Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 150907 CCA
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
407 AM CDT WED APR 15 2015

.SYNOPSIS...
ISSUED AT 239 AM CDT WED APR 15 2015

ANALYSIS AT 2 AM CDT SHOWS CONSIDERABLE HIGH OVER ALL BUT FAR NE
SECTIONS OF THE AREA. THIS IS KEEPING TEMPERATURES IN THE MID 40S
TO LOWER 50S FAR SW WITH FAR NE SECTIONS AROUND 40F. ANALYSIS
SHOWS WEAK FLOW WITH WEAK DISTURBANCE IN MISSOURI SLOWLY WASHING
OUT OR FILLING. UPPER LOW IN UTAH ANALYSIS SUPPORTS PROGS OF
SYSTEM TO STALL FOR AT LEAST NEXT FEW DAYS WITH MOSTLY DRY TO DRY
CONDITIONS BUT CLOSE ENOUGH FOR PERIODS OF CLOUDS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 239 AM CDT WED APR 15 2015

SHORT TERM FORECAST CONFIDENCE ASSESSMENT...GOOD OR ABOVE AVERAGE.
LITTLE CHANGE IN PATTERN NEXT 24 HOURS SUGGESTING USE OF
PERSISTENCE. CLOUDS BIGGEST ISSUE WITH CONSIDERABLE MID AND MOSTLY
HIGH CLOUDS NEXT 24 HOURS RESULTING PARTLY TO MOSTLY CLOUDY SKIES.

TODAY...HIGHS UNLESS CLOUDS ARE THICKER SUGGEST NEAR WARMEST END OF
GUIDANCE. TRENDS SUGGEST PARTLY CLOUDY NORTH WITH MOSTLY CLOUDY SOUTH
SECTIONS. THIS MEANS UPPER 60S TO AROUND 70 DEGREES NEAR I-80
CORRIDOR. EAST WINDS TODAY OF 10 TO 15 PLUS MPH AND SOME GUSTS NEAR
20 MPH POSSIBLE NORTH OF I-80. OVERALL ANOTHER COOL BUT COMFORTABLE
DAY. RADAR TRENDS OF DECAYING FORCING FROM MISSOURI DO SUGGEST SOME
SPRINKLES POSSIBLE FAR SOUTH SECTIONS TODAY INTO EARLY AFTERNOON
HOURS.

TONIGHT...LOWS WITH PARTLY CLOUDY SKIES SIMILAR TO PREVIOUS NIGHT
WITH LOWER 40S FAR NORTH AND NE AND UPPER 40S TO NEAR 50F FAR SW AND
SOUTH SECTIONS DUE TO MAINLY MORE CLOUDS THERE. DECAYING FORCING
SUGGEST LOCATIONS SOUTH OF HIGHWAY 34 COULD SEE ISOLATED SPRINKLES
OR SLIGHT CHANCE OF LIGHT RAIN...MAINLY BEFORE MIDNIGHT.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 407 AM CDT WED APR 15 2015

OVERVIEW...A VIGOROUS SHORTWAVE TROUGH HAS MOVED INTO THE WESTERN
U.S. AND WILL TRANSITION INTO A CUT-OFF 500MB LOW OVER THE FOUR
CORNERS REGION THROUGH TODAY. THE LOW WILL SLOWLY PROPAGATE EASTWARD
AND WEAKEN THROUGH TIME. AT LEAST A VESTIGE OF THE SYSTEM WILL REACH
THE SOUTHERN MIDWEST BY SUNDAY.

THURSDAY...MODEL TRENDS SUPPORT THE REMOVAL OF POPS FROM THE
FORECAST. SHOULD BE A VERY NICE DAY WITH HIGHS IN THE LOWER 70S AND
LIGHT WINDS. 500MB HEIGHT RISES WILL ACTUALLY OCCUR THROUGH THE DAY
IN ADVANCE OF THE DIGGING CUT-OFF LOW OVER THE FOUR CORNERS.

FRIDAY...MID-LEVEL FLOW BECOMES ZONAL AND 1000-500MB THICKNESSES
WILL AVG NEAR 558 DAM AND STEADY WSW WINDS WILL DEVELOP. EXPECT WARM
TEMPS INTO THE LOW TO MID 70S WHICH IS ABOUT 10 DEGREES ABOVE AVG.
WENT WITH A SLIGHT CHANCE FOR SHOWERS...20 PERCENT. IF ANYTHING DOES
FORM IT SHOULD REMAIN ISOLATED.

THE 00Z/4.15 NAM WAS AN OUTLIER BRINGING SCT SHOWERS/TSTORMS ACROSS
MUCH OF THE CWA ON FRI. FEEL NAM IS TOO HIGH WITH SFC DEWPOINTS IN
THE UPPER 50S/LOWER 60S AND PWAT VALUES GREATER THAN 1 INCH.

SATURDAY AND SUNDAY...MODELS IN GENERAL AGREEMENT ON DROPPING AN
ALBERTA CLIPPER DOWN TO N MINNESOTA BY SUN AND PULLING THE CUT-OFF
LOW NORTHEASTWARD TOWARD WESTERN GREAT LAKES. BUT THEY DIFFER ON
TIMING. AT THE SFC...THE MODELS FORM AN ELONGATED TROUGH/DUAL-LOW
STRUCTURE WHICH STRETCHES FROM SOUTHERN MANITOBA ALL THE WAY DOWN TO
ARKANSAS.

ENSEMBLE ANALYSIS...THE 00Z/4.15 ECMWF DETERMINISTIC SOLUTION WAS IN
GOOD SPATIAL/STRUCTURAL AGREEMENT AT 500MB COMPARED TO THE ECMWF
ENSEMBLE MEAN...AT THE 108 HR FORECAST HR OR 12Z/SUN. THE SPREAD
AMONG THE ENSEMBLE MEMBERS IS NEAR THE AVG SPREAD AT THIS LEAD OVER
THE PAST MONTH...SO I HAVE CONFIDENCE SIDING MORE WITH THE ECMWF ON
TIMING. THE ECMWF IS MAINLY A SUNDAY RAIN EVENT WHILE THE GFS BRINGS
THE PRECIP IN 12-18 HOURS EARLIER.

RAIN POTENTIAL...FOR NOW HAVE 40-50 POPS SUN/SUN NIGHT. AT THIS
POINT IT DOES NOT LOOK LIKE A HEAVY RAIN EVENT. ONE SFC LOW IS
FORECAST TO TRACK ACROSS MANITOBA AND ANOTHER ACROSS E ILLINOIS
WHICH MEANS BEST SYNOPTIC FORCING MISSES THE DVN CWA. HOWEVER...A
SHIFT IN TRACK OF THE EASTERN LOW COULD RESULT IN HIGHER RAINFALL
TOTALS FOR OUR AREA...SOMETHING TO MONITOR THROUGH THE WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1124 PM CDT TUE APR 14 2015

OVERCAST HIGH CLOUDS WILL CONTINUE...ALONG WITH EAST WINDS BETWEEN
5 AND 10 KTS THROUGH THE NEXT 24 HOURS. LOW PRESSURE WILL APPROACH
FROM THE SOUTH WEDNESDAY...BUT WITH VERY DRY AIR IN PLACE OVER
IOWA AND ILLINOIS...THIS SHOULD MAINLY PRODUCE MID AND HIGH CLOUDS
ABOVE 12000 FT.
ERVIN


&&

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

&&

$$

SYNOPSIS...NICHOLS
SHORT TERM...NICHOLS
LONG TERM...UTTECH
AVIATION...ERVIN










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