Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 200837 CCA
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
336 AM CDT SAT SEP 20 2014

.SYNOPSIS...
ISSUED AT 330 AM CDT SAT SEP 20 2014

DOPPER RADAR INDICATED A LINE OF THUNDERSTORMS FROM GREEN BAY
WISCONSIN TO EAST OF GUTTENBERG IOWA ASSOCIATED WITH UPPER LEVEL
JET ENERGY AND WERE MOVING EAST. OVER THE PAST SEVERAL HOURS THE
LINE HAS RAPIDLY WEAKENED AS IT APPROACHED THE DVN CWA BUT STORMS
ARE STRONGER IN WESTERN IA WHERE THE BETTER SHEAR/SBCAPE IS
LOCATED. AT 3 AM TEMPERATURES IN THE CWA WERE IN THE LOWER TO MID
60S WITH DEWPOINTS IN THE MID 50S TO LOWER 60S. IN WESTERN IA THE
DEWPOINTS WERE AROUND 70 WITH PWAT`S OF 1.7 INCHES. A COLD FRONT
EXTENDED FROM THE MN ARROWHEAD TO NORTHERN NEBRASKA AND
TEMPERATURES WERE IN THE 50S BEHIND THE FRONT.

IR SATELLITE LOOPS SHOWED DEBRIS CLOUDS FROM THE THUNDERSTORMS
WERE SPREADINGS ACROSS MUCH OF THE DVN CWA.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT SAT SEP 20 2014

FORECAST FOCUS ON THUNDERSTORM CHANCES TODAY.

TODAY...FORCING CONTINUES TO WEAKEN AS LOW LEVEL WINDS VEER
WESTERLY AHEAD OF THE APPROACHING COLD FRONT. THIS WILL KEEP SHOWERS
AND THUNDERSTORMS SCATTERED IN COVERAGE. MOST OF THE OPERATIONAL
MODELS SEEM WAY OVERDONE INDICATING WIDESPREAD QPF DUE TO THEIR
DEWPOINTS AND CAPE VALUES TOO HIGH. LOTS OF CLOUD COVER EXPECTED
THIS MORNING WHICH WILL IMPACT MAXIMUM TEMPERATURES. IN ADDITION...
THE COLD FRONT WILL BE PUSHING INTO EASTERN IA LATER THIS MORNING
AND INTO WESTERN IL THIS AFTERNOON. THIS SHOULD KEEP THE SEVERE
THREAT LOW. WITH THIS IN MIND I HAVE LOWERED MAXIMUM TEMPERATURES
A BIT...KEEPING READINGS IN THE UPPER 70S TO LOWER 80S.

TONIGHT...WILL HAVE SMALL POPS IN THE FAR NORTH AS A STRONG VORT
MAX SWINGS ACROSS THE UPPER MIDWEST BUT THE BULK OF THE QPF WITH
THIS FEATURE SHOULD REMAIN IN MN AND WI. NORTHWEST WINDS WILL
USHER COOLER AND DRIER AIR INTO THE CWA. MINIMUM TEMPERATURES WILL
BOTTOM OUT IN THE LOWER 50S NW TO THE UPPER 50S SE.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 330 AM CDT SAT SEP 20 2014

BASICALLY DRY CONDITIONS WITH BELOW NORMAL TEMPERATURES THROUGH
MONDAY...WARMING TO SLIGHTLY ABOVE NORMAL THURSDAY INTO FRIDAY.

LONG TERM FORECAST CONFIDENCE ASSESSMENT...ABOVE AVERAGE OR GOOD
WITH LITTLE SENSIBLE WEATHER ISSUES AS GENERALLY DRY CONDITIONS
PREVAIL. TEMPERATURES DAYS 2-7 SHOULD BE WITHIN 3 DEGREES OF
FORECAST.

OVERVIEW...INITIALIZATION AND VERIFICATION AVERAGE WITH NORMAL
ISSUES WITH PRECIPITATION ALONG FRONTAL PASSAGE TODAY.  VERY MINOR
SENSIBLE WEATHER SUNDAY ISSUES ALL SOLUTIONS DAYS 2-7.  VERIFICATION
AND RUN TO RUN ANALYSIS SUPPORTS A 60/40 MIX OF HI-RES ECMWF/GFS.
VERIFICATION CONTINUES TO SUGGEST DIURNAL TEMPERATURE RANGES A BIT
UNDERDONE MOST DAYS WITH HIGHS...ESPECIALLY TUESDAY ONWARD A DEGREE
OR TWO HIGHER AND LOWS AT LEAST A DEGREE OR TWO LOWER SUNDAY NIGHT
THROUGH FRIDAY MORNING.

SUNDAY AND SUNDAY NIGHT...PASSING SHORT WAVE DIVING SE FROM MANITOBA
A BIT STRONGER WITH LOW POPS OF LIGHT SHOWERS OR MORE LIKELY JUST
SPRINKLES ADDED N/E 1/4 OF FORECAST AREA INTO EARLY AFTERNOON WITH
MORE CLOUDS THERE. STRONGER CAA TO ALLOW FOR MORE VIGOROUS BL MIXING
WITH HIGHER NW WINDS OF 15 TO 25+ MPH AND OCCASIONAL GUSTS NEAR 30
MPH MID DAY NORTH OF HIGHWAY 34. HIGHS WITH COOLER LOW LEVEL THERMAL
FIELDS SUGGEST UPPER 60S NE TO LOWER 70S SE SECTIONS. SUNDAY NIGHT...
LOWERED LOWS 1-2 DEGREES AND SEASONABLY COOL WITH LOWS MOSTLY 44 TO
49 DEGREES WITH FAVORED LOW LYING LOCATIONS NORTH SECTIONS LIKELY A
DEGREE OR TWO TOO MILD FOR LATER SHIFTS TO CONSIDER IF BL WINDS
DECOUPLE AND BECOME LIGHT TO CALM.

MONDAY THROUGH FRIDAY...QUIET EARLY FALL WEATHER WITH FAIR SKIES UNDER
LARGE HIGH PRESSURE SYSTEM AND LIGHT WINDS.  HIGHS SHOULD BE MOSTLY
70-75 THROUGH WEDNESDAY...THEN 75-80 THURSDAY AND FRIDAY AS SOUTH
WINDS DEVELOP. MINS UPPER 40S TUESDAY RISING INTO THE MIDDLE 50S BY
THURSDAY AND FRIDAY MORNING. LIGHT SE WINDS DO SUGGEST LOWS WILL NEED
LOWERING A DEGREE OR TWO MOST AREAS BY LATER SHIFTS. LOW POPS OF
DECAYING LIGHT SHOWERS WEDNESDAY AND THURSDAY FROM WEAK UPPER TROUGH
MAY BE ABLE TO BE PULLED AS LOW MOISTURE AND UPPER HIGH FOR
SUBSIDENCE SHOULD MAKE THESE PRECIPITATION CHANCES UNFAVORABLE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 330 AM CDT SAT SEP 20 2014

VFR WEATHER AND SOUTHERLY WINDS WILL CONTINUE OVERNIGHT...AS A
COLD FRONT APPROACHES THE REGION FROM MINNESOTA. A LARGE LINE OF
STORMS IS CURRENTLY ALONG THIS FRONT FROM SOUTHEAST MINNESOTA TO
NORTHEAST NEBRASKA. THESE STORMS SHOULD GRADUALLY FALL APART AS
THEY MOVE EAST OVERNIGHT. THE FRONT WILL BRING A THREAT FOR
SCATTERED SHOWERS AND THUNDERSTORMS TO EASTERN IOWA AFTER 09Z/20.
THIS ACTIVITY IS HANDLED WITH A VICINITY WORDING IN THE TAFS DUE
TO THE LOW COVERAGE OF ACTIVITY. THE COLD FRONT SHOULD BE EAST OF
IOWA AND NORTHWEST ILLINOIS BY SATURDAY AFTERNOON...WITH WINDS
BECOMING WEST AT 10 TO 20 KTS AT THAT TIME. VFR CONDITIONS WILL
PERSIST THROUGH THE ENTIRE PERIOD...BUT COULD DROP TO MVFR IF AN
ISOLATED SHOWER OR STORM WERE TO IMPACT A TERMINAL DIRECTLY
SATURDAY MORNING.

&&

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

$$

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









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