Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 021743
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1243 PM CDT TUE SEP 2 2014

.SYNOPSIS...
ISSUED AT 354 AM CDT TUE SEP 2 2014

SMALL CONVECTIVE CLUSTER OVER NORTH CENTRAL IA MOVING QUICKLY E/NE
AHEAD OF COMPACT SHORTWAVE ALONG MID LEVEL FRONTAL ZONE.
MEANWHILE... FAVORABLE RIGHT ENTRANCE REGION OF H3 JET INTERACTING
WITH SFC FRONT FOR ACTIVE CONVECTION AND HEAVY RAIN WITH TRAINING
EXTENDING FROM KS/OK BORDER TO INDIANA. DENSE CIRRUS BLOWOFF
BLANKETING SOUTHERN HALF OF CWA AIDING IN WARMER TEMPS RANGING FROM
MID 60S TO AROUND 70. NORTHERN HALF OF CWA MAINLY CLEAR WITH THIN
CIRRUS... AND PRESENCE OF SHALLOW STEEP INVERSION ALLOWING WINDS TO
GO NEAR CALM FOR IDEAL RADIATIONAL COOLING WITH TEMPS IN THE U50S TO
LOWER 60S AND ALSO PATCHY DENSE FOG... ESPECIALLY IN RIVER VALLEYS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 354 AM CDT TUE SEP 2 2014

WILL SEE SOUTHERN PORTION OF CONVECTIVE CLUSTER PROPAGATE/DEVELOP
INTO NORTHERN CWA THIS AM... MAINLY NORTH OF HWY 30 AHEAD OF COMPACT
UPPER LEVEL SHORTWAVE. CAN/T RULE OUT SOME GUSTY WINDS 20-30 KTS
WITH DCAPE APPROACHING 1000 J/KG OVER NORTHEAST IA... AND ALSO SMALL
HAIL POSSIBLE WITH CAPES AROUND 500 J/KG IN -10C TO -30C LAYER.
OUTSIDE OF CONVECTION...WILL SEE PATCHY DENSE FOG DOWN THROUGH HWY 34
BURNING OFF BY 14Z WITH MOCLDY TO START NORTH AND SOUTH... THEN ALL
AREAS BECOMING MOSUNNY THIS AFTN. BUFR SOUNDINGS SUPPORT MIXING TO
JUST BELOW 850 MB WHICH YIELDS HIGHS FAIRLY SIMILAR TO THOSE OF YSTDY
AND MOSTLY IN THE RANGE OF THE UPPER 70S TO LOWER 80S. MIXING MAY ALSO
LOWER DEWPTS IN SOME AREAS INTO THE 50S... BUT OTHERWISE AROUND 60 TO
L60S FOR DEWPTS COMBINED WITH TEMPS IN U70S/L80S MAKING FOR ANOTHER REAL
NICE DAY.

TONIGHT... HIGH PRESSURE RIDGE TO TRAVERSE CWA. FAVORED NEAR THE COOL
SIDE OF GUIDANCE MANY AREAS GIVEN COMBINATION OF MAINLY CLEAR SKIES
MOST OF TONIGHT... AND LIGHT TO CALM WIND WITH SHALLOW STEEP INVERSION.
WITH 850 TEMPS AROUND 14-15C WOULDN/T BE SURPRISED TO SEE A FEW DRAINAGE
SITES SEE LOWS IN THE MID 50S NORTHERN CWA... OTHERWISE LOWS MAINLY IN
THE UPPER 50S TO LOWER 60S. MAY SEE CLOUDS DEVELOP/INCREASE LATE WITH
INCREASING MID LEVEL WARM ADVECTION AS RIDGE AXIS BEGINS TO SHIFT EAST.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 354 AM CDT TUE SEP 2 2014

WEDNESDAY THROUGH FRIDAY...00Z RUN MODELS GENERALLY SUGGEST LLVL
WARM FRONT WILL TRY TO RETREAT NORTHWARD ACRS AT LEAST THE SOUTHERN
CWA AS WED PROGRESSES. THE MODELS DO VARY ON NORTHWARD PROGRESSION
WITH THE 00Z ECMWF ALMOST NORTH OF THE CWA BY WED EVENING...BUT THAT
MODEL BREAKS OUT VARY LITTLE WAA TYPE PRECIP...WHILE THE 00Z GFS AND
NAM DEVELOP SCTRD ELEVATED SHOWERS AND THUNDERSTORMS ACRS MUCH OF
THE CWA DELAYING WARM FRONT PROGRESSION. EXTENT OF PRECIP AND CLOUD
COVER ALSO TO BE A TEMP LIMITING FACTOR EVEN IN ORGANIZING WARMING
PROFILES. COULD BE LARGE TEMPERATURES FROM NORTH OF THE BOUNDARY
HELD IN THE 70S...WHILE AREAS TO THE SOUTH OF THE FRONT MAY PUSH THE
UPPER 80S IF ENOUGH SUNSHINE CAN OCCUR. THE NAM AND GFS FCST
SOUNDINGS HAVE HIGH LLVL SHEAR PROFILES WED AFTERNOON INTO EARLY
EVENING IN VCNTY OF THE BOUNDARY...POTENTIAL TROUBLE IF A STORM
COULD SOME HOW GET SFC ROOTED. THE 00Z ECMWF ROLLS A STRONG ELEVATED
MCS ACRS MN INTO WI...POSSIBLY CLIPPING THE FAR NORTHERN CWA LATER
WED NIGHT WITH THE REST OF THE CWA IN THE WARM SECTOR OF MEAN RIDGE
AXIS AND TEMPS NOT DIPPING OUT OF THE 70S. FORCING PROFILES OF THE
NAM AND GFS AS WELL AS PLACEMENT SUGGEST A WING SCTRD ELEVATED WAA
SHOWERS/STORMS TO CONTINUE ACRS THE CWA WED NIGHT WITH A FEW STORMS
POSSIBLY BECOMING ACTIVE HAILERS. WITH UNCERTAINTY WILL KEEP LOW TO
MODERATE CHC POPS GOING FOR WED INTO WED NIGHT BEFORE CONVECTIVE WAA
WING MOVES OFF TO THE EAST AND NORTHEAST FOR THU. AHEAD OF DIGGING
UPPER LEVEL TROF ACRS NORTHERN PLAINS AND LLVL FRONTAL SYSTEM...GOOD
MODEL AGREEMENT OF SUGGESTING THE ENTIRE CWA TO BE IN PRE-FRONTAL
WARM SECTOR ON THU. A BREEZY HOT DAY FOR THIS TIME OF YEAR WITH
WIDESPREAD UPPER 80S TO LOWER 90S. SOME MID 90S MAY EVEN BE
POSSIBLE. EVEN TAKING INTO ACCOUNT DRY DOWN MIXING OF SFC DPTS INTO
THE UPPER 60S OR EVEN MID 60S...HEAT INDEX READING TO RANGE FROM 95
TO OVER A 100 THU AFTERNOON. IF SFC DPTS CAN MAINTAIN OR ADVECT UP
INTO THE 70-75 DEGREE RANGE LIKE THE MODELS SUGGEST...A POSSIBLE
HEAT ADVISORY WILL BE NEEDED FOR PORTIONS OF THE LOCAL FCST AREA.
SOUTHWEST SFC WINDS OF 15 TO 20+ MPH AND HIGHER GUSTS BY THU
AFTERNOON. MAIN LLVL BOUNDARY PUSH FROM THE NORTHWEST STILL LOOKS TO
BE LATER THU NIGHT INTO FRI MORNING...WITH PRE-FRONTAL CAPPING
INVERSION LIMITING ANY CONVECTIVE DEVELOPMENT TO OCCURRING ALONG AND
POST-FRONTALLY ELEVATED IN NATURE. STRONGER FORCING IN THE VCNTY OF
THE MAIN WAVE PASSING ACRS THE UPPER MIDWEST TO OCCUR ACRS MN AND WI
THU NIGHT INTO FRI...WHILE BETTER LLVL THTA-E FEED/CONVERGENCE AND
THERMODYNAMICS ALONG THE BOUNDARY OCCUR ACRS THE SOUTHERN PLAINS
INTO MO. ONCE AGAIN MOST OF THE CWA COULD BE IN BETWEEN THE TWO MAIN
CONVECTIVELY ACTIVE REGIONS. BUT TOO CLOSE TO DISCERN FOR NOW AND
WILL KEEP MODERATE POPS GOING THU NIGHT INTO FRI. POST-FRONTAL COOL
DOWN ALONG WITH POSSIBLE PRECIP OUTFLOW COOLING TO KNOCK DOWN FRI
HIGHS BACK INTO THE 70S FOR MOST OF THE CWA EXCEPT FAR SOUTHEAST.
L/W UPPER TROFFINESS TO ESTABLISH ACRS THE GRT LKS FRI NIGHT INTO
SAT...WITH LLVL RIDGE COMPLEX ENGULFING THE UPPER MIDWEST. SOME
SIGNS OF POST FRONTAL OVERRUNNING SHOWERS SKIRTING ACRS THE SOUTHERN
CWA FRI NIGHT INTO EARLY SAT MORNING...BUT HOW FAR NORTH THIS
ACTIVITY MAKES IT STILL AT QUESTION. MORE PROGRESSIVE RIDGE
IN-BUILDING WOULD MAKE FOR A DRY FRI NIGHT EVEN IN THE SOUTH LIKE
THE LATEST GFS IS TRENDING TOWARD.

SATURDAY THROUGH NEXT MONDAY...LATEST 00Z RUN MEDIUM RANGE GUIDANCE
AND ENSEMBLES STILL SUGGESTING A NICE WEEKEND CHARACTERIZED BY HIGH
PRESSURE COMPLEX ACRS THE GRT LKS...COOLED THERMAL PROFILES
SUPPORTING HIGHS IN THE 70S AND LOWS IN THE 50S AND EVEN SOME 40S
ESPECIALLY SAT NIGHT. LONGER RANGE INDICATIONS SUGGEST GULF OF AK
WAVE AND UPPER JET ENERGY TO DIG DOWN ACRS WESTERN CANADA AND INTO
THE NORTHERN ROCKIES EARLY NEXT WEEK...MAKING FOR A SIMILAR SET UP
TO WHAT WILL OCCUR AT THE END OF THIS CURRENT WEEK. SOUTH-WESTERLIES
RELOAD ACRS THE PLAINS BY LATE MON...WITH LLVL RETURN FLOW AND
ASSOCIATED WARM FRONT ORGANIZING SOMEWHERE ACRS THE CENTRAL PLAINS
AND MID MS RVR VALLEY. WHILE MON MAY BE MAINLY DRY AND THERMALLY
MODERATING...MON NIGHT INTO NEXT TUE MAY BECOME MORE ACTIVE WITH A
POSSIBLE WARM AIR ADVECTION MCS OR CONVECTIVE GENERATION SCENARIO
UNFOLDING AGAIN ACRS THE UPPER MIDWEST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1240 PM CDT TUE SEP 2 2014

VFR TO MOSTLY VFR CONDITIONS WITH FAIR SKIES EXPECTED THROUGH AT LEAST
03/18Z. WEAK SURFACE RIDGING WILL ALLOW FOR LIGHT WEST WINDS TO BECOME
VARIABLE TONIGHT WITH PATCHY MVFR FOG POSSIBLE TOWARD SUNRISE. WINDS
WILL SHIFT TO THE SOUTH AT 5 TO 10 KTS WEDNESDAY MORNING UNDER CONTINUING
FAIR SKIES AS HIGH PRESSURE MOVES EAST.

&&

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

&&

$$

SYNOPSIS...05
SHORT TERM...05
LONG TERM...12
AVIATION...NICHOLS





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