Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 201736
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1236 PM CDT SAT SEP 20 2014

...UPDATED AVIATION DISCUSSION...

.SHORT TERM /TODAY/...
ISSUED AT 337 AM CDT SAT SEP 20 2014

FIRST COLD FRONT EXTENDING FROM NERN MN INTO NRN IA TO SWRN NEBRASKA
WILL MOVE SOUTHEAST OF THE CWA BY THIS AFTERNOON.  SECONDARY COLD
FRONT FROM NRN MN INTO SWRN SD WILL SWEEP ACROSS TODAY...BUT DON`T
EXPECT MUCH WITH IS AS AIRMASS CONTINUES TO DRY WITH TIME.  HIGHS
TODAY WILL LIKELY BE AT OR A LITTLE ABOVE YESTERDAYS HIGHS WITH THE
COOLER AIR LAGGING.  CURRENT LINE OF CONVECTION ACROSS THE CWA WILL
CONTINUE TO DROP SOUTH WITH THE FIRST COLD FRONT.  THE COMPLEX
HAS BECOME COLD AIR DOMINANT AS THE OUTFLOW HAS PUSHED WELL TO THE
SOUTH OF THE COMPLEX.  WILL CARRY CAT POPS FOR A WHILE WITH THE CORE
OF THE LINE.

.LONG TERM /TONIGHT THROUGH FRIDAY/...
ISSUED AT 337 AM CDT SAT SEP 20 2014

WITH UPPER LOW PASSING JUST NORTHEAST OF THE STATE THIS
EVENING...SOME LINGERING THUNDERSTORMS WILL BE A POSSIBILITY
THROUGH SUNSET WITH ANY PCPN DIMINISHING AS THE EVENING
PROGRESSES. OTHERWISE...COOLER AIRMASS WILL SPREAD INTO THE STATE
OVERNIGHT INTO SUNDAY AS CANADIAN HIGH PRESSURE DROPS INTO THE
REGION. THE HIGH AND ASSOCIATED DRY AIR/SUBSIDENCE WILL ALLOW FOR
TRANQUIL WEATHER FROM SUNDAY INTO TUESDAY WITH BELOW NORMAL
TEMPERATURES.

UPPER LOW CURRENTLY OFF THE CALIFORNIA COAST WILL MOVE EASTWARD
THROUGH THE EARLY PART OF NEXT WEEK AND IS EXPECTED TO REACH THE
HIGH PLAINS BY TUESDAY. INCREASING WARM ADVECTION AND THETA-E
ADVECTION WILL LEAD TO THE DEVELOPMENT OF SHOWERS AND SOME STORMS
ACROSS THE PLAINS AND INTO THE MISSOURI RIVER VALLEY ON TUESDAY.
THE FORCING AND MOISTURE ASSOCIATED WITH THIS UPPER LOW WILL MOVE
VERY GRADUALLY INTO THE STATE TUESDAY NIGHT INTO WEDNESDAY WITH
LIGHT TO MODERATE PCPN. INSTABILITY WILL REMAIN LIMITED AND HAVE
ONLY CONTINUED A MENTION FOR ISOLATED THUNDER AS BEST INSTABILITY
AXIS REMAINS TO THE WEST AND SOUTH. FORCING AND ASSOCIATED LIFT
WILL SLOWLY DIMINISH WITH THIS SYSTEM AS IT MEANDERS UNDERNEATH A
BUILDING RIDGE ACROSS THE CENTRAL US. TEMPERATURES LIKELY TO
REMAIN BELOW NORMAL INTO THE MIDDLE OF THE WEEK WITH MORE
EXTENSIVE CLOUDINESS AND ONGOING THREAT OF PRECIPITATION. DRIER
WEATHER IS EXPECTED TOWARD THE END OF THE FORECAST PERIOD AS LIFT
SUBSIDES AND UPPER RIDGING CONTINUES TO BUILD.

&&

.AVIATION...20/18Z
ISSUED AT 1235 PM CDT SAT SEP 20 2014

ANOTHER SHORTWAVE LOOKS TO CLIP NORTHERN IOWA THIS EVENING AND MAY
BRING SOME THUNDERSTORMS ACROSS MCW/ALO AREA B/T 00Z TO 04Z
TONIGHT. HENCE...HAVE VCTS MENTIONED ATTM. OTHERWISE...VFR
CONDITIONS WILL PREVAIL WITH MIXING INCREASING LATE SUNDAY
MORNING.

&&

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

&&

$$

SHORT TERM...MS SEP 14
LONG TERM...COGIL
AVIATION...PODRAZIK



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