Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 281935
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
235 PM CDT THU AUG 28 2014

.SYNOPSIS...
ISSUED AT 209 PM CDT THU AUG 28 2014

THE LARGE AREA OF RAIN AND STORMS OVER CENTRAL AND WESTERN
IOWA...GENERALLY WEAKENED THIS MORNING AS THE MCV MOVED NORTH OF THE
MAIN MOISTURE TRANSPORT. IN ITS WAKE...THE TRAILING EDGE HAS BECOME
THE FOCUS FOR STORMS...NOW IN SOUTHEAST IOWA INTO MISSOURI. WE ARE
SEEING HEAVY RAIN AMOUNTS FROM THIS LINE.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 209 PM CDT THU AUG 28 2014

CONVECTION SHOULD CONTINUE TO SPREAD EAST AND NORTHEAST THIS
AFTERNOON...WHILE THE UPPER FLOW FOCUSES WEST AGAIN FOR LATE NIGHT
STORMS. THIS SHOULD ALLOW OUR EVENT THAT IS ONGOING TO END BY EARLY
EVENING IN THE EAST 1/2...WHILE NEW STORMS FIRE WELL TO THE WEST.
THERE IS SOME CHANCE FOR STORMS TO CONTINUE TO SPORADICALLY FIRE UP
ON THIS OUTFLOW TONIGHT...SO WE WILL NOT GO DRY...BUT RATHER
ISOLATED LATER THIS EVENING AND OVERNIGHT.

FRIDAY WILL SEE MANY DRY HOURS...BEFORE AN ACTIVE FRONT APPROACHES
FROM THE WEST. THIS FRONT MAY BE DELAYED INTO FRIDAY
NIGHT...RESULTING IN A DRY DAY FOR OUR CWA. EITHER WAY...A LOW POP
IS INCLUDED TO COVER A CHAOTIC FLOW AHEAD OF THE FRONT WITH AMPLE
MOISTURE. THE LARGE SYNOPTIC WAVE DRIVING THE FRONTAL RAINS SHOULD
MAINLY IMPACT THE REGION FRIDAY NIGHT.

TEMPERATURES SHOULD BE MODERATED BY CLOUDS OVERNIGHT...WITH LOWS IN
THE UPPER 60S TO LOWER 70S...WHILE FRIDAYS HIGHS AHEAD OF THE FRONT
SHOULD REACH THE LOWER TO MID 80S. CERTAINLY A WARM AND HUMID DAY.
ERVIN

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 209 PM CDT THU AUG 28 2014

THE MAIN FORECAST CONCERNS IN THE LONG TERM PERIOD ARE POTENTIAL FOR
ADDITIONAL ROUNDS OF HEAVY RAIN AND/OR SEVERE STORMS FRIDAY NIGHT
AND AGAIN SUNDAY NIGHT INTO MONDAY.

THE LATEST SUITE OF MEDIUM RANGE MODEL GUIDANCE SUPPORTS
WIDESPREAD CONVECTION FRIDAY NIGHT...SPREADING FROM WEST TO EAST
ACROSS THE FORECAST AREA. SUPPORT WILL COME FROM A RATHER SHARP
MID-LEVEL TROUGH AND SIGNIFICANT MOISTURE TRANSPORT AHEAD OF THE
BOUNDARY...PUSHING PRECIPITABLE WATER VALUES CLOSE TO 2 INCHES.
HAVE BOOSTED POPS ANOTHER NOTCH...INTO THE CATEGORICAL RANGE
ACROSS THE NORTHWEST. RELATIVELY MEAGER DEEP LAYER SHEAR SHOULD
KEEP THE OVERALL SEVERE RISK LOW...BUT WOULD NOT BE SURPRISED IF
WE END UP ISSUING A WARNING OR TWO...MAINLY FRIDAY EVENING.

SHOWERS SHOULD BE ENDING SATURDAY MORNING ACROSS THE
EAST...FOLLOWED BY A MAINLY DRY PERIOD SATURDAY AFTERNOON THROUGH
SUNDAY AFTERNOON. THE NEXT SIGNIFICANT UPPER WAVE IS FORECAST TO
ARRIVE SUNDAY NIGHT. PLENTIFUL MOISTURE AND MORE FAVORABLE DEEP
LAYER SHEAR SHOULD MEAN A MORE ROBUST THREAT FOR SEVERE
STORMS...IN ADDITION TO LOCALLY HEAVY RAIN. THIS WAVE IS EXPECTED
TO EXIT THE REGION DURING THE DAY ON MONDAY.

LOOKING AHEAD...THE OPERATIONAL GFS KEEPS MORE BROAD TROUGHING
ACROSS THE REGION...WHILE THE ECMWF SUGGESTS MORE OF A ZONAL FLOW
WITH ENERGY REMAINING NORTH AND SOUTH OF THE FORECAST AREA.
LOW POPS FROM THE CONSENSUS BLEND ARE REASONABLE AT THIS POINT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1210 PM CDT THU AUG 28 2014

A BROAD AREA OF LIGHT TO MODERATE RAIN...WITH VERY INFREQUENT
LIGHTNING EMBEDDED IS MOVING NORTHEAST THROUGH EASTERN IOWA TODAY.
THIS SHOULD PRODUCE RAIN AND MVFR CIGS AT CID...MLI...AND DBQ
THROUGH LATE AFTERNOON. VISIBILITIES WILL REMAIN NEAR 6 MILES MOST
OF THE DAY...BUT MAY DROP AS LOW AS 3 MILES IN MODERATE RAIN AT
TIMES. OTHERWISE...EAST TO SOUTHEAST WINDS UNDER 12 KTS WILL BE
FOUND THROUGH TONIGHT...AS CONDITIONS ARE MOST CONFIDENTLY
DRY...BUT SOME SHOWERS ARE POSSIBLE. OVERNIGHT LIGHT FOG IS
NEEDING TO BE WATCHED FOR WIDESPREAD 3 TO 5 MILE VISIBILITIES AS
MOIST WARM AIR ARRIVES FROM THE SOUTH TONIGHT. FRIDAY...SOME
ISOLATED SHOWERS OR STORMS ARE POSSIBLE AGAIN...WITH LOW COVERAGE
EXPECTED THROUGH NOON.
ERVIN

&&

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

$$

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





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