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Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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731 FXUS63 KGRR 140754 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 353 AM EDT Sun Jul 14 2024 .KEY MESSAGES... - Showers and storms through this morning - Severe weather possible late Monday and Monday evening - A few showers and storms still possible Tue and Wed - Dry and pleasant weather Thursday through Sunday && .DISCUSSION... Issued at 353 AM EDT Sun Jul 14 2024 - Showers and storms through this morning We are starting out this morning with a MCS that is steadily weakening as it moves through the area. The line of storms had gusts to 30-35 mph as it moved onshore, and has only weakened to just mainly showers and embedded storms as of 330 am this morning. The most impressive aspect of this is the MCV that is well defined over Muskegon and Newaygo counties. Thankfully there are no known impacts with this like a wake low wind event, or anything else. This whole complex will continue to weaken as it does not have deep and rich moisture available ahead of it. The next feature we are watching is the thunderstorm complex near the MN and WI border as of 330 am this morning. This complex has developed at the nose of a weak secondary low level jet feature behind the first complex from earlier. Lots of instability out there, and it doesn`t take much to fire something off. The expectation with this is that we will likely see showers and storms for at least the western half of the CWFA by mid-morning. After that, it will likely weaken and shift south and east by late this afternoon. Severe weather possibilities with this next complex look fairly low. Anything that is a bit stronger will likely stay west of the area as it follows the axis of the best instability gradient. One thing that we will watch is for the possibility of training storms that could lead to some minor flooding. We have a very moist air mass in place, and rainfall will be fairly efficient. It does seem that once the second batch moves through, the threat for organized convection for tonight and early Monday will be quite limited. A few storms could form for southern areas that might not experience the storms later this morning, and with some untapped instability would be present. This would most likely happen in the late afternoon and evening hours. Then being in between features and during the min in instability overnight, most areas would be rather quiet and just warm and humid. - Severe weather possible late Monday and Monday evening The quiet weather will linger into the first portion of Monday, before things could get quite active Monday afternoon and evening. The lack of activity Monday morning will allow for the atmsophere to destabilize well with at least some sunshine, and the warm and humid air mass remaining in place. Temperatures are forecast to warm to around 90 and dew points will be in the low to mid 70s. This will drive heat indices up to the upper 90s across the south, and slightly cooler further north. Right now with our expected temps and dew points, we think we will be just short of Heat Advisory criteria, and will hold off for now. We will see a couple of short waves approach later on Monday, and an associated cold front that will be poised to push through a bit later. Forecast CAPE`s are expected to increase to almost 4,000 J/kg by early Monday evening. The atmosphere will be mainly capped for much of the day. The short waves and cold front will likely provide enough forcing to go along with some weakening of the cap to fire convection. Once convection does fire, severe weather is very plausible across the entire area, with all hazards in play. Deep layer shear values are forecast to be around 40 knots. We will have a fairly strong low level jet pushing in that will provide for plenty of low level shear. The degree of instability, thick CAPE profiles aloft, and mid level lapse rates 6.5 to 7.5C/km will all bring the large hail threat. The wind threat will develop as the storms develop their cold pool and 40-50 knots in the mid levels help out. A tornado threat will also exist due to the strong low level shear with the low level jet. SRH`s are forecast to increase to 200 by 00z Tue, with 0-1km shear values of 25-30 knots, and 0-3km values of 35 knots. The hodograph has some nice curvature in the lowest levels with the directional and magnitude shear in the lower levels. This will linger through the evening, until the front can pass south of the area overnight. Any training of these storms in this high moisture environment could also cause some flooding. - A few showers and storms still possible Tue and Wed A shower and tstm risk may still exist on Tuesday, mainly south and east of GRR, before the cold front completely clears the area. Cooler and drier air arrives behind the cold front for Wednesday but the upper trough will be digging in with a decent shortwave arriving at peak heating. That will support another chance of showers and storms, although relatively limited coverage expected and mostly favoring the Mt Pleasant and Clare areas. - Dry and pleasant weather Thursday through Sunday The Thursday through Sunday period is looking dry with comfortable temperatures and humidity levels as a sprawling area of high pressure impacts the region. Mostly sunny days and clear nights expected with highs near 80 and lows in the 50s. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 157 AM EDT Sun Jul 14 2024 The incoming shower and tstm activity has been weakening but we may still have some brief MVFR/IFR vsbys in any of the heavier rain showers over the next few hours. The thunder risk looks to be restricted to areas south of I-96. After the current activity passes through/wanes, attention turns to the storms currently near MSP. These storms should be arriving in west Michigan toward daybreak and may produce IFR vsbys in heavy rainfall through Noon before diminishing/exiting this afternoon. Most of this afternoon currently looks dry/VFR however additional storms are possible after 00Z MON. Was not confident enough to include thunder in the tail end of the TAF period of Sunday evening but this is something to watch going forward. && .MARINE... Issued at 353 AM EDT Sun Jul 14 2024 We do not anticipate any headlines being needed through today for marine interests. There will be an increase in wind ahead of the stronger front later Monday, and behind it Monday night into Tuesday. We will continue to evaluate the need for headlines for those times. Not enough confidence to hoist them at this time, plus we are still proably 36 hours away, so there is some time. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Air Quality Alert until midnight EDT tonight for MIZ050-056-057- 064-071. MARINE...None. && $$ DISCUSSION...Meade/NJJ AVIATION...Meade MARINE...NJJ