Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 041718
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1218 PM CDT FRI SEP 4 2015

.UPDATE...
ISSUED AT 1217 PM CDT FRI SEP 4 2015

VERY SMALL SHOWERS HAVE BEEN POPPING UP IN EASTERN HENRY AND
BUREAU COUNTIES IN IL THIS MORNING ALONG THE EDGE OF CAP ALOFT AND
A WEAK LOW LEVEL BOUNDARY EVIDENT IN THE SURFACE WIND FIELDS AND
VISIBLE SATELLITE FROM N CENTRAL IL INTO NE IA. HAVE UPDATED THE
FORECAST FOR THESE ISOLATED SHOWERS IN THE EAST...WHICH COULD
INTENSIFY TO ISOLATED THUNDERSTORMS...WHICH WERE ALREADY IN THE
FORECAST IN THIS AREA FOR THIS AFTERNOON.

AREA OBSERVATIONS THIS MORNING SHOWED TEMPERATURES HEATING UP
AT A FASTER RATE THAN YESTERDAY MORNING. WITH A SIMILAR THERMAL
PROFILE ALOFT AND INITIALLY MOSTLY SUNNY SKIES OVER ALL BUT THE
FAR EAST...HIGHS SHOULD BE SIMILAR TO PERHAPS A FEW DEGREES WARMER
THAN YESTERDAY AND HAVE MADE UPWARD TWEAKS IN THE FORECAST.
DEWPOINTS IN THE UPPER 60S TO LOWER 70S MAY PUSH THE HEAT INDEX TO
NEAR 100 IN SOME LOCATIONS.

&&

.SYNOPSIS...
ISSUED AT 310 AM CDT FRI SEP 4 2015

SURFACE LOW OVER MICHIGAN THIS MORNING...WITH WEAK TRAILING SURFACE
TROUGH ACROSS NORTHERN ILLINOIS AND IOWA.  ALOFT...UPPER RIDGE SPANS
CENTRAL U.S. FROM MINNESOTA TO TEXAS.  ELEVATED ISOLATED STORMS
PERCOLATING OVER NORTHWESTERN PARTS OF THE CWFA THIS MORNING IN AREA
OF WARM ADVECTION.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 310 AM CDT FRI SEP 4 2015

ISOLATED STORMS THIS MORNING IN NORTHWEST PARTS OF THE AREA WILL
CONTINUE TO SHRINK IN COVERAGE THROUGH SUNRISE.

WITH RESPECT TO THE HEAT...HEAT CONTINUES TODAY AS UPPER RIDGE
SLOWLY BUILDS INTO EASTERN IOWA.  DEW POINTS NEAR 70 WILL GUARANTEE
A WARM START TO THE DAY AND AMPLE SUNSHINE WILL RESULT IN A QUICK
WARMUP WITH TEMPERATURES ACROSS MUCH OF THE CWFA APPROACHING 90 BY
NOON.  SHOULD SEE SEVERAL HOURS THROUGH THE AFTERNOON WITH HEAT
INDICES IN THE MID TO UPPER 90S.

WITH RESPECT TO POTENTIAL FOR ADDITIONAL STORMS TODAY...MICHIGAN
SURFACE LOW AND ASSOCIATED TROUGH WILL WASH OUT AS THE UPPER SUPPORT
WEAKENS. IN THE MEANTIME...THERE REMAINS A LOW CHANCE FOR SHOWERS OR
WEAK THUNDERSTORMS TO DEVELOP ALONG THE RATHER DIFFUSE BOUNDARY OVER
FAR EASTERN PORTIONS OF THE AREA WITH PEAK HEATING THIS AFTERNOON.
THUS HAVE MAINTAINED LOW POPS THIS AFTERNOON AND EVENING FROM JO
DAVIESS COUNTY TO BUREAU COUNTY.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 310 AM CDT FRI SEP 4 2015

HOT AND HUMID TO START THE LABOR DAY WEEKEND...THEN TURNING
ACTIVE WITH THE POTENTIAL FOR A FEW ROUNDS OF SHOWERS AND
STORMS SUNDAY NIGHT THROUGH THE FIRST HALF OF NEXT
WEEK...FOLLOWED BY COOLER AND DRIER CONDITIONS.

UPPER RIDGE WILL RE-AMPLIFY OVER THE CENTRAL CONUS TO BEGIN THE
LABOR DAY WEEKEND AHEAD OF UPPER LEVEL ENERGY MOVING THROUGH THE
WEST. BUILDING HEIGHTS ALOFT WILL PRECLUDE DEEP CONVECTION ON
SAT... BUT STILL LOW POTENTIAL FOR SHALLOW/WEAK ISOLATED PM
SHOWERS AND STORMS WITH CONVECTIVE TEMPS BREACHED... ESPECIALLY
NORTH/EAST CWA WITHIN LINGERING MID LEVEL MOIST AXIS.
OTHERWISE... LITTLE CHANGE IN AIRMASS WITH H85 TEMPS AROUND 20-21C
BOTH DAYS SUPPORTS GENERAL PERSISTENCE FOR HIGHS IN THE UPPER 80S
TO LOWER 90S BOTH SAT/SUN WITH PM HEAT INDEX VALUES MOSTLY IN THE
LOWER TO MIDDLE 90S. BY SUNDAY NIGHT... RAIN CHANCES LOOK TO BE ON
THE INCREASE ESPECIALLY WEST OF THE MISSISSIPPI RIVER... AS DEEP
MOISTURE AIDED BY ACTIVE MONSOON INTERACTS WITH AN APPROACHING COLD
FRONT AND WEAK HEIGHT FALLS OVERSPREAD AREA ALOFT AS AN UPPER LEVEL
DISTURBANCE LIFTS FROM THE NORTHERN ROCKIES INTO SOUTHERN CANADA.
ANY STORMS WILL LIKELY BE HEAVY RAIN PRODUCERS WITH SEVERAL MODELS
SHOWING PWATS IN EXCESS OF 2 INCHES AHEAD OF THE FRONT.

MONDAY THROUGH WEDNESDAY... GENERAL SCENARIO OF FRONT STALLING IN
OR NEAR SOUTHERN CWA EARLY IN WEEK SEEMS PLAUSIBLE AS BOUNDARY
BECOMES PARALLEL TO MID LEVEL FLOW... AND AS WEAK HEIGHT FALLS
BEGIN TO OVERSPREAD THE REGION AHEAD OF NEXT WESTERN SHORTWAVE TROUGH.
THIS TROUGH IS GENERALLY SHOWN TO PASS AROUND MIDWEEK... AND
UNTIL DOING SO... THE AREA WILL STAND POTENTIAL FOR ACTIVE/UNSETTLED
PERIOD OF WEATHER MON-WED WITH A FEW ROUNDS OF SHOWERS AND STORMS WITH
VACILLATING FRONT AND ANY SMALL PERTURBATIONS EJECTING FROM SOUTHWEST
MONSOON AHEAD OF MAIN TROUGH MIDWEEK. DEEP MOISTURE IS SHOWN TO POOL
YET AGAIN WITH PWATS OVER 2 INCHES... THUS CONTINUED POTENTIAL FOR HEAVY
RAIN.

LATE WEDNESDAY THROUGH FRIDAY...COOLER AND DRIER CONDITIONS GENERALLY
FAVORED AS LARGE COOL CANADIAN HIGH PRESSURE BUILDS INTO THE REGION.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1217 PM CDT FRI SEP 4 2015

A WEAK BOUNDARY OVER NE IA INTO NORTHERN IL WILL CONTINUE TO
TRIGGER ISOLATED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND
OVERNIGHT. THIS ARE MOST LIKELY TO BE CONFINED TO AREAS EAST OF
MLI THIS AFTERNOON...BUT COULD POSSIBLY IMPACT THE TERMINALS LATE
TONIGHT. AT THIS TIME...THE POTENTIAL FOR THIS IS TOO LOW TO
MENTION IN THE FORECASTS. OTHERWISE...VFR CONDITIONS WILL CONTINUE
WITH A VERY WARM AND HUMID AIRMASS AND LIGHT SURFACE WINDS SHOWING
PRIMARILY A SOUTHERLY COMPONENT.

&&

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

$$

UPDATE...SHEETS
SYNOPSIS...DMD
SHORT TERM...DMD
LONG TERM...MM
AVIATION...SHEETS


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