Area Forecast Discussion
Issued by NWS Des Moines, IA

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561
FXUS63 KDMX 010845
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
345 AM CDT SUN MAY 1 2016

.SHORT TERM.../TODAY/
ISSUED AT 345 AM CDT SUN MAY 1 2016

ANOTHER VERY MESSY FORECAST FOR TODAY.  THE UPPER LOW WILL SLOWLY
MIGRATE ACROSS THE STATE TODAY.  AHEAD OF THE LOW WE WILL CONTINUE
TO DEAL WITH STRATUS AND FOG ALONG WITH A COLD DRIZZLE.  BANDS OF
PRECIP ACROSS NORTHERN IOWA AND TO THE WEST WILL WRAP AROUND THE LOW
AND BRING SHOWERS...ESPECIALLY TO SOUTHERN IOWA...AS THE UPPER LOW
MOVES BY.  BY LATE IN THE AFTERNOON...THE WEST SHOULD FINALLY SEE AN
END TO THE SHOWERS BUT STRATUS AND LIKELY SOME DRIZZLE WILL REMAIN.
THE EAST SHOULD SEE SHOWERS THROUGH THE TODAY PERIOD OF THE
FORECAST.  TEMPS WILL AGAIN GO NOWHERE AND I OPTED FOR THE COOL SIDE
OF GUIDANCE OR A COUPLE DEGREES BELOW GUIDANCE SOUTH ONCE AGAIN.

.LONG TERM.../TONIGHT THROUGH SATURDAY/
ISSUED AT 345 AM CDT SUN MAY 1 2016

THE UPPER LOW PASSING ACROSS THE STATE TODAY WILL OPEN UP AND
SHIFT EAST BY THIS EVENING. POSSIBLE A FEW PATCHES OF VERY LIGHT
PRECIPITATION LINGERS INTO THE EARLY EVENING OTHERWISE DRYING
CONDITIONS WILL ARRIVE WITH WEAK HIGH PRESSURE ARRIVING. SOLUTIONS
HAVE COME IN LINE WITH WHAT THE ECMWF HAS BEEN SUGGESTING THE PAST
48 HRS FOR MONDAY. THE UPPER LEVEL SHORT WAVE CURRENTLY OVER
NORTHERN SASKATCHEWAN...WILL MOVE INTO MANITOBA TONIGHT THEN DROP
SOUTH AND IMPACT THE STATE ON MONDAY. THIS SYSTEM WILL FEATURE A
COLD CORE ALOFT WHICH WILL ENHANCE INSTABILITY AS LAPSE RATES
STEEPEN WITH SOME SFC HEATING COMBINED WITH THE COOLING
TEMPERATURES ALOFT. SOME WEAK CAPE DOES DEVELOP HOWEVER
EQUILIBRIUM LEVELS ARE CAPPED AT 15 KFT OR BELOW AND NEAR
-15C...BOTH OF WHICH SHOULD LIMIT AND THUNDER POTENTIAL. HAVE
INCREASED POPS A BIT OVER THE SOUTH. STILL NO POPS ACROSS THE
NORTH HOWEVER STILL THE POTENTIAL THAT PRECIPITATION WILL NEED TO
BE ADDED FURTHER NORTH PENDING TIMING AND PLACEMENT DETAILS.

TUESDAY WILL BE MILD AND DRY WITH THE LOW LEVEL FLOW BECOMING
WESTERLY. HIGH TEMPERATURES WILL BE IN THE UPPER 60S TO LOW 70S
TUESDAY. A CLOSED UPPER LOW WILL DIVE SOUTH INTO THE GREAT LAKES
REGION TUESDAY NIGHT. THIS SYSTEM WILL BRING A NARROW WINDOW OF
FORCING AND A SHALLOW RIBBON OF MOISTURE NEAR 750 MB OVER
NORTHEAST/EASTERN IA. THIS MAY BE ENOUGH FOR A FEW SHOWERS TO
DEVELOP. DRIER AIR WILL QUICKLY FOLLOW BY 06Z WITH PRECIPITATION
CHANCES ENDING. WEDNESDAY WILL BE COOLER AS THE SYSTEM WILL ALSO
DRAG COOLER TEMPERATURES INTO THE STATE. A WARMING TREND WILL
BEGIN THURSDAY AS THE UPPER LEVEL SYSTEM MOVES OVER THE EASTERN
CONUS WHILE ANOTHER LARGE UPPER LOW DEVELOPS OVER THE DESERT
SOUTHWEST. THIS WILL THE DEFAULT RIDGE BETWEEN THE TWO SYSTEMS AND
WARMER AIR TO MOVE EAST TOWARDS THE STATE. HIGH TEMPERATURES BY
NEXT WEEKEND MAY PUSH 80 IN SOME AREAS.

&&

.AVIATION.../FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT/
ISSUED AT 1143 PM CDT SAT APR 30 2016

LOW CLOUDS AND LIGHT SHOWERS WILL PERSIST INTO SUNDAY
AFTERNOON...WITH ASSOCIATED IFR OR LOW MVFR VSBYS/CIGS ESPECIALLY
AT DSM/OTM. THERE SHOULD BE STEADY IMPROVEMENT DURING THE
AFTERNOON AS THE SHOWERS GRADUALLY CLEAR OUT...HOWEVER TOMORROW
NIGHT AS WINDS BECOME LIGHT THERE IS SOME QUESTION AS TO HOW MUCH
FOG/STRATUS MAY REDEVELOP OVER THE AREA AFTER SUNSET. THIS WILL BE
FURTHER ASSESSED FOR SUBSEQUENT TAF ISSUANCES.


&&

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

$$

SHORT TERM...FAB
LONG TERM...DONAVON
AVIATION...LEE



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