Severe Thunderstorm Warning 119, NWS Quad Cities, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
225 AM CDT SUN JUL 2 2000

LATEST ANALYSIS SHOWS NEXT WET PERIOD APPROACHING.  SURFACE FEATURES
SHOW DEVELOPING LOW PRESSURE IN WESTERN SD.  MODERATELY STRONG COLD
FRONT ATTACHED TO LOW EXTENDING FROM NEAR DULUTH BACK TO LOW NEAR RAPID
CITY.  GOOD LOW LEVEL CONVERGENCE PRODUCING STRONG CONVECTION ALONG
BOUNDARY AND AHEAD OF LOW IN SOUTHERN MINNESOTA AND BACK INTO SD. UPPER
VORT MAX NOTED ON SATELLITE AND UPPER AIR OVER FAR WEST SD TO HELP
ENHANCE CONVECTION. HEIGHT AND PRESSURE TENDENCY FIELDS SUPPORT COMPLEX
DEVELOPING/MOVING SE TOWARD CWA THROUGH EARLY MORNING TODAY.  BROKEN
CONVECTION NOTED LAST COUPLE HOURS DEVELOPING IN WEAK WARM FRONT AHEAD
OF SYSTEM ALONG MISSOURI RIVER VALLEY FROM SE SD BACK TO NEAR OMAHA TO
EVENTUALLY MERGE AND STEER SYSTEM SE.

...CLOUDS AND PRECIP WITH TODAY AND THROUGH MONDAY MAIN ISSUE WITH
IMPACTS ON TEMPS...

MODELS INITIALIZE WELL ON LARGER FEATURES AND VERIFY ADEQUATELY AT 06Z
WITH NORMAL CAVEAT ON INHERENT LIMITATIONS OF EACH MODEL WITH
CONVECTION. WILL USE ALL THREE MODELS WITH NGM FOR BROKEN CONVECTION
POTENTIAL TODAY ALONG APPROACHING WARM FRONT AND ETA/AVN FOR MAIN AREA
OF CONVECTION AHEAD OF NORTHERN PLAINS SYSTEM MODIFIED BY NOWCAST TOOLS
AND CONCEPTUAL CONVECTIVE MODELS AT ZONE ISSUANCE TIME. ALL MODELS
SUGGEST MODERATE TO LOCALLY HEAVY PRECIP WITH VERY MOIST AIR TO TAP AS
SD VORT MAX MOVES EAST AND THEN SE. AVN/ETA SHOW EVIDENCE OF ANOTHER
GREAT LAKES ENHANCED COLD FRONT LATE SUNDAY INTO MONDAY AS VORT MAX
HEADS SE OF REGION.  THIS WOULD HAVE MAJOR IMPACTS TO TEMPS AND POPS AND
CLOUDS IN LATER PERIODS. THIS LOCAL FEATURE HAS OCCURRED AT LEAST 5
TIMES THIS SPRING SO SEE NO REASON FOR NOT TO OCCUR AT LEAST ONE MORE
TIME. CHECK OF LATEST TEMPS OVER LAKE MICHIGAN RUNNING UPPER 50S TO
LOWER 60S TO REINFORCE FRONT AS DRAPES OVER REGION BEHIND FRONT. THUS...
GOOD POTENTIAL FOR MAJOR IMPACTS TO FRONTAL STRENGTH AND HIGH TEMPS
MONDAY.

TODAY...LATEST EXTRAPOLATION SUGGESTS COMPLEX TO REACH NW PORTIONS OF
ZONES ALONG WITH WARM FRONT BY MID MORNING.  EXPECT PARTLY CLOUDY SKIES
AHEAD OF COMPLEX SO SOME WARMING EXPECTED AND CHALLENGE IS THE AMOUNT OF
HEATING TODAY. CLOUDS AND HIGH MOISTURE SUGGEST ETA 2M TEMPS TOO HIGH
AND WILL GO WITH BLEND OF FWC/FAN. HIGH DEWPOINTS AND TEMPS SHOULD REACH
WELL INTO 80S TO SUPPORT CAPES OF 2500 TO 3500 J/KG AND S TO SW 850
WINDS OF 25-30KTS SO ENOUGH INSTABILITY AND FORCING ALONG BOUNDARY TO
SEE SOME WIDELY SCATTERED SEVERE POTENTIAL. THEREFORE...PLAN TO MENTION
SEVERE AND HEAVY RAIN. FORTUNATELY...TODAY/S FLASH FLOOD GUIDANCE HAS
IMPROVED DUE TO DRY WEATHER PAST 4-5 DAYS AND SHOWS MOST AREAS CAN TAKE
AT LEAST 2 INCHES SO SEE NOT ENOUGH POTENTIAL FOR FLASH FLOOD WATCH
TODAY AS COMPLEX SHOULD MOVE SE ALONG MODERATE BAROCLINIC ZONE LIMITING
AREA QPF TO BELOW GUIDANCE. POPS...PLAN ON 40-50 PERCENT MOST AREAS
TODAY EXCEPT LIKELY NORTH...MAY ADJUST DEPENDING HOW COMPLEX EVOLVES
NEXT COUPLE OF HOURS.

TONIGHT...ETA/AVN SHOW GOOD SUPPORT FOR REDEVELOPMENT OF CONVECTION LATE
AFTERNOON AND INTO EVENING WITH ONCE AGAIN CHANCE OF SEVERE AND HEAVY
RAINS...ESPECIALLY EARLY.  GO WITH MOSTLY CLOUDY FROM CONVECTION AND LOW
TEMPS AT OR ABOVE GUIDANCE DUE TO CLOUDS AS NE WINDS DON/T ARRIVE INTO
NORTH PORTIONS TIL EARLY MONDAY. POPS...LIKELY SOUTH AND HIGH CHANCE
NORTH.  DEPENDING ON QPF TODAY WITH FIRST SYSTEM...SOME AREAS MAY
EXPERIENCE REPEAT RAINS TONIGHT WHICH MAY CAUSE SOME FLASH FLOODING
POTENTIAL WHICH DAY FOLKS CAN CONSIDER LATER TODAY IF NEEDED.

MONDAY AND MONDAY NIGHT...FRONT TO STALL FAR SOUTH CWA WITH EAST WINDS
AND LOTS OF CLOUDS.  WILL KEEP CHANCE POPS WITH MAX TEMPS AT OR BELOW
MAV GUIDANCE AND WELL BELOW ETA/FWC AND EVEN FAN DUE TO CLOUDS AND LAKE
ENHANCED COOL AIR SO UPPER 70S NORTH TO LOWER/MID 80S SOUTH.  MONDAY
NIGHT WILL KEEP CHANCE POPS AS FRONT STAYS IN AREA AND POTENTIAL FOR
CONVECTION ALONG BOUNDARY. TEMPS NEAR FWC/FAN.

...EXTENDED...
LATEST MEDUIM MODELS SUPPORT WARM TUESDAY/WEDNESDAY WITH CHANCE OF
SHOWERS AND THUNDERSTORMS.  CANADIAN HIGH MOVES DOWN THURSDAY PER LATEST
UKMET AND CANADIAN.  WILL TRY AND PEAK AT MRF BEFORE ISSUANCE. SEE
LITTLE CHANGES TO CURRENT EXTENDED EXCEPT POSSIBLY COOLING AND DRYING
TREND POTENTIAL AT THIS TIME ON THURSDAY.

THANKS FOR COORDINATION WITH KDMX...KARX.

.DVN...
IA...NONE.
IL...NONE.
MO...NONE.

NICHOLS