Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 291912
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
212 PM CDT FRI AUG 29 2014

.SYNOPSIS...
ISSUED AT 1244 PM CDT FRI AUG 29 2014

A DEEP RICH MOISTURE PLUME CONTINUES TO FEED INTO EASTERN IOWA AND
MUCH OF THE UPPER MIDWEST. OUR CWA FELL WEST OF A FEW HEAVY RAIN
PRODUCING STORMS IN ILLINOIS EARLIER TODAY...AND UNDER A WEAK AREA
OF SUBSIDENCE THROUGH EARLY AFTERNOON. THIS HAS ALLOWED LOW LEVELS
TO HEAT UP UNINHIBITED. AS OF 1 PM...WIDESPREAD LOWER TO MID 80S ARE
FOUND OVER EASTERN IOWA AND WESTERN ILLINOIS...WITH DEWPOINTS IN THE
70 TO 73 RANGE. HIGHS TODAY SHOULD REACH THE MID TO UPPER 80S. CAPE
VALUES ESTIMATED BY SPC RAP AS OF 1 PM ARE 2000 TO 3000 OVER ALL OF
THE CWA. A VORTICITY MAXIMA IS LOCATED IN EASTERN KS...WITH A PVA
WING OF LIFT FOUND INTO CENTRAL MISSOURI. THIS IS ALREADY DEVELOPING
A LINE OF DEEP CONVECTION FROM NORTH CENTRAL TO SOUTH

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 1244 PM CDT FRI AUG 29 2014

THE VORT MAX TO THE SOUTHWEST WILL LIFT THROUGH IOWA THIS
EVENING...HELPING ORGANIZE STORMS AS THEY MOVE THROUGH THE CWA. FROM
LATE AFTERNOON THROUGH MID EVENING...THESE SHOULD IMPACT MUCH OF THE
CWA. A LACK OF SHEAR SHOULD DECREASE ANY WIDESPREAD SEVERE WEATHER
THREAT...BUT SOME ISOLATED WIND DAMAGE IS POSSIBLE THROUGH WET
MICROBURST ACTIVITY IN THE STRONGEST CELLS. OTHERWISE....THIS SHOULD
BE HEAVY RAIN PRODUCING LINE OF STORMS...WITH SOME BRIEF TRAINING
POSSIBLE. A WIDESPREAD RAIN OF 0.25 TO 0.75 IS EXPECTED...WITH
SWATHS OF 1 TO 2 INCHES. WE ARE LIKELY TO HANDLE THIS MINOR
FLOOD/URBAN RUNOFF THREAT WITH SPS PRODUCTS.

TONIGHT...STORMS SHOULD BECOME LESS NUMEROUS...AND POSSIBLY END
FULLY. HOWEVER...WITH THE PARENT VORT MOVING BY WITH AMPLE
MOISTURE...WE WILL LEAVE POPS GOING THROUGH THE NIGHT.
SATURDAY...MODELS BRING ANOTHER QUICK SHOT OF ENERGY THROUGH WHILE
MOISTURE IS DEPARTING. THIS MAY BRING SOME SHOWERS AND STORMS TO
ROUGHLY THE EAST HALF...BUT SHOULD SUBSIDENCE BECOME MORE CONFIDENT
BEHIND TONIGHTS STORMS...WE MAY BE DRY ALL DAY SATURDAY.

TEMPERATURES LOOK MILD TONIGHT...IN THE UPPER 60S...WHILE SATURDAY
SHOULD SEE A DRY AFTERNOON REBOUND TO THE UPPER 70S TO LOWER 80S.
CLOUDS WHILE THICK IN THE MORNING SHOULD BECOME SCATTERED BY MID
DAY.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 1244 PM CDT FRI AUG 29 2014

THE MAIN FORECAST CONCERN IN THE LONG TERM PERIOD IS STORM
COVERAGE/RAINFALL AMOUNTS/SEVERE POTENTIAL WITH THE ARRIVAL OF THE
NEXT SYSTEM SUNDAY NIGHT INTO MONDAY.

EARLY IN THE PERIOD...HAVE MAINTAINED DRY FORECAST FOR SATURDAY
NIGHT THROUGH SUNDAY AFTERNOON. MEDIUM RANGE MODELS HAVE CONTINUED
A GENERAL TREND OF SLOWING THE ARRIVAL OF THE NEXT FRONTAL
BOUNDARY AND UPPER LEVEL TROUGH. HAVE REDUCED AND TRIMMED POPS
BACK TO THE NORTHWEST FOR SUNDAY EVENING...AND ADDITIONAL
ADJUSTMENTS MAY BE NEEDED OVER THE NEXT COUPLE OF DAYS. THE MAIN
WINDOW OF SHOWERS/STORMS IS NOW EXPECTED LATE SUNDAY NIGHT INTO
MONDAY MORNING. THE LATER TIMING MEANS FAVORABLE SEVERE WEATHER
PARAMETERS WILL LIKELY STAY WEST OF THE FORECAST AREA...WITH THE
MOST LIKELY SCENARIO BEING A DECAYING MCS AND POSSIBLY SOME
LOCALLY HEAVY RAIN. STORMS MAY CONTINUE INTO THE AFTERNOON...AND
POSSIBLY MONDAY NIGHT DEPENDING ON HOW FAR SOUTH THE FRONT PUSHES.

LOOKING AHEAD...CONFIDENCE IN FORECAST DETAILS IS LOWER AS THE
OPERATIONAL GFS AND EURO VACILLATE BETWEEN WEAK TROUGHING AND
ZONAL FLOW ACROSS THE REGION. TIMING AND LOCATION OF THE VARIOUS
WEAK IMPULSES IS CHALLENGING AND RIGHT NOW THERE IS NO REASON TO
VARY FROM THE CONSENSUS BLEND POPS...ESSENTIALLY SLIGHT TO LOW
CHANCE IN EVERY PERIOD THROUGH FRIDAY. TEMPERATURES ARE EXPECTED
TO BE NEAR TO SLIGHT ABOVE NORMAL THROUGH THE PERIOD...WITH
AFTERNOON HIGHS GENERALLY IN THE 8OS AND LOWS IN THE 60S TO LOWER 70S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1244 PM CDT FRI AUG 29 2014

A LARGE AREA OF STORMS WILL SWEEP NORTHEAST THROUGH EASTERN IOWA AND
NORTHWEST ILLINOIS BETWEEN 21Z AND 04Z THIS AFTERNOON AND TONIGHT.
THIS WILL BRING A PERIOD OF IFR/MVFR HEAVY RAIN IN THUNDERSTORMS
WITH MVFR CIGS LIKELY AS WELL. WINDS WILL BE SOUTHERLY TODAY AROUND
12KTS...BECOME WEST TOWARD MORNING. SCATTERED TO ISOLATED SHOWERS
AND STORMS REMAIN A THREAT UNTIL SATURDAY MORNING AROUND 15Z...BUT
COVERAGE. AFTER STORMS MOVE OUT OF THE AREA OVERNIGHT...A MOIST AIR
MASS IN PLACE IS LIKELY TO PRODUCE MVFR CIGS AND VISIBILITY THROUGH
LATE SATURDAY MORNING.
ERVIN

&&

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

$$

SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...ERVIN
AVIATION...RP KINNEY





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