Tornado threat shifts east today

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0736 AM CDT THU APR 22 2010

VALID 221300Z - 231200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CENTRAL AND
SOUTHERN PLAINS...

...SYNOPSIS...
SPLIT FLOW PATTERN WILL CONTINUE THROUGH THIS FORECAST PERIOD AS A
LARGE UPPER LOW OVER SRN NV GRADUALLY REDEVELOPS EWD ACROSS THE SRN
ROCKIES. THIS WILL OCCUR AS A SERIES OF SHORT WAVES/VORTICITY LOBES
ROTATE THROUGH THE SRN/ERN PERIPHERY OF THE CIRCULATION. AN INITIAL
PERTURBATION EVIDENT IN WATER VAPOR IMAGERY OVER EXTREME ERN AZ IS
LIFTING NEWD TOWARD THE CENTRAL ROCKIES AND HIGH PLAINS...WHILE A
SECOND FEATURE DIGGING SEWD ALONG THE SRN CA COAST IS FORECAST TO
TURN EWD ACROSS THE SRN AZ/NM BORDER TODAY AND CONTINUE INTO THE
CENTRAL HIGH PLAINS TONIGHT.

AT THE SURFACE...A SERIES OF LOW CENTERS ARE LOCATED OVER THE
CENTRAL/SRN ROCKIES FROM WY SWD INTO NM. A DRY LINE IS ALONG THE
FRONT RANGE OF CO SWD ACROSS ERN NM INTO SWRN TX...IN ADVANCE OF A
N-S COLD FRONT THAT IS MOVING EWD OVER THE CENTRAL PARTS OF CO AND
NM. A WARM FRONT EXTENDS FROM A LOW OVER SERN CO ESEWD NEAR THE
KS/OK BORDER INTO NWRN AR AND IS EXPECTED TO MOVE SLOWLY NWD THROUGH
TONIGHT. THE MULTIPLE LOW PRESSURE CENTERS ARE EXPECTED TO
CONSOLIDATE INTO A SINGLE LOW OVER ERN CO TONIGHT IN RESPONSE TO
DYNAMIC AND OROGRAPHIC FORCING ASSOCIATED WITH THE SECOND SHORT WAVE
TROUGH. AS THE LOW DEVELOPS...THE DRY LINE IS LIKELY TO MIX EWD THIS
AFTERNOON BEFORE BECOMING QUASI-STATIONARY ACROSS SWRN KS/TX
PANHANDLE/WEST TX. BY THIS EVENING THE COLD FRONT IS FORECAST TO
ACCELERATE EWD AND OVERTAKE THE DRY LINE...REACHING AN ARCING LINE
FROM NORTHWEST INTO SOUTH CENTRAL KS/CENTRAL OK/AND WRN PARTS OF
NORTH CENTRAL AND SOUTH CENTRAL TX BY 23/12Z.

...NERN CO/KS AREA...
SEVERAL BANDS OF ELEVATED THUNDERSTORMS ARE MOVING EWD/NEWD ACROSS
THE REGION THIS MORNING IN RESPONSE TO LOW LEVEL WARM ADVECTION AND
CONVERGENCE NORTH OF THE SURFACE WARM FRONT IN ASSOCIATION WITH A
BROAD SSWLY LOW LEVEL JET OVER THE SRN PLAINS. A LAYER OF STEEPER
MID LEVEL LAPSE RATES HAS ENHANCED HAIL POTENTIAL IN STRONGER CELLS
DURING THE EARLY MORNING HOURS...BUT SLOW WEAKENING OF THE LOW LEVEL
JET SHOULD LIMIT THE SEVERE HAIL THREAT THIS MORNING.

ADDITIONAL STORMS ARE LIKELY TO DEVELOP AND INTENSIFY DURING THE
EARLY/MID AFTERNOON FROM NERN CO INTO PARTS OF KS AS DYNAMIC FORCING
ASSOCIATED WITH THE LEAD SHORT WAVE TROUGH MOVES TOWARD THE HIGH
PLAINS AND COOLING ALOFT OVERSPREADS THE AREA FROM THE WEST.
SURFACE DEW POINTS AROUND 60F ARE EXPECTED TO SPREAD NWD INTO PARTS
OF KS...WITH 50F DEW POINTS MOVING INTO NERN CO AS MOIST SELY LOW
LEVEL FLOW PERSISTS. WIDESPREAD CLOUD COVER AND PRECIPITATION IS
LIKELY TO INHIBIT DIURNAL INSOLATION TODAY...HOWEVER LOCALIZED
REGIONS OF ENHANCED HEATING WITHIN CLOUD BREAKS WILL CONTRIBUTE TO
ADDITIONAL DESTABILIZATION.

EFFECTIVE BULK SHEAR OF 35-45 KT WILL BE SUFFICIENT TO SUPPORT STORM
ROTATION...WITH POTENTIAL FOR MORE INTENSE CELLS TO PRODUCE LARGE
HAIL AND POSSIBLY A FEW TORNADOES...ESPECIALLY FROM NERN CO INTO WRN
KS WHERE STEEPER LAPSE RATES WILL BE PRESENT.

...PARTS OF WRN AND N CENTRAL TX INTO WRN/CENTRAL OK...
CONVECTION OVER THE TX PANHANDLE AREA HAS BEEN SLOWLY WEAKENING AND
THIS TREND IS LIKELY TO CONTINUE THROUGH THE MORNING AS IT MOVES
NEWD INTO WRN OK. IN THE WAKE OF THESE STORMS...SOME DECREASE IN
CLOUD COVER IS EXPECTED WHICH WILL PERMIT REGIONS OF AFTERNOON
HEATING TO DEVELOP...WITH SURFACE TEMPERATURES WARMING INTO THE
75-80F RANGE. WITH SURFACE DEW POINTS OF 60-65F EAST OF THE DRY
LINE...THE ENVIRONMENT WILL BECOME MODERATELY UNSTABLE WITH MLCAPE
OF 1500-2000 J/KG.

STORMS ARE EXPECTED TO REDEVELOP LATE THIS AFTERNOON AND EVENING
ALONG/EAST OF THE DRY LINE...WITH HIGH RESOLUTION WRF GUIDANCE
INDICATING SEVERAL BANDS OF SCATTERED STRONG/SEVERE STORMS FORMING.
THE INITIAL STORMS ARE EXPECTED TO DEVELOP OVER CENTRAL/ERN TX
PANHANDLE BEFORE THEY MOVE INTO WRN OK...FOLLOWED BY A MORE
EXTENSIVE BAND OF STORMS FROM THE ERN TX PANHANDLE SWD INTO THE
SOUTH PLAINS AS THE COLD FRONT SURGES EWD TONIGHT. STRONG DEEP
LAYER SHEAR WILL CONTRIBUTE TO SUPERCELL GENERATION...ESPECIALLY
WITH MORE DISCRETE CELLS THAT FORM INITIALLY...AND THE COMBINATION
OF STEEP LAPSE RATES AND FAVORABLE LOW LEVEL SHEAR/SRH WILL RESULT
IN A FEW STRONGER SUPERCELLS CAPABLE OF PRODUCING VERY LARGE HAIL
AND TORNADOES.

A BETTER DEFINED LINEAR MCS IS FORECAST TO DEVELOP ALONG THE
ACCELERATING COLD FRONT DURING THE EVENING...FIRST OVER THE ERN TX
PANHANDLE WITH GRADUAL DEVELOPMENT SWD INTO THE SOUTH PLAINS. WIND
PROFILES SUGGEST THE LINE MAY CONTAIN EMBEDDED BOW/LEWP STRUCTURES
WITH PERHAPS A TRANSITION TO AN ENHANCED DAMAGING WIND THREAT
TONIGHT FROM PARTS OF WRN/NORTH CENTRAL TX INTO WRN/CENTRAL OK.
OWING TO ANTICIPATED LOW LEVEL COOLING AND STABILIZATION COUPLED
WITH UNCERTAINTY IN THE DETAILS OF THE CONVECTIVE MODE...WE HAVE
OPTED TO NOT INCLUDE HIGHER WIND PROBABILITIES AT THIS TIME BUT THIS
POSSIBILITY WILL BE MONITORED IN LATER OUTLOOKS.