957 FXUS63 KDVN 301030 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 530 AM CDT Fri Jun 30 2023 ...AVIATION UPDATE... .UPDATE... Issued at 522 AM CDT Fri Jun 30 2023 The Dense Fog Advisory has been expanded up toward the highway 30 corridor. Previous Update: Issued a Dense Fog Advisory roughly along/south of I-80 until 8 AM this morning. Several reporting sites have dropped to 1/4 mile visibility due to the fog and have not improved since cirrus clouds have overspread the area over the past few hours. The low- level atmosphere is very moist from the recent rainfall and surface winds are too light to lead to any boundary layer mixing. Expect areas of fog to continue into early this morning and become locally dense, especially in low-lying areas. The fog is not expected to be as widespread to the north of I-80, so will message with a Special Weather Statement in this portion of the forecast area. && .SHORT TERM...(Today and tonight) Issued at 300 AM CDT Fri Jun 30 2023 Today Key Messages: *Another chance for showers and thunderstorms today; SPC has a slight risk (2 of 5) for severe storms along/south of highway 34 and a marginal risk up to I-80 *Primary severe threat is strong straight line winds mainly across the southern portion of the outlook area (counties along and south of highway 34) *Warm and humid with highs in the mid to upper 80s Attention turns to a few clusters of storms that are currently over eastern Nebraska and north-central Kansas, positioned on the convergent portion of a nocturnal low-level jet. Latest hi- res guidance has slowed down the arrival of this convection as it tracks through central Iowa toward our outlook area. Best estimate on arrival time locally would be during the mid/late morning across the far west/southwest to early afternoon along or east of the Mississippi River. Recent CAM runs vary considerably regarding the strength of this complex of storms as it rolls across the southern few tier of counties of the forecast area and across portions of northern Missouri. If the system can become organized as downstream instability increases to 1000-1500+ J/kg (per HREF SBCAPE) during late morning to early afternoon period, then strong to severe wind gusts would be possible. Current assessment is that today's setup is not as volatile as yesterday's with mid-level lapse rates near 7 C/km or slightly lower and less SBCAPE to work with. Confidence remains low on how the convection will evolve because instability is not expected to be very high. For this reason, the Slight Risk from SPC seems appropriate at this juncture given the uncertainty. Later shifts will have to monitor closely and may have to increase chances for rain to the likely category roughly I-80 corridor and points to the south. Tonight Yet another chance for redevelopment of scattered showers and storms is forecast for the overnight period. Model consensus holds the better chances off until near or after midnight which should limit the overall severe threat with this round. Instead the focus may be mainly on the potential for more beneficial rainfall of 0.25 - 0.50"+! Unfortunately, it doesn't look like a widespread heavy rain with activity likely remaining scattered. .LONG TERM...(Saturday through Thursday) Issued at 300 AM CDT Fri Jun 30 2023 Key Messages: 1. Active weather pattern continues through the weekend, with several chances of showers and thunderstorms and some much needed rainfall. Latest drought monitor released today showed an increase in severe drought conditions. 2. Warm and mostly dry weather expected early next week for the 3rd and 4th of July. Discussion: A positively tilted longwave trough will track over the Great Plains into Iowa this weekend. Large scale ascent with this wave in a very moist and high theta-e environment, will bring several rounds of showers and thunderstorms to the region. While there is still a lot of differences in projected totals, model ensembles and the NBM all support much of the area receiving at least an inch of rain this weekend. NBM probs of 1+ inch of rain are highest along and south of highway 30. This is good news to drought stricken areas, which has continued to worsen in recent weeks. For those with holiday weekend activities, not all of the weekend will be wet. The highest chances of rain (50-75%) at this time will be in the Saturday afternoon-Sunday morning time frame. Extensive cloud cover and rain will keep highs cooler this weekend, with readings in the low to mid 80s. Early Next Week...building heights aloft and weak high pressure will bring warm and mostly dry conditions to the area. This will be ideal for holiday festivities, with highs in the upper 80s/low 90s and lows in the low to mid 60s. Dewpoints are expected to remain in the 60s, making it feel not too humid. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) Issued at 522 AM CDT Fri Jun 30 2023 Areas of fog will lead to periods of MVFR/IFR visibilities early this morning before quickly dissipating by the mid morning hours. The fog will remain shallow but could become locally dense. There is a chance for another round of showers and storms later this morning through the early afternoon as a complex moves west to east through eastern Iowa and northwest Illinois. Confidence is moderate on showers and embedded storms impacting portions of the area today. Have included TEMPOs in the TAFs to message thunder potential at CID/MLI/BRL. Gusty winds could accompany these showers and storms. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...Dense Fog Advisory until 8 AM CDT this morning for Cedar-Clinton- Des Moines-Henry IA-Jefferson-Johnson-Keokuk-Lee-Louisa- Muscatine-Scott-Van Buren-Washington. IL...Dense Fog Advisory until 8 AM CDT this morning for Bureau- Carroll-Hancock-Henderson-Henry IL-McDonough-Mercer-Putnam- Rock Island-Warren-Whiteside. MO...Dense Fog Advisory until 8 AM CDT this morning for Clark- Scotland. && $$ UPDATE...Uttech SHORT TERM...Uttech LONG TERM...Gross/Uttech AVIATION...Uttech