Monday, May 17, 2010

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 170556
SWODY2
SPC AC 170555

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1255 AM CDT MON MAY 17 2010

VALID 181200Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN HIGH
PLAINS...

...SRN AND CNTRL HIGH PLAINS...
A NEGATIVELY-TILED UPPER-LEVEL TROUGH IS FORECAST TO MOVE ACROSS THE
FOUR CORNERS REGION AS A MID-LEVEL JET ROUNDS THE BASE OF THE
TROUGH. AHEAD OF THE SYSTEM...THE MODELS SHOW AN AXIS OF MODERATE
INSTABILITY EXTENDING NNWWD ACROSS WEST TX INTO SE CO WHERE
THUNDERSTORMS SHOULD INITIATE LATE TUESDAY AFTERNOON. FORECAST
SOUNDINGS AT 00Z ALONG THIS CORRIDOR LOOK QUITE IMPRESSIVE SHOWING
45 TO 55 KT OF DEEP LAYER SHEAR WITH MLCAPE OF 2500 TO 3000 J/KG.
THIS SHOULD EASILY SUPPORT SUPERCELL DEVELOPMENT AS STORMS INITIATE
AND INCREASE IN COVERAGE. THE STRONGEST VERTICAL SHEAR SHOULD EXIST
ACROSS THE TX PANHANDLE WHERE THE EXIT REGION OF THE MID-LEVEL JET
IS FORECAST TO APPROACH TUESDAY EVENING. THIS COMBINED WITH VERY
STEEP MID-LEVEL LAPSE RATES APPROACHING 8.0 C/KM MAY BE ENOUGH FOR
VERY LARGE HAIL WITH THE MORE DOMINANT SUPERCELLS. IN
ADDITION...LOW-LEVEL SHEAR WILL MARKEDLY INCREASE DURING THE EVENING
AS THE LOW-LEVEL JET STRENGTHENS MAKING TORNADOES POSSIBLE WITH THE
MORE PERSISTENT ROTATING STORMS. THE SEVERE THREAT MAY CONTINUE
DURING PART OF THE OVERNIGHT PERIOD AS LARGE-SCALE ASCENT INCREASES
AND LOW-LEVEL FLOW STRENGTHENS AHEAD OF THE APPROACHING UPPER-LEVEL
TROUGH. THE GFS AND NAM ARE IN RELATIVELY GOOD
AGREEMENT...DEVELOPING SCATTERED THUNDERSTORMS TUESDAY EVENING AND
OVERNIGHT ACROSS THE TX AND OK PANHANDLES SUGGESTING CONFIDENCE IS
GREATEST IN THIS AREA CONCERNING THE SLIGHT RISK.

..BROYLES.. 05/17/2010

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