Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 172353
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
653 PM CDT SUN AUG 17 2014

.SYNOPSIS...
ISSUED AT 331 PM CDT SUN AUG 17 2014

RATHER QUIET CONDITIONS WERE IN PLACE ACROSS THE AREA THIS
AFTERNOON AS REGION IS IN A LULL BETWEEN WEATHER SYSTEMS. THE LOW
THAT BROUGHT RAIN INTO THE FAR SOUTH YESTERDAY WAS OVER FAR
SOUTHERN IL. UPSTREAM...AN UPPER LOW WAS OVER SOUTHERN
SASKATCHEWAN WITH A SHORTWAVE OUT AHEAD OVER MN PRODUCING
SCATTERED SHOWERS AND THUNDERSTORMS AS CLOSE AS N CENTRAL IA. IN
BETWEEN...SHORTWAVE RIDGING AND A LOW LEVEL EASTERLY FLOW OUT OF A
SURFACE HIGH OVER NORTHERN LAKE SUPERIOR WAS PROVIDING SLIGHTLY
BELOW NORMAL TEMPERATURES WHILE ABUNDANT LOW LEVEL MOISTURE WAS
KEEPING WIDESPREAD LOW CLOUDS AND SOMEWHAT HAZY CONDITIONS IN
PLACE OVER THE REGION.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 331 PM CDT SUN AUG 17 2014

INITIAL CONCERN IS THE RETURN OF FOG TONIGHT...THEN THE POTENTIAL
FOR SHOWERS AND THUNDERSTORMS MONDAY AS A SHORTWAVE IN THE DAKOTAS
MOVES THROUGH. THE WEAK SURFACE RIDGE AXIS EXTENDING SOUTHWEST FROM
THE UPPER GREAT LAKES INTO IA WILL PROVIDE VERY LIGHT EASTERLY WINDS
OVERNIGHT. CONSIDERING THIS...NEUTRAL FORCING ALOFT...AND THE
SIMILAR AIRMASS IN PLACE...FOG IS LIKELY TO REFORM TONIGHT. WILL
THUS GO WITH PATCHY FOG OVER THE ENTIRE AREA BY MIDNIGHT...
INCREASING TO AREAL WORDING ALONG AND EAST OF THE MS RIVER TOWARD
MORNING. A DENSE FOG ADVISORY MAY AGAIN BE NEEDED FOR THIS AREA.
LOW TEMPERATURES SHOULD BE SIMILAR TO THIS MORNING...FROM THE
UPPER 50S NORTHEAST TO THE MID 60S SOUTH.

MONDAY...ANY FOG SHOULD DISSIPATE BY MID MORNING...AND THE
ASSOCIATED LOW CLOUDS WILL LIKELY BURN OFF QUICKER GIVEN THE
DEVELOPING SOUTHWEST LOW LEVEL SURFACE WINDS AHEAD OF THE SHORTWAVE
APPROACHING FROM THE NORTHWEST. WILL KEEP A SLIGHT CHANCE FOR
NOCTURNALLY INITIATED STORMS IN THE FAR NW IN THE MORNING. BETTER
CHANCES WILL BE IN THE NORTHERN HALF OF THE FORECAST AREA DURING THE
AFTERNOON AS THE SHORTWAVE PASSING ALONG THE IA/MN BORDER...AND A
FOLLOWING STRONGER WAVE APPROACHING THE UPPER MS SPREAD MID LEVEL
FORCING OVER THE REGION. A LINGERING WEAK LAKE ENHANCED BOUNDARY MAY
PROVIDE THE INITIAL FOCUS FOR DEVELOPMENT OF STORMS THAT MAY BE
CAPABLE OF STRONG GUSTY WINDS AND SMALL HAIL DUE TO SUFFICIENT MID
DEEP SHEAR BUT BORDERLINE CAPE VALUES. WHILE THE HIGH PW VALUES
MAY LEAD TO HEAVY RAINFALL RATES...HEAVY RAINFALL AMOUNTS DO NOT
LOOK TO BE AN ISSUE DUE TO THE MORE PROGRESSIVE NATURE OF THE
STORMS THAN SEEN OVER THE REGION THE PAST FEW DAYS. HIGHS SHOULD
BE A FEW DEGREES WARMER THAN TODAY AS WARM ADVECTION DEVELOPS ON
THE LOW LEVEL SW FLOW.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 331 PM CDT SUN AUG 17 2014

OPERATIONAL MODELS HAVE DONE A COMPLETE REVERSAL COMPARED TO
YESTERDAY AND INSTEAD OF A HIGHLY AMPLIFIED OMEGA BLOCK THEY NOW
SHOW A MORE ACTIVE ZONAL FLOW. THIS DOESN`T HELP WITH CONFIDENCE.

MONDAY NIGHT AND TUESDAY...UPPER LEVEL TROUGH CURRENTLY LOCATED IN
SOUTHERN SASKATCHEWAN WILL BE DIVING SOUTHEAST INTO THE MIDWEST
EARLY IN THE WEEK. DIFFLUENCE ALOFT IS NOTED BY THE MODELS AND THIS
WILL BE ACCOMPANIED BY A WEAK COLD FRONT WHICH WILL HELP FOCUS
CONVECTION. WILL CONTINUE WITH LIKELY POPS ACROSS OUR NORTHERN CWA
CLOSER TO THE BETTER FORCING...ESPECIALLY MONDAY NIGHT.

WEDNESDAY THROUGH THURSDAY...HEIGHTS BEGIN TO BUILD ALLOWING FOR
HEAT AND HUMIDITY TO SURGE NORTHEAST IN THE FORM OF A STRONG WARM
FRONT LIFTING INTO THE REGION. A VERY WARM AND UNSTABLE BUT LIKELY
CAPPED ATMOSPHERE WILL BE SOUTH OF THE FRONT...WITH POTENTIALLY
WIDESPREAD THUNDERSTORMS DEVELOPING MAINLY WEDNESDAY NIGHT. THIS IS
WHERE IT GETS TRICKY BECAUSE ANY LEFTOVER CLOUDS FROM THE MCS MAY
SPILL INTO THURSDAY WHICH MAY IMPACT TEMPERATURES. FOR NOW THE GRIDS
WILL INDICATE MAXIMUM TEMPERATURES WELL INTO THE 80S TO AROUND 90.

FRIDAY THROUGH SUNDAY...OPERATIONAL MODELS INDICATE THE HEAT AND
HUMIDITY WILL BE OVER THE CWA FRIDAY THROUGH SATURDAY WITH THE
POTENTIAL FOR ANOTHER MCS FRIDAY NIGHT. THIS TO BE FOLLOWED BY A
STRONG COLD FRONT BY SUNDAY WITH MORE THUNDERSTORMS. A SHARP TROUGH
THEN DIVES INTO THE MIDWEST DURING THE LAST WEEK OF AUGUST WITH
BELOW NORMAL TEMPERATURES.

HAASE

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 646 PM CDT SUN AUG 17 2014

GENERALLY VFR CONDITIONS EXPECTED THIS EVENING. ABUNDANT MOISTURE
AND LIGHT WINDS WILL AGAIN RESULT IN DETERIORATING CONDITIONS
OVERNIGHT TO MVFR AND IFR WITH POCKETS OF VLIFR IN FOG AND LOW
CLOUDS. THE LOWEST CONDITIONS APPEAR TO FAVOR ALONG AND EAST OF
THE MISSISSIPPI RIVER. GRADUAL IMPROVEMENT TO MVFR THEN VFR
EXPECTED MONDAY MID AM THROUGH EARLY AFTN. WILL SEE A CHANCE OF
SHOWERS AND STORMS BY MID TO LATE AFTN AHEAD OF A COLD FRONT
WITH BEST RAIN CHANCES BEING ALONG AND NORTH OF I-80. WINDS
THROUGH EARLY MONDAY AM WILL BE LIGHT E/SE THEN SHIFT TO S/SW AND
INCREASE AROUND 10 KTS DURING AFTN WITH SOME LOCAL GUSTS 15-18 KTS
POSSIBLE.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...SHEETS
SHORT TERM...SHEETS
LONG TERM...HAASE
AVIATION...05





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