Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 271746
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1246 PM CDT MON JUL 27 2015

.UPDATE...
ISSUED AT 1245 PM CDT MON JUL 27 2015

COMPLEX OF THUNDERSTORMS HAS FORMED OVER CENTRAL IOWA IN THE
VICINITY OF A SFC CONVERGENCE ZONE WHICH HAS OVERSHOOTING TOPS AS
COLD AS -72 C. WINDS SOUTH OF THE BOUNDARY ARE OUT OF THE SSE...TO
THE NORTH THEY ARE ESE. SPC MESOANALYSIS DEPICTED A MID-LEVEL
VORTICITY MAX PROVIDING ASCENT OVER CENTRAL IOWA. MOST MODELS DID
NOT INITIALIZE THE CONVECTIVE COMPLEX THIS MORNING...HOWEVER THE
HRRR/HRRRX HAVE FINALLY CAUGHT ONTO IT.

THE CURRENT SBCAPE GRADIENT...STORM MOTION VECTORS...AND RECENT
PROJECTS BY THE CONVECTIVE ALLOWING MODELS...ALL FAVOR A
SOUTHEASTWARD TRACK OF THE COMPLEX TOWARD MY SOUTHWEST CWA DURING
THE MID TO LATE AFTN. FOR NOW...HAVE INCREASED POPS INTO THE 20-30
PERCENT RANGE. IF ANY STRONG WINDS WERE TO OCCUR WITH THE MCS...THEY
WOULD BE LOCALIZED AND WOULD BE MOST PROBABLE OVER THE FAR
SOUTHWEST FORECAST AREA WHERE MUCAPE VALUES ARE 3000 J/KG OR
HIGHER.

&&

.SYNOPSIS...
ISSUED AT 238 AM CDT MON JUL 27 2015

AT 2 AM CDT...FORECAST AREA UNDER WEAK EASTERLY FLOW FROM YESTERDAYS/S
COOL FRONTAL PASSAGE. VERIFICATION INDICATES SLIGHTLY COOLER TREND
WITH FLOW OFF LAKE MICHIGAN AIDING IN SLIGHTLY MORE COMFORTABLE CONDITIONS.
UPSTREAM LOTS OF CLOUDS FROM PLAINS CONVECTION WHICH IS POORLY HANDLED
BY MOST SOLUTIONS. TRAJECTORIES UPSTREAM SUGGESTS WARM TO HOT AND HUMID
CONDITIONS THE NEXT COUPLE OF DAYS AND ISOLATED TO SCATTERED STORMS
POSSIBLE UNTIL NEXT FRONTAL PASSAGE ON WEDNESDAY.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 238 AM CDT MON JUL 27 2015

SHORT TERM FORECAST CONFIDENCE ASSESSMENT...FAIR TO GOOD OR AVERAGE
TO ABOVE AVERAGE. HIGHEST CONFIDENCE SW SECTIONS WITH NE SECTIONS
POSSIBLY A FEW DEGREES STILL TOO HIGH ON TEMPS AND DEWPOINTS WITH
EASTERLY FLOW OFF LAKE MICHIGAN.

TODAY...PARTLY TO MOSTLY SUNNY AND WARM TO VERY WARM AND HUMID IN
AT LEAST SW 1/2 OF AREA. LOWERED HIGHS SW BY A DEGREE AND NE SECTIONS
BY A COUPLE OF DEGREES DUE TO SLIGHTLY STRONGER AND COOLER FLOW OFF
LAKE MICHIGAN. HEAT INDICES IN FAR SW COUNTIES WILL APPROACH OR POSSIBLY
REACH HEAT ADVISORY CRITERIA OF 100F FOR A FEW HOURS BUT COVERAGE
NOT EXTENSIVE OR TEMPORALLY TO ISSUE ADVISORY ATTM. THIS ISSUE WILL
NEED TO BE MONITORED BY THE DAY SHIFT. TRENDS SUGGEST ANY ISOLATED
SHOWER OR STORM ACTIVITY IN THE SOUTH MAY BE ABLE TO BE PULLED DUE
TO LITTLE OR NO FORCING. HIGHS PROGGED TO BE MOSTLY 85 TO 90 DEGREES
NE TO SW.

TONIGHT...ONCE AGAIN PARTLY TO MOSTLY CLEAR AND HAVE TRIMMED MINS MOST
LOCATIONS 1 TO 2 DEGREES WITH STRONGER ESE FLOW AND DEWPOINTS A DEGREE
OR TWO LOWER. LIMITED FORCING AGAIN SUPPORTS KEEPING NO POPS ATTM. MINS
66 FAR NE TO AROUND 74 DEGREES FAR SW SECTIONS.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 238 AM CDT MON JUL 27 2015

FORECAST FOCUS ON HOT AND HUMID CONDITIONS TUESDAY THEN THE
POTENTIAL FOR SEVERE WEATHER AHEAD OF A COLD FRONT.

TUESDAY...UPPER LEVEL RIDGE AND STRONG CAP WILL BE OVER THE CWA
WHICH WILL SUPPRESS CONVECTION MOST OF THE DAY. THIS WILL ALLOW A
THERMAL AXIS TO SHIFT OVER THE CWA WITH 850 MB TEMPERATURES RISING
TO 20 TO 22C WHICH SHOULD SUPPORT MAXIMUM TEMPERATURES IN THE UPPER
80S TO MID 90S. DEWPOINTS ARE EXPECTED TO PUSH INTO THE OPPRESSIVE
MID TO UPPER 70S...POSSIBLY HIGHER. THIS WILL ALLOW FOR HEAT INDEX
VALUES ABOVE 100 DEGREES OVER MOST OF THE CWA. DEPENDING ON THE
EXACT TEMPERATURE AND DEWPOINT SOME LOCATIONS MAY SEE HEAT INDEX
VALUES APPROACH 110. LATER SHIFTS MAY NEED TO CONSIDER HEADLINES.

LATER IN THE AFTERNOON ON TUESDAY AND INTO TUESDAY NIGHT...LARGE
SCALE ASCENT/COOLER AIR ALOFT BEGINS TO ARRIVE...AS AN UNSEASONABLY
STRONG UPPER LEVEL TROUGH/CLOSED UPPER LOW ADVANCES ACROSS THE UPPER
MIDWEST. THIS SHOULD EFFECTIVELY BREAK THE CAP AND WITH SBCAPES OF
4000-5000 J/KG AND INCREASINGLY DEEP LAYER SHEAR THIS SHOULD SPARK
ORGANIZED CONVECTION...POSSIBLY SEVERE WITH DAMAGING WINDS AND LARGE
HAIL. SPC HAS MOST OF THE CWA IN A SLIGHT RISK FOR LATE TUESDAY
AFTERNOON AND TUESDAY NIGHT. WITH PWAT`S OVER 2 INCHES THESE STORMS
WILL ALSO HAVE TORRENTIAL RAIN AND LOCALIZED FLASH FLOODING MAY
OCCUR. THE COLD FRONT SHOULD PUSH THROUGH THE CWA BY EARLY WEDNESDAY
ENDING THE CONVECTION.

WEDNESDAY THROUGH FRIDAY...WNW FLOW ALOFT SHOULD BRING DRY WEATHER
ALONG WITH TOLERABLE LATE JULY CONDITIONS. HIGHS WILL BE IN THE
LOWER TO MID 80S WITH LOWS IN THE LOWER TO MID 60S.

THIS WEEKEND...ANOTHER COLD FRONT ARRIVES BRINGING MORE CHANCES OF
THUNDERSTORMS...ESPECIALLY ON SUNDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1245 PM CDT MON JUL 27 2015

MAINLY VFR CONDITIONS WILL PREVAIL THROUGH THIS TAF PERIOD.
COMPLEX OF STORMS OVER CENTRAL IOWA IS EXPECTED TO FOLLOW THE
INSTABILITY GRADIENT AND SLIDE TO THE SOUTHEAST THIS AFTN.
MENTIONED VCTS FOR THE MID/LATE AFTN AT KCID/KBRL. ALTHOUGH BETTER
CHANCES ARE AT KBRL...WHICH ARE STILL RELATIVELY LOW.

A SECONDARY ROUND OF SHOWERS/STORMS IS POSSIBLE BEGINNING EARLY
TUESDAY MORNING AS LOW-LEVEL WAA INCREASES AHEAD OF A COLD FRONT.
TAFS REFLECT BEST CHANCES FOR PRECIP AT KCID/KDBQ...KEPT
CONDITIONS ON THE VFR/MVFR THRESHOLD FOR NOW.
UTTECH

&&

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

$$

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


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