Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 210835
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
335 AM CDT THU MAY 21 2015

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 330 AM CDT THU MAY 21 2015

THE CHANCE FOR STORMS FRIDAY INTO SATURDAY REMAINS THE PRIMARY
FORECAST CHALLENGE FOR THE SHORT TERM PERIOD.

MID LEVEL SHORTWAVE TROUGH EXTENDING FROM THE GREAT LAKES INTO SOUTH
DAKOTA WAS DROPPING SOUTHEAST THIS MORNING...AND WILL EXIT OUR AREA
EARLY IN THE DAY. IN ITS WAKE...SHORTWAVE RIDGING IS FORECAST TO
MOVE OVER MID AMERICA LATER TODAY AND TONIGHT...AHEAD OF A MORE
SIGNIFICANT SHORTWAVE EJECTING INTO THE PLAINS FRIDAY INTO FRIDAY
NIGHT. AT THE SURFACE...HIGH PRESSURE WAS RIDGING IN FROM THE HIGH
PLAINS OF SOUTH DAKOTA INTO EASTERN NEBRASKA...AND WILL DRIFT
SOUTHEAST WITH TIME TODAY. THE HIGH WAS HELPING TO CLEAR SKIES
OVER EASTERN NEBRASKA AND SOUTHWEST IOWA...AND WITH SOUTHEAST
MOVEMENT...EXPECT ESSENTIALLY SUNNY SKIES TO PREVAIL TODAY WITH
NORTHWEST WINDS. HIGHS SHOULD CLIMB WELL INTO THE 60S IF NOT LOW
70S ACROSS OUR AREA.

MID LEVEL CLOUD COVER IS EXPECTED TO COMMENCE LATER TONIGHT AHEAD OF
EJECTING SHORTWAVE. FORECAST SOUNDINGS SHOW A DRY ATMOSPHERE WILL
GRADUALLY MOISTEN TOP-DOWN FROM SOUTHWEST TO NORTHEAST ACROSS THE
CWA ON FRIDAY. HOWEVER FORCING FOR PRECIPITATION WILL FOLLOW
SHORTWAVE THROUGH WESTERN NEBRASKA NORTH INTO SOUTH DAKOTA...AND
WITH A MID LEVEL JET SEGMENT PUNCHING THROUGH KANSAS. INSTABILITY IS
NON-EXISTENT AS WELL. SO ASIDE FROM OUR WESTERN AND SOUTHERN CWA
WHERE PROXIMITY TO UPPER SUPPORT PLAYS A ROLE...HAVING A HARD
TIME SEEING WHY ANY SIGNIFICANT PRECIPITATION WILL FALL BOTH
FRIDAY AND FRIDAY NIGHT. THUS HAVE TRIMMED RAIN CHANCES A BIT
AND SLOWED EASTWARD ADVANCE A TAD.

INSTABILITY WILL BEGIN A SLOW INCREASE DURING THE DAY SATURDAY WHEN
SOUNDINGS SHOW PLENTY OF AVAILABLE MOISTURE...PRECIPITABLE WATER
NEAR 1.25 WHICH IS APPROACHING 150 PERCENT OF NORMAL. WHILE THERE
APPEARS TO BE NO SUBSTANTIAL LOW LEVEL CONVERGENCE OR SIGNIFICANT
MID LEVEL FEATURES MOVING THROUGH...WILL LIKELY SEE ISOLATED SHOWERS
OR STORMS BUBBLE UP SATURDAY AFTERNOON IN THIS MOIST REGIME. SO WILL
MAINTAIN SMALL PRECIP CHANCE THROUGH THE AFTERNOON.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 330 AM CDT THU MAY 21 2015

THUNDERSTORM CHANCES CONTINUE TO BE THE FOCUS FOR THE LONGER TERM
FORECAST AS WELL.

LINGERING ISOLATED SHOWERS OR STORMS FROM SATURDAY AFTERNOON WILL
LIKELY BEGIN TO DISSIPATE SATURDAY EVENING. HOWEVER PRECIP CHANCES
SHOULD INCREASE AGAIN AFTER MIDNIGHT WITH GFS/ECMWF SUGGESTING
SHORTWAVE WILL EJECT THROUGH THE REGION. COULD SEE SOME SIGNIFICANT
RAINS AT THIS TIME GIVEN HIGH PRECIPITABLE WATER AND POTENTIAL FOR
TRAINING AS 850 FLOW PARALLELS MID LEVEL JET AND MID LEVEL DIFFLUENCE
SETS UP JUST TO OUR NORTHEAST. THIS ROUND OF PRECIPITATION SHOULD
LINGER TROUGH SUNDAY MORNING BEFORE SHORTWAVE LIFTS NORTHEAST.
HOWEVER NO SIGNIFICANT ATMOSPHERIC DRYING WILL BE REALIZED AS
SOUTHERLY FLOW CONTINUES AHEAD OF MAIN UPPER TROUGH ADVANCING TOWARD
THE PLAINS. THAT TROUGH WILL SLOWLY DAMPEN AS IT LIFTS NORTHEAST
AND SPITS OUT PIECES OF ENERGY ACROSS THE PLAINS THROUGH TUESDAY.
THEREFORE WE CAN NOT RULE OUT SCATTERED SHOWERS AND THUNDERSTORMS
FROM TIME TO TIME RIGHT INTO THE MIDDLE OF THE WEEK.

&&

.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1159 PM CDT WED MAY 20 2015

VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. SKIES SHOULD
REMAIN CLEAR AS HIGH PRESSURE SETTLES IN OVER THE REGION.
PREVIOUS FORECASTS DID HIGHLIGHT A SMALL CHANCE FOR FOG
DEVELOPMENT. AT THIS POINT IT DOESN`T LOOK LIKE TEMPERATURES WILL
FALL FAR ENOUGH TO WARRANT FOG DEVELOPMENT. THOUGH THERE IS AN
OUTSIDE CHANCE OF MVFR VIS PRIOR TO SUNRISE...THIS CHANCE IS NOT
HIGH ENOUGH TO INCLUDE IT IN THE TAF PERIOD.


&&

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

$$

SHORT TERM...DERGAN
LONG TERM...DERGAN
AVIATION...PEARSON



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