Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 060445
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1145 PM CDT SUN JUL 5 2015

.SYNOPSIS...
ISSUED AT 320 PM CDT SUN JUL 5 2015

A SOUTHERLY BREEZE WAS TRANSPORTING WARM AND INCREASINGLY HUMID AIR
INTO THE REGION THROUGH EARLY AFTERNOON. TEMPERATURES MOST LOCATIONS
WERE IN THE 80 TO 85 DEGREE RANGE. PERSISTENT HAZE FROM CANADIAN
WILDFIRES LINGERED...IN ADDITION TO SCATTERED FAIR WEATHER CUMULUS
CLOUDS.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 320 PM CDT SUN JUL 5 2015

THE MAIN FORECAST ISSUE IN THE SHORT TERM PERIOD IS THE TIMING OF A
COLD FRONT MONDAY AND ASSOCIATED SEVERE STORM/HEAVY RAIN POTENTIAL.

FOR TONIGHT...INCREASED WAA WITH SLIGHTLY STRONGER SOUTHERLY WINDS
SHOULD KEEP LOWS UP IN THE MID 60S TO NEAR 70 DEGREES...WITH A
TYPICAL NE TO SW GRADIENT. LIGHT FOG IS AGAIN EXPECTED...NONE OF THE
DENSE VARIETY.

FOR MONDAY...THE OVERALL MODEL TREND HAS BEEN TO SLOW THE EASTWARD
PROGRESS OF A COLD FRONT. THE WRF CONTINUES TO BE AMONG THE SLOWER
SOLUTIONS...AND WOULD KEEP THE ENTIRE FORECAST AREA DRY UNTIL MONDAY
AFTERNOON. HAVE TRENDED HOURLY POPS FASTER THAN THE WRF...BUT A BIT
SLOWER THAN THE ECMWF/GFS. LOOKING AT THE HEAVY RAIN
PARAMETERS...THE WRF IS GENERATING MAX PRECIPITABLE WATER VALUES
NEAR 2.75 INCHES ALONG THE NARROW MOISTURE CONVERGENCE AXIS...LIKELY
OVERDONE...BUT VALUES SHOULD STILL TOP 2 INCHES. WARM CLOUD DEPTHS
OF 13-14K FEET SUGGEST EFFICIENT WARM RAIN PROCESSES TO WRING OUT
THE ABUNDANT MOISTURE. CORFIDI VECTORS ALSO POINT TO POTENTIAL FOR
BACKBUILDING/TRAINING STORMS AND SLOW STORM MOTIONS. THE HEAVY RAIN
THREAT WILL LIKELY BE CONFINED TO THE NORTHWEST COUNTIES THROUGH 00Z
MONDAY EVENING. AFTER A SEVERAL DAY RESPITE FROM HEAVY
RAIN...ANTECEDENT SOIL MOISTURE CONDITIONS LIKELY DO NOT FAVOR
WIDESPREAD FLASH FLOODING. HOWEVER...WE WILL HAVE TO MONITOR FOR
LOCALIZED VERY HIGH RAINFALL AMOUNTS AND RATES...ESPECIALLY IN URBAN
AREAS.

REGARDING SEVERE STORMS...THERE IS SOME POTENTIAL FOR A FEW STRONG
TO SEVERE WIND GUSTS WITH PRECIP LOADED STORMS IN A FAVORABLE LOW
LEVEL LAPSE RATE ENVIRONMENT. LACK OF SUBSTANTIAL DEEP LAYER SHEAR
MEANS THAT QUARTER SIZE OR LARGER HAIL WILL LIKELY BE VERY HARD TO
COME BY. MOST OF THE FORECAST AREA...EXCEPT FOR THE FAR EAST AND
SOUTHEAST FRINGES...IS NOW IN THE SWODY2 SLIGHT RISK AREA.

HAVE MADE SOME MINOR ADJUSTMENTS TO MONDAY AFTERNOON TEMPERATURES
WITH A BIT LARGER...NW/LOW 80S TO SE/UPPER 80S... GRADIENT DUE TO
CLOUD COVER.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 320 PM CDT SUN JUL 5 2015

THE OVERALL SIGNAL POINTS TO THE WEATHER PATTERN TURNING ACTIVE
AGAIN WITH THE FLOW ALOFT COMING FROM THE SOUTHWEST AGAIN.
HOWEVER...IT IS NOT KNOWN WITH ANY CERTAINTY IF THIS WILL BE THE
PREVAILING FLOW PATTERN.

THE COLD FRONT SWEEPS THROUGH THE AREA MONDAY NIGHT AND EXITS THE
AREA SHORTLY AFTER SUNRISE TUESDAY. THE FORCING IS MAINLY
ALONG/BEHIND THE FRONT AND PWATS ARE EXTREMELY HIGH. ALTHOUGH NOT AT
A MAXIMUM FOR JULY...THE PWATS ARE GENERALLY AROUND THE 99TH PERCENT
LEVEL WHICH WOULD SUPPORT THE POTENTIAL FOR HEAVY RAIN. THE GROUND
HAS DRIED OUT ENOUGH THAT IT SHOULD BE ABLE TO TAKE AN INCH OF
RAIN WITH NO PROBLEMS.

STORMS MONDAY NIGHT SHOULD BE EXTREMELY EFFICIENT IN PRODUCING
RAINFALL. THIS RAINFALL COULD BE EXCESSIVE IF STORMS WOULD DEVELOP
AND MOVE OVER THE SAME AREA. PRESENTLY THERE IS NO CLEAR SIGNAL
SUGGESTING THIS. ALTHOUGH SLOW...THE FRONT SHOULD NOT STALL MOVING
THROUGH THE AREA.

LINGERING RAIN OVER THE SOUTHEAST HALF TUESDAY MORNING WILL END
DURING THE MORNING LEAVING DRY CONDITIONS FOR TUESDAY AFTERNOON.

THE FRONT WILL STALL OUT ACROSS MISSOURI BY SUNSET TUESDAY. WHERE
THE FRONT STALLS WILL BE IMPORTANT REGARDING SENSIBLE WEATHER
CONDITIONS FOR TUESDAY NIGHT INTO WEDNESDAY. THE MODELS GENERALLY
AGREE THAT TUESDAY EVENING SHOULD BE DRY ACROSS THE AREA. AFTER
MIDNIGHT SEVERAL MODEL SOLUTIONS ARE DEVELOPING A THUNDERSTORM
COMPLEX IN WESTERN MISSOURI THAT MOVES EAST NORTHEAST.

GOING ON THE ASSUMPTION THAT THE FRONT WILL STALL OUT ACROSS CENTRAL
MISSOURI...THE SOUTH THIRD OF THE AREA SHOULD SEE SHOWERS AND SOME
THUNDERSTORMS DEVELOPING LATE TUESDAY NIGHT THAT OVERSPREADS THE
SOUTH HALF OF THE AREA ON WEDNESDAY.

WEDNESDAY NIGHT ON...

THE MODEL SOLUTIONS VARY CONSIDERABLY FROM WEDNESDAY NIGHT THROUGH
NEXT WEEKEND. VARIABLES IN PLAY ARE WHERE THE FRONT SETS UP...WHERE
POTENTIAL NIGHTLY THUNDERSTORM COMPLEXES DEVELOP AND MOVE...AND THE
OVERALL STRENGTH OF HIGHS DROPPING INTO THE GREAT LAKES.

RIGHT NOW THE MODEL CONSENSUS HAS SLIGHT CHANCE TO CHANCE POPS EACH
DAY FROM WEDNESDAY NIGHT THROUGH SUNDAY. IT MUST BE EMPHASIZED THAT
THERE WILL BE PERIODS OF DRY WEATHER IN THE WEDNESDAY NIGHT THROUGH
SUNDAY TIME FRAME. THESE DRY PERIODS MAY BE MANY HOURS LONG.
HOWEVER...THERE IS NO CLEAR SIGNAL TO GIVE ANY CONFIDENCE ON WHEN

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1126 PM CDT SUN JUL 5 2015

A COLD FRONT WILL APPROACH EASTERN IOWA AND NORTHWEST ILLINOIS
DURING THE DAY MONDAY...AND SHOULD PASS THROUGH THE REGION MONDAY
NIGHT. THIS WILL BRING WIDESPREAD SHOWERS AND THUNDERSTORMS TO
THE REGION...WITH SOME MVFR TO IFR POSSIBLE IN THUNDERSTORMS.
WHILE THE THREAT FOR SHOWERS AND STORMS IS A LONG DURATION FROM
MID MORNING...THROUGH ALL OF THE EVENING...IT IS UNLIKELY THAT
CONDITIONS WILL SEE CONTINUOUS RAIN AND THUNDERSTORMS. FOR THAT WE
HAVE RESOLVED TO SHOW A VICINITY SHOWER THREAT DURING THE DAY WHEN
CHANCES ARE LOWER...AND A HIGH THREAT FOR STORMS IN THE AFTERNOON
AND EVENING. WINDS WILL BE SOUTH OVERNIGHT...AND SOUTHWEST
MONDAY...AHEAD OF THE FRONT. MONDAY NIGHT...A WIND SWITCH TO WEST
AND NORTHWEST CAN BE EXPECTED AFTER MIDNIGHT. ERVIN

&&

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

$$

SYNOPSIS...RP KINNEY
SHORT TERM...RP KINNEY
LONG TERM...08
AVIATION...ERVIN


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