Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 281154
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
654 AM CDT FRI AUG 28 2015

.SHORT TERM /TODAY/...
ISSUED AT 330 AM CDT FRI AUG 28 2015

PRECIP TRENDS WILL BE THE STRAIGHT FORWARD FORECAST ISSUE TODAY WITH
SOME TEMP REBOUND CONCERNS AS WELL. UPPER LEVEL FLOW WILL CONTINUE
TO AMPLIFY TODAY WITH PASSAGE OF MID LEVEL WAVE THROUGH THE MO
VALLEY. BOTH KINEMATIC AND THERMODYNAMIC FORCING ARE STRONGLY NOTED
WITH SOME RIGHT ENTRANCE REGION SUPPORT FROM WI/MI SPEED MAX AND
DPVA AHEAD OF ERN NE SHORT WAVE MECHANICALLY. FAIRLY DECENT
BAROCLINIC ZONE IS ALSO NOTED ON 305K ISENT SURFACE WITH NAM
DEPICTING OVER 100 MB OF LIFT ACROSS IA BY 12Z WITH 40-50KTS OF
FLOW. THIS RESULTS IN VERY STRONG MOISTURE TRANSPORT AND ASSOCIATED
CONVERGENCE ZONES...WHICH MOVE SLOWLY ACROSS IA REACHING NERN
SECTIONS BY EARLY AFTERNOON.  ALTHOUGH THE FORCING IS STRONG WITH
PWATS AND WARM CLOUD DEPTHS SEASONALLY HIGH SUGGESTING HIGH RAINFALL
EFFICIENCY...THE LACK OF INSTABILITY WILL HOLD THINGS BACK SOMEWHAT
WITH CONVECTION ONLY EMBEDDED WITHIN LARGER STRATIFORM AREA.
RAINFALL AMOUNTS WILL STILL EXCEED AN INCH IN MANY LOCATIONS HOWEVER
WITH POSSIBLY OVER TWO INCHES IN THE CENTRAL AND ERN I80 TO HIGHWAY
20 ZONES.  AGREE WITH WPC QPF ASSESSMENT FAVORING THIS FARTHER SOUTH
MAX AXIS.  DO NOT FEEL RAINFALL RATES WILL BE SUFFICIENT TO JUSTIFY
ANY HEADLINES AT THIS POINT HOWEVER.

TEMP REBOUND WILL BE SOMEWHAT OF A MINOR CONCERN. SOUNDINGS SUGGEST
THERE MAY BE A LITTLE MIXING BOOST IN THE WARM SECTOR FOR S CENTRAL
AND SERN SECTIONS BY AFTERNOON BEHIND THE MAIN PRECIP SHIELD...WHICH
MAY ALSO REDEVELOP SOME SHOWERS OR ISOLD STORMS...BUT CLOUDS AND
PRECIP SHOULD OFFSET TOO MUCH OF A REBOUND SO STAYED CLOSER TO
WARMER MOS RATHER THAN WHAT SOME RAW TEMPS SUGGEST. ACROSS THE
NORTH...CLOUDS PRECIP AND AN UNFAVORABLE MORE ELY WIND SHOULD KEEP
ANY REBOUND TO A MINIMUM. HOWEVER SHEAR MOISTURE ADDITION FROM
PRECIP AND TRANSPORT SHOULD NUDGE THINGS UP SEVERAL DEGREES DURING
THE HEATING OF THE DAY.

.LONG TERM /TONIGHT THROUGH THURSDAY/...
ISSUED AT 330 AM CDT FRI AUG 28 2015

FOCUS IS MAINLY ON TEMPERATURES THROUGHOUT THE PERIOD...AND POPS
TONIGHT. SFC LOW ASSOCIATED WITH THE STRONG SHORTWAVE TROUGH
DROPPING THROUGH THE REGION TODAY INTO TONIGHT...WILL BE CENTERED
NEAR DES MOINES BY 00Z THIS EVENING. MUCH OF THE PRECIP EXPECTED TO
BE ON THE WARM SIDE OF THE LOW AND THUS AS THE SFC TROUGH AXIS
SHOVES EASTWARD THROUGH THE CWA TONIGHT...EXPECT PRECIP CHANCES TO
DIMINISH. HIGHER LOW LEVEL MOISTURE NOTED WITH THE MODELS SO DO
EXPECT AN AREA OF LINGERING LOW STRATUS ACROSS MUCH OF THE CWA INTO
EARLY SATURDAY WITH THE CLOUD DECK SLOWLY ERODING/PUSHING ESE
THROUGH THE DAY. WITH ALL THE RESIDUAL MOISTURE AROUND AFTER THE
RAIN...SOME CLEARING POSSIBLE ACROSS THE FAR WEST TONIGHT...AND
LIGHTER WINDS SETTING IN COULD SEE SOME FOG DEVELOPMENT. PREVIOUS
GRIDS HAD IT MENTIONED ACROSS THE WESTERN THIRD OF THE CWA...SO
STUCK WITH THAT AREAL COVERAGE BUT DID EXTEND THE MENTION INTO
SATURDAY MORNING. OTHERWISE LARGE UPPER RIDGE ACROSS THE CENTRAL US
TO AMPLIFY INTO BUILD EASTWARD INTO NEXT WEEK. THIS WILL BRING
WARMING AS THE THERMAL RIDGE BUILDS INTO THE AREA AND MAINLY DRY
CONDITIONS. MODELS TRY TO BRING A FEW IMPULSES MOVING THROUGH THE
RIDGE TUESDAY NIGHT AND AGAIN WEDNESDAY NIGHT...AND MAY SEE AN
ISOLATED SHOWER/THUNDERSTORM. BETTER CHANCES TO THE NORTH AND WEST.
THEREFORE DID KEEP MUCH OF THE PERIOD DRY WITH JUST SOME SLIGHT
CHANCE POPS ACROSS THE FAR NORTHWEST TUESDAY NIGHT.

H85 TEMPS COOLER TO BEGIN THE PERIOD IN THE TEENS CELSIUS WITH
LINGERING CLOUD COVER INTO SATURDAY ESPECIALLY ACROSS THE EAST.
THEREFORE KEPT TEMPS A BIT COOLER IN THE MID TO UPPER 70S. AS THE
WARMER AIRMASS BUILDS INTO THE REGION AND H85 TEMPS EXPECTED TO PUSH
INTO THE LOW TO MID 20S CELSIUS TOWARD MID/LATE WEEK HAVE HIGHS
WARMING INTO THE MID TO UPPER 80S AND LOWS IN THE 60S. DEWPOINTS
ALSO EXPECTED TO INCREASE BACK INTO THE MID TO UPPER 60S TOWARD NEXT
WEEK MAKING THINGS FEEL A BIT MORE HUMID.

&&

.AVIATION...28/12Z
ISSUED AT 654 AM CDT FRI AUG 28 2015

SHOWERS WILL AFFECT TAF SITES TO VARIED DEGREES THROUGH THE
MORNING WITH MOST DEGRADED CONDITIONS OVER NRN IA
/KFOD/KMCW/KALO/. THERE MAY BE A FEW PERIODS OF THUNDER...BUT ONLY
MENTION WILL BE NEAR KFOD FOR THE TIME BEING UNTIL TRENDS AND
CONFIDENCE BECOME MORE CLEAR. PRECIP POTENTIAL WILL BE MORE
SCATTERED BY AFTERNOON WITH MAIN CONCERN TURNING TO CIGS/VSBYS.
HAVE DROPPED NRN SITES TO IFR AS LOW LEVEL MOISTURE LINGERS AND
WINDS DECREASE. HAVE SIMILAR TRENDS SOUTH BUT HOLDING OFF UNTIL
LATE IN THE PERIOD. CONFIDENCE IN DETAILS THAT FAR OUT IS LOW
HOWEVER.

&&

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

&&

$$

SHORT TERM...SMALL
LONG TERM...BEERENDS
AVIATION...SMALL


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