Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 282048
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
348 PM CDT FRI AUG 28 2015

.SYNOPSIS...
ISSUED AT 339 PM CDT FRI AUG 28 2015

APPROACHING UPPER LEVEL DISTURBANCE AND LOW TO MID LEVEL WARM
MOIST ADVECTION AIDING WIDESPREAD COVERAGE OF SHOWERS AND
SOME STORMS FROM NORTH CENTRAL INTO NORTHEAST IA AT MID AFTN
WITH MORE WIDELY SCATTERED ACTIVITY FURTHER SOUTH. SLOW MOVING
BAND OF CONVECTION NEARLY ANCHORED WEST TO EAST IMMEDIATELY
AHEAD OF VORT MAX WITHIN ZONE OF STRONG MOISTURE TRANSPORT
(PWATS OF 1.7-1.8+ INCHES) WHICH IS LEADING TO LOCALIZED SWATH
OF VERY HEAVY RAIN 3-5+ INCHES AND SOME FLASH FLOODING OVER NORTH
CENTRAL NOW ADVANCING INTO NORTHEAST IA. THIS SLOW MOVING SYSTEM
WILL LOOK TO BRING INCREASING RAIN CHANCES TO MUCH OF CWA TONIGHT
(HEAVY RAIN PORTIONS OF NORTHEAST IA) WITH THE RAIN LINGERING
INTO SATURDAY WHILE GRADUALLY SHIFTING EASTWARD.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 339 PM CDT FRI AUG 28 2015

RAIN CHANCES WILL CONTINUE TO EXPAND AND INCREASE TONIGHT AS SLOW
MOVING DISTURBANCE MOVES INTO THE REGION. GREATEST RAIN CHANCES
WILL BE FOUND IMMEDIATELY AHEAD OF MID LEVEL WAVE OR ROUGHLY
ALONG/N OF HWY 30... ALTHOUGH DO ANTICIPATE INCREASE IN COVERAGE
TONIGHT FURTHER SOUTH. FAIRLY HIGH WARM CLOUD DEPTHS AND PWATS
INCREASING TO OVER 1.7 TO 1.8 INCHES WILL BRING LIKELIHOOD OF HIGH
RAINFALL EFFICIENCY...WITH AREAS NEAR/NORTH OF HWY 30 AND
ESPECIALLY ON IA SIDE FAVORED FOR HEAVIEST RAINS BEING IMMEDIATELY
AHEAD OF MID LEVEL WAVE AND REMAINING IN VEERED LOW LEVEL JET AND
MOISTURE TRANSPORT THE LONGEST. IN SOME OF THESE AREAS NEAR/N OF
HWY 30 COULD SEE LOCALLY 2-3+ INCHES AND POTENTIAL FOR LOCALIZED
FLASH FLOODING ISSUES WITH CONVECTION AND HIGHER RATES ALONG WITH
SLOW MOVEMENT. WITH CLOUDS AND SOUTHERLY WINDS HAVE STAYED NEAR
BLEND OR WARM SIDE OF GUIDANCE FOR LOWS... AND HAVE RANGE FROM
AROUND 60 NORTH TO MID 60S SOUTH.

SATURDAY...WILL SEE GRADUAL ENDING OF RAIN CHANCES FROM WEST TO
EAST DURING DAY... WITH EVEN SOME DECREASE IN CLOUDS WEST OF THE
MISSISSIPPI BY MID TO LATE PM. HIGHS WILL BE CHALLENGING AND
DEPENDENT ON AMOUNT OF SUNSHINE... AND GENERALLY HAVE MID 70S TO
AROUND 80 DEGS WITH WARMEST READINGS LIKELY BEING FOUND OVER
WESTERN PORTIONS OF CWA.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 339 PM CDT FRI AUG 28 2015

OVERVIEW...BUILDING AND PERSISTENT UPPER-LEVEL RIDGE OVER THE
CENTRAL U.S. WILL LEAD TO ABOVE AVERAGE TEMPERATURES AND HUMID
CONDITIONS THROUGH THE EXTENDED PERIOD. OVERALL CHANCES FOR RAIN
ARE VERY LOW.

SATURDAY NIGHT THROUGH SUNDAY...HAVE 20 POPS EARLY SATURDAY NIGHT
ALONG AND EAST OF THE MISSISSIPPI RIVER...NOTHING WIDESPREAD IS
EXPECTED AND MOST AREAS WILL STAY DRY AS UPPER DISTURBANCE EXITS TO
THE EAST. ON SUNDAY...LOWER 80S ON AVG FOR HIGHS AND PARTLY SUNNY
SKIES WILL MAKE FOR A NICE END TO THE WEEKEND.

MONDAY AND TUESDAY...EXPECT WARMER TEMPS INTO THE MIDDLE/UPPER 80S
AS UPPER-LEVEL RIDGE BUILDS OVER THE MIDWEST. 1000-500MB THICKNESS
VALUES ARE FORECAST TO HOVER NEAR 576 DAM AND 850MB TEMPS NEAR 18 C.

WEDNESDAY...A SHORTWAVE TROUGH FROM REMNANT MONSOONAL CONVECTION
MAY TRAVERSE THE MIDWEST BUT PLENTY OF UNCERTAINTY AS TO WHETHER
THIS FEATURE EVEN DEVELOPS. INTRODUCED SLIGHT CHANCES FOR SHOWERS
AND THUNDERSTORMS. NO SIGNIFICANT CHANGE IN 1000-500MB THICKNESSES
OR 850MB TEMPS MEANS HIGHS SHOULD STILL AVG IN THE MID/UPPER 80S.

THURSDAY AND FRIDAY...MODELS INDICATE A SLIGHT UPTICK IN 850MB TEMPS
TOWARD 20C. CURRENT FORECAST HAS UPPER 80S ON AVG ACROSS THE CWA.
RAW MODELS SUCH AS THE ECMWF/GFS ARE IN THE LOWER TO MIDDLE 90S BUT
FEEL THIS IS TOO WARM GIVEN 850MB TEMPS AT 20C OR LOWER...HUMID SFC
CONDITIONS WITH DEWPOINTS IN THE UPPER 60S...AND A LOWER SEPTEMBER
SUN ANGLE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1255 PM CDT FRI AUG 28 2015

STORM SYSTEM OVER IA WILL SHIFT EAST TOWARD LAKE MICHIGAN BY THE
END OF THE TAF CYCLE. THIS SYSTEM WILL BRING WIDESPREAD
RAIN/SHOWERS TO AREAS NORTH OF I-80...WITH PERIODIC BANDS OF
SHOWERS SOUTH OF I-80. ISOLD STORMS WILL ALSO BE POSSIBLE.
CONDITIONS WILL GENERALLY RANGE FROM VFR TO MVFR IN THE
PRECIPITATION...WITH ISOLD IFR VSBYS POSSIBLE IN STRONGER SHOWERS
AND ISOLD STORMS. TONIGHT...WILL CONTINUE WITH WIDESPREAD RAIN
OR SHOWERS NORTH OF I-80 AND PERIODIC BANDS OF SHOWERS SOUTH OF
I-80... WITH GENERALLY VFR TO MVFR CONDITIONS. WITH CONTINUED
MOISTENING AND BL COOLING AND LIGHT WINDS DO ANTICIPATE
DEVELOPMENT OF MORE WIDESPREAD MVFR TO IFR CONDITIONS IN LOW
CLOUDS AND FOG OVERNIGHT AND SATURDAY AM...ESPECIALLY WEST OF THE
MISSISSIPPI RIVER.

&&

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

$$

SYNOPSIS...MCCLURE
SHORT TERM...MCCLURE
LONG TERM...UTTECH
AVIATION...MCCLURE



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