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000 
FXUS63 KDTX 191641
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1141 AM EST Sun Nov 19 2017


.AVIATION...

MVFR/lower VFR stratus will persist into this evening within cold 
WNW flow. Scattered flurries will even bring brief vsby reductions 
this afternoon. However, backing winds to the SW will bring drier 
(and milder) air into area and shut down this lake response. So, VFR 
conditions will develop overnight and hold into Monday with sct 
conditions much of the time.

For DTW...Ceilings aob 5kft expected into the evening with hit/miss 
light snow showers bringing spotty vsby reductions. SW flow 
overnight into Monday will lead to solid VFR and skies clear out.

//DTW THRESHOLD PROBABILITIES...  

* High for cigs aob 5kft into this evening.

* High for snow ptype

&&

.PREV DISCUSSION...
Issued at 257 AM EST Sun Nov 19 2017 

DISCUSSION...

Sprinkles and flurries were moving across the forecast area early 
this morning in the wake of the strong storm over the St. Lawrence 
Valley. As the colder air continues filter into the area, expect all 
of these to change to flurries/scattered snow showers.  Today will 
feature cyclonic flow in the wake of the storm with some help from 
the lakes, diurnal response giving some boundary layer instability 
with convective depths up to around 8000 feet and a shortwave moving 
over the region. Therefore will keep the 30 to 40 POPs in the 
forecast for those snow showers today. Will also keep the high 
temperatures closer to the mid 30s with plenty of clouds, raw model 
output colder than guidance and the cooler trend in that guidance.

High pressure ridge folds over Lower Michigan this evening which 
will not only end the cyclonic flow but also introduce some drier air 
in the boundary layer. Expect some partial clearing tonight, but 
there is a jet streak diving down into the lakes late tonight with 
some modest jet support and 500 mb Fgen and deformation. This will 
support some mid and high clouds from about 09z to 15z.

After that skies will be mostly sunny for the bulk of the day on 
Monday. Southwest gradient strengthens as the high moves east and 
the next potent system heads toward the northern Great Lakes. 
Subsidence inversion is very low which will keep us from mixing too 
much wind, but will also keep the temperatures in check in the mid 
to upper 40s.  

The cold front moves through Lower Michigan on Tuesday. There is 
decent dynamic support through a very good depth on Tuesday, but it 
takes time for the response since the moisture is marginal. Will 
have just chance POPs for the eastern portions of the forecast area 
Tuesday afternoon.

Seasonably cool high pressure builds into the region on Wednesday 
and for Thanksgiving. This high will keep it dry enough for a fair 
amount of sun on Wednesday and Thursday to offset the cooler regime. 
Friday will be a transition day before the next system on Friday 
night and Saturday which will bring our next chance of rain and/or 
snow.

MARINE...

Northwest gusts to gales over the open waters of Lake Huron will 
diminish through the morning as high pressure works into the area.
A period of moderate to fresh westerlies will then take hold through 
Monday followed by the the development of strong southwest flow 
Monday night into Tuesday as low pressure tracks across northern 
Ontario. Gusts to low-end gales will be possible during this time 
and a fresh gale watch is now in effect.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Gale Watch from Monday evening through Tuesday afternoon for LHZ362-
     363-421-462>464.

     Small Craft Advisory until 10 PM EST this evening for LHZ421-441.

     Small Craft Advisory until 4 PM EST this afternoon for LHZ442-443.

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

$$

AVIATION.....DG
DISCUSSION...RBP

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