Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS02 KWNS 280555
SWODY2
SPC AC 280554

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1254 AM CDT SAT MAR 28 2015

VALID 291200Z - 301200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
ISOLATED THUNDERSTORMS ARE POSSIBLE SUNDAY EVENING/NIGHT FROM THE
RED RIVER OF THE SOUTH TOWARDS THE SOUTHERN APPALACHIANS...WITH A
VERY LOW PROBABILITY FOR SEVERE HAIL.

...SYNOPSIS...
A SHORTWAVE TROUGH FROM MANITOBA TO THE UPPER MIDWEST AT 12Z/SUN
WILL AMPLIFY OVER THE GREAT LAKES WITH ASSOCIATED SURFACE CYCLONE
TRACKING E MAINLY OVER ONTARIO. ATTENDANT COLD FRONT WILL REACH THE
APPALACHIANS TO DEEP SOUTH...WITH TRAILING PORTION BECOMING
QUASI-STATIONARY OVER TX. A WEAK UPPER TROUGH SHOULD APPROACH BAJA
CA WITH A DOWNSTREAM UPPER JET OVERSPREADING THE SRN GREAT PLAINS.

...RED RIVER/ARKLATEX...
28/00Z RAOBS ALONG THE WRN/CNTRL GULF COAST SAMPLED A RATHER DRY AIR
MASS CHARACTERIZED BY MEAN MIXING RATIOS BETWEEN 3-5 G/KG. GOES PW
IMAGERY INDICATES THIS CONTINENTAL POLAR INTRUSION HAS OVERSPREAD
THE NRN 3/4 OF THE GULF BASIN. ALTHOUGH WEAK RETURN FLOW HAS
COMMENCED OVER THE FAR WRN GULF AND WILL BECOME INCREASINGLY
PERVASIVE AS WELL AS STRENGTHEN ON D2...THE 10-12 G/KG MEAN MIXING
RATIOS DEPICTED ACROSS GUIDANCE ALONG THE FRONT BY 30/00Z APPEARS A
BIT OVERDONE. WITH PERSISTENT WLYS BETWEEN 850-700 MB...A STOUT EML
/MOST REPRESENTATIVE IN WARM SECTOR NAM SOUNDINGS/ WILL LIKELY
PRECLUDE SURFACE-BASED TSTM DEVELOPMENT DURING THE DAY.

LOWER-LEVEL CONVERGENCE IS PROGGED TO STRENGTHEN SUN EVENING ALONG
THE FRONTAL ZONE AND THIS MIGHT BE SUFFICIENT TO YIELD NEGLIGIBLE
MUCIN FOR ELEVATED PARCELS N OF THE FRONT. GUIDANCE DIFFERS GREATLY
ON THE DEGREE OF NIGHTTIME CONVECTIVE QPF. IF STORMS WERE TO
DEVELOP...A MARGINAL RISK FOR SEVERE HAIL MAY OCCUR GIVEN VERY STEEP
MID-LEVEL LAPSE RATES AND MODEST EFFECTIVE SHEAR. UNCONDITIONAL
PROBABILITIES...WHILE NON-ZERO...DO NOT APPEAR TO BE AOA 5 PERCENT
THIS OUTLOOK.

...MID-SOUTH TO SRN APPALACHIANS...
CONFIDENCE IS HIGHER IN THE DEVELOPMENT OF AT LEAST ISOLATED TSTMS E
OF THE LOWER MS VALLEY SUN NIGHT. 700-MB HEIGHT FALLS SHOULD
OVERSPREAD THIS REGION ON THE PERIPHERAL INFLUENCE OF THE AMPLIFYING
GREAT LAKES TROUGH. IN CONJUNCTION WITH LOWER-LEVEL WAA ALONG THE
SURFACE FRONT WITHIN THE LEFT-EXIT REGION OF THE SRN-STREAM UPPER
JET...SETUP SHOULD FOSTER ELEVATED CONVECTION FORMING LATE EVENING
INTO THE OVERNIGHT. ALTHOUGH MID-LEVEL LAPSE RATES WILL INITIALLY BE
STEEP...WEAK BUOYANCY...MODEST CLOUD-BEARING SHEAR AND CLUSTER MODE
SHOULD LIMIT HAIL SIZE TO SUB-SEVERE.

..GRAMS.. 03/28/2015




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