Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 271742
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1242 PM CDT SAT SEP 27 2014

.SHORT TERM /TODAY/...
ISSUED AT 324 AM CDT SAT SEP 27 2014

CLOSED UPPER LOW REMAINS OVER IOWA AND WILL THROUGH TODAY.  TWO
AREAS OF CONVECTION DEVELOPED OVER SOUTHERN IA WITH ISOLATED TWO
INCH RAINFALL AMOUNTS.  COVERAGE IS VERY SPARSE.  THE FORCING IS
WEAK...BUT IS THERE.  WITH NO CAP IN PLACE THE AVAILABLE CAPE IS
ABLE TO BE REALIZED IN SPITE OF WEAK FORCING. THE CONDITIONS ARE
LIT EXPECTED TO CHANGE MUCH DURING THE DAY WITH THE UPPER LOW
MOVING NORTH GRADUALLY. WITH HEATING THE COVERAGE OF THUNDERSTORMS
WILL LIKELY INCREASE. WILL KEEP WITH ISOLATE WORDING HOWEVER.
TEMPERATURES TODAY ARE EXPECTED TO BE SIMILAR TO YESTERDAY. THE
FLY IN THE OINTMENT WILL BE THE MORE EXTENSIVE CLOUD COVE.

.LONG TERM /TONIGHT THROUGH FRIDAY/...
ISSUED AT 324 AM CDT SAT SEP 27 2014

MAIN FORECAST CONCERN DEALT WITH ABOVE NORMAL TEMPERATURES
THROUGH EARLY NEXT WEEK AND PRECIPITATION CHANCES MID TO LATE NEXT
WEEK. MODELS IN RELATIVELY GOOD AGREEMENT THROUGH MUCH OF THE
EXTENDED PERIOD AND LEANED TOWARD A BLEND OF THE SREF/NAM12
THROUGH MONDAY THEN GFS/ECMWF THEREAFTER.

TONIGHT THROUGH TUESDAY...A LARGE AREA OF HIGH PRESSURE WILL
REMAIN IN PLACE DURING THIS PERIOD AND LOOKS TO PROVIDE WELL
ABOVE TEMPERATURES AND DRY CONDITIONS SUNDAY AND MONDAY. TWEAKED
UP MAX TEMPS ACROSS THE SOUTHERN HALF OF THE FORECAST AREA ON
SUNDAY AND THROUGHOUT THE ENTIRE FORECAST AREA ON MONDAY WITH
ENOUGH MIXING AND CLEAR SKIES BOTH AFTERNOONS THAT TEMPS SHOULD
ALLOW TEMPS TO WARM ABOVE GUIDANCE. THIS WAS WELL ABOVE THE
GFS...AND ONLY SLIGHTLY ABOVE THE SREF/NAM12/ECMWF BOTH DAYS.
LITTLE COOLER ON TUESDAY WITH INCREASING CLOUDINESS AHEAD OF NEXT
TROUGH TO SLOWLY MOVE INTO THE REGION. KEPT LOW CHANCE POPS
ACROSS THE WEST AND CUT BACK ON POPS FURTHER EAST UNTIL TUESDAY
NIGHT WITH MODELS DEPICTING A SLOWER PROGRESSION. DEEP FORCING
AND THETA-E ADVECTION BEGIN TO MOVE ACROSS THE FORECAST AREA PAST
18Z TUESDAY INTO THE EVENING HOURS...SO HAVE HIGH CHANCE POPS BY
TUESDAY NIGHT.

WEDNESDAY INTO FRIDAY...GOOD MOISTURE TRANSPORT AND ISENTROPIC
LIFT PERSIST ACROSS IOWA FROM WEDNESDAY INTO THURSDAY AS A SLOW
MOVING AREA OF SURFACE LOW PRESSURE AND A LARGE UPPER LEVEL RIDGE
WITH A FEW EMBEDDED SHORTWAVES TRANSITION ACROSS THE REGION. KEPT
LIKELY POPS WEDNESDAY NIGHT INTO THURSDAY AS MODELS IN GREAT
AGREEMENT WITH SCENARIO AND HAVE BEEN THE LAST COUPLE OF MODEL
RUNS. FRONT/TROUGH FINALLY MOVE EAST BY EARLY FRIDAY MORNING
BRINGING TEMPERATURES BACK TO NEAR OR SLIGHTLY BELOW NORMAL BY THE
END OF THE WORK WEEK.

&&

.AVIATION...27/18Z
ISSUED AT 1239 PM CDT SAT SEP 27 2014

SLOW MOVING UPPER LOW WILL CONTINUE TO MEANDER ACROSS IOWA DURING
NEXT 24 HOURS BEFORE DEPARTING. WHILE THIS LOW WILL LIKELY PRODUCE
SOME ISOLATED SHRA/TSRA ACTIVITY THIS AFTERNOON INTO THIS
EVENING...MOST LOCATIONS WILL SEE LITTLE IF ANY IMPACT. HAVE KEPT
ALL TAF SITES VFR FOR THE DURATION OF THE FORECAST WITH LIGHT
SOUTHEAST WINDS. SOME PATCHY FOG WILL BE POSSIBLE LATE TONIGHT
WITH LIGHT FLOW AND RESIDUAL MOISTURE FROM SPOTTY
SHOWERS...HOWEVER THE ISOLATED NATURE PRECLUDED MENTIONING IN TAFS
AT THIS POINT.

&&

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

&&

$$

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


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