FXUS63 KOAX 172034
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
234 PM CST THU FEB 17 2011
.SHORT TERM...TONIGHT THROUGH SUNDAY. MAIN WEATHER CONCERN THROUGH
THE PERIOD WILL BE SATURDAY NIGHT AND SUNDAY AS A NEW LOW PRESSURE
SYSTEM MOVES ONTO THE CENTRAL PLAINS. MOISTURE ADVECTING NORTHWARD
SHOULD LEAD TO AT LEAST ISOLATED SHOWERS BY SATURDAY AFTERNOON
WITHIN THE WARM AIR ADVECTION REGIME. A MORE SUBSTANTIAL THREAT
FOR RAIN COMES SATURDAY NIGHT AS LOW LEVEL JET STRENGTHENS...COMBINED
WITH THE NORTHWARD ADVANCE OF A SURFACE WARM FRONT...AS THE UPPER
LEVEL JET APPROACHES FROM THE WEST. LATEST DETERMINISTIC MODELS
ARE NOW TRENDING A LITTLE FURTHER WEST...WHICH PUTS MOST OF THE
FORECAST AREA SOLIDLY WITHIN THE WARM SECTOR...SUGGESTING A RAIN
EVENT SATURDAY NIGHT AND ADJUSTED FORECAST ACCORDINGLY. HOWEVER...
IN NORTHEAST NEBRASKA...SURFACE TEMPS COULD DIP TOWARD FREEZING
BY SUNDAY MORNING...THUS THERE COULD BE PATCHY FREEZING RAIN
NORTHWEST OF A LINE FROM KOLU TO KLCG. DID INCREASE PROBABILITY
FOR PRECIP SATURDAY NIGHT AND SUNDAY INTO THE LIKELY CATEGORY...AND
ALSO ADDED IN ISOLATED THUNDERSTORMS AS ALL MODELS ALSO INDICATING
SOME WEAK INSTABILITY WITH NEGATIVE 850MB LIFTED INDEX VALUES
SPREADING THROUGH THE REGION WITHIN THE WARM SECTOR AS WELL. WITH
THE SURFACE LOW TAKING A SLIGHTLY MORE WESTERN AND NORTHERN
TRACK...THIS PUSHES ANY AXIS OF HEAVIER SNOW POTENTIAL FURTHER
NORTH INTO SOUTH DAKOTA AND NORTHWEST IOWA AS WELL. WITH THE
SURFACE LOW PULLING OFF TO THE NORTHEAST ON SUNDAY...WE WILL
EXPERIENCE COLDER AIR BEGINNING TO FILTER INTO AT LEAST NORTHEAST
NEBRASKA...WHICH SHOULD SWITCH ANY LINGERING PRECIPITATION OVER TO
SNOW...BUT BY THEN THE BULK OF THE MEASURABLE PRECIP SHOULD BE
FURTHER NORTH AND NOT CAUSE SIGNIFICANT PROBLEMS FOR OUR AREA.
MEANWHILE...COLDER AIR DOESN'T REALLY ARRIVE ALONG/SOUTH OF THE
INTERSTATE UNTIL SUNDAY NIGHT.
70
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY. PERIOD BEGINS WITH
BOTH THE GFS AND EURO SHOWING MUCH COLDER AIR SPILLING BACK INTO
THE AREA WITH SOME CHANCE OF LIGHT SNOW SUNDAY NIGHT INTO EARLY
MONDAY. COLDER TEMPERATURES LOOK SHORT LIVED AT THIS TIME HOWEVER
AS SURFACE HIGH PRESSURE SHIFTS EAST ON TUESDAY WITH RETURN FLOW
SETTING UP IN ADVANCE OF THE NEXT WAVE COMING INTO THE PACIFIC
NORTHWEST. MORE UNCERTAINTY CREEPS INTO THE FORECAST WEDNESDAY
INTO THURSDAY AS MODELS SHOW MORE VARIATION REGARDING NEXT UPPER
WAVE COMING INTO THE NORTHWEST AND ASSOCIATED COLD AIR INTRUSION
BEHIND THE COLD FRONT. FOR NOW HAVE TRENDED TOWARD HPC GUIDANCE
AND THE SLOWER AND WARMER EURO. LOOKS LIKE COLDER AIR WILL MAKE IT
BACK INTO THE AREA JUST A MATTER OF WHEN.
FOBERT
&&
.HYDROLOGY...
AN ICE JAM OCCURRED ALONG THE PLATTE RIVER EARLIER THIS MORNING
AND FLOOD WARNINGS WERE ISSUED VALID THROUGH 4 PM FOR SOME MINOR
FLOODING NEAR ASHLAND AND CEDAR CREEK. IT APPEARS THAT THE ICE
THAT CAUSED THE JAM HAS FLUSHED OUT PUSHING DOWNSTREAM TOWARD THE
MISSOURI AND THOSE WARNINGS WILL LIKELY BE ALLOWED TO EXPIRE.
ANOTHER ICE JAM ON THE ELKHORN RIVER AT PILGER WAS BEGINNING TO
AFFECT THE RIVER BETWEEN PILGER AND WEST POINT. THERE HAVE ALSO
BEEN BAD GAGE READINGS AT BOTH SIGHTS AT THE USGS IS ONSITE
REPAIRING THOSE AT THE MOMENT. A FLOOD ADVISORY WAS ISSUED FOR
THAT STRETCH FOR MINOR RURAL LOWLAND FLOODING ALONG THE RIVER
BANKS.
WITH CONTINUED WARMTH...HOPEFULLY WE CAN CONTINUE TO FLUSH OUT ICE
DOWNSTREAM OVER THE NEXT COUPLE OF DAYS. ADDITIONAL RAINFALL EXPECTED
THIS WEEKEND IS SLIGHTLY CONCERNING. AT THIS TIME...RAINFALL AMOUNTS
LESS THAN ONE HALF INCH ARE FORECAST. NOT SURE THIS WILL BE ENOUGH
TO CAUSE ANY ADDITIONAL WIDESPREAD PROBLEMS.
WITHIN BANK RISES ARE ALSO FORECAST ALONG THE NISHNABOTNA RIVER IN
SOUTHWEST IOWA.
70
&&
.FIRE WEATHER...
SURFACE DEWPOINTS HAVE MIXED DOWN INTO THE UPPER TEENS ACROSS
NORTH CENTRAL AND NORTHEAST NEBRASKA THIS AFTERNOON. THIS HAS
RESULTED IN RELATIVE HUMIDITY VALUES DROPPING TO AROUND OR JUST
BELOW 20 PERCENT. WITH GUSTY NORTHWEST WINDS...THERE IS A VERY
HIGH TO EXTREME FIRE DANGER THERE THIS AFTERNOON...HOWEVER FUELS
MAY STILL BE SLIGHTLY WET FROM RECENT SNOW AND CONDITIONS SHOULD
IMPROVE TOWARD SUNSET.
70
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
VFR CONDITIONS WILL PREVAIL THROUGH THE FORECAST PERIOD. FRONTAL
PASSAGE/WIND SHIFT TO THE NORTHWEST HAS ALREADY OCCURRED AT KOFK.
AT KOMA AND KLNK WIND SHIFT TO NORTHWEST AROUND 21Z THIS AFTERNOON
WITH GUSTS AROUND 25KT EXPECTED UNTIL 18/00Z.
DEE
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$