FXUS63 KOAX 290953
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
348 AM CST SAT JAN 29 2011
.DISCUSSION...
SYNOPSIS...0000 UNIVERSAL COORDINATED TIME ANALYSIS INDICATED A
SHORT-WAVE TROUGH OVER WESTERN BRITISH COLUMBIA. THIS SYSTEM WAS
ASSOCIATED WITH AROUND 120 METER 500 HECTOPASCALS HEIGHT FALLS OVER
WESTERN BRITISH COLUMBIA. DOWNSTREAM FROM THE SHORT-WAVE
TROUGH...A LOW-AMPLITUDE RIDGE EXTENDED ACROSS THE HIGH PLAINS.
AT 850 HECTOPASCALS...A LOW WAS LOCATED NEAR INTERNATIONAL FALLS
WITH A COLD FRONT SOUTHWEST INTO WESTERN SOUTH DAKOTA. THE 0800
UNIVERSAL COORDINATED TIME SURFACE ANALYSIS INDICATED A 1006
MILLIBAR LOW OVR EASTERN WISCONSIN WITH A TRAILING COLD FRONT INTO
NORTHERN IOWA AND EASTERN SOUTH DAKOTA.
FORECAST...THE SHORT TERM CONCERNS CONTINUE TO CENTER AROUND
PRECIPITATION CHANCES OVER THE NEXT SEVERAL DAYS...AND ALSO WITH
TEMPERATURES. FOR TODAY THE COLD FRONT OVER NORTHERN IOWA AND
EASTERN SOUTH DAKOTA WILL CONTINUE TO MOVE SOUTH ALONG WITH
COOLER TEMPERATURES AND THE STRATUS DECK LOCATED BEHIND THE FRONT.
TEMPERATURES ARE STARTING OUT RATHER WARM THIS MORNING AND THUS
HAVE INCREASED HIGHS FOR TODAY WITH A POSSIBLE QUICK JUMP IN
TEMPERATURES. THIS WOULD OCCUR BEFORE THINGS START TO LEVEL OFF
THIS AFTERNOON AS CLOUDS AND COOLER AIR MOVE IN. THE PREVIOUSLY
MENTIONED SHORT-WAVE TROUGH /LOCATED OVER WESTERN BRITISH COLUMBIA
AT 0000 UNIVERSAL COORDINATED TIME/ IS EXPECTED TO MOVE ACROSS
SOUTH DAKOTA AND INTO IOWA TODAY. LARGE-SCALE ASCENT DOES INCREASE
ACROSS OUR NORTHERN COUNTY WARNING AREA AROUND 1800 UNIVERSAL
COORDINATED TIME...BUT THE MIDDLE LEVELS OF THE ATMOSPHERE APPEAR TO
REMAIN DRY...AND THUS WE HAVE REMOVED THE SLIGHT CHANCE OF
PROBABILITY OF PRECIPITATION FROM THIS AFTERNOON. WE STILL MAY SEE A
FEW FLURRIES...BUT MEASURABLE PRECIPITATION APPEARS UNLIKELY.
THE CANADIAN SURFACE HIGH PRESSURE WILL BUILD SOUTHWARD THROUGH
THE MISSOURI RIVER VALLEY TONIGHT. LOWS WILL BE DEPENDENT ON THE
AMOUNT OF CLOUD COVER...BUT UPSTREAM TEMPERATURES THIS MORNING
WOULD INDICATE A TOUCH COOLER THAN OUR CURRENT FORECAST HAD GOING.
A COMBINATION OF UPPER-LEVEL SYSTEMS WILL START TO MOVE INTO AND
THROUGH THE WESTERN UNITED STATES ON SUNDAY. THIS WILL ACT TO
BACK THE MID AND UPPER LEVEL FLOW TO THE WEST AND THEN SOUTHWEST
LEADING TO WARM AIR ADVECTION. WE BELIEVE MOST OF SUNDAY AND
SUNDAY EVENING WILL BE DRY AS MOISTURE WILL BE LACKING...BUT
CLOUDS WILL CERTAINLY BE ON THE INCREASE. WITH THE SURFACE RIDGE
AXIS NEAR THE COUNTY WARNING AREA AND A GOOD DEAL OF CLOUDS...WE
ARE EXPECTED A PRETTY CHILLY DAY /ESPECIALLY IN THE NORTHWEST
FORECAST AREA/. THE PRECIPITATION CHANCES CONTINUE TO LOOK TO
INCREASE AFTER MIDNIGHT ON SUNDAY AS A WEAK SHORT-WAVE TROUGH IS
PROJECTED TO EJECT EASTWARD ALONG THE TIGHT MIDDLE ATMOSPHERE
TEMPERATURE GRADIENT. THIS CONTINUES TO LOOK TO INCREASE ASCENT
AND EVENTUALLY LEAD TO LIGHT SNOW. WILL MAINTAIN THE LIKELY
PROBABILITY OF PRECIPITATION OVER THE NORTHERN COUNTY WARNING
AREA...BUT HAVE DECREASED THE PROBABILITY OF PRECIPITATION OVER THE
SOUTHERN FORECAST AREA AS LIFT APPEARS TO BE LACKING.
THE FORECAST FROM MONDAY THROUGH WEDNESDAY CONTINUES TO LOOK
TRICKY. THE MODELS CONTINUE TO STRUGGLE WITH HOW THE NORTHERN AND
SOUTHERN STREAM SYSTEMS WILL INTERACT OR PHASE WITH ONE ANOTHER.
THE GLOBAL FORECAST SYSTEM CONTINUES TO BE AN OUTLIER AND WE WILL
GENERALLY DISCOUNT THIS MODEL AT THE MOMENT. THE EUROPEAN CENTRE
FOR MEDIUM RANGE FORECAST MODEL MAINTAINS SOME CONTINUITY...BUT
HAS SHIFTED A TOUCH SOUTH AND EAST WITH THE SOUTHERN STREAM 500
HECTOPASCALS TROUGH AS IT MOVES THROUGH THE CENTRAL PLAINS. THIS
SEEMS TO AGREE FAIRLY WELL WITH THE GLOBAL ENVIRONMENTAL
MULTISCALE MODEL...AND THUS A MIX OF THESE TWO MODELS IS PREFERRED
AT THIS TIME. THIS LINE OF THOUGHT ALSO HAS SOME SUPPORT FROM THE
NORTH AMERICAN MESOSCALE MODEL AND THE SHORT RANGE ENSEMBLE
FORECAST SYSTEM. THUS IT APPEARS THE COUNTY WARNING
AREA...ESPECIALLY ALONG AND SOUTH OF INTERSTATE 80...IS IN FOR
ANOTHER LONG DURATION LIGHT SNOW EVENT. FRONTOGENESIS IS EXPECTED
TO INCREASE THROUGH THE DAY ON MONDAY LEADING TO PRECIPITATION BY
AFTERNOON AND HAVE INCREASED PROBABILITY OF PRECIPITATION TO THE
LIKELY CATEGORY FOR MOST OF THE COUNTY WARNING AREA. ALTHOUGH
THERE MAY BE SOME BRIEF BREAK IN THE LIGHT SNOW...FAIRLY STEADY
LIGHT SNOW IS THEN EXPECTED THROUGH MONDAY NIGHT AND THE DAY ON
TUESDAY...AND HAVE ALSO INCREASED PROBABILITY OF PRECIPITATION TO
LIKELY IN THESE PERIODS OF THE FORECAST AS WELL. LOCAL IMPACT MAY
INCREASE THOUGH THROUGH THE DAY ON TUESDAY AS 1050 MILLIBAR ARCTIC
HIGH PRESSURE STARTS TO BUILD SOUTHWARD AND INCREASES THE SURFACE
PRESSURE GRADIENT AND LEAD TO STRONGER WINDS. THIS MAY TEND TO
LEAD TO AREAS OF BLOWING SNOW ON TUESDAY AND TUESDAY NIGHT. THE
LIGHT SNOW SHOULD TAPER FROM NORTH TO SOUTH ON TUESDAY NIGHT WITH
THE MAJORITY OF THE FORECAST SEEING DRY CONDITIONS BY MIDDLE OF
THE MORNING WEDNESDAY. ONLY OTHER CHANGES WERE TO INCREASE THE
HIGHS AND LOWS OVER THE CENTRAL AND EASTERN COUNTY WARNING AREA
FROM MONDAY THROUGH TUESDAY NIGHT AHEAD OF THE SURFACE INVERTED
TROUGH.
BOUSTEAD
&&
.AVIATION...
TERMINAL AERODROME FORECAST FOR SITES KOFK/KOMA/KLNK
0600 UNIVERSAL COORDINATED TIME TERMINAL AERODROME FORECAST
VISUAL FLIGHT RULES CONDITIONS WILL DETERIORATE THROUGH THE DAY
TO MARGINAL VISUAL FLIGHT RULES AND EVENTUALLY INSTRUMENT FLIGHT
RULES AS LOW CEILINGS PUSH SOUTHWARD OUT OF SOUTH DAKOTA/MINNESOTA
INTO NEBRASKA. KOFK WILL SEE DETERIORATING CEILINGS EARLIEST /BY LATE
MORNING/...FOLLOWED BY KOMA AND KLNK /THROUGH THE AFTERNOON/.
LIGHT/VARIABLE WINDS WILL GIVE WAY TO NORTHERLY WINDS AROUND 10
KNOTS THIS AFTERNOON...CONTINUING THROUGH THE REST OF THE TERMINAL
AERODROME FORECAST CYCLE.
MAYES
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$