Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 310909
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
409 AM CDT SUN AUG 31 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT SUN AUG 31 2014

TODAY...AREAS OF...TO PATCHY FOG TO CONTINUE THROUGH AT LEAST 14Z THIS
MORNING WITH NATURE OF MOST OF IT SHALLOW OR LOW BASED LAYER FOG. BUT
SOME OF IT DENSE AND WILL PUT OUT AT LEAST A SPECIAL WX STATEMENT FOR
EARLY MORNING TRAVEL. OTHERWISE...LLVL RIDGE WILL START TO MIGRATE
EASTWARD TODAY WHILE UPPER RIDGE CURRENTLY BULGING ACRS THE MID TO
UPPER MS RVR VALLEY WILL GRADUALLY TRANSITION CYCLONIC SOUTH-
WESTERLIES BY MID THIS EVENING. STILL SIGNS OF A LEAD ELEVATED WARM
AIR ADVECTION WING ON ORGANIZING SOUTHWESTERLY H85 MB JET OF 30-40
KTS ACRS NORTH CENTRAL INTO NORTHEASTERN IA THIS MORNING INTO EARLY
AFTERNOON. A FEW OF THE HIRES SOLUTIONS SUGGEST ISOLATED TO WDLY
SCTRD SHOWERS MAY POP UP ACRS THE NORTHERN CWA THROUGH MIDDAY...BUT
WITH LINGERING UPPER RIDGING WILL JUST RAISE NON-MENTIONABLE POPS FOR
NOW AND KEEP THE FCST DRY. OTHERWISE A MAINLY SUNNY AND WARM DAY ON
TAP WITH MIXING LLVL SOUTHERLIES TO BASE OF H85 MB INVERSION SUPPORT
HIGHS IN THE MID TO UPPER 80S ACRS MOST OF THE LOCAL FCST AREA.

TONIGHT...DIGGING UPSTREAM TROF CURRENTLY SEEN ON WATER VAPOR IMAGERY
ACRS THE WEST CENTRAL ROCKIES WILL LOOK TO SHEAR ACRS THE MO RVR
VALLY THIS EVENING. STRONG LLVL THTA-E FEED AND BUILDING INSTABILITY
UP INTO THE LEE OF THIS PROCESS...AS WELL AS SEVERAL MODEL INDICATED
MCS FORCING TOOL SUGGEST CONVECTION TO REALLY BLOSSOM ACRS THE EAST
CENTRAL PLAINS UP INTO MN LATER THIS AFTERNOON AND EVENING...
NORTHEASTERN KS ACRS THE WESTERN THIRD OF IA AND TOWARD THE MSP MN
AREA. STRONG SOUTHWESTERLY LLVL FEED OF 30-45 KTS AND FORCING OF THE
MID AND UPPER TROF ITSELF SHOULD ALLOW FOR STORMS CLUSTERS OR AN
EVENTUAL MCS/POSSIBLY LINEAR IN NATURE LOOKING AT STRONG LOW TO MID
LEVEL SHEAR PROFILES/ TO PROPAGATES EASTWARD INTO THE DVN CWA FROM
LATE EVENING AND ESPECIALLY AFTER MIDNIGHT. IF SYSTEM IS MATURE AS
IT ENTERS THE CWA...THERE STILL MAY BE A DAMAGING WIND THREAT EVEN
LATER AT NIGHT. BUT SOME OTHER MIXED SIGNALS BY THE 00Z SOLUTIONS
SUGGEST ONE BETTER FORCED STORM CLUSTER MAY MOVE TO THE NORTH OF THE
AREA ALONG THE IA/MN BORDER INTO SOUTHEASTERN MN INTO WI THROUGH MON
MORNING...AND ANOTHER COMPLEX OR MCS PASSING ACRS THE NORTH HALF OF
MO. THIS COULD LEAD TO SECONDARY AND WEAKENING STORM CLUSTERS OR
LINES OF STORMS MOVING ACRS THE LOCAL FCST AREA IN BETWEEN THE TWO
HOTTER ZONES. THE 00Z NAM AND GFS MAY BE ADVERTISING TOO STRONG OF
LLVL SHEAR VERTICAL PROFILES LATER TONIGHT...BUT INCOMING MESOSCALE
WIND FLOW TRENDS WILL HALF TO BE MONITORED. BUT WITH THE POTENTIAL
AND VARIANCES IN MODEL DETAILS...WILL KEEP HIGH POPS GOING AFTER
MIDNIGHT AND INTO EARLY MON MORNING SPREADING IN FROM THE WEST.
UNLESS WE GET THE WEAKENING STORM LINE SCENARIO...ANOTHER CHANCE FOR
SOME LOCALLY HEAVY RAIN LATER TONIGHT WITH SOME AREAS POSSIBLY
RECEIVING OVER AN INCH OF RAIN BY SUNRISE MONDAY. TAKING INTO ACCOUNT
THE POSSIBILITY OF RAIN COOLED SFC OUTFLOW IN SOME AREAS WHILE OTHER
AREAS MAY GET MISSED...LOWS TONIGHT TO GENERALLY VARY FROM THE MID
60S TO LOWER 70S.    ..12..


.LONG TERM...(MONDAY THROUGH NEXT SATURDAY)
ISSUED AT 406 AM CDT SUN AUG 31 2014

MON-MON NGT... ANTICIPATE WEAKENING THUNDERSTORM COMPLEX MOVING ACROSS
CWA MON AM. SHORTWAVE TROUGH IS SHOWN TO SHIFT FROM THE UPPER MIDWEST
INTO THE GREAT LAKES BY LATE IN THE DAY USHERING IN A COLD FRONT. THE
COLD FRONT OR EFFECTIVE BOUNDARY FROM MORNING STORMS MAY SERVE AS
A FOCAL POINT FOR RE-DEVELOPMENT OF STORMS BY MID TO LATE PM. MODERATE
CAPE (1500-2500 J/KG) AND STRONG/HIGH 0-6KM SHEAR (40+ KTS) SUPPORTIVE
OF ORGANIZED SEVERE STORMS. HOWEVER... RISK OF SEVERE CONDITIONAL
DUE TO UNCERTAINTY WITH DEGREE OF DESTABILIZATION (CLOUDS AND PCPN
MAY LIMIT)... WEAK FRONTAL CONVERGENCE... AND MAIN UPPER LEVEL FORCING
PASSING N/NE OF THE CWA. WITH SUFFICIENT DESTABILIZATION... AND
FORCING AIDED BY 300 MB 80-90+ KT JET... THEN WOULD ANTICIPATE AT LEAST
SCATTERED STORMS DEVELOPING AHEAD OF FRONT/EFFECTIVE BOUNDARY BY MID-LATE
PM. FORCING ALIGNED PARALLEL TO FRONT SUGGESTIVE OF FAIRLY SHORT-LIVED
SUPERCELL STRUCTURES WITH HAIL AND/OR WIND BEFORE TRANSITION TO A LINE
WITH WIND THREAT WITH SOME EMBEDDED BOWING SEGMENTS. PWATS OF 1.5-2 INCHES
WITH DEEP WARM CLOUD DEPTHS SUGGESTIVE OF LOCALLY HEAVY RAINS POSSIBLE...
BUT STORMS SHOULD BE MOVING QUICKLY TO LIMIT RAINFALL TO MAINLY 0.5 INCH
OR LESS. ONCE AGAIN... THE SEVERE RISK FOR MONDAY PM IS CONDITIONAL UPON
SUFFICIENT HEATING/DESTABILIZATION AND FORCING. MON NGT WILL SEE MAIN
CHANCES FOR SHOWERS AND STORMS EXIST ACROSS THE SOUTHERN CWA BEING IN
CLOSER PROXIMITY TO BOUNDARY AND STRENGTHENING NOCTURNAL LOW LEVEL JET.
LOWS MON NGT COOLEST NORTHWEST CWA (55-60F) TO WARMEST FAR SOUTH/SOUTHEAST
(MID 60S).

TUE-TUE NGT... TRENDING DRIER WITH FRONT OR EFFECTIVE BOUNDARY SOUTH OF
THE CWA AND WEAK SURFACE HIGH TRAVERSING THE REGION. HIGHS MAINLY
AROUND 80 OR LOWER 80S... WHILE LOWS TUE NGT IN THE UPPER 50S TO LOWER 60S.

WED-SAT... SHOWER AND STORM CHANCES WILL RETURN DURING THE PERIOD. MAIN
CHALLENGE WILL BE TIMING THESE RAIN CHANCES DUE TO CONTINUED MEDIUM
RANGE MODEL RUN TO RUN VARIANCES WITH LOCATION/MOVEMENT OF FRONT AND TIMING
OF UPPER LEVEL DISTURBANCES. OVERALL...WOULD APPEAR TARGETING WED NGT-THU
FOR FIRST RAIN CHANCES WITH FRONT LIFTING BACK NORTHWARD THROUGH THE REGION.
THEN...MAY SEE PERIOD OF CAPPING AND DIMINISHED CHANCES BY LATE THU PM
INTO EARLY FRI WITH BOUNDARY TO OUR NORTH AND AMPLIFYING UPPER LEVEL RIDGE
OVER THE CENTRAL US. LATE WEEK THEN WOULD APPEAR TO BRING NEXT CHANCE
OF PCPN WITH FRONT RETURNING BACK SOUTH AS COLD FRONT AS UPPER LEVEL TROUGH
SHIFTS ACROSS THE UPPER MIDWEST INTO THE GREAT LAKES. TEMPS TO FLUCTUATE
A BIT WITH A DAY OR TWO OF ABOVE NORMAL READINGS MID-LATE WEEK BEFORE
TRENDING NEAR TO BELOW NORMAL NEXT WEEKEND WITH COOLER CANADIAN HIGH SETTLING
IN.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1137 PM CDT SAT AUG 30 2014

EXPECT MVFR VSBYS DEVELOPING OVERNIGHT WITH A CLEARING SKY AND
LIGHT WIND. PERIODS OF LIFR/IFR VISIBILITIES AND/OR CEILINGS
ANTICIPATED FROM 09Z-13Z. LATE IN THE PERIOD...A THUNDERSTORM
COMPLEX WILL LIKELY BE APPROACHING EASTERN IOWA. WILL INTRODUCE A
VCTS GROUP AT 04Z SUNDAY NIGHT...AND KEPT REST OF TAF SITES DRY
THROUGH 06Z.

&&

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

$$

SHORT TERM...12
LONG TERM...05
AVIATION...RP KINNEY





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