Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 202104 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 304 PM CST SAT DEC 20 2014 .SHORT TERM...
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(TONIGHT THROUGH TUESDAY) ISSUED AT 255 PM CST SAT DEC 20 2014 ANOTHER CHANCE OF DRIZZLE/FREEZING DRIZZLE TONIGHT...THEN RAIN OR SNOW CHANCES SUNDAY NIGHT INTO MONDAY...ARE THE PRIMARY FORECAST CONCERNS. RELATIVELY ZONAL FLOW IN THE MIDDLE OF THE COUNTY WAS SEEN THIS MORNING...BETWEEN AN EXITING SHORTWAVE TROUGH SWINGING INTO THE GREAT LAKES AND ANOTHER WEAK TROUGH IN THE ROCKIES. EXITING TROUGH PRODUCED ENOUGH LIFT OVERNIGHT TO PRODUCE AREAS OF DRIZZLE ACROSS THE CWA WHERE TEMPERATURES HAD SLIPPED A COUPLE OF DEGREES BELOW FREEZING. MINOR IMPACTS TO SIDEWALKS AND ELEVATED SURFACE WERE SEEN...BUT NOT A HUGE TRAVEL HAZARD. EXPECT A REPEAT TO THE DRIZZLE SCENARIO TONIGHT AS ROCKIES TROUGH DEEPENS IN THE HIGH PLAINS...PUTTING OUR AREA UNDER CONTINUED WARM ADVECTION/LIFT OVER SATURATED SURFACE LAYER. TEMPERATURES SHOULD HOLD NEAR OR ABOVE FREEZING FOR THE MOST PART OVERNIGHT AS PERSISTENT LIGHT SOUTHERLY FLOW PUSHES DEW POINTS TO OR ABOVE FREEZING. EXPECT CLOUD COVER TO HANG TOUGH ACROSS THE CWA MUCH OF SUNDAY GIVEN CONTINUED SOUTHERLY LOW LEVEL FLOW AND INFLUX OF MOISTURE. HOWEVER WINDS WILL KICK UP A BIT MORE DURING THE AFTERNOON AND MAY TURN A TAD WEST OF SOUTH AS LOW PRESSURE DEEPENS IN THE HIGH PLAINS. THIS COULD SCOUR OUT CLOUDS IN A FEW AREAS...BUT PLAYING IT PESSIMISTIC ON THE SHORTEST DAY OF THE YEAR APPEARS PRUDENT. HIGHS SUNDAY WILL LIKELY RISE TO OR ABOVE 40 MOST AREAS. MID LEVEL LOW PRESSURE AREA IS FORECAST TO DROP OUT OF CANADA INTO EASTERN SOUTH DAKOTA SUNDAY NIGHT. BROAD ASCENT ON EAST SIDE OF TROUGH AXIS COMBINED WITH BETTER FORCING ASSOCIATED WITH APPROACHING UPPER LOW WILL LEAD TO INCREASING PRECIPITATION CHANCES ALONG SURFACE TROUGH/WARM FRONT. EXPECT PRECIP SUNDAY EVENING TO DEVELOP ALONG THAT SURFACE BOUNDARY IN NORTHEAST NEBRASKA THEN SPREAD/DEVELOP SOUTHEAST AND EAST AS BOUNDARY ROTATES EAST THEN NORTHEAST. STRONG WARM ADVECTION OVER SURFACE FRONT IS SHOWN BY ALL MODELS WITH 850 JET OVER 40KT RIDING ISENTROPES SOUTHWEST TO NORTHEAST ACROSS THE CWA. HIGHEST PRECIPITATION CHANCES WILL SHIFT TO THE EASTERN HALF OF THE CWA BY 12Z MONDAY...THEN GRADUALLY WORK EAST OF OUR AREA BY NOON. IT APPEARS PRECIPITATION TYPE WILL REMAIN ALL RAIN THROUGH THIS TIME AS SURFACE TEMPERATURES REMAIN ABOVE FREEZING UNTIL COLD ADVECTION KICKS IN AFTER PRECIP ENDS. FORECAST SOUNDINGS ALSO SHOW ABOVE-FREEZING AIR IN THE LOWEST 6000FT DURING PRECIPITATION. SHOULD SEE A PRECIPITATION-FREE PERIOD FOR A TIME MONDAY BEFORE UPPER LOW SWINGS ANOTHER SHORTWAVE INTO THE CWA LATER MONDAY AFTERNOON AND OVERNIGHT. BY THIS TIME TEMPERATURES WILL BE COLD ENOUGH FOR SNOW IN ALL AREAS. MOISTURE/LIFT WILL FAVOR NORTHEAST NEBRASKA FOR HIGHEST POTENTIAL FOR ACCUMULATING SNOW WITH CHANCES DIMINISHING TO NEAR ZERO AS WE HEAD TO THE KANSAS AND MISSOURI BORDERS. AVERAGE QPF FROM MODEL OUTPUT SUGGESTS AN INCH OR TWO OF SNOW IS POSSIBLE ALONG THE SOUTH DAKOTA BORDER DROPPING TO A HALF INCH OR LESS ALONG INTERSTATE 80. A FEW SNOW SHOWERS COULD LINGER INTO TUESDAY MORNING BEFORE SHORTWAVE ROTATES FAR ENOUGH EAST. CLEARING SKIES AND STRONG NORTHWEST WINDS WILL FOLLOW TUESDAY AFTERNOON. HAVE HIGHS THEN IN THE 30S WITH WINDS GUSTING OVER 30. .LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY) ISSUED AT 255 PM CST SAT DEC 20 2014 THE CHANCE FOR SNOW CHRISTMAS NIGHT INTO FRIDAY REMAINS THE PRIMARY LONGER TERM FORECAST CONCERN. UPPER TROUGH/LOW IN THE MIDDLE OF THE COUNTRY TUESDAY NIGHT WILL GRADUALLY WORK EAST ON WEDNESDAY...THEN SWING THROUGH NEW ENGLAND ON CHRISTMAS DAY. MEANWHILE ANOTHER TROUGH WILL BEGIN TO DEEPEN IN THE WESTERN STATES...AND WILL EVENTUALLY MOVE INTO THE PLAINS LATE IN THE WEEK. MODELS...AT LEAST THE 12Z VERSIONS OF THE OPERATIONAL GFS AND ECMWF...ARE IN BETTER AGREEMENT TODAY IN REGARDS TO STRENGTH AND TIMING OF TROUGH SHIFTING INTO THE REGION THURSDAY NIGHT AND LIFTING OUT ON SATURDAY. AHEAD OF IT...THE TRANSITION FROM NORTH OR NORTHWEST TO SOUTHWEST FLOW ALOFT WILL OCCUR WEDNESDAY INTO THURSDAY...WITH ASSOCIATED GRADUAL LOW LEVEL WARMING. SO TEMPERATURES MAY GAIN A FEW DEGREES BOTH WEDNESDAY AND THURSDAY...BUT INCREASING CLOUDS WILL CERTAINLY LIMIT AMOUNT OF WARMING. HAVE HIGHS IN THE 30S EACH DAY. EXPECT PRECIPITATION CHANCES TO INCREASE THURSDAY NIGHT AS ISENTROPIC UPGLIDE COMMENCES ON EAST AND NORTH SIDE OF SURFACE LOW EXPECTED TO TRACK ACROSS KANSAS INTO MISSOURI. TEMPERATURE PROFILES IN PRECIP AREAS SUGGEST AN ALL SNOW EVENT...AND FAVORING NORTHEAST NEBRASKA AT THIS TIME. PRECIP LOOKS TO MOVE OUT OF THE AREA BY FRIDAY NIGHT...WITH AMOUNTS GENERALLY LOOKING LIKE A FEW INCHES AT THE MAX. COOLER TEMPERATURES WILL FOLLOW WITH HIGHS FRIDAY AND SATURDAY NEAR 30.
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&& .AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1128 AM CST SAT DEC 20 2014 ONCE AGAIN EASTERN NEBRASKA AND WESTERN IOWA WILL BE UNDER DREARY GRAY BLANKET OF LOW CLOUDS AND MAYBE SOME LINGERING PATCHY LIGHT DRIZZLE. LIFR AND IFR CLOUD DECK EXTENDS FROM JUST EAST OF KONL TO JUST WEST OF KHSI AND KHJH. WEST OF THAT LINE SKIES ARE MOSTLY SUNNY WITH SOME MID AND HIGH CLOUDS AS YOU APPROACH THE WESTERN HIGH PLAINS. WITH LINGERING FRONTAL BOUNDARY ACROSS EASTERN NEBRASKA WITH CONTINUED LOW LEVEL SOUTHERLY MOIST FLOW...DO NOT EXPECT ANY BIG IMPROVEMENTS AT ANY OF THE THREE TAF SITES THROUGHOUT THIS FORECAST PERIOD. DID PUT IN BRIEF MVFR CEILINGS AROUND 22Z BUT NOT A LOT OF CONFIDENCE IN THAT FORECAST AND BY03Z OR 04 Z WOULD EXPECT IVF AND LIFR TO SETTLE IN AGAIN. DID NOT INCLUDE ANY MENTION -FZDZ AT THE THREE TAF SITES TONIGHT AS IT WILL BE VERY PATCHY IN NATURE IF THERE IS ANY AT ALL. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...DERGAN LONG TERM...DERGAN AVIATION...MEYER

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