Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 151548
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1148 AM EDT Tue Aug 15 2017

.UPDATE...
Issued at 1148 AM EDT Tue Aug 15 2017

High pressure north of Superior is nosing into WI. Low- level
northerly flow is providing only very weak cool/dry advection,
even though the primary cold front is exiting lower MI. Earlier
layered has exited ne lower MI, with a cu field in its wake
(especially over nw lower MI). A couple of wanna-be sprinkles seen
within this cu field, mainly in Kalkaska Co. Further nw, marine
stratus deck is making inroads into upper MI, though is mixing out
somewhat along its leading edge. That lead edge has pushed into
the Paradise/Whitefish Pt area.

Will continue to monitor the cu field, but 500mb heights and thus
temps aloft will be rebounding as the upper trof moves further
away, and shortwave ridging advances from the upper MS Valley.
Hard to see more than a sprinkle or two. To the north, anticipate
an increase in cloud cover in western Chip/Mack Cos, but only
places near Lk Superior should have a truly gloomy afternoon.

UPDATE Issued at 747 AM EDT Tue Aug 15 2017

A few showers have popped up in the Ltl Trav Bay area. These
appear to be firing along a secondary surface trof axis,
associated with a very weak vort max aloft that trails the primary
upper trof. There may also be a lake contribution, with upstream
surface temps in the mid/upper 50s and northern Lake MI water
temps in the upper 60s. Supporting the latter are model progs
(like the RAP) that don`t bring precip inland to any great
degree, but do migrate a few showers downlake (in a sense) toward
Gd Trav Bay. Regardless, will cautiously add isolated showers for
a few hours this morning for a small-ish portion of nw lower MI,
otherwise taking a wait-and-see approach.

&&

.NEAR TERM...(Today through Tonight)
Issued at 352 AM EDT Tue Aug 15 2017

High impact weather potential: None.

Pattern synopsis and forecast:

Broad upper troughing continues across the Great Lakes, with main
shortwave and associated low pressure now pushing into Lake
Michigan. There is a nice little pocket of forcing (but weakening),
highlighted by weak low to mid level WAA, upper divergence in
entrance region of 80+kt jet, and of course DPVA. Most of this
forcing was tracking across the GTV Bay region where rainfall was
most concentrated. Intensities have been on the lighter side with
cloud bases somewhat high in most areas (above 7kft). While there
was some rapid clearing seen behind the wave, there were two areas
of stratus and fog. One was behind a cold front in srn Ontario, and
another in Wisconsin on the nrn periphery of the sfc low. Low level
winds were north in Wisconsin, and this area of stratus/fog will not
impact nrn Michigan. However, the Ontario low cloud may be able to
scrape into portions of eastern upper near daybreak or so.

The area of rainfall scooting primarily across the GTV Bay region is
expected to weaken over the next few hours, with the areal extent of
rain diminishing with time. Much drier air fills in behind for the
morning (outside of maybe some of that stratus getting into eastern
upper. Any of this around will quickly erode with daytime cumulus
developing with diurnal heating. Highs will reach the upper 70s to
lower 80s most areas. Skies will turn rather clear into the evening
with only some increase of higher level cloud overnight. Lows are
likely to tank into the low to mid 50s most areas, with the colder
low lying regions sneaking into the upper 40s for what should be a
30+ diurnal swing.

&&

.SHORT TERM...(Wednesday through Thursday)
Issued at 352 AM EDT Tue Aug 15 2017

...Potential for heavy rain Thursday...

High pressure/ridging holds on for one more day yielding pleasant
summer conditions Wednesday with partly sunny skies and warm
temperatures. Meanwhile, a trough currently in the intermountain
west will emerge into the Plains and spin up an area of low pressure
which will track across the northern Great Lakes Thursday into
Friday. This is expected to bring showers and scattered
thunderstorms to the region. Heavy rainfall is also possible with
precipitable water amounts pushing an impressive 2 inches. Chances
for showers and possible thunderstorms arrive late Wednesday night.
Went ahead and went with categorical pops on Thursday and will
continue to mention the heavy rainfall potential in the hazardous
weather outlook. 0-6 km bulk shear is around 40 knots but abundant
cloud cover will likely hinder instability...but there is still the
potential for gusty winds in any thunderstorms.

.LONG TERM...(Thursday night through Monday)
Issued at 352 AM EDT Tue Aug 15 2017

Low pressure tracks by to our northwest Thursday night with residual
troughing extending into Friday. This should lead to cooler
temperatures and possibly lead to lingering showers and drizzle off
of Lake Superior (mainly across eastern upper) with marginal over
lake instability. Another northern stream short wave may bring
another batch of showers Saturday (per the ECMWF). The blend doesn`t
have any pops so went ahead and put in slight chance for now. High
pressure and ridging should lead to precipitation free conditions as
well as warmer temperatures Sunday and Monday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 634 AM EDT Tue Aug 15 2017

Any fog around the airports will burn off quickly this morning
while drier air fills into nrn Michigan resulting in just some
scattered cumulus this afternoon with lake breezes. Mostly clear
skies into this evening with just some higher level clouds later
tonight. Light winds expected through the period.


&&

.MARINE...
Issued at 352 AM EDT Tue Aug 15 2017

High pressure builds into the Great Lakes today, and will stick
around through Wednesday resulting in light winds (afternoon lake
breezes). The approach of low pressure Wednesday night into Friday
morning will bring good chances for rainfall, possible thunderstorms
and gustier conditions under a tighter pressure gradient with near
neutral stability. Advisories are a decent chance.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...JZ
NEAR TERM...SMD
SHORT TERM...AS
LONG TERM...AS
AVIATION...SMD
MARINE...SMD



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