FXUS63 KOAX 021957
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
257 PM CDT SAT JUL 2 2011
.DISCUSSION...
TONIGHT AND SUNDAY...SEVERAL DISTURBANCES ALOFT WILL LIKELY BRING
INCREASING THUNDERSTORM COVERAGE ACROSS THE FORECAST AREA INTO
SUNDAY. LEAD WAVE WAS MUCH MORE APPARENT ON WATER VAPOR IMAGERY
THAN 12Z SUBJECTIVE UPPER AIR ANALYSIS...ALTHOUGH A +6 DEG C H7
DEW POINT WAS NOTED AT BOU...WITH WAVE MOVING ACROSS SWRN
NEBRASKA EARLY IN THE AFTERNOON. QPF FROM MODELS DIFFER IN HOW IT
WILL EVOLVE THIS EVENING WITH GFS MORE AGGRESSIVE IN SPREADING IT
ACROSS MO RIVER BY LATE EVENING. SOME WEAK ACTIVITY WELL AHEAD OF
SYSTEM WAS APPROACHING WRN ZONES AS OF 1930Z...BUT MOST OF IT
REMAIN CONFINED CLOSER TO MAIN DISTURBANCE AT 19Z. THUS DID NOT
COMPLETELY BUY GFS AT THIS TIME. HOWEVER...DID INCREASE POPS
MARKEDLY WRN ZONES THIS EVENING AND SPREAD SOME SMALL POPS IN THE
LATE EVENING E OF MO RIVER AS DECENT ISENTROPIC UPGLIDE/WARM
ADVECTION SHOULD CONTINUE SPREADING OVER ERN NEBRASKA THROUGH
LATE EVENING/EARLY TONIGHT. OTHER SHORTWAVE ENERGY IS FORECAST TO
DROP IN BEHIND THIS SYSTEM ON SUNDAY AND STLT DOES APPEAR TO SHOW
SEVERAL SUBTLE WAVES FM NEBR PANHANDLE INTO WY/MT. SO WITH WEAK
H85 BOUNDARY ATTEMPTING TO LIFT BACK NORTH ON SUNDAY AS UPPER
RIDGE BUILDS TO OUR WEST...WIDESPREAD SHOWERS/TSTMS COULD LINGER
INTO MIDDAY SUNDAY AND POSSIBLY STRENGTHEN IF SOME HEATING CAN
DEVELOP. SO PRECIP CHANCES WERE ALSO INCREASED ON SUNDAY AND
TEMPERATURES WERE LOWERED A BIT PER WHAT WAS OCCURRING IN PARTS
OF SW/CNTRL NEBR TODAY. TRENDS WILL STILL HAVE TO BE WATCHED
HOWEVER AS 4KM WRF WEAKENS OVERNIGHT ACTIVITY BEFORE DEVELOPING
NEW CONVECTION IN THE AFTN ALONG APPARENT MCV IN WRN IA KEEPING
BETTER PCPN CHCS IN WRN IA AND THEN MAINLY IN AFTN. PRECIPITABLE
WATER VALUES FORECAST TO BE AROUND 2 INCHES IN SRN ZONES LATE
TNGT/SUNDAY...SO LOCALLY HEAVY RAIN POSSIBLE. NO FLASH FLOOD WATCH
WAS ISSUED WITH AFTERNOON PACKAGE AS CONVECTIVE DEBRIS ON SUNDAY
COULD LIMIT INSTABILITY IN MANY AREAS AND DID NOT FEEL PATTERN
WARRANTED A BLANKET FLASH FLOOD WATCH.
GENERALLY WARMING AND DRYING CONDITIONS EXPECTED MONDAY AS UPPER
RIDGE SHIFTS EWD A BIT. ALTHOUGH GFS DEVELOPED LIGHT QPF AMOUNTS
ACROSS AREA ON MONDAY...NOT ENOUGH UPPER SUPPORT WAS FOUND TO
INSERT POPS WITH THIS FORECAST.
AFTER THAT A WEAK WAVE RIDING OVER UPPER RIDGE WILL SEND A FRONT
THROUGH FORECAST AREA TUESDAY WITH 12Z GFS/00Z ECMWF DIVERGING ON
HOW MUCH POST FRONTAL PRECIP WILL OCCUR ON WEDNESDAY AND THEN HOW
MUCH PRECIP WILL OCCUR AS RETURN FLOW SETS UP AS FRONT
WEAKENS/WASHES OUT/LIFTS NWD. GFS AND GFS ENSEMBLE MEAN WERE GENERALLY
MORE BULLISH WITH PRECIP THAN THE ECMWF WHICH SHOVED DRIER AIR
FASTER AND FARTHER SWD SUGGESTING A DRIER FORECAST. SOME
COMPROMISE WAS USED BASED ON SURROUNDING OFFICES AND PREVIOUS
FORECAST...WITH HIGHEST POPS GENERALLY IN TUESDAY/TUESDAY NIGHT PDS.
TEMPERATURES TO COOL SOME MID WEEK/THURSDAY BEFORE REBOUNDING
AGAIN AHEAD OF NEXT FRONT FRIDAY/SATURDAY.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
VFR CONDITIONS EXPECTED THRU FIRST HALF OF THE TAF PD. HIGH CLOUDS
CONT TO MOVE OVERHEAD FROM ONGOING THUNDERSTORM ACTIVITY ACROSS
WESTERN AND CENTRAL NEBRASKA. LIGHT NORTHEAST WINDS WILL BECOME
SOUTHEAST THIS EVENING AS A HIGH PRESSURE AREA CONTINUES TO PUSH
EAST OF THE REGION. THIS WILL ALSO ALLOW SHOWERS AND THUNDERSTORMS
TO SPREAD WEST TO EAST OVER THE TAF SITES AFTER 06Z. HAVE INCLUDED
PROB30 GROUPS ALL THE WAY THRU 18Z AS TSTMS CHANCES CONTINUE THRU
SUNDAY MORNING.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
CHERMOK/KERN