Severe Thunderstorm Warning 139, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
616 PM CDT MON APR 22 2013

.DISCUSSION...
00Z AVIATION DISCUSSION FOLLOWS....

&&

.AVIATION...
A STRONG COLD FRONT IN KS WILL SWEEP SE THIS
EVENING/OVERNIGHT...BRINGING A VARIETY OF ADVERSE WEATHER. SCT
+TSRA...A FEW POSSIBLY SEVERE...WILL OCCUR AHEAD OF THE
FRONT...MAINLY ACROSS THE N 1/3 OF OK...THIS EVENING. LOW CEILINGS
AND -RA WILL FOLLOW BEHIND THE FRONT...AND SOME PL WILL BE
POSSIBLE IN NW OK LATE TONIGHT AND EARLY TUESDAY. SOME BRIEF FZDZ
OR FZRA WILL ALSO BE A POSSIBILITY IN THESE AREAS...BUT PL WILL
LIKELY DOMINATE AS THE LOW-LEVEL...BUT ABOVE GROUND...TEMPERATURE
FALLS RAPIDLY BELOW FREEZING. LITTLE OR NO IMPROVEMENT IS
EXPECTED THROUGH TOMORROW AFTERNOON...AS IFR OR LOW MVFR
CONDITIONS ARE EXPECTED TO PERSIST IN THE COLD AND MOIST AIRMASS.

&&

.PREV DISCUSSION... /ISSUED 420 PM CDT MON APR 22 2013/

DISCUSSION...
SURFACE ANALYSIS THIS AFTERNOON PLACES THE COLD FRONT STILL WELL
NORTH OF THE FORECAST AREA...FROM NEAR SWRN IA THROUGH NWRN
KS...NEAR THE CENTER OF THE SFC LOW...ERN CO/WRN KS. A FAIRLY STOUT
500MB SHRTWV TROUGH WELL DEFINED ON WV IMAGERY WILL CONTINUE TO
SWING SOUTHWARD ACROSS THE NORTHERN ROCKIES THIS AFTERNOON/EVENING.
IN RESPONSE...THE COLD FRONT WILL SURGE SOUTHWARD ACROSS OKLAHOMA
THIS EVENING. TIMING OF THE FRONT REACHING NWRN OK STILL APPEARS TO
BE AROUND/NEAR 23/00Z.

AS FOR STORM DEVELOPMENT...AS HAS BEEN DISCUSSED WITH PREVIOUS
FORECASTS...INSTABILITY AHEAD OF THE FRONT WILL REMAIN WEAK TO
MODEST. THIS IS DUE TO LIMITED MOISTURE RETURN/FLOW ACROSS THE
REGION. AT 1830Z...UP STREAM DEWPOINTS FROM THE TX GULF COAST WERE
ONLY IN THE UPPER 50S...WITH UPPER 40S TO LOWER 50S ACROSS THE OK/KS
BORDER. HOWEVER...DYNAMICALLY...WIND FIELDS REMAIN FAVORABLE FOR
ORGANIZED CONVECTION...ALONG WITH A FEW SEVERE STORMS ACROSS NWRN
AND NRN/CTRL OK. PRIMARY CONCERNS WILL BE LARGE HAIL AND DAMAGING
WINDS. LARGE HAIL WILL ESPECIALLY BE A CONCERN IF THE FRONT
CRASHES HARD TO THE SOUTH...WITH STORMS MIGRATING BEHIND THE
LEADING EDGE/INTO THE COLD SECTOR.

THE SECONDARY CONCERN WITH THIS SYSTEM WILL BE WINTRY PRECIP AND
VERY COLD TEMPERATURES SPREADING FROM THE NW TO THE SE ACROSS THE
REGION. FZRA/SLEET/SN WILL BE POSSIBLE OVERNIGHT THROUGH DAY BREAK
ACROSS NWRN OK. AT THE MOMENT...NOT EXPECTING ANY SIGNIFICANT
IMPACTS AS MOISTURE AND COVERAGE REMAIN LIMITED. HOWEVER...SOME
SECONDARY ROADS MAY BECOME SLICK.

WITH SUCH UNSEASONABLE COLD TEMPERATURES...THIS WILL BE ANOTHER
SIGNIFICANT EARLY SPRING FREEZE EVENT...PERHAPS RECORD SETTING. WILL
ISSUE A FREEZE WARNING FROM 23/08Z-23/15Z FOR COUNTIES ACROSS NWRN
OK AS MORNING LOWS WILL BE IN THE UPPER 20S/LOWER 30S. THIS AIR MASS
WILL CONTINUE TO SETTLE OVER THE REGION THROUGH TUESDAY...WITH
FORECAST HIGHS ONLY IN THE LOWER 40S FROM CENTRAL OK TO NRN OK...THE
RECORD LOW HIGH FOR TUESDAY AT OKC WILL LIKELY BE IN JEOPARDY.

RECORD LOWS WILL BE IN JEOPARDY WEDNESDAY MORNING AS FREEZING TEMPS
SPREAD AS FAR SOUTH AS THE I-40/I-44 CORRIDOR...INCLUDING THE OKC
METRO.

FOR THE REMAINDER OF THE WEEK...SHOWER AND THUNDERSTORM CHANCES WILL
RETURN LATE IN THE WEEK...WITH A WARMING TREND THROUGH THE WEEKEND.

JTK

&&

.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK  37  41  31  58 /  70  40  10  10
HOBART OK         35  44  29  58 /  40  20  10  10
WICHITA FALLS TX  41  50  33  60 /  20  30  10  10
GAGE OK           28  40  25  59 /  70  30  10  10
PONCA CITY OK     35  41  29  59 / 100  50  10  10
DURANT OK         56  61  35  61 /  20  40  40  10

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...FREEZE WARNING FROM 3 AM TO 10 AM CDT TUESDAY FOR OKZ004>007-
     009>012-014>017-021-022.

TX...NONE.
&&

25/23/23

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