FXUS63 KOAX 252044
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
344 PM CDT SAT JUN 25 2011
.DISCUSSION...
THE MAIN CONCERNS FOR THE NEXT FEW DAYS WILL BE TIMING AND
PLACEMENT OF THUNDERSTORMS AND THE RISK FOR LOCALLY HEAVY
RAINFALL.
ALTHOUGH CONVECTION IS EXPECTED TO DEVELOP IN THE
DAKOTAS...OVERNIGHT...THE THUNDERSTORMS MAY NOT HOLD TOGETHER AS
THEY MOVE FARTHER EAST INTO THE PLAIN. BEHIND THE
MCS...PRECIPITABLE WATER HAS DECREASED TO AROUND AN INCH AND A
QUARTER WITH THE HIGHER PRECIPITABLE WATER FROM EASTERN KANSAS
INTO MISSOURI AND ILLINOIS...CLOSER TO THE SURFACE FRONT. THE
SURFACE FRONT IN KANSAS AND MISSOURI IS EXPECTED TO REMAIN NEARLY
STATIONARY...WHILE THE COLD FRONT IN THE WESTERN DAKOTAS MOVES
FARTHER EAST...AS SHORTWAVE TROUGH ENERGY MOVES EAST ALONG WITH AN
UPPER LEVEL JET. THE LARGER SCALE FORCING FAVORS THUNDERSTORMS
WESTN AND NORTH OF OUR FORECAST AREA. THE 12Z 4KM WRF DOES BRING A
CLUSTER OF THUNDERSTORMS INTO OUR AREA OVERNIGHT AS DOES THE
GFS...HOWEVER THE NAM AND ECMWF ARE MORE DRY. THIS WILL NEED TO BE
WATCHEE AS THE FORECAST SOUNDINGS BECOME UNSTABLE OVERNIGHT AND DO
NOT HAVE SIGNIFICANT INHIBITION. SIMILAR DIFFERENCES ARE FORECAST
FOR SUNDAY AS THE 18Z NAM HAS A CONVECTIVE COMPLEX MAKING IT INTO
NEBRASKA WHILE THE GFS/ECMWF/4KM ARE DRY IN THE NORTH...ALTHOUGH
THE GFS DOES HAVE SOME PRECIP CLOSER TO THE WARM FRONT IN THE
SOUTHERN PART OF THE FORECAST AREA. WARMER MID LEVEL TEMPERATURES
WILL WORK INTO THE FORECAST AREA FOR SUNDAY...HOWEVER DID MENTION
A CHANCE IN THE NORTH IN THE MORNING AND ACROSS PARTS OF THE
FORECAST AREA SUNDAY AFTERNOON. THE DAY ONE RISK FOR EXCESSIVE
RAINFALL RIGHT NOW IS PLACED OVER SOUTH DAKOTA.
THE MID LEVEL TROUGH CONTINUES TO PRESS EASTWARD ACROSS THE
NORTHERN PLAINS AND DRAGS THE COLD FRONT ACROSS THE FORECAST AREA
SUNDAY NIGHT AND MONDAY. THE BETTER FORCING WILL BE ALONG THE
FRONT AND WITH THE LARGER SCALE UPWARD VERTICAL MOTION AHEAD OF
THE MID LEVEL TROUGH. CONTINUE A CHANCE FOR THUNDERSTORMS DURING
THIS PERIOD. THERE IS ABUNDANT MOISTURE AVAILABLE...THUS THE
STORMS MAY PUT DOWN SOME LOCALLY HEAVY RAIN. SUNDAY NIGHT INTO
MONDAY NIGHT...THERE IS STRONGER LOW LEVEL CONVERGENCE ALONG THE
FRONT FROM SOUTHEAST NEBRASKA INTO SOUTHERN IOWA AND NORTHERN
MISSOURI...THUS THIS WHERE THE RISK FOR EXCESSIVE RAINFALL IS
NOTED DURING THIS PERIOD.
TUESDAY THROUGH SATURDAY...TUESDAY MORNING...THE MID TROPOSPHERIC
PATTERN HAS THE TROUGH OVER THE GREAT LAKES...WITH A RIDGE OVER
THE INTERMOUNTAIN REGION INTO THE SOUTHERN US. A CLOSED MID LEVEL
LOW IS APPROACHING THE PACIFIC NORTHWEST. AT THE SURFACE...HIGH
PRESSURE IS CENTERED OVER THE DAKOTAS INTO NEBRASKA. THE PATTERN
DOES NOT CHANGE MUCH THROUGH TUESDAY NIGHT...HOWEVER RETURN FLOW
SETS UP ENOUGH FOR CONVECTION OVER THE WESTERN HIGH PLAINS...AND
INTO THE MISSOURI RIVER VALLEY BY WEDNESDAY MORNING. WEDNESDAY
AFTERNOON THROUGH THURSDAY EVENING...THE SURFACE RIDGE AND HOT
TEMPS WILL TRY TO HINDER TSRA DEVELOPMENT...HOWEVER DURING THIS
TIME...THE TROUGH OFF THE WEST COAST WILL TRAVEL NORTHEAST ACROSS
NEVADA...IDAHO...AND INTO MONTANA. THIS WILL BREAK DOWN THE RIDGE
FROM THE WEST WITH A COLD FRONT PUSHING INTO THE PLAINS FOR
FRIDAY. THE BULK OF THE MORE ORGANIZED PRECIPITATION SHOULD BE
WELL TO THE NORTH...HOWEVER WITH THE FRONT THERE IS STILL A CHANCE
FOR THUNDERSTORMS THURSDAY NIGHT AND FRIDAY. THE CHANCE FOR
SHOWERS AND THUNDERSTORMS MAY LINGER INTO FRIDAY NIGHT AND
SATURDAY DEPENDING ON HOW FAR SOUTH THE BOUNDARY MAKES IT AN IF
THERE IS ENOUGH SUPPORT. NEAR NORMAL TO ABOVE NORMAL TEMPERATURES
ARE FORECAST FROM 0 TO 10 DEGREES TUESDAY THROUGH SATURDAY.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
MCS THAT MOVED THROUGH THE AREA OVERNIGHT WAS OVER THE MID
MISSISSIPPI VALLEY AT 18Z. SOME LINGERING BOUNDARY LAYER MOISTURE
REMAINS OVER EASTERN NEBRASKA AND SOUTHWEST IOWA WITH MVFR CIGS
DEVELOPING. CIGS EXPECTED TO BECOME SCATTERED WITH VFR CONDITIONS BY
00Z BUT MVFR OR IFR CONDITIONS IN FOG LIKELY TO DEVELOP 06Z-12Z.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
FOBERT/ZAPOTOCNY/FOBERT