Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 192358
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
658 PM CDT TUE MAY 19 2015

.SHORT TERM...(TONIGHT THROUGH FRIDAY)
ISSUED AT 434 PM CDT TUE MAY 19 2015

UPPER LEVEL LOW PRESSURE PUSHING ACROSS COLORADO...BUT THE LARGE
SCALE SPLIT FLOW BECOMING CONFLUENT ACROSS THE NORTHERN PLAINS
WILL BEGIN PROCESS OF SHEARING SYSTEM EASTWARD OVERNIGHT AND EARLY
WEDNESDAY. ISENTROPIC LIFT WILL CONTINUE TO INCREASE THIS AFTERNOON...
AND AFTER A BATTLE WITH EASTERLY FLOW OF DRIER LOWER TO MID LEVEL
AIR...WILL SEE THE COVERAGE OF RAIN BECOME WIDESPREAD ACROSS THE
AREA STARTING THIS EVENING WEST OF HIGHWAY 81 NORTH TO HIGHWAY 77
SOUTH...AND SPREADING EASTWARD TONIGHT. SOMEWHAT CONCERNED THAT
LONGEVITY OF MORE SIGNIFICANT PRECIP COULD BE IMPACTED BY THE
STRONGER SOUTHERN PLAINS CONVECTION...BUT ENOUGH MOISTURE ALREADY
IN PLACE IN THE MID LEVELS TO ENSURE RAINFALL FOR ALL. HINT OF
ELEVATED INSTABILITY CREEPS NORTHWARD INTO EXTREME SOUTHEASTERN
NEBRASKA...AND WILL KEEP A SMALL THREAT FOR THUNDER IN AREA AROUND
FALLS CITY.

BY LATER WEDNESDAY MORNING...THE MAIN UPPER WAVE FORCING WILL PULL
EAST...LEAVING A WEAKENING MID LEVEL BOUNDARY SAGGING SLOWLY
SOUTHWARD ACROSS THE AREA. INITIALLY LIKELY TO KEEP A HALF DECENT
COVERAGE OF LIGHT PRECIPITATION ACROSS THEN NORTH...BUT AS THE
WAVE PULLS EAST AND MID LEVEL DRIES OUT...SHOULD SEE BETTER RAINS
COME TO AN END. SOME INDICATION THAT LOWER LEVELS COULD TRY TO
BECOME A BIT UNSTABLE AND LEAD TO A FEW SHORT SHOWERS IN THE
WAKE...BUT WITH LARGER SCALE FORCING BECOMING INCREASINGLY HOSTILE
THROUGH THE AFTERNOON...WOULD NOT EXPECT MUCH. MAINLY HIGHS IN THE
50S WITH CLOUDS ABUNDANT.

NORTHERN STREAM BECOMES A BIT MORE DOMINANT INTO THE AREA
WEDNESDAY NIGHT INTO THURSDAY...WITH SURFACE RIDGE SLIPPING SOUTH
ACROSS THE AREA. WILL SEE GENERAL DECREASE IN CLOUDS WEDNESDAY
NIGHT FROM NORTH TO SOUTH...BUT A FEW MORE HIGH CLOUDS MAY SPILL
OVER THE WEAKENED RIDGE THROUGH THE SOUTH LATER IN THE NIGHT.
HAVE HEDGED TEMPS DOWN JUST A TOUCH GIVEN LIGHT WINDS AND CLEAR
SKIES...MAINLY UPPER 30S TO LOWER 40S. A GOOD DOSE OF SUNSHINE
WILL LIKELY YIELD A FEW DIURNAL CLOUDS ON THURSDAY...BUT WILL
MAKE THE MOST OF LIMITED MIXING UNDER RIDGE AXIS TO RESULT IN
MID 60S SOUTH TO NEAR 70 NORTH.

WILL SEE WINDS RETURN TO SOUTHERLY ACROSS THE ENTIRE AREA BY LATER
THURSDAY NIGHT AND FRIDAY AS RIDGE SHIFTS EAST. LEADING WEAK WAVE
ACROSS THE SOUTHWESTERN U.S. WILL EJECT NORTHEAST...LIFTING
THROUGH THE DAY INTO THE MEAN UPPER RIDGING. WILL SEE A PULSE OF
ISENTROPIC ASCENT WORK NORTHWARD ALONG WITH WAVE...AT SAME TIME
SEE THE INITIAL SURGE OF LOWER LEVEL MOISTURE PUSH NORTHWARD
ACROSS THE WESTERN PLAINS. A BIT OF MID LEVEL INSTABILITY EXPECTED
TO FAVOR SHOWERS AND A FEW THUNDERSTORMS ALONG BAND MOVING TOWARD
THE HEART OF THE CWA IN THE AFTERNOON. NOT A GREAT DEAL OF
INSTABILITY OR SHEAR TO CONCERN ABOUT ANY SEVERE THREAT.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 434 PM CDT TUE MAY 19 2015

MESSY PATTERN THROUGH THE LONG HOLIDAY WEEKEND AS UPPER TROUGH
REMAINS ELONGATED FROM THE NORTHERN HIGH PLAINS THROUGH THE
SOUTHERN ROCKIES. VARIOUS IMPULSES WILL WORK NORTHWARD AHEAD OF
THE TROUGH AXIS...WITH PLENTY OF MOISTURE TO WORK WITH...AND
LIKELY SOME PERIODS OF DECENT RAIN CHANCES. QUITE A BIT OF
LOWER LEVEL MOISTURE EXPECTED TO CLOG UP THE SYSTEM IN TERMS OF
GENERATING GREATER DEGREE OF INSTABILITY. FRONTAL BOUNDARY WILL
BE LALLYGAGGING EASTWARD THROUGH THE PERIOD...AND DEPENDING ON
LOCATION...SHEAR AND INSTABILITY PARAMETERS SOMEWHAT
LACKING...BUT WILL NEED TO BE WATCHED ON SUNDAY WITH A BIT
STRONGER MID LEVEL WINDS AND DRYING IN THE MID LEVELS.
DIFFERENCES BY TUESDAY IN LOCATIONS OF WEAKER WAVES IN FLOW...SO
KEPT DRY FOR THE MOMENT.

&&

.AVIATION...(00Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 648 PM CDT TUE MAY 19 2015

REGIONAL RADAR SHOWING WIDESPREAD SHRA BEGINNING TO LIFT INTO ERN
NEB THIS EVENING...AND EXPECT PCPN ACTIVITY/IFR CONDITIONS TO
PREVAIL AT ALL TAF SITE THRU AT LEAST 12Z-14Z WED MORNING.
CONDITIONS IMPROVING THEN TO VFR BY LATE WED AFTN.

&&

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

$$

SHORT TERM...LONG TERM...CHAPMAN
AVIATION...DEE


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