Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 141706
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1206 PM CDT SUN SEP 14 2014

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 326 AM CDT SUN SEP 14 2014

CHANCE FOR THUNDERSTORMS TONIGHT REMAINS THE PRIMARY FORECAST
CONCERN.

MEAN MID LEVEL TROUGH WAS OVER THE NORTHERN PLAINS THIS
MORNING...WITH JET EXTENDING FROM ALBERTA INTO SOUTH DAKOTA AND
MINNESOTA AND ON TOWARD THE GREAT LAKES. SHORTWAVE WAS NOTED IN
CENTRAL ALBERTA...AND IS FORECAST TO DIVE INTO EASTERN SOUTH
DAKOTA OVERNIGHT. FORCING FOR ASCENT WILL COMMENCE AHEAD OF THIS
FEATURE OVER THE PLAINS BEGINNING THIS EVENING...WITH MAXIMUM
FORCING NEAR 09Z BEFORE WAVE SWINGS TO THE EAST MONDAY MORNING.
TWO DISTINCT AREAS OF PRECIPITATION SHOULD RESULT TONIGHT...BOTH
ELEVATED IN NATURE. ONE AREA IS EXPECTED IN SOUTH DAKOTA AND
NORTHEAST NEBRASKA UNDER DIVERGENT UPPER FLOW REGIME NEAR JET
SEGMENT ASSOCIATED WITH VORTICITY MAXIMUM. MAINLY SHOWERS ARE
EXPECTED HERE AS INSTABILITY PROFILES ARE RELATIVELY WEAK. FARTHER
SOUTH...WARM ADVECTION PROCESSES WITH INCREASING LOW LEVEL JET
RIDING OVER SURFACE WARM FRONT IN NORTHERN KANSAS WILL LEAD TO A
MARKED INCREASE IN INSTABILITY AS HIGH THETA-E AIR IS DRIVEN
NORTH. COOLING ALOFT WHERE LOWERING HEIGHTS OVERSPREAD EASTERN
NEBRASKA WILL LEAD TO STEEP LAPSE RATES OVER THE SOUTHERN HALF OF
THE CWA AFTER MIDNIGHT. FORECAST SOUNDINGS SUGGEST UP TO 1500 J/KG
OF ELEVATED CAPE AND NEAR ZERO INHIBITION WILL JUXTAPOSE WITH 40KT
OF SHEAR IN AREAS NEAR AND SOUTH OF A LINCOLN TO RED OAK LINE
OVERNIGHT. WHILE MOISTURE PROFILES ARE NOT IMPRESSIVE...THERE IS
CERTAINLY ENOUGH FOR THE POTENTIAL FOR A FEW STRONG THUNDERSTORMS
WITH HAIL IN THE SOUTHERN HALF OF THE CWA.

INTENSITY OF STORMS WILL FADE WITH TIME LATE TONIGHT AS LOW LEVEL
JET BECOMES MORE WESTERLY AND SHORTWAVE BEGINS MOVING EAST. COULD
SEE LINGERING STORMS IN OUR SOUTHEAST THROUGH THE MORNING BEFORE
MOVING OUT OF OUR AREA MONDAY AFTERNOON. NORTHERLY LOW LEVEL FLOW
SHOULD CLEAR CLOUDS THEN...WITH THERMAL TROUGH SETTLING OVER THE
CWA. SHOULD SEE HIGHS GAINING ONLY ABOUT 10 TO 15 DEGREES FROM
MORNING LOWS.

HIGH PRESSURE WILL SETTLE OVER THE REGION MONDAY NIGHT BUT WILL
QUICKLY SHIFT EAST BY TUESDAY MORNING. THUS ONLY A BRIEF PERIOD OF
DECENT RADIATIONAL COOLING IS EXPECTED BEFORE SOUTHERLY WINDS START
TO KICK IN AGAIN. HAVE LOWS IN THE LOW TO MID 40S TUESDAY MORNING
WITH TEMPS REBOUNDING BACK TOWARD 70 TUESDAY AFTERNOON UNDER PLENTY
OF SUNSHINE.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 326 AM CDT SUN SEP 14 2014

NORTHWEST FLOW ALOFT WILL BEGIN THE LONGER TERM PERIOD...BUT A
SOMEWHAT PROGRESSIVE FLOW PATTERN WILL BRING RIDGING INTO THE PLAINS
BY THURSDAY BEFORE ANOTHER TROUGH MOVES INTO THE REGION BY FRIDAY OR
SATURDAY. A WEAK SHORTWAVE RIDING THROUGH CENTRAL NEBRASKA AND
KANSAS COULD TRIGGER SOME CONVECTION IN OUR SOUTH ON
WEDNESDAY...BUT BETTER CHANCES FOR PRECIPITATION WILL WAIT UNTIL
LONGER WAVE TROUGH APPROACHES LATE IN THE WEEK. WILL HAVE
INCREASING CHANCES FOR THUNDERSTORMS FRIDAY INTO SATURDAY.
TEMPERATURES THROUGH THE WEEK SHOULD AVERAGE THE 70S WITH FEW 80S
LIKELY FRIDAY BEFORE CLOUDS/PRECIP INVADE.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1205 PM CDT SUN SEP 14 2014

AS AN UPPER TROUGH MOVES ACROSS THE DAKOTAS THIS EVENING...A
STRENGTHENING LOW LEVEL JET SHOULD BRING SCATTERED THUNDERSTORMS
TO NEBRASKA BY LATE EVENING OR EARLY TONIGHT. ALTHOUGH TSTMS
CANNOT BE RULED OUT AT KOFK...KEPT MENTION JUST AT KOMA AND KLNK
WHERE CHANCES APPEARED A LITTLE HIGHER. KOFK COULD BE MORE
IMPACTED BY A SECOND PRECIP AREA EXPECTED TO DEVELOP SWD OUT OF SD
AS THE DISTURBANCE MOVES TOWARD SW MN BY MONDAY MORNING. THE
CONVECTION SHOULD SHIFT SE OF TAF SITES MONDAY MORNING AS THE WAVE
CONTINUES SE...BUT A FEW SHOWERS AND MVFR CIGS COULD LINGER.

&&

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

$$

SHORT TERM...DERGAN
LONG TERM...DERGAN
AVIATION...CHERMOK


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