FXUS63 KOAX 010958
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
358 AM CST TUE FEB 1 2011
.DISCUSSION...
...SNOWFALL AMOUNTS THE MAIN CHALLENGE...FOLLOWED BY WIND CHILLS...
MAIN UPPER LOW WAS DEEPENING OVER WEST TEXAS EARLY THIS MORNING
PER WATER VAPOR LOOP WITH CYCLONE GENERATING VERY STRONG LIFT
ACROSS SOUTHERN PLAINS. OVER THE CENTRAL PLAINS...ARCTIC AIRMASS
CONTINUES TO BUILD IN...WITH 1053 MB SURFACE HIGH OVER NORTHERN
MONTANA. ACTUAL TEMPERATURE UNDER THE HIGH WAS -36F AT HAVRE
MONTANA AT 08Z. SURFACE PRESSURE ANALYSIS CONTINUES TO SHOW A WEAK
INVERTED TROF OVER WESTERN IOWA. AIRMASS TO THE EAST OF THE
INVERTED TROF WAS CONSIDERABLY WARMER WITH TEMPERATURES IN THE
TEENS AND A NORTHEAST WIND...AND TO THE WEST OF THE TROF
TEMPERATURES WERE NEAR OR BELOW ZERO WITH A NORTHWEST WIND GUSTING
TO 30+ MPH.
ADJUSTMENTS MADE TO THE PREVIOUS FORECAST WERE MAINLY TO LOWER THE
SNOWFALL AMOUNTS BASED ON SEVERAL FACTORS. THE PRIMARY ISSUE WAS A
LACK OF AMBIENT OR UPSTREAM MOISTURE TO WORK WITH...AS WELL AS ONLY
MARGINAL VERTICAL MOTION. APPEARS THAT EARLIER MODELS WERE TOO
ROBUST WITH THEIR QPF AMOUNTS...NOTING THAT THE QPF FROM THE 12Z
RUNS WAS PROGGED TO BE NEARLY DOUBLE WHAT HAD OCCURRED IN THE 18
HOUR PERIOD THROUGH 06Z. IN ADDITION...SNOW GROWTH TEMPERATURES ARE
TOO COLD FOR DENDRITIC FLAKES. HOWEVER...STILL EXPECT TWO MAIN
PERIODS OF A FAIRLY LARGE AREA OF LIGHT SNOW. FIRST IS OCCURRING
NOW AND STRETCHES TO THE SOUTHWEST OVER NORTH CENTRAL KANSAS.
SECOND IS EXPECTED TO DEVELOP EARLY AFTERNOON. BOTH OF THESE AREAS
WILL FOCUS MORE ALONG INTERSTATE-80 AND AREAS SOUTH. 00Z NAM SEEMED
TO REPRESENT THESE AREAS WELL.
AS UPPER LOW MOVES NEAR ST LOUIS BY 06Z TONIGHT...TROWAL FORMS BUT
GENERALLY REMAINS EAST OF FORECAST AREA. HOWEVER THE SURFACE LOW
SHOULD DEEPEN WHILE THE ARCTIC HIGH MOVES SOUTH...THUS WINDS WILL
CONTINUE TO STRENGTHEN. GUSTY WINDS WILL DROP WIND CHILLS AND CAUSE
BLOWING AND DRIFTING SNOW. GIVEN THE COMBINATION OF SNOW...BLOWING
SNOW...AND WIND CHILLS... WE KEPT THE WINTER STORM WARNING MAINLY
ALONG AND SOUTH OF INTERSTATE 80 THROUGH 04Z TONIGHT...THEN COVER
THAT AREA WITH A WIND CHILL ADVISORY FROM 04Z THROUGH 18Z. THE
NORTHERN HALF OF THE AREA WILL ONLY RECEIVE ANOTHER 1 INCH OF SNOW
OR LESS...AND THEREFORE THOSE COUNTIES HAVE A WINTER WEATHER
ADVISORY UNTIL 04Z TONIGHT...THEN A WIND CHILL WARNING FROM 04Z
THROUGH 18Z WEDNESDAY.
NIETFELD
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
CONDS ARE EXPECTED TO BE GENERALLY MVFR TODAY WITH VFR CONDS FM THIS
EVNG. A BREAK IN THE -SN IS EXPECTED EARLY THIS MRNG AT ALL 3 TAF
LOCATIONS...AND THIS MAY LEAD TO A PERIOD OF VFR CONDS WITH JUST
BLSN. -SN EXPECTED TO RETURN TO OMA/LNK BY LATE MRNG AND CONT THRU
THE AFTN ALNG WITH BLSN. AS WINDS INCREASE TODAY...MAY SEE ISO
POCKETS OF IFR VISBY AT ALL SITES DUE TO BLSN. THE -SN AND BLSN WL
DIMINISH THIS EVNG WITH VFR CIGS AND VISBY EXPECTED.
BOUSTEAD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WINTER STORM WARNING UNTIL 10 PM CST THIS EVENING FOR NEZ045-
050>053-065>068-078-088>093.
WIND CHILL ADVISORY FROM 10 PM THIS EVENING TO NOON CST
WEDNESDAY FOR NEZ045-050>053-065>068-078-088>093.
WINTER WEATHER ADVISORY UNTIL 10 PM CST THIS EVENING FOR NEZ011-
012-015>018-030>034-042>044.
WIND CHILL WARNING FROM 10 PM THIS EVENING TO NOON CST WEDNESDAY
FOR NEZ011-012-015>018-030>034-042>044.
IA...WINTER STORM WARNING UNTIL 10 PM CST THIS EVENING FOR IAZ055-056-
069-079-080-090-091.
WIND CHILL ADVISORY FROM 10 PM THIS EVENING TO NOON CST
WEDNESDAY FOR IAZ055-056-069-079-080-090-091.
WINTER WEATHER ADVISORY UNTIL 10 PM CST THIS EVENING FOR IAZ043.
WIND CHILL WARNING FROM 10 PM THIS EVENING TO NOON CST WEDNESDAY
FOR IAZ043.
&&
$$