Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 171725
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1225 PM CDT SUN AUG 17 2014

.UPDATE...
ISSUED AT 1224 PM CDT SUN AUG 17 2014

EARLY MORNING FOG HAS DISSIPATED AS EXPECTED...BUT THE LINGERING
LOW LEVEL MOISTURE AND WEAK EASTERLY FLOW IS KEEPING PLENTY OF LOW
CLOUD COVER OVER THE REGION AS OF MIDDAY. OVERALL...MOST AREAS
SHOULD SEE AT LEAST SOME SUNSHINE BY LATE AFTERNOON AS THE MOISTURE
PARTIALLY MIXES OUT WITH THE FAR NORTH AND FAR SOUTH AND SOUTHEAST
SLOWEST TO IMPROVE. HAVE MADE ONLY MINOR TWEAKS TO THE FORECAST
WITH ANTICIPATED HIGHS FROM THE UPPER 70S TO LOWER 80S STILL
LOOKING PLAUSIBLE.

&&

.SYNOPSIS...
ISSUED AT 244 AM CDT SUN AUG 17 2014

THE UPPER LEVEL LOW RESPONSIBLE FOR THE HEAVY RAIN ACROSS THE
EXTREME SOUTHWEST PART OF OUR CWA IS SLOWLY DRIFTING EAST
SOUTHEAST. A FEW SPRINKLES ARE JUST SOUTHEAST OF THE CWA...
OTHERWISE THE ONLY IMPACT FROM THIS SYSTEM IS LINGERING CLOUDS
ACROSS THE SOUTHERN PART OF THE CWA. TO THE NORTH WHERE CLOUDS ARE
THINNER...FOG HAS BEEN DEVELOPING. VISIBILITIES ARE FLUCTUATING BUT
THERE ARE POCKETS OF DENSE FOG BEING OBSERVED. AS THE LOW
CONTINUES ITS DEPARTURE...A SHORTWAVE RIDGE WILL BUILD OVER THE
AREA EVEN AS A WEAK DISTURBANCE MOVES TO OUR NORTH TODAY. A WEAK
SURFACE BOUNDARY/BACK DOOR COLD FRONT HAS BEEN MOVING SOUTHWARD
ACROSS WI OVERNIGHT AND IS NOW IN THE SOUTHERN PART OF THE STATE
APPROACHING THE IL BORDER AT 08Z.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 244 AM CDT SUN AUG 17 2014

FOG...LOCALLY DENSE...THIS MORNING SHOULD BE SHORT-LIVED AND BURN
OFF BETWEEN 8 AND 10 AM. AT THIS POINT I DO NOT EXPECT DENSE FOG
TO BECOME SUFFICIENTLY WIDESPREAD TO ISSUE AN ADVISORY. WILL
HANDLE WITH SPSS.

AS THE UPPER LOW DRIFTS SOUTHEAST OUR PRECIP CHANCES DIMINISH
RAPIDLY EARLY THIS MORNING. MODELS CONCUR ON MOVING A WEAK
SHORTWAVE TO OUR NORTH LATER THIS AFTERNOON. THE 00Z NAM IS MORE
AGGRESSIVE WITH THE STRENGTH AND QPF WITH THIS SYSTEM...BUT IT IS
AN OUTLIER. SO FAVORED THE OTHER MODELS THUS THE FORECAST IS DRY
TODAY AND TONIGHT. HOWEVER ONE CANNOT RULE OUT AN ISOLATED
SHOWER/STORM AS THE BOUNDARY FROM WI WORKS INTO THE CWA AND
POSSIBLY FIRES UP A STORM AS THE WEAK VORT MAX WORKS ACROSS THE
AREA.

MAX TEMPS TODAY SHOULD BE AT OR ABOVE YESTERDAY/S MAX TEMPS WITH
MORE SUNSHINE THAN YESTERDAY. HIGHS WILL BE TEMPERED SLIGHTLY BY
THE BACKDOOR COLD FRONT...AND CLOUD COVER IN THE SOUTH WILL HOLD
TEMPS DOWN A BIT. LOWS OVERNIGHT WILL BE NEAR SEASONAL VALUES.
WOLF

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 244 AM CDT SUN AUG 17 2014

INCREASINGLY UNSETTLED WEATHER WITH POTENTIAL FOR SIGNIFICANT
RAINFALL MID TO LATE NEXT WEEK...THEN VERY WARM AND HUMID.

OVERVIEW...INITIALIZATION AND VERIFICATION AGAIN GOOD TO VERY GOOD
WITH NOMINAL MOISTURE BUDGET ISSUES WITH MODEL DEWPOINTS TENDING
TO BE A FEW DEGREES TOO HIGH. D-PROG/DT OF SOLUTIONS SUGGESTS
GOOD (LIMITED) INTER MODEL VARIANCE AND ADD WITH VERIFICATION A
60/40 MIX OF GFS TO GEM-NH/HI-RES ECMWF IS SUGGESTED BEST FIT.
THIS WITH STALLED BOUNDARY MID TO LATE NEXT WEEK AND BUILDING
SOUTH PLAINS HEAT FAVORABLE TO RESULT IN ONE OR MORE SIGNIFICANT
CONVECTIVE EVENTS WITH HEAVY TO VERY HEAVY RAIN POTENTIAL. TIMING
AND LOCATIONS IMPACTED BETTER KNOWN THE NEXT 24 TO 48 HOURS WITH
GOOD OUTFLOW BOUNDARIES THAT MODELS CAN/T CAPTURE DIRECTLY DUE TO
THIS IS A NON-HYDROSTATIC PROCESS.

LONG TERM FORECAST ASSESSMENT CONFIDENCE...AVERAGE TO ABOVE AVERAGE
(GOOD TO VERY GOOD)...MAIN ISSUES ARE SPECIFIC TIMING AND COVERAGE OF
AREAS OF SHOWERS AND STORMS LATE MONDAY WITH MOSTLY LIGHT TO MODERATE
RAIN TOTALS WITH ABOVE AVERAGE CONFIDENCE. INCREASING RISK OF SIGNIFICANT
CONVECTIVE EVENTS MID/LATE NEXT WEEK ARE AVERAGE AT MOST WITH TIMING
AND COVERAGE THE ISSUES AS MENTIONED ABOVE. NORMAL TEMPERATURES WITHIN
3 DEGREES MOST PERIODS EXCEPT WHERE CLOUDS AND PRECIPITATION OCCUR
WHICH NORMAL SUMMERTIME CONFIDENCE ISSUES WERE JUST DESCRIBED,

MONDAY...GENERALLY FAIR AND SEASONABLY WARM WITH HIGHS 80 TO 85 WITH
LOW PM PRECIPITATION RISKS AS NEXT DISTURBANCE FROM NORTH PLAINS APPROACHES
UNTIL LATE PM NW SECTIONS. MONDAY NIGHT...SLIGHTLY RAISED POPS AS DIGGING
UPPER TROUGH FORCING AND MOISTURE SUPPORTS CATEGORICAL POPS FOR LATER
SHIFTS TO CONSIDER. GENERAL AMOUNTS OF A HALF INCH OR LESS MOST AREAS
WITH ISOLATED 1 INCH AMOUNTS POSSIBLE WITH STRONGEST STORMS. ISOLATED
STRONG STORMS INTO LATE EVENING ALSO SUGGESTED WITH GUSTY WINDS TO
AROUND 40 MPH AND SOME PEA SIZED HAIL. MONDAY NIGHT LOWS IN THE MIDDLE
60S.

TUESDAY...MORNING LOW CHANCE POPS MAY BE ABLE TO BE REMOVED BY LATER
SHIFTS AS UPPER TROUGH MOVES EAST. ANOTHER SEASONAL AUGUST DAY WITH
HIGHS IN THE LOWER 80S AND LOWS IN THE MIDDLE 60S.

WEDNESDAY...LOW POPS MOST AREAS AS WEAK BOUNDARY MOVES NORTH TOWARD
AREA AS SOUTH PLAINS HEAT BUILDS WITH HIGHS MOSTLY IN THE MIDDLE
80S FOR MOSTLY LATE PM CONVECTION. WEDNESDAY NIGHT...BOUNDARY AND
LOW LEVEL JET AND UPPER DIFLUENCE SUPPORTIVE OF CONVECTIVE SYSTEM
TO ARRIVE FROM WEST/SOUTHWEST. PW/S ABOVE 1.5 TO NEAR 2 INCHES
SUPPORTS HEAVY RAIN RISKS.

THURSDAY AND FRIDAY...EAST WEST BOUNDARY AND LOW LEVEL JET AREA FAVORABLE
FOR HIGHER POPS WITH HEAVY RAIN RISKS AND EVEN ISOLATED SEVERE. LOCAL
TOOLS SUGGESTS 2 TO 5 PLUS INCH RAINS POSSIBLE WITHIN TRAINING PATHS
AND GUSTY WINDS TO LOCALLY AROUND 60 MPH LATE PM AND POSSIBLY HAIL.
OUTFLOW BOUNDARIES WILL OCCUR WITH DEWPOINTS AOA 70F AND WIND SHEAR
MODEST AT MOST. THUS...LOCATIONS AND IMPACTS ON TEMPERATURES WILL
BE LARGE. BEST COURSE ACTION IS GOING WITH UPPER 80S FOR HIGHS BUT
HIGHS MAY BE A CATEGORY OR TWO TOO HIGH IF HAVE CLOUDS...PRECIPITATION
AND GOOD OUTFLOW BOUNDARY. AFTERNOON HEAT INDICES MAY APPROACH 100F
FOR A FEW HOURS IN SOUTH SECTIONS THAT ARE NOT IMPACTED BY OUTFLOW
BOUNDARIES. AREA LOWS 65 TO 70F SUGGESTED UNLESS STRONG OUTFLOW BOUNDARY
OCCURS THAT MAY LOWER MINS A FEW DEGREES. WILL MENTION HEAVY RAIN RISKS
IN HWO PRODUCT AS CONFIDENCE HIGH ENOUGH.

SATURDAY...TRENDS SUGGEST AREA TO BE SOUTH OF WARM FRONT WITH HIGHS
UPPER 80S TO LOWER 90S FOR LATER SHIFTS TO REASSESS. LOW POPS IN
NORTH AS WARM FRONT WILL BE NEAR. MINS SUNDAY MORNING SUGGESTED TO
BE MUGGY...AROUND 70F TO LOWER 70S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1224 PM CDT SUN AUG 17 2014

WEAK WEATHER FEATURES WITH LIGHT WINDS AND HIGH LEVELS OF LOW
LEVEL MOISTURE WILL LEAD TO ANOTHER NIGHT OF DETERIORATING FLIGHT
CONDITIONS AS LOW CLOUDS AND FOG RETURN. THIS AFTERNOON...CLOUD
BASES WILL CONTINUE TO LIFT...RISING ABOVE MVFR THRESHOLDS AT
MOST SITES BY LATE AFTERNOON. TONIGHT...MVFR CONDITIONS IN THE
FORM OF FOG WILL LIKELY RETURN AROUND MIDNIGHT. FOG WILL LIKELY
THICKEN TO IFR...FOLLOWED BY PERIODS OF LIFR AROUND SUNRISE DUE
BOTH FOG AND DEVELOPING LOW CLOUDS...WHICH HAS BEEN TRENDED IN THE
FORECASTS. AFTER SUNRISE...GRADUAL IMPROVEMENT IS EXPECTED WITH
MVFR CONDITIONS LIKELY BY 15Z.

&&

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

$$

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






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