Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 092325
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
625 PM CDT WED APR 9 2014

.SHORT TERM /TONIGHT/...
ISSUED AT 256 PM CDT WED APR 9 2014

MAIN CONCERN IS WITH WEAK COLD FRONT TO PUSH ACROSS THE STATE
EARLY THURSDAY MORNING AND BRING SMALL POTENTIAL OF SHOWERS
OVERNIGHT. LIMITED MOISTURE AVAILABLE WITH SYSTEM BUT SOME WEAK
MID-LEVEL THETA-E ADVECTION AHEAD OF FRONTAL BOUNDARY FROM 03- 09Z
THURSDAY. STILL PLENTY OF DRY AIR FROM THE SURFACE TO ABOUT 600MB
PER MCW/DSM BUFR SOUNDINGS. SO ANY SORT OF SHOWER WILL BE VERY
LIGHT AND HAVE LOW CONFIDENCE WITH MORE THAN 0.01 QPF OVERNIGHT.
LEANED TOWARD A BLEND OF THE SREF/NAM FOR POPS AND SREF FOR
TEMPERATURES. WAA CONTINUES THROUGH MUCH OF THE NIGHT BEFORE THE
COLD FRONT SWEEPS THROUGH PAST 09Z. CONFIDENT TO BUMP MINIMUM
TEMPS UP SLIGHTLY FOR TONIGHT.

.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
ISSUED AT 256 PM CDT WED APR 9 2014

WEAK BOUNDARY EXPECTED TO EXIT THE AREA BY NOON TOMORROW WITH
WEAKENING FORCING THROUGH THE MORNING HOURS. HAVE LEFT SLIGHT
CHANCES OF RAIN SHOWERS ACROSS THE EAST/SOUTHEAST THROUGH NOON WITH
DRYING CONDITIONS FOR THE REMAINDER OF AFTERNOON. AIRMASS BEHIND
BOUNDARY NOT ALL THAT COLD...SO HIGHS THURSDAY WILL RECOVER TO THE
LOWER TO MID 60S. ALREADY ANOTHER TROUGH REPLACES THE EXITING RIDGE
BY EARLY FRIDAY WITH WARM AIR ADVECTION THROUGH MUCH OF THE DAY.
H850 TEMPS WARM TO 9-10C ACROSS THE AREA WITH SOME MIXING EXPECTED.
HAVE WARMED HIGHS BACK INTO THE UPPER 60S TO LOWER 70S WITH AMPLE
SUNSHINE. AS THE NORTHERN AND SOUTHERN STREAM LONG WAVE TROUGH
BEGINS TO AMPLIFY OVER THE WEST US LATE FRIDAY/EARLY SATURDAY A
PIECE OF ENERGY WILL REACH THE PLAINS/IOWA BY LATE FRIDAY NIGHT
AND SATURDAY. MODEL CONSENSUS IS DRIFTING...BUT NAM/GFS/EURO
SUGGEST THAT WARM AIR ADVECTION AND WARM FRONTAL BOUNDARY NEAR
CENTRAL IOWA SHOULD LIGHT UP TOWARD 12Z SATURDAY WITH POTENTIAL
FOR THUNDERSTORMS. QUICKLY A FRONT DROPS SOUTH AND CONTINUES
CHANCES FOR THUNDER DURING THE AFTERNOON AND EVENING AS
AMPLIFICATION OF THE SOUTHERN WAVE BECOMES MORE PRONOUNCED.
PREVIOUS MODEL PACKAGES HAVE BEEN SPLIT ON THE AMOUNT OF PHASING
WITH THE 12Z TUE EURO PHASING THE SYSTEM WITH A PROLONGED PERIOD
OF RAIN SUNDAY INTO MIDDAY MONDAY. TODAYS GUIDANCE AND LAST NIGHTS
00Z EURO NOW SUGGESTING LESS PHASING AND THE 12Z RUN ABOUT THE
SAME SOLUTION...AND A MORE SOUTHERN TRACK OF THE SOUTH SYSTEM. THE
SHIFT IN FORECAST WILL HAVE SIGNIFICANT IMPLICATIONS FOR RAINFALL
AMOUNTS ACROSS THE AREA. GIVEN THE TENDENCY FOR MODELS TO WIGGLE A
BIT...WILL NEED TO VERIFY OVER THE NEXT DAY OR TWO TO SEE IF THE
TREND IS CONFIRMED. FOR NOW WILL LEAN TOWARD A WET PERIOD THROUGH
SUNDAY WITH THE SYSTEM EXITING THE REGION MONDAY. THERE IS STILL A
POTENTIAL FOR 1 TO 2 INCH RAINFALL TOTALS OVER THE WEEKEND. GIVEN
THE POTENTIAL FOR TIMING ISSUES ON SATURDAY...TEMPS BECOME FAIRLY
DIFFICULT QUICKLY. HAVE WARMED HIGHS SOUTH OF THE BOUNDARY SAT.
TEMPS SUNDAY AND MONDAY WILL COOL OFF QUICKLY...BUT UNCERTAINTY
REMAINS REGARDING THE AMOUNT. HAVE SETTLED ON MID 40S NORTH TO
UPPER 50S SOUTHEAST. WITH DEPARTING SYSTEM AND COOLER AIR BEING
ENTRAINED INTO THE EXITING LOW...A RASN MIX IS STILL POSSIBLE LATE
SUNDAY NIGHT INTO MONDAY MORNING. HIGHS MONDAY WITH H850 TEMPS OF
-6 TO -7C AT 18Z WILL BE IN THE 40S TO NEAR 50 WITH SOME
SUN...OTHERWISE A BIT COOLER. LESS CERTAINTY REMAINS FOR TUE/WED
WITH ANOTHER COLD FRONT DROPPING SOUTH TUESDAY. GFS/EURO DIFFER ON
EVOLUTION AND CONFIDENCE REMAINS LOW. CONTINUE TO LEAN TOWARD EURO
SOLUTION WHICH SUGGESTS COLDER WEATHER THROUGH MIDWEEK.

&&

.AVIATION...10/00Z
ISSUED AT 622 PM CDT WED APR 9 2014

SOUTHWEST FLOW WILL DIMINISH AS COLD FRONT FROM NWRN MN INTO SWRN
SD MOVES INTO IA TONIGHT AND SOUTHEAST OF THE TAF SITES BY
MORNING. VFR CONDITION WITH A FEW SHOWERS BEHIND THE FRONT. BUSTY
NWLY WINDS ON THU.

OUTLOOK...VFR THROUGH FRI AS HIGH PRESSURE MOVES INTO THE STATE.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR ADAIR-ADAMS-
APPANOOSE-AUDUBON-BLACK HAWK-BOONE-BREMER-BUTLER-CALHOUN-CARROLL-
CASS-CERRO GORDO-CLARKE-CRAWFORD-DALLAS-DAVIS-DECATUR-EMMET-
FRANKLIN-GREENE-GRUNDY-GUTHRIE-HAMILTON-HANCOCK-HARDIN-HUMBOLDT-
JASPER-KOSSUTH-LUCAS-MADISON-MAHASKA-MARION-MARSHALL-MONROE-PALO
ALTO-POCAHONTAS-POLK-POWESHIEK-RINGGOLD-SAC-STORY-TAMA-TAYLOR-
UNION-WAPELLO-WARREN-WAYNE-WEBSTER-WINNEBAGO-WORTH-WRIGHT.

&&

$$

SHORT TERM...PODRAZIK
LONG TERM...REV
AVIATION...MS APR 14



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