Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 301028
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
628 AM EDT Tue May 30 2017


.AVIATION...

The very broad upper level trough will continue to impact
southeastern Michigan throughout the taf period as it is stalled over
Ontario. Most impactful weather will be redeveloping gusty southwest
winds today. High confidence in gusts ranging between 20-30 knots.
Barotropic low will bring little differential advection which
supports a persistence forecast. Diurnal cumulus development is
expected between 5.0 and 6.0 kft agl. Isolated showers will develop
once again this afternoon. Clouds and showers to dissipate this
evening.

//DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 259 AM EDT Tue May 30 2017

DISCUSSION...

Very complex looking water vapor imagery this morning with large
upper low positioned just north of Lake Superior and several notable
shortwaves rotating around it. Next of the larger shortwaves in line
to push through Michigan is currently over Iowa. This feature should
track across the region late this morning and this afternoon,
helping to trigger a few showers or thunderstorms. Coverage is
expected to be less than yesterday, more isolated. Despite still
residing under the H500 cold pool associated with the upper low,
H925/H850 temps will be running about 5 degrees C cooler. This
should provide less instability, plus moisture is looking more
shallow in forecast soundings. CAPE profiles are pretty skinny, but
up to 800 J/kg of SB CAPE by afternoon will provide a chance for
thunder with any cell that develops. Breezy conditions will
redevelop this afternoon with surface tight pressure gradient
maintained by low pressure over Northern Ontario and high pressure
over the southeast states supporting gusts 25 to 30 mph.
Temperatures will run a little cooler today given the cooler thermal
profiles, with highs in the low to mid 70s.

Next pair of shortwaves stretching from Minnesota back through
southern Manitoba should cross Lower Michigan tonight, and will
maintain a slight chance for showers through late tonight until
subsidence behind the wave settles in. The last shortwave trough
axis associated with this low is forecast to pivot through the
Central Great Lakes on Wednesday. This will again provide only a low
chance for showers as the upper low and cold pool begin to lift
east, and temperatures warm aloft. Low-level thermal trough should
move across, holding max temperatures into the mid/upper 60s, while
breezy conditions persist.

High pressure building over the Ohio and Tennessee Valleys will
extend into Michigan Wednesday night and Thursday, bringing a small
stretch of dry and quiet weather before a potentially active pattern
sets up for the end of the week. Models are still not in great
consensus with the larger features over North America, making it
hard to pinpoint where exactly a frontal boundary that will set up
over the Great Lakes and Ohio Valley will be located Friday through
Sunday. Euro and CMC offer the most active scenario, as they are
more aggressive with phasing upper energy over the Great Lakes over
the weekend, keeping the front over Southern Michigan. GFS continues
to build high pressure into the area, drying us out for the weekend.

MARINE...

Persistent gradient within upper level trough will keep gusty
southwest winds in place today over the Central Great Lakes. Gusts
in excess of 25 knots most likely over Saginaw Bay, where a small
craft advisory remains in effect through this evening. Surface winds
will remain out of the west until the end of the week with modest
increases in windspeeds during the daytime.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422.

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

$$

AVIATION.....CB
DISCUSSION...HLO
MARINE.......CB


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