FXUS63 KOAX 241604
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1104 AM CDT WED AUG 24 2011
.UPDATE...
MINOR EDITS FOR HOURLY TRENDS.
&&
.DISCUSSION...
SURFACE HIGH PRESSURE CONTINUES TO BUILD SOUTH INTO THE CENTRAL
PLAINS RESULTING IN FALLING SFC DEW POINT TEMPS AND 10-15KTS
NORTHERLY WINDS. ONLY MINOR EDITS WERE NEEDED FOR THIS MORNINGS
UPDATE...MAINLY REGARDING HOURLY TRENDS OF TEMPERATURES AND WIND
BASED ON LATEST OBS AND NEAR TERM GUIDANCE.
&&
.PREV DISCUSSION... /ISSUED 354 AM CDT WED AUG 24 2011/
DISCUSSION...
MASSIVE UPPER LEVEL RIDGE WILL REMAIN IN PLACE ACROSS THE SW
CONUS...SUPPORTING MEAN NW FLOW OVER MUCH OF THE NORTHERN TIER
THROUGH THE PERIOD. DISTURBED NW FLOW WILL CONTINUE TO SUPPORT
PERIODIC IMPULSES INTO THE CENTRAL PLAINS...WITH INCREASED CHANCES
FOR PRECIP WITH EACH DISTURBANCE...THE FIRST OF SUCH DISTURBANCE
WILL ARRIVE LATE THUR NIGHT...WITH ANOTHER SYSTEM EXPECTED LATE SAT
INTO SUNDAY. INCREASINGLY COMPLICATED FLOW REGIME OVER THE NE PAC PER
TROUGH MERGER/PHASING PROCESSES WILL SUPPORT GROWING UNCERTAINTY IN MID
LEVEL SHORTWAVE PHASE SPEED/TROUGH DEPTH WITH TRACK LOCATION HINGING
ON THE DEGREE OF HEIGHT FALLS INTO THE GREAT LAKES AND UPPER MIDWEST
BY DAY 3-4. HENCE...NO BIG CHANGES BEYOND DAY 5 UNTIL UPSTREAM
FLOW/TROUGH FEATURES ARE BETTER ASSIMILATED INTO FORECAST MODELS. NO
STRONG PREFERENCE IN MODEL SOLUTIONS GIVEN GENERAL AGREEMENT IN
SYNOPTIC EVOLUTION THROUGH THE PERIOD...ALTHOUGH DID FAVOR THE GFS
IN THE SHORT TERM GIVEN PREFERENCE TOWARD THERMAL FIELD HANDLING AND
ELEVATED CONVECTION EVOLUTION.
TODAY THROUGH THURSDAY...LL TROUGH FEATURE WILL CONTINUE TO SHIFT
SOUTH OF THE FA TODAY...WITH THE ASSOCIATED THETA-E RIDGE FOLLOWING
SUITE. MORNING FOG WILL QUICKLY DISSIPATE AS FLOW INCREASES AND MIXING
ENSUES. WEAK NEGATIVE THETA-E ADV COUPLED WITH DIURNAL MIXING WILL
SUPPORT GRADUAL DEWPOINT FALLS THIS AFTERNOON. MOSTLY SUNNY SKIES
CAN BE EXPECTED THROUGH THUR...ALTHOUGH AN INCREASE IN MID AND HIGH
CLOUDS ARE POSSIBLE BY THUR GIVEN VEERING LL FLOW SUPPORTING POS
THETA-E ADV OVER THE HIGH PLAINS. COOL CONDITIONS CAN BE EXPECTED
TONIGHT GIVEN DRIER AIR RETURNING TO THE REGION WITH LOWS IN THE
UPPER 50S AND LOWER 60S. PATCHY FOG WILL BE POSSIBLE ONCE AGAIN
TONIGHT GIVEN LIGHT FLOW AND EXCELLENT RADIATIONAL COOLING SETUP. SE
FLOW WILL RETURN TO THE AREA ON THRU...WITH VEERING FLOW ALOFT
SUPPORTING POSITIVE THETA-E ADV AT THE BASE OF A GROWING EML.
INCREASING NOCTURNAL LLJ THUR NIGHT WITH THE PRESENCE OF A
SUBSTANTIAL EML WILL SUPPORT ELEVATED THUNDER CHANCES GIVEN
INCREASING ELEVATED INSTABILITY. RETAINED LOW POP MENTION OVER MOST
OF THE AREA...INCREASING TO CHANCE WORDING NORTHERN ZONES GIVEN THE
LOCATION OF THE LLJ NOSE AND STRONGEST LL MOISTURE TRANSPORT.
FRIDAY THROUGH SAT...SFC TROUGH AND ASSOCIATED UPPER IMPULSE WILL
SUPPORT INCREASING CHANCES FOR THUNDER ON FRIDAY...WITH THE BEST
CHANCES FOR CONVECTION POTENTIALLY BEING ELEVATED IN NATURE GIVEN
THE DEGREE OF SB CIN IN PLACE PER THE EML. RETAINED ONLY LOW POPS
ATTM. INCREASED LL HUMIDITY CAN BE EXPECTED WITH HIGHS HINGING ON
THE DEGREE OF CLOUD COVER AND POTENTIAL RESIDUAL ELEVATED CONVECTION
PER POS THETA-E ADV. OPTED FOR DRY CONDITIONS ON SAT GIVEN WEAK SFC
RIDGING AND LOSS OF DEEP MOISTURE WHICH WILL SHIFT SOUTH AND WEST OF
THE REGION.
SUN-TUE...FORECAST MODELS AND MEAN ENSEMBLES CONTINUE TO INDICATE A
STRONG UPPER TROUGH ADVECTION THROUGH THE REGION ON SUNDAY...WITH
WAA/POSITIVE THETA-E ADV PROCESS FOLLOWED BY A LL SFC TROUGH
PASSAGE. RETAINED POPS SUN/SUN NIGHT. SIG HEIGHT FALLS INTO THE
REGION REMAIN ON TRACK EARLY NEXT WEEK WITH MUCH COOLER WEATHER
EXPECTED. TRENDED TEMPS DOWN A FEW DEGREES WITH DRY CONDITIONS
FORECAST GIVEN LACK OF SIG FORCING WITH A REMOVAL OF DEEP MOISTURE
FROM THE REGION. JC
AVIATION...
FOR THE 06Z TAFS...
WEAK COLD FRONT WITH LIGHT WEST/NORTHWEST WINDS HAS CLEARED KOFK AND
SHOULD EXIT KOMA AND KLNK BY AROUND 12Z. DUE TO HIGH SURFACE
DEWPOINTS...THE POTENTIAL FOR FOG REMAINS FOR TAF SITES. KOMA AND
KLNK ARE EXPECTED TO FALL TO MVFR VSBYS IN THE NEXT FEW HOURS WHILE
KOFK SHOULD REMAIN IN MVFR THROUGH 12Z. IFR OR LOWER VSBYS ARE NOT
EXPECTED BUT WILL CLOSELY MONITOR.
ANY LINGERING FOG TO QUICKLY LIFT AFTER SUNRISE WITH VFR CONDITIONS
TO PREVAIL FOR REMAINDER OF TAF CYCLE.
KAR
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
NH