Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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486 FXUS63 KGRR 191742 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 142 PM EDT Wed Jun 19 2024 .KEY MESSAGES... - Hot/humid today with a chance of storms - Not as hot Thursday - Sct`d storms Friday through Sunday; highest chance Saturday night - Hot and Breezy Saturday - Dry and more comfortable Sunday through Tuesday && .UPDATE... Issued at 1054 AM EDT Wed Jun 19 2024 The 12z KDTX sounding showed thicker CAPE just below the -20 deg C level and DCAPE values around 750 J/kg. Already we had one cell just south of Jackson County that some indications of hail. With PWAT`s running over 1.8 inches near that cell, and a relatively slow movement, it`s not surprising that locally over an inch of rain fell with it. Looking at the afternoon, we will continue to destabilize. Bulk effective shear values were elevated(30kts) over southeast parts of the CWA. DCAPE was highest along the I-96 corridor with values topping 1000 J/kg. High res models like the HRRR and NAM 3km have been showing convection developing over south to southeast parts of Lower MI this afternoon with outflows lifting northward through the late afternoon hours. Some of these may collide leading to additional convective development. Given the favorable DCAPE and mid level CAPE near the -20 deg C level, gusty winds and hail may accompany any stronger convection. Locally heavy rainfall will be possible as well. Heat index values were nearing 90 degrees already. Most locations in the headline area should end up in the 93 to 98 degree range this afternoon. && .DISCUSSION... Issued at 322 AM EDT Wed Jun 19 2024 - Hot/humid today with a chance of storms Another hot and humid day is expected. As of 3am, it`s still 82 at Holland. Needless to say, temperatures won`t have to rise much to reach the 90s today. As dewpoints close in on 70 this afternoon, heat indices will rise into the mid to upper 90s. CAMs show a seasonably robust short wave lifting north today from the MO bootheel. As it arrives this afternoon, we`ll see isolated convective develop within a weakly sheared environment that will see 1500 j/kg SBCAPE and PWATs near 2 inches. A marginal risk of severe storms exists for the southeast cwa mainly for the potential of gusty winds. - Not as hot Thursday GFS and ECMWF show a weak cold front dropping south tonight and northeast winds developing that will continue Thursday. It`s likely temperatures will be a little cooler Thursday with highs around 80 near US-10 to around 90 near I-94. If the cooler trend continues in the models, we may be able to drop the Heat Advisory. The ECMWF also showed weak low pressure riding east along the frontal boundary Thursday resulting in showers/storms over the eastern cwa. Given the humid environment in place, any storms that develop will be capable of producing heavy rain. - Sct`d storms Friday through Sunday; highest chance Saturday night The center of the upper high continues to drift southwest over the weekend, from the TN Valley on Friday to Texas by Sunday. Shortwaves riding around the periphery of the upper high combined with weak surface convergence and peaking afternoon/evening instability will continue to support a daily risk for showers and storms through the weekend. The highest chance of storms comes on Saturday night when a cold front presses southeast through the region ahead of an approaching nrn stream shortwave. Deep layer shear values will be ramping up by then as the influence of the upper ridge slips away so we may be looking at a round of severe weather as that system comes through. - Hot and Breezy Saturday Ahead of that cold front/shortwave a surge of even warmer air arrives for Saturday with guidance temps as suggesting readings as high as 95 well inland from Lk MI. Southwest winds may gust over 30 mph. - Dry and more comfortable Sunday through Tuesday It is that nrn stream shortwave which ushers in less humid and not as hot weather for a few days early next week with lows in the lower to mid 60s and highs in the lower 80s. Confidence in a dry Monday is fairly high as high pressure passes overhead, before low pops creep back in with returning warm air by midweek. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 142 PM EDT Wed Jun 19 2024 Main changes were to scale back thunderstorm chances this afternoon and evening. The best prospects for storms will be around JXN. Should storms occur in this area, they would likely be associated with outflow boundaries from other thunderstorms farther to the southeast. While JXN barely merits a VCTS mention, there is an even smaller, but non-zero, probability for other storms developing farther west around BTL and AZO in a similar outflow-related fashion. Separate activity over northeast WI could spread southeast into northwest Lower MI after 00Z tonight, but current expectations are for this to remain north of the MKG and GRR terminals. Did include a brief period of MVFR visibility restrictions at all terminals overnight...although MKG could temporarily experience IFR ceilings and JXN could similarly experience a brief period of IFR visibilities. && .MARINE... Issued at 322 AM EDT Wed Jun 19 2024 Surface and buoy obs indicate winds are gusting over 25 knots and waves currently are in the 3-4 foot range; we`ll continue with the Small Craft Advisory and Beach Hazards Statement today. Wind will decrease as the day progresses and the pressure gradient slackens. After today, we`ll see several days where wind and waves will not be hazardous to boaters or beach goers. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement until 4 PM EDT this afternoon for MIZ037- 043-050. Heat Advisory until 8 PM EDT Friday for MIZ043>046-050>052- 056>059-064>067-071>074. Air Quality Alert until midnight EDT tonight for MIZ050-056-057- 064-071. MARINE...Small Craft Advisory until 4 PM EDT this afternoon for LMZ847>849. && $$ UPDATE...MJS DISCUSSION...Meade/TJT AVIATION...TJT MARINE...04