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April 1-3 Severe Weather


Hoosier

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Looks like there could be some severe threats in this timeframe.

The day 3/Monday into Tuesday threat looks interesting to me. It doesn't have a slight risk right now but I think it will later. Shear magnitudes aren't all that great on the models but mid level lapse rates are very good and there is quite a bit of instability (12z NAM has MUCAPE of 2000-2500+ in parts of IL/IN at 6z Tuesday). Looks like at least a pretty decent hail threat in the Monday/Tuesday period.

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Slight risk for Sunday

day2otlk_20120331_1730_prt.gif

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1227 PM CDT SAT MAR 31 2012

VALID 011200Z - 021200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE OH

VALLEY...

...OH VALLEY...

NORTHWEST FLOW WILL BE IN PLACE ACROSS THE NERN STATES SUNDAY WITH A

SHORTWAVE TROUGH MOVING SEWD ACROSS THE ERN GREAT LAKES DURING THE

DAY. AT THE SFC...A COLD FRONT SHOULD MOVE SWD INTO THE OH VALLEY

DURING THE AFTERNOON WITH AN AXIS OF MODERATE INSTABILITY DEVELOPING

FROM WRN KY NEWD ACROSS IND INTO WRN OH. SOME CONVECTION MAY BE

ONGOING ACROSS THE LOWER OH VALLEY SUNDAY MORNING WITH NEW

CONVECTION DEVELOPING ALONG AND AHEAD OF THE FRONT FROM CNTRL IND

SEWD ACROSS SRN OH. MODEL FORECASTS MOVE THIS CONVECTION SWD ACROSS

KY AND WV DURING THE LATE AFTERNOON AND EVENING.

A 75 TO 85 KT MID-LEVEL JET ASSOCIATED WITH THE SHORTWAVE TROUGH

OVER ERN GREAT LAKES WILL MOVE SEWD INTO THE CNTRL APPALACHIAN MTNS

SUNDAY WITH THE SERN EDGE OF THE JET AFFECTING THE OH VALLEY. THIS

WILL CREATE MODERATE TO STRONG DEEP LAYER SHEAR PROFILES ACROSS THE

SLIGHT RISK AREA. IN ADDITION...FORECAST SOUNDINGS BY MID-AFTERNOON

SHOW A MODERATELY UNSTABLE AIRMASS IN PLACE ACROSS SRN IND...SW OH

AND MOST OF KY WITH MUCAPE IN THE 1000 TO 1500 J/KG RANGE. THIS

COMBINED WITH STEEP MID-LEVEL LAPSE RATES MAY BE SUFFICIENT FOR

SUPERCELLS WITH LARGE HAIL IF CELLS CAN REMAIN DISCRETE. IF

SUPERCELLS CAN ORGANIZE...THEN AN ISOLATED TORNADO THREAT MAY EXIST

AS WELL. HOWEVER...THE DOMINANT CONVECTIVE MODE FOR SUNDAY REMAINS

UNCERTAIN AT THIS TIME AND FRONTAL FORCING COULD ENCOURAGE THE

DEVELOPMENT OF A LINE POSING A WIND DAMAGE THREAT.

...UPPER MS VALLEY...

AN UPPER-LEVEL RIDGE WILL MOVE EWD ACROSS THE GREAT PLAINS INTO THE

MS VALLEY ON SUNDAY. AT THE SFC...A MOIST AXIS SHOULD BE LOCATED

FROM THE MID MO VALLEY NWD INTO SRN MN WHERE MODERATE INSTABILITY

SHOULD EXIST BY EARLY SUNDAY EVENING. LATER ON SUNDAY

EVENING...MODEL FORECASTS INITIATE THUNDERSTORMS ALONG THE NRN EDGE

OF THE INSTABILITY AXIS AS A COLD FRONT ADVANCES SEWD INTO THE UPPER

MS VALLEY. FORECAST SOUNDINGS JUST AHEAD OF THE FRONT LATE SUNDAY

EVENING SHOW ELEVATED INSTABILITY WITH MUCAPE IN THE 1000 TO 1500

J/KG RANGE AND CLOUD LAYER SHEAR OF 40 TO 45 KT. THIS COULD SUPPORT

A MARGINAL HAIL THREAT WITH THE STRONGER CORES WITH THREAT

PERSISTING INTO THE OVERNIGHT PERIOD.

..BROYLES.. 03/31/2012

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Regarding tomorrow night, very pronounced veering profiles with height although mid/upper level flow still pretty anemic.  Instability parameters continue to look good.  May be tough to get sustained supercells but hail threat still looking good whether multicellular or supercellular and maybe some damaging wind potential if an organized MCS can evolve.  Euro continues to keep everything farther north but NAM/GFS have been insistent on convection spilling southeastward from WI.

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Rinse and repeat, same as yesterday. Again summer looking pattern Thermal heat axis Mid-level shortwave riding SE. Hail and locally damaging straight line wind threat. It appears to be setting up further north though...

I didn't know you were on here :P

Welcome to the board :)

Yes - other than the big end of February outbreak and the beginning of March - it seems like it has been a slow severe season. Granted there were some big big numbers with those outbreaks. It has basically been fairly quiet since. A few hailers.

Will be curious how the rest of April goes. These temperatures are amazing. Stunning!

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The lapse rates aloft are a big factor. Very rapid temp drop with height.

Thanks, I also notice they expect the warm frontal position to be in far N Iliinois, meaning higher cape values just to the south in the Chicago area, but we're probably a tad too far north for good CAPE values here.

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SPC going with a large 5% risk area on Tuesday. Will likely see a SLIGHT RISK at some point somewhere in that massive area.

SPC says: ...NRN IL INTO THE OH VALLEY...

AS THE UPPER TROUGH GLANCES THE AREA...CONVERGENCE WILL INCREASE NEAR A W-E ORIENTED FRONT FROM NRN IL INTO WRN OH. DAYTIME HEATING AND DEWPOINTS IN THE LOWER 60S F WILL LEAD TO SUBSTANTIAL INSTABILITY AND STORMS ARE LIKELY LATE IN THE DAY AND INTO THE EVENING. INITIAL ACTIVITY IS EXPECTED OVER WRN PORTIONS OF THE AREA WHERE FLOW ALOFT WILL BE WEAK. BUT...WITH TIME...ACTIVITY MAY CONSOLIDATE INTO ONE OR MORE MCS'S PROPAGATING S AND SEWD CAPABLE OF LOCALLY STRONG TO SEVERE WINDS AND PERHAPS SOME HAIL.

post-5115-0-58812000-1333350286.gif

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SPC still going with a very large 5% risk area. They did extend that risk area north too include the Great Lakes region.

Basically the same discussion as before except for one important snippet at the end...

...NRN IL INTO THE OH VALLEY...

AS THE UPPER TROUGH GLANCES THE AREA...CONVERGENCE WILL INCREASE NEAR A W-E ORIENTED COLD FRONT FROM NRN IL INTO WRN OH. DAYTIME HEATING AND DEWPOINTS IN THE LOWER 60S F WILL LEAD TO MODERATE INSTABILITY AND STORMS WILL LIKELY DEVELOP LATER IN THE DAY AND INTO THE EVENING. INITIAL ACTIVITY IS EXPECTED OVER WRN PORTIONS OF THE AREA WHERE FLOW ALOFT WILL BE WEAK. BUT...WITH TIME...ACTIVITY MAY CONSOLIDATE INTO ONE OR MORE MCS'S PROPAGATING S AND SEWD CAPABLE OF LOCALLY STRONG TO SEVERE WINDS AND PERHAPS SOME HAIL. THIS AREA WILL BE MONITORED FOR A POSSIBLE SLIGHT RISK IN DAY 1 UPDATES.

post-5115-0-44369500-1333389633.gif

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Pulse storm setup for your area Patrick. It looks like good lapse rates and instability for this evening but no deep layer shear to speak of. It could be one of those where a storm goes from nothing to severe within three radar scans, drops some quarters, and create isolated wind damage as it dies. Might be an MCS roll across southern IN though.

EDIT: Hoosier, I saw your post from yesterday right after I posted this. At least I know that you agree with me.

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MD issued for my neck of the woods. I know the big action is in TX but looks like we could get something today.

MESOSCALE DISCUSSION 0433

NWS STORM PREDICTION CENTER NORMAN OK

0217 PM CDT TUE APR 03 2012

AREAS AFFECTED...NERN MO...CNTRL IL...FAR WRN IND

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 031917Z - 032045Z

LARGE HAIL AND DAMAGING WIND GUSTS WILL BE POSSIBLE WITH STORMS

FORMING THIS AFTERNOON/EVENING OVER NERN MO...CNTRL IL AND FAR WRN

IND. TRENDS WILL CONTINUE TO BE MONITORED FOR POSSIBLE WW.

SURFACE ANALYSIS AT 18-19Z PLACED AN AREA OF LOW PRESSURE OVER NRN

PORTIONS OF CNTRL IL...WITH A COLD FRONT EXTENDING SWWD INTO CNTRL

MO AND A WARM FRONT LOCATED SEWD INTO ERN IL AND SRN IND. WARM

SECTOR AIRMASS BETWEEN THESE TWO FRONTS IS CHARACTERIZED BY

TEMPERATURES IN THE 80S AND DEWPOINTS FROM THE MID/UPR 50S TO LOW

60S. RUC OBJECTIVE ANALYSIS GUIDANCE ALSO SHOWS THE PRESENCE OF

STEEP 700-500 MB LAPSE RATES /FROM 7 TO 8 C PER KM/...WHICH WILL AID

IN MLCAPE VALUES NEAR 1500 J/KG WITH A FEW MORE HRS OF SURFACE

HEATING. UPSTREAM FROM THE REGION...A MIDLEVEL VORTICITY LOBE IS

MOVING NEWD ACROSS CNTRL MO. LARGE-SCALE ASCENT ASSOCIATED WITH THIS

FEATURE COMBINED WITH CONVERGENCE AND DESTABILIZATION ALONG BOTH THE

COLD AND WARM FRONTAL BOUNDARIES SHOULD AID IN SCATTERED

THUNDERSTORM DEVELOPMENT BY 20-22Z. AREA VWP/S AND RUC SOUNDINGS

INDICATE VERTICAL SHEAR PROFILES WILL BE MARGINALLY SUPPORTIVE FOR

ORGANIZED MULTICELL CLUSTERS AND LINE SEGMENTS. HOWEVER...THE

MODERATE CAPE/STEEP LAPSE RATE ENVIRONMENT WILL SUPPORT A THREAT FOR

LARGE HAIL AND DAMAGING WIND GUSTS.

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first towers of the day going up in central IL. Looking at the RUC projection on SPC Mesoanalysis, it looks like the front is sagging south rather quickly and severe prospects are probably minimal north of LAF.

Yep. IWX mentioned this in their afternoon disco. Looks like the hailers will be south of MBY and LAF.

HWVR LOCALLY XPC LTL IN WAY OF ADDNL SHRA/TSRA GOING FORWARD ESP IN

LIGHT OF RUC/HIGHRES GUIDANCE ADVTG LK SHADOW QUICKLY INLAND LT THIS

AFTN/EVE AS MID LVL CONFLUENCE ZONE SHIFTS SWD IN RESPONSE TO NRN

STREAM SW TROUGH AMPLIFYING SEWD INTO WRN QB. CONCURRENT SWD SHIFT

OF SFC TROUGH/OUTFLW AND DEEPENING NRLY FLW CERTAINLY DOES NOT BODE WELL

BUT GIVEN LAGGING H85 BNDRY AND APPRECIABLE THETA-E PLUME WILL HOLD

W/LOW CHC POPS ACRS IN/OH THIS EVENING BFR TRUNCATING FURTHER LT

TONIGHT.

Already have a warning for possible quarters in Livingston Co. It will be interesting to see if these storms pulse or we get an MCS out of them.

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Already have a warning for possible quarters in Livingston Co. It will be interesting to see if these storms pulse or we get an MCS out of them.

Good comment. If the possible MCS forms it will probably move se from north central IL as anticipated.

74/56 here with se wind so boundary is just to the north.

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