FXUS63 KOAX 262123
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
323 PM CST SAT DEC 26 2009
.SHORT TERM...TONIGHT THROUGH TUESDAY
UPPER LOW PULLING AWAY SLOWLY TO THE NORTHEAST WILL DICTATE WEATHER
FOR NEXT DAY OR SO. 20Z WATER VAPOR IMAGERY INDICATES UPPER LOW IS
CENTERED IN WI...THOUGH TROUGH COVERS THE CONUS FROM WA/OR THROUGH
NM/TX AND TOWARD THE ERN GT LAKES. SECONDARY VORT LOBE/1.5 PVU
PRESSURE MAX WAS LOCATED OVER OR...AND IS PROGGED TO PINCH OFF FROM
MAIN UPPER LOW...BECOMING WRAPPED INTO A DEVELOPING LOW OFF THE PAC
NW COAST. SURFACE LOW AT 20Z WAS CENTERED IN E CNTRL IA...WITH
PRESSURE RISES OVER THE MO RIVER VALLEY AND PRESSURE FALLS IN THE GT
LAKES INDICATING EWD PROGRESS.
MAIN FORECAST CONCERN IS IN DURATION OF LINGERING SNOW SHOWERS.
ANOTHER SHORTWAVE/VORT LOBE IS PROGGED TO ROTATE AROUND THE BACK
EDGE OF THE MAIN UPPER LOW TNGT...BRINGING ANOTHER ROUND OF SNOW
SHOWERS TO THE CWA /PARTICULARLY THE NERN SIDE/. LATEST 1.5PVU
PRESSURE INDICATES LOBE IS CURRENTLY SWINGING FROM MI INTO WI...AND
MODELS INDICATE IT WILL CONTINUE TO SWING AROUND THROUGH
MN/IA...WITH YET ANOTHER WEAK WAVE MOVING THROUGH THE MO VALLEY ON
SUNDAY AFTERNOON. KEPT CHC TO LIKELY POPS TNGT...AND SCHC TMRW
MRNING...BEFORE TAPERING BACK TO FLURRIES. LIFT IS IN THE DENDRITIC
GROWTH ZONE FROM ABOUT 900-700MB WHILE THE WAVE ROTATES
THROUGH...BUT LIFT IS ALSO RELATIVELY WEAK AND STATIC STABILITY
INCREASES WITH TIME AS THE UPPER LOW PULLS AWAY. THUS...ADDITIONAL
ACCUMULATIONS SHOULD REMAIN UNDER AN INCH IN MOST PLACES.
KEPT DIURNAL SWING OF TEMPS LOW TNGT/TMRW WITH CONTINUED CLOUDS AND
NWLY WINDS. MID/UPPER LEVEL RIDGE AND SFC HIGH PRESSURE APPROACHES
BY MON...WITH SFC RIDGE AXIS OVER THE CWA MON EVNG THROUGH TUES
MRNG. CLEARING SKIES AND WEAK WINDS...WITH FRESH DEEP SNOW
PACK...SHOULD ALLOW TEMPS TO PLUNGE ON MON NT...AND HAVE LOWERED
MOST LOCATIONS A COUPLE OF DEGREES TO KEEP MOST OF THE CWA BELOW
ZERO AND AT LEAST A FEW DEGREES BELOW GUDIANCE. CLEARING WILL BE
SHORT-LIVED AS UPPER WAVE DIGS INTO THE SW. RESULTING SWLY FLOW
ALOFT...AND RETURN FLOW AT THE SFC...SHOULD HELP TEMPS RECOVER INTO
THE 20S ON TUES.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
LONG TERM PERIOD BEGINS WITH A UPPER TROUGH IN THE SOUTHERN ROCKIES
WHICH GRADUALLY SHIFTS EAST INTO THE OHIO VALLEY AND DEEPENS FOR THE
WEEKEND. LEAD SHORTWAVE EJECTING INTO THE PLAINS TUESDAY NIGHT AND
WEDNESDAY HAS BEEN CONSISTENTLY ADVERTISED BY MODELS OVER THE LAST
COUPLE OF DAYS...SO CONFIDENCE HAS INCREASED IN CHANCE FOR SNOW
THEN. THUS HAVE INCREASED POPS ACROSS ALL OF THE CWA...BUT
MAINTAINED HIGHEST CHANCES IN THE SOUTH NEARER SHORTWAVE TRACK.
LIGHT SNOW SHOULD END WEDNESDAY AS SHORTWAVE SWINGS EAST. NORTH
WINDS ON BACK SIDE OF SYSTEM WILL COOL THINGS OFF FOR
THURSDAY...WITH HIGHS IN THE TEENS FOR MOST OF THE AREA. EVEN COLDER
CONDITIONS LOOK LIKELY FRIDAY INTO SATURDAY AS LARGE TROUGH IS
CARVED OUT IN THE GREAT LAKES AND OHIO VALLEY. MOST LONG RANGE
MODELS CONCUR WITH THIS PATTERN...PUTTING OUR CWA UNDER A STEADY
STREAM OF COLD SURGES AT LEAST INTO SATURDAY. TEMPERATURES WILL
LIKELY HOLD IN THE TEENS OR SINGLE DIGITS FOR HIGHS WITH LOWS
DROPPING BELOW ZERO.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
GENERALLY MVFR CIGS AND OCCASIONAL IFR VSBYS IN -SN CAN BE EXPECTED
THROUGH SUNDAY MORNING. SEVERAL WAVES OF LIGHT SNOW WILL ROTATE
AROUND EXPANSIVE UPPER LOW MOVING INTO THE MISSISSIPPI VALLEY. THE
WORST CONDITIONS WILL BE IN THESE SNOW BANDS WITH VISIBILITIES
DROPPING TO A MILE AT TIMES. NORTHWEST WINDS 20 TO 30 KTS WILL
GRADUALLY DIMINISH INTO THE 10 TO 20 KT RANGE BETWEEN 00Z AND 12Z
SUNDAY.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR NEZ011-
012-015>018-030>034-042>045-050>053-065>068-078-088>093.
IA...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR IAZ043-
055-056-069-079-080-090-091.
&&
$$
SHORT TERM...MAYES
LONG TERM/AVIATION...DERGAN
