Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 241217
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
717 AM CDT SUN MAY 24 2015

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 422 AM CDT SUN MAY 24 2015

...TIMING PERIODS OF RAIN AND POTENTIAL FOR THUNDER ARE THE MAIN
CHALLENGES...

THE PLAINS HAVE NOT SEEN THIS WET AND ACTIVE OF A WEATHER PATTERN
IN A LONG TIME. THE EARLY MORNING WATER VAPOR LOOP CONTINUES TO
SHOW AN IMPRESSIVELY LARGE UPPER LOW SPINNING OVER WESTERN
COLORADO WITH NUMEROUS SHORTWAVES ROTATING AROUND IT. FOR SEVERAL
DAYS THE UPPER LOW HAS PULLED SUBTROPICAL MOISTURE NORTH AND BACK
TO THE NORTHWEST AROUND THE LOW. THE RESULT HAS BEEN THE RECORD
FLOODING IN THE SOUTHERN PLAINS.

IN NEBRASKA AND IOWA...AREA 00Z RAOBS SHOWED A SATURATED AIRMASS
THROUGH MUCH OF THE TROPOSPHERE...WITH OAX AND TOP PW VALUES ABOVE
THE 90TH PERCENTILE OF CLIMATOLOGICAL VALUES FOR THE DAY. AIRMASS
HAS TROPICAL CHARACTERISTICS. ANY AMOUNT OF VERTICAL MOTION IS
ABLE TO GENERATE DRIZZLE OR LIGHT RAIN THIS MORNING. THUS HAVE
KEPT POPS HIGH DURING THE MORNING...WITH SOME DECREASE THIS
AFTERNOON PARTLY DUE TO A SLIGHT DRYING OF THE BOUNDARY LAYER FROM
DAYTIME HEATING. RAIN AMOUNTS THIS MORNING SHOULD BE LIGHT DUE
TO THE NON CONVECTIVE NATURE OF THE PRECIPITATION. THUNDER IS NOT
EXPECTED THIS MORNING DUE TO THE RATHER STABLE AIRMASS.

FOR THIS AFTERNOON...WE NOW EXPECT THE WARM FRONT THAT WAS
CURRENTLY ANALYZED OVER EASTERN KANSAS TO DRIFT NORTH INTO
SOUTHEAST NEBRASKA/SOUTHWEST IOWA BY SUNSET...PERHAPS AS FAR NORTH
AS INTERSTATE 80. THIS SCENARIO IS MUCH DIFFERENT THAT THE NWP
SOLUTIONS OF THE PAST FEW DAYS. GIVEN THE MOISTURE IN PLACE...ANY
LIFT FROM THE WARM FRONT AS WELL AS UPPER LEVEL SUPPORT WILL
CONTINUE TO PRODUCE RAIN. A FEW HUNDRED J/KG OF CAPE MAY BE
PRESENT THIS AFTERNOON ESPECIALLY OVER THE SOUTHERN HALF OF THE
FORECAST AREA SO ISOLATED THUNDER WAS ADDED TO THE POPS FOR RAIN
SHOWERS THIS AFTERNOON AND EVENING.

IT IS A VERY DIFFICULT POP FORECAST TONIGHT INTO MONDAY NIGHT DUE
TO THE COMPLEXITY OF THE PATTERN...THE WIDELY VARYING MODEL
SOLUTIONS... AND POOR PERFORMANCE OF THE MODEL IN THIS PATTERN FOR
THE PAST FEW DAYS. NONETHELESS...WE HAVE STILL MAINTAINED A CHANCE
OR HIGHER POP TONIGHT INTO MONDAY NIGHT DUE TO THE MOISTURE IN
PLACE AND THE CONTINUATION OF SHORTWAVES MOVING THROUGH THE UPPER
FLOW. TONIGHT THERE ARE SOME FACTORS THAT ARE VERY SUPPORTIVE OF
RAIN ESPECIALLY THE WARM FRONT AND ANOTHER DISTINCT WAVE MOVING UP
THROUGH KANSAS...SO POPS ARE AT OR ABOVE 80 PERCENT FOR SOME
HOURS. AGAIN...LITTLE THUNDER EXPECTED TONIGHT.

BY MONDAY THE MAIN UPPER CIRCULATION SHOULD MOVE NORTHEAST OF THE
AREA BUT MORE SHORTWAVE ENERGY WILL ROTATE THROUGH THE FLOW. POPS
GRADUALLY TREND FROM CHANCE TO 10-15 PERCENT MONDAY THROUGH
TUESDAY RESPECTIVELY.

.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 422 AM CDT SUN MAY 24 2015

TUESDAY NIGHT AND WEDNESDAY THE AREA SHOULD FINALLY BE DOMINATED
BY A SHORT-LIVED UPPER RIDGE AND SURFACE HIGH PRESSURE. DRY AND
MILD WITH WELCOMED SUNSHINE IS FORECAST FOR WEDNESDAY.

BY THURSDAY THE NEXT WESTERN US UPPER TROF MOVES INTO THE GREAT
BASIN AREA WITH A DEEPENING SURFACE LOW OVER THE HIGH PLAINS AND
MORE RETURN FLOW. THEREFORE RAIN CHANCES RETURN FOR THE END OF THE
WEEK.

&&

.AVIATION...(12Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 649 AM CDT SUN MAY 24 2015

MVFR AND IFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH MUCH OF
THE DAY AS UPPER LEVEL SHORT WAVE TROUGH LIFTS NORTHEASTWARD AND
CONTINUES TO BRING RAIN AND LOW CLOUDS TO EASTERN NEBRASKA AND
WESTERN IOWA. CEILINGS AND VISIBILITIES MAY BECOME VFR AT KLNK
AFTER 06Z. IFR AND FOG IS EXPECTED AFTER 08Z AT KOFK.

&&

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

$$

SHORT TERM...NIETFELD
LONG TERM...NIETFELD
AVIATION...SMITH



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