Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 302331
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
631 PM CDT THU APR 30 2015

.SHORT TERM /TONIGHT/...
ISSUED AT 355 PM CDT THU APR 30 2015

HIGH PRESSURE FROM LAKE SUPERIOR INTO EASTERN KANSAS WILL DRIFT
EAST WITH THE FLOW BECOMING SOUTHEASTERLY OVERNIGHT.  OTHER THAN
HIGH AND SOME MID LEVEL CLOUDS...FEEL MUCH OF THE ACTION WILL REMAIN
NORTHWEST OF IOWA TONIGHT.  SOME SHOWERS WILL MOVE INTO THE
NORTHWEST PART OF THE CWA BY MORNING.  SUPPORT IS WEAK WITH LIMITED
INSTABILITY AND ONLY WEAK THETA-E ADVECTION.

.LONG TERM /FRIDAY THROUGH THURSDAY/...
ISSUED AT 355 PM CDT THU APR 30 2015

MUCH MORE ACTIVE WX PATTERN SETTING UP FOR THIS WEEKEND INTO NEXT
WEEK. BY THE START OF THE FCST PERIOD...A VERY WEAK BOUNDARY WILL BE
CROSSING INTO IOWA FROM THE W/NW. BOUNDARY MOTION WILL SHIFT FROM
MORE N TO S THROUGHOUT FRI...PUSHING NEAR TO THE IA/MO BORDER SAT
AM. THE NAM IS THE MOST BULLISH ON MOISTURE AND LIFT WITH THIS
SYSTEM. THE EURO IS INITIALIZING THE BEST WITH HANDLING MOISTURE
SOURCE IN THE SOUTH CENTRAL US...SO WILL LEAN TOWARDS THE EURO.
1000MB PWATS RANGE FROM AROUND 0.5 TO 1.5 STD ABOVE NORMAL. MUCAPE
VALUES MINIMAL AND OTHER SVR WX PARAMETERS INDICATE NO SVR WX
THREAT FRI PM. ALL FCST SOUNDINGS KEEP THE LOWEST 1 KM FAIRLY DRY
EAST OF I-35...SO KEPT POPS WEST AND SOUTH.

FOR SATURDAY PM...THE GULF OPENS UP AND MOISTURE CONTINUES TO
INCREASE THROUGHOUT THE CWA AS DWPTS LOOK TO MAKE IT INTO THE 50S.
1000MB PWAT VALUES JUMP TO +1 TO +2 STD DEV. THE NAM HAS 0-6KM
MUCAPE VALUES HITTING 2000 J/KG IN OUR WEST...WHEREAS THE GFS KEEPS
THESE VALUES UNDER 1000 J/KG. THE EURO LIES IN THE MIDDLE. 0-6KM
BULK SHEAR VALUES HIT 40 KTS IN OUR SW CWA. BIGGEST CHALLENGE FOR
STORMS TO FIRE WILL BE LACK OF SIGNIFICANT TRIGGER. SOME POSITIVE
THETA-E ADVECTION BEING NOTED ALONG THETA-E AXIS IN SW IA...BUT
LOOKING PRETTY MINIMAL. IN ALL...EXPECTING CU COULD LEAD TO SCTDSTORMS
ACROSS MUCH OF CWA...WITH BEST CHANCE OF ANY SVR WX BEING IN THE
SW CWA AND HAIL BEING THE MAIN THREAT.

SUNDAY LOOKS TO BE THE WARMEST DAY OF THE NEXT 5 AS H850 TEMPS HIT
THE 14C RANGE...1 TO 2 STD DEV ABOVE NORMAL. GFS REALLY BUYING IN ON
CIRRUS SHIELD WHICH SEEMS OVERDONE AT THIS POINT. THUS HAVE WARMED
TEMPS ABOVE GUIDANCE INTO LOW TO MID 80S. FOR PRECIP
CHANCES...SUNDAY IS INTERESTING. MODELS LOADING UP IN THE MORNING
HOURS...HOWEVER AM NOT SEEING MUCH JUSTIFICATION FOR THIS SO AM
LOWERING MORNING POPS. A FRONTAL BOUNDARY WILL BE APPROACHING THE
CWA FROM THE NW LATER IN THE DAY. THIS WILL SERVE AS A FOCUSING
MECHANISM FOR SHOWERS AND STORMS IN THE NORTH SUNDAY EVENING...AND
THE REST OF IOWA AS THE NIGHT PROGRESSES INTO MONDAY MORNING. ENOUGH
MOISTURE REMAINS IN PLACE AS PWAT VALUES REMAIN AT +1 TO +2 STD
DEV.

MONDAY AND TUESDAY...THE AFOREMENTIONED COLD FRONT WILL CONTINUE TO
PASS THROUGH OUR CWA...STALLING OUT OVER SOUTHERN IOWA INTO TUESDAY
MORNING. DURING THE DAY TUESDAY...THIS FRONT WILL SLOWLY MIGRATE
BACK NORTH TOWARDS I-80. PWAT VALUES AND MOISTURE INCREASE TO +1.5
TO +2.5 ACROSS THE SOUTH. RIVER STAGES ARE STARTING OFF LOW...BUT
WILL LIKELY NEED TO MONITORED MORE CLOSELY TUESDAY INTO
WEDNESDAY.

SOME CONSISTENCY IS BEGINNING TO BUILD FOR A SVR WX THREAT WEDNESDAY
PM. A LITTLE TOO FAR OUT IN THE EXTENDED TO GET INTO TOO MUCH
DETAIL...BUT CERTAINLY BEARS WATCHING. GFS AND EURO IN FAIRLY GOOD
AGREEMENT WITH BRINGING 500 MB LOW FROM THE FOUR CORNERS REGION INTO
THE GREAT PLAINS. THE EURO IS ACTUALLY SLIGHTLY FASTER WITH THIS
SYSTEM. AT THE VERY LEAST...CONFIDENCE BEGINNING TO GROW IN
STRONG SOUTHERLY FLOW. RAISED TEMPS TO THE UPPER 70S WITH 80S VERY
POSSIBLE. THE REGION LOOKS TO REMAIN IN SOUTHERLY FLOW INTO NEXT
WEEKEND...MEANING TEMPS SHOULD REMAIN ABOVE NORMAL WITH PRECIP
CHANCES CONTINUING.

&&

.AVIATION...01/00Z
ISSUED AT 628 PM CDT THU APR 30 2015

VFR CONDITIONS ARE FORECAST THROUGH NOON FRIDAY AND POSSIBLY
BEYOND. WINDS WILL COME AROUND TO SOUTHEAST OVERNIGHT THEN
SOUTHWEST BY FRIDAY AFTERNOON AS A WEAKENING PRESSURE TROUGH
APPROACHES. THIS TROUGH WILL BE ACCOMPANIED BY LAYERED CLOUDS AND
SOME SHOWERS AND ISOLATED THUNDERSTORMS...BUT PROBABILITY AT A
GIVEN TERMINAL IS TOO LOW FOR TAF INCLUSION AT THIS RANGE EXCEPT A
VCSH AT FOD/MCW.

&&

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

&&

$$

SHORT TERM...MS
LONG TERM...KOTENBERG
AVIATION...LEE


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