FXUS63 KOAX 110919
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
419 AM CDT SAT JUN 11 2011
.DISCUSSION...
CONTINUED OFF AND ON CHANCES FOR PRECIPITATION THROUGH NEXT WEEK
REMAIN THE PRIMARY FORECAST CONCERN.
UPPER WAVE/LOW OVER NORTHERN MINNESOTA WAS LIFTING NORTHEAST THROUGH
THE NORTHERN GREAT LAKES...WITH OUR AREA SEEING GRADUALLY RISING
HEIGHTS IN ITS WAKE. TO OUR WEST...UPPER FLOW WAS BEGINNING TO
RELOAD ITS WESTERN CONUS TROUGH PATTERN AS STRONG NORTHWESTERLY MID
LEVEL JET WAS PUNCHING INTO THE NORTHERN CALIFORNIA COAST. THIS WILL
ESTABLISH A TROUGH ALONG THE WEST COAST THAT WILL HANG AROUND THERE
THROUGH SUNDAY NIGHT BEFORE MODELS FORECAST A GRADUAL TRANSITION
INTO AND THROUGH THE PLAINS. SOUTHWESTERLY FLOW INTO THE CENTRAL AND
NORTHERN PLAINS WILL INDUCE SURFACE LOW PRESSURE IN THE LEE OF THE
ROCKIES FROM MONTANA INTO THE TEXAS PANHANDLE. THIS...IN TURN...WILL
PROMOTE PERSISTENT SOUTHERLY FLOW FROM THE GULF AND SUBSEQUENT LOW
LEVEL MOISTURE INCREASES FOR MUCH OF THE PLAINS.
MEANWHILE AT THE SURFACE...COLD FRONT HAD SETTLED INTO CENTRAL
MISSOURI AND SOUTHEAST KANSAS THIS MORNING. SCATTERED CONVECTION
DEVELOPED ALONG AND NORTH OF THAT FRONT...BUT WILL STAY WELL SOUTH
OF OUR AREA. HOWEVER THAT FRONT WILL BEGIN TO LIFT NORTH LATER TODAY
AND APPROACH THE KANSAS NEBRASKA BORDER ON SUNDAY. MODELS HAVE BEEN
ADVERTISING A SHORTWAVE MOVING INTO THE PLAINS SATURDAY NIGHT AND
THROUGH OUR CWA BY SUNDAY AFTERNOON...AND THE 00Z RUNS ARE NO
DIFFERENT. EXPECT CONVECTION TO FIRE IN THE LATE AFTERNOON IN THE
HIGH PLAINS AIDED BY UPSLOPE FLOW AND INCREASING LOW LEVEL MOISTURE.
ACCELERATING LOW LEVEL JET AHEAD OF SHORTWAVE SHOULD MAINTAIN STORMS
OVERNIGHT ACROSS SOUTHERN NEBRASKA AND NORTHERN KANSAS...REACHING
OUR SOUTHWEST CWA AFTER MIDNIGHT. MODEST THETA-E ADVECTION AND
MOISTURE CONVERGENCE AS PER NAM/GFS SUGGEST SOUTHEAST NEBRASKA AND
SOUTHWEST IOWA WILL SEE THE BRUNT OF THE PRECIPITATION...BUT BROAD
AREA OF LIFT/MOISTURE WILL BRING AT LEAST A CHANCE FOR RAIN TO ALL
OF THE CWA. SEVERE THREAT LOOKS MINIMAL WITH CAPE VALUES LIFTED FROM
850 MB LESS THAN 1000 J/KG.
MOST OF THE PRECIPITATION SHOULD BE MOVING EAST OF OUR AREA DURING
THE AFTERNOON SUNDAY BUT WILL MAINTAIN SMALL CHANCES FOR MUCH OF THE
CWA FOR LINGERING SHOWERS OR STORMS. ANOTHER SHORTWAVE IS FORECAST
TO MOVE INTO THE PLAINS SUNDAY NIGHT WITH ATTENDANT INCREASE IN LOW
LEVEL JET ONCE AGAIN PROMOTING STRONG THETA-E ADVECTION OVER
QUASI-STATIONARY BOUNDARY ALONG THE KANSAS BORDER. RAIN CHANCES WILL
LIFT NORTHEAST ON MONDAY WITH EXITING SHORTWAVE...LEAVING MUCH OF
MONDAY DRY.
WESTERN TROUGH WILL BEGIN MOVING INTO THE PLAINS MONDAY NIGHT AND
TUESDAY. THINK BULK OF PRECIPITATION WILL REMAIN TO OUR WEST MONDAY
NIGHT WITH APPROACH OF UPPER TROUGH. ON TUESDAY THE TROUGH AXIS
SHIFTS INTO THE CENTRAL PLAINS...PROVIDING DIFFLUENT FLOW AND COOLER
TEMPERATURES ALOFT. LOW LEVEL MOISTURE WILL BE IN PLACE AS GFS
PAINTS SURFACE DEW POINTS NEAR 70 ACROSS ALL OF THE CWA. THIS
COMBINATION YIELDS SURFACE-BASED CAPE VALUES OVER 3000 J/KG WITH
MINIMAL INHIBITION. QUESTION WILL BE FRONTAL BOUNDARY PLACEMENT AS
MODELS SUGGEST SURFACE CONVERGENCE WILL BE JUST SOUTH ACROSS
NORTHEAST KANSAS AND NORTHWEST MISSOURI. CONVECTION LOOKS LIKELY BUT
MOST SEVERE STORMS MAY BE JUST OUT OF OUR AREA.
WILL CONTINUE RAIN CHANCES TUESDAY NIGHT...BUT MAY SQUEAK OUT A DRY
DAY OR SO WEDNESDAY INTO THURSDAY BEHIND EXITING TROUGH. HOWEVER
NORTHWEST FLOW REGIME USUALLY SPELLS SPORADIC RAIN CHANCES THIS TIME
OF YEAR. ANOTHER SIGNIFICANT SHORTWAVE IS SLATED TO INVADE THE
PLAINS THURSDAY NIGHT...SO CURRENT FORECAST OF RELATIVELY HIGH POPS
LOOK GOOD THEN.
DERGAN
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
MVFR/IFR/LIFR VSBYS WITH FOG AND PATCHY CIGS ARE EXPECTED THIS
MORNING WITH LINGERING LOW LEVEL MOISTURE AND LIGHT AND VARIABLE
WINDS THRU 14Z. SOME LINGERING LOW CLOUDS NEAR THE MISSOURI RIVER
EARLY ON...HOWEVER THE BULK OF THE LOW CLOUDS HAVE SHIFTED OFF TO
THE EAST. SURFACE HIGH PRESSURE OVER THE NORTHERN PLAINS WILL SLOWLY
MOVE INTO MINNESOTA THIS MORNING. AS THE SURFACE HIGH PRESSURE
SYSTEM CONTINUES TO MOVE ACROSS MINNESOTA...SCATTERED CLOUDS SHOULD
DEVELOP THIS AFTERNOON WITH THE HEATING OF THE DAY. CONDITIONS
SHOULD REMAIN VFR. TONIGHT...THE LOW LEVEL JET WILL INCREASE. LOOK
FOR CLOUDS TO BE ON THE INCREASE TOWARD 06Z.
ZAPOTOCNY
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...FLASH FLOOD WATCH THROUGH MONDAY MORNING FOR IAZ090.
&&
$$