Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 191109
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
609 AM CDT TUE AUG 19 2014

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 310 AM CDT TUE AUG 19 2014

WV IMAGERY THIS MORNING SHOWING 2 DISTINCT SHORTWAVE TROFS...ONE OFF
THE WEST COAST AND THE OTHER APPROACHING THE WRN GREAT LAKES.
MEANWHILE SFC LOW PRESS WAS SITUATED IN MN WITH A FRONTAL BNDRY
EXTENDING SW INTO NW KS. CONVECTION ASSOCIATED WITH THE BNDRY OVER
NRN KS THIS MORNING WAS GRADUALLY SHIFTING TO THE SE WITHIN AREA OF
ISENTROPIC UPGLIDE.

LATEST MODELS IN AGREEMENT NRN FLOW WESTERLIES WILL BE PROGRESSIVE
THE NEXT SEVERAL DAYS UNTIL LATER THIS WEEK WHEN A UPPER LEVEL HIGH
PRESS DOME BECOMING ESTABLISHED OVER THE SERN CONUS. PCPN CHANCES
DURING THIS TIME ARE SOMEWHAT PROBLEMATIC...INITIALLY REVOLVING
AROUND A MEANDERING SFC BNDRY FOLLOWED BY A WARM FRONT LIFTING THRU
THE REGION.

FOR TODAY...DAYTIME HEATING COUPLED WITH A MOISTURE RICH ENVIRONMENT
WILL PUSH MUCAPES TO 4500J/KG ALONG A NARROW AXIS ALONG THE NEB/KS
BORDER AND INTO NRN MO. THE GFS/ECM/CMC ALL SUGGEST CAPPING WILL BE
A FACTOR THIS AFTN INHIBITING CONVECTIVE DEVELOPMENT INVOF THE SRN
CWA. THE NAM ON THE OTHER HAND PROGS THE CAP BREAKING WITH
CONVECTION DEVELOPING. FCST HIGHS THIS AFTN ARE NOWHERE CLOSE TO
CONVECTIVE TEMPS...AND TEND TO BELIEVE ANY TSRA THAT DOES DEVELOP
WILL BE FOUND SE OF THE CWA WHERE THE GFS/ECM/CMC SHOW CAP
WEAKENING.  TSTM CHANCES WILL BE BETTER TONIGHT WHEN LLVL JET CRANKS
UP WITHIN AREA OF STRONG AGEO LIFT ASSOC WITH MID LYR FRONTOGENESIS.
EXPECT INITIATION TO BE CENTERED AROUND STOUT BNDRY LYR THETA-E
CONVG AXIS ORIENTED W-E. ON WED...STRENGTHENING LLVL SRLY FLOW OVER
THE CNTRL PLAINS IS PROGGED TO PUSH THE SFC BNDRY NWD INTO THE
DAKOTAS/MN BY EARLY WED EVENING. THUS BULK OF PCPN ACTIVITY WILL BE
FOUND NORTH...BUT CANNOT DISCOUNT SOME TSTMS DEVELOPING OVER THE NRN
CWA WED EVENING. THUR NIGHT...A DEEP UPPER TROF SITUATED OVER THE
WRN CONUS WILL EJECT SHORTWAVE ENERGY INTO THE CNTRL PLAINS WITH
DPVA INDUCING LEESIDE SFC LOW PRESSURE. AS ATTENDANT WARM FRONT
LIFTS NWD...EXPECT CONVECTION TO FIRE ALONG THE BNDRY AS IT
APPROACHES THE SRN CWA. AGAIN...ENVIRONMENT WILL BE MOISTURE RICH
AND WILL LIKELY LEAD TO LOCALLY HEAVY RAINFALL DURING THE OVERNIGHT
HOURS.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 310 AM CDT TUE AUG 19 2014

MAIN FEATURE OF INTEREST IN THE EXTENDED PDS IS DEVELOPMENT OF A
BROAD UPPER TROF OVER THE PAC NW IN RESPONSE TO BLOCKING HIGH PRESSURE
DOME OVER THE SERN CONUS. MEDIUM RANGE MODELS AT THIS POINT
GENERALLY AGREE THAT ANOTHER RELATIVELY COOL CANADIAN AIRMASS WILL
SWEEP INTO THE CNTRL PLAINS BY EARLY NEXT WEEK. MATTER OF FACT...MAX
TEMPS MON AND TUES MAY WELL END UP BEING JUST A BIT BELOW NORMAL.
MEANWHILE...PCPN CHANCES DURING THIS TIME WILL ONCE AGAIN BE
CENTERED AROUND A RATHER SLOW MOVING COLD FRONTAL FOLLOWED BY
ANOTHER LATE PD LIFTING WARM FRONT. POPS IN GOING FCST LOOK
REASONABLE STILL...THUS NO MAJOR CHANGES NEEDED.

&&

.AVIATION...(12Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 608 AM CDT TUE AUG 19 2014

ALTHOUGH PATCHY FOG IS POSSIBLE FOR A FEW HOURS AFTER
SUNRISE...IT DID NOT APPEAR TO BE WIDESPREAD ENOUGH TO INCLUDE IN
TAF FORECASTS. OTHERWISE LIGHT WINDS AND VFR CONDITIONS ARE
EXPECTED INTO THIS EVENING. A WARM FRONT LIFTING NORTH ACROSS ERN
NEBR TONIGHT WILL LIKELY BRING TSTMS TO THE REGION WITH BRIEF MVFR
CONDITIONS POSSIBLE. CHANCES APPEARED A LITTLE HIGHER AT KOFK AND
KOMA SO A PROB30 GROUP WAS INTRODUCED WITH 12Z FORECAST AT THOSE 2
SITES NEAR AND AFTER MIDNIGHT.

&&

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

$$

SHORT TERM...DEE
LONG TERM...DEE
AVIATION...CHERMOK



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