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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KOAX 192042
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
342 PM CDT SUN MAY 19 2013

.DISCUSSION...
-- Changed Discussion --
SHORT TERM FORECAST CONCERNS WILL BE ONGOING SEVERE WEATHER THEN
LINGERING THUNDERSTORMS LATER TONIGHT AND SHOWER AND
THUNDERSTORMS WITH THE CYCLONIC FLOW AROUND THE SLOW MOVING H5 LOW
OVER THE DAKOTAS THROUGH WEDNESDAY.

AS OF MID AFTERNOON...HAVE A COUPLE OF TORNADO WATCHES IN EFFECT
FOR PARTS OF SOUTHEAST NEBRASKA INTO WESTERN IOWA.

THE MORNING OAX SOUNDING...WE STILL HAD AROUND 1 INCH OF
PRECIPITABLE WITH STEEP MID LEVEL LAPSE RATES OF 7.6C/KM.  AT
H300...THERE IS AN EXTENDED 90-110KT JET FROM THE WEST COAST TO THE
TEXAS PANHANDLE.  THIS JET IS FORECAST TO PROGRESS ACROSS OKLAHOMA
TODAY AND CURVE NORTHEAST TO IOWA AND MINNESOTA TONIGHT...WITH UPPER
LEVEL DIVERGENCE FROM NORTHEAST KS...THEN MISSOURI TO EASTERN IOWA
AND WISCONSIN OVERNIGHT.  THE H5 LOW WAS CENTERED OVER WY AND SD
WITH AREAS OF VORTICITY ROTATING NORTHEASTWARD AROUND THE LOW THRU
THE H5 FLOW. THE AREA OF LOW PRESSURE OVER WYOMING IS FORECAST TO
DUMBELL...AND ROTATE INTO NEBRASKA AND THEN NORTHEAST AGAIN INTO
EASTERN SOUTH DAKOTA...AND THEN NORTH DAKOTA DURING THE DAY MONDAY.
THIS WILL CAUSE HEIGHT FALLS OVER THE PLAINS TODAY...THE UPPER
MIDWEST TONIGHT AND THE UPPER MISSISSIPPI VALLEY MONDAY. AT H7/H8
THESE WERE NEARLY STACKED AREAS OF LOW PRESSURE CENTERED OVER THE
SD/ND BORDER WITH LOW PRESSURE EXTENDING SOUTHWARD TOWARD THE NEB/KS
BORDER.  THE CAPPING H7 TEMPERATURES WERE WELL TO THE SOUTH IN OK
AND SOUTHERN MO AND THE BELT OF STRONGER H85 45 TO 50 KT WINDS
STRETCHED FROM TEXAS TOWARD MISSOURI.  THE SWATH OF DEEPER MOISTURE
EXTENDED FROM TX ACROSS OK INTO KS WITH POCKETS IN NEBRASKA.

BY THE START OF THE EVENING PERIOD...INSTABILITY IS EXPECTED TO
RANGE FROM 1000-2500J/KG WITH 0-6KM BULK SHEAR OF 30 TO 55KTS
OVER THE SOUTHEAST THIRD OF THE FORECAST AREA. PER THE SPC
MESOANALYSIS...THE MOST UNSTABLE SURFACE BASED INSTABILITY WAS
LOCATED OVER SOUTH CENTRAL KANSAS AT 2030Z. COMPLEX SHORT WAVE
ENERGY WILL PIVOT NORTHEAST AND ROTATING AROUND THE H5 LOWS. WE
HAVE ONE LINE OF THUNDERSTORMS MOVING THROUGH NOW...HOWEVER INSTABILITY
WILL CONTINUE TO BE DRAWN NORTHWARD INTO THE EARLY EVENING HOURS.

THE GENERAL SOUTHWEST TO NORTHEAST FLOW WILL VEER MORE WITH TIME
...THEN DRYING OF THE DEEP MOISTURE WITH AN EASTWARD SHIFT OF THE
ORGANIZED SEVERE WEATHER. THAT BEING SAID...MOISTURE WILL CONTINUE
TO ROTATE AROUND THE UPPER WITH SOME SHOWER AND THUNDERSTORMS
ACTIVITY ROTATING BACK INTO PARTS OF THE AREA OVERNIGHT. THE MID
TROPOSPHERIC LOW WILL REMAIN OVER THE DAKOTAS MONDAY AND TUESDAY
AND WILL WILL KEEP THE AREA UNDER THE RISK FOR SHOWERS AND
ISOLATED THUNDERSTORMS. HIGHEST POPS WILL BE OVER NORTHEAST
NEBRASKA DURING THIS TIME FRAME. MONDAY THROUGH WEDNESDAY WILL SEE
COOLER TEMPERATURES WILL HIGHS IN THE 60S AND 70S.

DURING THE EXTENDED AS ANOTHER CYCLONE SPINS OVER THE PACIFIC
NORTHWEST...DEEPER MOISTURE WILL RETURN TO THE PLAINS. THIS TOO IS
A SLOW MOVING SYSTEM AND WILL BRING SHOWERS AND THUNDERSTORMS TO
THE REGION FRIDAY INTO SUNDAY.
-- End Changed Discussion --

&&

.AVIATION...
-- Changed Discussion --
..18Z TAFS FOR KOFK...KLNK AND KOMA.

SCATTERED THUNDERSTORMS COULD AFFECT ALL EASTERN NEBRASKA TAF
SITES THROUGH THE EVENING. KOFK WILL SEE SCATTERED THUNDERSTORMS
THROUGH ABOUT 21Z BEFORE A BREAK IN THE ACTION THERE. AT KLNK AND
KOMA...MOST STORMS WILL REMAIN WEST OF THE TAF SITE THROUGH 00Z
BEFORE A BAND OF STORMS SWEEPS THROUGH. WHILE STORMS COULD POP AT
JUST ABOUT ANY TIME DURING THE AFTERNOON AND EVENING...TAFS WERE
WRITTEN TO INCLUDE A 2 TO 4 HOUR WINDOW OF MOST LIKELY STORM
ACTIVITY. EACH ROUND OF STORMS WILL BRING AT LEAST MVFR
CONDITIONS...BUT IFR CIGS/VSBYS CAN BE EXPECTED WITHIN
THUNDERSTORM AREAS. MOST OF THE ACTIVITY SHOULD BE MOVING EAST OF
TAF SITES BY 04-06Z TIME FRAME...BUT MORE SHOWERS WILL LIKELY
FILTER INTO KOFK FROM THE NORTHWEST AFTER 06Z. VFR CONDITIONS ARE
EXPECTED OUTSIDE OF ANY PRECIPITATION.
-- End Changed Discussion --

&&

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

$$

ZAPOTOCNY