Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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897 FXUS63 KOAX 081805 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 1205 PM CST MON FEB 8 2016 .UPDATE... ISSUED AT 1205 PM CST MON FEB 8 2016 SENT OUT A MINOR UPDATE AS HEADLINE FOR WINTER WEATHER ADVISORY IN EASTERN NEBRASKA EXPIRED...BUT CONTINUES IN IOWA. WIND ADVISORY REMAINS IN EFFECT THIS AFTERNOON. UPDATE ISSUED AT 940 AM CST MON FEB 8 2016 MADE SOME MINOR ADJUSTMENTS TO HEADLINES. EXTENDED WIND ADVISORY AN HOUR TO AGREE WITH NEIGHBORING OFFICE AND EXTENDED WINTER WEATHER ADVISORY FOR OUR IOWA COUNTIES UNTIL 6 PM. SNOW SHOWERS CONTINUE TO MOVE QUICKLY SOUTH/SOUTHEAST ACROSS THE AREA. COVERAGE OF PCPN AND VISIBILITIES FROM OBSERVATIONS AND WEB CAMS ARE WORSE IN IOWA THAN NEBRASKA. THAT IS THE REASON FOR THE DIFFERENCE IN EXPIRATION TIME. TEMPERATURES MAY WARM SLIGHTLY YET TODAY BUT WILL SLIDE OFF MID TO LATE AFTERNOON. READINGS UPSTREAM IN EASTERN SOUTH DAKOTA WERE IN THE UPPER TEENS AND LOWER 20S. FORECAST SOUNDINGS SHOW SOME LOW LEVEL MOISTURE AND POTENTIAL FOR FLURRIES INTO THE EVENING BEFORE CLOUDS DECREASE LATER TONIGHT. && .SHORT TERM...(TODAY THROUGH WEDNESDAY) ISSUED AT 345 AM CST MON FEB 8 2016 THE PRIMARY FORECAST CONCERN IS THE CONTINUATION OF STRONG WINDS AND AREAS OF BLOWING SNOW TODAY. 08/00Z 500-MB ANALYSIS SHOWED THE PRIMARY AREA OF HEIGHT FALLS LOCATED FROM THE MID-MO TO MID-MS VALLEYS IN ASSOCIATION WITH A RAPIDLY AMPLIFYING MID-LEVEL TROUGH OVER THE CNTRL PART OF THE NATION. A 90-95 KT JET STREAK OBSERVED AT 500 MB FROM THE OZARK PLATEAU INTO NRN HIGH PLAINS WILL PROGRESS INTO THE GULF COAST STATES...CONTRIBUTING TO THE DEVELOPMENT OF A MAJOR TROUGH ACROSS THE ERN HALF OF THE U.S. OVER THE NEXT 24-36 HOURS. WEAK MID-LEVEL PERTURBATIONS ON THE BACKSIDE OF THIS EVOLVING STORM SYSTEM IN CONJUNCTION WITH STEEP LOW-LEVEL LAPSE IN THE LOWEST 1-1.5 KM AGL HAVE CONTRIBUTED TO NW-SE-ORIENTED CONVECTIVE SNOW BANDS FROM SERN SD/SWRN MN INTO NWRN MO EARLY THIS MORNING. CONSENSUS OF LATEST CONVECTION-ALLOWING MODEL GUIDANCE IS SUGGESTIVE THAT THE BULK OF THE SNOW SHOWERS SHOULD SHIFT TO THE SOUTH OF THE AREA BY MID MORNING. NONETHELESS...THE RECENT DUSTING OF SNOW COUPLED WITH THE STRONG NW WINDS WILL CONTINUE REDUCE VISIBILITIES...SO WE WILL TEMPORALLY EXTEND THE CURRENT WINTER WEATHER ADVISORY UNTIL NOON. OTHERWISE...09Z METAR DATA ACROSS THE REGION INDICATE SUSTAINED WINDS OF 20 TO 25 MPH WITH GUSTS AS HIGH AS 40-45 MPH. WHILE THE SURFACE PRESSURE GRADIENT WILL GRADUALLY RELAX TODAY...THE ONSET OF DIURNAL MIXING OF THE BOUNDARY-LAYER WILL PROMOTE THE DOWNWARD TRANSFER OF HIGHER-MOMENTUM FLOW ALOFT. THE NET RESULT WILL BE ADVISORY-CRITERIA WIND SPEEDS CONTINUING TODAY AREAWIDE. AS SUCH...WE WILL TEMPORALLY EXTEND THE WIND ADVISORY IN EFFECT FOR NORTHEAST NEBRASKA FROM 18Z TO 23Z. SPEAKING OF MIXING...THIS PROCESS HAS KEPT TEMPERATURES IN THE UPPER 20S TO LOWER 30S EARLY THIS MORNING. AND WHILE WE MAY SOME DECREASE IN CLOUDS FROM W-TO-E ACROSS THE AREA TODAY...WEAK COLD ADVECTION IN THE LOW LEVELS WILL OFFSET ANY DIABATIC WARMING WITH ONLY A SMALL UPTICK IN TEMPERATURES ANTICIPATED THIS AFTERNOON. ONLY A SLIGHT EWD SHIFT OF THE LARGE-SCALE TROUGH IS FORECAST FROM TONIGHT THROUGH WEDNESDAY...AND AS MENTIONED ABOVE...THIS WILL RESULT IN GRADUALLY DECREASING WIND SPEEDS BEGINNING TONIGHT. WE WILL REMAIN ON THE WRN PERIPHERY OF A COLD CONTINENTAL AIR MASS PRESENT OVER MUCH OF THE ERN U.S INTO MID WEEK...SO HIGHS WILL REMAIN IN THE 20S AND 30S. THERE IS SOME INDICATION IN NAM AND GFS GUIDANCE THAT AN INCREASE IN LOWER TO MID-LEVEL FRONTOGENESIS COULD FOSTER A BAND OF LIGHT SNOW FROM CNTRL SD INTO N-CNTRL AND PERHAPS NERN NEB TUESDAY NIGHT INTO WEDNESDAY. THE ECMWF AND SHORT-RANGE ENSEMBLE GUIDANCE MAINTAIN A DRY FORECAST...WHICH IS THE WAY WE WILL LEAN AT THIS TIME. .LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY) ISSUED AT 345 AM CST MON FEB 8 2016 THE MEDIUM-RANGE MODELS ARE IN REASONABLY GOOD AGREEMENT THROUGH ABOUT FRIDAY WITH RESPECT TO THE LARGE-SCALE PATTERN. IN GENERAL...THESE DATA INDICATE THE GRADUAL EWD SHIFT AND DE- AMPLIFICATION OF THE ERN U.S. TROUGH THROUGH THURSDAY BEFORE THE TROUGH RE-INTENSIFIES FRIDAY INTO THIS WEEKEND OVER THE ERN THIRD OF THE NATION. WE WILL SEE A GRADUAL TRANSITION TO NWLY FLOW IN THE MID- LEVELS WITH A NUMBER OF WEAK PERTURBATIONS TRANSLATING SEWD THROUGH THIS FLOW REGIME. WHILE THE CHANCE FOR PRECIPITATION WILL NOT BE HIGH WITH THESE TRANSITORY SYSTEMS...THEY WILL AUGMENT THE LOCATION OF THE MEAN LOW-LEVEL BAROCLINIC ZONE. DETAILS IN THE TIMING OF THESE FEATURES VARY FROM MODEL-TO-MODEL...AND AS SUCH...CONFIDENCE IN OUR TEMPERATURE FORECASTS REMAINS RATHER LOW. SATURDAY AND SUNDAY...THERE ARE INDICATIONS THAT A SHORT-WAVE TROUGH WILL TEMPORARILY DAMPEN THE WRN U.S. RIDGE...PRIOR TO TRACKING INTO THE N-CNTRL U.S. THE DETERMINISTIC GFS IS SIMILAR TO THE GEFS MEAN IN SUGGESTING THAT THIS IMPULSE WILL BE RATHER LOW-AMPLITUDE IN CHARACTER. IN CONTRAST...THE ECMWF DEPICTS A MUCH MORE AMPLIFIED SOLUTION WHICH WOULD BRING A CHANCE OF PRECIPITATION TO THE AREA SUNDAY. CERTAINTY IN EITHER SOLUTION REMAINS LOW AT THIS TIME. && .AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1205 PM CST MON FEB 8 2016 SOME MVFR CEILING SHOULD LINGER THIS AFTERNOON WITH OCCASIONAL LIGHT SNOW SHOWERS...ESPECIALLY AT KOMA. THE MAJORITY OF THE SHORT RANGE MODEL GUIDANCE TENDS TO DECREASE CLOUDS BELOW 5000 FEET LATE THIS AFTERNOON OR EARLY EVENING...WITH VARIABLE MID AND HIGH CLOUDS AFTER THAT. THERE IS SOME GUIDANCE THAT DOES KEEP MVFR CEILINGS WELL INTO THE EVENING...SO THAT IS POSSIBLE. EXPECT A GRADUAL DECREASE IN WINDS LATE THIS AFTERNOON AND EVENING... WITH GUSTS ENDING OVERNIGHT. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR NEZ011-012-015>018- 030>034-042>045-050>053-065>068-078-088>093. IA...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR IAZ043- 055-056-069-079-080-090-091. WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR IAZ043-055-056-069- 079-080-090-091. && $$ UPDATE...MILLER SHORT TERM...MEAD LONG TERM...MEAD AVIATION...MILLER

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