18z Supplemental Info
Still around 18z, when the following mesoscale discussions are released by SPC:
MD #5
MESOSCALE DISCUSSION 5[FONT="]
[/FONT]NWS STORM PREDICTION CENTER NORMAN OK[FONT="]
[/FONT]1229 PM CDT[FONT="]
[/FONT]AREAS AFFECTED...SERN OK...NERN TX...NRN LA...NRN MS AND SWRN AR[FONT="]
[/FONT]CONCERNING...SEVERE THUNDERSTORM POTENTIAL [FONT="]
[/FONT]VALID 1729Z - 2030Z[FONT="]
[/FONT]STORMS ARE EXPECTED TO DEVELOP ALONG/N OF WARM FRONT IN ARKLATEX[FONT="]
[/FONT]REGION THIS AFTERNOON AS WELL AS FARTHER E INTO SRN/CNTRL MS. TIMING[FONT="]
[/FONT]OF INITIATION IS STILL UNCERTAIN...BUT ONCE STORMS[FONT="]
[/FONT]DEVELOP...SUPERCELLS WILL BE LIKELY. LARGE HAIL AND ISOLATED[FONT="]
[/FONT]DAMAGING WIND APPEAR TO BE THE MAIN THREATS. HOWEVER...AN ISOLATED[FONT="]
[/FONT]TORNADO OR TWO WILL ALSO BE POSSIBLE.[FONT="]
[/FONT]SURFACE DATA SHOW A WARM FRONT FROM SRN MS WNWWD THROUGH NRN LA INTO[FONT="]
[/FONT]NERN AND N CNTRL TX. RICH LOW LEVEL MOISTURE...SURFACE HEATING AND[FONT="]
[/FONT]STEEP LAPSE RATES ARE SUPPORTING DESTABILIZATION ALONG AND S OF THE[FONT="]
[/FONT]BOUNDARY WITH MLCAPES ALREADY FROM 2000 TO 2500 J/KG. LATEST VISIBLE[FONT="]
[/FONT]DATA SHOW CUMULUS CONTINUES TO INCREASE IN THE VICINITY OF THE[FONT="]
[/FONT]BOUNDARY. THE ATMOSPHERE STILL APPEARS CAPPED NEAR THE BOUNDARY...[FONT="]
[/FONT]AND THIS IN CONJUNCTION WITH UPPER RIDGING MAY DELAY SURFACE BASED[FONT="]
[/FONT]INITIATION ANOTHER 1-2 HOURS. LOW LEVEL JET SHOULD STRENGTHEN OVER[FONT="]
[/FONT]THE SRN PLAINS INTO THE AFTERNOON AS SURFACE RIDGE AXIS SHIFTS EWD[FONT="]
[/FONT]AND EXIT REGION OF UPPER JET MOVES INTO THE HIGH PLAINS. THIS WILL[FONT="]
[/FONT]SUPPORT INCREASING LIFT ALONG/N OF WARM FRONT. RADAR IMAGERY ALREADY[FONT="]
[/FONT]SHOWS ISOLATED ELEVATED CELLS TRYING TO DEVELOP N OF THE FRONT OVER[FONT="]
[/FONT]CNTRL OK. OTHER STORMS WILL LIKELY DEVELOP FARTHER S CLOSER TO THE[FONT="]
[/FONT]SURFACE FRONT AS CAP WEAKENS THIS AFTERNOON. BACKED LOW LEVEL FLOW N[FONT="]
[/FONT]OF THE WARM FRONT UNDERNEATH MODERATE WLY MID LEVEL FLOW IS[FONT="]
[/FONT]SUPPORTING SUFFICIENT DEEP SHEAR FOR SUPERCELLS. LOW LEVEL FLOW IS[FONT="]
[/FONT]CURRENTLY RATHER WEAK..RESULTING IN RELATIVELY SMALL[FONT="]
[/FONT]HODOGRAPHS...AND THIS MAY INITIALLY SERVE AS LIMITING FACTOR FOR[FONT="]
[/FONT]TORNADOES. HOWEVER...STRENGTHENING LOW LEVEL JET LATER THIS[FONT="]
[/FONT]AFTERNOON SHOULD SUPPORT BIGGER HODOGRAPHS OVER THE SRN PLAINS WHICH[FONT="]
[/FONT]WOULD INCREASE THE THREAT OF ISOLATED TORNADOES.[FONT="]
[/FONT]
MD #6
MESOSCALE DISCUSSION 6[FONT="]
[/FONT]NWS STORM PREDICTION CENTER NORMAN OK[FONT="]
[/FONT]1248 PM CDT[FONT="]
[/FONT]AREAS AFFECTED...ERN WY...SWRN SD...NERN CO...AND THE NEB PANHANDLE[FONT="]
[/FONT]CONCERNING...SEVERE THUNDERSTORM POTENTIAL [FONT="]
[/FONT]VALID 1748Z - 2015Z[FONT="]
[/FONT]THUNDERSTORM DEVELOPMENT IS ANTICIPATED ACROSS THE CENTRAL HIGH[FONT="]
[/FONT]PLAINS REGION DURING THE NEXT 1-3 HOURS...PARTICULARLY ACROSS ERN[FONT="]
[/FONT]WY. THREAT OF SEVERE STORMS INCLUDING A FEW SUPERCELLS MAY REQUIRE[FONT="]
[/FONT]WW IN THE REGION LATER THIS AFTERNOON.[FONT="]
[/FONT]WATER VAPOR IMAGERY AT 1730Z SUGGESTS A REGION OF UPPER-LEVEL[FONT="]
[/FONT]DIVERGENCE SPREADING NEWD FROM THE CENTRAL ROCKIES TOWARD THE[FONT="]
[/FONT]DISCUSSION AREA. ASSOCIATED SURFACE PRESSURE FALLS ON THE ORDER OF[FONT="]
[/FONT]2-3 MB/2 HR CONTINUE ACROSS ERN CO...ERN WY...AND THE NEB PANHANDLE.[FONT="]
[/FONT]RAPID CLEARING OCCURRED LATE THIS MORNING ACROSS NERN CO...ERN[FONT="]
[/FONT]WY...THE NEB PANHANDLE SETTING THE STAGE FOR DESTABILIZATION AND[FONT="]
[/FONT]STEEPENING LOW-LEVEL LAPSE RATES ACROSS THE REGION THIS AFTERNOON.[FONT="]
[/FONT]VISIBLE IMAGERY ALSO SHOWS A CONSIDERABLE AMOUNT OF CUMULUS[FONT="]
[/FONT]DEVELOPMENT ACROSS THE MTNS OF CENTRAL WY.[FONT="]
[/FONT]AS FORCING FOR ASCENT EMERGES INTO THE CENTRAL HIGH PLAINS AREA THIS[FONT="]
[/FONT]AFTERNOON...IN CONJUNCTION WITH CONTINUED SURFACE[FONT="]
[/FONT]HEATING...ISOLATED/SCATTERED THUNDERSTORMS ARE EXPECTED FROM NERN WY[FONT="]
[/FONT]SWD INTO NERN CO. IF PRESSURE FALLS CAN REMAIN FOCUSED ALONG THE[FONT="]
[/FONT]FRONT RANGE...A SSELY BOUNDARY LAYER FLOW WILL CONTINUE TO ADVECT[FONT="]
[/FONT]MOISTURE /DEWPOINTS INTO THE LOW 50S/ INTO THE REGION ALLOWING FOR[FONT="]
[/FONT]100MB MLCAPE VALUES OF 1000-1500 J/KG AND AN ASSOCIATED THREAT OF[FONT="]
[/FONT]SEVERE STORMS. DEEP LAYER SHEAR /SFC-6KM/ AROUND 40KT SHOULD[FONT="]
[/FONT]INCREASE THIS AFTERNOON...AND SHOULD BE SUFFICIENT FOR ROTATING[FONT="]
[/FONT]STORMS. HAIL AND ISOLATED/LOCALIZED DAMAGING WINDS WILL BE THE[FONT="]
[/FONT]PRIMARY THREAT. HOWEVER...WHERE LOW-LEVEL FLOW REMAINS BACKED THIS[FONT="]
[/FONT]AFTERNOON...TORNADOES ARE ALSO POSSIBLE.[FONT="]
19z Update will be issued later this afternoon and 20z tonight...
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