Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 292006
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
306 PM CDT SUN MAR 29 2015

.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 302 PM CDT SUN MAR 29 2015

POTENT TROUGH BRINGING WINDY CONDITIONS TODAY IS PULLING AWAY
EASTWARD...SETTING US UP FOR MILD WEATHER FOR THE NEXT FEW DAYS.
SUBJECTIVE 12Z UPPER AIR ANALYSIS INDICATES STRONG UPPER-LEVEL
SHORTWAVE TROUGH FROM ONT/MB BORDER THROUGH WESTERN MN/EASTERN
SD/CENTRAL NEB...WITH UP TO 160M HEIGHT FALLS AT 500MB AS IT RACES
ACROSS THE NORTHERN TIER OF THE CONUS.  DRY AIRMASS REMAINS IN PLACE
AT 850MB...WITH 850MB DEWPOINTS BELOW 0C ACROSS THE ENTIRE CONUS
EXCEPT FOR A SMALL POCKET IN AR/MS. 850MB WINDS OF 45-50KT WERE
NOTED BEHIND THE COLD FRONT EXTENDING FROM MN/IA THROUGH KS...AND
WITH DEEP MIXING TODAY...SURFACE WIND GUSTS APPROACHED 40-45KT
THROUGH THE LATE MORNING TO MID-AFTERNOON.  SURFACE PRESSURE
GRADIENT WAS LOOSENING SLIGHTLY...WITH SURFACE HIGH AT 19Z IN
EASTERN WY/NORTHEAST CO AND SURFACE LOW WELL NORTHEASTWARD IN ONT.

MAIN FORECAST CONCERNS ARE FIRE WEATHER POTENTIAL TOMORROW AND
CONVECTIVE POTENTIAL ON WEDNESDAY.  SURFACE AND MID-LEVEL RIDGE IS
PROGGED TO SLIDE ACROSS THE REGION TONIGHT...WITH RETURN FLOW
ESTABLISHING ITSELF BY AROUND 12Z MONDAY.  WITH SOUTHWESTERLY FLOW
BOTH AT THE SURFACE AND AT MID-LEVELS...MIXING POTENTIAL SHOULD
ALLOW TEMPERATURES TO RISE INTO THE 70S AS MIXING  REACHES AROUND
800MB...BUT STRONG MIXING ALSO SHOULD BRING DOWN LOW DEWPOINTS IN
THE AFTERNOON...EVEN WITH SOME MOISTURE ADVECTION BEHIND THE RIDGE.
CONDITIONS MAY REACH EXTREME FIRE DANGER CRITERIA...AS RH VALUES ARE
CURRENTLY FORECAST TO FALL BELOW 20% IN AT LEAST THE WESTERN CWA
DURING THE AFTERNOON...WITH WINDS AROUND 15KT GUSTING TO AROUND
25KT.  TO AVOID CONFUSION WITH HEADLINES TODAY AND TO GIVE ONE MORE
LOOK AT POTENTIAL FOR RED FLAG CONDITIONS GIVEN LOWER WIND
SPEEDS...WILL HOLD OFF ON FIRE WEATHER HEADLINES.

MILD WEATHER WILL CONTINUE TUESDAY...DESPITE PASSAGE OF A WEAK
SURFACE TROUGH ON MONDAY NIGHT.  WINDS RETURN FROM THE
SOUTH/SOUTHEAST AT THE SURFACE BY TUESDAY AFTEROON...WITH SOUTHERLY
MID-LEVEL WINDS BRINGING MORE ROBUST MOISTURE ADVECTION INTO THE
CENTRAL PLAINS.  THUS...FIRE WEATHER SHOULD NOT BE A CONCERN ON
TUESDAY...DESPITE CONTINUED MILD TEMPERATURES.  A SHORTWAVE TROUGH
IS PROGGED TO DROP OUT OF THE NORTHERN ROCKIES ON
WEDNESDAY...INTENSIFYING AS IT MOVES ACROSS THE NORTHERN PLAINS.
ASSOCIATED WITH THE TROUGH...A STRONG SURFACE COLD FRONT WILL REACH
AROUND EASTERN SD TO CENTRAL NEB BY MIDDAY WEDNESDAY...AND SHOULD
PASS THROUGH NORTHEAST NEB BY AROUND 00Z THURSDAY.  AHEAD OF THE
FRONT...AIRMASS WILL BECOME INCREASINGLY UNSTABLE UNDER CONTINUED
WARM/MOIST AIR ADVECTION...WITH MLCAPE REACHING AROUND 1000-2000
J/KG BY MID-AFTERNOON.  SHOULD BE MORE THAN ENOUGH INGREDIENTS IN
PLACE TO TRIGGER CONVECTION BY MID-AFTERNOON ALONG THE FRONT.  GIVEN
ORIENTATION OF 0-6KM SHEAR VECTORS CLOSE TO PARALLEL WITH THE COLD
FRONT...NOT TO MENTION THE LINEAR FORCING OF THE FRONT
ITSELF...WOULD BE MORE WORRIED ABOUT LINEAR CONVECTION THAN
SUSTAINED SUPERCELLS.  IN EITHER CASE...ADEQUATE INSTABILITY AND
DEEP-LAYER SHEAR SEEM TO BE LIKELY TO COINCIDE ON WEDNESDAY TO ALLOW
NOT JUST A CONVECTIVE THREAT BUT ALSO A POTENTIAL FOR SEVERE WEATHER
ON WEDNESDAY AFTERNOON AND EARLY EVENING.  WILL CONTINUE TO MENTION
THUNDERSTORM POTENTIAL IN THE HWO...THOUGH WILL GO EASY ON THE
SEVERE POTENTIAL FOR NOW AS IT IS STILL A DAY-4 EVENT.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 302 PM CDT SUN MAR 29 2015

AS INSTABILITY WANES THROUGH THE EVENING ON WEDNESDAY...ANY
POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS ALSO SHOULD WANE...AND
THUNDERSTORMS SHOULD BECOME MORE ISOLATED THROUGH THE NIGHT.  FRONT
AND ASSOCIATED PRECIPITATION EASILY SHOULD BE CLEAR OF THE
SOUTHEASTERNMOST CWA BEFORE 12Z...WITH AT LEAST SOME DRY PERIOD ON
THURSDAY IN WAKE OF THE FRONT.  MODELS CONTINUE TO JUMP AROUND
REGARDING RAIN POTENTIAL LATER THURSDAY AND FRIDAY...BUT AT
MOST...IT WOULD BE A LIGHT AND NON-CONVECTIVE RAIN.  HAVE NUDGED
TEMPERATURES DOWNWARD ON THURSDAY AND FRIDAY GIVEN RATHER STRONG MID-
LEVEL COLD AIR ADVECTION AND POTENTIAL FOR SOME CLOUDS AND RAIN.
WARM AIR ADVECTION DOES LOOK LIKE IT WILL RETURN
FRIDAY/SATURDAY...WITH TEMPERATURES MODERATING BACK TOWARD NEAR-
NORMAL READINGS...BUT PATTERN ITSELF IS NOT VERY CLEAR GIVEN
VARIABILITY AMONG MODELS AND RUNS.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1228 PM CDT SUN MAR 29 2015

PRIMARY AVIATION CONCERN TODAY IS THE GUSTY NORTHWEST
WINDS...GUSTING OVER 30 KNOTS THIS AFTERNOON. AS PRESSURE GRADIENT
WEAKENS THIS EVENING THE WINDS WILL SUBSIDE CONSIDERABLY AND
BECOME SOUTHWEST OVER NIGHT. MONDAY MORNING THE GRADIENT WILL
TIGHTEN AGAIN WITH SOUTHWEST WINDS GUSTING TO 20-25 KNOTS. ALSO A
DECK OF BKN-OVC CIGS FL030-050 THAT WILL MOVE THROUGH THIS
AFTERNOON...MOSTLY CLEAR SKIES EXPECTED THIS EVENING AS CLOUDS
DRIFT SOUTHEAST.


&&

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

$$

SHORT TERM...MAYES
LONG TERM...MAYES
AVIATION...NIETFELD



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