891 
FXUS63 KOAX 060410
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1110 PM CDT FRI APR 5 2013

.AVIATION...06Z TAFS FOR KOFK...KLNK AND KOMA.

VFR CONDITIONS ARE EXPECTED THROUGH SATURDAY EVENING. SOUTH WINDS
15 TO 25KT WILL TURN NORTHWEST AND INCREASE INTO 15 TO 30KT RANGE
BETWEEN 12Z AND 15Z AT ALL TAF SITES. THOSE WINDS SHOULD DIMINISH
TO NEAR 12KT AT 00Z. ONLY MID LEVEL CIGS AT OR ABOVE FL120 ARE
FORECAST.

DERGAN

&&

.PREV DISCUSSION... /ISSUED 339 PM CDT FRI APR 5 2013/

DISCUSSION...

EARLY AFTERNOON WATER VAPOR IMAGERY INDICATED A STRONG UPPER
LEVEL SHORTWAVE TROUGH MOVING THROUGH ID/WRN MT. THIS WAS
ASSOCIATED WITH 60-70 M H5 HEIGHT FALLS ON THE 12Z UPPER AIR
ANALYSIS AND A 75 KT H3 JET SEGMENT. THE SYSTEM IS EXPECTED TO
TRACK EAST TONIGHT ACROSS THE NORTHERN PLAINS...AND EAST OF THE
AREA ON SATURDAY. THE STRONGEST Q-G FORCING ASSOCIATED WITH THE
SYSTEM WILL MISS THE FA TO THE NORTH...AND THIS ALONG WITH
EXTREMELY LIMITED MOISTURE WILL RESULT IN VERY LITTLE CHANCE OF
MEASURABLE PRECIP FOR THE CWA. THUS HAVE REMOVED POPS IN ALL AREAS
BUT THE FAR NORTH WITH MAYBE SOME SPRINKLES FARTHER SOUTH AND
EAST. A COLD FRONT WILL MOVE THROUGH THE CWA SATURDAY MORNING
WITH WINDS TURNING GUSTY FROM THE NORTHWEST. THE CAA WILL BE
OFFSET BY THE DEGREE OF MIXING EXPECTED ON SAT WITH DRY CONDITIONS
AND A GOOD DEAL OF SUNSHINE WITH HIGHS ONCE AGAIN GETTING INTO THE
MID 60S NORTH TO LOWER 70S SOUTH. GIVEN THE VERY DRY
CONDITIONS...WARM TEMPERATURES AND STRONG WINDS...FIRE WEATHER
WILL BE A COCERN FOR SAT AS WELL. 

QUIET WEATHER IS EXPECTED TO CONTINUE SAT NIGHT AND FOR A GOOD
PART OF THE DAY ON SUNDAY BEFORE THE NEXT SHORTWAVE TROUGH WILL
EJECT INTO THE PLAINS. MODELS ARE HAVING SOME TROUBLE WITH THE
LATITUDE OF THE STRONGEST UPPER LEVEL FORCING...BUT THERE IS
GENERALLY AGREEMENT THAT ISENTROPIC LIFT WILL INCREASE THROUGH THE
DAY ON SUNDAY AHEAD OF THIS SYSTEM...AND COMBINE WITH SOME
MOISTURE TURN TO PRODUCE SOME SHOWERS BY AFTERNOON. ALTHOUGH
INCREASING CLOUDS WILL LIMIT HIGH TEMPERATURES...MIXING TO NEAR
850 MB SHOULD YIELD HIGHS IN THE MID AND UPPER 60S. WAA WILL
INCREASE ON SUNDAY NIGHT AS THE NOCTURNAL LOW-LEVEL JET DEVELOPS
ACROSS THE SOUTHERN PLAINS. BEST COMBINATION OF ASCENT DUE TO
TEMPERATURE/MOISTURE ADVECTION WILL BE IN THE SOUTHERN AND ERN CWA
WHERE WE HAVE MID TO HIGH CHANCE POPS. ENVIRONMENTAL LAPSE RATES
OF 7 TO 7.5 COMBINED WITH THE MOISTURE ALSO INDICATES SOME THUNDER
POTENTIAL AS WELL. 

THE VARIABILITY IN THE MODELS ONLY INCREASES INTO EARLY NEXT WEEK
AS SIGNIFICANT HEIGHT FALLS MOVE INTO THE GREAT BASIN OF THE WRN
US. HOW THIS UPPER LEVEL SYSTEM EVOLVES AND MOVES ACROSS THE WRN
AND CENTRAL US THROUGH WED IS VERY UNCERTAIN ATTM...AND THUS WE WILL
MAKE VERY FEW CHANGES TO THE GOING FORECAST. A COMPOSITE OF ALL
THE GLOBAL MODELS AND THEIR RESPECTIVE ENSEMBLES INDICATES THE
BEST CHANCE OF PRECIPITATION WILL BE FROM MONDAY NIGHT THROUGH
TUES NIGHT AND THIS IS WHEN WE WILL PLACE THE HIGHEST POPS.
VARIOUS RUNS OF VARIOUS MODELS INDICATE THAT THERE IS SOME
POTENTIAL FOR THE WARM SECTOR TO GET CLOSE ENOUGH TO OUR SOUTHERN
CWA ON MON/TUE TO DEAL WITH A THUNDERSTORM THREAT...WHILE OTHER
MODELS KEEP THIS AIR FARTHER SOUTH INTO KS...WHICH WE CURRENTLY
FEEL IS THE MORE LIKELY SOLUTION. GIVEN THE COLDER SOLUTIONS OF
VARIOUS MODELS THERE IS ALSO SOME SNOW POTENTIAL IN OUR NW CWA FOR
THE TUE NIGHT/WED PERIOD...BUT AGAIN OTHER MODELS ARE LESS
AGGRESSIVE WITH THE COLD AIR. THE LONG RANGES GENERALLY AGREE
THOUGH THAT ANY EFFECTS OF THIS SYSTEM WILL BE OUT OF THE ARE BY
THU AND WILL HAVE A DRY END TO THE EXTENDED WITH MODERATING
TEMPERATURES.

BOUSTEAD

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&

$$