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March 27-28 Severe Weather Potential


Hoosier

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52/35 at PIA at 10a.m. Central time. We got a ways to go. But t storms are initiating west of KC and more importantly, dews are advecting northward in the 55-60 range in western MO at this hour.Stage is being set. Current low level helicity values are through the roof in areas of possible concern for this evening. Warm front and cold fronts may be in play as Justin emphasized.

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Still hoping for a brief window of opportunity late this afternoon/early this eve. Many of the models blow up some scattered convection right along the Mississippi around 00z. The RUC forecast of 2000j/kg cape is nice to look at, but unrealistic given the amount of mixing that will take place this afternoon. Should still be a narrow corridor of 1000-1300j/kg cape in an area where hodos are still pretty respectable. Just gonna sit at home and wait and see how it evolves, and then head out when things become more clear.

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Anybody noticed the "Trends/Forecast" section that has been added to the SPC mesoanalysis pages? Now you can see the last 4 hours of observed data, plus the next 6 hours of forecast data using the RUC, just by scrolling over the hours.

Very cool new feature.

Yeah very nice feature to be sure. I really like the side by side zero hour comparison of observed values versus what the RUC is initializing.

With that being said the extrapolation of the RUC shows pockets of sig tor values of 2 in western Illinois early this eve.

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Anybody noticed the "Trends/Forecast" section that has been added to the SPC mesoanalysis pages? Now you can see the last 4 hours of observed data, plus the next 6 hours of forecast data using the RUC, just by scrolling over the hours.

Very cool new feature.

I just discovered and played around with it this morning. Very helpful new feature.

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Anybody noticed the "Trends/Forecast" section that has been added to the SPC mesoanalysis pages? Now you can see the last 4 hours of observed data, plus the next 6 hours of forecast data using the RUC, just by scrolling over the hours.

Very cool new feature.

I noticed this as well today, I certainly like the feature.

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MESOSCALE DISCUSSION 0367

NWS STORM PREDICTION CENTER NORMAN OK

0358 PM CDT TUE MAR 27 2012

AREAS AFFECTED...EASTERN IA/SOUTHERN WI/NORTHWEST IL/NORTHEAST MO

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 272058Z - 272300Z

MONITORING FOR AN INCREASING SEVERE THREAT...WHICH COULD INITIALLY OCCUR ACROSS PORTIONS OF THE REGION INTO THE 23Z-02Z TIME FRAME. A WATCH MAY BE NEEDED THIS EVENING.

A WEAK COLD FRONT CONTINUES TO MAKE A GRADUAL EASTWARD PROGRESSION TOWARD THE UPPER MS RIVER VALLEY AT MID AFTERNOON WITHIN A NORTHEAST-SOUTHWEST ORIENTED CORRIDOR FROM WESTERN WI TO SOUTH-CENTRAL IA/NORTHWEST MO. MODEST LOW-LEVEL MOISTURE...WITH SURFACE DEWPOINTS GENERALLY IN THE 50S F...OTHERWISE CONTINUES TO STEADILY INCREASE WITH NORTH-NORTHEASTWARD EXTENT IMMEDIATELY AHEAD OF THE FRONT. NEAR/AHEAD OF THIS FRONT...LOW-LEVEL CONVERGENCE REMAINS MODEST AS WINDS AT/JUST ABOVE THE SURFACE HAVE CONTINUED TO VEER PER SURFACE OBSERVATIONS/REGIONAL DERIVED WIND DATA. HOWEVER...A LOW-AMPLITUDE EASTWARD-MOVING SHORTWAVE TROUGH/SPEED MAX CURRENTLY OVER SD/SOUTHWEST MN PER WATER VAPOR IMAGERY MAY PROVIDE AN IMPETUS FOR AT LEAST ISOLATED DEEP CONVECTIVE DEVELOPMENT OVER THE NEXT FEW HOURS...AS INHIBITION OTHERWISE CONTINUES TO ERODE WITHIN THE MODESTLY MOIST NEAR-FRONTAL WARM SECTOR.

WHILE CONFIDENCE IN CONVECTIVE DETAILS ARE NOT PARTICULARLY HIGH...AN ASSORTMENT OF NUMERICAL GUIDANCE INCLUDING A NUMBER OF 15Z SREF MEMBERS IMPLY THAT SUCH DEVELOPMENT WILL BE MORE PROBABLE INTO THE 23Z-02Z TIME FRAME ESPECIALLY ACROSS FAR EASTERN IA/FAR NORTHWEST IL AND ADJACENT PARTS OF NORTHERN MO...ALTHOUGH A GRADUAL DEEPENING OF THE CUMULUS FIELD HAS BEEN NOTED AS FAR NORTHEAST AS SOUTHWEST WI AT MID-AFTERNOON. IF/WHERE DEEP CONVECTIVE DEVELOPMENT DOES OCCUR INTO THIS EVENING...STRONG EFFECTIVE SHEAR /45-50 KT OR GREATER/ WILL SUPPORT ORGANIZED/SUSTAINED STORMS INCLUDING INITIAL MODE SUPERCELLS CAPABLE OF SEVERE HAIL/PERHAPS A TORNADO...WITH DAMAGING WINDS A POSSIBILITY AS WELL. CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED FOR A POSSIBLE WATCH.

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Dewpoints are in the mid-40s up in this area. I wouldn't expect much in the way of severe weather up this way. If something is going to pop I would think it would be pretty soon, were going to loose the day time heating.

Looks like something trying to get going near Princeton, IL.

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MESOSCALE DISCUSSION 0370

NWS STORM PREDICTION CENTER NORMAN OK

0843 PM CDT TUE MAR 27 2012

AREAS AFFECTED...PORTIONS NRN/WRN IL...EXTREME NERN/N-CENTRAL

KS...EXTREME NWRN INDIANA...WRN/NRN MO...EXTREME SERN IA...EXTREME

SRN LM.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 280143Z - 280345Z

GRADUAL DEEPENING OF CONVECTION HAS BEEN NOTED IN PREFRONTAL BAND

FROM N-CENTRAL IL TO NERN MO...WITH POTENTIAL MOVEMENT ACROSS SRN LM

REGION AND POSSIBLE BACKBUILDING TOWARD KS/MO BORDER REGION DURING

NEXT FEW HOURS. OCNL SVR HAIL OR DAMAGING GUSTS ARE POSSIBLE.

01Z SFC MESOANALYSIS SHOWED COLD FRONT FROM E-CENTRAL WI SWWD ACROSS

DBQ/OTM/STJ AREAS. WARM FRONT WAS DRAWN FROM ERN WI SSEWD ACROSS

CHI AREA TO NEAR SDF...HOWEVER RELATIVELY DRY SFC AIR WITH MID-UPPER

40S F DEW POINTS EXTENDED W OF WARM FRONT OVER ERN IL. GIVEN SWLY

FLOW ON BOTH SIDES OF COLD FRONT...FRONTAL CONVERGENCE WAS

WEAK...AND SHOULD REMAIN SO THROUGH AT LEAST 04Z. HOWEVER...SFC

CONFLUENCE LINE WAS EVIDENT OVER W-CENTRAL/N-CENTRAL IL. THOUGH AT

OBLIQUE ANGLE TO DEVELOPING CONVECTION...STRONGEST LOW-LEVEL LIFT

APPEARS TO BE NEAR SFC CONFLUENCE ZONE. MOIST AXIS WAS DRAWN ABOUT

35-45 NM AHEAD OF FRONT OVER MOST OF AREA. 850 AND 925 MB UPPER AIR

CHARTS SHOWED MOIST AXES AT THOSE LEVELS NEARLY COLLOCATED FROM

PNC-MKC-PIA. 00Z UPPER AIR CHARTS AND LATEST VWP/PROFILER WINDS

INDICATED LLJ AXIS SLIGHTLY FARTHER S NEAR OKC-COU-SBN LINE.

CONVECTION HAS DEVELOPED AHEAD OF FRONT...ALONG SRN FRINGE OF

LOW-LEVEL MOIST PLUME...S OF MOIST AXES AND N OF LLJ. MOIST

ADVECTION...AND INCREASING ISENTROPIC ASCENT...SHOULD HELP TO

MAINTAIN THIS ACTIVITY AND PERHAPS INCREASE COVERAGE...WHILE BAND

TRANSLATES EWD 20-25 KT AND EMBEDDED CELLS MOVE FASTER NEWD.

MODIFIED DVN/ILX/TOP/SGF RAOBS...ORD ACARS SOUNDING AND RUC FCST

SOUNDINGS SUGGEST 1000-1500 J/KG MLCAPE NEAR MOIST AXIS...BUT ALSO

INCREASING MLCINH LIKELY WITH EVENING DIABATIC COOLING NEAR SFC.

THIS WILL MAKE DAMAGING WIND POTENTIAL MORE CONDITIONAL/MRGL WITH

TIME. MEANWHILE NEARLY PARALLEL NATURE OF MEAN FLOW TO CONVECTIVE

PLUME SUPPORTS QUASI-LINEAR CONVECTIVE MODE...LIKELY LIMITING THREAT

FOR SIGNIFICANT SVR HAIL. NONETHELESS...PRESENCE OF FAVORABLE

BUOYANCY ATOP MOISTURE PLUME...AND EFFECTIVE SHEAR MAGNITUDES

RANGING FROM AROUND 50 KT OVER NRN IL TO 35 KT NEAR MKC...WILL

SUPPORT SOME POTENTIAL FOR ORGANIZED CONVECTION WITH SPORADIC SVR.

THREAT SHOULD DIMINISH SEWD OVER E-CENTRAL IL AND NRN INDIANA INTO

PROGRESSIVELY WEAKER LOW-LEVEL THETAE.

..EDWARDS.. 03/28/2012

ATTN...WFO...LOT...ILX...LSX...DVN...DMX...EAX...TOP.

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