000
FXUS63 KDMX 040824
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
323 AM CDT SAT JUL 4 2009

.SHORT TERM /TODAY/...
UPPER LEVEL DISTURBANCE MOVING THROUGH THE REGION NOW...EXPECTED TO 
DROP EAST SOUTHEAST OF THE STATE BY LATE TODAY...ALLOWING FOR PRECIP 
TO DIMINISH ACROSS THE AREA THROUGHOUT THE DAY. FAIRLY DECENT AREAL 
COVERAGE ACROSS THE CWA...WITH THIS TREND EXPECTED TO CONTINUE TO 
WIDESPREAD LIFT HANGING INTO THE MID MORNING HOURS. MAINLY LIGHT 
SHOWERS...BUT A LINE OF THUNDERSTORMS MOVING ACROSS PORTIONS OF 
CENTRAL AND SOUTH CENTRAL IOWA SHOULD CONTINUE TO BRING MODERATE TO 
HEAVY RAIN AT TIMES THROUGH THE NEXT FEW HOURS. RAINFALL AMOUNTS 
HAVE MAINLY RANGES FROM AROUND A TENTH TO HALF AN INCH...BUT HAVE 
SEEN MUCH HIGHER REPORTS FROM SITES BENEATH THE HEAVIER BAND OF RAIN 
STRETCHING FROM NEAR ATLANTIC TO OSCEOLA SOUTHEASTWARD. THIS BAND 
SHOULD CONTINUE TO PROGRESS SLOWLY EASTWARD WITH TIME THROUGH THE 
MID MORNING HOURS...ALLOWING WIDESPREAD AMOUNTS OF AT LEAST A HALF 
AN INCH TO AN INCH ACROSS THE SOUTHERN CWA. OTHERWISE PRECIP TO 
TAPER OFF THIS AFTERNOON AS SYSTEM HEADS TOWARD THE OHIO VALLEY. 
WITH CLOUDS/PRECIP ACROSS MUCH OF THE AREA TODAY...EXPECT LITTLE 
RECOVERY IN TEMPS. THEREFORE WENT A LITTLE COOLER THAN PREVIOUS 
GRIDS...WITH HIGHS MAINLY IN THE LOW TO MID 70S. 

.LONG TERM /TONIGHT THROUGH FRIDAY/...
HIGH PRESSURE BUILDS IN TONIGHT...AND WHEN THE SKY CLEARS OUT THERE 
IS THE GOOD POSSIBILITY FOR FOG TO DEVELOP UNDER THE RIDGE. WILL NOT 
MENTION IN THE FORECAST YET...BUT IT IS SOMETHING TO WATCH FOR LATER 
SHIFTS. THE NEXT ISSUES APPEAR RELATIVELY MINOR...BUT UNDER AN 
UNUSUALLY MOIST NORTHWESTERLY FLOW PATTEN AND A WEAK BACKDOOR FRONT 
MOVING SOUTH AND SOUTHWEST INTO THE REGION LATE SUNDAY INTO 
MONDAY...CANNOT JUSTIFY KEEPING THE FORECAST COMPLETELY DRY 
EVERYWHERE. IT IS GOING TO BE DIFFICULT TIMING THE INDIVIDUAL 
SHORTWAVES THAT COULD ENHANCE CONVECTIVE POTENTIAL...BUT IT SEEMS 
THAT ONE WILL BE MOVING TOWARD NW IA LATE SUNDAY...THEN ANOTHER ONE 
MOVING THROUGH MONDAY. A NARROW CORRIDOR OF MODEST INSTABILITY WITH 
LITTLE INHIBITION DEVELOPS SUNDAY AFTN NW INTO CENTRAL SECTIONS. 
HOWEVER...DEEP LAYER SHEAR ON THE WEAK END. SAME THING MONDAY AFTN 
THOUGH A LITTLE FARTHER SOUTH AND WEST. THE GFS TRIES TO BRING AN 
MCS THROUGH WRN/CENTRAL AREAS EARLY MONDAY...BUT THIS IS NOT 
SUPPORTED BY PREVIOUS RUNS...SO WILL DISCOUNT THAT SCENARIO AT THIS 
TIME. THE CONVECTIVE POTENTIAL SUNDAY AND MONDAY APPEAR MORE 
DIURNALLY DRIVEN...WITH LITTLE CHANCES FOR CONVECTION AFTER 
MIDNIGHT. WILL KEEP TUESDAY DRY FOR NOW...BUT CHANCES FOR 
THUNDERSTORMS RETURN BY WEDNESDAY ACROSS THE NORTH...ON THE EDGE OF 
THE CAP AND CLOSER TO FORCING. CHANCES SPREAD SOUTH LATE IN THE WEEK 
AS A FRONT PUSHES SOUTH. OTHERWISE...TEMPERATURES WILL BE CLIMBING 
BACK TO NEAR NORMAL.
 
&&

.AVIATION...04/06Z
APPROACHING WAVE OVERNIGHT...SHRA/TSRA ACTIVITY FROM KS AND NE WILL 
EXPAND NORTH AND EAST INTO IOWA...THOUGH AS THE STORMS MOVE INTO 
MORE STABLE AIRMASS...THUNDER CHANCES WILL BE MUTED NORTH THOUGH 
RAINFALL WILL STILL BE PERSISTENT AND CIGS/VISBYS EXPECTED TO DROP 
TO IFR RANGE AFTER SEVERAL HOURS OF RAIN. THUNDER WILL CONTINUE OVER 
THE SOUTH AND WILL MAINTAIN EITHER VCTS OR TSRA IN KDSM AND KOTM 
TAFS OVERNIGHT. ALL IN ALL...CONDITIONS SHOULD SLOWLY IMPROVE ON 
SATURDAY AS THE SYSTEM TRANSLATES EAST. WE WILL HAVE MVFR CIGS AND 
POTENTIAL REDUCTION IN VSBYS DURING THE MORNING HOURS FOLLOWING THE 
RAIN. THOUGH WIDESPREAD RAINFALL EXPECTED OVERNIGHT...MUCH OF THE 
AREA WILL HAVE STRATIFORM PRECIP...ESPECIALLY OVER THE NORTHERN 
SECTIONS. 

&&

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

&&

$$

SHORT TERM...ALBRECHT
LONG TERM...MOYER
AVIATION...REV