FXUS63 KOAX 100814
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
314 AM CDT FRI JUN 10 2011
.DISCUSSION...
OFF AND ON RAIN/THUNDERSTORM CHANCES UNTIL ABOUT THE MIDDLE OF NEXT
WEEK ARE THE PRIMARY FORECAST CONCERNS.
MAIN UPPER AIR PATTERN WILL CHANGE LITTLE OVER THE NEXT WEEK OR
SO...WITH A MEAN TOUGH REMAINING OVER THE WESTERN CONUS...AND
SEVERAL WAVES OF VARYING STRENGTH EJECTING THROUGH THE PLAINS FROM
TIME TO TIME. ONE OF THOSE WAVES WAS IN EASTERN MONTANA THIS MORNING
WITH ATTENDANT JET STREAK NOSING INTO WESTERN NEBRASKA...WHICH
WAS TRIGGERING SCATTERED SHOWERS THERE. THESE MAY SKIRT OUR
NORTHERN CWA THIS MORNING AS THE WAVE LIFTS INTO NORTHERN
MINNESOTA BY THIS AFTERNOON. IN OUR SOUTH...A COLD FRONT SLIPPED
INTO NORTHERN KANSAS AND MISSOURI THIS MORNING. 35KT LOW LEVEL JET
WAS RIDING OVER THAT FRONT...AND MODELS WERE SUGGESTING MORE
CONVECTIVE DEVELOPMENT IN NORTHERN KANSAS BEFORE SUNRISE. THIS
AREA WILL SHIFT TO THE EAST ACROSS OUR SOUTHERN ZONES THROUGH THE
DAY. THUS WILL MAINTAIN A CHANCE FOR SHOWERS/STORMS THERE.
WILL LIKELY SEE A DRY PERIOD TONIGHT AND SATURDAY IN BETWEEN EXITING
NORTHERN PLAINS WAVE AND NEXT SET OF IMPULSES APPROACHING FROM THE
SOUTHWEST. NAM/GFS/ECMWF ALL POINT TO A SIGNIFICANT SHORTWAVE
ROLLING INTO THE PLAINS SATURDAY NIGHT...SPARKING CONVECTION IN THE
HIGH PLAINS BEFORE APPROACHING EASTERN NEBRASKA AFTER MIDNIGHT AS
INCREASING LOW LEVEL JET MAINTAINS STORMS MOST OF THE NIGHT. SEVERE
THREAT LOOKS MARGINAL FOR OUR AREA GIVEN LATE ARRIVAL OF STORMS AND
ONLY MODEST ELEVATED INSTABILITY. HOWEVER MORE RAIN FOR ALREADY
SWOLLEN RIVERS IS NOT THE BEST OF NEWS.
RAIN/STORMS SHOULD CONTINUE THROUGH SUNDAY MORNING BEFORE EXITING TO
THE EAST BY NOON. MORE DEVELOPMENT IN THE AFTERNOON CAN NOT BE RULED
OUT...ESPECIALLY IN OUR SOUTH...GIVEN SOUTHERLY 30KT 850 FLOW
SENDING HIGHER THETA-E AIR BACK INTO THE CWA. THIS CONTINUES SUNDAY
NIGHT AS LOW LEVEL JET STRENGTHENS...BUT UPPER SHORTWAVE IS SHIFTING
TO OUR NORTHEAST AT THE SAME TIME. WILL MAINTAIN A SMALL CHANCE FOR
STORMS SUNDAY NIGHT...THINKING MAIN THREAT WILL BE NORTH AND
NORTHEAST OF THE CWA.
WARMING MID LEVEL TEMPS OF 12-15C AT 700MB WILL SURGE INTO THE AREA
ON MONDAY...HELPING TO SQUELCH DEVELOPMENT DURING THE DAY. BUT OUR
NEXT SHORTWAVE WILL SWEEP INTO THE AREA MONDAY NIGHT...COOLING MID
LEVEL TEMPS AND ALLOWING CONVECTION TO RETURN TO THE AREA. IN
FACT...WE SHOULD HAVE SEVERAL OPPORTUNITIES FOR STORMS MONDAY NIGHT
THROUGH TUESDAY NIGHT AS SEVERAL IMPULSES MOVE OVERHEAD BEFORE
POTENT UPPER TROUGH MOVES EAST OF THE PLAINS. THUS GOING FORECAST OF
AT LEAST SMALL POPS THROUGH TUESDAY NIGHT WERE NOT CHANGED.
GFS AND ECMWF DIVERGE SOMEWHAT CONCERNING UPPER PATTERN AFTER MID
WEEK. GFS SHARPENS WESTERN TROUGH WHICH PUMPS A RIDGE OVER THE
PLAINS KEEPING FORECAST MAINLY DRY AND WARM. THE ECMWF KEEPS A
FLATTER FLOW PATTERN IN THE PLAINS...AND CONTINUES THE OCCASIONAL
RAIN CHANCES AS SHORTWAVES INVADE. WILL MAINTAIN OUR CURRENT DRY
FORECAST FOR THAT PERIOD UNTIL SOME CONSENSUS AMONG MEDIUM RANGE
MODELS CAN BE REACHED.
DERGAN
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
SURFACE LOW PRESSURE OVER NORTHWEST MISSOURI WILL TRACK INTO THE
LOWER GREAT LAKES TODAY...HOWEVER THE MID LEVEL SHORT WAVE TROF IS
STILL MOVING THROUGH THE NORTHERN PLAINS. SURFACE HIGH PRESSURE
WILL BUILD IN WITH NORTHWEST WINDS AT 10 TO 15KTS DECREASING TO
LIGHT AND VARIABLE AFTER 00Z. MVFR/IFR CIGS TO CONTINUE EARLY THIS
MORNING...GRADUALLY LIFTING TO VFR EARLY THIS AFTERNOON AT KOFK AND
KLNK AND EXPECTED TO LINGER AT KOMA. SOME MVFR VSBYS THROUGH 15Z.
ZAPOTOCNY
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...FLASH FLOOD WATCH THROUGH MONDAY MORNING FOR IAZ090.
&&
$$