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000 
FXUS63 KDTX 181129
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
729 AM EDT Wed Oct 18 2017


.AVIATION...

High midlevel stability with very low near surface moisture will 
maintaint persistence over southeastern Michigan. Sky will be be 
mainly skc with transparent cirrus possible especially for areas to 
the north. Stout southwest gradient will be in place locally in 
response to very deep low pressure system passing through northern 
Canadian provinces. Gusts near 25 knots will then once again be 
likely through afternoon.  

//DTW THRESHOLD PROBABILITIES...  

* None.

&&

.PREV DISCUSSION...
Issued at 345 AM EDT Wed Oct 18 2017 

DISCUSSION...

Quiet weather pattern through the upcoming weekend as ridging aloft 
and at the surface reside over the region for the most part. Some 
slight eastward drift with the surface ridge centered to our SE will 
occur as a mid level shortwave passes over Wednesday night into 
Thursday, but it looks to build back west for the weekend. Next 
notable system doesn't look to arrive til Sunday into Monday. 

Today will largely be dry and sunny as shortwave ridging split flow 
region slides over the state immediately in advance of a weak 
trough. Very dry airmass and subsidence region will keep the skies 
clear. Will get some gusty winds as the gradient between the 
approaching trough and surface ridge tightens/compresses overhead. 
One limiting factor to winds will be the low mixing heights which 
are forecast to rise to around 3kft. Most model soundings show this 
cap gusts off around 25-30 mph but a couple higher gusts can't be 
rules out. Temperatures today will again rise to around 10F above 
normal which is around 70F. As mentioned in the previous discussion, 
temperatures slightly over achieved and the thermal profile looks to 
warm slightly over yesterday so should only add to the confidence of 
achieving these temperatures with the warm SW flow. 

The strength of the ridge will steer the next upper level wave well 
north of the Great Lakes through northern Ontario and James Bay. The 
weakening cold frontal trough extending southward from this system 
will sweep across Lower MI Wednesday night into Thursday. Little 
fanfare with the trough as the airmass is so dry and surface ridge 
still remains in place. Looks like at best we'll see a period of 
enhanced cloud cover with the trough but that should be about it. 
Highs will fall back into the mid/upper 60s in responds to the weak 
thermal trough as well. 

Surface high builds back over the area Friday into the weekend, 
still positioned for us to receive a favorable SW flow. Upper level 
ridge amplifies over the eastern conus in response to the strong 
trough coming ashore the west coast. Though the trough looks to 
fracture as a potential 140+ kt jet surges east through southern 
Canada, a cold front should track across lower MI sometime Sunday 
into Monday bringing the next chance of showers. With the jet 
quickly refocusing back to our north, warm westerly flow will 
continue behind the front keeping near normal temps across southern 
MI.

MARINE...

A pressure gradient between surface high pressure slowly moving east 
through the Ohio Valley and low pressure in central Canada will 
maintain gusty southwest winds through the midweek period. Small 
craft advisories are again in effect today and tonight for Saginaw 
Bay and the nearshore waters of Lake Huron from Port Austin to 
Harbor Beach. Southwest winds will then diminish slightly this 
evening below 20 knots before maintaining around 20 knots over Lake 
Huron on Thursday.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory until 10 AM EDT Thursday for LHZ421-422-441.

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

$$

AVIATION.....CB
DISCUSSION...DRK
MARINE.......CB

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