Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 290852
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
352 AM CDT SUN MAR 29 2015

.SHORT TERM /TODAY/...
ISSUED AT 350 AM CDT SUN MAR 29 2015

STRONG WARM ADVECTION ONGOING AHEAD OF APPROACHING SHORTWAVE WITH
THETA-E ADVECTION ALSO MAXIMIZED IN CENTRAL IOWA CURRENTLY. HAVE
SEEN SHOWERS MOVE INTO THE WEST AND EXPAND SOMEWHAT OVER THE PAST
COUPLE OF HOURS.  FORWARD PROGRESS IS CLOSE TO 50KTS AND EXPECT THIS
BAND TO CONTINUE TO PRESS QUICKLY EASTWARD WITH THE THETA-E
ADVECTION THIS MORNING.  MUCH OF THE THREAT OF PRECIPITATION WILL BE
OVER BY SUNRISE ACROSS THE FORECAST AREA EXCEPT FOR THE FAR EAST AND
SOUTH.  EVEN THIS THREAT WILL DIMINISH BY MID TO LATE MORNING AS THE
SURFACE FRONT PUSHES ACROSS THE STATE.  ONLY REMAINING THREAT FOR
PRECIPITATION WILL BE WRAP-AROUND NEAR UPPER SYSTEM APPROACHING
NORTHERN IOWA.  AT THIS POINT...MOST MODELS KEEP THIS NORTH OF THE
BORDER AND HAVE THEREFORE LEFT THE FORECAST DRY INTO THIS AFTERNOON.

OTHERWISE...OTHER ISSUE WILL BE THE WIND WITH STRONG PRESSURE RISES
ON THE BACKSIDE OF THE FRONT.  ANTICIPATE WINDS FROM THE WEST
NORTHWEST TO INCREASE WITH MIXING BY LATER THIS MORNING WITH VERY
STRONG WINDS FOR MUCH OF THE AREA THIS AFTERNOON. SOUNDINGS INDICATE
WINDS AT THE TOP OF THE MIXED LAYER AROUND 45KTS ACROSS NORTHERN
IOWA AND COULD SEE SOME GUSTS OF 50MPH THERE.  THERE APPEARS TO BE A
FEW HOUR WINDOW IN EARLY AFTERNOON WHERE MUCH OF THE NORTHWEST HALF
OF FORECAST AREA SHOULD SEE SOME ADVISORY CRITERIA WITH SUSTAINED
WINDS OF 30 MPH AND GUSTS APPROACHING 45 MPH.  HAVE EXPANDED THE
ADVISORY AREA TO INCLUDE MUCH OF THE NORTHWEST HALF OF THE FORECAST
AREA WHERE WINDS TEND TO BE STRONGER THAN THE HILLIER TERRAIN OF THE
SOUTH AND EAST.  THE DECENT MIXING WILL HELP TEMPERATURES TO CLIMB
ABOVE NORMAL TODAY ALONG WITH CLEARING SKIES BY THIS AFTERNOON.

.LONG TERM /TONIGHT THROUGH SATURDAY/...
ISSUED AT 350 AM CDT SUN MAR 29 2015

THE MAIN CHANGES TO THIS FORECAST WERE TO ADD SOME DETAIL TO
WEDNESDAY.  I DO NOT HAVE ANY POPS IN THE FORECAST GRIDS BEFORE
WEDNESDAY AFTERNOON.  UPPER LEVEL RIDGING IS VERY IMPRESSIVE OVER
THE ROCKIES AND MODELS HAVE SHIFTED THE RIDGE AXIS A BIT FURTHER
EAST SO THE SHORTWAVES PROGGED TO RIDE THE RIDGE WILL IMPACT AREAS
FURTHER EAST THUS MISSING THE NORTHEAST PORTIONS OF THE FORECAST
AREA.  WEDNESDAY REMAINS VERY INTERESTING AND MODELS HAVE SLOWED THE
VERY POTENT SHORTWAVE AND ATTENDANT FRONTAL PASSAGE NOW INTO THE
LATE AFTERNOON/EVENING HOURS.  THIS IS A LITTLE OUTSIDE PEAK HEATING
AND THE BEST INSTABILITY BUT THIS SYSTEM IS DYNAMIC AND SHEAR IS
PRETTY IMPRESSIVE WITH DEEP LAYER SHEAR AROUND 55KTS.  IT STILL
LOOKS AS THOUGH A FEW STORMS COULD BECOME SEVERE...ESPECIALLY
NORTHWEST IN THAT LATE AFTERNOON/EARLY EVENING PERIOD.  SHOWERS AND
STORMS WILL HOWEVER LINGER INTO WEDNESDAY NIGHT.  THE EURO AND
CANADIAN ARE HOLDING ON TO PRECIP EVEN INTO THURSDAY MORNING BUT THE
SYSTEM IS PRETTY PROGRESSIVE AND I DON`T SEE A BIG CHANCE FOR PRECIP
INTO THURSDAY MORNING EXCEPT FOR THE FAR SOUTHEAST.  STILL WITH TWO
OUT OF THE THREE MEDIUM RANGE MODELS SUGGESTING LINGERING
PRECIP...AND IN KEEPING WITH COLLABORATION OF OTHER OFFICES...I DID
KEEP SLIGHT CHANCES GOING ACROSS LOCATIONS SOUTH OF HIGHWAY 20 INTO
THURSDAY BUT THIS WOULD BE MAINLY EARLY TO MID MORNING.

AS FOR TEMPS THROUGH MID WEEK...WE WILL BE VERY WARM WITH WEDNESDAY
LIKELY BEING THE WARMEST OF THE DAYS AS A STRONG SOUTHERLY/
SOUTHWESTERLY FLOW GETS ESTABLISHED AHEAD OF THE UPPER TROUGH AND
FRONT WHICH AS PREVIOUSLY MENTIONED...WILL NOW BE PASSING THROUGH
LATER IN THE DAY.  I DID NUDGE HIGHS A DEGREE OR TWO HIGHER THAN
MODEL BLENDS WERE GIVING ME AND THIS MAY STILL BE TOO COOL.

AFTER THURSDAY...THE PATTERN GETS MESSY AND MODELS ARE NOT HANDLING
THINGS WELL.  YESTERDAY THEY HAD A PRETTY ACTIVE SOUTHERN STREAM
THAT WAS BRINGING PRECIP INTO THE REGION.  NOW THE CANADIAN IS THE
ONLY MODEL THAT IS REALLY KEEPING PRECIP GOING BUT MODEL BLENDS
STILL BLEND THE LAST RUNS POP/QPF INTO THIS RUN...WHICH IS WHY IT
WAS STILL GIVING ME CHANCE POPS.  FOR NOW I DID KNOCK POPS BACK BUT
DID NOT REMOVE IT COMPLETELY PRIMARILY BECAUSE IT WAS A BIG SHIFT
FROM PREVIOUS RUNS AND CONFIDENCE IS NOT THAT HIGH THAT THE MODELS
CURRENT SOLUTION IS CORRECT.  DAY SHIFT WILL CONTINUE TO EVALUATE
AND I WILL TAKE ANOTHER LOOK TONIGHT AND CONSIDER BIGGER CHANGES IF
THE DAY SHIFT HASN`T ALREADY AND MODELS ARE STILL POINTING TO A
FURTHER SOUTH SHIFT TO PRECIP.  THE TROUGH OVER THE UPPER MIDWEST
WILL BRING AN END TO THE 70 DEGREE READINGS THOUGH AND HIGHS WILL BE
BACK INTO THE 50S AND 60S...WHICH HAS BEEN CONSISTENT FROM THE PAST
FEW DAYS.

NEXT SHOT AT PRECIP REALLY DOESN`T COME UNTIL THE END OF THE
EXTENDED WHEN THE MODELS BRING A FRONTAL BOUNDARY INTO THE STATE.
HOWEVER MOISTURE LOOKS A LITTLE CUT OFF AT THIS POINT SO I TOOK
ANY POPS OUT FOR NOW.

&&

.AVIATION...29/06Z
ISSUED AT 1203 AM CDT SUN MAR 29 2015

VFR/CLEAR SKIES ARE ANTICIPATED INTO THE EARLY MORNING HOURS...HOWEVER
ATTENTION WILL TURN UPSTREAM TO PROGRESSION OF CURRENT DAKOTAS
ELEVATED CONVECTION WHICH MAY BEGIN REACHING NW TAF SITES AROUND
08Z. FOR NOW HAVE VCSH/-SHRA WORDING AND GENERALLY STILL VFR
ALTHOUGH VSBYS OR CIGS MAY BRIEFLY TOUCH MVFR AS WELL. BETTER
CHANCES ACROSS SERN SITES /KDSM/KALO/KOTM/. NO THUNDER MENTION AS
OF YET UNTIL TIMING AND LOCATION CONFIDENCE INCREASES. WINDS WILL
PICK UP INTO THE MORNING AND INCREASE FURTHER WITH FROPA SUN.
GUSTS WILL OFTEN EXCEED 30KTS BY THEN...REACHING WELL INTO THE 30S
NORTH AND WEST UNTIL DIURNAL LOSS OF MIXING BY EARLY EVENING.


&&

.FIRE WEATHER...
ISSUED AT 350 AM CDT SUN MAR 29 2015

WINDS WILL CERTAINLY BE STRONG ENOUGH TO SPREAD FIRES RELATIVELY
QUICKLY TODAY WITH STRONG PRESSURE RISES ON THE BACKSIDE OF THE
FRONT.  HOWEVER...RELATIVE HUMIDITY VALUES REMAIN FROM 30 TO 50
PERCENT THIS AFTERNOON WHICH WILL PRECLUDE A RED FLAG WARNING AT
THIS TIME.  WILL STILL HIGHLIGHT AN ENHANCED FIRE POTENTIAL IN THE
HWO AND POSSIBLY AN SPS.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 10 AM THIS MORNING TO 6 PM CDT THIS EVENING
FOR ADAIR-AUDUBON-BLACK HAWK-BOONE-BREMER-BUTLER-CALHOUN-CARROLL-
CASS-CERRO GORDO-CRAWFORD-DALLAS-EMMET-FRANKLIN-GREENE-GRUNDY-
GUTHRIE-HAMILTON-HANCOCK-HARDIN-HUMBOLDT-KOSSUTH-MARSHALL-PALO
ALTO-POCAHONTAS-POLK-SAC-STORY-WEBSTER-WINNEBAGO-WORTH-WRIGHT.

&&

$$

SHORT TERM...COGIL
LONG TERM...FAB
AVIATION...SMALL
FIRE WEATHER...COGIL



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