Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 230820
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
320 AM CDT SAT MAY 23 2015

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 311 AM CDT SAT MAY 23 2015

...MAIN CHALLENGE IS TIMING THE MORE LIKELY PERIODS OF RAIN...

THE FORECAST AREA WILL REMAIN IN AN ACTIVE PATTERN THROUGH MONDAY
NIGHT AS A LARGE UPPER LOW CONTINUES TO SPIN OVER THE ROCKIES.
EARLY MORNING WATER VAPOR LOOP WAS TELLING...IMPRESSIVE AMOUNT OF
SUBTROPICAL MOISTURE WAS BEING PULLED INTO THE PLAINS AND ROCKIES
REGIONS AS SLOW MOVING UPPER LOW CHURNS NEAR FOUR CORNERS. BLENDED
TOTAL PRECIPITABLE WATER PRODUCT SHOWED MOST OF THE PLAINS AND
ROCKIES OVER 100 PERCENT OF NORMAL AT 06Z. LARGE SURFACE HIGH
PRESSURE MOVED FROM EASTERN NEBRASKA TO PENNSYLVANIA IN THE PAST
24 HOURS...WITH WEAK LEE SIDE CYCLOGENESIS TAKING SHAPE ALONG THE
FRONT RANGE. SOUTHERLY LOW LEVEL FLOW HAS BECOME ESTABLISHED OVER
THE PLAINS EARLY THIS MORNING...ALBEIT WEAK. MOISTURE RETURN HAS
BEEN STEADY...WITH SURFACE DEWPOINTS IN THE LOW 50S OVER MUCH OF
THE FORECAST AREA AND LOW 60S TO THE SOUTH ALONG THE RED RIVER.

THIS PATTERN WILL BE CONDUCIVE TO THE DEVELOPMENT OF SHOWERS
GIVEN THE INCREASINGLY MOIST PROFILE AND NUMEROUS SOURCES OF
VERTICAL MOTION. THE BIG UPPER LOW TO THE WEST WILL PROVIDE
DIFFLUENT FLOW AT THE JET LEVEL AS IT MEANDERS NORTHEAST THROUGH
MONDAY NIGHT. SHORTWAVES ROTATING AROUND THE LOW WILL PROVIDE
ADDITIONAL LIFT. THIS HAS RESULTED IN A FAIRLY LARGE AREA OF
SHOWERS CURRENTLY OVER SOUTHWEST NEBRASKA INTO COLORADO...BUT THIS
AREA SHOULD MOVE QUITE SLOWLY NORTHEAST. MUCH OF THE FORECAST
REGION SHOULD REMAIN DRY TODAY...WAITING FOR THE SHOWERS TO THE
WEST TO ARRIVE AND TRACK NORTHEAST ACROSS THE REGION. INSTABILITY
IS LIMITED DUE TO THE RELATIVELY COOL AIRMASS...THEREFORE
THUNDERSTORMS ARE NOT EXPECTED TO BE WIDESPREAD WITH THIS RAIN
TODAY.

TONIGHT THE RAIN WILL OVERSPREAD THE AREA AND WILL BE AIDED BY A
30-35 KNOT LOW LEVEL JET AND WEAK ISENTROPIC LIFT. A SLIGHT
INCREASE IN INSTABILITY IS EXPECTED WITH INCREASING LOW LEVEL
MOISTURE. RAIN CHANCES TONIGHT LOOK HIGH...IN THE 70-90 PERCENT
RANGE.

DURING THE DAY ON SUNDAY A WARM FRONT WILL MOVE NORTH THROUGH THE
REGION...HOWEVER MOST MODELS STILL PULL A DRY SLOT NORTH THROUGH
NEBRASKA DURING THE AFTERNOON. THIS WILL LIMIT CONVECTION IN
WESTERN COUNTIES BUT THE WARM FRONT MAY SUSTAIN THE CONVECTION IN
EASTERN COUNTIES. POPS ARE TAPERED FROM SLIGHT CHANCE IN THE WEST
TO LIKELY EAST SUNDAY.

SUNDAY NIGHT INTO MONDAY CONFIDENCE IS LOW WITH THE POP FORECAST.
THE PRIMARY UPPER CIRCULATION IS EXPECTED TO MOVE INTO MINNESOTA
MONDAY...HOWEVER THE AIRMASS WILL REMAIN MOIST AND UNSTABLE WITH
THE POTENTIAL FOR ADDITIONAL SHORTWAVES MOVING THROUGH THE
SOUTHWEST UPPER FLOW. WE CONTINUED THE CHANCE POPS FOR
THUNDERSTORMS IN THE SUNDAY NIGHT - MONDAY NIGHT PERIOD.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 311 AM CDT SAT MAY 23 2015

WE FINALLY HAVE SOME CONFIDENCE IN A DRY PERIOD TUESDAY INTO
WEDNESDAY AS WEAK UPPER RIDGING MOVES IN AND MORE
IMPORTANTLY...SURFACE HIGH PRESSURE BUILDS IN FROM THE NORTH. BUT
THIS IS SHORT LIVED AS YET ANOTHER SOMEWHAT IMPRESSIVE TROF MOVES
THROUGH THE WESTERN US WEDNESDAY NIGHT THROUGH FRIDAY. SURFACE
CYCLOGENESIS AND RETURNING MOISTURE IS CAUSE FOR CHANCE POPS
DURING THE SECOND HALF OF THE UPCOMING WEEK.

&&

.AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1150 PM CDT FRI MAY 22 2015

CEILINGS WILL LIKELY REMAIN IN THE VFR CATEGORY THROUGH 12Z BUT
WILL PROBABLY TREND INTO THE MVFR CATEGORY SATURDAY MORNING. PCPN
IS EXPECTED TO BE SPOTTY UNTIL SATURDAY EVENING WHEN COVERAGE WILL
LIKELY INCREASE WITH SOME RESTRICTION TO VSBY. IFR CEILINGS ARE
POSSIBLE SATURDAY EVENING...MAINLY AT KOFK AND KLNK.

&&

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

$$

SHORT TERM...NIETFELD
LONG TERM...NIETFELD
AVIATION...MILLER



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