Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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855 FXUS63 KDVN 201942 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 242 PM CDT Thu Jun 20 2024 .KEY MESSAGES... - A chance for isolated storms this afternoon and evening. Severe weather not anticipated. Locally heavy rainfall possible. - Hot and humid Friday and especially Saturday. - A chance for severe thunderstorms Saturday and Saturday night. && .SHORT TERM /THROUGH FRIDAY/... Issued at 241 PM CDT Thu Jun 20 2024 Tonight...Light sfc flow with several embedded boundaries seen on sfc observations and RADAR loops. Afternoon heating has made for 2000+ J/kg MUCAPEs, and with convective temps of mid to upper 80s, weak ridge-riding vort aloft, the buoyancy will be allowed to translate into isolated to widely sctrd showers and thunderstorms through mid evening. While widespread severe storms not expected with weak shear and lapse rates, can`t rule out pop and drop isolated downburst winds doing some shenanigans here or there. Also an environment favorable for non-supercell funnels. PWATs remain very high from 1.8 to 2 inches acrs the area, thus any more substantial cell will be very heavy rainer`s as they drift by. After some cloud thinning and evening storms fade, ongoing light sfc wind flow and juiced sfc DPTs there may be some patchy fog in spots, especially along any lingering boundary. Will place patchy fog wording in the north for now. Low temps in the upper 60s to low 70s for most of the area. Friday...High pressure aloft will look to bump up acrs the southeastern CWA, while periphery thermal ribbon-storm track setting up around this feature from the northern plains over to the Great Lakes, keeping the brunt of the MCS storm track northwest and north of the local area possibly into Sat morning. But lingering boundary north of I-80 or even Hwy 30, or possibly outflow from convective activity to the north or northwest, may be enough to bump up buoyancy-driven isolated storms in these areas Friday afternoon. Thermal profiles support highs in the upper 80s to low 90s, but sfc DPTs are still looking to mix out in the mid to upper 60s, thus the lower humidity should not warrant a heat advisory. But with the somewhat reduced humidity, there may be a better chance for ambient temps to reach the mid 90s in some locations with full sun or limited CU. Friday night, a low chance of upstream MCS activity to bleed down toward the northwestern CWA late night or just before dawn Saturday morning. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Issued at 241 PM CDT Thu Jun 20 2024 Saturday and Sunday...A hot and more humid airmass Saturday with highs in the low to mid 90s. Of course any cloud or convective debris lingering out of Friday night or coming in the form of initially decaying storms from upstream in the morning may make temps warm up potential tricky in some locations. Sfc DPTs may hang closer to 70 thus making heat indices push the upper 90s or near 100. Synoptic flow ensembles still keep the same signal of a vigorous northern stream short wave digging against the upper ridge and heat dome, with an associated sfc cold front acrs the region on Saturday. Stronger forcing/shear breaking the EML and plowing into high CAPEs likley will spark strong to severe, heavy rain producing storms later Saturday and into Saturday night. It`s still early but currently indicated CAPE and shear profiles would support damaging winds, large hail and isolated tornadoes. In the wake of the Saturday cool front and storms, incoming upper MO RVR Valley ridging and northwest flow may make for a dry, not quite as hot and less humid Sunday. Still looking like the best day of the weekend. Sunday night still under the influence of the sfc high and we may have low temps cool well down in the 60s by Monday morning. Monday through Wednesday...Latest run medium range ensembles and upper jet patterns suggest broad upper ridge amplification acrs the Rockies and western CONUS early next week. Resultant northwesterly steering flow acrs the upper MS RVR Valley into the GRT LKS may place the DVN CWA close to the ridge-riding short wave storm track, thus possibly subject to occasional convective systems. Thus may be a unsettled stretch this period especially Tue or Tue night. But one change in the latest runs was being more bullish in pumping up the Rockies upper ridge out west, resulting in more of a southward surge in LLVL ridging dumping down the upper to mid MS RVR Valley and western GRT LKS, for a cooler and dry reprieve from the early week warmth/storms. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1249 PM CDT Thu Jun 20 2024 Some lingering MVFR CIGs through mid afternoon, but most areas should lift to VFR by 3-4 PM. Isolated to widely sctrd showers and thunderstorms may pop up mid to late afternoon, and linger through at least mid evening. Hard to time and pin-point location with the low coverage, but just covered the suspected timing windows with VCNTY periods in the TAFs. Light and variable sfc wind regime this afternoon and much of the night. There may be some patchy fog under any clear skies late tonight, but not enough confidence to place in the TAFs at this time. VFR Friday morning away from any fog, with south to southwesterly sfc winds increasing to 5-10 KTs by late morning. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...12 LONG TERM...12 AVIATION...12