Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 222310
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
710 PM EDT FRI JUL 22 2016

.AVIATION...

The sky will clear from just a few patches of cumulus post peak
heating. These clouds lingered in the hot/humid air south of the
weak front/moisture boundary lying through central lower Michigan.
There will be no restrictions as this boundary takes most of the
night to settle through SE Michigan and as weak high pressure
follows from the upper Midwest. VFR will then continue through
Saturday with light and variable to light northwest wind becoming
light northeast as the surface high slides eastward Saturday
evening.

For DTW... Favorable operational conditions will be in place tonight
through Saturday. Wind will be light westerly to light and variable
under clear sky through Saturday morning.

//DTW Threshold Probabilities...

* none

&&

.PREV DISCUSSION...
Issued at 339 PM EDT Fri Jul 22 2016

Discussion...

The dewpoint has fallen into the 50s in Huron County on a light west
wind, well ahead of the approaching moisture boundary.
Downsloping off the glacial ridge appears to be the only
explanation. Regardless, the heat advisory is dropped for Huron as
dewpoint front will be arriving shortly anyway.

Veering deep layer flow and weak height falls as a shortwave tracks
northeast of the Great Lakes region is modeled to shunt this
boundary about halfway through the CWA overnight. Upper 50s or low
60s dewpoints will dominate across the north. Southward progress
will slow upon the departure of height falls. However, second and
stronger wave presently over Manitoba will sweep east taking roughly
the same road within the mean flow and kick the boundary safely out
of the area by around sunrise. Low 60s (or lower) Tds areawide by
midmorning, with the exception of the immediate Ohio border where
some of the guidance is allowing 70s dewpoints to creep back in
during the day. Very dry airmass beneath strong subsidence will set
the stage for a clear and hot day as the NAM indicates dry adiabatic
mixing to 750mb. The only thing preventing area wide mid/upper 90s
will be the lake aggregate high present under weak gradient
conditions. An easterly gradient, lake breeze, or a combination of
both will spread into the area during the afternoon confining highs
to around 90 north of I-69. Locations south of M-59, aside from
higher elevations, should easily reach the mid 90s. The heat
advisory will not be extended due to the low humidity as well as the
opportunity for relief tonight as dewpoints fall.

Sunday`s forecast is lower confidence. The trough over the Pacific
Northwest will eject east northeast as it tracks toward Hudson Bay
by Sunday night. Emerging low-level jet over the northern plains
will likely foster thunderstorms/possible MCS over the Dakotas/Upper
MS valley Saturday into Saturday night. The remnants of the MCS and
attendant convectively enhanced wave will wash over the area late
Saturday night and the first half of Sunday. At this time, the
prospects for organized convection locally appears rather poor given
northward displacement of the LLJ and lacking SB instability early
Sunday. The more interesting period will be late Sunday evening into
Sunday night per current NWP timing. Height falls and modest PV
advection juxtaposed with the lower tropospheric warm conveyor
and a moderate wind field could yield convection worthy of keeping
an eye on. Southerly gradient will spell a return to muggy
conditions, but highs on Sunday will be limited to around 90 on
account of cloud cover.

Deeper moisture progged to exit by Monday with drier dewpoints
filtering in as well. Model consensus supports high pressure
building in at the surface and lingering into Wednesday promoting
mainly dry weather. Temperatures will still be above normal with 850
mb temps in the upper teens and guidance indicating highs in the
upper 80s, but not quite as warm as the current airmass. Low
predictability toward the end of next week, but a general trend
toward lowering heights/broad troughing supports transition to a
less-warm and possibly wetter pattern.

MARINE...
A dew point boundary working southward across southern Lake Huron
and the Thumb may produce an isolated shower or thunderstorm late
this afternoon and evening across southern Lake Huron.  Other then
that, high pressure over the Mid West will provide a west northwest
flow across the lakes through Saturday morning.  As the high passes
through, winds will become light and variable Saturday afternoon.
Winds will become easterly Saturday night then veer to the southwest
while increasing by Sunday afternoon ahead of an advancing cold
front. This front will bring showers and thunderstorms across the
lakes that will linger into Sunday night.  The new week will
start off with dry weather on a northwesterly flow.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...Heat Advisory until 10 PM EDT this evening FOR MIZ047-048-053>055-
     060>063-068>070-075-076-082-083.

Lake Huron...NONE.

Lake St Clair...NONE.

Michigan waters of Lake Erie...NONE.

&&

$$

AVIATION.....BT
DISCUSSION...JVC/DT
MARINE.......DRC


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