Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 240926
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
426 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...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1056 PM CDT SAT MAY 23 2015

MVFR/IFR/LIFR CONDITIONS WILL CONTINUE OVERNIGHT WITH PERIODS OF
DRIZZLE/LIGHT RAIN AND FOG THROUGH SUNDAY MORNING. POTENTIAL FOR
ADDITIONAL SHOWERS AND ISOLATED THUNDERSTORMS SUNDAY AFTERNOON AND
SUNDAY EVENING.FOR NOW INCLUDED LATE IN THE AFTERNOON/EVENING AT
KOMA WITH INCREASING 45KT LOW LEVEL JET AND CONTINUED FAVORABLE
MOISTURE TRANSPORT AND CONTINUED LIFT.

&&

.HYDROLOGY...
ISSUED AT 422 AM CDT SUN MAY 24 2015

ALTHOUGH THIS IS A RELATIVELY MOIST PATTERN...THE EXPECTED
RAINFALL AMOUNTS ARE ON THE LIGHT SIDE...GENERALLY UNDER 1 INCH
ACROSS THE AREA. THERE CERTAINLY COULD BE ISOLATED POCKETS OF
HEAVIER RAIN WITH ANY THUNDERSTORMS GIVEN THE AMOUNT OF
MOISTURE...BUT WE DO NOT EXPECT WIDESPREAD HEAVY RAIN.

MOST RIVERS AND STREAMS HAVE BEEN FALLING OVER THE PAST FEW DAYS
AND THE EXPECTED RUNOFF THROUGH MONDAY NIGHT IS NOT PREDICTED TO
CAUSE ANY SIGNIFICANT RISES. THIS WILL BE MONITORED CLOSELY OVER
THE NEXT FEW DAYS AS MORE PRECISE RAINFALL RATES...DURATIONS...
AND AMOUNTS ARE DETERMINED.

&&

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

$$

SHORT TERM...NIETFELD
LONG TERM...NIETFELD
AVIATION...ZAPOTOCNY
HYDROLOGY...NIETFELD


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