FXUS63 KOAX 142056
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
256 PM CST TUE DEC 14 2010
.SHORT TERM...TONIGHT THROUGH FRIDAY.
MAIN CONCERNS ARE TEMPERATURES THE NEXT FEW DAYS AND THE CHANCE FOR
PCPN WEDNESDAY INTO WEDNESDAY NIGHT. KEPT POPS ON THE LOW SIDE AT
THIS TIME...USING A BLEND OF MODEL SOLUTIONS FOR THE EVENT. AMOUNT
OF SNOW AND OR FREEZING RAIN APPEARS TO BE LOW AT THIS TIME AND
PROBABLY NOT ENOUGH TO CAUSE PROBLEMS.
STRONG 300 MB JET OF AROUND 175 KTS WAS SHOWN OFF THE COAST OF OR
AND NRN CA AT 12Z. THIS CONTINUED TO PUNCH EWD EARLY THIS AFTN WITH
SOME CLOUD TO GROUND LIGHTNING NOTED IN THE PACIFIC NW THIS MORNING.
12 HOUR 500 MB HEIGHT FALLS OF UP TO 200 METERS WERE NOTED AT KUIL
AND FALLS OF UP TO 50 METERS WERE NOTED AS FAR EAST AS NRN AZ...
UT AND WRN MT. SO THE WEAK RIDGING OVER THE WRN HIGH PLAINS SHOULD
CONTINUE TO FLATTEN. SURFACE ANALYSIS EARLY THIS AFTN SHOWED A LOW
PRES TROUGH FROM CNTRL MT INTO NERN NM AND A RIDGE OF HIGH PRES FROM
ERN MN INTO MS AND AR. SOUTH OR SOUTHEAST WINDS WILL DOMINATE THE
AREA OVERNIGHT...AND ATTEMPT TO KEEP TEMPERATURES UP. THE AMOUNT OF
CLOUD COVER AND CURRENT SNOW ON THE GROUND IN SOME AREAS WILL HELP
ADD TO THE UNCERTAINTY. WINDS APPEAR STRONG ENOUGH SO DECOUPLING OF
THE NEAR SURFACE LAYER IS UNLIKELY. A BLEND OF THE CURRENT FORECAST
AND 12Z NAM GUIDANCE SEEMS REASONABLE. GFS MOS APPEARS TOO COLD...
UNLESS SURFACE WINDS ARE LIGHTER THAN EXPECTED. 18Z NAM SUGGESTS A
BIT OF SLEET OR LIGHT FREEZING RAIN IS POSSIBLE FROM WAYNE TOWARD
TEKAMAH AND HARLAN AFTER MIDNIGHT TONIGHT...SO INCLUDED A SLIGHT
CHANCE THOSE AREAS 06Z TO 12Z.
LOW LEVEL WARM AIR ADVECTION IS EXPECTED TO CONTINUE WEDNESDAY...
WITH FAIRLY THICK HIGH LEVEL CLOUD COVER. THERE SHOULD ALSO BE AN
INCREASE IN LOW AND MID LEVEL MOISTURE IN THE AFTERNOON. KEPT POPS
AT 24 PERCENT OR LESS FOR NOW...WITH SOME DRY AIR INDICATED IN THE
850 MB TO 700 MB LAYER WHICH WILL CAUSE AT LEAST SOME OF THE PCPN
GENERATED IN THE MID LEVELS TO RESULT IN VIRGA. FORECAST SOUNDINGS
SUGGEST MIXED PCPN WITH WARM LAYER ALOFT WEDNESDAY AFTERNOON AND
EVENING.
MODELS SHOW VARYING AMOUNTS OF LOW LEVEL MOISTURE ACROSS THE AREA
LATER WEDNESDAY NIGHT INTO EARLY THURSDAY. 12Z GFS INDICATED A
VERY SHALLOW LAYER OF MOISTURE...PROBABLY NOT DEEP ENOUGH FOR
PCPN. BOTH THE 12Z AND 18Z RUNS OF THE NAM INDICATED A SLIGHTLY
DEEPER LAYER...ENOUGH FOR SOME FLURRIES OR FREEZING DRIZZLE. WE
WILL CONTINUE TO KEEP AN EYE ON THAT BUT FOR NOW IT DID NOT LOOK
SIGNIFICANT. OTHERWISE BELOW NORMAL TEMPERATURES WILL CONTINUE
THURSDAY AND FRIDAY ALONG WITH MAINLY DRY CONDITIONS.
.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY.
GENERALLY PERSISTENT UPPER PATTERN INDICATED FOR THE EXTENDED
PORTION OF THE FORECAST WITH TROUGH OVER THE EASTERN CONUS AND
RIDGING FROM THE INTERMOUNTAIN REGION TO THE WESTERN HIGH PLAINS.
LITTLE DAY TO DAY CHANGE REGARDING TEMPERATURES WITH THE AREA
STAYING BETWEEN THESE TWO FEATURES. SOME UNCERTAINTY WITH PRECIP
HOWEVER AS WEAK WAVES MOVE THROUGH THE NORTHWEST FLOW ACROSS THE
REGION. PREDOMINATELY DRY FOR NOW BUT SOME LIGHT PRECIP NOT OUT OF
THE QUESTION AROUND SUNDAY NIGHT INTO MONDAY MORNING PER GFS. WILL
SEE HOW LATER RUNS HANDLE THINGS BEFORE INTRODUCTION INTO
FORECAST.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
THE MID LEVEL RIDGE OVER THE HIGH PLAINS WILL SHIFT EASTWARD TO THE
MISSOURI VALLEY BY 18Z WEDNESDAY. MEANWHILE...A LARGE AREA OF MID
AND HIGH CLOUDS OVER THE WESTERN THIRD OF THE U.S. WILL CONTINUE TO
STREAM EASTWARD. WE CONTINUE TO EXPECT VFR CONDITIONS AT THE TAF
SITES WITH MAINLY HIGH CLOUDS THROUGH 06Z...AND THICKENING MID CLDS
AFTER 06-09Z. COULD SEE SOME MVFR CIGS DEVELOP AFT 15Z...BUT DID
NOT HAVE ENOUGH CONFIDENCE TO INCLUDE AS THE CDFNT WAS STILL TO THE
WEST OF THE CWA AND THE SOUTHEAST FLOW WILL GENERALLY BE FROM 8 TO
14 KTS THRU THE PD.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
SHORT TERM...MILLER
LONG TERM....FOBERT
AVIATION...ZAPOTOCNY