National Weather Service - Area Forecast Discussion

000
FXUS63 KAPX 161748
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
148 PM EDT Thu Aug 16 2018

.UPDATE...
Issued at 1137 AM EDT Thu Aug 16 2018

Water vapor imagery reveals broad mid level troughing across the
upper Midwest and Great Lakes this morning. Closed mid level low
is over the Nebraska/South Dakota border while a more subtle
short-wave appears to be running northward up through far eastern
Wisconsin/Lake Michigan. Attending surface low is over the
Midwest. Some showers ongoing in the Detroit area into the Ohio
Valley and back over Iowa near the mid level low. No precip across
northern Michigan for the moment, although there were a few radar
returns across Luce/Alger/Schoolcraft counties earlier.

Owing to some mid level warming over the last 24 hours, morning
APX sounding and SPC mesoanalysis reveals much less MUCAPE across
northern Michigan this morning as compared to yesterday, maybe
pushing 1000 J/KG in the far southern counties as of 14Z. So, a
little more "stable" to start the day.

Rest of today into tonight: Eastward progression of mid level low
certainly is a bit slower than advertised this time yesterday, now
not slated to slide through lower Michigan until later tonight
into Friday. There is that weaker piece of short-wave energy that
will be sliding up through the region and provide some modest
synoptic scale forcing. But the overall driver of shower/thunderstorm
development will once again be regulated in the mesoscale.

Per SPC mesoanalysis forecast, daytime heating should push MLCAPE
values up over 500 J/KG across northern lower Michigan this
afternoon, with minimal CINH. Again, a bit less than Wednesday,
but enough. With light east to northeasterly low level flow, low
level convergence is typically maximized down through NW lower
Michigan (essentially along the US-131 corridor), with N/NW flow
coming off Lake Michigan. That is where I`ve focused the highest
chances for showers/storms this afternoon into the evening. Low
severe storm threat owing to weak winds through the column and
higher freezing levels (14.3K feet). Stronger updraft might be
able to produce some hail although with less instability today,
I`m skeptical. But, we will have to watch for training/back-
building updrafts that could lead to localized heavy rain.

&&

.NEAR TERM...(Today through Tonight)
Issued at 222 AM EDT Thu Aug 16 2018

...Another round of afternoon/evening showers and storms...

High Impact Weather Potential...Thunderstorms possible across much
of Northern Lower Michigan this afternoon and evening with the
potential for heavy rain and some gusty winds.

Pattern Synopsis/Forecast...A stationary front remains draped across
Lower Michigan early this morning attached to low pressure centered
over the Mid Mississippi Valley. 500 mb low is centered over the
Northern Plains just west of the surface low center. Closer to
home...all is quiet across Northern Michigan with no precip
occurring across our CWA attm.

As we head into today and tonight...surface low will slide eastward
along the stationary front into the Southern Great Lakes as the
upper low moves thru Iowa into Southern Wisconsin and Northern
Illinois. Northern edge of the moisture shield associated with this
system will lift northward into Northern Lower Michigan today.
Increasing lift and moisture combined with strengthening diurnal
instability will kick off scattered to numerous showers and
thunderstorms across much of Northern Lower Michigan by this
afternoon and continuing into this evening. Wind fields will remain
too weak for the development of severe storms...but certainly cannot
rule out the possibility of some gusty winds with some storms. Heavy
rainfall is also possible. Showers and storms will diminish in areal
coverage and intensity later this evening and overnight with loss of
daytime instability.

Expect another warm mid August day across the Northwoods this
afternoon...with high temps warming to a few degrees either side of
80. Low temps tonight will cool back into the 60s.

&&

.SHORT TERM...(Friday through Saturday)
Issued at 222 AM EDT Thu Aug 16 2018

High Impact Weather Potential: Possible thunderstorms
over far southeastern CWA Friday

High pressure will build in quickly behind departing low pressure
system mentioned in the previous forecast period above. This will
diminish precipitation chances by Friday afternoon for most parts of
the forecast area and providing a partly cloudy and warm day with
light winds. The exception will be over the far southeastern part of
the forecast area where lingering showers and possibly even
afternoon thunderstorms could develop where lingering moisture and
instability will be the greatest. These showers and storms that may
linger will move off to the east as high pressure continues building
over northern Michigan and she end by sunset. Skies will continue
clearing producing another sunny and warm day Saturday with light
winds once again and high temperatures into the upper 70s to low 80s
during the afternoon hours, while low temperatures Saturday morning
will be in the upper 50s to low 60s. Some models are beginning to
hint at some late afternoon/early evening showers popping up over
inland portions of northern lower on Saturday...possibly lake breeze
convergence.

.LONG TERM...(Saturday night through Wednesday)
Issued at 222 AM EDT Thu Aug 16 2018

High Impact Weather Potential...Minimal

High pressure continues to build into the forecast area providing
sunny skies and precipitation free weather through the remainder of
the weekend. The beginning of the work week looks like a return of a
more active weather pattern with chances of precipitation returning.
Temperatures will be reaching into the low to mid 80s during the
afternoon hours Sunday and Monday, but only reaching into the 70s
Tuesday and Wednesday behind a cold front that is progged by models
to to pass through northern Michigan late Monday/early Tuesday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 147 PM EDT Thu Aug 16 2018

An area of low pressure over the Midwest will slowly work through
the lower lakes region through Friday. Combined with daytime
heating, showers and some thunderstorms remain possible across
northern lower Michigan this afternoon/evening, primarily across
interior areas. TVC and MBL probably have the best shot at seeing
some of this activity today.

Overall quiet weather again tonight. Some fog again overnight
through early Friday morning.


&&

.MARINE...
Issued at 222 AM EDT Thu Aug 16 2018

Winds and waves are expected to remain below small craft advisory
criteria through the forecast period, with winds trending northwest
as a weakly organized system passes through the northern Great
Lakes. Some thunderstorms are possible over Lake Michigan and Lake
Huron today and again Friday over Lake Huron. Locally heavy rains
and some wind gusts are possible with these storms. Looking
ahead...the next chance for headlines may be during the beginning of
the next work week with a cold frontal passage.


&&

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

$$

UPDATE...BA
NEAR TERM...MR
SHORT TERM...TL
LONG TERM...TL
AVIATION...BA
MARINE...TL

NWS APX Office Area Forecast Discussion