Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 251105

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
705 AM EDT WED MAY 25 2016


VFR in a mix of mid and high clouds during the morning will precede
a cold front settling into the area from northern lower Michigan.
This front is expected to stall between MBS and FNT during early
afternoon and provide a focus for scattered showers and
thunderstorms from about mid afternoon through evening having the
best chance to affect MBS mid to late afternoon. Conditions will
otherwise remain VFR around SE Michigan even within the frontal zone
outside of the scattered heavier showers/storms. MVFR is then
expected to develop as coverage of showers increases and as boundary
layer moisture pools enough for development of fog and/or lower
ceiling through sunrise Thursday.

FOR DTW...VFR will consist of some cirrostratus during the morning
that will thin in favor of scattered high based cumulus during the
afternoon. Showers/storms will remain outside of the DTW/D21
airspace until tonight, and especially after midnight through mid
Thursday morning. At this time, plan to hold off on TSRA mention for
tonight until timing can be refined more precisely.

//DTW Threshold Probabilities...

* Low for ceiling 5000 FT or less tonight.

* Moderate for thunderstorms affecting DTW/D21 air space tonight.


Issued at 333 AM EDT Wed May 25 2016


Appears in the long range models that the current western conus
trough and eastern conus ridge will hold through the next week or
more. This means the current warm airmass will hold in place with
high temperatures largely in the 80s through the forecast. It also
means the northeast flow regime will persist with a series of
shortwaves ejecting out of the trough up through the Midwest keeping
chances of thunderstorms in the forecast nearly every day. It won`t
be a complete wash out this week though as best chances of
precipitation will be tied to shortwaves with an overall lack of
lower level lifting mechanisms. One other thing to watch for will be
upstream MCS`s and the potential they can hold together into lower

Currently there is a stalled cold front draped across mid Michigan
which was the focus for some showers and thunderstorms on Tuesday
and Tuesday night. A narrow ribbon of enhanced theta e was co-
located along the front providing a boost in moisture to a
relatively dry column, while weak convergence developed at the
surface at the front. A fairly strong mid level short wave has
lifted out of southern California and will pass through MN and into
Ontario this evening. A lobe of vorticity extending southeast from
the developing mid level low will sweep through southern Michigan
this evening, which will change the stalled front into a warm front
that will lift north toward the straits by early Thursday afternoon.
This will present one of the best opportunities for thunderstorms in
the forecast as the nose of a strong theta e surge lifts into the
area behind the warm front. Elevated levels of CAPE around 500-1000
J/Kg, shear increasing to around 30 knots, and favorable mid level
lapse rates and LI`s will also accompany the front. Some storms
could become strong but stability in the lower levels will keep
things more elevated which could reduce gust potential. Coverage
should increase over the western and northern part of the SE MI but
most locations will have at least a high chance of showers.

Another wave is set eject through the flow Friday morning presenting
the next good chance at widespread showers and thunderstorms across
the area. Upstream trough amplification will lead to the resident
ridge getting pulled back to the west which will pull the better
support westward as well. Will have to watch how this all evolves
moving forward as large convective systems in the plains may keep
the lower heights further south and east.

Heading into the weekend the wave train continues but timing any of
these features is difficult at best with this type of active
pattern. It is worth noting that outside of the two more dominate
waves heading into the weekend, the models are all fairly uniform in
presenting more of a diurnal component to the shower activity. Once
we get the higher dew points into the region, a summer like pattern
will ensue with diurnal heating popping a few showers in the
afternoon. With lack of any focusing mechanism coverage will be ill
defined, hence a daily chance pop lingers in the forecast.


A weak cold front will remain the focal point for marine weather in
the short term as it settles into southern Lake Huron and central
lower Michigan today and then returns northward tonight. The wind
will be light within and around the frontal zone leaving the main
impact to be showers and thunderstorms that will become more
numerous tonight. Fog will also become increasingly prevalent as the
warm and humid air pools over the colder open waters of Lake Huron.

The front will move northward into Canada Thursday and leave light
southerly wind over all marine areas that will maintain warm air
Friday into Saturday. Showers and storms remain possible but will be
less organized until possibly later Saturday and Saturday night as
low pressure develops over the upper Midwest. This system will also
help maintain warm conditions and light south wind well into the
holiday weekend.


Warm air with increasing humidity will pool along a front settling
as far south as the I-69 corridor today. High temperatures returning
to the lower and mid 80s could result in a few thunderstorms along
the front during the afternoon and evening. Showers and storms are
then expected to increase coverage overnight with the help of low
pressure over the Midwest that will pull the front northward
Thursday. Rainfall amounts are expected to vary widely depending on
thunderstorm coverage but should average 0.25 to 0.5 inch for the
Wednesday night-Thursday period with locally higher totals near 1
inch possible in thunderstorms. Warm and humid air will then remain
in place to support shower and thunderstorm potential into the
weekend with less organization until arrival of the next low
pressure system possibly by Saturday into Saturday night.



Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.




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