FXUS63 KOAX 242127
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
327 PM CST WED NOV 24 2010
.SHORT TERM...TONIGHT THROUGH SATURDAY.
STRONG COLD FRONT WAS MOVING THROUGH THE CWA THIS
AFTERNOON...USHERING IN MUCH COLDER AIR ORIGINATING FROM THE
CANADIAN PRAIRIES. A 40-DEGREE TEMPERATURE DIFFERENCE WAS NOTED
BETWEEN NORTHEAST NEBRASKA AND SOUTHEAST NEBRASKA EARLIER THIS
AFTERNOON. SINGLE DIGIT TEMPERATURES IN WESTERN SOUTH DAKOTA SHOULD
SURGE SOUTH TONIGHT WITH AT LEAST THE NORTHERN CWA BELOW 10 BY
MORNING. THICK CLOUD COVER ALONG AND BEHIND THE FRONT CONTAINED
LIGHT DRIZZLE IN AREA OF WEAK LIFT AHEAD OF MID LEVEL SHORTWAVE
TROUGH MOVING THROUGH CENTRAL NEBRASKA. LOW CLOUDS WERE BEING
SCOURED OUT BEHIND THE SHORTWAVE...BUT CLOUDS AND DRIZZLE WILL
CONTINUE IN OUR EASTERN CWA THROUGH THE EVENING DRIVE TIME.
TEMPERATURES WILL BE DROPPING BELOW FREEZING AS WELL...SO AREAS OF
FREEZING DRIZZLE IS LIKELY FOR MUCH OF THE AREA FROM THE
OMAHA/COUNCIL BLUFFS METRO AND NORTH. GIVEN THAT IT IS A PEAK
HOLIDAY TRAVEL TIME...AND REPORTS OF PATCHY ICY CONDITIONS IN
NORTHEAST NEBRASKA...WILL HOIST A FREEZING RAIN/DRIZZLE ADVISORY FOR
THE OMAHA METRO AND POINTS NORTH INTO THE EVENING.
COLD ADVECTION CONTINUES ON THANKSGIVING DAY SHOWN BY 850 TEMPS
DROPPING ANOTHER COUPLE OF DEGREES OR SO THROUGH THE DAY. NAM IS
MORE ROBUST WITH THIS COOLING...BUT GFS IS ONLY A CATEGORY HIGHER IN
FORECAST SURFACE TEMPERATURES. MUCH OF THE CWA WILL SEE PLENTY OF
SUNSHINE THURSDAY...BUT THE NORTH WILL LIKELY SEE THICKENING CLOUDS
AS WAVE ROLLS THROUGH THE NORTHERN PLAINS. GIVEN HIGH HUMIDITY IN
DENDRITIC TEMPERATURE LAYER IN THE NORTHERN CWA...HAVE INSERTED
FLURRIES THERE. TEMPS MAY HOLD IN THE TEENS WHERE CLOUDS REMAIN WITH
20S OVER MUCH OF THE REST OF THE AREA.
WESTERLY LOW LEVEL FLOW WILL CONTINUE OVER MID AMERICA THURSDAY
NIGHT INTO SATURDAY MORNING WITH GRADUALLY WARMING LOW LEVEL
TEMPERATURES. CLOUD COVER LOOKS TO BE MINIMAL...SO EXPECT INVERSION
AND RADIATIONAL COOLING TO KEEP LOWS RATHER COOL BOTH FRIDAY AND
SATURDAY MORNINGS. HAVE FOLLOWED SIMILAR MAV/MET NUMBERS AND KNOCKED
OFF A FEW DEGREES IN NORMAL COOL SPOTS. MOST LOWS SHOULD RANGE IN
THE LOWER TEENS FRIDAY MORNING AND NEAR 20 SATURDAY MORNING. HIGHS
SHOULD REBOUND TOWARD 40 FRIDAY AND MID 40S SATURDAY GIVEN PLENTY OF
SUNSHINE. STRONGER WARM ADVECTION SATURDAY COULD EVEN BOOST TEMPS
CLOSER TO 50.
DERGAN
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY.
REGION WILL BE QUIET INITIALLY AS AN UPPER RIDGE AXIS MOVES OVERHEAD
THRU EARLY SUNDAY IN ADVANCE OF A LARGE UPPER TROF SWINGING OUT OF
THE SOUTHWESTERN CONUS. MEDIUM RANGE MODELS ARE STILL NOT IN GOOD
AGREEMENT WITH TIMING AND POSITIONING OF THE TROF...SO WE HAVE GONE
CLOSE TO HPC'S GUIDANCE WHICH IS TO BASE THE FORECAST MORE CLOSELY
TO THE 00Z ECMWF FOR THIS PACKAGE. THIS SOLUTION WOULD BRING THE
BASE OF THE UPPER TROF OVER THE FOUR CORNERS REGION BY 00Z MONDAY
WITH LEE SIDE SFC CYCLONE STRENGTHENING OVER ERN COLORADO. PCPN
WOULD DEVELOP ALONG TIGHT BAROCLINIC ZONE LATE SUNDAY NIGHT OVER THE
NRN CWA AND SLOWLY SPREAD EAST INTO MONDAY. PCPN LOOKS TO START OUT
AS RA EARLY...BUT WL QUICKLY TRANSITION OVER TO SNOW WITH STRONG
CAA. BY MONDAY NIGHT...LEAD SHORTWAVE ENERGY CLOSES OFF OVER THE CWA
TO PROVIDE ADDITIONAL LARGE SCALE LIFT INTO TUESDAY NIGHT AS THE
SYSTEM MOVES NORTHEAST. TEMPERATURE PROFILES WOULD SUPPORT SNOW AS
THE SYSTEM CONTINUES TO EXIT TO THE NORTHEAST EARLY TUESDAY. WL BE A
SYSTEM TO KEEP A CLOSE EYE ON AS TIGHT SFC PRESSURE GRADIENT BEHIND
THE SFC LOW COULD CREATE SOME BREEZY CONDITIONS IN ADDITION TO NEW
SNOWFALL. HAVE ONLY GONE WITH CHANCE POPS FOR NOW DUE TO THE
UNCERTAINTY OF MODEL TIMING AND POSITIONING OF THE SYSTEM.
KERN
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
COLD FRONT WILL RAPIDLY SWEEP ACROSS THE FORECAST AREA THROUGH 00Z
WITH A PERIOD OF IFR OR LIFR CIGS AND PATCHY FREEZING DRIZZLE
EXPECTED FOR A SHORT TIME BEHIND THE FRONT. CONDITIONS SHOULD
IMPROVE TO VFR AFTER 00Z AS COLDER AIR DEEPENS AND DRIER AIR WORKS
INTO THE AREA. STRONG NORTHWEST SURFACE WINDS WILL LINGER THROUGH
06Z THEN DIMINISH AS GRADIENT WEAKENS.
FOBERT
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...FREEZING RAIN ADVISORY UNTIL 9 PM CST THIS EVENING FOR NEZ015-
033-034-044-045-051>053.
FREEZING RAIN ADVISORY UNTIL 6 PM CST THIS EVENING FOR NEZ012-
017-018-031-032-042-043-050-065.
IA...FREEZING RAIN ADVISORY UNTIL 9 PM CST THIS EVENING FOR IAZ043-
055-056-069.
&&
$$