Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 150441
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1141 PM CDT SUN SEP 14 2014

.UPDATE...
ISSUED AT 1141 PM CDT SUN SEP 14 2014

HAVE UPDATED THE OVERNIGHT FORECAST TO DELAY THE ONSET OF RAIN AND
ISOLATED THUNDERSTORMS TO CLOSER TO MORNING. LARGELY DRY
SOUNDINGS AT 00Z...BOTH AT KDVN AND UPSTREAM AT KOMA WILL TAKE SOME
TIME TO SATURATE ONCE THE UPPER LEVEL FORCING IN THE PLAINS MOVES
IN LATER TONIGHT. LATEST RADAR IMAGES SHOW BANDED...VERY HIGH
BASED LIGHT RAIN SHOWERS FROM SE SD ACROSS SOUTHERN MN INTO
SOUTHERN WI ASSOCIATED WITH A 100KT PLUS JET STREAK ANALYZED AT
00Z FROM SE ND EAST THROUGH NORTHERN LOWER MI. THIS...BAND ALONG
WITH A SEPARATE A WEAK SHORTWAVE OVER KS AND NEB...AND THE PRIMARY
SHORTWAVE MOVING INTO THE WESTERN DAKOTAS WILL LEAD TO WIDESPREAD
LIGHT RAIN SHOWERS...NOT LIKELY TO DEVELOP EAST OF THE MS RIVER
UNTIL AFTER SUNRISE. WILL LEAVE IN A MENTION OF AT LEAST ISOLATED
THUNDERSTORMS ACROSS THE SOUTH...AS A LONE CELL OVER NW MO HAD
ALREADY GENERATED SOME LIGHTNING WITHIN THE PAST HOUR. THIS WAS ALONG
A MID LEVEL THETAE LAPSE RATE GRADIENT...WHICH IS PROGGED TO
TRANSITION EASTWARD OVERNIGHT.

&&

.SYNOPSIS...
ISSUED AT 306 PM CDT SUN SEP 14 2014

ANALYSIS AT 2 PM SHOWS DEVELOPING SHORT WAVE IN THE CENTRAL PLAINS
AS DIGGING VORT MAX FROM CANADA DIVES SOUTH. PRESSURE AND HEIGHT
FALLS WITH INCREASING CLOUDS AND ACCAS ALL SUPPORTING AREAS OF SHOWERS
AND ISOLATED STORMS TO DEVELOP THERE IN THE NEXT 2-4 HOURS. UPSTREAM
ENERGY SUPPORTS A FAST MOVING SYSTEM WITH MORE NICE EARLY FALL WEATHER
THEN IN NW FLOW FOR THE NEXT SEVERAL DAYS AFTER MONDAY WITH SLIGHTLY
BELOW NORMAL TO BELOW NORMAL TEMPERATURES.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 306 PM CDT SUN SEP 14 2014

SHORT TERM FORECAST CONFIDENCE ASSESSMENT...AVERAGE TO ABOVE AVERAGE
OR FAIR TO GOOD. MAIN ISSUES ARE TIMING ARRIVAL OF AREAS OF RAIN AND
ISOLATED STORMS LATE TONIGHT BETWEEN 12 AM AND 3 AM AND EXITING BY
MID AFTERNOON WITH RAIN TOTALS AND LOCATIONS OF HEAVIEST RAIN WITH
ANY ISOLATED STORMS THAT APPEAR A MARGINAL RISK. INITIALIZATION AND
VERIFICATION SUGGESTS SURFACE DEWPOINTS ARE A FEW DEGREES TOO HIGH
SUGGESTING SLIGHTLY DELAYED ARRIVAL OF RAIN AND RAIN AMOUNTS.

TONIGHT...CLOUDS TO INCREASE THIS EVENING WITH MOST LOWS AT OR
BEFORE MIDNIGHT BEFORE SLOWLY RISING AS CLOUDS AND PRECIPITATION
ARRIVES OVERNIGHT AND THEN BECOMES WIDESPREAD AROUND DAWN AS SURFACE
FRONT MOVES INTO AREA. BEST CHANCE OF ISOLATED...NON-SEVERE CONVECTION
SHOULD BE...IF OCCURS AT ALL...ALONG AND SOUTH OF HIGHWAY 34 BETWEEN
3 AM AND 7 AM.

MONDAY...CLOUDY WITH AREAS OF LIGHT RAIN AND SHOWERS...MOSTLY ALONG
AND JUST BEHIND FRONTAL PASSAGE. EVAPORATIVE COOLING AND CLOUDS SUPPORTS
HIGHS BELOW MOST GUIDANCE WITH UPPER 50S TO AROUND 60 DEGREES WITH
CLEARING LATE THAN MAY ALLOW NW SECTIONS TO BE A FEW DEGREES HIGHER.
OVERALL RAIN AMOUNTS SHOULD BE LIGHT...MOSTLY IN THE .1 TO LOCALLY
NEAR .3 OF AN INCH WITH FORCING TOOLS SUGGESTING THE HIGHEST AMOUNTS
ROUGHLY ALONG HIGHWAY 34 CORRIDOR IN IOWA INTO EXTREME WEST CENTRAL
ILLINOIS TO POTENTIALLY ALONG THE I-80 CORRIDOR. ISOLATED BRIEF NON-
SEVERE STORM MAY STILL OCCUR ALONG AND SOUTH OF HIGHWAY 34 CORRIDOR
UNTIL MID MORNING BASED ON MID LEVEL LAPSE RATES AND FORCING FROM
THE LIFT TOOL.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 306 PM CDT SUN SEP 14 2014

.LONG TERM...MONDAY NIGHT THROUGH NEXT SUNDAY...
FORECAST FOCUS...DRY AND PLEASANT MUCH OF THIS WEEK THEN A CHANCE OF
THUNDERSTORMS TOWARDS THE WEEKEND. TEMPERATURES START THE WEEK BELOW
NORMAL BUT THEN BY THE WEEKEND END UP A BIT ABOVE NORMAL.

MONDAY NIGHT THROUGH THURSDAY NIGHT...DRY NORTHWEST FLOW ALOFT WITH
HIGH PRESSURE AT THE SURFACE. HEIGHTS GRADUALLY RISE DURING THE WEEK
SO TEMPERATURES WILL SHOW A GRADUAL MODERATION. MAXIMUM TEMPERATURES
EARLY IN THE WEEK WILL BE IN THE 60S WARMING INTO THE 70S TOWARDS
THE END OF THE WORK WEEK. LOWS WILL BE IN THE 40S WARMING INTO THE
50S AS THE WEEK PROGRESSES.

FRIDAY THROUGH SUNDAY...ECMWF SUGGESTS A MCS FORMING LATE THURSDAY
NIGHT IN WESTERN IA WITH STRONG WARM AIR ADVECTION NOTED. THIS MCS
SHOULD THEN PROGRESS INTO EASTERN IA FRIDAY MORNING GRADUALLY
LIFTING TO THE NORTHEAST AS THE NOSE OF THE LOW LEVEL JET SHIFTS
NORTHWARD. AN UPPER LEVEL TROUGH AND ASSOCIATED WEAK COLD FRONT WILL
PUSH ACROSS THE CWA SATURDAY INTO SATURDAY NIGHT...ACCOMPANIED BY
SHOWERS AND THUNDERSTORMS. THE FRONT DOESN/T APPEAR TO BE AS
STRONG AS EARLIER MODEL RUNS. THE FRONT SHOULD BE PROGRESSIVE
ENOUGH TO ALLOW FOR A DRY SUNDAY. MAXIMUM TEMPERATURES DURING THIS
TIME FRAME WILL BE ABOUT NORMAL TO A BIT ABOVE NORMAL...WITH HIGHS
IN THE 70S AND LOWS PUSHING INTO THE LOWER 60S AT SOME LOCATIONS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1141 PM CDT SUN SEP 14 2014

A WEAK WEATHER SYSTEM THAT WILL BRING LOWERING CIGS AND SCATTERED
SHOWERS INTO THE REGION IS EXPECTED TO MOVE INTO THE AREA A BIT
SLOWER THAN THE PREVIOUS FORECAST. AS A RESULT...THE ONSET OF RAIN
AND MVFR CONDITIONS HAS BEEN DELAYED A COUPLE HOURS IN THE LATEST
FORECASTS. THERE REMAINS A LOW POTENTIAL FOR AT LEAST ISOLATED
THUNDERSTORMS IN THE BRL AREA...BUT CONFIDENCE REMAINS TOO LOW TO
INCLUDE IN THE FORECASTS AT THIS TIME. THIS SYSTEM IS STILL
EXPECTED TO EXIT THE AREA BY MID TO LATE AFTERNOON WITH LIFTING
CIGS...AND EVENTUALLY CLEARING SKIES BY MONDAY EVENING. LIGHT AND
VARIABLE WINDS WILL BECOME NORTHWEST TO NORTH FOLLOWING THE
PASSAGE OF A WEAK SURFACE FRONT MONDAY MORNING.

&&

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

$$

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





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