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000
FXUS63 KOAX 242335
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
635 PM CDT FRI MAY 24 2013

.AVIATION...

00Z TAFS FOR KOMA...KLNK AND KOFK.

WILL WATCH PCPN CURRENTLY WEST OF KLNK...BUT DID NOT INCLUDE THIS
IN CURRENT TAF. WILL AMEND IF NEEDED. OTHERWISE...FAIRLY LOW
CONFIDENCE FORECAST ON TIMING OF TSRA. OVERALL...EXPECT CONDITIONS
TO DETERIORATE OVERNIGHT AS LOW LEVEL MOISTURE INCREASES. ALL THREE
SITES SHOULD DROP TO MVFR AND POSSIBLY TO IFR. LOOKING AT THE
LATEST 13KM RAP MODEL...EXPECT ACTIVITY CURRENTLY IN SOUTHWEST
NEBRASKA TO TRACK AND DEVELOP NORTHEAST TOWARD KOFK BY 08Z OR
09Z. CHANCES SEEM LOWER AT KLNK AND KOMA UNTIL LATE TONIGHT. THERE
WILL BE SOME CHANCE OF TSRA AT ALL THREE SITES 18Z-00Z TOMORROW
BUT CONFIDENCE WAS TOO LOW TO INCLUDE IN TAFS AT THIS TIME.

MILLER

&&

.PREV DISCUSSION... /ISSUED 252 PM CDT FRI MAY 24 2013/

DISCUSSION...

TIMING OF BEST PRECIPITATION CHANCES THROUGH MEMORIAL DAY WEEKEND
AND BEYOND MAIN CHALLENGE AND CONFIDENCE OF SKILL BEYOND
CLIMATOLOGY...I.E. HIGHEST POPS AT NIGHT...NOT THE HIGHEST.

18Z SURFACE + 12Z UPPER AIR ANALYSIS HAD SURFACE TO 850 MOIST
AXIS AND SUBJECTIVELY PLACED WARM FRONT FM SCNTRL KS INTO SWRN
NEBR. ALTHOUGH A FEW HIGH BASED SHOWERS DEVELOPING NE OF BOUNDARY
IN SCNTRL NEBR AND OTHER POSSIBLE HIGHER BASED ACTIVITY ACROSS
NRN/NERN ZONES EARLY WILL HAVE TO BE MONITORED...MAIN ACTION OVER
THE FORECAST AREA WILL PROBABLY BE FROM LATE THIS EVENING THROUGH
OVERNIGHT HOURS. ANY CONVECTION THAT INCREASES THROUGH THIS
EVENING WRN HIGH PLAINS WILL BE AIDED BY DECENT THETA ADVECTION
INTO BOUNDARY AS LOW LEVEL JET STRENGTHENS. 12Z GFS WAS PROBABLY
SUFFERING FEEDBACK ISSUES BY 12Z SAT IN SRN PLACEMENT OF MCS.
HOWEVER...SOME SRN EXTENSION OF AN MCS COULD MAKE IT INTO FAR
SWRN ZONES EARLY TONIGHT THUS LIKELY POPS ALL OF WRN ZONES JUST
AFT 06Z WITH ANY ACTIVITY THEN FOCUSING MORE ACROSS NERN ZONES SAT
MORNING BEFORE EXPECTED DECLINE.

AFTER TONIGHT DEEPER MOISTURE WILL OVERSPREAD MUCH OF THE
FORECAST AREA WITH MUCH HIGHER THAN NORMAL PRECIPITABLE WATER
VALUES GENERALLY LOCKED IN TILL MUCH OF THE ENERGY FROM WRN U.S.
TROUGH EJECTS LATE NEXT WEEK. WITH MOISTURE/INSTABILITY IN PLACE
AND SOME SORT OF WARM FRONT OR CONVECTIVELY ENHANCED BOUNDARY
POSSIBLY REMAINING OVER OR NEAR AREA...STRENGTHENING NOCTURNAL LOW
LEVEL JET PLUS ANY DISTURBANCES LIFTING OUT OF WRN TROUGH COULD
KEEP ACTIVE PATTERN IN PLACE...ESPECIALLY THROUGH HOLIDAY WEEKEND
AND THEN AGAIN BY NEXT THURSDAY. ALTHOUGH DID TRY TO DIURNALLY
DECREASE CHCS FROM SW TO NE ACROSS AREA ON SATURDAY...AFTER THAT
MADE LITTLE CHANGES TO POPS THROUGH MONDAY...WITH LIKELY POPS
GENERALLY RESERVED FOR NIGHTTIME WITH DECREASED DAYTIME POPS IN
TUE/WED PERIOD.

OVERNIGHT/EARLY SATURDAY CONVECTION COULD REINFORCE BOUNDARY
ACROSS FORECAST AREA SATURDAY...THUS KEPT TEMPS CLOSER TO A 00Z
ECMWF/12Z NAM COMPROMISE NRN AREAS WITH ANY 80+ MENTION CONFINED
TO SOUTHERN ZONES. AFTER MOISTURE BECOMES MORE UNIFORM OVER THE
AREA BEYOND SATURDAY...BETTER SFC THERMAL GRADIENT MAY SHIFT NE
OF AREA THUS PROVIDING MORE UNIFORM TEMPS ALTHOUGH 00Z ECMWF KEPT
SOME BOUNDARY/SLIGHTLY COOLER TEMPS OVER AREA THROUGH MONDAY.

CHERMOK

&&

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

$$