FXUS63 KOAX 181940
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
240 PM CDT MON APR 18 2011
.SHORT TERM...TONIGHT.
WITH ENE LOW LEVEL FLOW CLOUDS SHOULD FILL BACK ACROSS AREAS THAT
MANAGED TO IMPROVE THIS AFTERNOON. OTHERWISE FRONTOGENETICAL
FORCING/ISENTROPIC UPGLIDE SPREADS FROM WRN NEBRASKA ACROSS NERN
NEBRASKA EARLY TONIGHT FOLLOWED BY SLIGHTLY ELEVATED UNSTABLE AIR
MOVG TOWARD SERN NEBRASKA/SWRN IA LATER TONIGHT. SO WOULD INITIALLY
LOOK FOR RAIN AREA IN WRN NEBRASKA SPREADING MOSTLY ACROSS CNTRL/NRN
ZONES THROUGH 06Z WITH SHOWERS/CONVECTION DEVELOPING THEN SPREADING
INTO SERN ZONES AFT 06Z BUT WITH A GENERAL LOWER PROBABILITY THAN
FAR NRN ZONES. HOWEVER...RAISED MOST POPS AS GOOD AGREEMENT BETWEEN
MODELS AND BASED ON CURRENT TRENDS. BOTH NAM/GFS SUGGEST SOME
CHANGE OR MIX TO SNOW POSSIBLE FAR NWRN ZONES AND SINCE SOME PCPN
HAD CHANGED TO SNOW ACROSS SAND HILLS MENTIONED A MIX FAR NW AFT
06Z. DROPPED NW LOWS A FEW DEGREES OTHERWISE NO CHANGES MADE TO
LOWS TONIGHT.
CHERMOK
.LONG TERM...TUESDAY THROUGH MONDAY.
A WET AND COOL PATTERN LOOKS TO CONTINUE THROUGH THE FORECAST PERIOD.
LITTLE CHANGE TO OVERALL TRENDS WITH PRECIP TIMING AND TEMPERATURES
BEING THE PRIMARY CONCERNS.
MODELS HAVE INCREASED SPEED OF SYSTEM COMING ACROSS ON TUESDAY
WITH BOTH GFS AND NAM HAVING MAIN AREA OF PRECIP EAST OF THE CWA
AT THAT TIME. ALTHOUGH SHOWERS ARE LIKELYDURING THE DAY...AMOUNTS
SHOULD BE ON THE LIGHT SIDE IN MOST AREAS. STILL SOME CHANCE FOR A
LITTLE SNOW AT TIMES IN THE NORTH BUT NO ACCUMULATION EXPECTED.
THINGS DRY OUT TUESDAY NIGHT AND EXTEND THROUGH WEDNESDAY AS HIGH
PRESSURE BUILDS INTO THE AREA THEN MOVES EAST. NEXT ROUND OF RAIN
MOVES IN WEDNESDAY NIGHT THROUGH THURSDAY NIGHT AS WARM ADVECTION
PATTERN DEVELOPS AHEAD OF THE WESTERN TROUGH WITH SOME SUPPORT
FROM WEAK IMPULSES IN THE FLOW. MAIN UPPER WAVE THEN MAKES IT
THROUGH FRIDAY AND FRIDAY NIGHT CONTINUING A CHANCE OF SHOWERS.
REMAINDER OF THE EXTENDED PERIOD REMAINS UNCERTAIN AS GFS AND
ECMWF CONTINUE SHOWING DIFFERENT SOLUTIONS WITH ECMWF DEEPER AND
FURTHER WEST WITH THE UPPER TROUGH OVER THE WEST DAY 6 AND 7.
FOBERT
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
SOME LIFTING OF CEILINGS AND EVEN LOSS OF LOW CEILINGS OCCURRING
OVER SERN NEBRASKA COULD PERSIST INTO EARLY THIS EVENING BUT
CEILINGS SHOULD AGAIN FALL BACK INTO IFR CATEGORY TONIGHT AS A
DISTURBANCE MOVING TOWARD WRN NEBRASKA SPREADS RAIN EWD TONIGHT.
RAIN SHOULD BE FAIRLY WIDESPREAD OVER THE AREA AND LINGER INTO
TUESDAY MORNING OR LATER. IN ADDITION...INSTABILITY WILL BEGIN
FEEDING INTO SERN NEBR/SWRN IA LATE TONIGHT WHICH COULD ALLOW
ISOLATED TSTMS TO MOVE INTO THAT REGION LATE. WITH 18Z TAFS A CB
CLOUD GROUP WAS CARRIED WITH SHRA MENTION TO REFLECT THIS
POSSIBILITY AT KOMA AND KLNK. LITTLE IMPROVEMENT EXPECTED IN
CEILINGS BEFORE 19/18Z.
&&
CHERMOK
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$