Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 012028
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
328 PM CDT TUE SEP 1 2015

.SYNOPSIS...
ISSUED AT 315 PM CDT TUE SEP 1 2015

12Z UA ANALYSIS HAS AN UPPER LEVEL HIGH OVER THE OHIO VALLEY AND AN
INFERRED WEAK UPPER LOW OVER WESTERN NEBRASKA. SATELLITE TRENDS
THROUGH MID AFTERNOON SHOW VERY LITTLE IN THE WAY OF DIURNAL CLOUD
DEVELOPMENT ACROSS EASTERN IOWA BUT SLIGHTLY MORE ACROSS ILLINOIS.

18Z SFC DATA HAS HIGH PRESSURE OVER THE OHIO AND TENNESSEE VALLEYS
AND A WEAK LOW OVER WESTERN SOUTH DAKOTA. DEW POINTS WERE IN THE 60S
AND 70S ACROSS THE MIDWEST WITH 50S ACROSS PARTS OF THE PLAINS.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 315 PM CDT TUE SEP 1 2015

VERY WARM AND HUMID CONDITIONS WILL CONTINUE THROUGH SUNSET WITH
HEAT INDEX READINGS IN THE LOW TO MID 90S.

QUIET BUT MUGGY CONDITIONS WILL BE SEEN TONIGHT AS A WEAK UPPER
LEVEL DISTURBANCE APPROACHES FROM THE PLAINS. THE FORCING IS BETTER
ACROSS THE WESTERN HALF OF IOWA SO SOME NOCTURNAL CONVECTION IS
EXPECTED TO DEVELOP THERE.

ON WEDNESDAY...ANY CONVECTION THAT DEVELOPS IN WESTERN IOWA WOULD BE
IN CENTRAL IOWA AT SUNRISE. THE FORCING WEAKENS DURING THE MORNING
SO THE CONVECTION SHOULD DECAY AS IT MOVES TOWARD THE AREA. ALTHOUGH
REMOTE...SOME ISOLATED SPRINKLES OR A STRAY SHOWER MIGHT MOVE INTO
THE EXTREME NORTHWEST PARTS OF BUCHANAN AND BENTON COUNTIES AROUND
MID DAY.

DURING THE AFTERNOON...AN UPPER LEVEL DISTURBANCE WILL MOVE FROM
MINNESOTA INTO WISCONSIN. ALTHOUGH THE BETTER FORCING IS NORTH OF
THE AREA...SOME ISOLATED DIURNAL CONVECTION MAY BE POSSIBLE IN THE
HIGHWAY 20 CORRIDOR FROM DUBUQUE ON WEST.

THE VERY WARM AND HUMID CONDITIONS WILL AGAIN CONTINUE ON WEDNESDAY
WITH MAX TEMPERATURES IN THE UPPER 80S TO LOWER 90S. HEAT INDEX
VALUES SHOULD AGAIN BE IN THE LOW TO MID 90S.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 315 PM CDT TUE SEP 1 2015

HAVE SOME SMALL POPS WED NGT NORTH (WHICH COULD NEED TO BE EXPANDED
INTO A FEW WESTERN COUNTIES) BEING IN CLOSE PROXIMITY TO THE
UPPER LEVEL DISTURBANCE PASSING FROM MN INTO WI... AND WITH WING OF
LOW TO MID LEVEL THETA-E ADVECTION ON VEERING JET. AFTER THIS
DISTURBANCE PASSES WILL SEE A RE-AMPLIFICATION OF UPPER LEVEL RIDGE
THROUGH THE CENTRAL CONUS AS UPPER LEVEL ENERGY DIGS INTO THE WEST.
THIS WILL PERSIST INTO THE UPCOMING HOLIDAY WEEKEND AND RESULT IN
CONTINUATION OF STAGNANT SUMMER PATTERN WITH VERY WARM/HOT AND
DRY CONDITIONS. HIGHS WILL BE IN THE UPPER 80S AND LOWER 90S... WITH
AFTN HEAT INDEX VALUES MID TO SOME UPPER 90S. MEANWHILE MUGGY NIGHTTIME
LOWS ONLY IN THE MID 60S TO LOWER 70S.

PATTERN SHIFT TO COOLER TEMPS STILL BEING SUGGESTED AROUND THE LABOR
DAY HOLIDAY AND JUST BEYOND...AS THE WESTERN TROUGH EJECTS ACROSS
THE NORTHERN CONUS. ATTENDANT SEASONABLY STRONG COLD FRONT SHOULD TEAM
UP WITH MONSOONAL MOISTURE FOR DECENT CHANCE OF FAIRLY WIDESPREAD
WETTING RAINS LATE SUN THROUGH MON NGT. FOR NOW HAVE KEPT POPS IN
LOWER CHANCE CATEGORY DUE TO TIMING UNCERTAINTIES WITH FRONT... BUT
ANTICIPATE IF TRENDS PERSIST THAT POPS WILL EVENTUALLY NEED CONSIDERABLE
RAISING WHEN TIMING CAN BE PINNED DOWN. IN WAKE OF FRONT WILL SEE
TEMPS COOLING TO NEAR NORMAL OR POSSIBLY A BIT BELOW AS DPROG/DT OF
GFS AND ECM SHOW COOLING TREND WITH 850 MB TEMPS DOWN THROUGH THE TEENS
TO POSSIBLY AROUND 10C.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1223 PM CDT TUE SEP 1 2015

VFR CONDITIONS WILL BE SEEN THROUGH 06Z/02 AS AN UPPER LEVEL HIGH
REMAINS ACROSS THE MIDWEST. DENSITY ALTITUDES MAY APPROACH 3000
THROUGH 00Z/02. AFT 06Z/02 MVFR CONDITIONS ARE EXPECTED TO DEVELOP
DUE TO LIGHT WINDS AND HIGH MOISTURE LEVELS IN THE LOWER
ATMOSPHERE. IT IS POSSIBLE THAT SOME PATCHY IFR CONDITIONS MAY
DEVELOP THROUGH 12Z/02. AFT 12Z/02 CONDITIONS WILL IMPROVE TO VFR.

&&

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

$$

SYNOPSIS...08
SHORT TERM...08
LONG TERM...05
AVIATION...08



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