Heavy Snow Warning 2, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
302 PM CST THU DEC 27 2007

.DISCUSSION...
THE NEXT STORM SYSTEM IN LINE OVER NM/CO WILL MOVE ENE TOWARD
NORTHWEST OKLAHOMA AND KANSAS THIS EVENING WITH A 95-110 KT 500 MB
JET APPROACHING OKLAHOMA. PRECIPITATION WILL INCREASE THIS
EVENING... ESPECIALLY IN NORTHERN OKLAHOMA. MID LEVEL TEMPERATURES
ARE ALSO QUITE COLD WITH -35 TEMPERATURE OBSERVED AT 500 MB THIS
MORNING OVER ARIZONA... AND TEMPERATURES NEAR -30 OR BELOW
EXPECTED OVER NORTHERN OKLAHOMA. AT LOWER LEVELS... SOME
FRONTOGENESIS IS PROGGED AHEAD OF LOW LEVEL CYCLONE AND ALTHOUGH
IS NOT PROGGED TO BE TOO STRONG OVER THE AREA... STILL MAY BE
ENOUGH TO AID IN ENHANCED LIFT IN NORTHERN OKLAHOMA. WITH SLIGHT
FRONTOGENETIC SIGNAL AND WITH 12Z MODEL QPFS SQUEEZING OUT 0.3 TO
0.6 INCH OF LIQUID... WILL GO AHEAD AND UPGRADE NORTHERN OKLAHOMA
TO A HEAVY SNOW WARNING WITH EXPECTED ACCUMULATIONS AVERAGING 3 TO
5 INCHES WITH SOME HIGHER TOTALS POSSIBLE. FARTHER SOUTH... WILL
MAINTAIN CURRENT ADVISORY AREA WHERE WE ARE NOT UPGRADING.

ALSO OF SOME CONCERN FOR TONIGHT IS THE TIMING OF THE MID LEVEL
DRY SLOT RELATIVE TO THE END OF THE LOW LEVEL LIFT NEAR THE
SURFACE CYCLONE. THE MODEL TIME-HEIGHT CROSS-SECTIONS SHOW
SIGNIFICANT DRYING IN THE ELEVATIONS WHERE TEMPERATURES SUPPORT
ICE CRYSTAL GROWTH. IF THE MID-LEVEL DRYING OCCURS BEFORE THE LOW-
LEVEL LIFT AND ASSOCIATED PRECIP ENDS... THERE WILL BE A WINDOW OF
TIME WHERE FREEZING RAIN OR FREEZING DRIZZLE WILL BE POSSIBLE. LOW
LEVEL TEMPERATURE PROFILE WILL ALSO PLAY A ROLE IN THIS
POSSIBILITY WITH LOW-LEVEL WARM ADVECTION AHEAD OF THE SURFACE
CYCLONE. AM NOT SURE HOW LIKELY THE FZRA SCENARIO IS... BUT THE
MODEL CROSS-SECTIONS SHOW ENOUGH OF A CHANCE OF THIS OCCURRING IN
THE SOUTHWEST AND PERHAPS CENTRAL SECTIONS THAT WILL INCLUDE THE
MENTION OF SLIGHT CHANCE OF FREEZING RAIN IN THIS PACKAGE.

THIS STORM SYSTEM MOVES QUICKLY AWAY FROM THE AREA AND
PRECIPITATION WILL LIKELY HAVE MOVED OUT OF THE CWA BY 12Z.
ANOTHER SHORTWAVE MOVES THROUGH THE AREA EARLY SUNDAY AND WILL
MAINTAIN THE SLIGHT CHANCE POPS EAST OVERNIGHT SATURDAY NIGHT...
ALTHOUGH MOISTURE AVAILABILITY IS IN QUESTION.

AFTER SUNDAYS SYSTEM WE WILL HAVE ONE MORE WAVE ON MONDAY/MONDAY
NIGHT AND THEN IT APPEARS THAT THE CAVALCADE OF STORM SYSTEMS MAY
FINALLY BE OVER AS RIDGING AMPLIFIES IN THE WESTERN UNITED STATES.
THE STRONG NORTHERLY MID-LEVEL FLOW ON THE EAST SIDE OF THIS
AMPLIFICATION WILL BE CLOSE ENOUGH THAT WE WILL HAVE TO WATCH FOR
SOME RELATIVELY COLD AIR SWEEPING DOWN THE PLAINS... BUT PRECIP
CHANCES WILL BE LOW.

&&

.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK  29  40  22  45 /  50  10   0  10
HOBART OK         27  42  20  47 /  40   0   0  10
WICHITA FALLS TX  30  47  24  54 /  20   0   0  10
GAGE OK           21  35  14  39 /  90   0   0  10
PONCA CITY OK     27  35  18  39 /  90  10   0  10
DURANT OK         35  50  28  53 /  50  10   0  10

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...SNOW ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST FRIDAY FOR
     OKZ013>020.

     HEAVY SNOW WARNING FROM 6 PM THIS EVENING TO 6 AM CST FRIDAY FOR
     OKZ004>012.

TX...NONE.
&&

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