Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS03 KWNS 040728
SWODY3
SPC AC 040727

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0227 AM CDT MON MAY 04 2015

VALID 061200Z - 071200Z

...THERE IS A SLGT RISK OF SVR TSTMS LATE WEDNESDAY AFTERNOON AND
EVENING ACROSS PARTS OF WESTERN/CENTRAL KANSAS...WESTERN OKLAHOMA
AND ADJACENT PORTIONS OF THE TEXAS PANHANDLE...AND PARTS OF SOUTH
CENTRAL NEBRASKA...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS SURROUNDING AREAS OF THE
CENTRAL AND SOUTHERN PLAINS...

...SUMMARY...
SCATTERED SEVERE STORMS APPEAR POSSIBLE LATE WEDNESDAY AFTERNOON AND
EVENING ACROSS PARTS OF THE CENTRAL AND SOUTHERN PLAINS.

...SYNOPSIS...
AMPLIFICATION OF THE MID-LATITUDE WESTERLIES ACROSS THE NORTH
CENTRAL AND NORTHEASTERN PACIFIC THROUGH THE WESTERN U.S. APPEARS
LIKELY TO CONTINUE DURING THIS FORECAST PERIOD.  WITHIN THIS
REGIME...THE ELONGATING SOUTHERN PORTION OF A SPLITTING SHORT WAVE
IMPULSE IS FORECAST TO CONTINUE DIGGING JUST INLAND OF THE PACIFIC
COAST.  DOWNSTREAM SHORT WAVE RIDGING WILL PROBABLY BUILD ACROSS THE
CENTRAL AND SOUTHERN ROCKIES...INTO ADJACENT PORTIONS OF THE CENTRAL
AND SOUTHERN PLAINS...IN THE WAKE OF A SHORT WAVE TROUGH EXPECTED TO
EMERGE FROM THE SOUTHERN INTERMOUNTAIN REGION ON TUESDAY.

THIS IMPULSE...WHICH IS EXPECTED TO REACH THE CENTRAL PLAINS BY 12Z
WEDNESDAY...MAY TEND TO SHIFT MORE NORTHWARD THAN EASTWARD THROUGH
THE MID MISSOURI VALLEY...WITH A MID-LEVEL HIGH CENTER INITIALLY
FAIRLY PROMINENT NEAR THE CENTRAL APPALACHIANS...TO THE NORTH OF A
DEVELOPING CYCLONE OFF THE SOUTH ATLANTIC COAST /ASSOCIATED WITH
UPPER TROUGHING IN THE SUBTROPICAL STREAM/.  AS THIS OCCURS...MODELS
INDICATE THAT LOW PRESSURE WILL CONTINUE TO DEEPEN WITHIN THE
NORTHERN PORTION OF LEE SURFACE TROUGHING SHIFTING OUT OF THE
NORTHERN AND CENTRAL HIGH PLAINS...TOWARD THE LOWER PLAINS.  A
GRADUAL FURTHER MOISTENING OF LOWER LEVELS AHEAD OF THE TROUGH AXIS
IS EXPECTED TO PROCEED ON MODERATE SOUTHERLY LOW-LEVEL FLOW.

...CENTRAL AND SOUTHERN PLAINS...
CONVECTIVE CLOUD COVER AND PRECIPITATION CURRENTLY APPEARS LIKELY TO
LIMIT BOUNDARY LAYER DESTABILIZATION AHEAD OF THE NORTH
NORTHEASTWARD PROGRESSING SHORT WAVE IMPULSE.  IN THE WAKE OF THIS
FEATURE...HOWEVER...IT DOES APPEAR THAT SURFACE HEATING... BOUNDARY
LAYER MOISTENING /SURFACE DEW POINTS IN THE LOWER TO MID 60S/...AND
AT LEAST MODEST STEEPENING OF MID-LEVEL LAPSE RATES WILL CONTRIBUTE
TO MODERATE MIXED LAYER CAPE ALONG A SHARPENING DRY LINE BY LATE
AFTERNOON.  DUE TO THE LACK OF WARMER ELEVATED MIXED LAYER
AIR...CAPPING SHOULD NOT BE PROHIBITIVE TO CONVECTIVE DEVELOPMENT.
SO...DESPITE WEAKER MID/UPPER FORCING FOR UPWARD VERTICAL
MOTION...THE INITIATION OF AT LEAST WIDELY SCATTERED DISCRETE STORMS
APPEARS PROBABLE.  AS 30-40+ KT CYCLONIC MID-LEVEL FLOW TAKES ON A
MORE WESTERLY COMPONENT IN THE IMMEDIATE WAKE OF THE UPPER
IMPULSE...CONTRIBUTING TO STRONG DEEP LAYER SHEAR...THERE APPEARS A
WINDOW OF OPPORTUNITY FOR A FEW SUPERCELLS CAPABLE OF PRODUCING
LARGE HAIL...LOCALLY DAMAGING WIND GUSTS...PERHAPS A COUPLE OF
TORNADOES.

IT REMAINS UNCLEAR HOW DEEP INTO THE EVENING THIS SEVERE THREAT WILL
PERSIST...AS MID-LEVELS TEND TO WARM...AND THE DRYLINE RETREATS
WESTWARD TOWARD THE HIGHER PLAINS.

..KERR.. 05/04/2015




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