Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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848 FXUS63 KDVN 041801 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 101 PM CDT Thu Jul 4 2024 .KEY MESSAGES... - Tricky forecast today with potentially strong to severe thunderstorms, that could impact 4th of July celebrations. - A rather active pattern still looks to be on tap through the longer range, with near daily chances for precipitation somewhere in or near our forecast area. Saturday may be the best chance at a dry day, with slight-chance PoPs daily from there. - Moderate to Major River Flooding continues, with further changes to river forecasts expected as we transition from predicted rainfall to observed rainfall over the next 36 hrs. && .SHORT TERM /THROUGH FRIDAY/... Issued at 300 AM CDT Thu Jul 4 2024 A complex, mesoscale driven day is expected today as questions about what happens this evening with showers and storms remains front and center. Convection south of the area this morning should move east of the area after 18z. At the same time another wave is expected to move towards the area from the NW. A cold front is expected to be dragged across the area by this wave later in the afternoon and into the evening. How the AM storms evolve will greatly affect the afternoon and evening storms. We may see some showers associated with the convectively enhanced wave/MCV moving south of us this AM. The clouds/showers this AM will determine whether or nature provides the fireworks tonight or not. So CAMs are all over the place, recent HRRR runs buy into a clearing this afternoon and redevelopment of showers and storms this afternoon that approach the area this evening, likely affecting firework displays. We need to keep an eye on the clouds, if we see decent clearing I think storms, that are strong to severe are plausible from 23z to 06z. If we don`t clear, there is enough largescale ascent that we could see isolated showers between 02z and 06z with the fropa. If we do get PM storms due to clearer skies, we do have a prime environment for severe weather. SPC has the area in a marginal risk, which is likely continent on the clearing skies. We do have 40-50kt deep layer shear that is perpendicular to the forcing boundary suggesting supercells are possible. Decent flow aloft may keep these storms supercellular instead of developing cold pools and forming lines. Think hail and damaging winds are main threat as llvl shear is not all that impressive. That said, I never count a supercell out on ability to produce a tornado, so there remains that threat as well. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Issued at 300 AM CDT Thu Jul 4 2024 To start the long term, an upper level low/trof is expected to swing through the area into Saturday AM. We could see some showers associated with this low on Friday. With the clouds associated with this low, we could see highs only in the 70s. Saturday into Sunday we continue to see an active flow with overall trofing across the area. A series of waves through this flow could bring pop chances to the area. Model guidance still suggests that Saturday will be the best chance for dry day this weekend. Early next week, a high amplitude ridge to our west builds. We see a deeper trof across our area that would lead to some scattered showers and storms. With the NW flow we should see temps be more seasonable if not slightly below normal. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1236 PM CDT Thu Jul 4 2024 A disturbance continues to lift northeastward across eastern Iowa early this afternoon. All TAF sites in eastern Iowa are VFR with ceilings between 6 to 10kft. Light showers are forecast to move across the area through mid afternoon with MVFR ceilings and visibilities possible in the strongest showers. Placed a tempo group at KCID, KDBQ, and KMLI to account for these showers. The focus then shifts to a line of storms that is forecast to develop and move from west to east between 02 and 08 UTC. Placed a prob30 group at all TAFs for a two hour windows as the line moves across the area. There is lower confidence in the intensity of these storms and the coverage especially for KBRL. Winds will switch to the west behind a cold front after 06 UTC with gusts winds developing after 12 UTC Friday. && .HYDROLOGY... Issued at 1211 PM CDT Wed Jul 3 2024 The forecasts along the Mississippi River havn`t changed much from the previous ones, with many forecast points cresting into the weekend. Locations from Dubuque to Keokuk are still expected to crest over their respective Major Flood Stage levels. At Gregory Landing, a crest in the Moderate category is forecast. The crest is forecast near Dubuque and Bellevue on July 4th and 5th, with sites from Fulton to Keokuk seeing a crest between July 6th and 8th. On the Maquoketa at Manchester, the heavy rains and training thunderstorms to produce them did not materialize and shifted to the south of that basin. Thus it is no longer expected to reach the minor flood stage and the warning has been cancelled. Also with the rainfall amounts not being quite as high or widespread as earlier anticipated in some of the more northern basins, several tributary forecasts have been toned down some. Ongoing river flood watches and warnings on the Cedar, Iowa, Wapsi, Skunk, and Maquoketa Rivers have been adjusted accordingly to the rainfall reports from this morning. But with a few other areas indeed receiving torrential rainfall a bit further south, the river flood watches for the North Skunk River near Sigourney and English River at Kalona have been upgraded to river flood warnings. Current projections for additional rainfall over the next few days through the end of the week look more spotty with widespread heavy rain not likely. This should help maintain the current forecasts from deviating too much from the most recent forecasts. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...Gibbs LONG TERM...Gibbs AVIATION...Cousins HYDROLOGY...12