Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 252355
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
650 PM CDT THU JUN 25 2015

.SHORT TERM /TONIGHT/...
ISSUED AT 356 PM CDT THU JUN 25 2015

MAIN FORECAST CONCERN WAS FOCUSED ON WEAK SHORTWAVE
CUTTING ACROSS NEBRASKA AND POTENTIALLY BRINGING SOME LOCALLY HEAVY
RAIN TO FAR SOUTHERN IOWA TONIGHT. BOUNDARY LOOKS TO BE SET UP IN
NORTHERN MISSOURI AND POSSIBLY SHIFT NORTH ENOUGH TO THE IOWA BORDER
TONIGHT...BUT HAVE FAIRLY HIGH CONFIDENCE THAT IS THE FARTHEST
EXTENT NORTH IT WILL REACH. DECENT MOISTURE CONVERGENCE ALONG THE
MO/IA BORDER WITH STILL A GOOD ATMOSPHERE FOR EFFICIENT RAIN
PRODUCERS. PRECIPITABLE WATER VALUES AROUND 1.5 INCHES AND WARM
LAYER CLOUD DEPTHS IN THE 3500-3800 METER RANGE. FORWARD PROPAGATION
CORFIDI VECTORS ORIENTED WEST TO EAST PROVIDING SOME TRAINING
POTENTIAL ALONG THE FAR SOUTH. THE 25.19Z HRRR KEEPS MUCH OF THE
HEAVY CONVECTION IN MISSOURI. HOWEVER...INCREASED POPS AND QPF OVER
THE SOUTHERN TIER OF COUNTIES ALONG THE MISSOURI BORDER. OTHER
CONCERN WAS ANOTHER WEAK SHORTWAVE TO PROVIDE SOME ELEVATED SHOWERS
AND ISOLATED THUNDERSTORM OVER THE REMAINDER OF THE FORECAST AREA.
QPF AMOUNTS SHOULD REMAIN UNDER QUARTER OF AN INCH AND THUS LOW
IMPACT ON ANY ONGOING FLOODING

.LONG TERM /FRIDAY THROUGH THURSDAY/...
ISSUED AT 356 PM CDT THU JUN 25 2015

A MUCH...MUCH QUIETER 7 DAYS AHEAD IN THIS LONG TERM FCST PERIOD.
WATER VAPOR IMAGERY PICKING UP ON HIGH PRESSURE COMING ONSHORE NEAR
THE OREGON COASTLINE. THIS HIGH PRESSURE WILL HAVE SIGNIFICANT
INFLUENCE ON OUR WEATHER MUCH OF NEXT WEEK.

FRIDAY MORNING...MODELS PICKING UP ON A SHORTWAVE CONTINUING THROUGH
SOUTHERN IA/NORTHERN MO. ISENTROPIC LIFT PERSISTING INTO 12Z AS THIS
SYSTEM WILL LIKELY BE CLIPPING AT LEAST THE SOUTHERN TWO TO THREE
TIERS OF COUNTIES IN IA. WITH YESTERDAY/S BOUNDARY LINGERING IN
NORTHERN MO...A LOT OF THE MOISTURE FROM THURSDAY/S SYSTEM STILL
AROUND. MODELS FOCUSING IN ON PWATS BTX 1.5 AND 1.75 INCHES...WHICH
IS AROUND +1 TO +2 STD DEV. GOOD SUPPORT ALOFT AS MID-LEVEL Q-VECTOR
CONV PRESENT TO INCREASE LIFT. 0-6KM MIXING RATIOS AROUND 7 G/KG
WHICH IS DECENT ENOUGH. OVERALL SOUNDING PROFILE MUCH LESS SATURATED
THAN MOST OF THIS WEEK...SO THIS SYSTEM WILL NOT BE THE MOST
EFFICIENT IN RAIN PRODUCTION.

FRI AFTERNOON TEMPS...850MB TEMPS AROUND 12C IN OUR EAST AND 14C IN
OUR WEST...ABOUT -1 TO -2 STD DEV. THURSDAY/S 850 MB TEMPS WERE
AROUND 14C NE TO 17C SW. AM EXPECTING SUNSHINE TO BREAK
THROUGH...BUT NOT A LOT...SO HAVE KEPT TEMPS IN THE MID 70S.

FRI AFTERNOON THUNDERSTORM POTENTIAL...0-6KM MUCAPE VALUES BTX 700
AND 1000 J/KG WHICH WHICH IS MINIMAL. 0-6KM BULK SHEAR NEAR
30KTS...ALSO MINIMAL. LCL HEIGHTS ABOVE 1000M. OVERALL SOUNDING
PROFILE SUGGESTS ANYTHING THAT FORMS WOULD BE ELEVATED. THUS
OVERALL...AM EXPECTING NIL SVR/TOR THREAT FRI PM AND THERE MAY BE A
FEW SHORT LIVED NON-SEVERE STORMS PRIMARILY IN OUR NW.

FOR SATURDAY NIGHT INTO SUNDAY EVENING...MODELS CONSISTENT WITH
PROPAGATING AN AREA OF LOW PRESSURE FROM NW MINNESOTA INTO SE
MINNESOTA. A WEAK COLD FRONT WILL BE ATTACHED TO THIS AND PUSHING
THROUGH IA DURING THE DAYTIME. THE 12Z GFS IS A FAST OUTLIER WITH
THIS SYSTEM AS IT PLACES THE BOUNDARY EAST OF OUR CWA BY 12-15Z SUN.
HAVE MAINLY DISREGARDED THE GFS AND WENT WITH AN AVERAGE OF OTHER
MODELS. PWATS JUMP FROM AROUND 1.25 TO 1.5 INCHES AND 0-6KM MUCAPE
VALUES ARE AROUND 400 TO 600 J/KG. POSITION OF FRONT DURING PEAK
DAYTIME HEATING IMPORTANT FOR SVR POTENTIAL. AS OF NOW...ALL SIGNS
POINT TO THIS BOUNDARY BEING WELL EAST OF THE CWA BY DAYTIME
HEATING.

FOR MONDAY AND THE REST OF THIS LONG TERM FCST PERIOD...PERSISTENCE
BECOMES A GOOD FORECAST THROUGH MID-WEEK. AN UPPER LEVEL TROUGH OVER
THE NORTHEASTERN US AND AN UPPER LEVEL RIDGE OVER THE MOUNTAIN WEST
WILL KEEP THE DMX CWA IN NORTHWESTERLY FLOW SEEMING INTO THE NEXT
THU/FRI/SAT TIMEFRAME. A HUGE THERMAL RIDGE WILL BUILD OVER THE
MOUNTAIN WEST COINCIDENT WITH THE UPPER LEVEL HIGH. THE RIDGE WILL
STAY TO OUR WEST AND 850 MB TEMPS WILL BE IN THE DMX CWA WILL BE
AROUND 15C TO OUR EAST AND 18C TO THE WEST. MODELS HINTING AT
THERMAL RIDGE CRASHING DOWN INTO IA SOMETIME LATER IN THE
WEEK...BRINGING A RETURN TO POP CHANCES TO THE AREA.

&&

.AVIATION...26/00Z
ISSUED AT 650 PM CDT THU JUN 25 2015

THERE WILL BE A BRIEF BREAK IN THE MVFR CIGS BUT AN UPPER LEVEL WAVE
WILL PUSH INTO IA LATE EVENING AND OVERNIGHT THROUGH FRIDAY MORNING
LOWERING CIGS ONCE AGAIN AND BRINGING SOME SCT SHRA/TSRA TO MOST TAF
LOCATIONS.  SFC FLOW WILL REMAIN GENERALLY AOB 10KTS OUT OF A N TO
NE DIRECTION.

&&

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

$$

SHORT TERM...PODRAZIK
LONG TERM...KOTENBERG
AVIATION...FAB



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