Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 292326
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
626 PM CDT FRI AUG 29 2014

.SHORT TERM...(TONIGHT THROUGH MONDAY)
ISSUED AT 300 PM CDT FRI AUG 29 2014

OTHER THAN LINGERING CONVECTION THIS EVENING MAIN FOCUS IN SHORT
TERM WILL BE THUNDERSTORM CHANCES/STRENGTH ON SUNDAY AS ACTIVE
PATTERN TO PERSIST THROUGH PERIOD.

AFTERNOON SATELLITE IMAGERY SHOWED UPPER TROUGH MOVING INTO
EXTREME EASTERN NEBRASKA WITH PIVOT POINT NEARING MISSOURI RIVER
AS OF 19Z. TROUGH SHOULD BE KICKED EWD FAIRLY QUICKLY THIS EVENING
BY UPSTREAM WAVE FAST APPROACHING NW NEBR. BUT BESIDES CURRENT
CONVECTION ONGOING TO ERN NEBR WAVE...MAY HAVE TO ACCOUNT FOR SOME
UPSTREAM CONVECTION...WHICH HAD NOT YET DEVELOPED AS OF
19Z...WORKING TOWARD NWRN ZONES FOR A FEW HRS THIS EVENING AND SOME
LAST MINUTE CHANGES PROBABLE. WITH MOISTURE PLENTY AND WAVE
TAPPING SOME MOISTURE OFF OF GULF SYSTEM...SLOW MOVEMENT COULD AID
IN A FEW LOCATIONS RECEIVING HEAVY RAIN. HOWEVER...GIVEN
MODERATELY LIGHT DEEPER SHEAR VALUES PRESENT AND CLOUDS/EARLIER
CONVECTIVE OVERTURNING KEEPING ML CAPE VALUES MODEST...SEVERE
THREAT PROBABLY REMAINING ISOLD AT BEST. THAT SAID...PER SPC MD
1633 WITH LOW LEVEL CAPE AND VORTICITY PRESENT WITH UPPER TROUGH A
BRIEF TOR NOT IMPOSSIBLE ...SPCLY IF CLEAR SLOT INTO SERN NEBR AT
19Z WOULD ALLOW IT TO FURTHER DESTABILIZE BEFORE BEING OVERRUN BY
CLOUDS/LIGHT SHOWERS TO THE WEST. PLAN ON GENERALLY ENDING MOST
POPS BY 06Z. LITTLE/NO CHANGES TO LOWS TONIGHT AND WITH RESIDUAL
MOISTURE AND LIGHT WINDS LEFT IN LATE NIGHT FOG.

SHORT WAVE RIDGING AHEAD OF NEXT TROUGH SHOULD BRING A DRY AND
WARMER DAY ON SATURDAY AND AGAIN LITTLE/NO CHANGES TO TEMPS. LEFT
IN SMALL LATE NIGHT POPS NWRN ZONES SAT NIGHT AS LOW LEVEL
JET/WARM ADVECTION INCREASES AHEAD OF NEXT TROUGH.

ALTHOUGH ELEVATED CONVECTION COULD PERSIST INTO SUN AFTN AIDED BY
LOW LEVEL JET...PER NAM/GFS...12Z ECMWF GENERALLY KEPT AREA DRY
UNTIL 00Z MONDAY WHEN STRONG UPPER JET PUNCHES INTO REGION ON
SOUTH SIDE OF THIS NEXT UPPER TROUGH. DUE TO UNCERTAINTY IN AMOUNT
OF ELEVATED CONVECTION PRECEDING MAIN LATE AFTN/EVENING
DEVELOPMENT LEFT IN MORNING POPS NW 2/3RDS AND DID NOT BREAK UP
THE AFTN PERIOD TO ACCOUNT FOR POSSIBLE HIGHER CHANCES LATE IN
THE AFTN. DID BOOST MAX TEMPS A FEW DEGREES SOUTH ON SUNDAY AS
THAT AREA DID SEEM THE LESS SUSCEPTIBLE TO IMPACT OF MORNING WARM
ADVECTION CLOUDS PSBL PRECIP. STRONG/SEVERE STORM CHANCES APPEAR
HIGHER THAN PAST SEVERAL DAYS AS 0-6KM SHEAR IS STRONGER AND MAX
TEMPS NEARING 90 SHOULD INCREASE MLCAPE VALUES. ALTHOUGH HEAVY
RAIN WILL LIKELY OCCUR WITH THE ACTIVITY AS WELL...VERY HARD TO
PIN DOWN WHERE AXIS OF HEAVIEST WILL OCCUR AS A CASE COULD BE MADE
FOR IT SETTING UP JUST ABOUT ANYWHERE IN OR EVEN POSSIBLY JUST
OUTSIDE THE FA.

ALTHOUGH LABOR DAY WILL BE KEPT DRY FOR NOW...OUTSIDE A LINGERING
MORNING MENTION FAR SE...FAST MOVING FLOW WILL ALLOW APPROACH OF
NEXT WAVE BY AFTN IN NW NEBR. ALSO FRONT SHOVED SOUTH WITH
SUNDAY/S WAVE COULD STALL OUT MONDAY AFTN BEFORE ATTEMPTING TO
LIFT NORTH MONDAY NIGHT. BOTH OF THESE ITEMS COULD ALLOW SOME
ADDITIONAL INCLUSION IN POPS IN LATTER FORECASTS FOR LABOR DAY.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 300 PM CDT FRI AUG 29 2014

BECAUSE OF AFOREMENTIONED SETUP DESCRIBED ABOVE...SMALL POPS WERE
INCLUDED ALL ZONES MON NIGHT AND ACROSS THE SE ON TUE.

OTHERWISE BUILDING UPPER HEIGHTS WITH JET SHIFTING FARTHER N PER
12Z ECMWF/GFS LENT ITSELF TO A DRY FORECAST WED ALONG WITH WARMING
TEMPERATURES. ALTHOUGH PRIOR FORECAST/00Z MODELS SUGGESTED A
CONTINUATION OF THE DRY FORECAST THU...WHICH WAS MAINTAINED...LATEST
GFS/ECMWF ALLOWED A FRONT TO WORK INTO THE NRN ZONES AT LEAST ON
THURSDAY AS AN UPPER WAVE DROPPED SE THROUGH CANADA. THE NEW DAY
7 WILL INCLUDE PRECIP CHANCES WITH THIS SCENARIO AND IF TRENDS
WOULD PERSIST...POPS MAY EVENTUALLY BE INSERTED TO THU PERIOD AS
WELL...SPCLY N.

&&

.AVIATION...(00Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 622 PM CDT FRI AUG 29 2014

SCATTERED SHOWERS AND THUNDERSTORMS IN EASTERN NEBRASKA WILL
GRADUALLY DISSIPATE THIS EVENING...WITH ONLY SMALL CHANCE THEY
WILL AFFECT KOFK OR KOMA. THEN GENERALLY VFR CONDITIONS WILL RULE
THROUGH ABOUT 08Z WHEN FOG AND LOW CLOUDS ARE EXPECTED TO SETTLE
IN. CIGS BELOW FL010 AND VSBYS AT 1SM ARE LIKELY BETWEEN 08Z AND
15Z AT ALL TAF SITES. SCATTERED CLOUDS ARE FORECAST AFTER 05Z WITH
LIGHT NORTHWEST WINDS.

&&

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

$$

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


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