671
FXUS63 KDVN 172309
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
609 PM CDT FRI AUG 17 2018
..AVIATION UPDATE
SYNOPSIS
ISSUED AT 329 PM CDT FRI AUG 17 2018
UPPER LEVEL TROF AXIS WAS MIGRATING EASTWARD ACRS NORTHERN IL ATTM,
WITH IT'S SIGHTS SET ON LOWER MI INTO NORTHWEST IN BY THIS EVENING.
VORT SPOKES ROTATING AROUND THIS FEATURE COMBINING WITH AFTERNOON
HEATING TO PRODUCE ANOTHER AFTERNOON OF SCTRD SHOWERS AND A FEW
THUNDERSTORMS. AFTER THIS TROF GETS OUT OF THE WAY, A BOUT OF
RIDGING TO MAKE FOR A FAIR AND SEASONABLY WARM WEEKEND, BEFORE THE
NEXT WAVE(NOW OVER THE PACIFIC NW) ROLLS INLAND AND ACRS THE MID
CONUS FOR ANOTHER ROUND OF RAIN FOR THE LOCAL AREA STARTING LATER
SUNDAY NIGHT AND LASTING INTO EARLY NEXT WEEK.
SHORT TERM
(THIS EVENING THROUGH SATURDAY)
ISSUED AT 329 PM CDT FRI AUG 17 2018
TONIGHT...WILL DECREASE POPS AND COVERAGE OF SCTRD SHOWERS AND A FEW
STORMS AS THE EVENING PROGRESSES THROUGH SUNSET AND BEYOND. UNTIL
THEN, THE MORE VIGOROUS SHOWERS WILL UTILIZE ONGOING HIGH PRECIPITAL
WATER(PWATS) OF 1.6 TO 1.7+ INCHES TO PRODUCE LOCALLY HEAVY
DOWNPOURS AND RAINFALL. THE SHOWER AND STORM CLUSTER NOW ACRS
CENTRAL INTO SOUTHWESTERN WI MAY GET INTO THE NORTHWESTERN CWA LATE
THIS AFTERNOON AND EARLY EVENING BEFORE DECREASING. ONGOING UPPER
LEVEL LOW DYNAMICS AS WELL AS LLVL VORTICITY , LOW LCL'S AND
INSTABILITY WILL ALSO KEEP THE CHANCE OF NON-SUPERCELL FUNNEL CLOUDS
GOING THROUGH EARLY EVENING, ALTHOUGH AREAS MORE PRIME FOR THAT
PHENOMENA APPEAR TO BE TO THE EAST OF THE AREA CLOSER TO THE UPPER
LOW CENTER. THEN CLOUD COVER WILL LOOK TO DECAY DIURNALLY OVERNIGHT,
AND WITH ONGOING RATHER MOIST SFC LAYER/ LINGERING HIGH SFC DPTS
WITH LIGHT NORTHEAST WINDS, ANOTHER ROUND OF PATCHY TO AREAS OF
DENSE FOG POSSIBLE LATE TONIGHT INTO EARLY SAT MORNING. WILL GO WITH
WIDESPREAD LOWS IN THE MID TO UPPER 60S, OR SIMILAR LOWS TO WHAT
OCCURRED THIS MORNING IN MOST AREAS.
SATURDAY...ANOTHER MORNING OF WHATEVER FOG AND LOW STRATUS/STRATOCU
LIFTING INTO A LOW CLOUD DECK FOR PART OF THE MORNING, BUT THEN MORE
SUBSIDENCE WITH UPPER RIDGING TAKING OVER TO CLEAR THINGS OUT BY
LATE MORNING. STILL SOME SUPPORT(CU RULE ALSO AGREES)FOR AMBIENT
DIURNAL CU FORMATION(OR MAINTENANCE FROM THE MORNING) OF AT LEAST
SCTRD CU COVERAGE DURING THE AFTERNOON. BUT THIS SHOULD STILL MEAN
MOSTLY SUNNY SKIES FOR MOST OF THE AREA. A FEW MODELS LIKE THE 12Z
RUN NAMNEST AND GFS BREAK OUT ISOLATED SHOWERS IN A CONVERGENT ZONE
SOUTHWEST OF DUBUQUE OR ACRS THE NORTHWESTERN THIRD OF THE CWA BY
SAT AFTERNOON, BUT LOW CONFIDENCE IN THIS AND WILL KEEP THE FCST DRY
FOR NOW. ..12..
LONG TERM
(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 329 PM CDT FRI AUG 17 2018
MAIN FOCUS IS POTENTIAL FOR WIDESPREAD SOAKING RAINS EARLY NEXT
WEEK WITH THE LAST AND POTENTIALLY STRONGEST IN A SERIES OF RECENT
STORM SYSTEMS.
THIS WEEKEND... GENERALLY DRY, AND SEASONABLY WARM AND HUMID WITH WEAK
GREAT LAKES RIDGING THE DOMINANT WEATHER FEATURE. EACH AFTERNOON WILL
HARBOR VERY ISOLATED SHOWER/WEAK STORM POTENTIAL WITH CONVECTIVE
TEMPERATURES BREACHED. LACK OF ANY FORCING OF NOTE MAKES COVERAGE TOO
LIMITED FOR ANY MENTION. HIGHS MOSTLY MID/UPPER 80S - NEAR TO A LITTLE
ABOVE NORMAL.
EARLY NEXT WEEK... CONTINUE TO SEE ENCOURAGING SIGNAL FOR WIDESPREAD
RAINFALL ON MONDAY, AS STRONGER SOUTHERN STREAM SHORTWAVE POTENTIALLY
PHASES WITH NORTHERN STREAM ENERGY FOR DECENT FORCING WITH ATTENDANT
DEFORMATION ZONE. MAGNITUDE OF FORCING, AND DECENT MOISTURE ADVECTION
WITH SOME GULF AND POTENTIAL MONSOONAL FETCH WOULD BE SUPPORTIVE OF
MODERATE TO AREAS OF HEAVY RAINFALL. HOWEVER, LOCATION OR MOST FAVORED
AREAS STILL IN QUESTION DUE TO UNCERTAINTIES ON TRACK/STRENGTH OF SYSTEM
BUT DESPITE THIS BELIEVE MANY AREAS IN LINE FOR A LEAST SOME RAINFALL.
SEVERE WEATHER POTENTIAL LOOKS RATHER LOW WITH FAIRLY MOIST SOUNDINGS
AND LIMITED INSTABILITY/SHEAR.
MAY SEE SOME SHOWER CHANCES LINGER TUESDAY WITH ADDITIONAL ENERGY
DROPPING DOWN ON BACKSIDE OF DEPARTING SYSTEM. THEN, GENERALLY DRY AND
QUIET FOR MUCH OF THE REST OF THE WEEK WITH THE NEXT RAIN CHANCE
PERHAPS ARRIVING TOWARD THE WEEKEND. TEMPERATURES LOOK TO DIP NEAR TO
SLIGHTLY BELOW NORMAL THROUGH MIDWEEK IN NORTHWEST FLOW, WITH HIGHS IN
THE UPPER 70S TO LOWER 80S AND LOWS IN THE 50S. BY NEXT WEEKEND SHOULD
SEE MODERATION OF TEMPERATURES NEAR NORMAL IN DEVELOPING ZONAL FLOW.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 603 PM CDT FRI AUG 17 2018
THE REGION WILL REMAIN ON THE EDGE OF AN UPPER LOW PRESSURE SYSTEM
THIS EVENING, WITH A FEW SHOWERS ROTATING SOUTH OVER THE AREA.
THESE ARE ISOLATED ENOUGH NOT TO BE INCLUDED IN THE 00Z TAF SET.
OVERNIGHT, SKIES WILL BE CLEAR INITIALLY THEN GROUND FOG FORMATION
WILL ONCE AGAIN BE POSSIBLE THROUGH ABOUT 13 OR 14Z SATURDAY.
SATURDAY WILL BE VFR WITH LIGHT WINDS AND SCATTERED CUMULUS.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SYNOPSIS...12
SHORT TERM...12
LONG TERM...05
AVIATION...ERVIN
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