Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 121129
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
629 AM CDT SAT JUL 12 2014

.SYNOPSIS...
ISSUED AT 326 AM CDT SAT JUL 12 2014

COLD FRONT FROM NRN MN INTO SERN WY WILL MOVE THROUGH IA TODAY AND
TONIGHT. SECONDARY COLD FRONT WILL MOVE SOUTH ACROSS THE STATE
ON SUNDAY. COOL HIGH PRESSURE WILL DOMINATE THE THROUGH MUCH OF
THE REST OF THE WEEK.

&&

.SHORT TERM /TODAY/...
ISSUED AT 326 AM CDT SAT JUL 12 2014

MAIN CONCERN FOR TODAY WILL BE PRECIPITATION CHANCES...THROUGH THE
MORNING AND ADDITIONAL CHANCES IN THE AFTERNOON. ONGOING MORNING
PRECIPITATION ACROSS CENTRAL IOWA ALONG RIBBON OF THETA-E ADVECTION
AT NOSE OF LLJ WILL PERSIST THROUGH THE MORNING HOURS...WHILE
GENERALLY LIFTING ENE. ANTICIPATE SOME DIMINISHING INTO
THE EARLY MORNING HOURS...ESPECIALLY IN THE SOUTH AS SYSTEM PUSHES
NORTH. GIVEN EARLY MORNING CONVECTION...HAVE CUT BACK ON
TEMPS...ESPECIALLY IN THE SOUTH...THOUGH WILL STILL BE WARM.

FOCUS FOR PRECIPITATION WILL THEN BECOME WEAL FRONTAL
BOUNDARY IN SD/NE WHICH IS EXPECTED TO BEGIN DROPPING INTO CWA BY
AFTERNOON. HAVE KEPT POPS ACROSS THE NORTH WITH BOUNDARY
APPROACHING...PUSHING SE. THUNDERSTORM DEVELOPMENT IN THE AFTERNOON
ACROSS CENTRAL IOWA MAY LEAD TO SEVERE WEATHER...IF AREA CAN
DESTABILIZE ENOUGH BEHIND MORNING CONVECTION. INSTABILITY
PARAMETERS INCREASE ACROSS THE FAR SE LATE IN THE PERIOD WITH
SUFFICIENT SHEAR...AND SEVERE THUNDERSTORMS WILL BE POSSIBLE. IN
ADDITION...ANY REMNANT OUTFLOW BOUNDARY FROM MORNING CONVECTION MAY
ALSO BE THE FOCUS FOR AFTERNOON/LATE AFTERNOON CONVECTION...AND HAVE
THEREFORE KEPT POPS SLIGHTLY FURTHER SOUTH...AWAY FROM BOUNDARY.
THIS WILL ALSO BE IN BETTER DYNAMICS...INCREASING CHANCES FOR SEVERE
THUNDERSTORMS. LASTLY...PWAT VALUES LATE IN PERIOD WILL INCREASE TO
NEAR 2 INCHES...WHICH MAY ALLOW FOR HEAVY RAIN IN THUNDERSTORMS.

.LONG TERM /TONIGHT THROUGH FRIDAY/...
ISSUED AT 326 AM CDT SAT JUL 12 2014

EXPECT TO SEE ROBUST THUNDERSTORM DEVELOPMENT AS THE COLD FRONT
MOVE SOUTHEAST ACROSS THE STATE THIS EVENING. PWAT VALUES ARE
ABOVE 2 INCHES ALONG THE FRONT. THERE IS A GOOD CHANCE FOR STRONG
TO SEVERE THUNDERSTORMS WITH THE FRONTAL PASSAGE...ESPECIALLY
DURING THE FIRST FEW HOURS AFTER DEVELOPMENT. SEVERE THREAT WILL
MOVE OUT OF THE STATE BY LATER THIS EVENING AS CONVECTION BECOMES
COOL POOL DRIVEN AND SLIDES QUICKLY SOUTH AND EAST. SUNDAY WILL
BE DRIER...THOUGH THERE SECONDARY COLD FRONT IS LIKELY TO PRODUCE
ISOLATED SHOWERS AND THUNDERSTORMS AS IT MOVES THROUGH THE STATE
DURING PEAK HEATING. MUCH COOLER WEATHER IS ON TAP FOR THE MIDDLE
PART OF THE WEEK AS COOL HIGH PRESSURE BUILDS INTO THE CENTRAL
U.S. TEMPERATURES WILL FLIRT WITH RECORD LOWS FOR MID JUL FOR BUT
AND WED. A SLOW MODERATION IS EXPECTED AFTER THAT WITH DRY
CONDITIONS EXPECTED AT LEAST INTO SATURDAY.

&&

.AVIATION...12/12Z
ISSUED AT 624 AM CDT SAT JUL 12 2014

EARLY PERIOD SHRA WILL CONTINUE TO BRING MVFR VISIBILITIES TO
NORTHERN SITE KMCW/KALO FOR BEGINNING OF PERIOD...AND SHRA MAY
PERSIST THROUGH MUCH OF THE DAY AT KMCW...THOUGH CONDITIONS WILL
IMPROVE TO LOW VFR. WINDS WILL BE VARIABLE THROUGHOUT THE
DAY...BEFORE BOUNDARY PUSHES SOUTH WITH WINDS SHIFTING TO THE
NORTH TO NORTHEAST BEHIND BOUNDARY. BOUNDARY WILL BRING ADDITIONAL
CHANCES FOR TSRA TO SITES LATE IN THE AFTERNOON THROUGH 06Z. HAVE
INCLUDED VCTS MENTION ATTM. MAY SEE ADDITIONAL BR/FG AT SITES AT
END OF PERIOD...WITH AMPLE LOW LEVEL MOISTURE AT SITES WHICH SEE
ADDITIONAL PRECIPITATION TODAY...BUT HAVE LEFT MENTION OUT ATTM
WITH UNCERTAINTIES IN AFTERNOON/EVENING PRECIPITATION.

&&

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

$$

SYNOPSIS...MS JUL 14
SHORT TERM...AWB
LONG TERM...MS JUL 14
AVIATION...AWB


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