Sunrise 6:04 AM   Sunset 9:00 PM Moonrise 4:14 PM   Moonset 3:10 AM

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LHZ422 Inner Saginaw Bay Sw Of Point Au Gres To Bay Port Mi- 407 Am Edt Sun May 19 2024
Today - South winds 10 to 15 knots becoming southwest 5 to 10 knots late in the morning, then becoming southeast 10 to 15 knots early in the afternoon backing to the east late in the afternoon. Partly cloudy in the morning then clearing. Waves 2 feet or less. Tonight - Northeast winds 10 to 15 knots becoming east 5 to 10 knots after midnight. Mostly clear. Waves 2 feet or less. Monday - Southeast winds 5 to 10 knots becoming south 10 to 15 knots early in the afternoon. Mostly Sunny in the morning, then partly cloudy with a chance of Thunderstorms in the afternoon. Waves 2 feet or less. Monday night - South winds 10 to 15 knots. Partly cloudy in the evening becoming mostly cloudy. A chance of showers and Thunderstorms. Waves 2 feet or less.
see lake huron open lake forecast for days 3 through 5.

LHZ400
No data

FXUS63 KDTX 190757 AFDDTX

Area Forecast Discussion National Weather Service Detroit/Pontiac MI 357 AM EDT Sun May 19 2024

KEY MESSAGES

- Warm and muggy conditions are expected today and during the early part of the week with daytime highs in the 80s.

- Showers and thunderstorms are likely this afternoon from Port Huron southwestward to Adrian including Metro Detroit. Brief heavy downpours and gusty winds are the main concerns this afternoon.

- Chances exist for thunderstorms Monday afternoon mainly north of I 69. There will be a potential for strong to severe thunderstorms, but low confidence exists with exactly the strong to severe threat will occur.

- A much less humid airmass is expected for the end of the week.

DISCUSSION

A dynamic upper level jet streak is forecasted to broaden today while lifting to Hudson Bay. The broadening will force geopotential heights to flatten across Lower Michigan which will not only allow a surface cold front to settle southward through northern Lower Michigan but also result in increasing boundary layer warming immediately ahead of the approaching cold front. A notable but narrowing thetae plume is expected to be in place during peak heating this afternoon with forecast soundings supporting a well mixed boundary layer of upwards to 4.0 to 6.0 kft agl. An interesting scenario for this afternoon as a strong consensus of hiresolution models support convection over the southeastern 2/3rds of the cwa. This is despite fairly convincing background anticyclonic vorticity advection over all of the forecast area and a resolved weak 700mb anticyclonic circulation pushing overhead. At first glance of the environmental wind profile, cell movement would appear to be light west to east. However, the strong consensus in convection this afternoon is unanimous in a slow northeast to southwest track that is in agreement with the backward propagating Corfidi vectors.

Based on the model support, increased PoPs into the likely-numerous category for the afternoon in southeast sections of the forecast area. Trigger/lifting mechanisms are expected to be near the shorelines where increased convergence is located due to differential heating. Do not really see a true lake breeze signal per se, but convection will likely behave similarly with the backbuilding and convective reinforced outflow. Very little to no shear suggest no strong or severe thunderstorm risk. The main threat with the convection will be heavy rainfall due to slow storm movement. Precipitable water of 1.3 inches and flow aligned along the axes of lift increases the concern. Will forgo any thoughts of a Flood Watch due to an extremely small footprint to any modeled convective cells and a favorable setup for anticyclonic vorticity advection. Gusty winds due to pulse type-water loading and small hail (Surface based CAPE in excess of 1000 J/kg) will be possible.

An upper level trough pushing into the Pacific Northwest will cause downstream amplification to a ridge over the central United States Monday and Tuesday. The cold front that approaches the area today will quickly lift northeastward on Monday. Some uncertainty exists with the Monday afternoon forecast as trends suggest upstream convective activity from the Plains will approach northern Lower Michigan Monday afternoon. Convective parameters are in the ballpark to support a threat of severe weather. Mixed Layer CAPE is forecasted to reach and exceed 1750 J/kg and 0-6km bulk shear will possibly reach/exceed 35 knots. While the magnitude of the bulk shear suggests some potential for mesocyclones, the morphology of the cam output suggests convective line with possible forward propagating characteristics. The severe threat will likely hinge on the track of convective vorticity which points to northern Lower Michigan. Will need to monitor trends in future model data as SPC has included Southeast Michigan in a Marginal risk for severe weather. The majority of the models are dry here for Metro Detroit but many including the latest ECMWF are bullish on late afternoon convective activity near Saginaw Bay and Lake Huron. Expect revisions to the convective Outlooks. Southeast Michigan will be well within the warm sector with an unstable air mass and highs on Monday expected to again reach the middle 80s. The inherited forecast included a range of slight chance to chance for the northern forecast area.

Uncertainty continues into Tuesday as convectively augmented vorticity maxima will have the potential to stream out of the trough toward Southeast Michigan. A dynamic low pressure system is progged to wrap up over the northern Mississippi River Valley Tuesday with background forcing downstream again supporting large scale subsidence over Lower Michigan. Confidence is not particularly high given the favorable conditions for convection across the Plains, but there is a signal for Tuesday morning activity then pushing out and drying for the afternoon. Confidence is then reasonably high for a cold front pushing through the area early Wednesday. Drying with dewpoints falling into the 40s is expected to carry out the remainder of the week.

MARINE

Humid conditions persist with pockets of fog across the region this morning. Fog should largely dissipate from Lake Huron early this morning as southerly flow increases ahead of a cold front.
Meanwhile, fog expands across western Lake Erie and possibly into Lake St. Clair as light southeast wind persists there. This should mix out by midday. Today's cold front will be weak but may produce isolated showers or thunderstorms this afternoon and evening, especially along the nearshore waters. An area of low pressure then tracks in from the Midwest late Monday into Tuesday, bringing the next chance for showers and storms with the highest likelihood across northern Lake Huron. Winds and waves are expected to remain below Small Craft Advisory criteria outside of any localized higher winds within any thunderstorms. A period of stronger south wind is increasingly likely late Tuesday night into Wednesday as a stronger low and associated cold front lift into the region.

PREV DISCUSSION
Issued at 1154 PM EDT Sat May 18 2024

AVIATION...

Will maintain a mention of fog KYIP/KDTW/KDET within light southeast flow from Lake Erie, but will temper the degree of lower stratus as late evening satellite trends do not support much stratus at this point. Winds veer to the southwest and then west as a weak frontal boundary settles into the area. This front, combined with a number of lake breeze boundary, will be the focus for widely scattered to scattered showers/thunderstorms late in the day, mainly KPTK south.
Wind will shift to northeast tomorrow night behind the front and then basically become light/variable.

For DTW/D21 Convection...There will be a chance for scattered thunderstorms Sunday afternoon as a weak frontal boundary interacts with lake breeze(s) serving as the focus. Isolated heavy downpours may bring visibility restrictions.

DTW THRESHOLD PROBABILITIES...

* Low for ceilings aob 5kft late tonight.

* Low for thunderstorms Sunday afternoon.



DTX WATCHES/WARNINGS/ADVISORIES
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.

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