648
FXUS63 KDVN 040801
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
300 AM CDT SAT JUL 4 2009
SYNOPSIS
BROAD AREA OF LOW PRESSURE IN THE CENTRAL PLAINS TO TRACK ACROSS THE
REGION TODAY. INTERESTING RADAR DISPLAY WITH SEVERAL BANDS OF RAIN
AND EMBEDDED THUNDERSTORMS MOVING EAST ACROSS IA...BUT WITH SEVERAL
SMALL CONVECTIVE SHOWERS EITHER NEARLY STATIONARY OR MOVING N TO NW.
BUT LOOKING AT WIND PROFILES THIS MORNING THIS MAKES SENSE.
STRONGEST THUNDERSTORMS SEEN ALONG THE I-70 CORRIDOR IN KS AND MO
NEAR WARM FRONT. RAIN WILL GRADUALLY END THIS AFTERNOON AS WAVE
MOVES AWAY FROM THE AREA. TEMPERATURES TO GRADUALLY WARM DURING THE
UPCOMING WEEK WITH THE NEXT COLD FRONT TO ARRIVE BY THE END OF NEXT
WEEK.
SHORT TERM...TODAY AND TONIGHT
A COOL WET 4TH OF JULY IN STORE WITH AREA OF LOW PRESSURE FROM
SOUTHEAST NEB INTO KS WITH THE BEST PRESSURE FALLS OCCURRING IN
SOUTHWEST IA. THERE IS A DECENT 40 KNOT LOW LEVEL JET SEEN ON
PROFILER DATA...COMBINED WITH LARGE SCALE ASCENT FROM SHORT WAVE
MOVING EAST OUT OF THE CENTRAL PLAINS. BANDS OF STRONG
FRONTOGENETICAL FORCING IN PLACE THIS MORNING BEFORE WEAKENING OR
MOVING EASTWARD THIS AFTERNOON. WILL INDICATE 80-90 POPS FOR
TODAY...GRADUALLY TAPERING OFF FROM NW TO SE THIS AFTERNOON. BANDS
OF SHOWERS AND ISOLATED THUNDERSTORMS SHOULD CONTINUE TO FILL IN
THIS MORNING WITH THE MAIN AREA OF THUNDERSTORMS EXPECTED ALONG AND
SOUTH OF HIGHWAY 34. WILL ALSO MENTION LOCALLY HEAVY RAIN IN THE
CONVECTIVE ELEMENTS WITH SURFACE DEWPOINTS IN THE MID 60S AND
PRECIPITABLE WATERS AROUND 1.8 INCHES. POTENTIAL FOR AN INCH OR TWO
OF RAIN IN LOCALIZED SPOTS BUT NOT EXPECTING ANY FLOODING PROBLEMS
WITH RATHER HIGH FFG. RAIN SHOULD BE OVER WITH BY LATE AFTERNOON
SO A DRY EVENING AND OVERNIGHT EXPECTED...JUST IN TIME FOR THOSE
FIREWORKS DISPLAYS. TEMPS TO BE HELD DOWN TODAY DUE TO RAIN AND
CLOUD COVER WITH MAX TEMPS MAINLY IN THE LOWER 70S...SOME 10 TO 15
DEGREES BELOW NORMAL FOR THIS DATE.
..HAASE..
LONG TERM...SUNDAY THROUGH NEXT FRIDAY
THE LONG TERM PORTION OF THE FORECAST WILL COVER THE TRANSITION FROM
NORTHWEST FLOW ALOFT...TO A ZONAL OR FLAT UPPER RIDGE LATER IN THE
PERIOD. THIS WILL RESULT IN A STEADY WARMING TREND...GOING A BIT
BELOW NORMAL SUNDAY AND MONDAY...TO HOT AND HUMID CONDITIONS FROM
MID TO LATE WEEK. IN ADDITION...THERE WILL BE A THREAT FOR
CONVECTION...ESPECIALLY FROM THURSDAY ONWARD AS PREDICTABLY HIGH
CAPE VALUES COMBINE WITH WAVES IN ZONAL FLOW...OR ONES OVERTOPPING
THE FLAT RIDGE ALOFT. SUNDAY AND SUNDAY NIGHT APPEAR DRY AT THIS
TIME...WITH LITTLE NOTABLE FORCING ALOFT. HOWEVER...THE PICTURE
GETS A BIT MORE COMPLICATED MONDAY AND MONDAY EVENING AS MODELS SHOW
A SHORT WAVE APPROACHING IN NORTHWEST FLOW ALOFT. WHILE SURFACE
PRESSURES REMAIN HIGH...THERE IS LITTLE CAPPING AND MODELS INDICATE
ENOUGH MOISTURE THROUGH H85 FOR THE POTENTIAL OF CONVECTION. A
FOCUSING MECHANISM IS LACKING...AND THEREFORE I WILL INTRODUCE ONLY
SLIGHT CHANCE POPS.
TUESDAY THROUGH WEDNESDAY NIGHT...THE UPPER FLOW SHOULD BECOME MORE
AMPLIFIED...WITH THE MAIN FORCING WELL NORTH OF THE CWA.
HOWEVER...BOTH THE 00Z GFS AND ECMWF CONTINUE TO INDICATE THAT THE
UPPER RIDGE WILL BECOME FLAT OR TRANSITION TO ZONAL FLOW...WITH JET
ENERGY LOCATED JUST TO OUR NORTH OVER THE GREAT LAKES. TEMPERATURES
HAVE THE POTENTIAL TO REACH THE LOWER 90S OVER THE ENTIRE AREA
THURSDAY AND FRIDAY...BUT THEY COULD EASILY BE HELD BACK BY SHOWERS
AND THUNDERSTORMS AS WELL. NO CHANGES HAVE BEEN MADE TO THESE
PERIODS BEYOND MONDAY NIGHT...BUT IN GENERAL ANOTHER ACTIVE SUMMER
REGIME SHOULD DOMINATE THE EXTENDED FORECAST. ...ERVIN...
AVIATION
WIDESPREAD SHOWERS AND A FEW EMBEDDED THUNDERSTORMS TO COVER EASTERN
IA FOR MUCH OF TODAY...BUT GRADUALLY ENDING BY LATE AFTERNOON FROM
NW TO SE. MVFR CIGS/VIS MUCH OF TODAY BUT BECOMING VFR BY LATE
AFTERNOON CONTINUING SATURDAY NIGHT.
..HAASE..
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
HAASE/ERVIN
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