Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 251750
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1250 PM CDT SAT JUL 25 2015

.UPDATE...
ISSUED AT 1210 PM CDT SAT JUL 25 2015

MORNING CLOUD COVER FROM CONVECTION HAS RESULTED IN COOLER TEMPS
MANY AREAS SOUTH OF I-80... WITH WEST/NORTHWEST WINDS DRAWING
IN SLIGHTLY DRIER AIR SOME LOCATIONS. WITH GENERALLY HIGHS IN THE
UPPER 80S AND DEWPTS IN THE LOWER 70S... COMING UP WITH MAX HEAT
INDEX VALUES BELOW ADVISORY CRITERIA (100) AND MOSTLY IN THE
LOWER TO MIDDLE 90S. AS A RESULT... HAVE CANCELLED THE HEAT
ADVISORY. THIS IS NOT TO SAY THAT IT WONT BE VERY WARM AND
HUMID... AS IT WILL... BUT NOT EXPECTING HEAT INDEX VALUES TO
PEAK AT OR ABOVE 100 DEGREES. OTHERWISE...REST OF THE AFTERNOON
LOOKS MAINLY QUIET WITH JUST A SLIGHT CHANCE OF A SHOWER OR STORM
LATE PM NEAR TO SOUTH OF I-80 WITH BOUNDARY AND IF CONVECTIVE
TEMPS NEAR 89 DEGREES BREACHED. UPDATED GRIDS/PFM/ZPF/NPW ISSUED.

&&

.SYNOPSIS...
ISSUED AT 330 AM CDT SAT JUL 25 2015

THUNDERSTORM COMPLEX MOVING THROUGH NORTHEAST MO SOUTH OF THE DVN
CWA WHILE ANOTHER LARGER MCS WAS MOVING ACROSS SW IA/NW MO. THIS
IS IN A NICE LOW LEVEL MOISTURE TRANSPORT WITH PWAT`S AROUND 2
INCHES. 3 AM TEMPERATURES RANGED FROM THE MID 60S TO LOWER 70S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT SAT JUL 25 2015

HEADLINES...HAVE ISSUED A HEAT ADVISORY NOON TO 8 PM FOR LOCATIONS
ROUGHLY ALONG AND SOUTH OF INTERSTATE 80.

TODAY...SPC 4.0 KM WRF-NMM TAKES THE MCS MOVING ACROSS SOUTHERN
IA INTO OUR SOUTHERN CWA THIS MORNING...SOME OF THESE STORMS MAY
BE SEVERE. THE MCS SHOULD MOVE EAST OF THE CWA BY NOON ALLOWING
FOR PLENTY OF SUNSHINE THIS AFTERNOON WHICH SHOULD PUSH
TEMPERATURES WELL INTO THE 80S TO AROUND 90. THIS COMBINED WITH
DEWPOINTS AT LEAST IN THE MID 70S WILL CREATE HEAT INDEX VALUES IN
THE UPPER 90S TO POSSIBLY NEAR 105.

TONIGHT...MCS GENERATION TOOL BRINGS ANOTHER MCS ACROSS ROUGHLY
OUR SOUTHERN HALF LATER TONIGHT. THIS MAY PRODUCE SEVERE WEATHER
ALONG WITH LOCALLY HEAVY RAINFALL. LOWS WILL BE IN THE UPPER 60S
TO LOWER 70S.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 330 AM CDT SAT JUL 25 2015

SUNDAY MORNING...THE SOUTHERN THIRD OF THE FORECAST AREA STANDS THE
BEST CHANCE TO RECEIVE A ROUND OF SHOWERS AND THUNDERSTORMS AS NOSE
OF 850MB LOW-LEVEL JET VEERS FROM SOUTHWEST IOWA TOWARD THE EAST.
HIGHEST POPS ARE IN THE 50-60 PERCENT RANGE...TAPERING TO 30-40
PERCENT FURTHER NORTH. THE ECMWF MCS PARAMETERS ARE MOST AGGRESSIVE
WITH BRINGING A STORM COMPLEX INTO THE AFOREMENTIONED AREA...OTHER
MODELS MUCH LESS SO...MAKING THIS A DIFFICULT FORECAST WHERE
CONFIDENCE LIKELY WILL NOT INCREASE UNTIL SATURDAY EVENING.

SUNDAY AFTERNOON AND EVENING...LATEST MODEL TRENDS HAVE BEEN TO
WEAKEN A CONVECTIVELY INDUCED VORTICITY MAX WHICH WILL FIRST DEVELOP
OVER EASTERN SOUTH DAKOTA LATE SATURDAY NIGHT AND DRIFT INTO
SOUTHERN MINNESOTA BY SUNDAY MORNING. CHANCES FOR SHOWERS/STORMS
FROM LATE SUNDAY MORNING THROUGH THE AFTERNOON WERE CLOSELY TIED TO
THE STRENGTH OF THE VORTICITY MAX. FOR THIS REASON...HAVE DECREASED
RAIN CHANCES SUNDAY AFTERNOON TO THE CHANCE CATEGORY...BETWEEN
20-40 PERCENT...AND DO NOT FORESEE WIDESPREAD CONVECTION.

OTHERWISE...HEAT INDICES COULD PEAK NEAR 100 F ALONG AND SOUTH OF
HIGHWAY 34.

SEVERE STORM POTENTIAL...LATEST SPC OUTLOOK IS A MARGINAL RISK FOR
SEVERE STORMS OVER SOUTHWEST ONE-HALF OF THE CWA. THE ABSENCE OF
A FORCING MECHANISM FOR ASCENT SUPPORTS THE IDEA THAT SEVERE
STORMS IF THEY OCCUR WILL REMAIN ISOLATED.

MONDAY...HUMID CONDITIONS WILL CONTINUE WITH DEWPOINTS IN THE 70S
AND HIGHS IN THE MID/UPPER 80S. MOST AREAS WILL LIKELY REMAIN DRY
THROUGH THE DAY AS MID-LEVEL RIDGING BUILDS OVER THE MIDWEST...BUT
AN ISOLATED SHOWER OR STORM IS POSSIBLE DURING PEAK DAYTIME HEATING.

TUESDAY...UNSEASONABLY STRONG UPPER LOW DEVELOPING ACROSS
SASKATCHEWAN/MANITOBA/ONTARIO IS FORECAST TO ADVECT VERY WARM AIR
ALOFT OVER THE MIDWEST...SETTING UP ANOTHER DAY OF HIGH HEAT INDICES
NEAR OR OVER 100 F. FORECAST SOUNDINGS INDICATE DEEP BOUNDARY
LAYER MIXING POTENTIALLY UP TO 800MB...CREATING BREEZY SSW WINDS
AT THE SFC. BOTH THE GFS/ECMWF HAVE 850MB TEMPS IN THE LOWER TO
MIDDLE 20S CELSIUS AND 1000-500MB THICKNESSES NEAR 584 DAM.

WEDNESDAY THROUGH FRIDAY...THERE WILL BE A PATTERN CHANGE TO MUCH
LESS HUMID AND MAINLY DRY WEATHER BEHIND A COLD FRONT THAT IS
FORECAST TO COME THROUGH ON WEDNESDAY. DEWPOINTS SHOULD FALL
THROUGH THE 60S AND COULD BE IN THE 50S AT TIMES. A WARMING TREND
MAY COMMENCE BY FRIDAY DUE TO SOUTHWEST RETURN FLOW. HIGH TEMPS
SHOULD AVG IN THE 80S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1241 PM CDT SAT JUL 25 2015

AN UPPER LEVEL DISTURBANCE AND FRONTAL BOUNDARY DRAPED ACROSS THE
AREA WILL SERVE AS THE FOCUS FOR CHANCES OF SHOWERS AND STORMS
MAINLY LATER THIS EVENING THROUGH SUNDAY MORNING. UNCERTAINTY
EXISTS AS TO COVERAGE WHICH IS LARGELY RELATED TO WHETHER OR NOT
THE CONVECTION IN THE PLAINS GROWS UPSCALE INTO AN ORGANIZED
COMPLEX OF STORMS. THUS...HAVE LIMITED PRECIP MENTION TO ONLY
PROB30 GROUPS FOR NOW AT MOST SITES HIGHLIGHTING MOST FAVORED
TIMING OF LATE TONIGHT INTO SUNDAY MORNING. HOWEVER AT BRL SIDED
TOWARD TEMPO GROUP WHERE BETTER SIGNAL FOR PRECIP EXISTS WITH
FRONT AND ALSO BEING MOST FAVORED LOCATION FOR TRACK SHOULD
ORGANIZED CONVECTION DEVELOP. ANTICIPATE CONDITIONS TO LOWER INTO
MVFR TO IFR IN FOG AND PRECIPITATION LATE TONIGHT AND SUNDAY
MORNING. LIGHT NORTHERLY WINDS EXPECTED TO VEER EASTERLY TONIGHT
INTO SUNDAY MORNING.

&&

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

$$

UPDATE...05
SYNOPSIS...HAASE
SHORT TERM...HAASE
LONG TERM...UTTECH
AVIATION...05



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