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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
638 AM CDT TUE JUN 30 2015

.SHORT TERM /TODAY/...
ISSUED AT 351 AM CDT TUE JUN 30 2015

IOWA REMAINS IN ESTABLISHED NORTHWEST FLOW ALOFT WITH BAROCLINIC 
ZONE SETTING UP ALONG THE MISSOURI RIVER VALLEY TODAY.  WARM 
ADVECTION ACROSS THE DAKOTAS ALONG THIS TIGHTENING GRADIENT ALREADY 
PRODUCING SOME SHOWERS AND THUNDERSTORMS OVERNIGHT. A WEAK WAVE 
MOVING ALONG THE BAROCLINIC ZONE WILL HELP FOCUS LOW LEVEL 
CONVERGENCE INTO WESTERN IOWA BY LATER THIS AFTERNOON ALONG WITH MID 
LEVEL LIFT WHICH WILL SUPPORT SCATTERED THUNDERSTORMS ACTIVITY BY 
LATER THIS AFTERNOON. HAVE INCLUDED LOW POPS IN THE FAR WEST BY MID 
AFTERNOON AS CONVECTION EXPANDS INTO THE AREA ALTHOUGH THE BEST 
THREAT FOR CONVECTION WILL BE INTO TONIGHT. OTHERWISE...CLOUDS WILL 
BE ON THE INCREASE WITH THE APPROACHING SHORTWAVE IN ADDITION TO 
SOME SMOKE FROM THE CANADIAN FIRES DRIFTING OVERHEAD.  THIS SHOULD 
IMPACT TEMPERATURES WITH READINGS HOLDING BELOW NORMAL INTO THE 
AFTERNOON. 

.LONG TERM /TONIGHT THROUGH MONDAY/...
ISSUED AT 351 AM CDT TUE JUN 30 2015

THE UPPER MIDWEST WILL REMAIN IN A GENERAL NORTHWEST FLOW UNTIL WELL 
PAST THE EXTENDED FORECAST PERIOD.  THIS WILL BRING SEASONAL 
TEMPERATURES AND TOLERABLE HUMIDITIES TO THE REGION BUT WE WILL ALSO 
BE SUSCEPTIBLE TO EVERY SHORTWAVE RIDING THROUGH THE FLOW.  THE 
FIRST SHORTWAVE WILL IMPACT THE SOUTHWEST HALF OF THE STATE TONIGHT 
INTO WEDNESDAY BRINGING A CHANCE FOR SHOWERS AND THUNDERSTORMS.  
WHILE WE ARE NOT LOOKING PARTICULARLY UNSTABLE...THERE IS SOME 
PRETTY IMPRESSIVE SHEAR MOVING ACROSS SOUTHWEST IOWA AND AS SUCH 
THERE WILL BE SOME THREAT OF STORMS BEING CAPABLE OF LARGE HAIL AND 
DAMAGING WIND...ESPECIALLY IN THE EVENING.  

THE MODELS ARE IN DECENT AGREEMENT WITH DROPPING ANOTHER SHORTWAVE 
ACROSS THE SOUTHWEST HALF OF THE STATE THURSDAY INTO FRIDAY BUT 
SHEAR IS ALMOST NON-EXISTENT AND INSTABILITY IS EVEN WEAKER THAN 
TODAY SO WHILE WE MAY SEE SOME SHOWERS AND THUNDERSTORMS WITH THIS 
SYSTEM THE THREAT OF SEVERE STORMS IS NOT IMPRESSIVE.  

THE PARADE OF SHORTWAVES WILL CONTINUE THROUGH THE HOLIDAY WEEKEND 
BUT OVERALL PRECIP CHANCES LOOK PRETTY LOW UNTIL LATE SUNDAY INTO 
MONDAY WHEN A FRONTAL BOUNDARY WILL CROSS IOWA COINCIDENT WITH YET 
ANOTHER SHORTWAVE. INSTABILITY WILL BE QUITE IMPRESSIVE AS THE FRONT 
MOVES THROUGH DURING PEAK HEATING AND THERE WILL BE SUFFICIENT SHEAR 
AS WELL SO SOME SEVERE STORMS CAN BE ANTICIPATED LATE SUNDAY AND 
MONDAY.  TEMPERATURES WILL ACTUALLY BE SEASONABLY COOL THROUGH 
FRIDAY WITH HIGHS FROM THE UPPER 70S TO MID 80S.  LOWER TO MID 80S 
ARE EXPECTED FOR THE MOST PART OVER THE WEEKEND.

&&

.AVIATION...30/12Z
ISSUED AT 638 AM CDT TUE JUN 30 2015

SMOKE FROM CANADIAN WILDFIRES WILL CONTINUE TO PRODUCE A HIGH
LEVEL HAZE LAYER ACROSS IOWA TODAY WITH INCREASING CLOUDS IN
WESTERN IOWA. SOME HAZE IS EXPECTED EARLY IN THE FORECAST BUT VFR
CEILINGS AND VISIBILITIES WILL BE MOST COMMON LATER TODAY INTO
TONIGHT. THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE
TONIGHT...ESPECIALLY IN WESTERN IOWA WITH MVFR TO IFR CONDITIONS
IN AND AROUND THUNDERSTORMS. WINDS WILL REMAIN QUITE VARIABLE
ACROSS THE STATE WITH A WEAK PRESSURE GRADIENT FOR MUCH OF THE
FORECAST PERIOD.

&&

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

&&

$$

SHORT TERM...COGIL
LONG TERM...FAB
AVIATION...COGIL

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