Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 202012
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
312 PM CDT SUN APR 20 2014

.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 254 PM CDT SUN APR 20 2014

MAIN FORECAST CHALLENGE WILL BE POPS TONIGHT/OVERNIGHT AND AGAIN
WEDNESDAY/WEDNESDAY NIGHT.

THE REGION REMAINS IN BETWEEN TWO MID/UPPER LEVEL SYSTEMS. THE FIRST
OF WHICH IS A SHORTWAVE TROUGH MOVING THROUGH NEARLY ZONAL FLOW
ALONG THE INTERNATIONAL/MONTANA BORDER. THE SECOND SYSTEM IS A SHORTWAVE
TROUGH LOCATED OVER THE OKLAHOMA PANHANDLE. 12Z UPPER AIR ANALYSIS
SHOWS 850MB DEWPOINTS IN THE 5-8C RANGE OVER THE CENTRAL PLAINS
AHEAD OF THE SOUTHERN SYSTEM. AT THE SURFACE...THE STATIONARY
BOUNDARY THAT HAD EXTENDED ACROSS NORTHEASTERN NEB HAS WASHED OUT
FOR THE MOST PART. SFC DEWPOINTS RANGE ANYWHERE FROM THE UPPER 40S
TO THE LOWER 50S ACROSS THE FORECAST AREA THIS AFTERNOON.

INSTABILITY CONTINUES TO INCREASE ACROSS NORTHEASTERN KANSAS AS
TEMPERATURES INCREASE INTO THE LOWER 80S. BY 20Z...MUCAPE ACROSS
SOUTHEAST NEB/SOUTHWEST IOWA WAS AROUND 500J/KG. A WEAK IMPULSE
MOVING NORTHEAST OUT OF THE MAIN SOUTHERN SHORTWAVE WILL CONTINUE
TO MOVE INTO NORTHWEST KANSAS PROVIDING SUPPORT FOR SCATTERED
SHOWERS AND THUNDERSTORMS. SHORT RANGE MODELS INCLUDING THE
RAP/HOPWRF/HRRR CONTINUE TO GENERATE CONVECTION LATE THIS
AFTERNOON OVER NORTH CENTRAL KANSAS/SOUTHEAST NEBRASKA AND SPREAD
THIS ACTIVITY NORTHEAST ACROSS EASTERN NEBRASKA AND INTO
SOUTHWESTERN IOWA THIS EVENING. IN ADDITION TO THIS AREA...A
NARROW BAND OF HIGH BASED CONVECTION ALONG THE WASHED OUT FRONTAL
BOUNDARY MAY GENERATE SOME LIGHT RAIN SHOWERS WITH A FEW ISOLATED
RUMBLES OF THUNDER. IN EITHER AREA...BULK SHEAR VALUES WILL
REMAIN QUITE WEAK AND INSTABILITY IS MARGINAL SO NOT ANTICIPATING
ANY SEVERE STORMS.

THE NORTHERN PLAINS SHORTWAVE TROUGH WILL ALLOW A COLD FRONT
CURRENTLY OVER THE WESTERN DAKOTAS TO SLIDE SOUTH INTO THE FORECAST
AREA BY 10-12Z. WILL INCLUDE POPS ALONG THIS BOUNDARY AS IT SLIDES
SOUTH THROUGH THE REGION INTO MONDAY MORNING AND LINGER IN OUR
SOUTHEAST TOWARD 18Z.

SFC HIGH PRESSURE BUILDS OVERHEAD TUESDAY ALONG WITH UPPER LEVEL
RIDGING. LOW LEVEL WARM/MOIST ADVECTION WILL BE UNDERWAY TUESDAY
EVENING AS STRENGTHENING LOW LEVEL JET DRAWS +10C 850MB DEWPOINTS
TOWARD THE AREA. OVERNIGHT CONVECTION LOOKS LIKELY TUE NIGHT/WED
MORNING IN ADVANCE OF APPROACHING WESTERN TROUGH ALONG WITH STRONG
LOW LEVEL JET. A DAYTIME LULL IS LIKELY IN ACTIVITY BUT WEDNESDAY
AFTERNOON/EVENING LOOKS QUITE ACTIVE WITH THE APPROACH OF
DEEPENING UPPER TROUGH AND ASSOCIATED SFC COLD FRONT. SEVERE
WEATHER POTENTIAL HAS BEEN OUTLOOKED BY SPC.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 254 PM CDT SUN APR 20 2014

UPPER TROUGH AXIS WILL SWING THROUGH THE CWA BY THURSDAY MORNING
ALLOWING ACTIVE WEATHER TO SHIFT OFF TO THE EAST. THE MAIN WEATHER
IN THE EXTENDED WILL BE INTO THE WEEKEND AS A STRENGTHENING TROUGH
DIGS ACROSS THE WESTERN CONUS BRINGING ANOTHER ROUND OF ACTIVE
WEATHER TO US LATE IN THE WEEKEND/EARLY NEXT WEEK. TIMING AND
POSITION OF THE LARGE SCALE FEATURES IS UNCERTAIN...BUT IT
CERTAINLY COULD BE ACTIVE FOR A LARGE CHUNK OF THE REGION.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1208 PM CDT SUN APR 20 2014

GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH MONDAY MORNING. WEAK
COLD FRONT ACROSS NORTHEAST NEBRASKA WILL EVENTUALLY MOVE
SOUTHEAST LATER TONIGHT...WITH NORTH WINDS BEHIND THE FRONT
REACHING KOFK BEFORE 12Z AND KOMA/KLNK SLIGHTLY AFTER. A FEW
SHOWERS COULD AFFECT TAF SITES THIS AFTERNOON AND EVENING...WITH
AN ISOLATED THUNDER ALSO POSSIBLE BUT NOT MENTIONED IN TAFS AS
CHANCES ARE RELATIVELY SMALL. BETTER CHANCES FOR SHOWERS OR STORMS
WILL COME WITH THE COLD FRONT OVERNIGHT. STILL LOW LEVEL MOISTURE
IS LIMITED SO GENERALLY VFR CIGS/VSBYS ARE EXPECTED EXCEPT RIGHT
UNDER THE STRONGER STORMS. CLEARING SKIES AND 15 TO 25KT NORTH
WINDS ARE EXPECTED BY 18Z MONDAY.

&&

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

$$

SHORT TERM...KERN
LONG TERM...KERN
AVIATION...DERGAN



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