Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 222329
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
629 PM CDT MON SEP 22 2014

.SYNOPSIS...
ISSUED AT 318 PM CDT MON SEP 22 2014

HIGH PRESSURE CENTERED OVER IA...MO AND IL WAS PROVIDING CLEAR SKIES
AND LIGHT WINDS OVER THE AREA THIS AFTERNOON. DESPITE THE SUNSHINE...
TEMPERATURES HAVE WARMED ONLY INTO THE UPPER 60S TO LOWER 70S DUE
TO THE WEAK MIXING. THE AIRMASS CONTINUES TO MODIFY AND DRY...AS
EVIDENT BY DEWPOINTS RUNNING AS MUCH AS 5 TO 10 DEGREES LOWER THAN
YESTERDAY AT THIS TIME. ALOFT...THE AREA WAS UNDER SUBSIDENT NW
FLOW BETWEEN A TOUGH AXIS JUST WEST OF THE APPALACHIANS AND A
RIDGE AXIS OVER THE PLAINS. A STRONG UPPER VORTEX MOVING THROUGH
WY WAS PUSHING THROUGH THE MEAN RIDGE AXIS...SPEWING AN ARCH OF
DISSIPATING HIGH CLOUDS AS FAR NW AS EASTERN SD INTO WESTERN IA.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 318 PM CDT MON SEP 22 2014

TEMPERATURES AND POTENTIAL FOR SHALLOW EARLY MORNING FOG ARE THE
PRIMARY CONCERNS. HIGH PRESSURE...CENTERED OVER NE MO...IS PROGGED
TO SHIFT EAST TO THE OHIO VALLEY REGION BY 12Z...LEADING TO A WEAK
PRESSURE GRADIENT AND SOUTHERLY FLOW OVER ESPECIALLY NE MO INTO
EASTERN IA. IN THE UPPER LEVELS...THE PLAINS RIDGE AXIS WILL NUDGE
EAST AS THE WY LOW LIFTS NE INTO THE NORTHERN PLAINS TUESDAY. THE
BIG QUESTION WILL BE HOW FAR AND TO WHAT DEGREE THE HIGH LEVEL
CLOUDS REACH INTO THE FORECAST AREA TO LIMIT RADIATIONAL COOLING
LATE TONIGHT. AT THIS TIME...CONCEPTUAL MODELS ALONG WITH MOISTURE
AND WARM ADVECTION TOOLS SUGGEST THIS WILL BE MINIMAL AND IMPACT
PRIMARILY THE SW THIRD OF THE FORECAST AREA LATE. THIS WOULD SET THE
STAGE FOR ANOTHER NIGHT OF COMPLETE DECOUPLING WITH PERHAPS LIGHT
SOUTHERLY WINDS TOWARD MORNING IN THE WEST. WITH A SIMILAR AIRMASS
IN PLACE AS LAST NIGHT...EXCEPT DRIER AT THE SURFACE AND PERHAPS A
BIT WARMER ABOVE THE BOUNDARY LAYER...WILL AGAIN UNDERCUT GUIDANCE
THAT WAS TOO WARM WITH MINS LAST NIGHT...ESPECIALLY IN THE NORTH AND
EAST WITH A RANGE FROM AROUND 40 TO 48 FROM NE TO SW. WOULD NOT BE
SURPRISED TO SEE A FEW VALLEY SITES AGAIN DIP INTO THE UPPER 30S.

WITH THE LOWER DEWPOINTS AND FULL SUNSHINE TODAY TO FURTHER DRY
SOILS AND VEGETATION...THE POTENTIAL FOR FOG LOOKS LOWER THAN THIS
MORNING. HOWEVER...CONDITIONS WILL LIKELY SUPPORT FOG ALONG THE MS
RIVER AND HAVE INCLUDED MENTION FROM THE QUAD CITIES NORTHWARD.

TUESDAY...OUTSIDE OF SOME CI FROM THE PLAINS SYSTEM...WILL LIKELY
HAVE ANOTHER DAY SIMILAR TO TODAY...EXCEPT A FEW DEGREES WARMER.
LIGHT SOUTHERLY WINDS TAP INTO A WEAK WARM ADVECTION REGIME AND
GUIDANCE HIGHS AROUND 70 INTO THE LOWER 70S LOOKS REASONABLE.

.LONG TERM...(TUESDAY NIGHT THROUGH NEXT MONDAY)
ISSUED AT 318 PM CDT MON SEP 22 2014

TUESDAY NIGHT THROUGH FRIDAY...UPSTREAM UPPER LOW CURRENTLY OVER THE
NORTHERN ROCKIES/ID WILL LOOK TO RIDGE-RIDE TOWARD THE UPPER MS RVR
VALLEY THROUGH WED MORNING. BULK OF 12Z RUN MEDIUM RANGE SOLUTIONS
CONTINUE TO SUGGEST THIS FEATURE TO GET BLOCKED BETWEEN BROAD
BOOKEND UPPER HIGH PRESSURE REGIONS...AND DAMPEN/WASH OUT AS IT GETS
SQUEEZED INTO THE WESTERN GRT LKS THROUGH THU. THIS WAVE WILL LOOK TO
TRY AND TOP-DOWN SATURATE THE COLUMN AS IT PROPAGATES EASTWARD ACRS
THE REGION...BUT WITH SUCH A LIMITED MOISTURE SOURCE OR FIELD
GETTING DRAGGED ALONG WITH IT...PLUS SUCH DRY LOW TO MID LEVELS TO
OVERCOME...CAN SEE THIS FEATURE PRODUCING A FEW ROUNDS OF ONLY LIGHT
SHOWERS OR MORE LIKE SPRINKLES INTO THE WESTERN TO NORTHWESTERN
THIRD OF THE DVN CWA LATE TUE NIGHT AND INTO WED. THE MAIN UPPER
WAVE ASSOCIATED WITH THE TROF ALOFT WILL DRIFT EASTWARD ACRS THE CWA
WED NIGHT INTO THU MORNING...BUT AGAIN SEE MAINLY SOME MID AND HIGH
CLOUDS WITH THIS FEATURE AND AT MOST A FEW SPRINKLES HERE AND THERE
ESPECIALLY ALONG AND NORTH OF I80 WED NIGHT INTO THU AM. FEEL THESE
MINIMAL PRECIP CHANCES STILL NOT WORTH MENTIONING AT THIS POINT
AND WILL KEEP THE FCST DRY AND SEASONABLE THROUGH THU. SOME MID AND
HIGH CLOUDS OFF THE UPPER LOW MAY TEMPER WED HIGHS WEST OF THE MS
RVR SOME...ONGOING HIGH TEMPS ALREADY TAKING THIS INTO ACCOUNT AND
WILL MAKE LITTLE OR NO CHANGES. WILL ADVERTISE MORE WIDESPREAD MID
70S ON THU...BUT SOME CONCERN LINGERING CLOUD COVER FROM PASSING
WAVE ALOFT/ALTHOUGH WEAKENING/ MAY KEEP HIGHS SIMILAR TO WED. ON
FRI THE SOLUTIONS GENERALLY ADVERTISING A TYPE OF BROAD REX BLOCK
ACRS THE MID AND EASTERN CONUS. MORE SUNSHINE AND THERMALLY
MODERATING COLUMN WOULD SUGGEST HIGHS ABOVE NORMAL IN THE UPPER
70S ACRS MUCH OF THE CWA. A DRYING SFC LAYER ALL WEEK MAY ALLOW FOR
SOME 80 DEGREE READINGS AS WELL...BUT SOME OF THE SOLUTIONS/SUCH AS
THE NEW 12Z ECMWF/ ADVERTISE MORE OF A SOUTHEASTERLY COMPONENT TO
LLVL WINDS WHICH ARE NOT THE MOST WARMING OF FLOWS.

SATURDAY THROUGH NEXT MONDAY...LONGER RANGE INDICATIONS SUGGEST BLOCKING
RIDGE COMPLEX TO CONTINUE TO REIGN ACRS THE MID AND EASTERN CONUS...
WHILE UPSTREAM L/W TROF MIGRATES INLAND OFF THE EASTERN PACIFIC
AND ACRS THE WESTERN CONUS. WILL KEEP SAT AND SUNDAY DRY AND NEAR
OR ABOVE NORMAL UNDER SUCH A PATTERN AND CURRENTLY INDICATED
AIRMASS IN PLACE. EARLY NEXT WEEK MAY BECOME MORE INTERESTING WITH
THE WESTERN L/W TROF MAKING ITS WAY ACRS THE ROCKIES...WITH SOME
SIGNAL OF AN ENHANCED WAVE/LOW GETTING DRAWN UP OFF THE GULF TO
THE LEE OF THE TROF AND POSSIBLY MAKING IT/S WAY UP THE MS RVR AND
TOWARD THE CWA BY MON NIGHT OR TUE. THE 12Z ECMWF IS THE MOST
BULLISH IN HANDLING OF THIS SCENARIO...WHILE THE 12Z GFS ERODES
ANY ADVANCING WAVE INTO LINGERING RIDGE AXIS TO THE NORTH BEFORE
IT CAN MAKE IT UP TOWARD THE AREA. WILL KEEP THE FCST DRY THROUGH
DAY 7...BUT THE ADVANCING L/W TROF ITSELF WILL EVENTUALLY BRING
THE NEXT MAIN ORGANIZED CHC FOR PRECIP PROBABLY SOMETIME BY NEXT
MID WEEK.    ..12..

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 621 PM CDT MON SEP 22 2014

VFR CONDITIONS WILL PERSIST THROUGH THE TAF CYCLE AS HIGH PRESSURE
GRADUALLY SHIFTS INTO THE OHIO VALLEY. SOME FOG MAY ONCE AGAIN
DEVELOP TOWARD DAYBREAK BUT MAINLY IN RIVER VALLEYS AND NOT
ANTICIPATING IMPACTS TO TERMINALS ATTIM. LIGHT WINDS WILL PREVAIL
TONIGHT GRADUALLY BECOMING SOUTHERLY...WITH S/SE WINDS 6-12 KTS ON
TUESDAY.

&&

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

$$

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





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