Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 211832
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
132 PM CDT THU AUG 21 2014

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 232 AM CDT THU AUG 21 2014

SIMILAR TO LAST NIGHT...ENVIRONMENT IS PRIME FOR SCATTERED
CONVECTION THIS MORNING WHICH HAS ALREADY BLOSSOMED OVER THE REGION
ALONG A SFC TROF EXTENDING FROM THE ERN DAKOTAS INTO WRN KS.
ENVIRONMENT IS QUITE MOIST/UNSTABLE WITH PWS APPROACHING 2"/MUCAPES
PEAKING AROUND 3000 J/KG. AND WITH HEALTHY LLVL MOISTURE FEED...IT
IS LIKELY THAT AREAL COVERAGE WILL INCREASE OVER THE NEXT COUPLE
HOURS AND LINGER INTO THE LATE MORNING HOURS.

OTHERWISE...STILL VERY GOOD MODEL AGREEMENT THAT LARGE SCALE FLOW
WILL BE STAGNANT HEADING INTO THIS WEEKEND IN RESPONSE TO HIGH
PRESSURE DOME OVER THE SERN CONUS. HOWEVER...MODELS ARE NOT IN IN
VERY GOOD AGREEMENT WITH RESPECT TO SFC LOW PLACEMENT AND ATTENDANT
SFC BOUNDARIES...THUS MAKING PCPN FCST SOMEWHAT PROBLEMATIC. OVERALL
THOUGH...NOCTURNAL TSTMS OVER THE DAKOTAS WILL BE THE FOCUS FOR BULK
OF TSTM ACTIVITY OVER THE NEXT SEVERAL NIGHTS. OF PARTICULAR
INTEREST IS HIGH POTENTIAL FOR HVY PCPN OVER THE NRN CWA FRIDAY
NIGHT. IN THIS CASE...NAM/GFS/ECM/CMC ALL HAVE BEEN VERY
CONSISTENT THE LAST SEVERAL RUNS ADVERTISING GENEROUS RAINFALL
AMOUNTS OVER NERN NEB. AND GIVEN THIS...FEEL COMFORTABLE ENOUGH AT
THIS POINT TO RAISE POPS TO CATEGORICAL LEVEL.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 232 AM CDT THU AUG 21 2014

TEMP FCST HAVE BECOME SOMEWHAT PROBLEMATIC AS NOW THE GFS AND ECM
ARE DIVERGING ON HOW TO HANDLE ANTICIPATED INTRUSION OF CANADIAN
AIR MASS NEXT WEEK. THE GFS IS STILL ON TRACK BRINGING THE COOLER
AIR MASS SOUTH IN RESPONSE TO AN AMPLIFIED UPPER TROF.
HOWEVER...THE ECM HAS TAKEN A SHARP TURN NOW AND ADVERTISES NEAR
ZONAL FLOW THUS INHIBITING ANY SORT OF SOUTH BOUND COOL AIR ADV.
OBVIOUSLY NOT REASONABLE AT THIS POINT TO CONSIDER INTRODUCING
ANY DRAMATIC TEMP CHANGES UNTIL SITUATION BECOMES MORE CLEAR.
NOTE...GOING POPS ARE ASSUMING COOLER GFS SOLUTION WILL BE
REALIZED WITH PCPN ACTIVITY FOCUSED AROUND COLD FRONT DROPPING
THRU THE REGION.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 123 PM CDT THU AUG 21 2014

POTENTIAL FOR CONVECTION WILL BE A MAJOR CONCERN DURING THE PERIOD
ALTHOUGH AT THIS TIME SHORT RANGE MODELS SHOW BEST POTENTIAL NEAR
THE SOUTHEAST NEBRASKA KANSAS BORDER AFTER 03Z WHERE WEAK SURFACE
BOUNDARY IS EXPECTED TO BE LOCATED. DUE TO UNCERTAINTY IN TIMING
AND AREAL EXTENT HAVE KEPT THUNDER OUT OF TAFS FOR NOW. VFR
CONDITIONS ARE EXPECTED TO PREVAIL OUTSIDE OF ANY CONVECTIVE
ENVIRONMENT.

&&

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

$$

SHORT TERM...DEE
LONG TERM...DEE
AVIATION...FOBERT


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