586
FXUS63 KDVN 231114
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
614 AM CDT TUE OCT 23 2018
..12Z AVIATION UPDATE
SYNOPSIS
ISSUED AT 223 AM CDT TUE OCT 23 2018
A WEAK COLD FRONT PASSED LAST EVENING ATTENDANT TO LOW PRESSURE
TRAVERSING SOUTHERN ONTARIO. NORTHERLY WINDS IN THE WAKE ARE
USHERING IN COOLER AIR, WITH HIGH PRESSURE BUILDING SOUTHWARD
FROM CANADA. THIS HIGH PRESSURE WILL PROVIDE DRY AND SEASONABLY
COOL CONDITIONS FOR THE NEXT SEVERAL DAYS. LATE WEEK AND THIS
WEEKEND WILL BRING INTERMITTENT LIGHT RAIN CHANCES, AS A LARGE
UPPER RIDGE BREAKS DOWN ALLOWING WEST/NORTHWEST FLOW TO SHUTTLE
IN A SERIES OF DISTURBANCES.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 223 AM CDT TUE OCT 23 2018
BENIGN WX AS HIGH PRESSURE CONTINUES BUILDING SOUTH INTO THE
MIDWEST PROVIDING GENERALLY CLEAR SKIES. HIGHS TODAY WILL BE
NOTICEABLY COOLER THAN THOSE OF MONDAY, WITH COOL AIR DEEPENING
IN THE LOWER TROPOSPHERE. HAVING SAID THAT, DRY AIR AND DRYING
GROUND ALONG WITH FULL SOLAR INSOLATION AND MIXING DRY
ADIABATICALLY TO AROUND 900 MB ALL SUPPORTIVE OF SIDING CLOSER
TO WARMER SIDE OF GUIDANCE FOR HIGHS, WITH WIDESPREAD 50S.
HIGH PRESSURE RIDGE CENTERED OVER THE AREA TONIGHT WILL PROVIDE
AN IDEAL RADIATIONAL COOLING SETUP, AND ALLOW FOR LOWS NEAR TO
JUST BELOW THE COOLER SIDE OF GUIDANCE AND MAINLY IN THE UPPER 20S
TO LOWER 30S.
LONG TERM
(WEDNESDAY THROUGH MONDAY)
ISSUED AT 223 AM CDT TUE OCT 23 2018
BELOW NORMAL TEMPERATURES WITH PRECIPITATION CHANCES FOR THE
WEEKEND.
WEDNESDAY THROUGH THURSDAY
ASSESSMENT...HIGH CONFIDENCE
DRY AND COOL CONDITIONS WILL CONTINUE WEDNESDAY THROUGH THURSDAY AS
HIGH PRESSURE REMAINS OVER THE GREAT LAKES. THE MODELS CONTINUE TO
BACK OFF ON RAIN CHANCES FOR THURSDAY.
THURSDAY NIGHT
ASSESSMENT...LOW CONFIDENCE
THE GLOBAL MODELS OFFER DIFFERING OPINIONS ON WHAT WILL OCCUR WITH
THE UPPER LEVEL DISTURBANCE MOVING THROUGH THE AREA. THE OVERALL
TREND (PER DPROG/DT) IS TO GO LIGHTER WITH ANY PRECIPITATION
AMOUNTS. THIS TREND SUGGESTS THAT THERE IS MORE DRY AIR OVER THE
AREA THAN WHAT THE MODELS THOUGHT A FEW DAYS AGO.
THE GFS IS DRY THURSDAY NIGHT WHILE THE CMC GLOBAL HAS LIGHT
PRECIPITATION OVERSPREADING MUCH OF THE AREA. THE ECMWF IS LIGHTER
THAN THE CMC GLOBAL ON PRECIPITATION, HAS LESS AREAL COVERAGE, AND
DELAYS THE ARRIVAL OF ANY PRECIPITATION UNTIL LATE THURSDAY NIGHT.
GIVEN THE MODEL DIFFERENCES, THE MODEL CONSENSUS HAS SLIGHT CHANCE
POPS ACROSS PARTS OF THE AREA.
FRIDAY ON...
FRIDAY
ASSESSMENT...MEDIUM TO HIGH CONFIDENCE
DPROG/DT TRENDS THE PAST SEVERAL RUNS HAS BEEN TO BACK OFF ON
PRECIPITATION CHANCES FOR FRIDAY AND THUS INCREASING THE PROBABILITY
OF DRY CONDITIONS. RIGHT NOW THE MODEL CONSENSUS HAS MAINLY DRY
CONDITIONS FOR THE DAYLIGHT HOURS ON FRIDAY.
FRIDAY NIGHT THROUGH SUNDAY
ASSESSMENT...MEDIUM CONFIDENCE
OVER THE WEEKEND THE GLOBAL MODELS HAVE BEEN PERSISTENT IN
INDICATING TWO SEPARATE UPPER AIR DISTURBANCES MOVING THROUGH THE
MIDWEST GENERATING PRECIPITATION. HOWEVER, THE GLOBAL MODELS
CONTINUE TO DIFFER SOMEWHAT ON TIMING AND TRACK OF THE SYSTEMS. THUS
WHILE THERE WILL BE A RISK A RAIN, THERE WILL ALSO BE PERIODS OF DRY
WEATHER OVER THE WEEKEND.
THE ECMWF BRINGS THE FIRST DISTURBANCE THROUGH THE AREA FRIDAY NIGHT
AND SATURDAY. AFTER A BRIEF BREAK SATURDAY NIGHT THE SECOND
DISTURBANCE ARRIVES FOR SUNDAY.
THE GFS HAS A WEAK SYSTEM WITH VERY LITTLE PRECIPITATION FRIDAY
NIGHT AND SATURDAY SUGGESTING MAINLY DRY CONDITIONS, FOLLOWED BY A
BREAK SATURDAY NIGHT. THE SECOND AND MORE POTENT SYSTEM ARRIVES ON
SUNDAY BRINGING A BETTER RISK OF RAIN FOR THE ENTIRE AREA.
THE CMC GLOBAL HAS THE FIRST DISTURBANCE SLOWLY MOVE THROUGH FRIDAY
NIGHT AND SATURDAY BUT IN A WEAKENING FASHION AND THUS GENERATING
VERY LITTLE PRECIPITATION. AFTER A QUIET SATURDAY EVENING, THE
SECOND AND MORE POTENT DISTURBANCE ARRIVES LATE SATURDAY NIGHT INTO
SUNDAY WITH WIDESPREAD PRECIPITATION FOR THE AREA.
GIVEN THE DIFFERENCES BETWEEN THE MODELS THE MODEL CONSENSUS HAS
SLIGHT CHANCE TO CHANCE POPS FOR THE ENTIRE AREA FRIDAY NIGHT AND
SATURDAY, SLIGHT CHANCE POPS SATURDAY NIGHT, AND CHANCE POPS ON
SUNDAY.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 614 AM CDT TUE OCT 23 2018
VFR CONDITIONS ARE EXPECTED ACROSS THE REGION OVER THE NEXT 24
HOURS. NORTHWEST WINDS AROUND 5-10 KTS WILL BECOME LIGHT AND
VARIABLE THIS EVENING AS A RIDGE OF HIGH PRESSURE MOVES OVERHEAD.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SYNOPSIS...MCCLURE
SHORT TERM...MCCLURE
LONG TERM...08
AVIATION...SPECK
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