Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 120453
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1153 PM CDT FRI APR 11 2014

.SHORT TERM...(TONIGHT THROUGH MONDAY)
ISSUED AT 335 PM CDT FRI APR 11 2014

COMPLEX FORECAST WITH MANY CONCERNS CONTINUES IN THE SHORT TERM.
FIRST IS WHETHER SMALL CONVECTION CHANCES REMAIN WARRANTED
TONIGHT/SATURDAY MORNING ENERN ZONES. WARM FRONT SETTING UP N/NE
OF FORECAST AREA THIS AFTN WITH SMALL CU FIELD MARKING LOW LEVEL
CONVERGENT ZONE. MOISTURE REMAINS SPARSE...ALTHOUGH SOME MID 30S
DWPTS CNTRL NEBR COULD FEED INTO BOUNDARY THROUGH EARLY TONIGHT
BEFORE STRENGTHENING LOW LEVEL JET FEEDS IN SOMEWHAT HIGHER
MOISTURE BY MORNING. APPEARS FRONT WILL REMAIN MOSTLY TO THE NORTH
OR EAST OF THE REGION OVERNIGHT AND LIMITED MOISTURE COULD PUT ANY
ELEVATED ACTIVITY FARTHER REMOVED FROM FA...I.E. PARCELS TAKING
LONGER TO SATURATE IN LIFT.  MOST SHORTER TERM MODELS HAVE BACKED
OFF ON GENERATING PCPN OVER THE AREA BUT DID LEAVE IN SMALL POPS
LATE TNGT THROUGH SAT MORNING MAINLY IA ZONES.

MOISTURE/SOME LOWER CLOUDS LIKELY TO SPREAD INTO SERN ZONES
SATURDAY BEFORE MIXING OUT IN THE AFTN. ALTHOUGH A WEAK BOUNDARY
SLIPS SWD TO NEAR OMA/LNK DURING THE AFTN...MAIN COLD FRONT AND
BETTER THERMAL GRADIENT WAS FARTHER N WITH LOW LEVEL CONVERGENCE
ALONG BOUNDARY IN OUR FA FAIRLY WEAK. IT DOES APPEAR DWPTS WILL
LOWER AGAIN NRN ZONES WITH MIXING WITH AN INCREASED FIRE DANGER
RISK NORTH. AN ELEVATED MIXED LAYER STILL FORECAST TO SET UP OVER
BOUNDARY KEEPING MOST OF THE AREA CAPPED UNTIL AFTN HEATING
ATTEMPTS TO WEAKEN IT...ESPECIALLY SERN ZONES. FOR INSTANCE NAM
FORECAST SOUNDING WEAKENED CAP AT FNB BUT KEPT A FAIRLY STRONG
ONE IN PLACE AT KOMA/KLNK. 12Z 4KM WRF DOWNPLAYED ANY CONVECTION
THROUGH 00Z SUNDAY WHILE 12Z ECMWF KEYED ON SWRN IA BY
00Z...FAIRLY CONSISTENT WITH PRIOR RUN. ALTHOUGH GFS/NAM HINTED AT
SOME DEVELOPMENT BY 00Z...THEIR MAIN FOCUS WAS MORE WITH/ALONG
STRENGTHENING LOW LEVEL JET SATURDAY EVENING. ADJUSTED FORECAST
SLIGHTLY TO DELAY CHANCES TIL MID AFTN AND WITHHELD LIKELY POPS
UNTIL THE EVENING HOURS SPREADING LIKELY/CATEGORICAL POPS FROM FAR
E THEN WSW THROUGH THE EVENING. DEEP SHEAR ENOUGH TO PROVIDE A
CONDITIONAL SEVERE THREAT WHEN/IF STORMS DEVELOP. DOES APPEAR SOME
POTENTIAL FOR SIGNIFICANT RAINS SRN ZONES NEAR LOW LEVEL JET
FOCUS.

AS UPPER TROUGH BEGINS MOVING EAST ON SUNDAY...STRONG FRONTOGENETICAL
FORCING COULD SET UP DECENT PRECIPITATION BAND/BANDS AIDED BY
TROUGHS RELATIVELY SLOW MOVEMENT AND MODEST MOISTURE GETTING
PULLED INTO SYSTEM. QUESTION SHIFTS...UNFORTUNATELY GIVEN TIME OF
YEAR...TO PHASE. NAM ESPECIALLY COOLS BOUNDARY LAYER OFF
SIGNIFICANTLY POINTING TO SLEET/SNOW MORESO THAN RAIN NWRN ZONES.
USING BLEND OF WARMER ECMWF AND COLDER NAM KEPT PRECIP FOR NOW A
RAIN/SNOW MIX SUN AFTN NWRN 1/2 OR SO THEN SPREADING R/S OVER REST
OF ZONES SUN NIGHT WITH SNOW ON NWRN FRINGE. ALSO ADJUSTED HOURLY
TEMPS SUNDAY FOR STEADY/FALLING NW WITH EARLY HIGH SE. SPEED OF
SYSTEM AND CONVECTION EVOLUTION LIKELY TO CAUSE FUTURE
ADJUSTMENTS.

GENERALLY DISCOUNTED NAM FOR MONDAY WITH SLIGHTLY SLOWER/SHARPER
TROUGH KEEPING LINGERING PRECIP ACROSS SRN ZONES INTO THE AFTN AS
ECMWF/GFS OFFERED LITTLE SUPPORT. NONETHELESS...CONTINUED COOL
WITH MUCH BELOW NORMAL TEMPS.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 335 PM CDT FRI APR 11 2014

MODERATING TEMPERATURES IN TUE/WED PERIOD AS NEXT TROUGH
APPROACHES...ALTHOUGH GFS WAS A LITTLE S OF ECMWF. THIS NOT ONLY
BROUGHT COOLER READINGS BACK INTO NWRN ZONES ALREADY BY WED BUT
ALSO PUT BAROCLINIC ZONE INTO REGION WITH SOME PRECIP THREAT. FOR
NOW KEPT WED DRY AND BOOSTED TEMPS SERN ZONES WHERE BOTH MODELS
SUGGESTED 60S. WITH FAIRLY COLD AIR FEEDING IN BEHIND
TROUGH...MENTIONED R/S MIX NW ZONES AS H85 TEMPS DROP TO AT LEAST
-5 C...ALTHOUGH PRECIP COULD BE ENDING AS COLDER AIR ARRIVES.
MODEL BLEND INDICATED SMALL POPS TO BE CONTINUED INTO FRIDAY AS
ANOTHER WAVE CROSSES PLAINS...AND THERE WERE MAINTAINED.  BUT
CONFIDENCE PRETTY LOW REGARDING THIS.

&&

.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1149 PM CDT FRI APR 11 2014

MVFR CIGS ARE LIKELY TO DEVELOP BETWEEN 12Z AND 18Z AT KLNK AND
KOMA AS LOW LEVEL MOISTURE WORKS NORTH FROM KANSAS AND OKLAHOMA
OVERNIGHT. A COLD FRONT DROPPING SOUTH THROUGH EASTERN NEBRASKA
WILL PASS KOFK BY 18Z...SWITCHING WINDS TO THE NORTH THERE WITH
SPEEDS NEAR 12KT. THE FRONT WILL ONLY SLOWLY DRIFT SOUTH THROUGH
THE AFTERNOON...AND LIMP THROUGH KLNK AND KOMA AREAS BETWEEN 00Z
AND 06Z. SCATTERED SHOWERS OR THUNDERSTORMS ARE POSSIBLE ALONG THE
FRONT AFTER 21Z...BUT IT APPEARS MOST ACTIVITY WILL DEVELOP SOUTH
OF KLNK AND KOMA TAF SITES AND REMAIN SOUTH THROUGH THE END OF THE
TAF PERIOD.

&&

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

$$

SHORT TERM...CHERMOK
LONG TERM...CHERMOK
AVIATION...DERGAN



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