Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 051741
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1241 PM CDT SUN JUL 5 2015

.SHORT TERM /TODAY/...
ISSUED AT 256 AM CDT SUN JUL 5 2015

HIGH PRESSURE HAS SHIFTED OFF TO THE SOUTHEAST WITH AN AREA OF LOW
PRESSURE APPROACHING THE REGION CENTERED ACROSS THE NORTHERN HIGH
PLAINS. THIS AREA OF LOW PRESSURE WILL SHIFT ESE TODAY BECOMING
CENTERED OVER CENTRAL SD/NE BY LATE TODAY. SOUTHERLY FLOW WILL
INCREASE AHEAD OF IT WITH THE SFC PRES GRADIENT TIGHTENING ACROSS
IOWA. THIS WILL CREATE BREEZY CONDITIONS BY THIS AFTERNOON...AND WAA
WILL ALLOW FOR TEMPS TO PUSH INTO THE MID TO UPPER 80S ACROSS THE
CWA TODAY. AN AREA OF THUNDERSTORMS HAS DEVELOPED OFF TO THE
NORTHWEST OF THE CWA...WITH THE ACTIVITY EXPECTED TO SLOWLY PUSH
EAST AND DIMINISH THROUGH SUNRISE. THEREFORE EXPECT DRY CONDITIONS
TO HOLD ON FOR TODAY...WITH INCREASING CLOUD COVER AS MOISTURE
INCREASES ALOFT AS WELL.

.LONG TERM /TONIGHT THROUGH FRIDAY/...
ISSUED AT 256 AM CDT SUN JUL 5 2015

FORECAST FOCUS IS ON POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS
PRODUCING HEAVY RAIN LATE TONIGHT THROUGH MONDAY. AN UPPER TROUGH
DIGGING INTO THE NORTHERN PLAINS WILL DRIVE A SURFACE COLD FRONT
SOUTHEAST THROUGH THE CORN BELT. THIS FRONT WILL INTERACT WITH A
MOIST BOUNDARY LAYER WITH PRECIPITABLE WATER VALUES PROGGED NEAR
2 INCHES. NUMEROUS SHOWERS AND THUNDERSTORMS WILL DEVELOP NEAR AND
ALONG THIS FRONT AS THE FRONT APPROACHES NORTH CENTRAL IOWA EARLY
MONDAY MORNING. THE FRONT WILL CONTINUE TO MOVE THROUGH THE STATE
AND EXIT SOUTHEAST IOWA BY EARLY TUESDAY MORNING. FORECAST MODELS
PROG 0-3 KM BULK SHEAR NEAR 35 TO 45 KNOTS BRINGING A RISK FOR
DAMAGING WINDS. AHEAD OF THE FRONT...DAYTIME HEATING WILL AID
INSTABILITY WITH MODELS DEPICTING MU CAPE NEAR 2000 J/KG MONDAY
AFTERNOON. LAPSE RATES WILL BE SUFFICIENT FOR A MARGINAL HAIL
RISK. HEAVY RAIN WILL BE REALIZED WHERE STRONGER UPDRAFTS
MATERIALIZE WITH LOCALIZED FLASH FLOODING POSSIBLE DUE TO HIGH
RAINFALL RATES AND WHERE SHOWERS AND THUNDERSTORMS TRACK OVER THE
SAME LOCATIONS.

BEHIND THE DEPARTING COLD FRONT...SURFACE HIGH PRESSURE WILL
BUILD ACROSS THE MIDWEST BRINGING A COOLER AND DRIER AIRMASS TO
THE REGION. HIGH TEMPERATURES TUESDAY AND WEDNESDAY WILL BE 10 TO
15 DEGREES BELOW NORMAL HIGH TEMPERATURES FOR THIS TIME OF THE
YEAR.

MID WEEK THE SURFACE HIGH WILL BUILD TO THE EAST BRINGING THE
RETURN OF SOUTHERLY FLOW TO IOWA AND A WARMING TREND. ISENTROPIC UPGLIDE
WILL BE SUPPORTIVE OF SLIGHT CHANCES FOR SHOWERS AND THUNDERSTORMS
WEDNESDAY NIGHT ACROSS SOUTHERN IOWA.

THERE IS GENERAL AGREEMENT BETWEEN FORECAST MODELS OF AN UPPER
RIDGE STRENGTHENING OVER THE SOUTHERN PLAINS. SHORTWAVES MOVING
UP AND OVER THE RIDGE THROUGH THE CORN BELT WILL PROVIDE
ADDITIONAL CHANCES FOR SHOWERS AND THUNDERSTORMS LATE IN THE WEEK.

&&

.AVIATION...05/18Z
ISSUED AT 1241 PM CDT SUN JUL 5 2015

VFR CONDITIONS WILL CONTINUE TO BE WIDESPREAD THIS AFTERNOON AND
TONIGHT AS BOUNDARY DRIFTS TOWARD THE STATE. ANY CEILINGS WILL
REMAIN AT OR ABOVE 12KFT WITH SOUTH SURFACE WINDS STATEWIDE.
TOWARD DAYBREAK ON MONDAY...CONVECTION IS EXPECTED TO MOVE INTO
NORTHERN IOWA AND SINK GRADUALLY SOUTHWARD THROUGH THE END OF THE
PERIOD. KFOD AND KMCW HAVE THE BEST CHANCES OF SEEING
THUNDERSTORMS PRIOR TO THE END OF THE PERIOD. ELSEWHERE...VFR
CONDITIONS WILL CONTINUE TO PREVAIL.

&&

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

&&

$$

SHORT TERM...BEERENDS
LONG TERM...ANGLE
AVIATION...COGIL



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