENING.

FORECAST SOUNDINGS FOR PADUCAH, KY, EVANSVILLE, IN AND LOUISVILLE,
KY AT 00Z ON SATURDAY SHOW MLCAPE VALUES OF 2500 TO 3000 J/KG, 0-6
KM SHEAR OF 40 TO 50 KT AND STEEP MID-LEVEL LAPSE RATES. THIS
ENVIRONMENT SHOULD BE FAVORABLE FOR SUPERCELLS WITH LARGE HAIL.
HAILSTONES OF GREATER THAN 2 INCHES WILL BE POSSIBLE WITH THE MOST
INTENSE CELLS. AS THE LOW-LEVEL JET STRENGTHENS DURING THE EARLY
EVENING, 0-3 KM STORM-RELATIVE HELICITY IS FORECAST TO REACH THE 200
TO 250 M2/S2 RANGE. THIS SHOULD BE ENOUGH FOR A TORNADO THREAT WITH
THE MORE DOMINANT SUPERCELLS. STORM COVERAGE IS EXPECTED TO INCREASE
MARKEDLY BY EARLY EVENING AS AN MCS ORGANIZES ACROSS THE OHIO AND
TENNESSEE VALLEYS. IN RESPONSE, THE WIND-DAMAGE THREAT SHOULD
GRADUALLY INCREASE DURING THE LATE AFTERNOON AND EARLY EVENING AS
SUPERCELLS OR BOWING LINE SEGMENTS MOVE SOUTHEASTWARD ACROSS THE
INSTABILITY CORRIDOR.

AT THIS TIME, THE MODELS ARE IN GOOD AGREEMENT CONCERNING FRIDAY'S
SCENARIO. THE ENVIRONMENT WILL LIKELY SUPPORT A SUBSTANTIAL SEVERE
THREAT ACROSS THE OHIO AND TENNESSEE VALLEYS SO THIS OUTLOOK
INCLUDES AN UPGRADE TO ENHANCED RISK.

..MAXIMUM RISK BY HAZARD

TORNADO: 5% - SLIGHT
WIND: 30% - ENHANCED
HAIL: 30% - ENHANCED

..BROYLES.. 07/19/2018


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

# of T-Storm Warnings:4

# of Tornado Watches:3

# of Tornado Warnings:1
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FireworkWX03
post Jul 19 2018, 01:44 AM
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Very interested to see how this one pans out. The NAM is showing the kind of healthy summertime MCS that has been wholly absent from the region (and most of the country, really) so far this year.

Not liking the rain totals for northern Ohio though. We're dry as a bone and the westward shift of precip out of the area will only stress things further. Although northern Indiana needs it too so not an awful setup. If the GFS is to be believed there will be more opportunities for boomers through mid next week at least.
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WeatherMonger
post Jul 19 2018, 08:08 AM
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Now in the slight risk.

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QUOTE
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 AM CDT Thu Jul 19 2018

Valid 191300Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
INTO EARLY TONIGHT OVER PARTS OF IOWA...MISSOURI...EASTERN KANSAS
AND ILLINOIS....

...SUMMARY...
The greatest threat for organized severe thunderstorms will be this
afternoon into early tonight over parts of Iowa, Missouri, eastern
Kansas, and Illinois.

...Synopsis...
In mid/upper levels, a persistent and strong high will shift slowly
eastward over the southeastern Great Basin and Four Corners regions
through the period, its eastward-extending ridging contributing to
an expanding area of hot surface conditions over the southern
Plains. As this occurs, a strong, negatively tilted shortwave
trough -- with embedded/compact cyclone evident over the eastern
Dakotas -- will amplify somewhat and shift east-southeastward across
the upper Mississippi Valley. By 00Z the 500-mb low should reside
over southern MN, with troughing southeastward across eastern
IA/northern IL and northward over northern MN. By 12Z, that trough
should extend from northeastern MN to northern KY, with embedded low
over south-central/southwestern WI.

At the surface, 11Z analysis showed a frontal-wave low between
ATY-RWF, with cold front southwestward across northwestern KS, and
warm front southeastward over central portions of IA/MO into the
Mid-South. The warm front is expected to move east-northeastward
across eastern IA/MO and portions of IL through 06Z as the low
shifts east-southeastward across southern MN, and the cold front
crosses IA, northwestern MO, and portions of northern/central KS.
The western frontal segment over the High Plains of KS/CO will
weaken and stall late in the period.

...IA/MO/IL and vicinity...
Scattered thunderstorms are expected to develop along both fronts
from midday through evening across the slight-risk area, as well as
on residual warm-sector boundaries over MO. All severe modes will
be possible, including the potential for very large/damaging hail
from supercells over parts of IA/MO.

Given the strong directional shear, favorable deep shear (e.g.,
effective-shear magnitudes 45-60 kt), and strong buoyancy,
supercells will be possible. Within a warm sector that narrows with
northward extent, moisture from eastern KS northeastward and
eastward will be very rich, with surface dew points commonly upper
60s to mid 70s F, PW 1.5-2 inches, and mean mixing rations commonly
16-17 G/kg (locally approaching 19 g/kg). When diabatic surface
heating is factored in, this yields MLCAPE 3500-5000 J/kg in
modified RAOBs and forecast soundings.

Relatively sustained/discrete supercells with substantial residence
time in the warm sector will have the greatest potential for very
large/damaging hail, given the high inflow-layer water content,
sufficiently steep low/middle-level lapse rates, and storm-scale
hail-nucleus residence time inferred by both the ambient-flow
geometry and very deep buoyant layers. Forecast soundings and hail
model suggest highest LIs and 1/3-1/4 of CAPE will reside in
favorable hail-growth areas aloft. Some tornado potential also
exists, but very conditional and dependent on localized
boundary/storm-scale/vorticity-processing considerations, given
rather modest ambient near-surface flow.

Clustered or QLCS modes may develop and move southeastward along and
southwest of the warm front this evening, offering a lowering threat
for hail but better-organized wind potential. At this time,
specific foci/location/timing for upscale growth appears too
uncertain to highlight a smaller corridor of greater wind
probabilities, but one may be justifiable in subsequent updates as
influential mesoscale factors become more apparent
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Dan Mirgon
post Jul 19 2018, 12:34 PM
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How's it looking for Lake Cumberland. I'm on a houseboat till Sunday....


--------------------
Holding Down SE Ohio.
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snowlover2
post Jul 19 2018, 12:44 PM
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New day 2 has an expansion of the enhanced area although somewhat surprised it's not more north. 12z NAM shows a line of intense looking storms tomorrow night moving through most of IN/OH. Might see it shift north tonight on new day 1 if that continues.

Attached Image

QUOTE
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1236 PM CDT Thu Jul 19 2018

Valid 201200Z - 211200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR SOUTHERN
IL/IN...CENTRAL/WESTERN KY...MIDDLE/WESTERN TN...NORTHERN MS/AL...

...SUMMARY...
Scattered severe thunderstorms associated with large hail, wind
damage and a tornado threat will be possible Friday afternoon and
evening across parts of the MIssissippi, Ohio and Tennessee Valleys.

...Synopsis...
An anomalously strong deep layer trough and associated surface
cyclone are expected to move southeastward from the upper Midwest
into portions of the lower Great Lakes on Friday. The surface
pattern will be complicated by one or more convectively-induced
outflow boundaries, with a synoptic-scale surface trough/cold front
expected to progress eastward south of the surface low through the
period. A stout EML will spread eastward from the southern Plains
over rich low-level moisture, resulting in a volatile thermodynamic
environment developing over portions of the MS/TN/OH River Valleys
and the Midwest.

...MS/TN/OH River Valleys into the Midwest...
A potentially significant severe thunderstorm episode is possible
across portions of the MS/TN/OH Valleys and the Midwest on Friday,
though considerable uncertainty remains regarding convective
evolution through the period.

One or more clusters of convection will likely be ongoing Friday
morning, though the remnants of these clusters are expected to push
east through the day, allowing for moderate-to-strong
destabilization in their wake. The strongest focus for convection
will be the surface trough moving through IL/IN/OH, though this area
will be somewhat removed from the stronger shear and instability,
especially with northward extent.

Foci for convective initiation will be more subtle further south and
west, but the environment will also be much more volatile, with
strong instability (MLCAPE of 2500-4000 J/kg possible) and effective
shear (45-60 kt) in place. Scattered thunderstorms are expected to
develop during the afternoon, potentially along the trailing surface
boundary and also evolving out any early day elevated convection.
Initially discrete storm modes will favor large hail (potentially
greater than 2 inches in diameter), along with damaging wind gusts
and a tornado or two. With time, evolution into one or more
upscale-growing clusters is expected into the evening. Any such
clusters would be capable of producing damaging wind swaths as they
propagate to the southeast.

...Southern/Central Plains...
Confidence in convective initiation is much lower across portions of
northwest AR westward into northern OK and southern KS. However,
very strong heating in the presence of a weak surface boundary may
support isolated development during the afternoon. Additionally,
there is some potential for elevated convection to develop across
this region, either early or late in the period. Given the very
favorable instability/shear environment across this region, a
conditional risk of severe hail and wind will be present across this
area.

...MAXIMUM RISK BY HAZARD...
Tornado: 5% - Slight
Wind: 30% - Enhanced
Hail: 30% SIG - Enhanced

..Dean/Dial.. 07/19/2018


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

# of T-Storm Warnings:4

# of Tornado Watches:3

# of Tornado Warnings:1
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WeatherMonger
post Jul 19 2018, 02:02 PM
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Gonna be much ado about nothing around here. Been cloudy all day and had a brief shower late morning. Was surprised to not be moved out of the slight risk or even marginal at the 1630z update. Suspecting they will trim the eastern edge on the next update.
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melissa from ill...
post Jul 19 2018, 03:20 PM
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QUOTE(WeatherMonger @ Jul 19 2018, 02:02 PM) *
Gonna be much ado about nothing around here. Been cloudy all day and had a brief shower late morning. Was surprised to not be moved out of the slight risk or even marginal at the 1630z update. Suspecting they will trim the eastern edge on the next update.


They didnt drop us out of the slight. The suns been shining strong here right after that rain shower passed.


--------------------
"Auntie Em, Uncle Henry, its a TWISTER its a TWISTER!"
"I gotta go, we got COWS!"
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snowlover2
post Jul 19 2018, 03:28 PM
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There's a tornado watch in SE IA and a few tornado warnings as well.


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

# of T-Storm Warnings:4

# of Tornado Watches:3

# of Tornado Warnings:1
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snowlover2
post Jul 19 2018, 04:27 PM
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The cell between Des Moines IA and Ottumwa looks very impressive and has had a confirmed tornado for a lengthy time.


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

# of T-Storm Warnings:4

# of Tornado Watches:3

# of Tornado Warnings:1
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CentralIllinois
post Jul 19 2018, 04:28 PM
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QUOTE(snowlover2 @ Jul 19 2018, 03:28 PM) *
There's a tornado watch in SE IA and a few tornado warnings as well.

.
Attached image(s)
Attached Image
 


--------------------

Severe Thunderstorm Watch:3
Severe Thunderstorm Warning:7
Tornado Watch:2
Tornado Warning:1


2017-2018 Snowfall:15.6"
2016-2017 Snowfall:6.3"
2015-2016 Snowfall:14.7"
2014-2015 Snowfall:27.8"
2013-2014 Snowfall:42.8"
2012-2013 Snowfall:24.4"


Note to Accuweather.com....Please give us a dedicated video blogger for the Plains/MW/OV/GL area!
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snowlover2
post Jul 19 2018, 04:40 PM
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Marshalltown IA getting destroyed possibly.

QUOTE
BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Des Moines IA
437 PM CDT THU JUL 19 2018

...TORNADO EMERGENCY FOR MARSHALLTOWN...

The National Weather Service in Des Moines has issued a

* Tornado Warning for...
Eastern Marshall County in central Iowa...
Southwestern Tama County in central Iowa...

* Until 500 PM CDT.

* At 437 PM CDT, a confirmed large and destructive tornado was
observed over Marshalltown, moving east at 25 mph.

TORNADO EMERGENCY for Marshalltown. This is a PARTICULARLY
DANGEROUS SITUATION. TAKE COVER NOW!

HAZARD...Deadly tornado.

SOURCE...Law enforcement confirmed tornado.

IMPACT...You are in a life-threatening situation. Flying debris
may be deadly to those caught without shelter. Mobile
homes will be destroyed. Considerable damage to homes,
businesses, and vehicles is likely and complete
destruction is possible.

* The tornado will be near...
Meskwaki Casino around 500 PM CDT.

Other locations impacted by this tornadic thunderstorm include
Garwin, Gilman, Le Grand, Ferguson, Green Mountain, Montour,
Marshalltown Municipal Airport, Toledo Municipal Airport and Albion.


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

# of T-Storm Warnings:4

# of Tornado Watches:3

# of Tornado Warnings:1
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FireworkWX03
post Jul 19 2018, 05:02 PM
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QUOTE(snowlover2 @ Jul 19 2018, 01:44 PM) *
New day 2 has an expansion of the enhanced area although somewhat surprised it's not more north. 12z NAM shows a line of intense looking storms tomorrow night moving through most of IN/OH. Might see it shift north tonight on new day 1 if that continues.


The problem for Ohio is (surprise) mid-morning convection keeping things too stable. If it doesn't fire though, SW OH could get in on the action with the low track. Although the best forcing keeps trending further south. This is starting to look like a mid-South event moreso than anything here.

GFS does like us for late next week, but that's starting to get into fantasyland. Maybe we have a 2005-type severe weather season in store -- lots of nothing, some tail-end warm season events and an active fall season. Hope springs eternal!
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snowlover2
post Jul 19 2018, 05:12 PM
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QUOTE(FireworkWX03 @ Jul 19 2018, 06:02 PM) *
The problem for Ohio is (surprise) mid-morning convection keeping things too stable. If it doesn't fire though, SW OH could get in on the action with the low track. Although the best forcing keeps trending further south. This is starting to look like a mid-South event moreso than anything here.

GFS does like us for late next week, but that's starting to get into fantasyland. Maybe we have a 2005-type severe weather season in store -- lots of nothing, some tail-end warm season events and an active fall season. Hope springs eternal!

With this unexpected tornado outbreak in IA today, i'm not sleeping on anything tomorrow.


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

# of T-Storm Warnings:4

# of Tornado Watches:3

# of Tornado Warnings:1
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snowlover2
post Jul 19 2018, 05:30 PM
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Catastrophic damage in Marshalltown IA.

QUOTE
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE DES MOINES IA
505 PM CDT THU JUL 19 2018

..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..





0455 PM TORNADO 2 NW MARSHALLTOWN 42.05N 92.94W
07/19/2018 MARSHALL IA TRAINED SPOTTER

REPORTS OF CATASTROPHIC DAMAGE, INCLUDING
VEHICLES MISSING, VEHICLES OVERTURNED, TOPS
OF BUILDINGS GONE, TREES DOWN, POWER LINES,
GAS LINES, ETC...


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

# of T-Storm Warnings:4

# of Tornado Watches:3

# of Tornado Warnings:1
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WeatherMonger
post Jul 19 2018, 05:37 PM
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QUOTE(snowlover2 @ Jul 19 2018, 05:30 PM) *
Catastrophic damage in Marshalltown IA.

Wow, that is some decriptive storm report blink.gif
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WeatherMonger
post Jul 19 2018, 05:40 PM
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Wow, twin tornado in this vid



https://m.facebook.com/story.php?story_fbid...mp;id=501662735
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grace
post Jul 19 2018, 06:02 PM
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Iowa tornado video of it going through downtown Marshalltown:


https://twitter.com/BuzzFeedStorm/status/1020079627031625730

This post has been edited by grace: Jul 19 2018, 06:04 PM
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grace
post Jul 19 2018, 06:06 PM
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Another video in Bondurant, IA of what looks like a house imploding:


https://twitter.com/BuzzFeedStorm/status/1020071635817152512
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