Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000 FXUS63 KOAX 191742 AFDOAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 1242 PM CDT FRI SEP 19 2014 .UPDATE... ISSUED AT 1230 PM CDT FRI SEP 19 2014 MAKE SOME TWEAKS WITH MORNING UPDATES MAINLY FOR THE VARIABLE LOW CLOUDS AND HOURLY TEMPERATURES. THE STRATUS IS MOVING OUT WITH THE WARM FRONT AND TEMPERATURES ARE WARMING INTO THE 80S WITH SOUTHWEST WINDS 15 TO 30 MPH. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 320 AM CDT FRI SEP 19 2014 ...CONVECTIVE CHANCES TONIGHT ARE THE MAIN FORECAST CONCERN IN THE SHORT TERM... EARLY MORNING WATER VAPOR IMAGERY INDICATED A POSITIVELY TILTED UPPER LEVEL TROUGH EXTENDING FROM SASK SOUTHWEST TO NV. THIS TROUGH WILL MOVE INTO THE NORTHERN PLAINS TODAY AND ALLOW FOR THE COLD FRONT /CURRENTLY EXTNDG FROM CNTRL ND INTO WRN SD/ TO ADVANCE TO NEAR THE SD/NEB BORDER BY LATE THIS AFTERNOON. AHEAD OF THE FRONT WE WILL SEE THE LOW CLOUDS/FOG EXIT TO THE E BY MID MORNING WITH A GOOD DEAL OF SUN AND DRY WEATHER EXPECTED TODAY. TEMPERATURES AT 850 MB ARE PRETTY WARM FOR THIS TIME OF YEAR...AND WITH DEEP MIXING JUST AHEAD OF THE FRONT WE MAY SEE SOME PRETTY HOT TEMPERATURES WITHIN THE 850 MB THERMAL AXIS ACROSS NORTHERN NEB. WE HAVE INCREASE HIGHS INTO THE LOWER TO MID 90S FOR PARTS OF THE EXTREME NORTHWEST CWA...BUT MOST LOCATIONS WILL SEE MID TO UPPER 80S OVER ERN NEB AND LOWER TO MID 80S OVER WRN IA. THE 00Z UPPER AIR ANALYSIS INDCD SEASONABLY RICH MOISTURE HAD ADVECTED NORTH THROUGH THE PLAINS WITH MIXING RATIOS OF +10 G/KG AT LEAST TO KTOP. AS THE TROUGH NEARS TODAY AND THE MID AND UPPER LEVEL FLOW INCREASES FROM THE WEST WE SHOULD SEE A WELL-DEVELOPED EML OVERSPREAD THIS MOISTURE AND LEAD TO A MODERATELY UNSTABLE ATMOSPHERE OVER THE CWA BY LATE AFTN WITH MLCAPE VALUES OF 2000-3000 J/KG. THE LACK OF LARGE-SCALE HEIGHT FALLS OR ANY DVPA...AS WELL AS THE STRONG EML...WILL KEEP THE FA CAPPED THROUGH THE DAY TODAY. MODELS DO INDICATE THIS WILL LIKELY CHANGE THIS EVENING THOUGH AS HEIGHT FALLS MOV INTO ERN NEB/SD ALLOWING FOR A WEAKENING OF THE EML AND THIS...ALONG WITH THE INCOMING FRONT...WILL LIKELY ALLOW FOR CI. CURRENT THINKING IS THAT THIS WILL BE JUST BEHIND THE SFC BOUNDARY IN THE 01-03Z TIME FRAME FROM AROUND NELIGH TO WAYNE AREA. STORMS WILL LIKELY INCREASE IN COVERAGE AS THEY WORK SOUTHEAST OVERNIGHT WITH REMNANT OF ANY WEAK MCS REACHING THE IA/MO BORDER AROUND 12Z SAT. WIDESPREAD SEVERE WEATHER IS NOT EXPECTED DUE TO SLIGHTLY ELEVATED NATURE OF THE CONVECTION THIS EVENING...BUT GIVEN THE INSTABILITY AND 25 TO 30 KT OF EFFECTIVE SHEAR WE COULD SEE A STORM OR TWO APPROACH SEVERE LIMITS WITH HAIL BEING THE MAIN THREAT FOR AN HOUR OR TWO AFTER INITIATION. THE FRONT WILL STILL BE MOVING THROUGH THE SOUTHERN CWA DURING THE DAY ON SAT...BUT IT APPEARS THAT MOST OF REDEVELOPMENT OF CONVECTION LATE SAT AFTERNOON WILL BE ACROSS ERN KS/MO. WITH THE SLOWER MOVEMENT OF THE FRONT WE DID INCREASE HIGHS A TOUCH SAT AFTERNOON INTO THE SOUTHERN CWA. THE REST OF THE SHORT-TERM FORECAST LOOKS FAIRLY QUIET WITH HIGH PRESSURE DEVELOPING THROUGH THE CWA ON SAT NIGHT/SUN WITH HIGHS/LOWS RETURNING TO NEAR NORMAL. .LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY) ISSUED AT 320 AM CDT FRI SEP 19 2014 THE QUIET WEATHER THAT ENDS THE SHORT TERM PERIOD OF THE FORECAST WILL CONTINUE INTO THE MON TIME FRAME OF THE EXTENDED PERIOD. AFTER THAT GLOBAL MODELS INDICATE A TROUGH MOVING THROUGH THE CNTRL PLAINS. THIS LOOKS TO BRING ANOTHER CHANCE OF SOME SHOWERS TO THE REGION MAINLY ON TUE. THE CONFIDENCE ON THIS TROUGH IS LIMITED THOUGH AS THE SYSTEM WILL GENERALLY BE CUT-OFF FROM THE MAIN WESTERLIES THAT WILL BE RETREATING NWD INTO CANADA THROUGH THE WEEK. THUS THE CONFIDENCE IN THE TIMING OF PRECIP AND COVERAGE IS LIMITED AND WE WILL KEEP POPS IN THE CHC CATEGORY FOR NOW. OTHERWISE WITH SOME CLOUDS AND POSSIBLE PRECIP TEMPS SHOULD GENERALLY BE BACK INTO THE 70S FOR HIGHS AND 50S FOR LOWS. && .AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1230 PM CDT FRI SEP 19 2014 A COLD FRONT WILL MOVE INTO THE REGION TONIGHT...WITH SCATTERED SHOWERS AND THUNDERSTORMS. AHEAD OF THE FRONT...LOOK FOR VFR CONDITIONS AND SURFACE WINDS FROM THE SOUTH AND SOUTHWEST AT 15 TO 20KTS SUSTAINED AND GUSTS 25 TO 30KTS. ISOLATED SHRA/TSRA MAY BE NEAR KOFK BY 02-04Z...AND INCLUDED A PROB30 FOR TSRA AT THE TAF SITES FOR A COUPLE OF HOURS WITH THE FRONT. THE FRONT DOES SLOW DOWN...HOWEVER THE FORCING WEAKENS...SO DO NOT HAVE A MENTION AFTER 11Z AT KLNK/KOMA. COVERAGE AND TIMING WILL LIKELY NEED ADJUSTING DEPENDING ON HOW IT EVOLVES. THE SURFACE WINDS LIGHTEN AS THE WIND SHIFT APPROACHES THEN EVENTUALLY TURNS TO THE NW 6-12KTS. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ UPDATE...ZAPOTOCNY SHORT TERM...BOUSTEAD LONG TERM...BOUSTEAD AVIATION...ZAPOTOCNY

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