Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 221918
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
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.

&&

.PREV DISCUSSION...
Issued at 101 PM EDT Wed Mar 22 2017

AVIATION...

Essentially no weather to speak of for the next 18-24 hours.  Two
short term issues are rapidly resolving themselves this afternoon.
First, lake effect cloudiness off Lake Huron extended down into
northern metro Detroit area briefly resulted in sub 4KFT cigs, but
drier air mixing through the convective boundary layer has eroded all
but shorteline adjacent clouds. Second, mixing over the thumb region
has temporarily resulted in northerly winds gusting to 20 knots. As
high pressure footprint gets more established this afternoon expect
gradient and wind speeds to weaken substantially. Only other issue
will be advance of mid and high cloud in warm advection ahead of next
advancing short wave in the DTW area in the last 6 hours of the TAF
on Thursday.

For DTW...Lake effect cloud and weakening pressure gradient to
result in mostly clear skies and lessening winds this afternoon and
tonight over the DTW airspace. Some mid and high cloud expected
Thursday afternoon but bases likely to be at or above 10KFT.

//DTW THRESHOLD PROBABILITIES...

* None


&&

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

$$

DISCUSSION...SF/JD
MARINE.......SF
AVIATION.....05


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