Area Forecast Discussion
Issued by NWS Gaylord, MI

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865
FXUS63 KAPX 271855
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
255 PM EDT Sun May 27 2018

.UPDATE...
Issued at 1052 AM EDT Sun May 27 2018

Tweaked the grids a bit, but overall, didn`t change the forecast
much. Tried to time the wind shift/convergence line with the
latest model data, and then time the pops with that. The dying MCS
to the west will primarily remain to the west with high clouds
just making it into the western part of the forecast area, late in
the afternoon. They may not be much more than scattered
themselves. The sounding this morning, showed a typical summer
type sounding, with some instability, but not enough for things to
get going, unless some sort of trigger moves in. This will
probably be the Lake Huron lake breeze boundary, that will
eventually get run over by the synoptic winds late in the day as a
weak cold front pushes into the region late in the morning/early
afternoon.

&&

.NEAR TERM...(Today through Tonight)
Issued at 325 AM EDT Sun May 27 2018

...Very warm and humid, possible storms northeast lower...

Primary Forecast Concern...Pops and thunderstorm coverage.

Showers and thunderstorms across northwest lower helped along by a
short wave moving across Lake Michigan are expected to track across
the remainder of northern lower early this morning.
Meanwhile...heights slowly build over the region through tonight.
This will lead to hot and humid conditions today and warm and muggy
conditions tonight. Surface dewpoints rise into the oppressive lower
and middle 60s. As far as thunderstorm development goes today, no
additional large scale triggers appear to be in the works. Looking
at model sounding, it appears like a strengthening low and mid level
cap across much of the forecast area. However, this could be wiped
out by an easterly flow lake breeze off of Lake Huron which will
converge with the prevailing westerly flow so we`ll likely to get
scattered coverage of thunderstorms out that way this afternoon. As
far as the potential for severe goes wind fields are rather light
with 0-6 km bulk shear generally under 25 knots. Meanwhile, freezing
levels increase to about 12,500 but wet bulb zero heights drop to
under 8,000 feet so some mainly small hail could be had I suppose.
850 mb temperatures in the plus 18-19 C range should push highs from
the lower 80s across eastern upper to the lower 90s across portions
of northern lower. Lows tonight ranging from the middle 50s north to
the lower 60s south.

&&

.SHORT TERM...(Monday through Tuesday)
Issued at 325 AM EDT Sun May 27 2018

...Still very warm with small rain chances...

High Impact Weather Potential...A thunderstorm or two possible on
Monday.

Pattern Synopsis/Forecast...A closed low will be opening up over the
Rockies on Monday while a downstream ridge over the Plains slowly
drifts towards the Great Lakes. A few lobes of energy breaking off
from the parent low will round the northern periphery of the ridge,
diving into northern Michigan at times through Monday night. By
Tuesday, the ridge axis will sit overhead with high pressure also
building at the surface.

Primary Forecast Concerns...Lingering heat and Monday`s small
chances for showers and thunderstorms.

With the upper ridge axis slowly approaching northern Michigan and
925/850mb temperatures still hovering around 2 to 3 standard
deviations above the mean, the early season heat will linger into
Monday. Latest guidance has come in a tad warmer and would suggest
highs across interior northern Lower in the upper 80s to lower 90s.
Wouldn`t be surprised if a few locations sneak into the mid 90s. Low
level winds will be light and variable, which makes it difficult to
pinpoint any potential warmer downsloping areas. A weak cold front
dropping in late Monday will usher in a slightly cooler and less
humid airmass for Tuesday.

Overall, Monday`s rain chances will be rather slim as high pressure
builds into the region. Models still suggesting a decaying MCS may
impact a portion of eastern Upper Monday morning. Passing weak
disturbances aloft may be enough to trigger a few additional showers
and storms Monday afternoon and evening. However, weaker mid-level
lapse rates will limit instability compared to over the weekend, and
bulk shear looks marginal. Storm development would be more favored
across the southern half of the forecast area, but severe weather is
unlikely. Most guidance showing a dry Tuesday.

.LONG TERM...(Tuesday night through Saturday)
Issued at 325 AM EDT Sun May 27 2018

High Impact Weather Potential...Showers and some thunderstorms may
bring heavy rainfall to a portion of northern Michigan Wednesday
night through Thursday.

Upper level ridge looks to be quickly shunted eastward heading into
midweek by the remnants of Alberto, which are progged to accelerate
northward into Lower Michigan by late Wednesday as they interact
with toughing over the Plains. This would bring a surge of abundant
Gulf moisture into northern Michigan, with PWATs approaching 2
inches by Thursday morning (+3 to 4 sigma for the end of May). As a
result, will be monitoring the potential for some heavy rainfall
Wednesday night into Thursday. Models remain in decent agreement
with bringing the remnants through our neck of the woods, but expect
to see some fluctuations in the system`s eventual track as it hasn`t
even made landfall yet. Given high amount of spread in ensemble
guidance, present confidence remains low in exactly where the
heaviest rain will materialize, but latest model consensus favors
areas west of I-75. Alberto remnants become absorbed by the incoming
trough sweeping through Thursday night into Friday. High pressure
then builds in at the surface and aloft on Saturday with cooler (but
still above normal) temperatures for the weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 243 PM EDT Sun May 27 2018

Main concern is the convective risk today and into Monday. The
main wind shift/convergence line looks to have just cleared APN
and is continuing east, into Lake Huron. This leaves thunderstorms
moving through the rest of NE Lower MI This afternoon/evening
before this threat ends. However for the TAF sites, PLN, TVC, and
MBL, should remain rain free through 12z/Mon as the main trigger
is east, and the next threat isn`t until after 12z/Mon. APN has a
small chance, but considering that the SHRA/TSRA TRigger line is
now past APN, think that the small chance will diminish quickly
into the afternoon.

As mentioned the next threat is after 12z/Mon as a complex of
thunderstorms moves into N WI/W Upper. However, the models that
have this complex, cause the thunderstorms to fall apart over N
Lake Michigan, before affecting TVC/MBL. That will be something to
keep an eye on, but for now think that NW lower will remain rain
free.

&&

.MARINE...
Issued at 325 AM EDT Sun May 27 2018

Winds will remain generally light through Monday. However, a
slight uptick is expected this afternoon with a brief period of
10-15 kt gusts into the early evening before once again returning
to the 5-10 kt range. The potential for scattered thunderstorms will
continue into Sunday evening over Lake Huron. Storms that do
develop could produce some locally stronger winds, lightning, and
small hail.


&&

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

$$

UPDATE...JL
NEAR TERM...AS
SHORT TERM...MK
LONG TERM...MK
AVIATION...JL
MARINE...AS



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