SPC AC 271725
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1225 PM CDT MON APR 27 2009
VALID 281200Z - 291200Z
...THERE IS A SLGT RISK OF SVR TSTMS SRN HIGH PLAINS AND NRN TX...
...SYNOPSIS...
SHORTWAVE TROUGH...CURRENTLY LOCATED OVER THE CENTRAL PORTIONS OF
THE COUNTRY...WILL EJECT NEWD AND DEAMPLIFY AS IT MERGES WITH A
STRONGER TROUGH MOVING EWD ACROSS SERN CANADA. THESE SYSTEMS WILL
PUSH A COLD FRONT EWD THROUGH THE NERN QUARTER OF THE COUNTRY ON
TUE...WHILE THE WRN PORTION OF THE FRONT STALLS ACROSS THE MIDDLE
MS/SRN PLAINS REGION. ANOTHER TROUGH DIGGING SWD THROUGH ORE/NRN CA
IS FORECAST TO EVOLVE INTO A BROAD UPPER LOW IN THE PACIFIC NW. THIS
WILL RESULT IN BROAD CYCLONIC FLOW WITH EMBEDDED SHORTWAVE TROUGHS
EXTENDING FROM THE SWRN STATES NEWD INTO CENTRAL/SRN PLAINS.
...SRN HIGH PLAINS AND NRN TX...
FRONT IS EXPECTED TO STRETCH ACROSS NRN TX WWD IN THE SRN TX
PANHANDLE DURING THE MORNING. SCATTERED CONVECTION MAY BE OCCURRING
ALONG AND NORTH OF THE FRONT...ESPECIALLY ACROSS THE TX PANHANDLE
...WHERE STRONGER FORCING IS EXPECTED DUE TO STRENGTHENING LOW LEVEL
JET/ISENTROPIC LIFT. COMBINATION OF STEEP MID LEVEL LAPSE RATES AND
MOISTENING ADVECTION ABOVE THE BOUNDARY LAYER INDICATE A MARGINAL
THREAT FOR SEVERE HAIL WITH ELEVATED THUNDERSTORMS DURING THE
MORNING.
HOWEVER...THE COMBINATION OF DIURNAL HEATING AND DEWPOINTS IN THE
50S IN NM AND 60S IN TX SHOULD RESULT IN MODERATE INSTABILITY
...WITH MLCAPES FROM 1000 TO 2000 J/KG ACROSS THE SLIGHT RISK AREA.
A SHORTWAVE TROUGH IS PROGGED TO MOVE INTO THE WRN TX BY
AFTERNOON...AND STORMS ARE LIKELY TO DEVELOP ALONG NWD DRIFTING E-W
ORIENTED FRONT...REMNANT BOUNDARIES FROM MORNING CONNECTION AND IN
MOISTENING UPSLOPE FLOW REGIME ACROSS ERN NM. VEERING WINDS IN THE
LOWER 3KM COMBINED WITH MODERATE 40 KT WSWLY MID LEVEL WINDS WILL
CONTRIBUTE TO EFFECTIVE SHEAR NEAR 40 KT AND SUPERCELLS DURING THE
AFTERNOON/EVENING HOURS. ALTHOUGH THERMODYNAMIC PROFILES LOOK MOST
FAVORABLE FOR LARGE HAIL...STRONG TURNING IN THE LOWER 1-2 KM AND A
RELATIVELY MOIST BOUNDARY LAYER FAVORS SOME TORNADO DEVELOPMENT IN
ERN NM AND THE TEXAS PANHANDLE.
OVERNIGHT...ELEVATED STORMS ARE EXPECTED TO DEVELOP NWD IN ZONE OF
STRONG WARM ADVECTION...THOUGH WEAK INSTABILITY SHOULD LIMIT SEVERE
POTENTIAL WITH THESE STORMS.
...MID MS VALLEY NEWD INTO THE NEW ENGLAND...
THOUGH CONVECTION IS EXPECTED TO BE ONGOING ACROSS PORTIONS OF THE
MID MS/TN AND INTO THE OH VALLEYS IN THE MORNING...WEAK LAPSE RATES
SHOULD RESULT IN A LOW THREAT FOR SEVERE. IN THE NERN STATES
...LIMITED INSTABILITY WILL EXIST AHEAD OF ADVANCING COLD FRONT.
THIS INSTABILITY ALONG WITH AFTERNOON HEATING AND CONVERGENCE MAY
SUPPORT SCATTERED STORMS ALONG THE FRONT. DESPITE WEAK INSTABILITY
...MODERATE/STRONG UNIDIRECTIONAL WSWLY WINDS INDICATE A THREAT OF
ISOLATED WIND GUSTS BETWEEN 18Z-01Z.
..IMY.. 04/27/2009
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z
|
