Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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639
FXUS63 KDTX 250733
AFDDTX

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

.DISCUSSION...

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
Michigan.

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.

&&

.MARINE...

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.

&&

.HYDROLOGY...

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.

&&

.PREV DISCUSSION...
Issued at 1155 PM EDT Tue May 24 2016

AVIATION...

Persistently dry/stable low level environment will sustain a clear
sky within the lowest 5000 ft tonight and early Wednesday. Modest
southwesterly flow during this time as dominant high pressure of
recent days gradually pulls east.  Weakening frontal boundary will
slide into central lower MI during the early morning period. This
may support some widely scattered high based showers in the vicinity
of MBS. Gradual increase in moisture Wednesday may allow for a low
coverage of late day VFR cumulus.  Prospects for thunderstorm
development through Wednesday evening remain too low to include at
this time.

//DTW Threshold Probabilities...

* None


&&

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

$$

DISCUSSION...DRK
MARINE.......BT
HYDROLOGY....BT
AVIATION.....MR


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at www.weather.gov/detroit.



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