FXUS63 KOAX 231722
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1222 PM CDT SAT OCT 23 2010
.UPDATE...
UPDATED THE FORECAST TO INCREASE HIGHS THIS AFTERNOON AND ADJUST
SFC WINDS. PRECIP CHANCES STILL LOOK HIGHER FM ECNTRL AND NE NEB
INTO WRN IA.
&&
.DISCUSSION...
SFC LOW PRESS WAS OVR NCNTRL KS WITH A WRMFNT AND CLEARING INTO SE
NEB. TEMPS WERE WARMING INTO THE 70S ACRS MUCH OF ECNTRL AND SE
NEB INTO SW IA. THE H5 LOW WAS CNTRD OVR WRN NEB. ISO TO SCT TSRA
ARE EXPECTED TO DEVELOP LATER THIS AFTERNOON WITH HEATING AND A
WARM FRONT LIFTING NORTH AND UVV ASSOCIATED WITH THE UPR LOW.
ONE CONCERN WITH THE LACK OF DEEPER RH WITH THE DRY SLOT...SO
ALTHOUGH THERE IS SUFFICIENT INSTABILITY AND SHEAR FOR SEVERE
STORMS...THE RH MAY LIMIT THE COVERAGE. HAVE HIGH IN THE 70S
NORTH AND THE UPR 70S SOUTH.
&&
.PREV DISCUSSION... /ISSUED 321 AM CDT SAT OCT 23 2010/
DISCUSSION...
SHOWERS AND THUNDERSTORMS MOVING THROUGH EXTREME SOUTHEAST
NEBRASKA AND SOUTHWEST IOWA EARLY THIS MORNING WILL MOST LIKELY BE
EAST OF THE CWFA BOUNDARY BY 12Z...THUS WILL USE AN EARLY MORNING
PERIOD TO COVER AT ZONE ISSUANCE. OTHERWISE...SURFACE LOW NEAR THE
CO/KS BORDER REGION WILL PUSH EAST TO SCENTRAL NE THROUGH THIS
AFTERNOON/EVENING AS A FRONTAL BOUNDARY DEVELOPS EAST OF THE
LOW...IN RESPONSE TO DIFFERENTIAL HEATING THAT SHOULD TAKE PLACE
AS A DRY SLOT MOVES INTO THE REGION. MOST OF THE CWFA COULD BE DRY
THIS MORNING AFTER 12Z...ALTHOUGH THERE WILL STILL BE A SMALL
CHANCE OF -SHRA AND ISOLATED THUNDERSTORMS ALONG/NORTH OF
DEVELOPING BOUNDARY ACROSS NORTHEAST NEBRASKA AND NORTHWEST IOWA.
BELIEVE THREAT FOR THUNDERSTORMS INCREASES BY 21Z THOUGH ALONG AND
NORTH OF AFOREMENTIONED BOUNDARY...MAINLY NORTH OF I80 WHERE SHEAR
AND INSTABILITY COMBINATION COULD PROVIDE A NARROW WINDOW OF
SEVERE POTENTIAL FROM 21Z-03Z...BY WHICH TIME ANY STORMS WOULD BE
PUSHING EAST INTO NORTHERN IOWA. BULK SHEAR VALUES AROUND 40KTS
ALONG THE BOUNDARY WILL BE BORDERLINE SUFFICIENT FOR SUPERCELL
STORMS...AND GIVEN PROXIMITY OF STORMS TO DIURNALLY INDUCED WARM
FRONT ALONG WITH 25KTS OF 0-1KM SHEAR...EVEN ISOLATED TORNADOES
APPEAR POSSIBLE IN A FAVORED ZONE ALONG THE NERN QUADRANT OF
NORTHEASTWARD MOVING SURFACE LOW.
THE SURFACE LOW SHOULD MOVE TO NEAR KSUX BY DAYBREAK SUNDAY...WITH
SHOWERS REMAINING LIKELY IN NORTHEAST NEBRASKA AND NORTHWEST IOWA
OVERNIGHT. THE LOW SLOWLY MOVES INTO THE UPPER MISSISSIPPI RIVER
VALLEY THROUGH SUNDAY...WITH SOME THREAT FOR SHOWERS IN OUR
AREA...ESPECIALLY ACROSS NORTHEAST NEBRASKA AND WEST CENTRAL
IOWA...AND LOWER CHANCES AS YOU MOVE FURTHER WEST/SOUTHWEST FROM
THE LOW CENTER.
LOW SHOULD BE SUFFICIENTLY FAR ENOUGH WAY BY SUNDAY EVENING TO END
THE PRECIP...WITH RETURN SOUTHERLY FLOW DEVELOPING AHEAD OF THE
NEXT FAST MOVING COLD FRONT THAT SHOULD MOVE INTO THE REGION ON
MONDAY. MOST OF THE REGION SHOULD REMAIN DRY MONDAY MORNING...BUT
WILL BEGIN TO SPREAD 40 TO 60 PERCENT POPS BACK INTO THE AREA
MONDAY AFTERNOON AND MONDAY NIGHT...WITH BACK EDGE OF PRECIP JUST
EAST OF THE EASTERN CWFA BORDER BY DAYBREAK TUESDAY.
BEYOND THEN...COOLER TEMPERATURES ARE EXPECTED THROUGH THE
REMAINDER OF NEXT WEEK...ALTHOUGH LATEST ECMWF TRENDS ARE NOT AS
COLD AS GFS. TEMPERED FORECAST HIGHS/LOWS JUST A TAD THROUGH MID
WEEK WITH PRECIPITATION REMAINING JUST TO THE NORTH ACROSS SOUTH
DAKOTA AND MINNESOTA.
AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
MVFR CIGS OVER SERN NEB THIS MORNING WILL SPREAD NWD AND ENVELOP THE
REST OF ERN NEB. HOWEVER...AS MAIN UPPER LOW SHIFTS AWAY FROM THE
REGION...SLOT OF DRIER AIR IS EXPECTED TO MIGRATE IN FROM THE SW AND
SHOULD SCOUR OUT ANY MVFR CIGS AT TAF SITES BY EARLY AFTN. CURRENT
TAFS HAVE PROB30 GROUPS IN ANTICIPATION OF POSSIBLE -TSRA DEVELOPMENT
GENERALLY BTWN 23/21Z-24/02Z. MODELS CONTINUE TO INDICATE ENVIRONMENT
WILL BE UNSTABLE AT THAT TIME...AND WILL PROBABLY KEEP PROB30 GROUPS
IN PLACE AT ALL SITES AT NEXT ISSUANCE.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
ZAPOTOCNY