Area Forecast Discussion
Issued by NWS Des Moines, IA

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451
FXUS63 KDMX 301729
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1229 PM CDT SAT APR 30 2016

.SHORT TERM.../TODAY/
ISSUED AT 404 AM CDT SAT APR 30 2016

A FAIRLY STRONG UPPER LOW WILL LIFT OUT OF KANSAS TODAY AND SLOWLY
SHIFT EAST ACROSS IOWA THIS WEEKEND MAKING IT INTO WESTERN IOWA
TONIGHT.  AT THE SURFACE...A LOW WILL LIFT NORTHEAST ACROSS MISSOURI
THEN SHIFT EAST INTO THE OHIO VALLEY.  ALL THE HI-RES MODELS ARE
PRETTY CONSISTENT IN LIFTING A BAND OF RAIN ACROSS THE STATE TODAY
WHICH IS ALREADY UNDERWAY.  I AM A LITTLE CONCERNED THAT QPF MAY
BE A BIT OVERDONE BUT WE HAVE A LONG WAY TO GO BEFORE THIS IS OVER
SO FOR NOW I WENT WITH MODEL CONSENSUS.  WE SHOULD SEE THE HEAVIEST
RAINFALL THIS MORNING THEN WE GET LOSE OUR DEEPER MOISTURE AND
FORCING THIS AFTERNOON SO PRECIP MAY BE MORE DRIZZLE OR VERY LIGHT
SHOWERS.  THE FAR SOUTH DOES GET BRUSHED WITH SOME INSTABILITY SO I
DID KEEP THE MENTION OF ISOLATED THUNDERSTORMS BUT THESE WILL BE
VERY WEAK IF THEY OCCUR AT ALL.  AS FOR TEMPS...WE WILL BE IN WARM
ADVECTION TODAY BUT THIS WILL BE NEGATED BY CLOUDS AND RAINFALL SO I
GENERALLY UNDERCUT GUIDANCE 2 TO 3 DEGREES.

.LONG TERM.../TONIGHT THROUGH FRIDAY/
ISSUED AT 404 AM CDT SAT APR 30 2016

THE UPPER LEVEL SYSTEM WILL BE LIFTING OUT IN TWO SEGMENTS WITH
ONE LIFTING THROUGH TODAY WHILE THE STRONGER PIECE OF ENERGY
REACHING SOUTHEAST NEBRASKA BEFORE STALLING. MID LEVEL DRY AIR
FROM THE FIRST SEGMENT WILL BE OVER CENTRAL AND SOUTHERN IOWA
THROUGH MUCH OF THE NIGHT THOUGH THERE MAY ENOUGH INSTABILITY AND
MOISTURE NEAR THE IA/MO BORDER FOR A FEW SHOWERS TO ISOLATED
THUNDERSTORMS. OTHERWISE...DRIZZLE WILL BE THE MAIN PRECIPITATION
POTENTIAL THROUGH THIS PORTION OF THE STATE. WHILE THE WARM
CONVEYOR MOISTURE ADVECTION WILL HAVE MOVED WELL EAST BY THIS
EVENING...A WRAP AROUND WIND WILL REACH BACK INTO NORTHERN IOWA
AND WILL KEEP RAIN/SHOWER CHANCES IN PLACE.

THE SOUTHEAST NEBRASKA ENERGY WILL BEGIN TO MOVE EAST LATE TONIGHT
THROUGH SUNDAY MORNING. THIS WILL BRING INCREASING KINEMATIC
FORCING ACROSS THE STATE AND RENEWED CHANCES FOR SHOWERS. THE
CLOUDS AND RAIN WILL KEEP TEMPERATURES BELOW SEASONAL VALUES AGAIN
SUNDAY OVER THE EAST. HIGH PRESSURE WILL BE APPROACHING FROM THE
NORTHWEST BY LATE SUNDAY AND WILL USHER IN DRIER AIR TO THE NORTH
AND WEST SO SOME SUN IS POSSIBLE BY THE AFTERNOON. PROFILES WILL
BE FAVORABLE FOR A SHALLOW CUMULUS FIELD TO DEVELOP WITH ANY
SURFACE HEATING AND WOULD LIMIT WARMING POTENTIAL.

AN UPPER RIDGE WILL BE BUILDING TO THE WEST BY SUNDAY INTO MONDAY
AND WILL LEAVE IOWA UNDER NW FLOW. THE ECMWF REMAINS MOST
PROGRESSIVE WITH AN UPPER LEVEL SYSTEM DIVING SOUTH AND FURTHER
WEST IN THIS FLOW THOUGH THE NAM IS TRENDING TOWARDS THIS SOLUTION
AS WELL. SHOULD NOT BE AN BIG IMPACT TO THE STATE BUT MAY BRING
MORE CLOUDS AND KEEP TEMPERATURES COOLER FOR MONDAY. THE REMAINDER
OF THE EXTENDED IS MOSTLY STATUS QUO. TEMPERATURES WILL BE WARMER
BUT NORTHWEST FLOW WILL PERSIST UNTIL A LARGE UPPER LOW EXITS THE
GREAT LAKES REGION AND MOVES TO THE EAST. THIS WILL ALLOW THE
WESTERN RIDGE TO MOVE EAST AND BRING WARMER CONDITIONS. THE
EXTENDED WILL BE MOSTLY DRY WITH AN OUTSIDE CHANCE FOR LIGHT
PRECIPITATION CLIPPING EASTERN IOWA TUESDAY NIGHT AND WEDNESDAY.

&&

.AVIATION.../FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON/
ISSUED AT 1229 PM CDT SAT APR 30 2016

LOW STRATUS TO REMAIN IN PLACE THROUGH THE FORECAST PERIOD. VSBYS
TO LIKELY STAY IN THE MVFR RANGE MUCH OF THE TIME AS WELL.
EXPECTED TO SEE SOME BREAKS IN THE RAIN THIS AFTERNOON INTO THIS
EVENING...BEFORE MORE WIDESPREAD CHANCES RETURN INTO SUNDAY
MORNING. EASTERLY WINDS TO DIMINISH INTO THIS EVENING AND SHIFT
AROUND MORE TO THE NORTH TO NORTHEAST.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...FAB
LONG TERM...DONAVON
AVIATION...BEERENDS



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