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2015 Short Term Severe Weather Discussion

Hoosier

By Hoosier,
in Lakes/Ohio Valley

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Stebo

Stebo

Posted
Posted

IWX: ATTENTION THEN TURNS TO PRECIP CHANCES WEDNESDAY AFTERNOON/NIGHT.

SHARP/DIGGING UPPER SHORTWAVE WILL TRACK FROM THE NRN TIER INTO THE

WRN GREAT LAKES BY WEDNESDAY AFTERNOON...AS STRONG 110 KT UPPER JET

ROUNDS THE BASE OF THIS TROF. RESULTANT DEEPENING SFC LOW ACROSS THE

GREAT LAKES WILL PUSH A STRONG FRONT EAST THROUGH THE AREA MONDAY

AFTERNOON AND EVENING(???). ALTHOUGH A BIT FAR OUT FOR

DETAILS...INCREASED SEVERE CHANCES MAY BE POSSIBLE DEPENDING ON

TIMING OF FROPA AND EVOLUTION OF STORMS...ALTHOUGH MID LEVEL LAPSE

RATES LOOK POOR AT THIS POINT. WILL DEFINITELY BE A FEATURE TO KEEP

AN EYE ON OVER THE NEXT SEVERAL DAYS.

 

ILX: THE 12Z GFS HAS SPED UP THIS SYSTEM AND

NOW IS MORE IN LINE WITH LAST NIGHT'S ECMWF BRINGING THE BEST

CHANCES OF PRECIP TO ILLINOIS WEDNESDAY. BETTER DYNAMICS WITH THIS

MID-WEEK SYSTEM SUGGESTS BETTER FORCING AND 0-6 KM SHEAR VALUES

SUFFICIENT FOR ORGANIZED CONVECTION. WITH THE HIGH BOUNDARY LAYER

HUMIDITY LEADING TO SOME DECENT INSTABILITY, WEDNESDAY AND WEDNESDAY

NIGHT WILL NEED TO BE WATCHED WITH REGARDS TO POTENTIAL OF SEVERE

WEATHER.

 

GRR: MODELS ARE IN FAIRLY GOOD AGREEMENT ON SHOWING A VIGOROUS MID LEVEL

WAVE ARRIVING FOR THE MIDDLE OF NEXT WEEK. BASED ON THE STRENGTH OF

THE WINDS AN ELEVATED RISK FOR SEVERE WEATHER EXISTS. MESOSCALE

FEATURES ALTER TIMING STRENGTH AND LOCATION OF ANY CONVECTION. WILL

FEATURE THE HIGHEST POPS FOR THE MIDDLE PART OF THE WEEK DUE TO

THIS PASSING WAVE.

 

LMK: THE POSSIBILITY OF A FROPA WEDNESDAY NIGHT OR THURSDAY IS A SOMEWHAT

NEW IDEA WITH THE OPERATIONAL GFS, THOUGH THE MODEL HAS SHOWN A

TREND TOWARD THIS SOLUTION OVER ABOUT THE PAST THREE RUNS. THE ECMWF

AND GEFS MEAN DON'T QUITE GO ALONG WITH THIS SCENARIO, THOUGH, AND

THE GEFS PLUME DIAGRAM SHOWS ONLY A HANDFUL OF INDIVIDUAL MEMBERS

WITH SIGNIFICANT RAINFALL DURING THAT TIME FRAME.

With respect to IWX there is a front that is weakening coming through on Monday, ahead of the Wednesday system.

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Geos

Geos

Posted
Posted

Was outside, had no idea there was any action until breeze picked up and we got a little outflow, no idea what the temp was but it felt like 30 degrees. Dry so far but the system looks to have started a little side action to the west over Janesville, might get lucky and get a little something if it holds together.

Sent from my iPhone

 

Drifting southwards to you.

 

LOT.N0Q.20150815.0332.gif

 

Further southeast.

 

IWX.N0Q.20150815.0324.gif

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CanadianGuy

CanadianGuy

Posted
Posted

Sub 990mb low on the 06z GFS. Trailing cold front is impressive for any time of year, but especially for August. Other models are hopping on board including the Canadian, Euro, and NAVGEM.. but timing and strength of the system are vastly different between the four. 

 

EDIT: Someone might want to start a thread soon. 

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geddyweather

geddyweather

Posted
Posted

Shaping up to be an interesting mid August event here...

 

 

day4prob.gif?1439657383796

day5prob.gif?1439657397355

 

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0403 AM CDT SAT AUG 15 2015

VALID 181200Z - 231200Z

...DISCUSSION...
LATEST RUNS OF THE MEDIUM-RANGE MODELS ARE EXHIBITING FAIRLY GOOD
MODEL-TO-MODEL CONSISTENCY THROUGH ROUGHLY DAY 5 /WED. AUG.
19/...DEPICTING THE DEVELOPMENT AND NEWD PROGRESSION OF A SURFACE
LOW FROM THE CENTRAL HIGH PLAINS AT THE START OF DAY 4 /12Z 8-18/ TO
THE IA/WI VICINITY AT THE START OF DAY 5 /12Z 8-19/. THIS IS
PROGGED TO OCCUR IN RESPONSE TO A MID-LEVEL TROUGH WHICH CONTINUES
TO DIG SEWD OUT OF THE ROCKIES AND INTO THE PLAINS THROUGH THE DAY 4
PERIOD.

AS THE TRAILING SURFACE COLD FRONT SWEEPS ACROSS THE CENTRAL PLAINS
IN THE WAKE OF THE PROGRESSING LOW...SHOWERS AND THUNDERSTORMS ARE
FORECAST IN A NW-SE BAND ACROSS THE CENTRAL CONUS...WITH THE
CAPE/SHEAR ENVIRONMENT INVOF THE FRONT LIKELY TO BE SUPPORTIVE OF
STRONG/LOCALLY SEVERE STORMS...AND ASSOCIATED HAIL/WIND RISK.

DAY 5...THE UPPER TROUGH IS FORECAST TO TAKE ON A NEGATIVE TILT WITH
TIME...EJECTING NEWD INTO THE UPPER GREAT LAKES REGION WHILE THE
ASSOCIATED SURFACE LOW CROSSES THE GREAT LAKES AND SHIFTS INTO
ONTARIO WITH TIME. AGAIN...SHOWERS AND STORMS ARE FORECAST ALONG
THE TRAILING PORTION OF THE COLD FRONT FROM THE GREAT LAKES SWWD TO
TX...WITH AMPLE SHEAR EXPECTED FROM ROUGHLY THE ARKLATEX NEWD ALONG
THE FRONT TO SUPPORT SCATTERED SEVERE STORMS WITH HAIL/WIND
POTENTIAL.

DAY 6...MODELS DEPICT THE INITIAL/GREAT LAKES TROUGH SHIFTING NEWD
INTO CANADA...SUGGESTING MORE LIMITED/ISOLATED RISK INTO THE NERN
STATES. UNCERTAINTY IS GREATER HOWEVER ACROSS THE W FROM DAY 6
ONWARD DUE TO THE DIFFERENCES WITH RESPECT TO THE NEXT TROUGH
EVOLVING OVER THE ROCKIES. GIVEN THIS UNCERTAINTY...NO RISK AREAS
WILL BE HIGHLIGHTED BEYOND DAY 5 ATTM.

 

 

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ClicheVortex2014

ClicheVortex2014

Posted
Posted

Dr. Forbes' latest

 

TUESDAY
Severe thunderstorms in south MN, central and south WI, north and west IL, IA, southeast NE, northwest MO, east KS, northwest and north-central OK, TX panhandle. TORCON - 4 southeast MN, southwest WI, northwest IL, east IA; 2 to 3 rest of area
LGS21Zd.jpg
 
WEDNESDAY
Severe thunderstorms along and ahead of a cold front in an area from MI and the Midwest to the Mid-South to the Southern Plains. Computer models vary in the details, so only a general outline has been given for now with a TORCON of 2 to 3

17ZpvpK.jpg

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Quincy

Quincy

Posted
Posted

Tuesday might feature a decent threat on the western edge of this subforum, but the models taken verbatim at this point are fairly underwhelming for Wednesday. The latest GFS shows poor mid-level lapse rates, marginal shear (20-30kts) and a unidirectional shear pattern. There's nothing stopping a squall line from developing with isolated to scattered wind damage, but the tor/hail threats appear marginal at best.

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IWXwx

IWXwx

Posted
Posted

It must be this Godzilla El Nino  :rolleyes:

 

I read that some are calling it the Bruce Lee El Nino. There is actually an argument over what to call it. 

 

Tuesday might feature a decent threat on the western edge of this subforum, but the models taken verbatim at this point are fairly underwhelming for Wednesday. The latest GFS shows poor mid-level lapse rates, marginal shear (20-30kts) and a unidirectional shear pattern. There's nothing stopping a squall line from developing with isolated to scattered wind damage, but the tor/hail threats appear marginal at best.

 

The shear issues are obviously common this time of year, but it seems that the lapse rates have been a problem all year in this area.

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Stebo

Stebo

Posted
Posted

I'd say that synoptic setup trumps mesoscale details and timing issues this far out. Mid August with a strong synoptic system probably means trouble somewhere in the region on one or both of the days.

Yeah I wouldn't get too hung up on the mesoscale this far out especially with Tuesday looking pretty good out over the plains, that will likely modulate the system for the region with unforeseen effects, especially if a strong MCS forms out there and tracks toward the region.

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Quincy

Quincy

Posted
Posted

I'd say that synoptic setup trumps mesoscale details and timing issues this far out. Mid August with a strong synoptic system probably means trouble somewhere in the region on one or both of the days.

While it's interesting to note a few significant tornado events per analogs in Indiana, overall severe reports are fairly sparse for similar setups in the past. That Indiana event was 9/20/02 and more of a "typical" early fall event with a deeper, somewhat more amplified trough than is forecast by current guidance. Either way, leave out that day from the analogs and the Wednesday setup, assuming there are no major changes, looks relatively unimpressive. The severe PPF maps don't even delineate a 15% severe risk - not to say that such a risk won't be warranted. 

post-533-0-94488100-1439687472_thumb.png

 

The Tuesday event looks better in terms of both guidance and analogs, favoring the central Plains to Iowa vicinity. It's still several days out though and timing can have an impact on the geographic area and perhaps to a lesser extent, spatial coverage/intensity.

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RCNYILWX

RCNYILWX

Posted
Posted

While it's interesting to note a few significant tornado events per analogs in Indiana, overall severe reports are fairly sparse for similar setups in the past. That Indiana event was 9/20/02 and more of a "typical" early fall event with a deeper, somewhat more amplified trough than is forecast by current guidance. Either way, leave out that day from the analogs and the Wednesday setup, assuming there are no major changes, looks relatively unimpressive. The severe PPF maps don't even delineate a 15% severe risk - not to say that such a risk won't be warranted.

attachicon.gifSVRgfs212F108.png

The Tuesday event looks better in terms of both guidance and analogs, favoring the central Plains to Iowa vicinity. It's still several days out though and timing can have an impact on the geographic area and perhaps to a lesser extent, spatial coverage/intensity.

That was my primary point, not to discount what you posted at all, as obviously it will be an important detail as we get closer to the event. Hopefully this trough produces some interesting weather. Will be doing long term forecast for LOT tomorrow, so I'll be able to dig into things in more detail. It does look like a case where warm frontal zone could potentially be interesting even with eastward extent.
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ClicheVortex2014

ClicheVortex2014

Posted
Posted

It seems like when you get these stronger systems, the threat tends to be highest on day 1... probably mostly because of leftover rain/debris clouds caused by the stronger forcing.

 

We haven't had many days with the severe threat dependent on the sun peaking out this year... big change from last year when it seemed like every event was like that. I really don't want to go back to those days but ugh... that's the price you pay for living in this area.

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Gilbertfly

Gilbertfly

Posted
Posted

Stronger systems pull on into the upper GL...doesn't leave as much synopitcly downstream the following days

Still liking the slower timing....a tad slower than has been averaged out across the suite the last 48...synoptic is the key...details to come, but synoptics seems to find a way to win in the end

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