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May 9, 2014 1630 UTC Day 1 Convective Outlook

May 9, 2014

May 9, 2014 1630 UTC Day 1 Convective Outlook

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DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1120 AM CDT FRI MAY 09 2014

VALID 091630Z – 101200Z

…THERE IS A SLGT RISK OF SVR TSTMS FROM THE OZARK PLATEAU INTO LOWER OH VALLEY…

…THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF TX…

…SUMMARY…
SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED OVER PARTS OF CENTRAL…SOUTHERN…AND EAST TEXAS TODAY. ELSEWHERE…A FEW SEVERE THUNDERSTORMS MAY OCCUR OVER PARTS OF THE OZARKS AND THE MID MISSISSIPPI AND OHIO VALLEYS.

…SYNOPSIS…

A BROAD CYCLONIC FLOW REGIME WILL BE MAINTAINED OVER THE CONUS THROUGH THE DAY ONE PERIOD TO THE SOUTH OF AN UPPER LOW WHICH WILL REMAIN ANCHORED OVER CNTRL CANADA. WITHIN THIS LARGE-SCALE REGIME…A SHORT-WAVE TROUGH COMPRISED OF MULTIPLE VORTICITY MAXIMA WILL TRANSLATE NEWD THROUGH THE UPPER GREAT LAKES…MID MS VALLEY AND OZARKS IN TANDEM WITH A 80 KT JET STREAK AT 500 MB WHICH WILL WEAKEN WHILE MOVING FROM THE OZARK PLATEAU INTO OH VALLEY. MEANWHILE…A LOWER-LATITUDE PERTURBATION WILL TRACK ACROSS NRN MEXICO INTO SRN TX. THESE DEVELOPMENTS WILL OCCUR DOWNSTREAM FROM A MIDLEVEL TROUGH WHICH WILL AMPLIFY OVER THE PACIFIC NW INTO NRN GREAT BASIN.

AT THE SURFACE…A COLD FRONT ASSOCIATED WITH THE N-CNTRL U.S. SHORT-WAVE TROUGH WILL ADVANCE EWD THROUGH THE GREAT LAKES WITH THE SEGMENT OVER THE OZARK PLATEAU REMAINING QUASI-STATIONARY. MEANWHILE…THE SWRN EXTENSION OF THE FRONT OVER THE SRN PLAINS WILL WEAKEN TODAY WITH THE PROMINENT SURFACE FEATURE BEING A DRYLINE WHICH WILL STRETCH FROM S-CNTRL/SERN OK SWWD INTO THE EDWARDS PLATEAU OF TX.

…TX TODAY INTO TONIGHT…

12Z SOUNDINGS SHOWED THE PRESENCE OF A VERY MOIST AIR MASS /LOWEST 100-MB MEAN-MIXING RATIOS OF 15-17 G PER KG/ SURMOUNTED BY AN EML CHARACTERIZED BY 700-500-MB LAPSE RATES OF 7.0-7.5 C/KM. THESE PARAMETERS WILL COMBINE WITH DAYTIME HEATING TO YIELD MODERATE TO STRONG AFTERNOON INSTABILITY TO THE SE OF THE DRYLINE WITH AFTERNOON MLCAPE APPROACHING 2000-3000 J/KG.

RELATIVELY WEAK CAPPING SHOWN ON THE 12Z DRT RAOB COUPLED WITH DCVA ATTENDANT TO THE SHORT-WAVE TROUGH MOVING OUT OF NRN MEXICO ARE EXPECTED TO SUPPORT A GRADUAL INCREASE IN TSTMS TODAY ACROSS THE EDWARDS PLATEAU INTO THE HILL COUNTRY AMIDST A KINEMATIC ENVIRONMENT FEATURING A VERTICALLY VEERING WIND PROFILE WITH 30-35 KT OF DEEP-LAYER. THE GIVEN SETUP WILL SUPPORT SUPERCELLS AND ORGANIZED MULTICELLS WITH A RISK FOR VERY LARGE HAIL AND DAMAGING WIND GUSTS. STORMS MAY EVENTUALLY GROW UPSCALE INTO CLUSTERS ALONG CONSOLIDATING OUTFLOWS WITH THE THREAT FOR DAMAGING WINDS AND LARGE HAIL CONTINUING THROUGH THE EVENING.

FOR ADDITIONAL NEAR-TERM GUIDANCE…SEE MCD 535 AND SEVERE THUNDERSTORM WATCH 134.

…OZARK PLATEAU INTO LOWER OH VALLEY THIS AFTERNOON INTO TONIGHT…

TSTMS HAVE RECENTLY DEVELOPED ALONG/S THE FRONT OVER CNTRL MO AS OF MID MORNING WITHIN A ZONE OF STRONGER FORCING FOR ASCENT/DCVA ASSOCIATED WITH THE SRN-MOST VORTICITY LOBE AND MIDLEVEL JET STREAK ATTENDING THE PARENT MIDLEVEL TROUGH. DAYTIME HEATING COUPLED WITH DEWPOINTS IN THE 60S SHOULD ALLOW FOR DOWNSTREAM AIR MASS TO FURTHER DESTABILIZE BY AFTERNOON WITH MLCAPE APPROACHING 1000-2000 J/KG. AND WHILE THE MIDLEVEL JET STREAK /MENTIONED IN THE SYNOPSIS/ WILL BE IN THE PROCESS OF WEAKENING…MORE THAN SUFFICIENT DEEP-LAYER SHEAR WILL EXIST FOR THE EVOLUTION OF SUPERCELLS AND/OR BOWING STRUCTURES BY AFTERNOON OVER E-CNTRL/SERN MO. EXPECT THIS ACTIVITY TO MOVE DEVELOP EWD/NEWD INTO PARTS OF THE LOWER OH VALLEY LATER THIS AFTERNOON INTO TONIGHT WITH THE PRIMARY HAZARDS BEING LARGE HAIL AND DAMAGING WIND GUSTS.

A SEPARATE CLUSTER OF TSTMS MAY DEVELOP THIS EVENING INTO THE OVERNIGHT HOURS INVOF OF THE STALLED FRONT OVER SRN MO/NRN AR AS FORCING FOR ASCENT IS ENHANCED BY A LOW-AMPLITUDE SHORT-WAVE TROUGH MOVING ACROSS KS/OK. SUFFICIENT INSTABILITY AND VERTICAL SHEAR WILL EXIST FOR ORGANIZED STORMS…INCLUDING SUPERCELLS WITH A RISK FOR LARGE HAIL AND DAMAGING WINDS.

…ARKLATEX INTO LOWER MS VALLEY…

MORNING OBSERVATIONS INDICATE THAT CONSIDERABLE OVERTURNING OF THE AIR MASS HAS OCCURRED WITH NOCTURNAL STORMS WHICH WILL LIKELY TEMPER THE DEGREE OF DESTABILIZATION THAT OCCURS THIS AFTERNOON. WHILE ISOLATED SEVERE STORMS REMAIN POSSIBLE ALONG RESIDUAL CONVECTIVE OUTFLOW BOUNDARIES…MORE ORGANIZED POTENTIAL APPEARS TO BE LIMITED. AS SUCH…THE CATEGORICAL SLIGHT RISK HAS BEEN REMOVED FROM SOME LOCATIONS.

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