Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 220453
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1153 PM CDT THU APR 21 2016

.SHORT TERM...(TONIGHT THROUGH SUNDAY)
ISSUED AT 334 PM CDT THU APR 21 2016

AFTER LINGERING SHOWERS THIS EVENING...MAIN FOCUS THIS FORECAST IS
WARMING TEMPERATURES INTO THE WEEKEND AND THE CHANCE FOR CONVECTION
SUNDAY.

UPPER LOW WAS MAKING STEADY PROGRESS TO THE EAST AS IT SPUN ACROSS
THE IOWA AND MISSOURI BORDER DURING THE AFTERNOON. BAND OF SHOWERS
IN VORTICITY CHANNEL ON BACK SIDE OF LOW WAS STILL TRIGGERING A FEW
SHOWERS IN FAR EASTERN NEBRASKA AND SOUTHWEST IOWA. WITH LOSS OF
DAYTIME HEATING AND SYSTEM PROGRESSION TO THE EAST...EXPECT ANY
SHOWERS TO BE ENDING FOR THE MOST PART BY SUNSET.

THEN SURFACE HIGH PRESSURE WILL SETTLE INTO THE REGION LATER TONIGHT
AND FRIDAY...BRINGING CLEARING SKIES AND LIGHT WINDS. LOWS TONIGHT
SHOULD DROP INTO THE LOWER AND MIDDLE 40S...WITH SOME UPPER 30S
NORTH. SUNSHINE AND A LATE RETURN TO SOUTHERLY FLOW SHOULD BOOST
HIGHS FRIDAY AFTERNOON INTO THE 60S.

MID LEVEL RIDGING WILL THEN MOVE OVER THE PLAINS FOR SATURDAY...WITH
WARMING AT ALL LEVELS EXPECTED THEN. 850 TEMPS RISE FROM NEAR 5C
FRIDAY MORNING INTO THE 15-20C RANGE BY SATURDAY AFTERNOON.
FAVORABLE SOUTHWEST FLOW JUST OFF THE SURFACE SUGGESTS SOME
DOWNSLOPE COMPONENT MAY HELP WARMING IN THE AFTERNOON...SO HIGHS
WELL INTO THE 70S IF NOT LOWER 80S LOOK ON TRACK.

FOR SATURDAY NIGHT AND SUNDAY...UPPER LOW IN THE CENTRAL/NORTHERN
ROCKIES WILL BEGIN PUSHING TO THE EAST...AND IS FORECAST INTO SOUTH
DAKOTA BY SUNDAY AFTERNOON. STRONG MID LEVEL WARM ADVECTION PATTERN
IS NOTED SATURDAY NIGHT AS SOUTHWESTERLY LOW LEVEL JET KICKS UP TO
MORE THAN 50KT OVER OUR AREA. MOISTURE PROFILES MAY NOT BE ROBUST BY
THIS TIME...BUT STILL ENOUGH FORCING TO SPARK AN ELEVATED
THUNDERSTORM AFTER MIDNIGHT. SOME OF THAT ACTIVITY WILL LIKELY
LINGER INTO THE MORNING BEFORE MOVING OFF TO THE
NORTHEAST...ALLOWING ATMOSPHERE TO RECOVER FOR POTENTIAL AFTERNOON
ACTIVITY.  WEAK FRONTAL BOUNDARY IS FORECAST INTO SOUTHEAST NEBRASKA
AND SOUTHWEST IOWA DURING THE AFTERNOON...BUT LOW LEVEL CONVERGENCE
WILL BE AT A MINIMUM WITH WINDS FAVORING A GENERAL SOUTHWEST
DIRECTION ON BOTH SIDES OF THE FRONT. MOISTURE WILL HAVE A LITTLE
LONGER TO RETURN TO THE AREA HOWEVER...AND BEST THETA-E PLUME WILL
LIE ALONG FRONTAL ZONE. MEANWHILE...COOLING MID LEVELS UNDER WARMING
SURFACE TEMPERATURES WELL INTO THE 70S SUGGESTS MODERATE INSTABILITY
IS POSSIBLE. BULK SHEAR NEAR 40KT PARALLELING THE FRONT POINTS TO
POTENTIAL FOR STRONG WINDS IN ANY STORMS THAT CAN GET GOING.

.LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY)
ISSUED AT 334 PM CDT THU APR 21 2016

PERHAPS A BETTER POTENTIAL FOR SEVERE STORMS MAY BE SETTING UP FOR
THE MIDDLE OF NEXT WEEK...THOUGH BEST CHANCES LOOK TO REMAIN TO OUR
SOUTH. UPPER LOW ON SUNDAY IS FORECAST TO MOVE THROUGH THE NORTHERN
PLAINS BY MONDAY...TAKING LINGERING RAIN/THUNDER CHANCES WITH IT.
NEXT UPPER LOW WILL BE FORMING IN THE WESTERN STATES MONDAY NIGHT
BEFORE EJECTING INTO THE PLAINS LATER TUESDAY...AND MOVING OVER
EASTERN NEBRASKA ON WEDNESDAY. BOTH GFS AND ECMWF OPERATIONAL MODELS
SHOW THIS SCENARIO. STRONGEST MID LEVEL FLOW WILL POINT TO KANSAS
AND OKLAHOMA WHERE SURFACE LOW FORMATION IS MOST LIKELY...PUTTING
WARM FRONT CLOSE TO I-70 TUESDAY NIGHT. GFS SUGGESTS FRONT WILL
MOVE NORTH INTO OUR AREA ON WEDNESDAY...BUT ECMWF PUSHES FRONTAL
POSITION FARTHER TO OUR EAST. STILL THE CHANCE FOR RAIN AND
THUNDERSTORMS IS RELATIVELY HIGH GIVEN EITHER SCENARIO...SO WILL
MAINTAIN LIKELY POPS THEN. OTHERWISE PROGRESSIVE NATURE OF THIS
SYSTEM WILL LEAD TO A DRY FORECAST FOR THURSDAY.

&&

.AVIATION...(06Z TAFS FOR KOMA...KLNK...KOFK THROUGH 06Z SATURDAY)
ISSUED AT 1141 PM CDT THU APR 21 2016

CURRENT LOOP OF IR SATELLITE IMAGERY INDICATES A NARROW AXIS OF
MVFR CIGS DEVELOPING FROM NWRN IA INTO E-CNTRL NEB /AT KOMA AND
JUST N OF KLNK/. LATEST SHORT-TERM MODEL GUIDANCE SUGGESTS THAT
THESE CLOUDS WILL LINGER OVERNIGHT ACROSS PORTIONS OF WRN IA WITH
KOMA REMAINING ON THE IMMEDIATE EDGE OF PREVAILING MVFR
CONDITIONS. GIVEN THE UNCERTAINTY...HAVE OPTED TO INCLUDE A TEMPO
GROUP FOR MVFR CIGS THROUGH 08Z WITH PREVAILING VFR CONDITIONS
THEREAFTER. THIS WILL HAVE TO BE WATCHED HOWEVER. AT KLNK...A
BRIEF PERIOD OF MVFR CIGS COULD OCCUR BETWEEN 06-07Z...BUT IN
GENERAL...VFR CONDITIONS ARE ANTICIPATED THROUGH THE MAJORITY OF
THE FORECAST PERIOD. VFR CONDITIONS WILL PREVAIL AT KOFK WITH
WINDS BECOMING SELY BY FRIDAY AFTERNOON OR EVENING.

&&

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

$$

SHORT TERM...DERGAN
LONG TERM...DERGAN
AVIATION...MEAD



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