Friday, March 20, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 210059
SWODY1
SPC AC 210056

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0756 PM CDT FRI MAR 20 2009

VALID 210100Z - 211200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
SYNOPTIC SCALE PATTERN IS CHARACTERIZED BY SLOWLY PROGRESSIVE
TROUGHING OVER E COAST...AND RIDGING FROM NRN MEX ALONG CONUS HIGH
PLAINS TO SASK. WEAK/EMBEDDED SHORTWAVE TROUGHS ARE EVIDENT IN
MOISTURE CHANNEL IMAGERY AND AVAILABLE RAOB DATA OVER CO...AND IN
SRN STREAM...OVER PORTIONS SONORA/AZ. CENTRAL ROCKIES PERTURBATION
IS WEAK...BUT MAY BE REINFORCED CONVECTIVELY OVERNIGHT ACROSS
PORTIONS KS. SRN STREAM TROUGH SHOULD CONTINUE MOVING
ENEWD...CROSSING PORTIONS NM AND FAR W TX.

AT SFC...PRIMARY LEE-SIDE LOW IS ANALYZED OVER SERN CO VICINITY
TAD...AND SHOULD REMAIN WEAK/QUASISTATIONARY THROUGH REMAINDER
PERIOD. DIFFUSE WARM FRONT IS ANALYZED FROM NE TX NWWD ACROSS
CENTRAL OK AND NWRN KS...THEN SWWD ACROSS E-CENTRAL CO INTO LOW.
SLIGHT NWD DRIFT IS POSSIBLE OVERNIGHT. MOISTURE RETURN IS TOO
IMMATURE YET...AND WRN GRADIENT TOO DIFFUSE/IRREGULAR...FOR DEFINING
DRYLINE ATTM.

...CENTRAL PLAINS...
ISOLATED...TSTM DEVELOPMENT OVER OK PANHANDLE DURING PAST HOUR
APPEARS TO BE SFC BASED...USING MODIFICATION OF AMA/DDC RAOBS AND
RUC SOUNDINGS...AND APPEARS TO BE WEAKENING WITH LOSS OF DIABATIC
HEATING. PRIMARY REGIONAL CONVECTIVE MODE THROUGH REMAINDER PERIOD
SHOULD BE MORE CLUSTERED AND ELEVATED. EXPECT SCATTERED TSTMS TO
DEVELOP OVERNIGHT ACROSS PORTIONS CENTRAL/SRN KS...PERHAPS IN
MULTIPLE NODES THAT EVENTUALLY MAY LINK INTO WEAKLY ORGANIZED MCS.
RESULTANT CONVECTION THEN SHOULD MOVE EWD OR ESEWD ACROSS SRN
KS...AND PERHAPS PORTIONS NERN OK AND SWRN MO...BEFORE 12Z. MRGL
SVR HAIL MAY OCCUR FROM MOST INTENSE TSTMS IN THIS
ACTIVITY...ESPECIALLY ACROSS SRN KS.

BROAD LOW LEVEL WAA REGIME FCST TO CONTINUE ACROSS SRN/CENTRAL
PLAINS THROUGH REMAINDER PERIOD. MOISTURE ADVECTION AND TRANSPORT
EMBEDDED WITHIN THIS REGIME -- AND ABOVE DIABATICALLY STABILIZED
BOUNDARY LAYER -- WILL GRADUALLY BOOST RH OVERNIGHT INVOF 35-45 KT
LLJ. BY 06Z...AXIS OF LLJ IS EXPECTED TO EXTEND FROM COAHUILA NWD
ACROSS TX SOUTH-PLAINS REGION THEN NEWD OVER ERN PANHANDLE TO
S-CENTRAL KS. LLJ CORE THEN SHOULD VEER SLIGHTLY AND SHIFT EWD
ACROSS WRN OK AND S-CENTRAL/SERN KS OVERNIGHT. MAINLY NW OF LLJ
AXIS...PARCEL RH WILL INCREASE TO NEAR SATURATION IN LAYER THAT WILL
BE SHALLOW IN VERTICAL EXTENT BUT BROAD HORIZONTALLY...BENEATH STEEP
MID-UPPER LEVEL LAPSE RATES. PARCELS WILL BE LIFTED ISENTROPICALLY
TO LFC...ACCESSING ELEVATED MUCAPE COMMONLY IN 500-1000 J/KG RANGE.
EFFECTIVE SHEAR MAGNITUDES ARE FCST TO BE GREATER OVER
S-CENTRAL/SWRN KS THAN FARTHER E...WITH DEEPEST BUOYANT PROFILES
YIELDING VALUES OF 40-45 KT.

..EDWARDS.. 03/21/2009

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