Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 011148
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
648 AM CDT WED OCT 1 2014

.SYNOPSIS...
ISSUED AT 402 AM CDT WED OCT 1 2014

AREA RADARS SHOWED A LARGE MCS FROM NORTHEAST KS ACROSS NORTHEAST MO
INTO WESTERN IA ADVANCING NORTHEASTWARD. THIS WAS LINKED TO AN UPPER
LEVEL SHORTWAVE ROUNDING THE BASED OF A LARGER TROUGH ENCOMPASSING
THE ROCKIES AND PLAINS. 00Z UPPER AIR ANALYSIS SHOWED A SHARP...
WEAKENING RIDGE AXIS OVER IL AND WI. AT THE SURFACE THE LOCAL AREA
REMAINED IN A COOL LOW LEVEL SOUTHEAST FLOW OUT OF HIGH PRESSURE
OVER THE GREAT LAKES. A SURFACE WARM FRONT REACHED ROUGHLY FROM ST
JOSEPH MO E-SE ACROSS NORTHERN MO INTO SOUTHERN IL. SURFACE
DEWPOINTS WERE IN THE 60S SOUTH OF THIS AXIS...WHILE 40S AND A FEW
LOWER 50S WERE COMMON TO THE NORTH OVER EASTERN IA AND NW IL.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 402 AM CDT WED OCT 1 2014

MAIN FOCUS IS ON SHOWERS AND THUNDERSTORMS TODAY AND TONIGHT AS THE
BROAD UPPER TROUGH TO THE WEST GRADUALLY SHIFTS EASTWARD. THE LEAD
UPPER LEVEL SHORTWAVE AND CLUSTER OF OVERNIGHT SHOWERS AND
THUNDERSTORMS WILL GRADUALLY WORK INTO THE WEST THIS MORNING IN A
WEAKENING FASHION. AN UPSTREAM STRONGER WAVE EVIDENT ON WV IMAGERY
OVER NEB AND KS WILL LIKELY TRIGGER ADDITIONAL SHOWERS AND
THUNDERSTORMS LATE MORNING THROUGH THIS AFTERNOON AS IT ROTATES INTO
WESTERN IA. THE OVERALL SETUP WILL IS IN LINE WITH THE PREVIOUS
FORECAST...SUPPORTING GREATEST POPS MAINLY WEST OF THE MS RIVER WITH
AREAS TO THE EAST POSSIBLY NOT LIKELY SEEING ANY SHOWERS OR
THUNDERSTORMS UNTIL AFTERNOON...OR POSSIBLY THE EVENING OVER N
CENTRAL IL. AT THE SURFACE...THE WARM FRONT WILL ADVANCE NORTHEAST
THROUGH MOST OF THE FORECAST BY EVENING...ALLOWING THE MOIST...MILD
AIRMASS POISED JUST TO THE SOUTH TO OVERSPREAD THE FORECAST AREA.
THIS SHOULD PUSH TEMPERATURES INTO THE 70S OVER ALL BUT THE HIGHWAY
20 CORRIDOR.

TONIGHT...WIDESPREAD SHOWERS AND AT LEAST SCATTERED THUNDERSTORMS
ARE LIKELY AS ADDITIONAL IMPULSES ROTATE THROUGH THE CYCLONIC SW
FLOW ALOFT THAT WILL HAVE OVERSPREAD THE AREA. WHILE MOISTURE WILL
BE ABUNDANT IN THE OPEN FLOW FROM THE GULF...SHEAR AND INSTABILITY
WILL BE MARGINAL TO SUPPORT ANYTHING BEYOND AN ISOLATED STRONG STORM
OVER THE SOUTH. RAINFALL AMOUNTS OF A QUARTER TO HALF INCH ARE
SUPPORTED OVER ALL BUT THE FAR SOUTH...WHERE HEAVIER RAINFALL RATES
COULD RESULT IN HALF TO OVER ONE INCH TOTALS.

.LONG TERM...(THURSDAY THROUGH NEXT TUESDAY)
ISSUED AT 402 AM CDT WED OCT 1 2014

THURSDAY...VIGOROUS L/W TROF STILL ON TRACK TO PHASE/DEEPENING TOWARD
THE MS RVR VALLEY THROUGH FRI MORNING. LATEST RUNS A BIT FURTHER
EAST THAN LAST NIGHT/S RUNS WITH SFC LOW PROGRESSION UP THE WESTERN
CWA AND INTO SOUTHWESTERN WI BY THU EVENING...BUT MODEL SYNOPTIC
SCALE UPPER WAVE/TROF PLACEMENT AND EJECTING JET ENERGY SUGGEST THE
LLVL LOW MAY STILL PULL UP A BIT FURTHER NORTHWEST THAN THE LATEST
SOLUTIONS INDICATE IT WILL. STILL A LIKELY TO CATEGORICAL SHOWER
AND EMBEDDED THUNDERSTORM EVENT WITH WAVE OF ACTIVITY STREAMING UP
ACRS THE CWA ALONG AND AHEAD OF THE FRONTAL BOUNDARY AND SFC WAVE...
MOST ACTIVE WINDOW LOCALLY FROM 18Z THU THROUGH 06Z FRI OR SO.
SEASONABLY HIGH MOISTURE FEED AND PWAT/S OF 1.5 TO 1.6+ INCHES...
COMBINED WITH EXTENT OF LIFT AND DURATION OF EVENT SUGGEST THAT
MUCH OF THE CWA TO RECEIVE FROM AROUND A HALF INCH ON THE LOW END...
UP TO 1.5 INCHES BY 12Z FRI MORNING. BULK OF SHOWER ACTIVITY EXITING
THE DVN CWA AFTER MIDNIGHT THU NIGHT. THE LATEST SOLUTIONS INCLUDING
THE 00Z RUN ECMWF AND GFS SUGGEST THAT WITH SUCH A SATURATING
COLUMN AND FURTHER EAST SFC LOW TRACK...SVR STORM POTENTIAL LIMITED
AND MAY BE RESTRICTED TO THE FAR SOUTHERN AND SOUTHEASTERN CWA THU
AFTERNOON AND EARLY EVENING. DEEP CONVECTIVE INDEX FIELDS COMBINED
WITH ADEQUATE SHEAR PROFILES SUGGEST THE BEST CHANCE FOR SVR STORMS
APPEARS TO BE TO THE SOUTHWEST OF THE CWA ACRS EASTERN KS AND
WESTERN MO INITIATING POINTS...EVOLVING INTO A SQUALL LINE THAT WILL
MOVE ACRS MO AND AR INTO THU EVENING. SOME OF THIS ACTIVITY COULD
MOVE ACRS THE FAR SOUTHERN CWA LATE THU AFTERNOON AND EVENING. A
FURTHER NORTHWEST SFC LOW EJECTION THAN CURRENTLY INDICATED MAY
ALLOW FOR STRONGER STORMS FURTHER TO THE NORTH INTO THE LOCAL AREA.
LOW AND FRONTAL PLACEMENT ALONG WITH PRECIP AREAS TO BE MAJOR
TEMPERATURE FACTORS AND HIGHS FOR THU A CHALLENGE. LARGE TEMP
CONTRASTS POSSIBLE FROM NORTHWEST-TO-SOUTHEAST. LARGE POST-FRONTAL
WESTERLY WIND SURGE AND COLD AIR ADVECTION MACHINE TO SWEEP IN FROM
THE WEST LATE THU NIGHT.

FRIDAY AND SATURDAY...FRI A RAW BLUSTERY DAY WITH HIGH TEMPS
RECOVERING JUST 3-7 DEGREES FROM MORNING LOWS IN STRONG INCOMING
COLD AIR ADVECTION...HIGHS HELD IN THE 50S. 00Z MODEL RUNS SUGGEST
NEGATIVE H85 TEMPS ACRS THE CWA BY LATE AFTERNOON...ALONG WITH WRAP
AROUND SHOWERS ESPECIALLY ACRS THE NORTHERN TWO THIRDS. TIGHTENING
LLVL CYCLONIC GRADIENT TO DRIVE WINDY CONDITIONS WITH 20-30 MPH
SUSTAINED AD GUSTS UP TO 40 MPH POSSIBLE. WRAP AROUND CLOUDS AND
SCTRD SHOWERS TO CONTINUE INTO FRI NIGHT...BEFORE A POSSIBLE LATE
NIGHT CLEAR OUT. BUT SFC WINDS EXPECTED TO CONTINUE TO MAINTAIN AT
10-20 MPH INTO EARLY SAT MORNING WITH THE INHERENT MIXING KEEPING SFC
TEMPS FROM BOTTOMING OUT AT THE FULL COLD POTENTIAL. BUT COLD AIR
ADVECTION ITSELF SHOULD STILL MAKE FOR WIDESPREAD LOWS IN THE MID TO
UPPER 30S BY SAT MORNING. BLUSTERY AND CHILLY CONDITIONS TO CONTINUE
INTO SAT WITH VARYING CLOUDS AND POSSIBLY MORE COLD ALOFT INSTABILITY
SHOWERS AS THE DAY PROGRESSES. COLD POOL OVER THE REGION AND THE
CLOUDS MAY KEEP TEMPS IN THE 40S TO LOWER 50S ON SAT. DEPENDING ON
SPEED OF LLVL RETURN FLOW AND RIDGE MIGRATING ACRS THE AREA...SAT
NIGHT STILL MAY BE THE NIGHT TO WATCH FOR A POSSIBLE WIDESPREAD
FROST WITH QUICK DROP OFF AFTER SUNSET AND LOWS IN THE LOWER 30S.
OVERNIGHT TEMPS MAY STILL LEVEL OUT LATE AND START TO RISE TOWARD
DAWN SUNDAY AHEAD OF INCOMING CLIPPER EMBEDDED IN STEEP
NORTHWESTERLIES DOWN THE UPPER MS RVR VALLEY. TH CLIPPER TO
POSSIBLY BRING SHOWERS BUT ALSO WARMER TEMPS WITH IT/S ONGOING
LLVL RETURN FLOW FOR SUNDAY.

MONDAY THROUGH NEXT TUESDAY...POTENTIAL FOR ANOTHER NORTHWEST FLOW
WEAK WAVE/CLIPPER SYSTEM THIS PERIOD BEFORE MEAN STEERING FLOW STARTS
TO FLATTEN OUT TOWARD MID NEXT WEEK. HIGHS IN GENERALLY IN THE 50S TO
60S EARLY NEXT WEEK WITH LOWS IN THE 40S.    ..12..

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 648 AM CDT WED OCT 1 2014

A COMPLEX OF RAIN AND THUNDERSTORMS IS EXPECTED TO WEAKEN AS IT
MOVES INTO EASTERN IA THIS MORNING. THIS WILL LIKELY SPREAD
SHOWERS OVER THE TERMINALS FROM MID TO LATE MORNING WITH THE
DIMINISHING POTENTIAL FOR THUNDERSTORMS NOT WORTHY OF MENTION.
CIGS AND VISIBILITIES ARE LIKELY TO GO NO LOWER THAN MVFR RANGE.
LATE THIS AFTERNOON THROUGH OVERNIGHT...ADDITIONAL ROUNDS OF
SHOWERS AND THUNDERSTORMS ARE LIKELY WITH AN INCREASINGLY MOIST
ATMOSPHERE LEADING TO SOME FOG FOR OVERNIGHT. FOR NOW...THE
POTENTIAL FOR THUNDERSTORMS IS LIMITED TO THE BRL AREA...WITH FOG
ONLY SHOWN LOWERING CONDITIONS TO MVFR. THERE IS A POTENTIAL THAT
SOME SITES COULD HAVE FOG THAT COULD RESULT IN IFR OR EVEN LOW IFR
CONDITIONS LATE TONIGHT INTO EARLY THURSDAY MORNING...WHICH IS NOT
INCLUDED IN THE FORECASTS AT THIS TIME.

&&

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

$$

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






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