Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 190144
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
944 PM EDT Sun Aug 18 2019

.UPDATE...
Issued at 944 PM EDT Sun Aug 18 2019

Cold advection underway across northern MI, behind a well-defined
cold front crossing se lower MI. Wrap-around moisture and a
secondary surface boundary area contributing to sct showers north
of M-68. This activity will make some se-ward progress over the
next few hours, perhaps making Grayling/APN before fizzling out
toward 1 am. Deeper moisture will be departing, with clearing
already seen in western sections. Cloud cover will linger longest
in the se third of the forecast area, lasting into the late
overnight hours.

Winds have diminished, but remain rather breezy in eastern upper
MI and some coastal locales.

UPDATE Issued at 723 PM EDT Sun Aug 18 2019

Post-frontal winds have been gustier than advertised, including a
very surprising 48 mph gust from PLN. Nothing else has even been
in that ballpark, but 30-40mph has been commonplace. Have boosted
winds this evening.

&&

.NEAR TERM...(Through Tonight)
Issued at 312 PM EDT Sun Aug 18 2019

High Impact Weather Potential: Isolated severe storm potential
southeast

Pattern synopsis/forecast: Challenging forecast with a multitude
of mesoscale features creating havoc with the short range
guidance. Warm front over southern Michigan, with MCV over
western upper and a cold front over northern Wisconsin.

Primary forecast concerns/challenges: Convective evolution through
early evening.

Will there be enough destabilization with diurnal heating behind
the initial batch of convection to result in some additional
shower/tstm activity through the remainder of the afternoon and
early evening? There is not much of anything upstream but the
airmass is still supportive of producing an additional
shower/storm until we get the front through the area later this
evening. So will reluctantly carry some lower POPs into the
evening hours, although wouldn`t be surprised if we don`t see much
re-develop. Instability parameters not that impressive (750-1000
j/kg) and they really begin to diminish after 5 pm. Front slides
through this evening and we may see a few additional
showers develop with a slight uptick in forcing/moisture with
fropa. Drier air begins to overspread the region later tonight
from northwest to southwest, helping to bring surface dewpoints
down. Prior to this, areas of fog may develop over interior areas.
Comfortable temperatures overnight, with lows in the middle 50s
to lower 60s.

&&

.SHORT TERM...(Monday through Wednesday)
Issued at 312 PM EDT Sun Aug 18 2019

...Rain? Not Likely...

High Impact Weather Potential...Minimal.

Pattern Synopsis/Forecast...High pressure builds into the forecast
area for Monday and the day on Tuesday. However, a cold front will
move through the Upper Great Lakes Tuesday night into Wednesday
morning. Models have trended dry as the front moves through during
the night. Will leave the blend, and talk about various outcomes in
the next section.  However, the temperature change will be strong as
we go from 80 on Tuesday to 73 on Wednesday.  High pressure then
builds back into the region on Wednesday afternoon, and allows for
drying.

Primary Forecast Concerns...Main concerns is the varied trend
between the models. The GFS tries to bring something through E Upper
while the latest ECMWF dry across the whole region, save for a few
odd points north of ANJ. The SREF has kept a line through the region
until Wednesday morning before forming something along the Lake
Huron lake breeze. Have opted for the NBM idea, during the dry
period so far.

.LONG TERM...(Wednesday night through Sunday)
Issued at 312 PM EDT Sun Aug 18 2019

High Impact Weather Potential...Minimal

Extended (Wednesday evening through Sunday)...High pressure
remains over the region, and produces dry weather. Saturday and
Sunday, it looks like some sort of boundary is around the region,
and could be an issue, but the trend so far, from run to run, has
been for the chances to diminish. Sunday night on the ECMWF, there
cold be another MCS like was supposed to happen today. We`ll see.
This has not been a good convective season for the models, so no
guarantees for breaking our dryness.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 723 PM EDT Sun Aug 18 2019

VFR. Gusty winds this evening.

Cold front working thru the region, and post-frontal showers will
stay in the Straits region and points north. Low-end VFR cigs will
improve tonight as drier air pushes into the region. Solid VFR on
Monday.

Sw winds will be be gusty this evening. Lighter w to nw winds
Monday.


&&

.MARINE...
Issued at 723 PM EDT Sun Aug 18 2019

SCAs expanded to all marine zones, with a brief period of gusty
post-frontal winds.

Gusty south/southwest winds through early evening with
small craft gusts on Lake Michigan nearshore waters.  Cold front
passage tonight and a period of cold advection/mixing will bring
small craft conditions to Whitefish Bay/St. Mary`s River. Will have
to watch if additional parts of northern Lake Michigan and northern
Lake Huron also require small craft headlines for northwest flow
later tonight.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until midnight EDT tonight for LHZ345>349.
LM...SMALL CRAFT ADVISORY until midnight EDT tonight for LMZ323-341-
     342-344>346.
LS...SMALL CRAFT ADVISORY until 6 AM EDT Monday for LSZ321-322.
&&

$$

UPDATE...JZ
NEAR TERM...JK
SHORT TERM...JL
LONG TERM...JL
AVIATION...JZ
MARINE...JK


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