FXUS63 KOAX 132148
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
348 PM CST MON DEC 13 2010
.SHORT TERM...TONIGHT THROUGH THURSDAY.
FORECAST CONCERNS IN THE SHORT TERM WILL BE CHC FOR FLURRIES OR
LIGHT SNOW TONIGHT AND TUESDAY EVENING...THEN A BETTER CHANCE FOR
PRECIP AND TYPE WED INTO WED NIGHT.
STARTING OUT THIS AFTERNOON...THE LARGE MID TROPOSPHERIC TROUGH TO
OUR EAST WAS OVER NY/PA/VA...WHILE MUCH OF THE MIDWEST WAS UNDER
THE INFLUENCE OF NW FLOW ALOFT AND A MID LEVEL RIDGE WAS OVER THE
WESTERN THIRD OF THE U.S. AT THE SFC...COLD HIGH PRESSURE EXTENDED
FM MN INTO IA AND WEAK SFC FLOW OFF THE HIGH HAS KEPT TEMPS WELL
BELOW NORMAL IN THE TEENS AND 20S. HIGHER UP IN THE
ATMOSPHERE...THERE IS SOME MOISTURE BETWEEN H85 AND H60 AND WITH
WAA IN THIS MOIST LAYER...THERE HAVE BEEN QUITE A FEW CLOUDS OVER
THE AREA. ALTHOUGH THE CLOUDS WILL HOLD TEMPS UP...DEWPOINTS ARE
QUITE COLD AND HAVE LOWS MOSTLY IN THE SINGLE DIGITS. TONIGHT
INTO TUESDAY NIGHT...THERE ARE A COUPLE OF WEAK SHORTWAVES IN THE
NW FLOW ALOFT...ACCOMPANIED BY THE WAA AND FRONTOGENESIS. THIS MAY
RESULT IN SOME LIGHT SNOW OR FLURRIES AND HAVE THESE MENTIONED IN
THE NORTH TONIGHT AND IN WRN IA TUESDAY. TUESDAY NIGHT...ANOTHER
LIGHT BAND OF FLURRIES OR LIGHT SNOW COULD DEVELOP...BUT FOR NOW
HAVE THIS TO THE NORTH OF THE CWA. THE SFC HIGH GETS NUDGED
FARTHER EAST TO THE MISSISSIPPI RIVER TUES AND OVER WI WED.
ALTHOUGH THE MID LEVE RIDGE OVER THE ROCKIES MOVES INTO THE
PLAINS...IT FLATTENS. ALSO...THE COLD SOUTHEAST FLOW WILL HINDER A
BIG WARM UP. NEVER THE LESS...THIS SHOULD ALLOW AFTERNOON HIGH
TEMPERATURES TO MODERATE INTO THE 20S TUESDAY AND THE 20S AND 30S
WEDNESDAY. WED...THE TROF RESPONSIBLE FOR THE FLATTENING OF THE
RIDGE WILL MAKE TO TO MT WITH MOISTURE AND LARGE SCALE LIFT OVER
THE PLAINS STATES.
ALTHOUGH THE DETAILS STILL HAVE TO BE WORKED OUT...BOTH THE
NAM/GFS HAVE AN H85 FNT MOVE THROUGH AS THE MAIN SFC LOW TRACKS
ACRS TX. WITH THE COLDER SFC AIR IN PLACE AND THE MILD AIR
ALOFT...COULD BE SOME MIXED PRECIP AS THIS PARTICULAR SHORTWAVE
MOVES THROUGH WED AFT AND WED NIGHT. ALTHOUGH THE AXIS OF BETTER
PRECIP IS FROM THE DAKOTS INTO MN/IA SOUTHEASTWARD...THERE COULD
BE ANOTHER BAND FARTHER SOUTH...THUS DO HAVE POPS IN FOR THIS
PERIOD AND WILL HAVE TO REFINE AS WE GET A BETTER HANDLE ON THE
LOCATION OF THE FORCING. THE DIFFERENCES CARRY INTO THURSDAY AND
FOR NOW HAVE THE MID LEVEL FORCING TO THE EAST WITH DRIER NW FLOW
OVER THE CWA. IF THE STORM SYSTEM IS FARTHER WEST...WILL NEED TO
ADJUST THE PRECIP FARTHER WEST.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY.
OVERALL UPPER AIR PATTERN DURING THE LONG TERM PERIOD WILL BE
DOMINATED BY A TROUGH/LOW DRIFTING DOWN THE WEST COAST FROM THE GULF
OF ALASKA...AND ANOTHER LOW SPINNING NEAR NEW ENGLAND. THIS PATTERN
HOLDS PRETTY MUCH STEADY THROUGH MONDAY. HOWEVER MODELS ARE NOT
CLEAR WITH FLOW IN BETWEEN THESE MAJOR UPPER FEATURES...AND THUS
DETAILS ARE MURKY FOR OUR PART OF THE WORLD. IT DOES APPEAR THAT NO
MAJOR SWINGS IN TEMPS ARE IN STORE WITH A GENERALLY DRY FORECAST.
BOTH GFS AND ECMWF SHOW A WAVE MOVING THROUGH THE SOUTHERN PLAINS
FRIDAY AND FRIDAY NIGHT...BUT FAR ENOUGH SOUTH TO PRECLUDE PRECIP
MENTION. AND NOW THE 12Z GFS PAINTS A SWATH OF SNOW SATURDAY AND
SATURDAY NIGHT ACROSS NORTHERN NEBRASKA INTO IOWA IN WARM ADVECTION
REGIME AHEAD OF MINOR WAVE DROPPING OUT OF THE NORTHERN ROCKIES.
THIS IS A NEW FEATURE INTRODUCED WITH THIS RUN...AND HAS LITTLE IF
ANY SUPPORT FROM OTHER MODELS. SO WILL LEAVE MENTION OUT FOR NOW BUT
WILL KEEP AN EYE ON THIS FOR LATER FORECASTS.
TEMPERATURES WILL START THE PERIOD IN SINGLE DIGITS AND TEENS FOR
LOWS AND 20S FOR HIGHS...THEN GRADUALLY MODERATE THROUGH THE WEEKEND
TO LOWS NEAR 20 AND HIGHS IN THE 30S BY MONDAY.
&&
.AVIATION...
A WEAK DISTURBANCE/WARM ADVECTION WL MAINTAIN CIGS MOSTLY AOA 5K FT
AGL ACROSS TAF SITES THRU PERIOD. SOME LGT SNOW MAY ACCOMPANY THIS
DISTURBANCE ACROSS NRN NEBRASKA BUT IT APPEARS DRY LOW LVLS SHOULD
KEEP ANY SIGNIFICANT AMOUNT FROM REACHING THE GROUND AT TAF SITES.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
ZAPOTOCNY/DERGAN/FOBERT