Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 290855
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
355 AM CDT MON SEP 29 2014

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 335 AM CDT MON SEP 29 2014

SHORT TERM FORECAST CONCERNS WILL BE SOME PATCHY FOG EARLY...HOW
THE BACKDOOR COLD FRONT WILL AFFECT AREAS IN NORTHEAST NEBRASKA
AND WEST CENTRAL IOWA...THEN TIMING OF THUNDERSTORM CHANCES AND
SEVERE WEATHER POTENTIAL TUESDAY THROUGH MID WEEK WITH SEVERAL
WAVES OF PRECIPITATION.

OUR 00Z OAX SOUNDING HAD INCREASED TO 1.16 INCHES PWAT WITH 656
J/KG CAPE AND LITTLE CIN. WILL CONTINUE TO MONITOR THE RADAR
ECHOES FOR PLACING ISOLATED POPS THIS MORNING...BUT EARLY MORNING
RETURNS HAVE BEEN FROM SOUTHEAST SOUTH DAKOTA INTO NORTHWEST IOWA.
LIGHTNING WAS MOSTLY CONCENTRATED IN CLUSTERS OVER THE BLACKHILLS
AREA INTO THE NEBRASKA PANHANDLE AND OVER PARTS OF WYOMING AND
COLORADO.

THE UPPER AIR MAPS SHOWED A LARGE CLOSED H5 LOW OVER NEVADA...A
RIDGE OVER THE MIDWEST...AND A MORE SHEARED OUT H5 TROF OVER
SOUTHERN CANADA. THERE WAS ABUNDANT H7 MOISTURE FROM THE NORTHERN
PLAINS INTO THE ROCKIES SOUTHWARD TO MEXICO AND SOUTHERN BAJA...TO
WHERE HURRICANE RACHEL IS IN THE EASTERN PACIFIC. H85 MOISTURE OF
12-14DEG C WAS POOLED IN THE VICINITY OF THE H85 FRONT FROM MN
INTO SD.

TODAY...THERE IS SHORTWAVE TROF ENERGY THAT WILL MOVE THROUGH THE
UPPER MISSISSIPPI VALLEY AND THE GREAT LAKES.  MEANWHILE...THE H5
CLOSED LOW WILL TRACK EAST TO MONTANA/WYOMING/COLORADO...WITH THE H5
RIDGE SHARPENING OVER THE PLAINS. THE GREAT LAKES SHORTWAVE WILL
HAVE ENOUGH OF A PUSH TO DRAG THE COLD FRONT NEAR SIOUX FALLS
SOUTHWARD TOWARD SIOUX CITY...MEANWHILE...THE UPSLOPE FLOW IS
INCREASING OVER THE WESTERN PLAINS/LEE OF THE ROCKIES.  THE LOW
LEVEL JET INCREASES TO 25 TO 30KTS EARLY THIS MORNING AND SHOULD
SEE SOME ADDITIONAL SHOWER AND THUNDERSTORM ACTIVITY RESULT
OVERNIGHT. THERE HAS BEEN A TREND FOR THE SHOWERS TO LIFT NORTH
NORTH OF ONEILL...WHILE THE SHOWERS CLOSER TO SIOUX CITY ARE
DRIFTING SOUTHEAST WITH THE CLOUD BEARING WINDS.  THE LLJ WEAKENS
AFTER 12Z TO 15KTS...SO LOOK FOR COVERAGE TO DECREASE. A FEW
STORMS COULD THEN RE- FIRE WITH HEATING DURING THE DAY AND WEAK
CONVERGENCE NEAR THE FRONTAL BOUNDARY. FOR NOW...HAVE KEPT
ISOLATED MENTION FOR SHRA/-TSRA IN FOR A FEW OF OUR NORTHERN
PERIPHERY COUNTIES AND THEN AGAIN IN THE AFTERNOON. WILL NEED TO
WATCH HOW FAR THE MORE EXTENSIVE CLOUDCOVER WILL MOVE SOUTH WITH
THAT BACKDOOR FRONT AS THIS WOULD IMPACT HIGH TEMPERATURES NEAR
THE SD BORDER INTO WEST CENTRAL IOWA. HIGHS TODAY SHOULD MAINLY BE
80 TO 85...HOWEVER MORE EXTENSIVE CLOUDCOVER IN THE NORTH COULD
HOLD TEMPERATURES IN THE 70S.

120M HEIGHT FALLS WILL MOVE INTO THE NEBRASKA PANHANDLE TONIGHT
AND TRACK INTO THE DAKOTAS TUESDAY WITH THE TRACK OF THE H5 LOW.
UPPER LEVEL SUPPORT...COMBINED WITH H7 OMEGA...STEEPENING LAPSE
RATES AND THE EASTWARD PROGRESS OF THE 40KT LOW LEVEL JET AND
DEEP MOISTURE WILL RESULT IN THUNDERSTORMS...SPREADING EASTWARD
OVERNIGHT AND BECOMING MORE WIDESPREAD TUESDAY. INSTABILITY
INCREASES TO AROUND 1500 J/KG AND SHEAR INCREASES TO 35-45KT
ACROSS THE AREA. SOME OF THE STRONGER FORCING QUICKLY LIFTS TO THE
NORTHEAST EARLY AFTERNOON...HOWEVER THERE APPEARS TO BE
ADDITIONAL SUPPORT FOR SEVERE STORMS THROUGH THE AFTERNOON AS THE
FORECAST SOUNDINGS REMAIN FAVORABLE AND SHEAR AND INSTABILITY
INCREASES. THERE WILL BE A NOTICEABLE INCREASE IN THE WINDS TO THE
BREEZY/WINDY CATEGORY TUESDAY.

ADDITIONAL STORMS SHOULD DEVELOP TUESDAY NIGHT FOR THE SOUTHEAST
HALF OF THE FORECAST AREA. WEDNESDAY...ANOTHER WAVE WILL ROTATE
THROUGH THE TROF AND A POSSIBLY A THIRD WAVE THURSDAY. ADDITIONAL
SCATTERED SHOWERS AND THUNDERSTORMS CAN BE EXPECTED WITH EACH
PASSING WAVE. THE HIGHER CHANCES CONTINUE IN THE SOUTHEAST HALF OF
THE FORECAST AREA...WITH LOWER CHANCES IN THE NORTHWEST. HIGHS
TUESDAY AND WEDNESDAY WILL BE IN THE 70S.

.LONG TERM...(THURSDAY NIGHT THROUGH SUNDAY) ISSUED AT 335 AM CDT
MON SEP 29 2014

MAINLY DRY WEATHER FOR THE REST OF THE LONG TERM WITH HIGHS IN THE
60S AND 70S.

&&

.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1135 PM CDT SUN SEP 28 2014

ISOLATED SHOWERS/TSTMS REMAIN POSSIBLE IN MAINLY NERN NEBR TONIGHT
BUT CHANCES STILL APPEARED TO LOW TO MENTION IN KOFK TAF.
OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH 30/06Z WITH MAINLY
MID-LEVEL CLOUDS TONIGHT. A WEAK BOUNDARY...WITH CIGS AROUND OR
BELOW FL010 BEHIND IT...EXTENDED FROM NCNTRL NEBR INTO ERN SD.
THIS FRONT SHOULD RMN TO THE NORTH OF KOFK THROUGH 30/06Z.


&&

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

$$

SHORT TERM...ZAPOTOCNY
LONG TERM...ZAPOTOCNY
AVIATION...CHERMOK



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