Area Forecast Discussion
Issued by NWS Des Moines, IA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KDMX 280007
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
707 PM CDT SAT JUN 27 2015

.SHORT TERM /TONIGHT/...
ISSUED AT 301 PM CDT SAT JUN 27 2015

MAIN CHALLENGE TONIGHT WILL BE THE EXTENT AND TIMING OF THE THUNDER
LATER THIS EVENING. EARLY AFTERNOON SFC ANALYSIS SHOWS A POCKET OF
SFC MOISTURE OVER EASTERN IOWA AND SOME MOISTURE CONVERGENCE IN
EASTERN NEBRASKA ALONG A WARM FRONT WHICH WILL BUBBLE UP A FEW
STORMS THIS AFTERNOON. A FEW ISOLATED THUNDERSTORMS MAY OCCUR OVER
THE EAST YET PRIOR TO 00Z...BUT SHOULD DIMINISH/FALL APART AT
SUNSET. MODELS IN GOOD AGREEMENT WITH WARM AIR ADVECTION ALONG THE
TROUGH OVER NORTHERN MINNESOTA/NORTH DAKOTA INITIATING AN AREA OF
THUNDERSTORMS THIS AFTERNOON...CONTINUING SOUTHEAST THIS EVENING AND
OVERNIGHT AS THE H500 WAVE AND VORTICITY ADVECTION TRACKS SOUTHEAST
INTO IOWA AFTER 06Z. INTENSITY WILL LESSEN AS THE STORMS CROSS INTO
IOWA LATER THIS EVENING...BUT COVERAGE WILL EXPAND A BIT ALONG THE
BOUNDARY AS BULK SHEAR INCREASES ACROSS THE REGION AFT 06Z. HAVE
KEPT MOST AREAS WITH POP...BEST CHANCES OVER THE NORTHEAST/EAST
THROUGH 12Z. FOR NOW...LOWERED THUNDER CHANCES TO SCT THOUGH MAY
SEE MORE ISO THUNDER OVERNIGHT IF INSTABILITY WANES. LOWS WILL
REMAIN IN THE LOWER TO MID 60S ACROSS THE BOARD WITH LIGHT SW
WINDS AHEAD OF THE SYSTEM BECOMING MORE WESTERLY BY 12Z.

.LONG TERM /SUNDAY THROUGH SATURDAY/...
ISSUED AT 301 PM CDT SAT JUN 27 2015

IOWA WILL REMAIN BENEATH NORTHWESTERLY FLOW ALOFT AT LEAST THROUGH
FRIDAY...RESULTING IN OVERALL COOL WEATHER WITH INTERMITTENT
PRECIPITATION CHANCES AS SHORTWAVE TROUGHS MOVE THROUGH THIS FLOW.
THE FIRST SUCH DISTURBANCE WILL CROSS THE REGION ON SUNDAY WITH AN
ATTENDANT SURFACE COOL FRONT PUSHING THROUGH OUR FORECAST AREA
DURING THE DAYTIME. IN THE MORNING WINDS WILL COME AROUND TO
SOUTHWEST AHEAD OF THE BOUNDARY AND A COMBINATION OF MODERATE
DIURNAL HEATING AND DEWPOINTS IN THE LOWER 60S OR SO SHOULD
RESULT IN DECENT INSTABILITY IN OUR SOUTHERN AND EASTERN COUNTIES
AS THE FRONT PUSHES THROUGH IN THE AFTERNOON. COMBINED WITH DEEP
LAYER SHEAR OF AROUND 30 TO 40 KNOTS THIS SHOULD BE SUFFICIENT
FOR SOME STRONG TO SEVERE STORMS AND SPC HAS PLACED ABOUT THE
SOUTHEAST HALF OF OUR AREA IN A MARGINAL RISK...WITH A SLIGHT RISK
ACROSS THE FAR SOUTHEAST CORNER OF IOWA AND DOWN INTO MISSOURI.
THIS IS VERY REASONABLE...BUT WITHIN OUR FORECAST AREA THE SEVERE
THREAT SHOULD BE PRETTY SHORT LIVED AND CONFINED MAINLY TO SOUTH
AND EAST OF THE DES MOINES METRO AREA WHERE LARGE HAIL AND STRONG
WINDS WILL BE POSSIBLE.

SUCCESSIVE IMPULSES MOVING THROUGH THE NORTHWESTERLY FLOW WILL
GENERATE ADDITIONAL RAIN CHANCES AROUND MONDAY AFTERNOON AND
EVENING...FROM TUESDAY NIGHT THROUGH WEDNESDAY...AND THEN AGAIN
AROUND THURSDAY. AT THIS TIME IT APPEARS THAT INSTABILITY AND ANY
SEVERE WEATHER THREAT WILL BE QUITE LIMITED...HOWEVER ON WEDNESDAY
AFTERNOON WHEN THE SECOND OF THESE SYSTEMS PUSHES THROUGH AN
ACCOMPANYING WEAK SURFACE LOW SHOULD ORGANIZE SOMEWHERE AROUND
NORTHEASTERN KANSAS WITH A MODEST SURFACE FRONT EXTENDING ACROSS
NORTHERN MISSOURI...AND THIS COULD BE A CATALYST FOR SOME SEVERE
WEATHER POTENTIAL THAT MAY JUST SNEAK INTO FAR SOUTHERN IOWA. AT
THIS TIME IT IS MORE LIKELY THAT ANY SUCH THREAT WOULD BE SOUTH OF
THE BORDER HOWEVER.

FROM WEDNESDAY THROUGH AT LEAST SATURDAY THE COMBINATION OF
GENERALLY LIGHT NORTHWEST FLOW...COOL HIGH PRESSURE SYSTEMS...AND
PERIODS OF CLOUD COVER/RAIN SHOULD KEEP TEMPERATURES FAIRLY LOW
WITH HIGHS GENERALLY IN THE MID 70S TO LOWER 80S. HOWEVER...BY
NEXT WEEKEND OR EARLY THE FOLLOWING WEEK THE 500 MB FLOW SHOULD
FINALLY BEGIN TO FLATTEN OUT AND GO MORE WEAKLY ZONAL...ALLOWING
TEMPERATURES TO SLOWLY REBOUND TOWARD SEASONAL NORMALS.

&&

.AVIATION...28/00Z
ISSUED AT 705 PM CDT SAT JUN 27 2015

MAIN CONCERNS ARE CIG AND VSBY DEGRADATIONS DUE TO PERIODS OF
CONVECTION LATE TONIGHT INTO SUN. NOTHING BEYOND SCT/BKN MID
CLOUDS THROUGH THE EVENING...BUT ATTENTION WILL TURN TO
SHOWERS/STORMS APPROACHING FROM THE NW LATE TONIGHT. ALTHOUGH
THERE IS SOME MINIMAL POTENTIAL FOR MVFR OR LOWER WITH THE
PASSAGE OF CONVECTION...PREDOMINATE CATEGORY SHOULD REMAIN VFR
THROUGH THE PERIOD. WINDS SHOULD GO FROM LIGHT AND VARIABLE THIS
EVENING...TO LIGHT SLY OVERNIGHT...AND EVENTUALLY TO NW BY SUN
AFTERNOON WITH WEAK FRONTAL PASSAGE.

&&

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

&&

$$

SHORT TERM...REV
LONG TERM...LEE
AVIATION...SMALL



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.