Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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369 FXUS63 KDVN 101924 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 224 PM CDT Fri May 10 2024 .KEY MESSAGES... - Gusty winds are still possible with showers and isolated thunderstorms this evening. Clouds should clear later this evening. - Warmest day in the next week or so will be Sunday with highs in the 80s. - Active long term as a series of waves makes its way through the area. && .SHORT TERM /THROUGH TONIGHT/... Issued at 224 PM CDT Fri May 10 2024 Mostly to party sunny skies were found across the area this afternoon. Temperatures in the mid to upper 60s were found area-wide. North of the area, another wave started moving into MN and N WI. A cold front with this wave was being pulled south into the area. This will serve as the main forecast problem in the short term. Two main things of interest are the chances for showers and thunderstorms this evening and how fast do clouds clear out after the cold front. Cold front timing and shower/storm timing have been rather consistent. Expect most of the showers/storms to enter the area between 01 and 02Z and exit our southeast by 05z to 07z. Clouds should clear quickly after the front moves through as drier air moves into the area. We currently have a clear forecast and I expect that to continue. That said, some CAA CU over MN behind the front does make me a little nervous, especially if it decides to turn to stratus, we could be out of luck with sky cover tonight. I do not see this happening, but we need to keep an eye on it as it would be the only way we aren`t clear. This evening, CAPE does build ahead of the front as dewpoints in the 50s start to pool ahead of it. This will help to develop thunderstorms, as the front moves south, cooling after the sun sets, should lead to a decrease in overall CAPE. This means the best chance for thunder will be across the far north as the showers and storms enter. With dry low levels, inverted V soundings are indicative of gusty winds with these showers. Wind gusts to 45 mph cannot be ruled out. With a decrease in CAPE overall risk for severe weather is so low that it doesn`t warrant a mention in the HWO. After this, a quiet Saturday is expected with similar temperatures to today. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Issued at 224 PM CDT Fri May 10 2024 Period will start out with short-lived ridging as a SW wave pulls warmer air into the area for Sunday. Temperatures into the low 80s are currently forecast. After this, guidance slowly brings this nearly cut-off SW wave across the area leading to an increase in rain and thunderstorm chances. Sunday afternoon we could see scattered showers and storms. While CAPE up to 2000 J/kg are possible, the shear is rather weak at 20-25 kts of deep layer. This suggests a multicell type of thunderstorm environment with strong storms. With the large T/Td spread could possibly see some strong to near severe gusts, especially if we can get that 2000 CAPE to develop. Tuesday On: There is uncertainty on how fast the rain moves out with most of the models lingering it across the south through Tuesday morning. Generally, we`ll be looking at a more tranquil pattern later Tuesday into Wednesday as a backdoor cold front advects in a cooler and drier air mass from the NE. NBM highs may be too warm for Wednesday, and latest trends in the deterministic models is to delay the next round of showers and storms until Wednesday night into Thursday. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1242 PM CDT Fri May 10 2024 VFR conditions are expected through the period. Expect a cold front and wind shift this evening. Some sites could see rainshowers as well. The better chance for this will be at the north TAF sites where -SHRA was added. There is a small chance that these sites could see some lightning as well, but left out at this time do to low confidence. && .HYDROLOGY... Issued at 846 PM CDT Thu May 9 2024 Changes... The flood watch for the Wapsipinicon River near De Witt has been changed to a flood warning. Discussion:Active period again with periodic rounds of showers and thunderstorms as another deep trough comes out of the Rockies and into the middle of the country. However, way too early to determine severe threats or rainfall amounts. Highs will be well into the 70s to around 80. The Cedar, Iowa and Wapsipinicon Rivers continue to rise as a result of the rainfall over the past 30 hours. The forecast for De Witt has not changed much over the past 24 hours, thus confidence has increased that it will reach flood stage within the next 24 hours. The overall situation with the Cedar and Iowa Rivers is more uncertain. While there is a better accounting of the overall runoff compared to 24 hours ago, the forecast for Marengo on the Iowa river is just barely above flood stage. Since the flood crest will gradually attenuate due to gravity as it moves downstream, there is a 30 to 40 percent chance that the crest at Marengo may occur just below flood stage. On the Cedar River near Conesville the flood crest will also attenuate as it moves downstream. However, the crest is further above flood stage which means there is a 50 percent chance of reaching flood stage. Rainfall over the next 72 hours and where it occurs will be the deciding factor as to whether or not the Cedar and Iowa Rivers will reach flood stage near Conesville and at Marengo respectively. If the rainfall is lighter than expected then river forecasts may be lowered. However, if rainfall is heavier than expected then river forecasts may be raised. .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...Gibbs LONG TERM...Gibbs AVIATION...Gibbs HYDROLOGY...8