Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 070902
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
402 AM CDT THU MAY 7 2015

.SYNOPSIS...
ISSUED AT 339 AM CDT THU MAY 7 2015

FRONTAL BOUNDARY FROM ERN ND INTO THE TEXAS PANHANDLE WILL MOVE
EAST AND REACH SOUTHEAST IOWA BY FRIDAY MORNING BEFORE STALLING.
FRONT WILL BEGIN LIFTING NORTH SATURDAY AND SATURDAY NIGHT IN
RESPONSE TO A STRONG S/WV LIFTING OUT OF THE WESTERN TROUGH. LOW
WILL MOVE THROUGH NORTHWEST IOWA WITH TRAILING COLD FRONT
SWEEPING THROUGH THE STATE BY MONDAY MORNING. COOL HIGH PRESSURE
WILL DOMINATE THE FIRST PART OF NEXT WEEK.

&&

.SHORT TERM /TODAY/...
ISSUED AT 339 AM CDT THU MAY 7 2015

AREA OF WEAKENING CONVECTION OVER WESTERN IOWA THIS MORNING WITH
LIGHTNING ASSOCIATED WITH THE ACTIVITY BECOMING MORE SPARSE OVERALL.
ANOTHER WAVE OF THETA-E ADVECTION WILL LIFT INTO SOUTHERN IOWA BY
EARLY THIS MORNING AND IS EXPECTED TO BE THE FOCUS FOR RENEWED
SHOWERS AND THUNDERSTORMS AND LIFT NORTHEAST THROUGH THE STATE. HI
RESOLUTION SOLUTIONS SUGGESTING A LULL IN THE ACTIVITY EARLY THIS
AFTERNOON. A WEAKENING BOUNDARY WILL ENTER NORTHWEST IOWA AND WILL
SHIFT VERY SLOWLY SOUTHEAST THROUGH THE DAY INTO TONIGHT. MOISTURE
TRANSPORT REMAINS GOOD DURING THE DAY WITH THE LOW LEVEL JET OF 35
TO 40 KTS SHIFTING EAST OVER THE STATE. THIS WILL PUSH PWAT VALUES
TO 1.25-1.50 INCHES. WARM CLOUD DEPTHS AT LESS THAN 10 KFT NOT
FAVORABLE FOR HEAVY RAINFALL HOWEVER WITH PWATS CLIMATOLOGICALLY
HIGH AND STORM MOTIONS FAVORABLE NEARLY PARALLEL TO THE INSTABILITY
AXIS COULD LEAD TO NUMEROUS STORMS OVER THE SAME AREA AND INCREASE
THE THREAT. BY MID TO LATE AFTERNOON...THUNDERSTORM CHANCES WILL BE
GREATEST OVER THE FAR SOUTHEAST NEAR THE MOISTURE TRANSPORT AXIS AND
TO THE NORTHWEST IN VICINITY OF THE SURFACE BOUNDARY. AN ISOLATED
SEVERE STORM OR TWO AREA POSSIBLE. MELTING LEVEL HEIGHTS ARE
RELATIVELY LOW WITH INCREASING CAPE VALUES IN THE -10C TO -30C LAYER.

.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
ISSUED AT 339 AM CDT THU MAY 7 2015

THUNDERSTORMS FROM THE DAY WILL CONTINUE TO BE SQUEEZED EAST
TONIGHT AS THE FRONTAL BOUNDARY MOVES EAST. WITH THE FRONT
STALLING SOUTH OF THE STATE AND A NELY FLOW OF SOMEWHAT DRIER
AIR...MOST OF THE ACTION WILL BE SOUTHEAST OF IOWA FRIDAY AND
FRIDAY NIGHT.

ATTENTION TURNS TO THE WEEKEND WELL ADVERTISED SITUATION WITH A
CLOSED LOW LIFTING OUT OF THE SOUTHWEST U.S. SURFACE LOW IS SLATED
TO MOVE THROUGH NORTHWEST IA SUNDAY NIGHT. ECMWF HAS BEEN
CONSISTENT WITH THIS TRACK AND OTHER DETERMINISTIC MODELS ARE ON
BOARD WITH A VERY SIMILAR TRACK THOUGH THERE ARE SOME SIGNIFICANT
DIFFERENCES WITH THE SYSTEM THIS WEEKEND...LOOKING AT CIPS
PRODUCTS INDICATE THE 05/27/95 EVENT IS QUITE SIMILAR IN MANY
WAYS. ECMWF IS THE MOST AGGRESSIVE AND PRESENTS A CLASSIC TRIPLE
POINT AND DRY LINE EVENT. SUNDAY AND SUNDAY EVENING IS LIKELY TO
UNFOLD AS A SIGNIFICANT OUTBREAK DAY. CAPE VALUES ARE NOT
TREMENDOUSLY HIGH...BUT OTHER KINEMATICS ARE CERTAINLY IN PLACE.

ONCE THE LOW PASSES...A SHARP CHANGE TO COOLER WEATHER FOR THE
FIRST PART OF NEXT WEEK. SHOWERY ON MONDAY YET...BUT MUCH COOLER
WITH HIGHS IN THE 50S AND 60S FOR A COUPLE DAYS.



&&

.AVIATION...07/06Z
ISSUED AT 1157 PM CDT WED MAY 6 2015

AREA OF SHOWERS AND STORMS WILL PROGRESS INTO WESTERN IOWA
OVERNIGHT AND EVENTUALLY ACROSS CENTRAL IOWA THROUGH THURSDAY
MORNING. WHILE CONDITIONS WILL BE PRIMARILY VFR...LOCATIONS
EXPERIENCING SHOWERS AND STORMS WILL SEE MVFR TO LOCALIZED IFR
CONDITIONS WITH RESTRICTIONS TO CEILINGS AND VISIBILITIES. WILL
SEE THE VFR CONDITIONS IN MOST LOCATIONS BY MIDDAY INTO THE
AFTERNOON ON WEDNESDAY BEFORE MORE CONVECTION DEVELOPS IN THE AREA
ON WEDNESDAY LATE AFTERNOON AND EVENING.


&&

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

$$

SYNOPSIS...MS MAY 15
SHORT TERM...DONAVON
LONG TERM...MS MAY 15
AVIATION...COGIL



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