Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 182023
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
323 PM CDT MON AUG 18 2014

.SHORT TERM...(TONIGHT THROUGH THURSDAY)
ISSUED AT 315 PM CDT MON AUG 18 2014

FORECAST CHALLENGES FOR THE SHORT TERM WILL BE HOW FAR TO THE
SOUTHWEST CONVECTION WILL BUILD BACK INTO THE FORECAST AREA TONIGHT
AND THEN CONVECTIVE CHANCES FOR TUESDAY AND WEDNESDAY WITH THE
RETURN OF A WARM FRONT.

THE ATMOSPHERE HAS DRIED OUT COMPARED TO YESTERDAY WITH A PWAT OF
ONLY 1.06 INCHES ON THE 12Z OAX SOUNDING...HOWEVER...THE SHORTWAVE
WILL BRING MOISTURE WITH IT. THERE ARE A FEW CLUSTERS OF CELLS
OVER SOUTH DAKOTA AND SOME ENHANCED CU AND ECHOES AROUND ORD.

80M HT FALLS WERE ASSOCIATED WITH THE H5 TROF OVER THE GREAT
LAKES...WITH ANOTHER LOBE OF ENERGY ON THE BACKSIDE OF IT OVER
NORTHERN MN AND NORTH DAKOTA. JET LEVEL AND MID LEVEL SUPPORT IS
MORE FOCUSED OVER WISCONSIN AND THE LOW LEVEL SUPPORT IS MORE OVER
NORTHERN MISSOURI. THE STORM PREDICTION CENTER DOES HAVE THE
SLIGHT RISK FOR SEVERE STORMS ACROSS SOUTHEAST
MINNESOTA...WISCONSIN...AND PARTS OF NORTHEAST AND CENTRAL IOWA.
PARTS OF THIS AREA IS ALSO AT RISK FOR EXCESSIVE RAINFALL.

THE MODELS HAVE HAD A TOUGH TIME WITH THE PRECIP AREAS...SO WILL
FOCUS ON WHERE THE FORCING AND MOISTURE IS EXPECTED.  THE 12Z NAM
DID BACK OFF OF THE PRECIP DEVELOPING WESTWARD...HOWEVER THE 12Z GFS
DOES HAVE STORMS INTO NORTHEAST NEBRASKA THIS AFTERNOON AND PARTS OF
THE MISSOURI RIVER VALLEY AND WESTERN IOWA OVERNIGHT.  THE
OPERATIONAL FORECAST SOUNDINGS DO SHOW INSTABILITY INCREASING TO
AROUND 3000 J/KG THIS AFTERNOON WITH LITTLE OR NO CIN.  WITH
LINGERING MOISTURE...THIS MAY ACCOUNT FOR SOME ISOLATED STORM
DEVELOPMENT. LIFT INCREASES TOWARD 00Z WITH THE COOL FRONT/WIND
SHIFT APPROACHING. SOME POOLING OF MOISTURE OCCURS AHEAD OF THIS
FEATURE. IT SWINGS THROUGH OVERNIGHT...AND MOISTURE AND THETA-E
ADVECTION FURTHER INCREASES AS IT APPROACHES KANSAS AND MISSOURI.
FOR NOW...WILL INCLUDE SOME ISOLATED POPS IN OUR NORTHEAST CWA
TOWARD MAPLETON AND INTO NORTHEAST NEBRASKA AND THEN BRING THEM
SOUTHWARD OVERNIGHT INTO WESTERN IOWA AND THEN FAR SOUTHEAST
NEBRASKA.

TUESDAY SHOULD BE DRY WITH THE SURFACE FRONT IN NORTHEAST NEBRASKA.
THIS FRONT LIFTS NORTH TUESDAY NIGHT SO BEGIN TO INCREASE POPS IN
THE SOUTH...THEN SPREAD NORTHWARD ACROSS THE ENTIRE CWA BY WEDNESDAY
MORNING.  THE LATEST RUNS ARE LIFTING THE FRONT FARTHER NORTH...THUS
HAVE LINGERING PRECIP ONLY IN THE NORTHERN THIRD OF THE COUNTY
WARNING AREA TOWARD SOUTH DAKOTA.  WEDNESDAY AFTERNOON...STRONG
HEATING IS EXPECTED AND THIS SHOULD CAP OFF A LARGE AREA OF THE
FORECAST AREA. THERE IS A WEAKNESS IN THE CAP IN SOUTHWEST
IOWA...AND CONVERGENCE NEAR THE LOW PRESSURE IN THE NORTH CENTRAL
NEBRASKA AREA WHICH COULD TRIGGER STORMS THERE OR IF IT WILL BE
FARTHER NORTH IN SOUTH DAKOTA. THE BEST SHEAR APPEARS TO BE NORTH
OF THE FORECAST AREA...BUT CAN BE WATCHED AS WE GET CLOSER TO
WEDNESDAY.

WEDNESDAY NIGHT INTO THURSDAY...FRONTAL LOCATION WILL PLAY A KEY
ROLE IN PRECIP...SO DO HAVE POPS MENTIONED AND WILL HAVE TO ADJUST
EACH SHIFT ON WHERE THE FRONT IS FORECAST.

ABOVE NORMAL HIGHS IN THE 80S ARE FORECAST FOR TUESDAY WITH 80S AND
90S FOR WEDNESDAY AND THURSDAY.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 315 PM CDT MON AUG 18 2014

THURSDAY NIGHT THROUGH SATURDAY...THERE WILL BE FRONTAL SYSTEM
SOMEWHERE IN THE AREA FROM SOUTH DAKOTA INTO NEBRASKA WITH
PERIODIC RAIN CHANCES IN THE VICINITY OF THE FRONT. DUE TO MODEL
DIFFERENCES...WILL GENERALLY TREND WITH ABOVE NORMAL TEMPERATURES
UNTIL THE FRONT PASSES THROUGH THE FORECAST AREA SUNDAY AND
MONDAY.

&&

.AVIATION...(12Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 610 AM CDT MON AUG 18 2014

VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD WITH ONLY A WIND
SHIFT TO THE NORTHWEST BY 00-03Z.

&&

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

$$

SHORT TERM...ZAPOTOCNY
LONG TERM...ZAPOTOCNY
AVIATION...DEWALD


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