Flash Flooding and Damaging Winds in Iowa, July 5 to 6, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
653 AM 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. ISENTROPICUPGLIDE
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...05/12Z
ISSUED AT 653 AM CDT SUN JUL 5 2015

VFR CONDITIONS EXPECTED THROUGHOUT MUCH OF THE PERIOD. INITIALLY
MAY HAVE A BRIEF VSBY REDUCTION AT KOTM WITH LIGHT FOG...OTHERWISE
CLOUDS TO INCREASE THROUGH THE DAY AHEAD OF AN AREA OF LOW
PRESSURE APPROACHING FROM THE NORTHWEST. A FRONTAL BOUNDARY WITH
PUSH THROUGH LATE TONIGHT INTO MONDAY WITH CHANCES FOR
PRECIPITATION. HAVE HIGHLIGHTED WITH VCSH AT KFOD AND KMCW.
BEST CHANCES FOR THE OTHER STATIONS WILL BE BEYOND THE CURRENT
FORECAST PERIOD. SOUTHERLY WINDS TO INCREASE ACROSS THE AREA TODAY
AND THEN LOSE THE GUSTINESS THIS EVENING...BUT REMAIN SOMEWHAT UP
OVERNIGHT.

&&

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

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
407 AM CDT SUN JUL 5 2015

IAZ004>007-015>017-023>025-033>035-044-045-060915-
EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO-
POCAHONTAS-HUMBOLDT-WRIGHT-SAC-CALHOUN-WEBSTER-CRAWFORD-CARROLL-
407 AM CDT SUN JUL 5 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

WIDESPREAD THUNDERSTORMS ARE POSSIBLE LATE TONIGHT INTO MONDAY.
MODERATE TO HEAVY RAIN IS EXPECTED WITH THE STORMS. A FEW STRONG
TO SEVERE STORMS MAY OCCUR WITH DAMAGING WIND AND LARGE HAIL THE
PRIMARY THREATS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

NUMEROUS THUNDERSTORMS ARE LIKELY MONDAY. MODERATE TO HEAVY
RAIN IS EXPECTED WITH THE STORMS. A FEW STRONG TO SEVERE STORMS
PRODUCING DAMAGING WINDS AND LARGE HAIL WILL BE POSSIBLE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATE NIGHT AND MONDAY.

IAZ026>028-036>039-046>050-057>062-070>075-081>086-092>097-060915-
FRANKLIN-BUTLER-BREMER-HAMILTON-HARDIN-GRUNDY-BLACK HAWK-GREENE-
BOONE-STORY-MARSHALL-TAMA-AUDUBON-GUTHRIE-DALLAS-POLK-JASPER-
POWESHIEK-CASS-ADAIR-MADISON-WARREN-MARION-MAHASKA-ADAMS-UNION-
CLARKE-LUCAS-MONROE-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE-
APPANOOSE-DAVIS-
407 AM CDT SUN JUL 5 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

WIDESPREAD THUNDERSTORMS ARE LIKELY MONDAY. MODERATE TO HEAVY
RAIN IS EXPECTED WITH LOCALIZED FLOODING POSSIBLE. A FEW STRONG
TO SEVERE STORMS MAY OCCUR PRODUCING DAMAGING WINDS AND LARGE
HAIL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED MONDAY.