Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 181758
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1258 PM CDT MON AUG 18 2014

.UPDATE...
ISSUED AT 913 AM CDT MON AUG 18 2014

DENSE FOG IS HANGING AT MANY LOCATIONS ON LONGER THAN YESTERDAY...
LIKELY DUE TO THE LIGHTER LOW LEVEL WINDS. HOWEVER...SATELLITE
REVEALS ONLY HIGH CLOUDS OVER MOST OF THE AREA AND THIS SHOULD
ALLOW THE AUGUST SUNSHINE TO BURN THROUGH THE FOG. HAVE THUS
ALLOWED THE DENSE FOG ADVISORY TO EXPIRE AS SCHEDULED AT 14Z...BUT
WILL KEEP A MENTION OF FOG GOING FOR AT LEAST ANOTHER HOUR.

HAVE ALSO UPDATED THE SHORT TERM TO REMOVE THUNDERSTORM CHANCES
AS OUTSIDE OF CENTRAL AND SW WI...AREA RADARS ARE QUIET AND IT
WILL BE SEVERAL HOURS BEFORE SUFFICIENT HEATING AND INSTABILITY
BUILDS FOR NEW CONVECTION.

&&

.SYNOPSIS...
ISSUED AT 403 AM CDT MON AUG 18 2014

ANALYSIS AT 3 AM SHOWS AREAS OF FOG THAT ARE LOCALLY DENSE OVER
PORTIONS OF THE MIDWEST WITH NOWCAST TOOLS SUPPORTIVE FOG INTO
EARLY MORNING THAT MAY REQUIRE A DENSE FOG ADVISORY NEXT FEW HOURS.
CONVECTION ALONG IA/MO BORDER ALONG WITH NOWCAST TOOLS SUGGEST
LIMITED CHANCES OF PRECIPITATION UNTIL MID TO LATE PM WITH
AFTERNOON HEATING. MOISTURE POOLING OVER IOWA IS SUPPORTIVE OF
SIGNIFICANT AREAS OF SHOWERS AND STORMS LATE PM. UPSTREAM ENERGY
AND SW MONSOON SUGGESTS INCREASINGLY FAVORABLE REGIME FOR WARMER
TEMPERATURES LATE THIS WEEK WITH RISK OF HEAVY RAIN AND POSSIBLY
SEVERE WEATHER.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 403 AM CDT MON AUG 18 2014

SHORT TERM FORECAST ASSESSMENT...POOR TO FAIR (BELOW AVERAGE TO
AVERAGE) WITH MAIN ISSUE CONVECTION. TRENDS SUGGEST BL TOO MOIST
AND UNSTABLE IN SOLUTIONS SUGGESTING LIMITED CONVECTION UNTIL LATE
PM INTO EVENING. MARGINAL RISK FOR SEVERE WEATHER ALSO SUGGESTED
THOUGH STRONG STORMS MAY OCCUR IF TEMPERATURES REACH INTO THE MID
80S WITH UPPER 60 DEWPOINTS. RAIN TOTALS SHOULD VARY WIDELY IN
STORMS AND PATCHY.

TODAY...FOG SHOULD BURN OFF SIMILAR TO TODAY AROUND 9 AM WITH PARTLY
CLOUDY SKIES. UNLESS TRENDS CHANGE...MOST PRECIPITATION WILL NOT
OCCUR UNTIL CONVECTIVE TEMPERATURES ARE REACHED AROUND 3-4 PM...THEN
DEVELOP AND MOVE SE THIS EVENING. HIGHS SHOULD BE MOSTLY 80 TO 85
DEGREES ACROSS THE REGION AND A BIT HUMID.

TONIGHT...LIKELY POPS REASONABLE ALONG AND NORTH OF I-80 WITH
MOSTLY LIGHT TO MODERATE RAIN TOTALS WITH LOCALLY 1+ INCH AMOUNTS
IN THE STRONGEST STORMS. BEST CHANCES FOR STRONG TO NEAR SEVERE
STORMS EARLY TO MID EVENING WITH LOCAL TOOLS SUGGESTIVE OF GUSTY
WINDS TO 40-45 MPH AND PENNY TO NICKEL SIZED HAIL. MINS MOSTLY IN
THE MID TO UPPER 60S WITH POSSIBLY SLIGHTLY COOLER IF A MCS DOES
FORM FOR LATER SHIFTS TO MONITOR.   NICHOLS

.LONG TERM...(TUESDAY THROUGH NEXT SUNDAY)
ISSUED AT 306 AM CDT MON AUG 18 2014

TUESDAY AND WEDNESDAY...WILL WALK OUT ANY LINGERING SHOWERS AND
THUNDERSTORMS OUT OF THE EASTERN CWA BY MID TUE MORNING AS MAIN WAVE
DIGS ACRS THE GRT LKS AND A SURGE OF TEMPORARY SUBSIDENCE AND
TOP-DOWN DRYING WRAPS IN ACRS THE LOCAL AREA SOUTH OF THIS FEATURE.
AT LEAST SOME PARTIAL SUNSHINE BY AFTERNOON WITH MIXING SUPPORTS MOST
OF THE CWA WARMING INTO THE LOW TO MID 80S BY LATE AFTERNOON. IF
CLOUDS HANG ON LONGER THESE VALUES WILL BE TOO WARM. THEN BOTH THE
00Z RUN GFS AND 00Z ECMWF IN DECENT AGREEMENT OF SUGGESTING THAT
WHILE UPPER RIDGING AMPLIFIES ACRS THE NORTHERN PLAINS INTO SOUTH
CENTRAL CANADA...WEST SIDE SOUTH-WESTERLIES ORGANIZE ACRS THE LEE
ROCKIES INTO WEST CENTRAL PLAINS. MID AND UPPER LEVEL JET ENERGY
INCREASES ACRS THESE AREAS...AND LEE-SIDE LLVL CYCLOGENESIS ALSO TO
TAKE PLACE ACRS THE WESTERN PLAINS. IT/S JUST WHERE ASSOCIATED
RETURN FLOW WARM FRONT ALIGNS WITH INCREASING LLVL CONVERGENCE AND
WHERE LATE NIGHT CONVECTION FORMS ALONG/NORTH OF THIS BOUNDARY. THE
GFS KEEPS THE CWA DRY THROUGH WED MORNING WITH ACTIVITY OFF TO THE
WEST AND SOUTH...WHILE THE EURO CREEPS SOME ELEVATED SHOWERS/STORMS
INTO THE SOUTHWESTERN QUARTER OF THE CWA AFTER MIDNIGHT. THE NAM
MORE SIMILAR TO THE GFS WITH JUST SOME SECONDARY LIGHTER SHOWERS OR
EVEN JUST ELEVATED SPRINKLES MAYBE DRIFTING ACRS THE FAR SOUTHERN
FCST AREA...WILL KEEP LOW CHC POPS IN THE SOUTHWEST FOR NOW. AREAS
OF FOG POSSIBLE FURTHER TO THE NORTH BUT WILL KEEP OUT MENTION FOR
NOW. LOWS IN THE LOW TO MID 60S...EXCEPT THE FAR SOUTH MAY BE MORE
IN THE MID TO UPPER 60S. WHILE SEVERAL MODELS TRY TO RETREAT THE
FRONT NORTHWARD ACRS THE CWA ON WED...BETTER DYNAMICS AND FORCING
ROLL UP ALONG THE WESTERN FLANK OF THE NORTHERN PLAINS RIDGE. THUS
POTENTIALLY JUST A SMALL CHC FOR A FEW SCTRD SHOWERS/STORMS DURING
THE DAY ALONG THE FRONT OR MAINLY DRY...AS WELL AS BIG TEMP
CONTRAST/AND BUST POTENTIAL IN SOME AREAS/ SETTING UP FROM NORTHEAST
TO SOUTHWEST DEPENDING ON FRONTAL PLACEMENT/ADVANCEMENT. WED NIGHT
SHAPING UP TO BE THE WILD CARD WHERE A POTENTIAL RIDGE RIDING MCS
FIRES AND PROPAGATES. MCS FORCING TOOLS/PARAMETERS OF THE 00Z ECMWF
ARE THE FURTHEST NORTH/ALONG WITH WARM FRONTAL ADVANCEMENT...TAKING
BULK OF ANY MCS ACRS MN INTO WI WELL NORTH OF THE CWA...WITH JUST
SECONDARY WARM AIR ADVECTION TYPE SCTRD SHOWERS/STORMS FINGERING
DOWN ACRS THE NORTHERN AND NORTHEASTERN CWA LATER WED NIGHT INTO THU
MORNING. THE 00Z GFS IS FURTHER SOUTH AND BLOWS UP A HEAVY RAIN
PRODUCING MCS ALONG THE IA/MN BORDER WHICH THEN DUMPS DOWN
DANGEROUSLY CLOSE OR EVEN CLIPS THE FAR NORTHERN CWA BY THU MORNING.
WHEN THE MODELS ADVERTISE CONVERGENT AND ELEVATED THERMAL RIBBON
SETTING UP TO THE NORTH OF US DURING THIS KIND OF PATTERN/TIME OF
YEAR...MANY TIMES IT ENDS UP OCCURRING FURTHER TO THE SOUTH BY AT
LEAST A THIRD OF A STATE. SO AGREE MORE WITH THE GFS PLACEMENT AND
PATH...AND EVEN THIS MODEL MAY BE TOO FAR NORTH. WILL KEEP HIGH CHC
POPS GOING ACRS THE NORTH HALF FOR NOW. CURRENTLY INDICATED ELEVATED
THTA-E FEED WOULD SUGGEST SOME LOCALLY HEAVY RAINFALL POSSIBLE WITH
ANY NOCTURNAL MCS WED NIGHT INTO THU MORNING.

THURSDAY AND FRIDAY...LATEST MEDIUM RANGE MODELS SUGGEST A POTENTIAL
RING OF FIRE PATTERN SETTING UP ACRS THE MIDWEST DURING THE LATE
WEEK PERIOD...IT/S AGAIN JUST HOW FAR NORTH THE MAIN STORM TRACK
WILL SET UP THAT IS STILL VERY MUCH AT QUESTION AT THIS POINT. BULK
OF THE SOLUTIONS SUGGEST MOST OF THE CONVECTIVE FLARE UPS TO
PROPAGATE UP AND OVER THE LOCAL AREA FROM NEB...TO MN/WI AND INTO THE
GRT LKS...WHILE HEAT/90+ DEGREE TEMPS AND HUMIDITY ENGULF MUCH OF THE
SOUTHERN HALF TO 2/3S OF THE LOCAL AREA. AGAIN...DEFINITELY SOME
UNCERTAINTY OF WHERE THE MAIN STORMS TRACK WILL EVENTUALLY LAY OUT
WITH THE POTENTIAL OF IT BEING FURTHER SOUTH THEN WHAT MOST OF THE
MODELS ARE SUGGESTING. OCCASIONAL CHC POPS TO RIDE THROUGH THE
PERIOD TO COVER THIS. BIG TEMP CONTRAST POSSIBLE AS WELL FROM NORTH
TO SOUTH...AND THE CHANCE OF HEAT ADVISORY CRITERIA DEVELOPING IN
AT LEAST THE SOUTHERN PORTIONS OF THE FCST AREA BOTH THU AND FRI
AFTERNOON IF STORMS/DEBRIS SETTLE FURTHER OFF TO THE NORTH.

NEXT SATURDAY AND SUNDAY...RING OF FIRE PATTERN TO CONTINUE INTO THE
WEEKEND...WITH BLOCKED PATTERN ACRS THE CONUS. SAME CONCERNS FOR
THE THU/FRI TIME-FRAME REMAIN INTO THE WEEKEND. THE 00Z ECMWF TRIES
TO BREAK THE PATTERN BY LATE SUNDAY OR NEXT MONDAY WITH A STRONG
RIDGE RIDING WAVE...BUT DON/T TRUST THAT ENERGY INGEST THAT FAR OUT
AT THIS POINT...THE GFS MAINTAINING HEAT DOME WITH FRINGE
FIREWORKS INTO MONDAY MAY BE MORE THE WAY TO GO.    ..12..

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1258 PM CDT MON AUG 18 2014

CONDITIONS WILL IMPROVE TO VFR AT ALL SITES EARLY THIS AFTERNOON
AS LOW CLOUDS CONTINUE TO DISSIPATE AND REMAINING FOG/HAZE THINS
OUT. A WEAK UPPER LEVEL SYSTEM AND SURFACE FRONT WILL BRING A
CHANCE FOR THUNDERSTORMS LATE THIS AFTERNOON AND OVERNIGHT. THE
GREATEST CHANCE FOR THUNDERSTORMS WILL BE ACROSS THE NORTH AT CID
AND DBQ THIS EVENING...WHERE TEMPO GROUPS WERE UTILIZED.
FURTHER SOUTH...CONFIDENCE IS RATHER LOW WITH THE TIMING AND
COVERAGE OF THUNDERSTORMS AT MLI AND DBQ...WHICH IS INCLUDED WITH
ONLY PROB30 OR VICINITY WORDING. FOG MAY AGAIN FORM
TONIGHT...WITH WIDESPREAD MVFR CONDITIONS LIKELY...TRANSITIONING
TO OCCASIONAL IFR AROUND SUNRISE TUESDAY.

&&

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

$$

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






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