Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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690 FXUS63 KDVN 160708 CCA AFDDVN Area Forecast Discussion...CORRECTED National Weather Service Quad Cities IA IL 208 AM CDT Mon Sep 16 2024 .KEY MESSAGES... - High confidence on above normal temperatures this week. - Confidence on timing of rain chances late week into the weekend is low, as an upper level ridge becomes reestablished across the region. && .SHORT TERM /THROUGH TUESDAY/... Issued at 200 AM CDT Mon Sep 16 2024 Pattern remains stagnant due to a Rex block out east formed between Great Lakes to Mid-Atlantic ridging and a low (Potential Tropical Cyclone 8 or PTC8) off the South Carolina coast. This low per NHC has a high chance of becoming a Tropical Cyclone while moving inland over the next 24+ hours. Please refer to the National Hurricane Center (NHC) for further information on this system. Despite the lack of movement of systems in this blocked pattern, we are tracking some changes (decrease) namely to moisture levels. Water vapor imagery reveals a large reservoir of dry air entrained in the mid/upper level ridge out east, and noted in PWAT analysis (PWATs around 0.5 to 0.7 inch across the Ohio Valley and Mid-Atlantic), which continues to make steady progress toward the region. DVN RAOB PWAT at 00z was 1.3 inches down from 1.6 inches 24 hours prior. We`ll continue to gradually pull in drier air in a couple of surges through Tuesday, as the mid level ridge edges a bit westward and low level flow advective flow continues from the E/SE. This will initially draw down the dew points with advection from the Ohio Valley region later today and tonight, followed by a secondary surge of drying to arrive Tuesday from the Appalachians. The result will be a more comfortable late Summer warmth, which will be noticed more in our eastern counties today (dew points dropping into the 50s) and then areawide on Tuesday (dew points lowering into the 40s/50s). The dry air will also support increased diurnal ranges, which means more comfortable nights with lows near or below deterministic NBM into the 50s and lower 60s. We`ll also continue to be above normal on daytime highs with readings from the mid 80s to lower 90s today and Tuesday. We`ll also have one more day with the low potential for isolated weak convection this afternoon, mainly across SE Iowa and NE Missouri within the low to mid level theta-e gradient. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Issued at 200 AM CDT Mon Sep 16 2024 The lingering Rex block in the eastern CONUS is progged to finally weaken early on, which is great news for our rain prospects right?!? Unfortunately, likely not so at least early on in the period, as the models quickly reestablish and amplify upper ridging over the region Wednesday and Thursday ahead of a western CONUS trough, and possibly longer. Trends from WPC cluster analysis of the 500 hPa pattern support the influence of the upper ridge holding on longer. NBM has pushed back PoPs to Thursday night through the weekend, but based on the cluster analysis and trends of the 500 hPa ridge strength and placement I wouldn`t be at all surprised to see further delay/slowing of the PoPs. As a result, confidence remains low with the timing of rain chances, until possibly sometime next weekend when there`s a signal for the ridge shifting eastward allowing for more influence of shortwave troughing. While timing of our next rain chances remains low confidence, what remains high confidence is a continuation of the unseasonable late summer warmth through at least late week. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1145 PM CDT Sun Sep 15 2024 VFR conditions and light E/SE winds are expected to persist through the period. Diurnally driven isolated weak convection is possible again Monday PM mainly well west of the Mississippi River. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...McClure LONG TERM...McClure AVIATION...McClure