FXUS63 KDTX 262017

AFDDTX



Area Forecast Discussion

National Weather Service Detroit/Pontiac MI

417 PM EDT Thu Jun 26 2025



.KEY MESSAGES... 



- Scattered to numerous thunderstorms continue this afternoon after

  shifting north toward the I-69 corridor.



- A Marginal Risk of severe storms may lead to damaging down burst

  winds. Localized flooding is also possible due to very moist

  airmass and saturated soils from recent storms this week.



- Yet another round of thunderstorms is likely Friday as a cold front

  moves through Lower Michigan. There is a Marginal Risk of severe

  intensity during the afternoon and evening.



- High temperatures increase back to the upper 80s to 90 degrees

  Friday and Sunday after a brief cool down Saturday.



&&



.DISCUSSION...



An interesting progression of thunderstorm development from this 

morning continues to unfold across the area this afternoon and 

evening. Broad scale support for nocturnal/elevated convection late 

last night resulted in storms grazing the Tri Cities and Thumb 

around sunrise this morning. The larger scale support, mainly near 

the entrance region upper jet circulation, helped the 850-700 mb 

theta-e ridge percolate over southern Lower Mi all morning until 

becoming surface based toward noon. A messy multicell convective 

mode dominated since then and which has migrated south of the Ohio 

border after forecast issuance. Lingering severe potential, for 

mainly damaging wind and heavy rainfall, has shifted farther north 

to the hybrid marine layer/surface front. This has released new 

storms where MLCAPE projections show a 2000 J/kg instability axis 

through early evening. In all cases, precip loaded damaging wind 

gusts are the primary severe hazard followed by heavy rainfall. Hail 

is a distant third given the deep moisture profile and low CAPE 

density in the mid levels. 



The ongoing storms across Lower Mi are expected to dissipate with 

the loss of heating tonight, in time to look toward the Midwest 

where another low pressure system is interacting with the resident 

surface front across the Great Lakes. Surface based storms out there 

are also expected to diminish/dissipate on the downward side of the 

heating cycle followed by a new transition to low level jet forced 

convection tonight. The surface low moves into NW WI while pulling 

the front back north into northern Lower Mi late tonight and Friday 

morning. This presents a dry warm sector scenario for SE Mi and a 

more favored nocturnal MCS track north of the Tri Cities late 

tonight into Friday morning.



Yet another round of thunderstorms is likely for SE Mi Friday 

afternoon as the WI surface low continues into northern Ontario 

while dragging a cold front across Lower Mi. The solid warm sector 

in place over the area is HREF projected to build SBCAPE up to 

around 2000 J/kg ahead of the front. Bulk shear is also advertised 

to be on the low side, however a deeper dive into model soundings 

indicates unidirectional mid level flow around 35 knots with some 

dry air around the 500 mb level. The big CAPE helps with the lower 

end wind field for storms evolving into line segments along the 

front with damaging wind potential the primary hazard, as good or 

better than SPC's Marginal Day 2 outlook for our area into Friday 

evening. 



The Friday cold front ushers weak high pressure into the area for 

Saturday, slightly cooler and a little less humid. This reverses 

Sunday as the next low pressure system moves into the Great Lakes 

and brings highs back up near 90. The front associated with this 

system leads to a larger scale pattern shift resulting in at least 

lower humidity with greater staying power next week.



&&



.MARINE...



Marine conditions remain unsettled in terms of thunderstorms this 

afternoon through Friday while wind and waves are otherwise subdued 

outside of the storms during this time. The current center of low 

pressure in the Midwest moves eastward along a frontal zone that has 

been wavering across Lake Huron and Lower Michigan over the last 

couple days. The low moves across the Straits Friday and pulls a 

weak cold front southward through Lower Michigan and into the Ohio 

valley Friday night. Light wind and favorable weather follow with 

weak high pressure Saturday followed by another low pressure system 

entering the northern Great Lakes during Sunday through Sunday 

night. This system brings a stronger cold front into Lake Huron and 

Lower Michigan to start next week.



&&



.PREV DISCUSSION...

Issued at 125 PM EDT Thu Jun 26 2025



AVIATION...



Moderately unstable, uncapped environment over southeast Michigan, 

with frontal boundary/dew pt gradient near the I-69 corridor. 

Disorganized strong thunderstorms should continue, but location is a 

bit challenging as outflow boundaries serve to focus additional 

redevelopment.  None-the-less, multiple rounds of showers/storms 

across southern TAF sites looks reasonable, and will be maintaining 

the tempo TS group through the afternoon, although concerned with 

the latest drift to the south with the bulk of the activity.

As low pressure enters the Western Great Lakes this evening, the 

surface boundary over Lower Michigan will attempt to lift north, 

providing better focus over MBS/FNT for the evening hours. With the 

elevated low level moisture/high surface dew pts over southeast 

Michigan tonight, much better chance for low clouds and/or some fog,

depending on how thick mid/high clouds from upstream activity over 

the Western Great Lakes advances east. However, with today's 

rainfall, enough confidence in MVFR stratus and/or fog development to

include in tafs, with very light southerly winds tonight, IFR not 

out of the question, especially at MBS. Another round of showers and

thunderstorms appears likely tomorrow afternoon as cold front 

arrives during peak heating. Southwest wind gusts ahead of the front

will likely reach into the 20-25 knot range in the afternoon, in 

addition to the stronger/gustier winds in any thunderstorm. 



For DTW/D21 Convection...Bulk of storms over southern Lower Michigan 

are showing signs of propagating southeast, away from terminal. Thus

lower confidence for the rest of the afternoon. None-the-less, would

expect enough destabilization to trigger additional storms late this

afternoon, and will keep much of the inherited taf intact. 



 THRESHOLD PROBABILITIES...



* Low to medium for thunderstorms this afternoon and evening.



* Low in ceilings aob 5000 feet through evening. Moderate overnight 

  and tomorrow afternoon.





&&



.DTX WATCHES/WARNINGS/ADVISORIES...



MI...None.

Lake Huron...None.

Lake St Clair...None.

Michigan waters of Lake Erie...None.



&&



$$



DISCUSSION...BT

MARINE.......BT

AVIATION.....SF





You can obtain your latest National Weather Service forecasts online

at www.weather.gov/detroit.

