Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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586 FXUS63 KDVN 130552 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 1252 AM CDT Tue Aug 13 2024 ...06z Aviation Update... .KEY MESSAGES... - There will be the potential for dense fog tonight through much of the area, which may lead to AM commute impacts if it becomes widespread. River valleys and low-lying areas remain the areas with the best chance. - Active stretch of weather ahead of us, with near daily chances for precipitation somewhere in our area. Best chances for more widespread showers/storms will be midweek and beyond. - Temperatures trending near normal by midweek, with most in the low- mid 80s. && .SHORT TERM /THROUGH WEDNESDAY/... Issued at 155 PM CDT Mon Aug 12 2024 Aside from the remnant showers being seen in the south, we are geared up for a quiet and dry 24-48 hours. As this wave pushes out this evening, we will start to see weak ridging and high pressure work into the area. With LLVL moisture still around, along with recent rainfall, we may see fog for some. Areas that are cloudless tonight are expected to drop into the mid 50s, with those socked in clouds sticking around 60. Tomorrow, a beautiful day is ahead of us. A weak surface high pressure will pass through tonight and tomorrow AM, with LLVL winds shifting southeasterly. So, we will start to see some more seasonable temperatures work in tomorrow, with much of the area in the low-mid 80s. Areas in the south may still be fighting cloud cover, which would make them slighly cooler than the remainder of the area, generally keeping them closer to 80. In all, much of the area will be mostly clear and dry, with the clouds decreasing in the south through the afternoon. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Issued at 155 PM CDT Mon Aug 12 2024 An active period of weather is likely Wednesday into Thursday as an upper-level trough approaches the area. Though models disagree on exact timing and location, widespread showers and storms are likely to impact our area during the Wednesday night/Thursday timeframe. Wednesday itself will feature comfortable temperatures and humidity levels with scattered rain chances, highest east. Attention then turns to Wednesday night as the low-level jet begins to ramp up, increasing moisture and theta-e transport into the area. Guidance agrees on a strong shortwave approaching overnight, favoring the development of an MCS. Most guidance develops impressive moisture by this time, with PWATs at or above 2.00". Given our past rainfall events this summer, confidence is low on exceeding that 2.00" PWAT, as we have typically underperformed compared to guidance prior. That being said, unseasonably high moisture in the column (PWATs greater than the 90th percentile) would certainly support heavy and efficient rainfall with any thunderstorms. When all is said and done, we`re looking at a healthy swath of 1 to 2 inches of rainfall across the area, with higher amounts in areas that see repeating thunderstorms. Because of this, the WPC Day 3 ERO (12z Wednesday through 12z Thursday) highlights the southwest two-thirds of our CWA in a slight risk for excessive rainfall, with the remainder of the area in a Marginal risk. With the first part of August being quite dry compared to normal along with negative soil moisture anomalies, the area is in generally good shape to handle a widespread soaking. However, with such great forcing and moisture transport into our area, localized flash flooding is definitely a possibility with any training thunderstorms. Showers and thunderstorms once again are possible on Thursday and into Thursday evening, though confidence is lower on how Thursday will evolve with the potential for remnants/boundaries from early morning convection to complicate things. There exists the potential for a triple point severe threat on Thursday, though confidence is low in this at this range. Guidance diverges on temperatures for Thursday, with confidence being tied to convective evolution. With dew points in the 70s and temperatures likely in the 80s, it is possible we could see some heat indices pushing 90-100F in our southern CWA on Thursday. Looking ahead to Friday and through the weekend, the GFS and ECMWF both cut the upper low off over the Great Lakes region which would put us into a quieter northwest flow pattern. As a result, CAA should keep temperatures to near normal with humidity moderating. There will be a few slim chances for wrap-around precipitation (<30%) over the weekend from the cut-off low, with the best chances on Saturday. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1245 AM CDT Tue Aug 13 2024 VFR level stratocu continues to hang on along and south of I-80 and may do so through dawn. This may limit the fog in these areas, but with some holes possible and ongoing light/variable sfc wind regime will still advertise at least MVFR fog in these areas. Elsewhere where there is less cloud cover, MVFR to IFR fog pockets still possible toward dawn but the situation is a bit uncertain. As Tuesday progresses, after any fog or temporary low CIGs from fog lift or low stratus seep from central IA clear out, expect a mainly VFR day into Tue evening. The light and variable to calm sfc wind regime will trend to the southeast at 4-7 KTs by Tue afternoon. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...Gunkel LONG TERM...Gunkel AVIATION...12