Area Forecast Discussion
Issued by NWS Des Moines, IA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KDMX 021720
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1220 PM CDT WED SEP 2 2015

...UPDATED AVIATION DISCUSSION...

.SHORT TERM /TODAY/...
ISSUED AT 334 AM CDT WED SEP 2 2015

A MID/UPPER LEVEL TROUGH IS SLOWLY CROSSING THE REGION EARLY THIS
MORNING...AND HAS GENERATED A BAND OF SHOWERS AND THUNDERSTORMS
EXTENDING FROM NORTH TO SOUTH ACROSS IOWA. THIS BAND WILL CONTINUE
TO TRACK SLOWLY EASTWARD THROUGH THE MORNING HOURS BEFORE WEAKENING
AND MOVING OUT OF OUR FORECAST AREA. NO REAL IMPACTS ARE ANTICIPATED
AS THE STORMS ARE NON SEVERE AND PROGRESSIVE...LIMITING ANY HEAVY
RAIN POTENTIAL. BEHIND THE UPPER TROUGH/LINE OF STORMS SATELLITE
IMAGERY DEPICTS CLEAR SKIES SPREADING ACROSS WESTERN IOWA AND
FORECAST SOUNDINGS SHOW PROFILES CONDUCIVE TO PRETTY GOOD VERTICAL
MIXING TODAY SO WE SHOULD WARM UP NICELY ONCE AGAIN...PARTICULARLY
GIVEN THAT TEMPERATURES REMAIN IN THE LOW TO MID 70S ACROSS MUCH OF
IOWA AT THIS HOUR. HOWEVER...TEMPERATURES AT THE TOP OF OF THE MIXED
LAYER WILL BE A BIT COOLER TODAY PROVIDING A LOWER CEILING FOR HOW
HIGH TEMPERATURES CAN RISE. GIVEN THE EXPECTED BALANCING OF THESE
FACTORS STUCK WITH HIGHS TODAY VERY CLOSE TO WHAT WAS SEEN
YESTERDAY.

.LONG TERM /TONIGHT THROUGH TUESDAY/...
ISSUED AT 334 AM CDT WED SEP 2 2015

THE UPPER PV ANOMALY MOVING ACROSS IOWA EARLY THIS MORNING WILL
CONTINUE TO SHIFT EAST AND IN CONJUNCTION WITH AN UPPER LOW
SETTLING INTO THE PACIFIC NORTHWEST...WILL HELP FORCE A RIDGE TO
DEVELOP THROUGH THE NATIONS MID SECTION. AS THIS PROCESS OCCURS
TONIGHT...THE MOISTURE AND THETA-E ADVECTION WILL LINGER IN THE
PIVOT REGION OVER NORTHEAST IOWA TO LAKE MICHIGAN AN THIS WILL
KEEP LOW POP CHANCES GOING IN THE MASON CITY TO WAVERLY AREAS INTO
THE EVENING.

THE LOW LEVEL THERMAL PROFILES WILL NOT CHANGE MUCH UNDER THE
BUILDING RIDGE THOUGH INCREASED MIXING AND A SLIGHT BOOST IN 850
MB TEMPERATURES WILL HELP READINGS TO BE NEAR TO SLIGHT WARMER
THAN THE PAST FEW DAYS AND SOME LOCATIONS REACHING THE LOW 90S.
THE GFS SOUNDING PROFILES CONTINUE TO BE MUCH TOO DRY BY THE
AFTERNOON WITH DEWPOINTS DIPPING INTO THE UPPER 50S TO LOWER 60S
AND HAS BEEN LEADING TO HIGHER TEMPERATURES. IRONICALLY THE GFS
RAW TEMPERATURES HAVE BEEN RELATIVELY GOOD FOR THE WRONG REASONS
DUE TO MIXING DRY AIR WITH OTHER GUIDANCE BEING TOO LOW. SATURDAY
WILL REMAIN WARM AND HUMID WITH THESE CONDITIONS LIKELY TO LAST
INTO A GOOD PORTION OF SUNDAY. THE PACIFIC NORTHWEST UPPER LOW
WILL BEGIN TO SHIFT EAST OVER THE WEEKEND AND WILL BRING
INCREASING CHANCES FOR THUNDERSTORMS LATE SUNDAY INTO SUNDAY
NIGHT. THIS SYSTEM WILL HELP FLATTEN THE RIDGE WITH A SWITCH TO A
MORE ZONAL FLOW. ANY SFC BOUNDARY ASSOCIATED WITH THE SYSTEM WILL
HAVE A DIFFICULT TIME DROPPING TOO FAR SOUTH DUE TO THE ZONAL FLOW
BUT AT THIS TIME IT APPEARS THE BOUNDARY SHOULD MAKE IT THROUGH
IOWA AND INTO MISSOURI. THIS WILL BRING COOLER AND LESS HUMID
CONDITIONS TO THE STATE.

&&

.AVIATION...02/18Z
ISSUED AT 1218 PM CDT WED SEP 2 2015

VFR CONDITIONS WILL PREVAIL THROUGH ENTIRE TAF PERIOD WITH MAIN
CONCERN WITH WINDS GUSTING THIS AFTERNOON TO 25 KNOTS. GUSTY WINDS
ANTICIPATED LATE IN THE PERIOD WITH MIXING INCREASING BY 15Z
THURSDAY.

&&

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

&&

$$

SHORT TERM...LEE
LONG TERM...DONAVON
AVIATION...PODRAZIK



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.