Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 041743
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1243 PM CDT TUE AUG 4 2015

.SYNOPSIS...
ISSUED AT 320 AM CDT TUE AUG 4 2015

GORGEOUS EARLY MORNING IN PROGRESS WITH COMFORTABLY COOL
TEMPS... LIGHT WINDS AND MAINLY CLEAR SKIES ALL COMPLIMENTS OF
SPRAWLING RIDGE OF HIGH PRESSURE FROM THE UPPER MIDWEST THROUGH
THE OHIO VALLEY. TEMPS AT 2 AM RANGED FROM THE MID 50S IN THE
VALLEYS AND FAVORED DRAINAGE LOCATIONS NORTH TO THE LOWER 60S
SOUTH... ROUGHLY SOME 5-10 DEGS BELOW NORMAL. REGIONAL RADAR
IMAGERY SHOWS CONVECTION EXTENDING FROM PORTIONS OF SD THROUGH
EASTERN NE...FAR SOUTHWEST IA AND NORTHERN MO ALONG 850 MB
CONVERGENCE AXIS WITH AID OF WEAK DISTURBANCES PROPAGATING DOWN
IN NORTHWEST FLOW ALOFT. ADDITIONAL CONVECTION WAS NOTED
SLIDING SEWD INTO PORTIONS OF SOUTHERN PLAINS AHEAD OF SHORTWAVE
TROUGH. MAIN FEATURE OF NOTE IS STRONGER SHORTWAVE OVER WY
EARLY THIS AM. THIS SYSTEM WILL EMERGE INTO THE PLAINS LATER TDY
THEN SLIDE E/SE PASSING MAINLY SOUTH OF THE AREA LATER WED... BUT
CLOSE PROXIMITY FOR RAIN CHANCES DEVELOPING ACROSS THE SOUTHERN
CWA.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 320 AM CDT TUE AUG 4 2015

ANOTHER GREAT SUMMER DAY IS ON TAP FOR THE REGION AS HIGH PRESSURE
SLOWLY TRAVERSES THE AREA... PROVIDING NEAR TO SLIGHTLY BELOW
NORMAL TEMPS WITH HIGHS AROUND 80 OR LOWER 80S AND LOW HUMIDITY.
WINDS TO BE LIGHTER TDY WITH THE HIGH OVERHEAD. OTHERWISE MUCH OF
THE AREA SUNNY TO MOSTLY SUNNY WITH JUST SOME THIN CIRRUS.
EXCEPTION WILL BE FAR SOUTHERN SECTIONS WHERE MAY SEE PERIODS OF
THICKER CIRRUS AND POSSIBLY MID CLOUDS BEING IN CLOSER PROXIMITY
TO THE CONVECTION. DID KEEP SOME SMALL POPS FAR SOUTHWEST CWA
FOR MAINLY LATER TDY... BUT OVERALL ISENTROPIC LIFT ON 320K SFC
AND ELEVATED CONVERGENCE ZONE WHILE DRIFTING EASTWARD A BIT LATER
TODAY (AS RIDGING BEGINS TO SLIDE EAST) REMAINS FOCUSED TO OUR WEST
AND SOUTH.

TONIGHT...SLOWLY SPREAD LOWER CHANCE POPS NORTHWARD WITH SOME
LIFTING NORTHWARD OF WEAK ISENTROPIC LIFT AND ELEVATED CONVERGENCE
ZONE... WITH PRECIP CHANCES MAINLY SOUTH OF CID TO MLI. OTHERWISE...
GENERALLY ANOTHER PLEASANT NIGHT WITH LOWS COOLEST NORTH/NORTHEAST
(50S) WHERE SKIES MAINLY CLEAR AND DRIER LOW LEVEL AIR WHILE
WARMER SOUTH (60-65) DUE TO CLOUDS AND SOME UPTICK IN MOISTURE.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 320 AM CDT TUE AUG 4 2015

MAIN FORECAST CONCERNS FOR THE LONG TERM ARE A LOW AND VORT MAX THAT
MOVES TO THE SOUTH OF THE AREA IN THE BEGINNING OF THE PERIOD AND
THE SUSTAINED NW FLOW AND THE WAVES TRANSVERSING THE FLOW.
CURRENTLY IT LOOKS AS THOUGH THE NEXT COUPLE OF DAYS WILL BE DRY
WITH THE EXCEPTION OF THE SOUTHERN CWA. LATER IN THE
PERIOD...SUBSTANTIAL DIFFERENCES BETWEEN GUIDANCE REMAIN AT THE END
OF THE PERIOD...AS A RESULT....SUPERBLEND HAS SLIGHTS TO CHC POPS
THROUGH THE EXTENDED.

WEDNESDAY THROUGH THURSDAY AM...

LARGE AMPLITUDE RIDGE TO OUR NORTHWEST WILL CONTINUE TO PUSH DRIER
AIR INTO THE AREA ALONG WITH SFC HIGH PRESSURE OVER THE GRT LAKES.
THIS WILL INEVITABLY KEEP THE SFC FLOW OUT OF THE EAST.  A DECENT
SHORTWAVE TROF IS TRANSVERSING BELOW THE HIGH AMPLITUDE RIDGE ACROSS
THE NE PANHANDLE TONIGHT.   AFTER THIS TIME THE MODELS DIFFER IN
SOLUTIONS.  THE GFS SEEMS TO BE THE MOST UNREASONABLE AS IT TRIES TO
FORCE THE WAVE HEADSTRONG INTO THE NW FLOW AND THEN DIVE SOUTH.
THIS SOLUTION PRODUCES DECENT PRECIP FOR OUR AREA.  I BELIEVE THIS
IS WRONG AND THAT THE 12Z AND 00Z ECMWF HAS A MUCH BETTER HANDLE ON
THIS STORM.  THE WAVE SHOULD INTERACT WITH THE NW FLOW AND DIVE
SOUTH. THIS WILL KEEP CYCLOGENESIS AND THE OVERALL PRECIP MAINLY
SOUTH OF I80 WITH THE BEST CHANCES BEING SOUTH OF HWY 34. 12Z WPC
GUIDANCE ALSO SUPPORTS THIS NOTION. AS A RESULT OF THIS AND THE
EASTERLY FLOW...THE ELEVATED WARM FRONT WILL STRUGGLE TO MOVE INTO
THE AREA BEFORE IT IS USHERED QUICKLY TO THE SOUTH AND THE EAST.
NORTH OF THE AREA...ANOTHER WAVE MOVES THROUGH THE FLOW. THIS WAVE
WILL ALSO PRODUCE PRECIP...BUT KEEP MOST OF IT NORTH OF THE AREA
IF NOT COMPLETELY OUT OF AREA. IF YOU ARE LOOKING FOR RAIN...THIS
IS NOT A GOOD WEEK SO FAR.

THURSDAY PM AND LATER...

YET ANOTHER WAVE IN THE FLOW IS PROG TO MOVE ACROSS SOUTHERN CANADA.
THIS WAVE APPEARS TO BE MORE ROBUST AND WILL LEAD TO CYCLOGENESIS TO
OUR NORTH.  THE LOW AND ATTENDANT BOUNDARIES SHOULD MOVE THROUGH
THE AREA FRIDAY.  THE BEST CHANCE FOR POPS WILL BE ACROSS NORTHERN
ZONES AS THE BETTER CONVERGENCE WILL BE ACROSS THE AREA.  THE GFS
DEVELOPS A SECOND SFC LOW....THIS SEEMS UNREASONABLE.  AFTER THIS
PERIOD NW FLOW BECOMES ENTRENCHED ACROSS THE AREA AGAIN AND WILL
LIKELY LEAD TO MORE WAVES IN THE FLOW.  THERE ARE DIFFERENCES IN THE
MODEL SOLUTIONS WHICH...LIKE LAST NIGHT...LEADS TO SCHC TO LOW CHC
POPS THROUGH THE REST OF THE EXTENDED.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1232 PM CDT TUE AUG 4 2015

SHOWERS AND THUNDERSTORMS MOVING ACRS NORTHERN MO/FAR
SOUTHEASTERN IA INTO WEST CENTRAL IL SHOULD STAY TO THE SOUTH OF
THE BRL TAF SITE THIS AFTERNOON. OTHERWISE EXPECT RATHER LIGHT
WEST WINDS OF 4-7 KTS AND VFR LEVEL DEBRIS CLOUDS THIS AFTERNOON
AND EARLY EVENING. MORE OF THE SAME TONIGHT INTO EARLY WED MORNING...
WITH MORE SHOWERS AND STORMS POSSIBLY GETTING TOWARD THE SOUTHERN
VCNTY OF BRL BUT WILL KEEP OUT MENTION FOR NOW. SOME CLOUD DECKS
MAY LOWER CLOSE TO MVFR AROUND BRL AS WELL LATE TONIGHT AND WED
MORNING IF SHOWERS GET A MORE NORTHERLY PUSH...BUT FOR NOW WILL
KEEP THEM SOUTH OF THE TAF SITES.    ..12..

&&

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

$$

SYNOPSIS...M^2
SHORT TERM...M^2
LONG TERM...GIBBS
AVIATION...12



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