Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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895 FXUS63 KGRR 180155 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 955 PM EDT Fri May 17 2024 .KEY MESSAGES... - Summerlike Weekend - Low Chance for Rain Sunday - Active Early to Mid-Week Period - Cooler End of the Week && .UPDATE... Issued at 955 PM EDT Fri May 17 2024 High pressure situated across the area this evening will bring quiet weather now that the afternoon/evening convection is diurnally fading. We are not expecting much more than an isolated showers near Highway 127 for another hour or so. The main concern tonight is the extent of stratus and fog. Fog remains in place over much of eastern Lake Michigan along our shoreline. This fog will likely begin to spill inland overnight as there will be an increase in southwest flow. Areas of fog are certainly expected tonight with dense fog possible, especially towards Lake Michigan. Going forecast had things well in hand, so no real changes were made. && .DISCUSSION... Issued at 340 PM EDT Fri May 17 2024 - Summerlike Weekend Isolated/pulsing convection continuing through sunset in pattern resembling mid-summer more than spring, featuring a weakly sheared environment with respectable SB Capes of around 1500 J/KG. Diurnally-peaking, random pop-up showers and storms will tend to favor low level convergence zones and current radar/satellite shows one such zone extending from AZO to MBS. Some of these could contain small hail and briefly intense downpours though mid evening per recent radar trends. Once diurnal clouds/convection fade after sunset, patchy fog/stratus is a good bet again tonight given elevated dew pts and light winds. Locally dense fog is possible, especially near Lk MI and in spots where any locally heavy downpours occur today. Diurnal pop-up convection less likely on Saturday due to rising heights and general subsidence pattern with sfc high in place. Very summerlike start to the weekend after fog/stratus burns off with highs in the lower 80s inland from Lk MI. There is a small chance of showers/storms late Saturday night north and west of GRR, related to a weakening band of convection moving southeast from WI. Highs Sunday reaching the mid 80s which is more than 10 degrees above normal. - Low Chance for Rain Sunday Dry conditions carry into Sunday morning, then a weak front moving across northern Michigan will sweep through the area acting as a trigger point for showers Sunday afternoon. Limited moisture leads to only a slight chance for precipitation, but widely scattered showers or storms look possible. - Active Early to Mid-Week Period Better chances for precipitation are expected for the start of the work week as a stronger upper level trough becomes established to our west. Moisture advects into the region while several shortwaves ride the larger upper level trough through the region. While showers and storms are possible Monday, the better environment for storms is expected Tuesday. A deepening surface low will move northeast from the Southern Plains into Wisconsin with a trailing cold front sweeping through the state. Ahead of that front, Michigan will sit in the warm sector with a moist and very unstable atmosphere. Shear will also be plentiful as a low level Jet noses into region Tuesday evening. Uncertainty remains, but Tuesday will be a day to monitor the thunderstorm activity and possible severe weather. - Cooler End of the Week Following the passage of the cold front Tuesday temperatures turn colder to end the week. Uncertainty on how cool we`ll get increases the latter half of the week, but the general idea centers around upper troughing settling over the region with an 850mb thermal trough driving down into Michigan. Current forecast expects peak temperatures a touch below normal (normal highs are around 70 degrees) in the upper 60s to near 70. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 651 PM EDT Fri May 17 2024 No significant changes in the outgoing forecast. Scattered showers,and isolated thunderstorms containing heavy rain, will continue through sunset with coverage to low to put in the TAFs with this package. MKG presently has fog nearby due to dense fog over the lake. While occasional drops to IFR are possible this evening, confidence in when are to low to justify a TEMPO group so have elected to keep just VCFG. After 06z, fog becomes more widespread with MKG and JXN expected to reach LIFR, GRR and LAN IFR, and AZO and BTL MVFR. Fog will dissipate after sunrise tomorrow with VFR conditions persisting after dissipation through the end of the TAF window. West winds of 5-10 knots this evening become light to calm tonight before becoming southwest at 5-10 knots tomorrow. && .MARINE... Issued at 340 PM EDT Fri May 17 2024 Fog has been plaguing much of the cool nearshore waters today and while marine fog trends are very difficult to forecast, current model guidance suggests it will stick around in one form or another through at least Saturday morning. Have therefore extended/expanded the Marine Dense Fog Advisory through Noon Saturday. Otherwise winds/waves staying well below Small Craft Advisory levels through the weekend. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Air Quality Alert until midnight EDT Saturday night for MIZ050- 056-057-064-071. MARINE...Dense Fog Advisory until noon EDT Saturday for LMZ844>849. && $$ UPDATE...Duke DISCUSSION...Meade/Thielke AVIATION...Thomas MARINE...Meade