Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 301642
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1142 AM CDT SUN AUG 30 2015

.UPDATE...
ISSUED AT 1130 AM CDT SUN AUG 30 2015

VISIBILITIES IN THE FOG HAVE IMPROVED TO WELL ABOVE 1 MILE IN
NEARLY ALL AREAS...THUS THE DENSE FOG ADVISORY WAS ALLOWED
TO EXPIRE. LINGERING IS A STRATUS DECK ALTHOUGH SATELLITE LOOP
DEPICTS SOME DECREASE SOUTH OF I-80. DESPITE THIS...STILL SOME
MILKY CIRRUS ABOVE AND WITH LINGERING LOW LEVEL MOISTURE ANY
AREAS THAT SEE DECREASE IN STRATUS SHOULD DEVELOP SOME STRATOCU...
THUS REST OF TODAY BUMPED UP SKY COVER TO GENERAL PARTLY TO MOSTLY
CLOUDY. HIGH TEMPS QUITE CHALLENGING BUT OPTED TO LEAVE AS IS
(MID 70S NORTH TO LOW 80S SOUTH) FOR NOW DUE TO VARYING CLOUD
COVERAGE AND SATELLITE TRENDS SUGGESTING MORE PEAKS OF SUNSHINE
ESPECIALLY SOUTHERN CWA. ANTICIPATE MORE FOG AGAIN TONIGHT GIVEN
LITTLE CHANGE IN AIRMASS WITH ABUNDANT LOW LEVEL MOISTURE AND
WEAK LOW LEVEL FLOW... WITH MORE DENSE FOG POSSIBLE IN AREAS AND
FOR NOW HAVE UPDATED TO GO WITH AREAS OF FOG IN FORECAST LATE THIS
EVENING INTO MID AM MONDAY.

&&

.SYNOPSIS...
ISSUED AT 259 AM CDT SUN AUG 30 2015

HIGH PRESSURE WAS LOCATED OVER THE AREA THIS MORNING AS WIDESPREAD
AREAS OF DENSE FOG HAVE FORMED. THE MOST DENSE FOG APPEARS TO BE
ALONG AND WEST OF THE MISSISSIPPI RIVER INTO IOWA. VISIBILITIES OF
A QUARTER MILE AND LESS HAVE BEEN REPORTED ACROSS THIS AREA. AS A
RESULT...HAVE ISSUED A DENSE FOG ADVISORY FOR THE AREA UNTIL 11 AM
CDT SUNDAY. THIS FOG AND WHEN IT WILL BURN OFF WILL BE THE PRIMARY
WEATHER DRIVER TODAY AND EVEN INTO TONIGHT WHEN MORE FOG COULD
FORM ACROSS THE AREA.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 259 AM CDT SUN AUG 30 2015

MAIN FORECAST CONCERN OF THE DAY IS WHAT HAPPENS TO THE FOG THIS
AM AND WHAT THEN HAPPENS TO SUBSEQUENT HIGH TEMPS TODAY AND THEN
FOG REDEVELOPMENT TONIGHT ACROSS THE AREA. DENSE FOG ACROSS THE
AREA WILL LIKELY STAY ENTRENCHED THROUGH MOST OF THE MORNING
UNTIL A LIGHT WIND MAY BE ABLE TO IMPROVE THE VISIBILITIES ACROSS
THE AREA.

CONDITIONS REMAIN IN PLACE FOR DENSE FOG DEVELOPMENT AND
MAINTENANCE THIS MORNING. HIGH PRESSURE WAS LEADING TO THE
DEVELOPMENT OF A SUBSIDENCE INVERSION. LIGHT TO CALM WINDS TONIGHT
ALONG WITH CLEARING CLOUDS AND HIGH MOISTURE WAS LEADING TO FOG.
THROUGH THE EARLY SHORT TERM PERIOD THIS FOG LOOKS TO HOLD ON AS
WINDS WILL REMAIN LIGHT TO EVEN CALM MOST OF THE MORNING. FOG
BURNING OFF FROM SUNSHINE WILL BE THE DOMINANT FORCING TO REMOVE
FOG THIS AM. THERE IS A POSSIBILITY THAT FOG COULD PERSIST
AFTER NOON TODAY. AS A RESULT TEMPERATURES FOR TODAY ARE TRICKY TO
SAY THE LEAST. TEMPS WILL LIKELY BE COOLER THAN PREVIOUSLY
FORECAST. DECIDED TO GO WITH THE COOLER MET AND INCREASE TEMPS A
COUPLE OF DEGREES WHERE FOG HAS NOT DEVELOPED TONIGHT.

THIS EVENING...CALM WINDS AND HIGH PRESSURE WILL BE OVER THE AREA
AS WELL. AT THIS TIME I DO NOT HAVE ENOUGH CONFIDENCE TO GO WITH
ANYTHING MORE THAN PATCHY FOG. DO NOT THINK WE WILL SEE AS MUCH
DENSE FOG TONIGHT AS WE ARE SEEING RIGHT NOW. REGARDLESS FOG AND
TEMPS ARE THE MAIN FORECAST ISSUES IN THE SHORT TERM.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 259 AM CDT SUN AUG 30 2015

A PERIOD OF LATE SUMMER HEAT AND DRY OR MOSTLY DRY THIS UPCOMING
WEEK WITH ISOLATED AFTERNOON STORMS POSSIBLE.

LONG TERM FORECAST CONFIDENCE ASSESSMENT...GOOD OR ABOVE AVERAGE AS
STAGNANT RIDGING PATTERN TO PROVIDE LITTLE SENSIBLE WEATHER ISSUES
AS HAVE STATED THE PAST FEW NIGHTS.   MINOR ISSUES ARE THE SAME
WHICH IS TEMPERATURES MOST PERIODS BASED ON PERSISTENCE MAY BE A
DEGREE OR TWO TOO WARM BOTH FOR HIGHS AND POSSIBLY EVEN MORE SO FOR
MINS MOST PERIODS AND RISK OF ISOLATED SHOWER OR STORM AS CONVECTIVE
TEMPERATURES MAY BE REACHED MID TO LATE PM.

OVERVIEW...INITIALIZATION AND VERIFICATION AT 06Z ARE STRAIGHT-
FORWARD WITH LIMITED TRENDS AND IMPACTS IN STAGNANT LATE SUMMER
PATTERN.  BESIDES BL MOISTURE A BIT TOO MOIST...RUN TO RUN AND
FORCING TOOLS SUGGEST A EVEN MIX OF ALL SOLUTIONS WITH ONLY MINOR
DIFFERENCES.

MONDAY...MINOR CHANGES MADE.  MOSTLY FAIR SKIES BY MID MORNING
ONWARD AFTER SOME FOG.   THIS COMBINED WITH SOUTH WINDS AND RIDGING
AND SOUTH WINDS OF 5 TO 15 MPH SHOULD ALLOW HIGH TEMPERATURES TO
RISE INTO THE MID 80S MOST LOCATIONS AND SOME HEAT INDICES VALUES TO
AROUND 90F FOR A FEW HOURS.  DRY CONDITIONS WITH SOME FAIR WEATHER
CUMULUS CLOUDS AS CONVECTIVE TEMPERATURES SHOULD NOT BE REACHED.
MONDAY NIGHT...FAIR WITH LIGHT SOUTH WINDS SHOULD ALLOW FOR AT LEAST
PATCHY FOG ONCE AGAIN AND POSSIBLY MORE WIDESPREAD FOR LATER SHIFT
TO REASSESS.  LOWS SHOULD BE MOSTLY IN THE MIDDLE 60S.

TUESDAY THROUGH FRIDAY...ESSENTIALLY NO CHANGE IN FORECAST AS
STAGNANT RIDGING PATTERN CONTINUES WITH ABOVE NORMAL TEMPERATURES
AND HUMID.  HIGHS SHOULD BE 85 TO 90 DEGREES MOST LOCATIONS EACH DAY
WITH HEAT INDEX VALUES RISING IN PM INTO THE LOWER 90S.  ISOLATED
STORMS SEEM PROBABLE MOST DAYS AS CONVECTIVE TEMPERATURES WILL BE
VERY TO BEING REACHED.  ANY STORMS SHOULD BE NON-SEVERE BUT GUSTY
WINDS ARE POSSIBLE FOR LATER SHIFTS TO CONSIDER.  LOWS MOST NIGHTS
SHOULD BE IN THE MIDDLE 60S WITH SOME UPPER 60S POSSIBLE WITH AGAIN
PATCHY FOG MOST NIGHTS DUE TO LIGHT WINDS...LONGER NIGHTS AND FAIR
SKIES WITH OUR HIGH DEWPOINTS WELL INTO THE MID 60S.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 621 AM CDT SUN AUG 30 2015

LIFR TO MVFR AND VFR CONDITIONS ARE CURRENTLY FORECAST THROUGH THE
MORNING HOURS AT A FEW TAF SITES. A MVFR STRATUS DECK WAS MOVING
THROUGH BRL AND CID. THIS DECK WILL HELP TO ELIMINATE THE THREAT
OF DENSE FOG. MLI IS THE SITE WHERE DENSE FOG MAY PERSIST THE
LONGEST. AFTER THE MORNING...LIGHT WINDS AND VFR CONDITIONS ARE
EXPECTED. PATCHY FG WILL DEVELOP TONIGHT ACROSS THE AREA. I DONT
HAVE HIGH CONFIDENCE WHERE IFR OR LIFR VSBYS WILL OCCUR...SO
DECIDED TO TREND TOWARDS IT WITH 4SM BR. VSBYS WILL LIKELY BE
LOWER TONIGHT AND WILL REQUIRE FINE TUNING TODAY.

&&

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

$$

UPDATE...05
SYNOPSIS...GIBBS
SHORT TERM...GIBBS
LONG TERM...NICHOLS
AVIATION...GIBBS



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