Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 220440
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1140 PM CDT SUN SEP 21 2014

.SYNOPSIS...
ISSUED AT 311 PM CDT SUN SEP 21 2014

AN EXTENSIVE DECK OF STRATOCU THAT MOVED SOUTH OUT OF MN AND WI THIS
MORNING ENCOMPASSED ALL BUT THE SOUTHERN THIRD OF THE FORECAST AREA
THIS AFTERNOON. THESE CLOUDS WERE ASSOCIATED WITH THE WRAP AROUND
CYCLONIC FLOW OF MOISTURE AND INSTABILITY IN THE WAKE OF THE
DEPARTING SURFACE AND UPPER LEVEL LOWS OVER THE EASTERN GREAT LAKES.
OVERALL...THE CLOUD FIELD WAS SLOWLY NARROWING AND THINNING OUT AS
THE SYSTEM SLIDES EAST AND TRANSITIONS TOWARD A MORE ANTICYCLONE
FLOW. CLOUD COVER AND COLD AIR ADVECTION HAS LIMITED HIGHS SO FAR TO
THE A RANGE FROM NEAR 60 NORTH TO AROUND 70 IN THE FAR SOUTH. NW
WINDS AHEAD OF HIGH PRESSURE OVER WESTERN NEB AND SD WAS PULLING IN
DEWPOINTS IN THE UPPER 40S TO LOWER 50S.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 311 PM CDT SUN SEP 21 2014

MAIN CHALLENGE CENTERS AROUND TEMPERATURES AS RIDGING ALOFT AND HIGH
PRESSURE AT THE SURFACE BUILD INTO THE AREA. CURRENT SATELLITE
TRENDS SUGGEST THE CLOUDS WILL CONTINUE TO NARROW TO AN AXIS FROM
ABOUT CEDAR RAPIDS TO PRINCETON IL BY LATE AFTERNOON. THIS SHOULD
THEN GIVE WAY TO CLEAR SKIES BY EARLY EVENING WITH ONLY A FEW
STRAY CLOUDS POSSIBLY WANDERING INTO THE FAR NW OVERNIGHT FROM AN
UPSTREAM CLOUD DECK OVER WESTERN MN. OTHERWISE...THE OVERNIGHT WILL
BE MOSTLY CLEAR WITH VERY LIGHT TO NORTHWEST WINDS BECOMING VARIABLE
TOWARD MORNING AS THE CENTER OF THE PLAINS HIGH ADVANCES TO SOUTH
CENTRAL IA. THESE NEARLY IDEAL CONDITIONS FOR RADIATIONAL COOLING
SHOULD LEAD TO LOWS CLOSE TO THOSE OBSERVED UPSTREAM IN THE NORTHERN
PLAINS...FROM AROUND 40 TO THE MID 40S OR AT THE LOW END OF MOS
GUIDANCE. WITH CROSSOVER TEMPERATURES FROM THIS AFTERNOON LIKELY IN
THE UPPER 40S TO AROUND 50...FOG IS A GOOD POSSIBILITY. FOR
NOW...WITH SOME UNCERTAINTY DUE TO THE CONTINUED ADVECTION OF COOLER
AND DRIER AIRMASS ALONG WITH THE LACK OF FOG UPSTREAM THIS
MORNING...WILL GO WITH PATCHY WORDING CONFINED TO EAST CENTRAL IA
AND NW IL WHERE THIS AFTERNOON/S CLOUD COVER IS LIKELY TO LINGER THE
LONGEST.

MONDAY...SURFACE AND UPPER LEVEL RIDGING WILL PROVIDE LIGHT WINDS
AND MOSTLY SUNNY SKIES. GUIDANCE TEMPERATURES IN THE UPPER 60S TO
AROUND 70 LOOK REASONABLE.

.LONG TERM...(MONDAY NIGHT THROUGH NEXT SUNDAY)
ISSUED AT 311 PM CDT SUN SEP 21 2014

MONDAY NIGHT THROUGH WEDNESDAY...MOST 12Z RUN MODELS IN GOOD AGREEMENT
OF SUGGESTING BOTH SFC AND UPPER RIDGING TO CONTINUE TO PRESS
EASTWARD ACRS THE MID/UPPER MS RVR VALLEY AND WESTERN GRT LKS MON
NIGH INTO TUE FOR CONTINUED FAIR WX PATTERN. MAINLY CLEAR SKIES
AND LIGHT WINDS BEFORE SOUTHEASTERLY SFC RETURN FLOW COMMENCES...
TO MAKE FOR A COOL NIGHT MON NIGHT WITH LOWS IN THE MID TO UPPER
40S. WILL NOT ADD IT TO THE GRIDS AT THIS POINT...BUT SOME RVR
VALLEY AND LOW LYING AREA FOG POSSIBLE AFTER 09Z TUE. SOME MID AND
HIGH LEVEL CLOUDS MAY SPILL IN FROM THE WEST ACRS THE WESTERN CWA
TUE AFTERNOON OFF NORTHERN PLAINS UPPER LOW...BUT THE DAY STILL TO
BE CHARACTERIZED BY MOSTLY SUNNY SKIES AND SOUTH TO SOUTHEAST SFC
BREEZE MIXING TEMPS INTO THE LOW TO MID 70S. THE UPSTREAM UPPER
WAVE STILL PROGGED TO HAVE TROUBLE MIGRATING EASTWARD BATTLING
STOUT RIDGE COMPLEX HOLDING FIRM ACRS MUCH OF THE EASTERN CONUS
THROUGH MID WEEK. AND WITH SUCH A DRY COLUMN IN PLACE ESPECIALLY
IN THE SUB-H6 MB LAYER...EXPECT ANY SHOWERS ASSOCIATED WITH THE
UPPER S/W TROF TO DRY UP AS THEY TRY TO ADVANCE EASTWARD OUT OF
CENTRAL IA. AT WORST MAYBE SOME HIGH BASED SPRINKLES AND MID
DECK/AC MAKING THEIR WAY INTO THE WEST LATE TUE NIGHT AND ON WED.
THIS NOT WORTH PUTTING ANY KIND OF MENTIONABLE PRECIP CHC/S IN THE
FCST EVEN INTO WED NIGHT AS THE UPPER LEVEL TROF DAMPENS ACRS MO
RVR VALLEY/WESTERN IA. DEPENDING ON HOW MUCH CLOUD COVER SPILLS IN
FROM THE WEST OFF THIS SYSTEM AND A SOUTHEASTERLY COMPONENT TO THE
SFC WIND AS OPPOSED TO MORE OF A SOUTH BREEZE...WED MAY BE A
DEGREE OR TWO COOLER THAN TUE IN SOME SPOTS. OTHERWISE A SIMILAR
DAY.

THURSDAY THROUGH NEXT SUNDAY...THE UPPER TROF CONTINUES TO DAMPEN
AND WASH OUT ACRS THE SOUTHEASTERN PLAINS AND UP ACRS IA THROUGH
THU...THEN LATEST RUN MEDIUM RANGE SOLUTIONS GENERALLY REESTABLISH
LARGE/BROAD UPPER RIDGE ACRS MUCH OF THE EASTERN 2/3S OF THE CONUS.
SEASONABLY STRONG GRT LKS SFC ANTICYCLONE EVEN PROGGED TO RETROGRADE
SOME WITH IT/S WESTERN FLANK MAINTAINING IT/S GRIP ON THE WESTERN GRT
LKS/UPPER MS RVR VALLEY. WITH A MODERATING THERMAL COLUMN/AIRMASS
ACRS THE REGION INTO THE LATE WEEK UNDER THIS REGIME AND RETURN
FLOW MOISTURE SOURCES CUT-OFF...THE FAIR WX PATTERN TO CONTINUE ALONG
WITH TEMPS AT OR ABOVE NORMAL INTO THE WEEKEND.    ..12..

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1137 PM CDT SUN SEP 21 2014

HIGH PRESSURE WILL CONTINUE BUILDING INTO THE AREA OVER THE NEXT 24
HOURS PROVIDING IDEAL FLYING CONDITIONS WITH MAINLY CLEAR SKIES...
LIGHT WINDS AND UNLIMITED VISIBILITY. THERE REMAINS A LOW CHANCE OF SOME
GROUND FOG DEVELOPING AROUND SUNRISE... BUT PROBABILITY APPEARS
TOO LOW FOR INCLUSION AT TAF SITES.

&&

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

$$

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






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