Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 010902
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
402 AM CDT MON SEP 1 2014

.SYNOPSIS...
ISSUED AT 353 AM CDT MON SEP 1 2014

LINEAR MCS QUICKLY DECAYING WITHIN THE PAST 60 MINS... WITH
RESIDUAL OUTFLOW BOUNDARY MOVING THROUGH NORTHWEST AND WEST
CENTRAL IL COUNTIES... WITH SCATTERED STORMS JUST SOUTHEAST
OF THE QUAD CITIES. STORMS AND OUTFLOW LATE LAST EVENING AND
EARLY THIS AM PRODUCED STRONG WIND GUSTS OF 35 TO 55 MPH WITH
ISOLD SEVERE GUSTS AROUND 60 MPH. OVER WESTERN CWA SEEING WINDS
SHIFTING AROUND TO THE EAST/SOUTHEAST AND GUSTY AT 20-25+ KTS IN
SOME LOCATIONS WITH WAKE LOW. 998 MB SURFACE LOW WAS LOCATED
OVER WESTERN ONTARIO WITH COLD FRONT TRAILING THROUGH WESTERN
MN... NORTHWEST IA ON SWD TO SECONDARY LOW OVER THE OK PANHANDLE.
ALOFT...SHORTWAVE TROUGH WAS PROGRESSING EASTWARD FROM THE NORTHERN
PLAINS.

&&

.SHORT TERM...(TODAY)
ISSUED AT 353 AM CDT MON SEP 1 2014

CONVECTION TO CONTINUE WANING THROUGH DAYBREAK WHILE SHIFTING EAST...
WITH LIKELY CONTINUATION OF LIGHTER RAIN WITH ANVIL DEBRIS LIFTING
UP ACROSS CWA... WHILE MORE SHOWERS MAY DEVELOP INTO PORTIONS OF
NORTHEAST IA WITH VORT MAX AND POSITIVE VORTICITY ADVECTION. THE
AMOUNT OF REDEVELOPMENT THIS AFTN...LOCATION AND INTENSITY /SEVERE
POTENTIAL/ QUITE UNCERTAIN DUE TO COMPLEXITIES OF LINGERING CONVECTIVE
DEBRIS THIS AM... AND EXITING OUTFLOW BOUNDARY. MAIN FOCUS FOR
DEVELOPMENT THIS AFTN COULD END UP FURTHER SOUTH/EAST OF CWA ALONG
THE REMNANT OUTFLOW BOUNDARY WHERE SOME ADDITIONAL LIFT FROM RIGHT
ENTRANCE REGION OF H3 JETLET ALSO PROGGED. COLD FRONT SHOULD BE
ENTERING NORTHWEST CWA THIS AFTN AND PROGRESS SEWD EXITING THE SOUTHEAST
BY EARLY EVENING. NOT MUCH FORCING WITH FRONT ASIDE FROM WEAK LOW
LEVEL CONVERGENCE...WHICH COUPLED WITH UNCERTAINTY IN AMOUNT OF CLOUDS
AND DEGREE OF DESTABILIZATION MAKING FOR LOW CONFIDENCE ON HOW MUCH
IF ANY REDEVELOPMENT OCCURS ALONG THE COLD FRONT. SHEAR IS QUITE STRONG
BUT UNCERTAINTY WITH AMOUNT OF DESTABILIZATION LENDS TO LOW CONFIDENCE
ON SEVERE POTENTIAL ATTM. HAVE OVERALL TAPERED POPS TO CHANCE CATEGORY
THIS AM AND CONTINUE THROUGH AFTN. HIGHS TODAY CHALLENGING AS WELL AND
AS THE CONVECTIVE DEBRIS GOES...SO GOES THE TEMPS. THE LONGER THE
DEBRIS CLOUDS PERSIST THEN TEMPS LIKELY TO STAY IN THE 70S... BUT WITH
ANY SUNSHINE FOR ANY DURATION THEN SHOULD SEE SOME LOWER 80S... AND
FCST HIGHS BLENDED BETWEEN THESE TWO SCENARIOS AND THUS LEADS TO MOST
AREAS AROUND 80.

.LONG TERM...(TONIGHT THROUGH SUNDAY)
ISSUED AT 353 AM CDT MON SEP 1 2014

TONIGHT...WILL TAKE A BLEND OF SYNOPTIC SCALE FEATURES OF THE 00Z RUN
GFS AND ECMWF...AS WELL AS MCS FORCING TOOL UTILIZING PARAMETERS
OFF THE LATEST UKMET FOR THIS PERIOD. THIS THINKING GENERALLY SUGGEST
THAT AS A RATHER BROAD UPPER TROF DIGS ACRS THE MO RVR VALLEY AND
CENTRAL IA...THE MAIN SFC FRONT OR COMBO OF THAT FRONT AND LINGERING
REMNANTS OF THE CURRENT CONVECTIVE ACTIVITY OUTFLOW LAY OUT TO THE
SOUTH AND SOUTHEAST OF THE LOCAL FCST AREA FROM THE KS/OK BORDER
REGION...NORTHEASTWARD ACRS CENTRAL MO AND IL INTO NORTHERN
INDIANA. BROAD SCALE FORCING FROM THE TROF AND MID/UPPER LEVEL JETS
OVER LLVL CONVERGENT PROCESSES SUGGEST THIS WILL BE THE HOT NEW
CONVECTIVE ZONE TONIGHT. THE UKMET MCS TOOL POINTS AT AREAS FROM
SOUTHEASTERN KS...ACRS MUCH OF CENTRAL MO AND SOUTH CENTRAL IL...INTO
NORTHEASTERN IND/SE LOWER MI WHERE A COUPLE OF MCS/S OR MORE
WIDESPREAD STORM CLUSTERS WILL OCCUR FROM THIS EVENING INTO
THE OVERNIGHT. ACCEPTED LLVL BOUNDARY PLACEMENT AND VERTICAL LIFT
PROFILES SUGGESTS THAT WHILE THE BULK OF THE SIGNIFICANT CONVECTION
THIS EVENING WILL BE TO THE SOUTH/SOUTHEAST...THE SOUTHEASTERN
QUARTER TO THIRD OF THE DVN CWA WILL STILL BE AT RISK FOR SLIGHTLY
ELEVATED SHOWERS AND STORMS PROGRESSING ACRS THOSE AREAS. BULK SHEAR
PROFILES STRONG WITH THE NAM AND GFS STILL ADVERTISING VALUES OF 50-
60+ KTS...BUT ADEQUATE INSTABILITY AND LAYER LAPSE RATES FOR
WIDESPREAD SVR STORMS IN OUR AREA STILL SUSPECT AT THIS POINT AND
FEEL JUST AN ISOLATED SEVERE THREAT IN THE SOUTHERN CWA THIS EVENING.
WILL MAKE ONLY MINOR ADJUSTMENT TO ONGOING POP PLACEMENT. HEAVY RAIN
OF OVER AN INCH POSSIBLE WHERE STORMS CAN OVERRIDE BOUNDARY AND FEED
OF ELEVATED THTA-E FEED ACRS THE SOUTHERN CWA. A LOW CHC FOR AN
ISOLATED SHOWER OR EVEN A STORM ASSOCIATED WITH THE UPPER TROF
AXIS MOVING ACRS MN...TO DRIFT INTO THE NORTHERN HALF OF THE
CWA OVERNIGHT BUT WILL NOT COVER THIS POTENTIAL WITH MENTIONABLE POPS
AT THIS POINT. AS FOR TEMPS...COOLER TONIGHT WITH LOWS IN THE UPPER
50S IN THE NORTHWEST...TO THE LOWER TO MID 60S IN THE SOUTH.

TUESDAY THROUGH FRIDAY...UPPER TROF TO MOVE ALONG EASTWARD FOR
EVENTUAL FLATTENING FLOW AND MODERATING TEMPS THIS PERIOD ACRS THE
MID CONUS. GULF OF AK WAVE INGEST ACRS WESTERN CANADA AND
EVENTUALLY INTO THE CONUS FLOW SUGGEST TROFFINESS TO RE-ESTABLISH
ACRS THE NORTHERN ROCKIES BY MID WEEK. INITIAL ELEVATED RETURN FLOW
SIGNAL MAY INDUCE SOME/WINGS OF RETURN FLOW SHOWERS OR STORMS WED OR
WED NIGHT AND WILL CARRY LOW CHC POPS FOR THIS PROCESS...BUT THIS
ACTIVITY MAY BE LIMITED AND MUCH OF THE CWA POSSIBLY TO REMAIN
DRY. HIGH TEMPS BY WED BACK ABOVE NORMAL...WITH A RETURN TO FULL
BLOWN SOUTHERLIES MAKING FOR A VERY WARM THU IN THE MID 80S TO NEAR
90. IF SFC DPTS CAN CLOSE IN ON AROUND 70 AGAIN...SOME HEAT INDICES
NEARING 100 DEGREES POSSIBLE IN THE LOCAL AREA. THE UPSTREAM L/W
TROF WILL EVENTUALLY LOOK TO SHEAR ACRS THE UPPER MIDWEST...AND
ASSOCIATED SFC FRONT MAKING A PUSH INTO THE GRT LKS THROUGH SOUTHERN
PLAINS. THE 00Z GFS AND ECMWF ACTUALLY IN DECENT AGREEMENT AND
SUGGEST THIS FROPA AND NEXT MORE ORGANIZED PRECIP CHANCE TO OCCUR THU
NIGHT INTO FRI.

NEXT SATURDAY AND SUNDAY...LONG RANGE TRENDS AND INDICATIONS SUGGEST
COOLING BACKDOOR TYPE LLVL ANTICYCLONE COMPLEX TO BUILD DOWN ACRS
THE GRT LKS AND SHUNT ACTIVE BOUNDARY ZONE WELL SOUTH OF THE AREA
THIS PERIOD FOR A MAINLY DRY FCST WITH HIGHS IN THE 70S. SAT NIGHT
RIGHT NOW LOOKS CLEAR AND COOL WITH H85 MB RIDGE COOL RULE
SUGGESTING LOWS POSSIBLY DIPPING DOWN INTO AT LEAST THE UPPER 40S IN
SOME SPOTS NORTH OF I80 BY EARLY SUNDAY MORNING.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 353 AM CDT MON SEP 1 2014

STORMS WILL CONTINUE TO SHIFT EAST OF THE TERMINALS EARLY THIS AM
WITH SOME LINGERING LIGHTER RAIN... AND POSSIBLY A FEW SHOWERS WITH
MVFR TO VFR CONDITIONS. COLD FRONT WILL MOVE THROUGH THE TERMINALS
THIS AFTN. CONSIDERABLE UNCERTAINTY EXISTS WITH AMOUNT OF REDEVELOPMENT
OF SHOWERS AND STORMS ALONG THE FRONT WITH WEAK CONVERGENCE AND MAIN
FORCING TIED TO OUTFLOW BOUNDARY FURTHER SOUTH/EAST OF TERMINALS...THUS
HAVE HELD OUT ANY MENTION OF PCPN THIS AFTN AT THE TERMINALS FOR NOW.

&&

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

$$

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





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