Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 121224
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
724 AM CDT SAT JUL 12 2014

.UPDATE...
ISSUED AT 721 AM CDT SAT JUL 12 2014

THUNDERSTORM COMPLEX CONTINUES TO WEAKEN AS IT MOVES EAST. DEBRIS
CLOUDS AND A VERY WEAK COOL POOL FROM THE STORM COMPLEX SUGGESTS A
LULL IN RAIN POTENTIAL THIS MORNING. NEW DIURNAL CONVECTION SHOULD
BEGIN DEVELOPING AROUND MID DAY AND CONTINUE THROUGH THE
AFTERNOON. THE CURRENT FORECAST HAS BEEN UPDATED TO REFLECT THESE
TRENDS.

UPDATE ISSUED AT 625 AM CDT SAT JUL 12 2014

THE THUNDERSTORM COMPLEX IS CURRENTLY MOVING THROUGH THE AREA.
STORMS ON THE EAST AND SOUTH EDGE HAVE PRODUCED SOME LOCALIZED
WIND GUSTS TO 50 MPH ALONG WITH COPIOUS RAINFALL OF AN INCH PLUS
IN LESS THAN AN HOUR.

RECENT TRENDS SHOW THIS COMPLEX WEAKENING OVER THE NEXT SEVERAL
HOURS. THE WEAK COOL POOL PRODUCED BY THESE STORMS BRINGS TO
QUESTION THE MAX TEMPERATURES ACROSS THE NORTH THIRD OF THE AREA
LATER TODAY. THE POTENTIAL DOES EXIST FOR TEMPERATURES TO REMAIN
IN THE 70S ACROSS THE NORTH THIRD DUE TO THE RAIN AND CLOUD COVER.

&&

.SYNOPSIS...
ISSUED AT 232 AM CDT SAT JUL 12 2014

06Z SFC ANALYSIS HAS A WEAK LOW IN CENTRAL NEBRASKA WITH A
STATIONARY FRONT RUNNING ROUGHLY EAST TO KDSM AND THEN SOUTHEAST TO
NEAR KSTL. THE MAIN COLD FRONT RAN FROM WESTERN LAKE SUPERIOR TO A
WEAK LOW NEAR KPIR AND THEN INTO NORTHEAST WYOMING. DEW POINTS WERE
IN THE 50S ACROSS THE GREAT LAKES WITH MAINLY 60S IN THE REMAINDER
OF THE MIDWEST AND PLAINS. DEW POINTS IN THE 70S RAN FROM THE GULF
COAST UP THROUGH WESTERN IOWA AND SOUTHWEST MINNESOTA.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 232 AM CDT SAT JUL 12 2014

THE SMALL THUNDERSTORM COMPLEX THAT DEVELOPED IN EASTERN NEBRASKA
HAS MOVE INTO THE WESTERN HALF OF IOWA AND HAS GROWN. ACROSS EASTERN
IOWA AND ILLINOIS SHOWERS AND SOME THUNDERSTORMS WERE DEVELOPING IN
RESPONSE TO INCREASED FORCING FROM AN APPROACHING DISTURBANCE ALOFT.

WHAT IS SUGGESTED BY RECENT DATA AND THE MODELS IS THAT THE
THUNDERSTORM COMPLEX WILL CONTINUE TO SLOWLY MOVE EAST SOUTHEAST
THROUGH SUNRISE AND INTO THE AREA DURING THE MORNING FOLLOWED BY A
SLOW DISSIPATION. CONVECTION AHEAD OF THE COMPLEX SHOULD CONTINUE TO
DEVELOP AND EVENTUALLY MERGE WITH THE APPROACHING THUNDERSTORM
COMPLEX.

PRECIPITATION AND CLOUD COVER MAY SUPPRESS TEMPERATURES ACROSS THE
NORTHERN THIRD OF THE AREA FOR MUCH OF THE DAY. THE POTENTIAL FOR A
QUICK JUMP IN TEMPERATURES IS THERE LATE IN THE DAY IF PARTIAL
CLEARING CAN OCCUR.

BOUNDARIES FROM THIS COMPLEX COMBINED WITH DAY TIME HEATING WILL
PROVIDE THE FOCUS FOR NEW STORM DEVELOPMENT DURING THE AFTERNOON AND
EVENING AHEAD OF THE MAIN COLD FRONT. SOME OF THESE STORMS MAY
BE SEVERE.

STORMS WILL PERSIST THROUGH THE EVENING AND OVERNIGHT HOURS BUT
AREAL COVERAGE AND INTENSITY SHOULD SLOWLY DECREASE AFTER MIDNIGHT
AS THE COLD FRONT MOVES THROUGH THE AREA.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 232 AM CDT SAT JUL 12 2014

SEASONABLY WELL BELOW NORMAL FOR MID JULY THE MAIN THEME STARTING ON
SUNDAY.

OVERVIEW...INITIALIZATION AND VERIFICATION AT 06Z IS EXCELLENT WITH
TRENDS CONTINUE OF A STRONG AND POSSIBLY RECORD COLD AIR MASS ARRIVING
LATE SUNDAY INTO MIDDLE OF NEXT WEEK. RUN TO RUN VARIANCE SUPPORTS
ONLY MINOR VARIANCES WITH A 70/30 BLEND OF GFS WITH ECMWF/GEM-NH
SUGGESTED. ONLY SENSIBLE WEATHER ISSUES ARE RISK OF ISOLATED PM
SHOWERS AFTER SUNDAY AND HOW COOL MINS WILL BE EARLY NEXT WEEK.
THIS COOL FRONT SHOULD BE ONE OF THE STRONGEST AND COOLEST COOL
FRONTS SEEN IN MANY YEARS FOR MID JULY. THE MAGNITUDE OF THIS COOL
SPELL WILL BE BETTER ASSESSED IN THE NEXT COUPLE OF DAYS.

SUNDAY...LAST NEAR NORMAL MID JULY DAY WITH INCREASING NORTHERLY WINDS
AND SOME ISOLATED STORMS IN SOUTH AS FRONT MOVES SOUTH AS DEWPOINTS
FALL INTO THE LOWER 60S AND POSSIBLY UPPER 50S NORTH BY EVENING.
MAX TEMPERATURES SHOULD RANGE 80 TO 85 DEGREES. OVERALL A COMFORTABLY
WARM MID SUMMER DAY. SUNDAY NIGHT...POSSIBLY SOME ISOLATED STORMS
AND SHOWERS INTO THE MID EVENING HOURS...THEN CLEARING AND COOLER
WITH LOWS UPPER 50S NORTH TO LOWER 60S SOUTH WITH SOME BL DECOUPLING
THAT MAY ALLOW FOR MINS A FEW DEGREES LOWER FOR LATER SHIFTS.

MONDAY...STRONG UPPER LOW TO MOVE INTO AREA BY AFTERNOON WITH INCREASING
NORTH TO NORTHWEST WINDS OF 10 TO 20 MPH AND OCCASIONAL 25 MPH GUSTS.
LOW POPS NEEDED...MAINLY FOR PM SHOWERS AND ISOLATED STORM SOUTH AS
COLD AIR ALOFT ALLOWS FOR SOME DESTABILIZATION OF WEAK POPCORN SHOWERS
AND ISOLATED STORM IN THE SOUTH. HAVE LOWERED MAX TEMPS MOST LOCATIONS
AS WAS DISCUSSED MAY BE NEEDED YESTERDAY WITH NORTH SECTIONS STAYING
IN THE LOWER 70S...TO UPPER 70S SOUTH SECTIONS. MONDAY NIGHT MINS WITH
850 TEMPS OF +5 TO +9C SUGGEST SOME MID TO UPPER 40S PROBABLE FOR
LATER SHIFTS THAT MAY THREATEN RECORDS.

TUESDAY AND WEDNESDAY...REMARKABLY COOL WITH HIGHS 67 TO 73 DEGREES
ON TUESDAY AND ABOUT 2-3 DEGREES WARMER ON WEDNESDAY...OR 70 TO 76
FOR LATER SHIFTS TO REASSESS. THIS WOULD BE WELL OVER 10 DEGREES BELOW
NORMAL. WEDNESDAY MORNING LOWS SUPPORT NEED TO TRIM FURTHER BY 3-5
DEGREES IF WINDS DECOUPLE...BECOMING CALM FOR SEVERAL HOURS AND IS
SUGGESTED WHICH SHOULD BREAK RECORD COOL MINS.

THURSDAY AND FRIDAY...SLOW WARM-UP AS LARGE CANADIAN HIGH PRESSURE
MOVES EAST AND MODIFIES WITH HIGHS STILL VERY COMFORTABLE WITH
UPPER 70S TO AROUND 80 DEGREES AND LOWS STILL MOSTLY IN THE MID TO
UPPER 50S MOST LOCATIONS. POSSIBLE PM SHOWER OR STORM MAY BE NEEDED
BY LATER SHIFTS AND DEWPOINTS SLOWLY RISE AND INTERACT WITH WEAK
UPPER DISTURBANCES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 625 AM CDT SAT JUL 12 2014

A WEAKENING THUNDERSTORM COMPLEX MOVING ACROSS EASTERN IOWA INTO
ILLINOIS WILL PRODUCE BRIEF IFR CONDITIONS AS THEY AFFECT A TAF
SITE. ONCE THE STORM COMPLEX HAS CLEARED THE AREA A PERIOD OF MVFR
CONDITIONS WILL BE POSSIBLE. NEW STORMS ARE EXPECTED TO DEVELOP
AFT 18Z/12 AND CONTINUE THROUGH SUNRISE SUNDAY AS A STRONG COLD
FRONT MOVES THROUGH THE AREA. THESE STORMS WILL HAVE THE POTENTIAL
TO PRODUCE MVFR/IFR CONDITIONS.


&&

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

$$

UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...NICHOLS
AVIATION...08






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