Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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355 FXUS63 KGRR 220733 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 333 AM EDT Sat Jun 22 2024 .KEY MESSAGES... -Potential severe weather and flooding today/this evening -Dry Monday, strong storms possible Tuesday/Tuesday night -Dry Wednesday/Thursday, storminess returns next weekend && .DISCUSSION... Issued at 332 AM EDT Sat Jun 22 2024 -Potential severe weather and flooding today/this evening A warm front has lifted to the northern cwa early this morning where it`s expected to become quasi stationary today. Low pressure in Nebraska will move ENE toward Wisconsin by this afternoon. A strong southwest flow ahead of the low is helping to bring in moisture-rich air and precipitable water values in excess of 2 inches is expected today. There will be some destabilization ahead of the low across the northern and central cwa today. Thunderstorms will likely spread east from Wisconsin. CAPE values are not particularly impressive. However, shear values increase to 45 knots this afternoon. An impressive LLJ is progd to move toward the northwest CWA this afternoon. A weak short wave aloft will aid in convective generation. It`s possible that as the shear increases we could see some low topped supercells develop. Impressive helicity values around 400 m2/s2 move over the northern rows this afternoon near the frontal boundary. It`s not out of the question a tornado or two could spin up along the boundary. As the low crosses northern Lower around 00z, the trailing cold front will begin to move south. Showers/storms will form along the cold front and move across the rest of the cwa during the evening and overnight. Areas south of I-96 will likely see a bit more destabilization today due to a bit more sunshine. And so any storms that form along the cold front will be able to tap into that instability. Strong wind gusts and torrential rainfall will be the main threats. Precipitation will be ending by Sunday morning. Today will be the last day of the Heat Advisory. Heat indices will top out in the mid 90s again today. A cold front will move across the state tonight leading to highs in the 75 to 80 degree range Sunday. -Dry Monday; strong storms possible Tuesday/Tuesday night Monday will feature sunshine and comfortable temps/humidity with surface ridging in control before a warm front returns on Tuesday and sends back the heat and humidity for a day. GFS has SB Capes exceeding 3000 J/KG Tuesday afternoon once the warm sector arrives, setting the stage for the possibility of some stronger storms by evening as a cold front and H5 shortwave trough approach from the northwest. -Dry Wednesday/Thursday; storminess returns next weekend The cold front exits early Wednesday and we dry out by afternoon as cooler/drier air arrives from the north. High pressure settles in for Thursday with dry weather still prevailing, but then models diverge which leads to low confidence timing the return of our next chance of showers and storms. The more progressive GFS has rain chances returning already on Friday whereas ECMWF holds off until Saturday. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 205 AM EDT Sat Jun 22 2024 The cluster of showers and storms currently over srn WI and nrn IL extrapolates northeast into MKG around 11-12Z and should last on and off through much of Saturday morning. These may impact GRR as well although probably to a lesser extent than MKG. Ocnl MVFR/IFR possible as these storms pass through. After the morning convection it looks like the MKG/GRR terminals may dry out and go predominantly VFR for this afternoon before more showers and storms return after 00Z this evening. Otherwise VFR weather prevailing all day for the terminals south and east of GRR with the bulk of the rain and tstms remaining off to the north over central and nrn Lwr MI. The potential for showers and storms does not really ramp up across this area until after about 02-03Z tonight. Winds increasing to 12-22 kts out of the southwest by Noon today. && .MARINE... Issued at 332 AM EDT Sat Jun 22 2024 Wind and waves will increase behind a cold front tonight necessitating a Small Craft Advisory and Beach Hazards statement south of Grand Haven. Wind and waves will decrease late tonight. Additionally, thunderstorms will pose a threat to boaters and beachgoers today and tonight. && .HYDROLOGY... Issued at 332 AM EDT Sat Jun 22 2024 Very juicy air with precipitable water values north of 2 inches are expected across the cwa today. A stationary frontal boundary over the northern cwa will focus showers and thunderstorms today. Any of these storms will be capable of producing torrential rainfall. Training echos will be an issue today and local probability matched mean values hint at the potential for 2 to 4 inches of rain along US-10 in an area that saw locally heavy rainfall from storms yesterday. As a result, we have issued a Flood Watch for the northern 3 rows of counties from noon today through 6 am Sunday. Local flooding of poor drainage areas is possible. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Flood Watch from noon EDT today through late tonight for MIZ037>040-043>046-050>052. Heat Advisory until 8 PM EDT this evening for MIZ056-057-064>067- 071>074. Beach Hazards Statement from this evening through Sunday morning for MIZ056-064-071. MARINE...Small Craft Advisory from 8 PM this evening to 8 AM EDT Sunday for LMZ844>846. && $$ DISCUSSION...Meade/04 AVIATION...Meade MARINE...04 HYDROLOGY...04