Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 181025
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
625 AM EDT Thu May 18 2017

.NEAR TERM...(Today through Tonight)
Issued at 331 AM EDT Thu May 18 2017

...Showers and storms today then a return to more seasonable
temperatures...

High Impact Weather Potential...Thunderstorms...marginal risk for
severe. Gusty winds this afternoon.

Pattern Synopsis/Forecast...Potent short wave impulse and attending
surface low is now pushing through Wisconsin toward the upper
peninsula this morning...leading surface trough/front stretches
through the eastern U.P. and trailing cold front is back through
the plains. Several lines/clusters of showers/storms precedes the
wave and have been advancing through the western Great Lakes over
the last several hours. Strongest convection has been across the
southern half of the state and lower Great Lakes where there is at
least some surface based component to the instability. We
continue to track the outflow remnants of a bow echo across
central and southern lower Michigan that continues to produce new
convection some beefier wind gusts getting close to severe levels.

Another cluster of convection is pushing out of eastern upper
Michigan ahead of the advancing short wave...and is more elevated
in nature...as decent elevated instability plume has been steadily
advecting into our area through the night driven by a strong low
level jet ahead of the wave.

Short wave impulse and attending surface low will advance into
the central/eastern U.P. this morning...then eastward out of the
state during the course of the afternoon. This will drag attending
cold front through the CWA and usher in cooler temperatures
heading into tonight.

Primary Forecast Concerns...Marginal severe storm threat until
FROPA. Possible wind advisory gusts for some areas.

Today: Ongoing convection is expected to largely diminish or be
out of the CWA area within the next few hours. But...we still
have to push the cold front through the region later this morning
into the afternoon as well as the "wrap around" deformation
component to this system this afternoon/early evening. Ahead of
the front...we will have the opportunity to warm temperatures back
through the 70s for parts of northern lower Michigan and forecast
soundings suggest MLCAPE values up over 1000 J/KG across the E/SE
part of the CWA prior to fropa. So...will have to keep
thunderstorm chances going into the afternoon hours ahead of the
front. And...with 50 to 60 knots of mid level flow remaining in
place...I still think we have at least a low end risk for strong...
possibly severe storms particularly over the E/SE counties.

Finally...with those stronger winds along...warm temperatures and
deeper mixing...we should get some rather strong wind gusts later
this morning and afternoon particularly through central and
southern lower Michigan. A bit marginal...but some gusts pushing
45 mph (wind advisory) are possible down toward Saginaw Bay and
will thus hoist a wind advisory for Gladwin/Arenac
counties...lining up with GRR and DTX advisories.

Tonight: Strong push of dry air and high pressure building down
out of south-central Canada will clear things out as we go through
the night. Fairly cool temperatures anticipated with lows dipping
into the lower to middle 30s for much of the area. Frost potential
is still a big question mark as we will hang on to a bit of wind
for much of the night. Have patchy to areas of frost in the
forecast for now...and day shift will need to further evaluate the
need for a frost advisory.

&&

.SHORT TERM...(Friday through Saturday)
Issued at 331 AM EDT Thu May 18 2017

...Dry Friday, Rain Saturday night?...

High Impact Weather Potential...Wind and low humidity Friday
afternoon.

Pattern Synopsis/Forecast...Extremely dry air arrives early friday
morning as the tail of the moisture with the sfc low/cold front gets
chased out. 850 mb RH is < 10% and with the mixing there will be
fair amount of dry air at the sfc. Models are showing that the winds
could be around 10 knots with gusts to 15 knots. This gives us a 2
out of 3 scenario for elevated fire danger. As we get into Friday
night, was concerned about frost potential, but with the winds
expected overnight, not sure about it now as the models show a
constant wind overnight that the temperatures are likely to get hung
up in the mid to upper 30s, so that frost is unlikely.

Saturday, the moisture, warm front and sfc low are all moving into
the region. Models suggest that the rain is just in the vicinity of
MBL by 15z and near TVC by 18Z so will have the chance of showers
and thunderstorms, mainly south of M-32 as the showalter index drops
below 0c and continues that way through 12z.

Primary Forecast Concerns...The low RH idea from yesterday is
looking better at the SREF Plumes for 2m dewpoint and RH have
lowered over the past 24 hours and are now beginning to settle "in
the ball park." So it is looking like yesterday`s call of lowering
dewpoints was a good one. There is still some uncertainty as the
winds look to be NE through the day.

.LONG TERM...(Saturday night through Wednesday)
Issued at 331 AM EDT Thu May 18 2017

High Impact Weather Potential...None.

Extended (Sunday through Wednesday)...Sunday, continue with the
chance of showers and thunderstorms as the cold front moves through,
although a decent 500-700 mb layer dry slot moves in over the front,
so there light scattered rain showers are expected. Monday, mainly
dry as the 500 mb low moves east of the region, but far enough north
to possibly get something into E Upper. Cold front moves into the
region Monday night and continues into Tuesday with a 500 mb low.
The low hangs out over the state through the day and moves east
Wednesday night. So more rain showers expected.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 625 AM EDT Thu May 18 2017

VFR conditions remain across northern lower Michigan for the time
being. Cold front will swing through the region later this morning
and the afternoon. This will produce additional showers and
possibly some thunderstorms...particularly down near Saginaw Bay.
Behind the front...a period of MVFR conditions may develop as
cooler air slides into the region. But drier air builds in
overnight into Friday and bring a return to VFR weather heading
into Friday.

Gusty SW winds anticipated ahead of the front today...veer north
and diminish tonight.

&&

.MARINE...
Issued at 331 AM EDT Thu May 18 2017

Gusty winds today into tonight will lead to small craft advisories
on the lakes. Will evaluate the need for gale warnings for a few
locations. Winds diminish later tonight into Friday.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WIND ADVISORY from 11 AM this morning to 8 PM EDT this evening
     for MIZ041-042.
LH...SMALL CRAFT ADVISORY from 1 PM this afternoon to noon EDT Friday
     for LHZ346>349.
LM...SMALL CRAFT ADVISORY from 2 PM this afternoon to 2 AM EDT Friday
     for LMZ323-341-342.
     SMALL CRAFT ADVISORY until noon EDT Friday for LMZ344>346.
LS...SMALL CRAFT ADVISORY from 2 PM this afternoon to midnight EDT
     tonight for LSZ321-322.
&&

$$

NEAR TERM...TBA
SHORT TERM...JSL
LONG TERM...JSL
AVIATION...TBA
MARINE...TBA



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