Marine Forecasts

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7 Day Forecast for Marine Location Near Forestville, MI

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Area Discussion for - Detroit/Pontiac, MI

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FXUS63 KDTX 071808 AFDDTX

Area Forecast Discussion National Weather Service Detroit/Pontiac MI 208 PM EDT Tue Apr 7 2020

AVIATION.

Warm front/moist boundary layer now starting to push north of the Metro terminals with wind direction veering from southeast to southwest, which will allow cigs to lift out of IFR cigs. Diurnal response to clearing trends have allowed MVFR stratocu to develop upstream which will spread across the Metro terminals north up into KPTK this afternoon, with periods of VFR possible as dry air advects into the region. Better moisture resides across KFNT into KMBS which will have better odds to hold onto MVFR stratus through the afternoon. Otherwise, attention will turn to tonight's cold front which is expected to produce likely thunderstorms, some strong, across the SE MI, centered between 00Z-04Z. Stronger storms will have the potential to produce damaging wind gusts and large hail along with a quick veering in wind direction to the northwest associated with the gust front of approaching storms which could cause brief crosswind concerns. Otherwise, passage of the cold front will maintain MVFR cigs and possibly IFR cigs overnight, and although post-frontal wind gust potential is not too impressive, gusts to 20 knots will be possible overnight. Clear trend then expected later in the day on Wednesday.

For DTW . MVFR cig trends this afternoon, with possible periods of VFR, before a strong cold front brings likely potential to see thunderstorms, some strong. Thunderstorm potential has been narrowed down to 02Z-04Z for the terminal, where wind gusts to or above 40 knots along with large hail will be possible. Additionally, gust front associated with any linear/bowing storm segments will have the potential to quickly veer wind direction to the northwest, posing brief crosswind concerns with any thunderstorm potential.

DTW THRESHOLD PROBABILITIES .

* Moderate for ceiling 5 kft or less this afternoon. Periods of VFR possible.

* High for thunderstorms tonight between 02-04Z.

PREV DISCUSSION. Issued at 1145 AM EDT Tue Apr 7 2020

UPDATE .

The earlier forecast update reflected the trend for showers to expand across the Thumb region during the morning within the northern reaches of the elevated warm front. These track into Lake Huron as the 850-700 mb theta-e gradient migrates northward during the afternoon. Isolated pockets of stronger convection occurred in the Detroit area, still elevated north of the surface front near the Ohio border, but near the edge of steeper mid level lapse rate. The more intense updrafts quickly became organized within the more strongly sheared mid level wind field resulting in some pea size hail in any cells that had lightning. This activity also exits eastward leaving most of the afternoon with lower or no coverage as convection transitions from elevated to upstream surface based. Upper level support expected to help with late afternoon and evening initiation has convection ongoing over Wisconsin possibly offering at least some hints at hail potential in our area this evening. Severe potential remains solidly in line with the SPC outlook for Lower Michigan.

PREV DISCUSSION . Issued at 352 AM EDT Tue Apr 7 2020

DISCUSSION .

Zone of warm air advection at 850-925 mb manifesting from a modest increase in low level southwest flow will make steady inroads into southern sections of lower Michigan through the morning period. Weak shortwave energy lifting through the advancing warm frontal zone will act to engage the underlying isentropic ascent and theta-e advection to maintain the potential for shower production during this time - mainly south of the M-59 corridor. Perhaps just enough mid level destabilization to offer an isolated thunderstorm near the Ohio border. Meaningful ascent and deeper mid level moisture sweeps east by early afternoon, leaving the mid level profile increasingly capped as a defined elevated mixed layer takes residence. Afternoon conditions then simply defined by the lingering low level moisture maintained under weak warm air advection as the warm frontal slope noses deeper into the area with time. This ensures extensive stratus, while limiting the prospects for renewed precip development for the latter half of the day. Lack of insolation potential means more reliance on the advective process in establishing late day or evening highs. Low level flow veered just enough north of the surface front to suggest the boundary could make greater inroads, affording a corresponding better diurnal response despite the cloud canopy. Outgoing forecast maintains a broader distribution in highs from mid 60s near the Ohio border to mid 50s across the eastern thumb.

Stronger shortwave energy tied to a narrow upper jet streak will track across lower Michigan early tonight. While greater mid level dynamics will tend to remain north of the area, an associated surface reflection and trailing cold frontal boundary will translate east-southeast across southeast Michigan during this time. Ensuing increase in convective potential - likely initiating just upstream - during the evening hours as this forcing engages the steeper mid level lapse environment residing above the eml and capitalizes on a gradually destabilizing low level profile as the warm sector works deeper into the state. Magnitude of the deep layer shear certainly supportive of organized discrete and/or multicell structures, presenting a solid case for possible large hail development all locations given the mid level parameters. Damaging wind gust threat ultimately defined by the degree of near surface destabilization, greater prospects inherently planted with southward extent. Recent CAMs guidance suggest at least a weakly unstable pre-frontal boundary layer will emerge - MLCAPE 500-700 j/kg. While the underlying environment does offer an isolated tornado risk as well, inbound convection will largely encounter an already veered low level wind field except at the warm frontal interface. Main window for possible severe convection centered 8 pm to Midnight.

Any lingering early day cloud trending toward full sun Wednesday, under strong post-frontal dry air advection and increasing mid level subsidence. Any brief intrusion of cooler air quickly eliminated under modest diurnal mixing in full isolation. One final day of above normal warmth results.

Strong pv anomaly progged to descend across the great lakes will initiate a firm pattern change toward colder conditions during the late week period. Pronounced height falls on the lead edge will drive the strong attendant cold front through Wednesday night. Pronounced low level convergence backed by increasing mid level ascent will anchor a linear axis of rainfall on the inbound sfc to 850 mb frontal slope. The ensuing isentropic descent under increasing cold air advection will then bring a period of gusty west- northwest winds in the immediate wake of the front during the early morning hours. Projected magnitude of winds within the mixed layer would support a brief pop in gusts of 30 to 40 mph.

Unsettled conditions exist Thursday within a cold and moist cyclonic flow. This means extensive stratocumulus with the potential for some diurnally augmented showers. Firm northwest winds throughout the day, with a deepening mixed layer contributing a strong gust component. Ceiling on peak gusts perhaps near advisory criteria /45 mph/, but with strong dependence on scope of cloud cover and resulting degree of mixing. The resident cold conditions then locked in for the foreseeable future.

MARINE .

Lighter southeasterly winds will continue through the evening as high pressure pushes off to the east. Moisture will be on the increase through the overnight hours as low pressure progresses into the region. Expect limited winds and wave action with chances for a few showers overnight. A more concentrated area of showers with some occasional thunder will lift through Tuesday evening. Large- scale surface pressure field will remain largely unperturbed from this disturbance as winds hold in the 10-15 knot range in the southeast quadrant. High pressure temporarily builds in from the Plains on Wednesday before additional wet weather arrives Wednesday night. This will force stronger winds on Thursday with 30+ knot gusts tied to a strong low-level wind field once mixing gets underway Thursday afternoon.

HYDROLOGY .

Multiple rounds of showers are expected to lift across Southeast Michigan through Wednesday night, particularly during the overnight hours. The first round tracks through during the early to mid morning hours today, mainly across areas generally south of the M-59 corridor. Highest rainfall totals expected near the Ohio border, where amounts upward of .3" will be possible. Potential for more a widespread area of rain, along with thunderstorms, exists tonight. Once again, rainfall totals generally around at or below a quarter of an inch, although some localized higher amounts are possible within any thunderstorms. A final round of rainfall accompanying a cold front Wednesday night appears quick hitting, currently favoring amounts below one quarter inch. All told, these amounts are not expected to contribute to flooding concerns.

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

AVIATION . AM UPDATE . BT DISCUSSION . MR MARINE . SP HYDROLOGY . MR

You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.

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Weather Reporting Stations

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Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	Pressure	DewPt
HRBM4 - 9075014 - Harbor Beach, MI	48 mi	59 min	SSE 11 G 13	42°F	46°F		1008.3 hPa	38°F
FTGM4 - 9014098 - Fort Gratiot, MI	62 mi	59 min	SE 4.1 G 6	44°F			1009.2 hPa	41°F
MBRM4 - 9014090 - Mouth of the Black River, MI	64 mi	59 min		44°F			1009.3 hPa

Wind History for Harbor Beach, MI

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Airport Reports

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Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Port Hope, MI	59 mi	50 min	S 10 G 17	mi		48°F	39°F	71%	1008.7 hPa

Link to 5 minute data for KP58

Wind History from P58 (wind in knots)

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S10 G17

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Tide / Current Tables for

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Tide / Current Tables for

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Weather Map

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Wind Forecast for Detroit/Pontiac, MI (14,3,4,5)

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Ground Weather Radar Station Detroit, MI

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