Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 261735
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1235 PM CDT FRI SEP 26 2014

.SYNOPSIS...
ISSUED AT 332 AM CDT FRI SEP 26 2014

LATEST SFC ANALYSIS WAS INDICATING A LARGE RIDGE COMPLEX MAINTAINING
ACRS THE GRT LKS TO UPPER MS RVR VALLEY...WITH A FEW TROFS EMBEDDED
IN SOUTHERLY RETURN FLOW GRADIENT ACRS THE PLAINS. ALOFT...THE MAIN
FEATURE OF INTEREST CONTINUES TO BE ROGUE UPPER LOW/MULTI-CENTERED
VORT SEEN ON WATER VAPOR LOOP FROM ACRS NORTHEASTERN KS...TO WEST
CENTRAL IL STARTING TO HALT IT/S SOUTHERLY GYRATION. IMPRESSIVE
BLOCKING OMEGA UPPER RIDGE CONTINUES TO REIGN ACRS MUCH OF THE
SOUTHWESTERN CONUS...UP TO JUST SOUTHWEST OF THE HUDSON BAY REGION
OF CANADA.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 332 AM CDT FRI SEP 26 2014

TODAY...BULK OF SHORT RANGE MODELS SUGGEST THE UPPER LOW TO GYRATE
IN PLACE OR SLOWLY DRIFT ACRS THE IA/MO BORDER REGION BACK ACRS
WESTERN IA THROUGH THIS EVENING. THE SAME FCST CHALLENGE WILL
CONTINUE OF HOW MUCH MID DECK OF CLOUDS AND POSSIBLE LIGHT
SHOWERS/SPRINKLES THIS FEATURE WILL FORM AND MOVE ACRS THE LOCAL
FCST AREA. EASTERN FLANK OF THIS UPPER SYSTEM SHOULD CONTINUE TO
PRODUCE PATCHES OF MID DECK...AND A DIURNAL FLARE UP OF LIGHT
SHOWERS UP OUT OF NORTHERN MO AND INTO CENTRAL PORTIONS OF IA AS THE
DAY PROGRESSES. WILL KEEP THE FCST DRY FOR NOW WITH SILENT 14 POPS
ACRS THE WESTERN THIRD BANKING ON BULK OF ANY MEASURABLE PRECIP
REMAINING OFF TO THE WEST OF THE CWA LIKE THE 00Z RUN ECMWF
SUGGESTS. BUT ALSO COULD SEE THE NEED OF SOME POPS FOR ISOLATED TO
SCTRD PATCHES OF SHOWERS IN THESE AREAS FROM LATE MORNING AND
INTO THE HEATING OF THE AFTERNOON. SOUTHEASTERLY RETURN FLOW IN THE
BOUNDARY LAYER...SOME SUNSHINE MIXED WITH THE CLOUDS...AND PARCEL
MIXING UP CLOSE TO H85 MB SUPPORT ONGOING HIGHS FOR TODAY AND WILL
MAKE LITTLE OR NO CHANGES. BUT A CHANCE FOR SOME TEMPS IN THE WEST
TO BE TOO WARM IF CLOUDS AND PATCHES OF PRECIP MATERIALIZE AND HOLD
ON FOR MOST OF THE DAY.

TONIGHT...INTERESTING BROAD REX TYPE BLOCK FCST TO FORM ACRS THE MID
CONUS THROUGH TONIGHT...EFFECTIVELY TRAPPING UPPER LOW FEATURE ACRS
WESTERN HALF OF IA AND THE MO RVR VALLEY. SOME LINGERING MID DECK
CLOUDS POSSIBLE ACRS THE WESTERN CWA OFF THIS FEATURE FOR AWHILE
THIS EVENING...BUT EXPECT A CLEARING TREND OVERNIGHT. WITH THIS IN
MIND...AGAIN ONGOING LOW TEMPS LOOK ON TRACK AND WILL MAKE LITTLE
CHANGE...GENERALLY MID TO UPPER 50S. RIVER VALLEY AND LOW LYING AREA
FOG POSSIBLE TOWARD SUNRISE SAT MORNING IN AREAS WITH CLEAR SKIES.

.LONG TERM...(SATURDAY THROUGH NEXT THURSDAY)
ISSUED AT 332 AM CDT FRI SEP 26 2014

PERSISTENCE WILL BE THE RULE THROUGH THE WEEKEND WITH ONLY MINOR
CHANGES INTO EARLY NEXT WEEK AS BLOCKING PATTERN REMAINS IN PLACE.
THE SLOWLY MEANDERING UPPER LOW EMBEDDED IN THE BROADER UPPER RIDGE
AND WEAK SURFACE FLOW ON THE WESTERN PERIPHERY OF SURFACE HIGH OVER
THE EASTERN GREAT LAKES WILL REMAIN THE PRIMARY WEATHER FEATURES
THROUGH SUNDAY. THE RESULT WILL BE CONTINUED LIGHT EAST TO SOUTHEAST
SURFACE WINDS...PERIODS OF MID LEVEL CLOUDS...AND HIGHS REACHING THE
UPPER 70S TO AROUND 80 WITH OVERNIGHT LOWS MAINLY IN THE 50S.

THE MAIN QUESTION BEYOND WILL BE THE TIMING OF THE PATTERN BREAKDOWN
AS THE UPPER RIDGE MOVES EAST AND WESTERN TROUGH ADVANCES. LATEST
MODELS CONTINUE TO CENTER THIS CHANGE AROUND WEDNESDAY...WITH THE
GFS A SLIGHTLY FASTER OUTLIER. ASSOCIATED WARM AIR ADVECTION AND
MOISTURE RETURN IN MODEL BLENDS SUGGESTS RAIN AND ISOLATED
THUNDERSTORM CHANCES ENTERING THE WEST AS EARLY AS TUESDAY NIGHT...
WHICH BASED ON EXPERIENCE MAY BE A BIT TOO FAST. RAIN AND AT LEAST
ISOLATED THUNDERSTORMS THEN CANNOT BE RULED OUT FROM WED THROUGH
THU NIGHT AS A FRONTAL SYSTEM SLOWLY ADVANCES THROUGH THE REGION
AND CHANCE POPS ARE MAINTAINED. ASSOCIATED CLOUD COVER WILL LIKELY
LIMIT HIGHS TO THE LOWER TO MID 70S OVER MOST OF THE AREA BY THU.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1229 PM CDT FRI SEP 26 2014

VFR CONDITIONS TO DOMINATE TAF CYCLE WITH S/SE WINDS 5-10 KTS...SCT
MID CLOUDS AND FEW-SCT PM CUMULUS. PATCHY FOG WITH MAINLY MVFR TO LOCAL
IFR VSBYS ANTICIPATED TOWARD DAYBREAK.

&&

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

$$

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




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