000
FXUS63 KDMX 151712
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1212 PM CDT WED MAY 15 2013

.SHORT TERM.../TODAY /...
ISSUED AT 359 AM CDT WED MAY 15 2013

SURFACE HIGH PRESSURE WILL MOVE INTO THE STATE
TODAY AND WILL PROVIDE A MUCH QUIETER DAY ACROSS THE FORECAST
AREA. THERE IS A SMALL POTENTIAL FOR SOME VERY HIGH BASED
SHOWERS AND A STRAY THUNDERSTORM ACROSS NORTHERN IOWA THIS
MORNING...DUE TO SOME WEAK THETA-E ADVECTION AND FORCING BETWEEN
700-500MB. HRRR HAS THE ISOLATED SHOWERS THROUGH 18Z...BUT 00Z NMM
WRF DIMINISHING THE SHOWER ACTIVITY BEFORE ENTERING THE STATE.
LEANED TOWARD THE HRRR AS IT SEEMED TO HAVE A DECENT GRASP ON
CURRENT RADAR TRENDS.

WEAK BOUNDARY ACROSS SOUTHERN IOWA LOOKS TO BE A FOCAL POINT FOR
SOME ISOLATED THUNDERSTORMS THIS AFTERNOON. AGAIN...VERY HIGH BASED
AS VERY MINIMAL MOISTURE BELOW 700MB.

MAX TEMPS TODAY A LITTLE TRICK AS THINK GUIDANCE IS TOO LOW AGAIN
AND FELT CONFIDENT ENOUGH TO TWEAK TEMPS UP TODAY...ESPECIALLY
ACROSS THE SOUTH WHERE THE COOLER AIR DOES NOT REACH THIS AREA
UNTIL THE AFTERNOON. WENT ABOVE GUIDANCE ACROSS THE CENTRAL TO
SOUTHERN PORTIONS OF THE FORECAST AREA...WHICH WAS FAIRLY CLOSE TO
THE MAV MOS GUIDANCE. IN NORTHERN IOWA WENT CLOSER THE THE NAM/MET
MOS GUIDANCE FOR MAX TEMPS.

.LONG TERM.../TONIGHT THROUGH TUESDAY/...
ISSUED AT 359 AM CDT WED MAY 15 2013

RELATIVELY ACTIVE PERIOD THROUGH THE EXTENDED. HIGH PRESSURE WILL
GRADUALLY DEPART TONIGHT INTO THURSDAY AND AS IT DOES...A STALLED
FRONTAL BOUNDARY OVER NORTHERN MISSOURI WILL BEGIN TO LIFT BACK
NORTH INTO IOWA. AS THIS OCCURS...A PLUME OF MOISTURE LIFTING
THROUGH OKLAHOMA AND KANSAS WILL ARRIVE INTO SRN IA. THIS WILL
BRING BACK THE CHANCE FOR THUNDERSTORMS IN THAT REGION. A STRONG
PV ANOMALY OVER SRN NEVADA WILL APPROACH IA LATE THURSDAY AND
THURSDAY NIGHT. PREFER THE FARTHER NORTH NAM/ECMWF SOLUTION OVER
THE LESS ORGANIZED AND FARTHER SOUTH GFS. THIS WOULD PLACE THE
FOCUS FOR ADDITIONAL THUNDERSTORMS OVER NORTHWEST AND NORTH
CENTRAL IOWA. THIS POPS CONTINUE INTO FRIDAY MAINLY OVER THE
NORTH. EXPECT AT THIS POINT THAT POPS MAY BE OVERDONE FOR FRIDAY.
HAVE BEGUN TO TRIM BACK OVER THE CENTRAL AND SOUTH BUT IT MAY VERY
WELL BE MOSTLY DRY MOST LOCATIONS. THE SAME CAN BE SAID FOR FRIDAY
NIGHT WHERE POPS HAVE BEEN DROPPED FOR ALL BUT THE FAR NORTHEAST.

IOWA WILL BE IN THE WARM SECTOR ON SATURDAY AND WHILE LOW POPS
REMAIN...THE CONVECTIVE INHIBITION SHOULD HOLD STRONG MUCH OF THE
DAY. THE PRECIPITATION CHANCES THROUGH THE REMAINDER OF THE PERIOD
ARE MORE COMPLEX. THE INITIAL WAVE TO MOVE INTO THE INTER MOUNTAIN
WEST WILL BE FOLLOWED BY ANOTHER INTENSE PIECE OF ENERGY SATURDAY
NIGHT INTO SUNDAY. LONG RANGE GUIDANCE IS BEGINNING TO FAVOR THE
TWO TO MERGE AND FORM A CLOSED LOW TO THE WEST/NORTHWEST OF THE
AREA. THE FIRST WAVE WILL NUDGE THE UPPER LEVEL RIDGE ENOUGH EAST
SATURDAY NIGHT TO BRING A RETURN FOR PRECIPITATION
CHANCES...MAINLY OVER THE NORTH HOWEVER THE EVOLUTION TO A CLOSE
LOW WILL SLOW THE BOUNDARY ARRIVAL TO LATER SUNDAY INTO MONDAY.
INCREASING SOUTHWEST FLOW OVER THE STATE WILL KEEP THE PERIOD
ACTIVE AND EVENTUALLY SHOULD BRING A SEVERE WEATHER THREAT TO THE
STATE. TEMPERATURES THROUGH THE PERIOD WILL GENERALLY BE ABOVE
SEASONAL VALUES. COOLER ACROSS THE SOUTH ON THURSDAY DUE TO
ENHANCED CLOUD COVER THEN WARMER AGAIN FRIDAY INTO SATURDAY.

&&

.AVIATION...15/18Z
 ISSUED AT 1209 PM CDT WED MAY 15 2013

CEILINGS WILL REMAIN VFR FOR PERIOD AT SITES WITH HIGH PRESSURE
BUILDING IN. WINDS WILL BE GUSTY IN THE AFTERNOON WITH
MIXING...BUT WILL REMAIN BELOW 20KTS. BOUNDARY NEAR SOUTHERN IOWA
WILL BE FOCUS FOR ISOLATED RA/TSRA DEVELOPMENT IN THE AFTERNOON.
MAY SEE SOME TSRA AT SOUTHERN SITES...KDMS/KOTM...BUT HAVE NOT
INCLUDED MENTION ATTM WITH SCATTERED NATURE OF RA. WINDS WILL
DECREASE AFTER 00Z...BECOMING MORE EASTERLY.

&&

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

&&

$$

SHORT TERM...PODRAZIK
LONG TERM...DONAVON
AVIATION...AWB