Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 230355
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1155 PM EDT Wed Mar 22 2017

.AVIATION...

Slow eastward exit of expansive arctic high pressure will sustain a
stretch of favorable aviation conditions tonight and Thursday.  The
accompanying high degree of stability ensures a clear sky through
the overnight period. Advancement of warmer mid level air into the
region will bring a thickening/lowering high based cloud throughout
Thursday.  Warm air advection will eventually support a several hour
window for light rain development Thursday night.  Uncertainty yet
in the degree of low level moistening during this time, simply
supporting an introductory lower VFR mention at this stage.  A more
significant reduction in conditions will be plausible by Friday
morning /particularly PTK northward/.  Light winds under weak
gradient flow to become southeasterly Thursday.  Strengthening
southwest flow just off the surface will introduce a low level wind
shear component Thursday night.

For DTW...Thickening cloud Thursday to carry CIGS above 5000 ft
through early Thursday evening.  Lowering ceiling thereafter will
bring an increasing probability for sub-5000 ft cigs Thursday night
/after 04z/.

//DTW THRESHOLD PROBABILITIES...

* Medium in cigs falling below 5000 ft after 04z Thursday night.

&&

.PREV DISCUSSION...
Issued at 318 PM EDT Wed Mar 22 2017

DISCUSSION...

Sprawling high pressure in place over the Central Great Lakes, with
the center (1036-1038 MB) slow to exit southeast Michigan Tonight,
providing favorable radiating conditions under clear skies and dry
airmass in place, as surface dew pts reside in the single numbers
across most areas this afternoon. Still, with the shorter nights and
lack of snow cover, expecting mins to only bottom out in the lower
teens across most locations as dew pts come up, otherwise Flint`s
daily record low of 7 degrees would be in jeopardy.

Good warm advection pattern then setting up Tomorrow into Friday,
with a surge of Gulf Moisture lifting into the State Thursday night,
as 850 mb dew pts rise in the high single numbers. Warm front and
strengthening low level jet (50+ knots) over the Western Ohio Valley
moving into southeast Michigan overnight expected to produce
showers, with an isolated thunderstorm not out of the question as
showalter index falls toward zero with decent mid level lapse rates.
The moisture/instability axis looks to be lifting north of the CWA
on Friday, and thus just a low chance of rain on Friday, mainly
north, and  likely more from low clouds/drizzle as large upper level
ridge sits on top of the area with the cutoff/closed low over the
Central Plains. This is assuming the 12z NAM/GFS moisture/saturation
indicated at 925 MB level is correct, otherwise could be looking at
temperatures pushing well into the 60s, potentially 70+ degrees at
Detroit as 850 mb temps push toward 10 C.

Kicker system moving onshore of the West Coast Saturday morning,
allowing for Central Plains system to head off to the northeast
toward the area over the weekend.

A frontal boundary draped west to east across Southeast Michigan on
Saturday will act as a focal point for showers throughout the day. A
sharp temperature gradient will exist along the boundary with
temperatures near 40 in the Thumb region north of the boundary and
closer to 60 near the Ohio border south of the boundary. While
uncertainty remains about the exact position of the boundary and
temperatures across Southeast Michigan on Saturday, enough warm air
will likely be in place for rain to be the predominant precip type.
Rain chances then increase on Sunday as the weakening low pressure
approaches Southeast Michigan bringing a better influx of moisture.
Drier conditions arrive briefly Sunday night into Monday as the low
pressure moves east of the region. Rain chances then return late
Monday into Tuesday as a shortwave crosses through Lower Michigan.
Temperatures look to remain mild early next week with highs in the
50s and lows in the 40s Sunday through Tuesday.

MARINE...

Large area of high pressure over the Central Great Lakes region
Tonight, leading to light and variable winds. This high will slide
to the east Tomorrow, allowing for strengthening southerly winds, as
a warm front lifts into the area Thursday night. The warm air
streaming over the cold Lakes is expected to promote stable low
level profiles, limiting wind speeds over Lake Huron to 25 to 30
knots. Winds will diminish on Friday as warm front stalls over Lake
Huron, and then sinks south as a cold front Friday night into
Saturday, resulting in increasing easterly flow as high pressure
builds over Ontario, leading to long duration easterly flow over the
weekend.

&&

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

$$

AVIATION.....MR
DISCUSSION...SF/JD
MARINE.......SF


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