Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 121128
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
628 AM CDT SAT JUL 12 2014

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 311 AM CDT SAT JUL 12 2014

ACTIVE WEATHER WILL CONTINUE THROUGH TONIGHT.  SUBJECTIVE 00Z UPPER
AIR ANALYSIS INDICATES VERY WEAK UPPER-LEVEL RIDGING OVER THE
CENTRAL PLAINS...WITH LARGELY ZONAL FLOW ACROSS THE CONUS AND VERY
WEEK 500MB HEIGHT GRADIENT.  UPPER-LEVEL 80-95KT JET STREAK WAS
NOTED ACROSS NORTHERN MT THROUGH ND/NORTHERN SD AND TO NORTHERN MN.
850MB DEWPOINTS OF 16C+ EXTENDED FROM NORTHEAST CO/EASTERN WY ACROSS
WEST TO NORTHEAST NEB AND INTO SD/SOUTHWEST MN...AND 850MB BOUNDARY
WAS NOTED FROM NORTHEAST CO ACROSS SOUTHWEST TO NORTHEAST NEB TO
SOUTHWEST MN.  SURFACE LOW AT 07Z WAS CENTERED IN EASTERN CO...WITH
SURFACE FRONT EXTENDING THROUGH WESTERN NEB TO CENTRAL SD TO CENTRAL
MN.  ONGOING SHOWERS/THUNDERSTORMS WERE PRODUCING HEAVY RAINFALL
ACROSS NORTHEAST NEB/NORTHWEST IA THIS MORNING IN MOISTURE-RICH
ENVIRONMENT.

MAIN FORECAST CONCERN IS CONVECTIVE POTENTIAL TODAY THROUGH TONIGHT.
 DIFFERENTIAL HEATING TODAY WILL SHARPEN FRONTAL BOUNDARY AS SURFACE
FRONT DROPS SOUTHWARD INTO NORTHEAST NEB/NORTHWEST IA THIS
MORNING...AND TOWARD CENTRAL NEB TO WEST CENTRAL IA BY MID-
AFTERNOON.  WITH ADEQUATE EFFECTIVE BULK SHEAR PROGGED ALONG AND
BEHIND THE FRONT...AND PLENTY OF INSTABILITY...SHOULD SEE
THUNDERSTORMS DEVELOP ALONG THE FRONT AS IT DROPS INTO THE AREA.
SOME QUESTION ABOUT WHETHER THERE WILL BE A BREAK IN PRECIP IN WAKE
OF MORNING CONVECTION BEFORE REDEVELOPMENT LATER TODAY...AND WOULD
NOT BE SURPRISED TO SEE SEVERAL HOURS THAT ARE DRY OR MOSTLY DRY
ACROSS THE CWA FROM LATE MORNING THROUGH EARLY AFTERNOON...BUT FOR
NOW...HAVE KEPT POPS IN THE NORTHWESTERN CWA THROUGHOUT.  FRONT IS
PROGGED TO SLOWLY DROP SOUTH THROUGH THE CWA FROM THIS AFTERNOON
THROUGH THE EVENING HOURS...BRINGING SHOWERS/THUNDERSTORMS WITH
AND BEHIND IT. HAVE EDGED TIMING OF FRONT A LITTLE FASTER
TONIGHT...WITH A TIGHTER POP GRADIENT ALONG/BEHIND THE FRONT AS
MODELS INDICATE SHOWERS/STORMS WILL REMAIN IN A RELATIVELY NARROW
BAND. PRECIP SHOULD CLEAR OUT OF THE CWA BY 12Z AND PERHAPS
EARLIER...WITH FRONTAL PRECIPITATION AREA STAYING SOUTH OF THE CWA
THROUGH SUNDAY.

WHILE WIND SHIFT WILL PASS THROUGH THE CWA TONIGHT...THE
TEMPERATURE/DEWPOINT BOUNDARY WILL LAG QUITE A BIT...DROPPING OUT OF
THE DAKOTAS ON LATE SUNDAY.  DRY CONDITIONS ARE EXPECTED SUNDAY
MORNING...BUT HAVE INCREASED AFTERNOON POPS IN THE NORTHEAST CWA AS
MODELS CONTINUE TO INDICATE SHOWERS AND POTENTIALLY ISOLATED
THUNDERSTORMS AS REINFORCING SHORTWAVE MOVES THROUGH THE NORTHWEST
FLOW...WHILE GREAT LAKES TROUGH CONTINUES TO DIG IN.  FORCING AND
INSTABILITY SHOULD WANE QUICKLY IN THE EVENING...AND HAVE LIMITED
POPS TO JUST THE AFTERNOON FOR NOW.  MODELS ARE QUITE MIXED ABOUT
WHETHER OR NOT TO DEVELOP PRECIPITATION IN THE SOUTHERN/SOUTHEASTERN
CWA LATE SUNDAY NIGHT...AND HAVE LEFT MENTION OUT FOR NOW.  THEY
ALSO EXHIBIT QUITE A BIT OF VARIABILITY REGARDING HOW FAR INTO THE
SOUTHERN CWA TO DEVELOP PRECIPITATION ON MONDAY MORNING...BEFORE IT
SHIFTS SOUTHWARD AND OUT OF THE AREA IN THE AFTERNOON.  GIVEN
COOL/DRY AIRMASS INVADING THE CWA...HAVE SHADED GRIDS MORE TOWARD
THE SOUTHWARD SOLUTIONS.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 311 AM CDT SAT JUL 12 2014

DRY AND MUCH COOLER AIRMASS IS STILL PROGGED TO DROP INTO THE PLAINS
THROUGH THE WEEK...WITH HIGH TEMPERATURES NOT EXPECTED TO REACH THE
80S AGAIN UNTIL FRIDAY.  THOUGH CWA WILL BE ON THE WESTERN EDGE OF
THE INFLUENCE OF THE STRONG GREAT LAKES LOW...TEMPERATURES WILL BE
MUCH COOLER THAN NORMAL AND DEWPOINTS WILL BE QUITE LOW.  BY
FRIDAY/SATURDAY...UPPER-LEVEL RIDGING IS EXPECTED TO EDGE EASTWARD
FROM THE ROCKIES TOWARD THE PLAINS...AND MORE SEASONABLE WEATHER
SHOULD RETURN TO THE AREA.  THERE IS SOME INDICATION THAT THE NEXT
CHANCE FOR PRECIPITATION WOULD BE NEXT WEEKEND...BUT CONFIDENCE IN
TIMING IS VERY LOW AS BLOCKING PATTERN BREAKS DOWN...AND HAVE KEPT
FORECAST DRY FOR NOW.

&&

.AVIATION...(12Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 625 AM CDT SAT JUL 12 2014

SFC CDFNT WILL MOVE SOUTHEAST ACROSS THE TAF SITES THROUGH THE DAY
TODAY. VARIABLE WIND DUE TO OVERNIGHT CONVECTION WILL GIVE WAY TO
SOUTHEAST AT KOMA/KLNK AND E AT KOFK FOR A TIME THIS MORNING
BEFORE THE WINDS VEER THROUGH THE DAY BEFORE FROPA...THEN BECOME
NORTH/NORTHEAST BEHIND THE FRONT. ALTHOUGH A LIGHT SHRA WILL BE
POSSIBLE AT KOFK IN THE NEXT HOUR OR TWO...THE BETTER CHANCE OF
SHRA OR EVEN AN TSRA WILL OCCUR AT KOMA/KLNK AFTER 22Z BEHIND THE
FRNT. SKIES WILL GENERALLY CLEAR TONIGHT BEHIND THE FRONT.

&&

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

&&

$$

SHORT TERM...MAYES
LONG TERM...MAYES
AVIATION...BOUSTEAD


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