SWODY1
SPC AC 140100
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0700 PM CST TUE DEC 13 2011
VALID 140100Z - 141200Z
...NO SVR TSTM AREAS FORECAST...
...SWRN STATES TO CENTRAL/SRN PLAINS AND LOWER MO VALLEY...
SHORTWAVE TROUGH CENTERED OVER SRN AZ/NWRN MEXICO EARLY THIS EVENING
AND THE PARENT SWRN STATES LONGWAVE TROUGH WILL TRACK ENEWD TOWARD
THE SRN/CENTRAL HIGH PLAINS THIS FORECAST PERIOD.
CONVECTION/ELEVATED TSTMS WILL CONTINUE TO BE POSSIBLE ACROSS AZ/NM
TONIGHT AS COLD MIDLEVEL TEMPERATURES/STEEP LAPSE RATES AND ASCENT
SPREAD ENEWD ATTENDANT TO THE PROGRESSIVE SRN AZ SHORTWAVE TROUGH.
GIVEN THIS TSTM THREAT AND AN INCREASE IN TSTM POTENTIAL DOWNSTREAM
E OF THE ROCKIES...NO CHANGES ARE NEEDED TO THE 20Z GENERAL TSTM
AREA.
WATER VAPOR IMAGERY AND OBJECTIVE ANALYSES INDICATED SEVERAL
IMPULSES HAVE EJECTED NEWD ACROSS ERN NM/W TX INTO THE CENTRAL
PLAINS WITHIN THE ERN PERIPHERY OF THE SWRN STATES TROUGH AND AS
STRONGER SWLY FLOW ALOFT EMERGES ACROSS OK/KS/NEB TO THE LOWER MO
VALLEY. A FEW LIGHTNING STRIKES HAVE ALREADY BEEN NOTED OVER
SWRN/CENTRAL OK AND SRN KS. HEIGHT FALLS SPREADING TO THE CENTRAL
PLAINS WILL SUPPORT A MARKED STRENGTHENING OF THE SLY LLJ THIS
EVENING/TONIGHT FROM CENTRAL TX TO CENTRAL KS. 00Z SOUNDINGS SHOWED
STEEP MIDLEVEL LAPSE RATES WERE ALREADY IN PLACE FROM W TX TO THE
CENTRAL PLAINS...WHILE FURTHER LOW LEVEL MOISTENING/WARM AIR
ADVECTION WILL DESTABILIZE THE ENVIRONMENT SUFFICIENTLY FOR
ADDITIONAL ELEVATED TSTMS E OF THE ROCKIES. HOWEVER...FORECAST
SOUNDINGS CONTINUE TO SUGGEST THIS LOW LEVEL DESTABILIZATION WILL
NOT PROVE EFFICIENT ENOUGH FOR MUCH OF THE OVERNIGHT FOR SURFACE
BASED STORMS...GIVEN THE DEGREE OF STABILITY IN THE PREEXISTING
BOUNDARY LAYER PER THE 00Z SOUNDINGS.
STRONG BULK SHEAR AND ELEVATED MUCAPE 400-800 J/KG SUGGEST A FEW OF
THE STRONGER STORMS FROM NWRN TX THROUGH WRN OK SRN AND MAYBE ERN KS
WILL HAVE THE POTENTIAL TO PRODUCE HAIL LATE TONIGHT AS STRONGER
ASCENT/HEIGHT FALLS SPREAD INTO THIS REGION. HOWEVER FORECAST
SOUNDING CONTINUE TO INDICATE THAT THIS HAIL SHOULD REMAIN LESS THAN
1 INCH IN DIAMETER.
AN AREA OF CONCERN CONTINUES TO EXIST OVER NWRN TX/FAR SWRN OK
/INVOF OF SPS/ WHERE MODELS/FORECAST SOUNDINGS INDICATED A
COMPARATIVELY WARMER/MOIST BOUNDARY LAYER WILL ADVECT INTO THIS
REGION BETWEEN 14/09-12Z. IF THIS OCCURS...THEN STORMS WOULD HAVE A
GREATER LIKELIHOOD TO BECOME SURFACE BASED AND THUS REALIZE STRONGER
LOW LEVEL SHEAR IN ADDITION TO THE STRONG BULK SHEAR FOR A COUPLE OF
ORGANIZED STORMS/SUPERCELLS WITH A THREAT FOR SEVERE HAIL...DAMAGING
WINDS AND EVEN AN ISOLATED TORNADO. GIVEN THE SHORT DURATION OF
THIS THREAT LATE IN THE FORECAST PERIOD AND STILL SOME UNCERTAINTY
IN THE POTENTIAL FOR SURFACE BASED STORMS...THIS OUTLOOK WILL
INTRODUCE LOW SEVERE PROBABILITIES BUT ABSTAIN FROM INTRODUCING A
CATEGORICAL RISK.
..PETERS.. 12/14/2011
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