Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 251715
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1215 PM CDT MON AUG 25 2014

.UPDATE...
ISSUED AT 1031 AM CDT MON AUG 25 2014

MID MORNING REGIONAL RADAR MOSAIC INDICATES THAT A WEAKENING MCS
CONTS TO TRACK ENE THROUGH CNTRL NEB AND WILL SOON MOV INTO
EASTERN NEB. LATEST SHORT RANGE MODELS GUIDANCE INDICATES THAT
THIS SYSTEM WILL CONT TO WEAKEN AS IT SHIFTS INTO THE AREA AS THE
NOCTURNAL LOW-LEVEL JET WEAKENS AND BACKS WITH TIME. HAVE
INCREASED THE POPS IN THE WRN CWA FOR THIS ACTIVITY AS IT MOVES
IN...BUT WE SHOULD SEE A DECREASE IN COVERAGE AS WE GO THROUGH THE
MORNING.

SUBSIDENCE IN THE WEAK OF THE MCS...AS WELL AS LARGE-SCALE HEIGHT
RISES THROUGH THE DAY TODAY MAKE CONVECTIVE REDEVELOPMENT
UNCERTAIN FOR THE AFTERNOON TIME PERIOD. UPPER AIR ANALYSIS AND
MID MORNING WATER VAPOR IMAGERY DO INDC A WEAK SHRTWV TROUGH OVER
UT/WRN CO BUT THIS LIKELY WON`T MAKE IT TO OUR AREA UNTIL TONIGHT.
IN ADDITION THE CLOUD DEBRIS FROM THE MORNING ACTIVITY WILL LIKELY
LIMIT AFTN INSTABILITY. WITH THIS THINKING IN MIND WE HAVE REMOVED
AFTERNOON POPS FROM THE FA AFTER CURRENT MCS DISSIPATES. WE HAVE
ALSO TRIMMED HIGHS IN THE NRN CWA WHERE CLOUDS ARE EXPECTED TO
PERSIST THE LONGEST. NO OTHER CHANGES PLANNED ATTM WITH CONVECTIVE
CHANCES INCREASING DURING THE OVERNIGHT HOURS.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 246 AM CDT MON AUG 25 2014

...WET WEEK SETTING UP WITH POTENTIALLY LOCALLY HEAVY RAIN BUT
OVERALL LOW SEVERE THREAT...

THUNDERSTORM ACTIVITY CURRENTLY ACROSS THE MID MISSOURI RIVER
VALLEY WILL BE EAST OF THE AREA BY 12Z. WILL HAVE TO WAIT FOR THE
NEXT IMPULSE MOVING OUT OF NORTHEAST COLORADO TO ARRIVE LATER
TODAY TO GENERATE ANY PRECIPITATION...SO MOST OF THE MORNING WILL
LIKELY BE DRY WITH PRECIP CHANCES INCREASING THIS AFTERNOON...
ESPECIALLY ACROSS NORTHEAST NEBRASKA. MEANWHILE...A FRONTAL
BOUNDARY WILL REMAIN STALLED FROM NORTHEAST KANSAS THROUGH CENTRAL
IOWA TODAY WITH NORTHEASTERLY WINDS PREVAILING. HIGH TEMPS WILL
AGAIN RANGE FROM THE MID 70S NEAR THE NE/SD BORDER TO THE MID 90S
NEAR THE KS/NE BORDER.

NUMEROUS SHOWERS AND THUNDERSTORMS SHOULD DEVELOP TONIGHT AS
ANOTHER IMPULSE FROM THE MEAN SOUTHWESTERN TROUGH EJECTS OFF THE
FRONT RANGE. PW VALUES INCREASE TO 1.50 TO 1.75 INCHES... WHICH
IS IN THE 90-97% CLIMATOLOGICAL PERCENTILE BASED ON NAEFS MODEL.
LOCALLY HEAVY RAINFALL WILL BE POSSIBLE WITH AREAS ALONG/NORTH OF
I80 EASILY PICKING UP ONE HALF TO ONE INCH OF RAINFALL TAPERING TO
LOWER AMOUNTS FURTHER SOUTH AS YOU GET CLOSER TO THE STALLED
SURFACE FRONT.

WEAK IMPULSE SHOULD STILL BE MOVING THROUGH THE REGION TUESDAY
MORNING WITH SHOWERS STILL LIKELY. PERSISTENT EASTERLY FLOW
COMBINED WITH SUBSIDENCE BEHIND THE FIRST WAVE SHOULD ALLOW FOR
LESS AREAL COVERAGE IN THE AFTERNOON AND SOME AREAS NORTH OF I80
COULD EVEN BE DRY ALTOGETHER. THIS WILL BE IN ADVANCE OF THE NEXT
IMPULSE THAT MOVES OUT OF THE MEAN TROUGH TUESDAY NIGHT. MODELS
SUGGEST THIS IMPULSE COULD BE STRONGER THAN THE FIRST ONE EXPECTED
TONIGHT. PW VALUES REMAIN RATHER MOIST AT 1.75 TO 2 INCHES...AGAIN
WELL WITHIN THE 90-97% NAEFS CLIMATOLOGICAL PERCENTILE. THIS WILL
RESULT IN ANOTHER NIGHT OF LOCALLY HEAVY RAINFALL WITH 1 TO 2
INCHES OF POTENTIAL QPF OVER A LARGE PORTION OF THE FORECAST AREA.
THE REGION IS ALSO WITHIN A SLIGHT RISK OF EXCESSIVE RAINFALL.
HOWEVER...BELIEVE WE CAN HANDLE THE RAIN SINCE IT WILL BE SPREAD
OUT OVER A COUPLE OF DAYS...THUS NO PLANS FOR ANY FLOOD HEADLINES
AT THIS TIME.

THE WET PATTERN CONTINUES INTO WEDNESDAY WITH NO MAJOR PATTERN
CHANGE. SCATTERED TO NUMEROUS SHOWERS WILL LIKELY CONTINUE.

OVERALL SEVERE THREAT APPEARS LOW WITH MAIN FOCUS ON HEAVY RAIN
POTENTIAL.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 246 AM CDT MON AUG 25 2014

PERSISTENT WET PATTERN WILL REMAIN WEDNESDAY NIGHT AND THURSDAY
WITH HIGH PW VALUES REMAINING ACROSS THE REGION. SHOWERS/STORMS
WILL REMAIN LIKELY DURING THIS PERIOD...WITH ANOTHER NIGHT OF
POTENTIAL HIGH QPF WITH ANOTHER ONE HALF TO ONE AND ONE HALF
INCHES OF RAIN EXPECTED THROUGH DAYBREAK THURSDAY. AGAIN THE AREA
IS IN A DAY 3 SLIGHT RISK FOR EXCESSIVE HEAVY RAINFALL. BY THIS
TIME...WILL HAVE TO MONITOR FOR POTENTIAL RIVER RISES AND ANY
ASSOCIATED FLOODING THAT COULD RESULT.

THE WET PATTERN CONTINUES INTO FRIDAY AND SATURDAY AS THE UPPER
TROUGH SLOWLY MOVES ACROSS THE PLAINS. THE GFS MODEL HAS BEEN TOO
FAST MOVING THIS TROUGH EAST THE LAST SEVERAL DAYS. SLOWER ECMWF
SEEMS TO BE MORE LIKELY.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1210 PM CDT MON AUG 25 2014

AN INCREASE IN RAIN AND CONVECTION IS EXPECTED AT THE TAF SITES
OVER THE NEXT 24 HOURS...BUT INITIALLY CONDS WILL REMAIN VFR
THROUGH TODAY. PRESSURE RISES MOVING THROUGH EASTERN NEB HAS
ALLOWED FOR GUSTY NORTH WINDS THROUGH THE MORNING BUT THESE WILL
START TO WEAKEN AND BACK TO THE NE WITH TIME TODAY. CNTRL NEB
CONVECTION SHOULD MISS THE TAF SITES THIS AFTN...BUT AS THE LOW-
LEVEL JET INCREASES TONIGHT WE SHOULD SEE RAIN MOV INTO THE TAF
SITES WITH MVFR VISBY AT TIMES AFTER 06Z. MAY ALSO SEE SOME
THUNDER BUT TIMING IS TO UNCERTAIN ATTM TO TIME INTO THE TAF
SITES.

&&

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

&&

$$

UPDATE...
SHORT TERM...DEWALD
LONG TERM...DEWALD
AVIATION...


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