Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 191750

Area Forecast Discussion
National Weather Service Gaylord MI
150 PM EDT Wed Apr 19 2017

Issued at 1055 AM EDT Wed Apr 19 2017

Overview: Short wave trough continues to move through the northern
lakes region this morning. Associated elongated surface low is
centered over SE Ontario with a trailing shallow cold front
slicing down through far NE lower Michigan (just east of West
Branch as of 14Z). Wavy front continues down through the midwest
to another short wave impulse and area of low pressure in the
central plains just lee of the Rockies (system for tonight-
tomorrow). Already a fairly expansive area of rainfall with this
system stretching from Iowa into the Dakotas. But in the wake of
the shallow front...low stratus has overspread eastern upper and a
chunk of northern lower Michigan this morning and knocked temps
down a good 5 to 10 degrees.

Rest of today...shallow cooler airmass/low cloud cover continues
to overspread the region over the next few hours...although
progression of stratus into the eastern/southeastern parts of the
CWA has seemingly slowed/stalled with advent of daytime heating.
Will just have see just how far south/east the low clouds get...but
either way daytime heating/mixing will begin to erode/thin out
the low clouds as we go through the afternoon.

Otherwise...relatively quiet today through this evening. Upstream
system still expected to ramp up rather quickly later today and
move into the region tonight...spreading rainfall into the region
overnight. Heavy rainfall potential/minor flooding is the biggest
forecast concern for us. Current QPF forecasts are largely below
flood guidance although recent saturated soils may play a role.


.NEAR TERM...(Today through Tonight)
Issued at 357 AM EDT Wed Apr 19 2017

...Widespread rain showers and possibly some thunder developing late

High Impact Weather Potential...Slight chance of thunder late

Pattern Synopsis/Forecast...Low pressure continues to make its way
thru Lake Superior toward the Ontario/Quebec border early this
morning. Associated cold front extends from the low thru Eastern
Wisconsin and Iowa to another developing area of low pressure
currently centered over Eastern Colorado. Closer to home...a few
areas of light rain continue to track thru Eastern Upper Michigan
just ahead of the initial low center...with a narrow band of
diminishing showers along the associated cold front along the
Wisconsin/Illinois border. Temps are still relatively mild across
our area...ranging from the mid 40s in Eastern Upper Michigan to the
mid 60s in our far SW CWA.

Initial low will reach the Ontario/Quebec border this morning as the
cold front slides thru our CWA resulting in only some cloud cover
and maybe a sprinkle or two. Front will stall over far Southern
Lower Michigan this afternoon as the secondary low deepens and lifts
NE into Iowa by this evening. As the low center continues NE into
Southern area of deep moisture ahead of the low will
surge into Michigan...producing widespread showers from SW to NE
across our entire CWA very late tonight. Latest short term models
have pushed area of max precip slightly further has been
the trend over the past few runs. Models are also still suggesting a
slight chance of thunder across the southern half of our CWA late
tonight where MUCAPES of around 500 J/kg develop within the 850 mb
theta E ridge axis.

High temps this afternoon will range from the upper 40s in Eastern
Upper Michigan to the lower 60s near Saginaw Bay. Low temps tonight
will range from the upper 30s in Eastern Upper Michigan to the mid
40s in our SW CWA.


.SHORT TERM...(Thursday through Friday)
Issued at 357 AM EDT Wed Apr 19 2017

...Heavy rains possible early Thursday...

High Impact Weather Potential: Will definitely need to monitor river
levels Thursday and Friday if anticipated heavy rain Wednesday night
and early Thursday is realized.

Pattern Synopsis/Forecast: Progressive pattern set to continue for
the foreseeable future with very strong flow emanating from the
Pacific. Dual shortwaves rotating within this flow regime look to
merge just to our west early Thursday, eventually rotating across
our area as a closed mid level low later Thursday and Thursday
night. Attendant core of strong dynamics collocated with northward
surging moisture plume looks to drum up a rather decent rain event
for northern Michigan later Wednesday night and into Thursday

Primary forecast concerns: Rain amounts Thursday. Lingering showers
into Friday. Cloud and temperature trends through the period.

Details: Latest trends continue to suggest widespread showers across
much of the area first thing Thursday morning. Forcing will be
rather impressive on leading edge of dry slot and along nose of
stout (near 50 knots) low level jet. While not tremendous, more than
enough moisture will be available for this forcing to act upon, with
precipitable water values pushing to near one inch values. Still
some uncertainty with exactly where heaviest rains will reside,
although dprog/dt of nearly all guidance has shown a slow northward
adjustment with the heaviest precipitation axis. Could even hear a
few rumbles of thunder, with any storms only enhancing precipitation
rates. Forcing and dry slot will remain fairly transient, with most
widespread and heaviest showers likely exiting east of our area by
afternoon. Lingering light showers expected during the afternoon,
with the greatest focus across eastern Upper with less dry slot
intrusion and closer to stronger mid level dynamics. All told, could
see another quarter to half inch of rain Thursday, and when combined
with Wednesday nights anticipated rains, will push some areas to
near, or even over, one inch totals. This may be enough to result in
some minor river flooding in our typical more flashy basins.

Light showers linger Thursday night into at least the start of
Friday. Cold air advection will also be increasing during this time,
and might be enough to force a rain/snow mixture at times,
especially across eastern upper Michigan. Will continue to advertise
a dry Friday afternoon and night for now. Not entirely sold on this
idea however, as mid level troughing still lingers over the northern

.LONG TERM...(Friday night through Tuesday)
Issued at 357 AM EDT Wed Apr 19 2017

Trends continue to support a dry weekend as surface high pressure
builds overhead. There are some hints of a wave dropping out of
Canada on Sunday. Looks moisture starved for now, but something to
watch. Plenty of uncertainty about early next week. Guidance
consensus blend supports at least some shower threat by Tuesday.
Sure cannot disagree with this idea. Temperatures will average near
to slightly below long term normals for this time of year.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 150 PM EDT Wed Apr 19 2017

MVFR stratus remains shrouded over parts of northern lower
Michigan...primarily the tip of the mitt and Grand Traverse Bay.
Stratus has been lifting/eroding steadily over the last few hours
and should continue to do so...returning terminal sites to VFR
conditions heading into the evening hours.

Upstream...low pressure in the plains will deepen and push into
the region later tonight into Thursday. This system will bring a
round of widespread rainfall to all of northern Michigan overnight
through thursday and solid MVFR conditions.


Issued at 357 AM EDT Wed Apr 19 2017

Winds and waves will likely ramp back up to SCA criteria late
tonight...and may even reach gale warning criteria on Thursday for
some locations as deep low pressure tracks thru the Western Great
Lakes region. Widespread rain showers will also develop as this
system slides thru Michigan...with a few thunderstorms also




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