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Area forecast discussion 
National Weather Service Gaylord Michigan
948 PM EDT Thursday Aug 27 2015

issued at 948 PM EDT Thursday Aug 27 2015

No big changes needed to the forecast.

Sprawling surface high pressure is centered over the eastern lakes
down into the Ohio Valley this evening...holding off the slowly
advancing short wave/deeper moisture axis and attending showers in
the Midwest and plains. Abundant cloud cover across the County Warning Area through
the afternoon has rapidly diminished this evening...except for
one remaining thin line of clouds across interior northern lower
Michigan...possibly caught up within the residual inland thermal
trough. That batch of cloud cover appears to be slowly fading and
pushing eastward.

Rest of tonight...have tweaked sky forecasts to account for the
remaining interior clouds...which should slowly fade and fan out
into NE lower Michigan over the next few hours. After that...low
level S/SW flow will increase just a notch overnight. Guidance
continues to suggest that residual low level moisture off to our
south might get cycled back toward the region overnight...and
manifest itself as an expanding stratus deck into parts of the
area. Tough call...but with that in mind have continued with the
idea of having increasing clouds back into eastern Upper Michigan
late (off the lake) as well as nudging up cloud cover for parts of
northern lower Michigan toward morning.


Near term...(this evening through tonight)
issued at 252 PM EDT Thursday Aug 27 2015

..decreasing clouds this evening with some patchy fog possible...

High impact weather potential: minimal.

Pattern synopsis/forecast: surface high pressure was centered over
the Great Lakes at middle afternoon...with last bit of low level
thermal troughing to the east/south of the forecast area.
Stratocumulus deck slowly breaking up across northern lower...with
more sun across eastern Upper. Pocket of drier air resides across
Michigan above the low level cloud layer.

Surface high will build into the lower lakes/middle Atlantic tonight...
while low pressure slowly works east across the Central Plains.

Primary forecast concerns: cloud trends and fog potential.

Tonight...expect clouds to continue to thin through the late
afternoon/early evening...though some residual clouds may stick
around northeast lower for a while. During the overnight hours...
developing southwest flow over Lake Michigan and some lingering low
level instability may allow for some more clouds to develop and push
into parts of eastern upper and far northwest lower. Meanwhile...a
period of clearing skies and light winds combined with still modest
temperature-dew points spreads may allow for some patchy fog to
develop. Overnight lows will depend on cloud cover...but can see
some 40s across parts of north Central/Northeast lower.


Short term...(friday through sunday)
issued at 252 PM EDT Thursday Aug 27 2015

High impact weather potential: none

Primary forecast concerns/challenges: addressing Friday afternoon
through Saturday shower potential.

Convectively induced shortwave moving out of the plains on Friday
with weak/moisture starved front sliding toward the northern lakes
out of Canada. These two systems present a challenge with regard to
rain chances Friday afternoon into the models continue
to struggle with how these waves may /or may not/ interact with each
other. A majority of the gefs members keep the waves
separate...which results in the best forcing/moisture sliding south
of our area with southern wave. On the flip side...a few of the
deterministic model members show more phasing and bring a "beefier"
area of low pressure across the northern lakes with widespread rain.
Honestly...difficult to have much confidence in either solution at
this time as there just isn/T enough clear consensus either way.
But do believe that the most likely scenario takes the heaviest rain
south of our area associated with southern shortwave...with much
lighter and spottier rain chances further north. Rain will be on
our doorstep on Friday...although will struggle to push east into
northern lower until later in the day with initial relatively dry
lower levels of the atmosphere. Best rain chances come Friday night
into the first half of Saturday. Will add isolated thunder to the M-
55 corridor on Saturday with marginal instability and skinny cape
resulting in the possibility of a few rumbles of thunder.

Temperatures likely just a bit below normal on Saturday /especially
south/ given the expected clouds...but readings will hinge almost
entirely on the eventual rain trends.

Sunday...the overall trend should be toward drier conditions. Still
some disagreement in the deterministic model members in the exact
evolution of upper level energy over the Great Lakes and how quickly
upstream ridging builds eastward. But consensus solutions push low
pressure eastward and begin to fold upper ridge into the Great
Lakes. Outside of a shower threat early over southeast
areas...Sunday will be dry with warmer temperatures.


Long term...(sunday night through thursday)
issued at 252 PM EDT Thursday Aug 27 2015

Monday through Thursday...a large area of high pressure centered
over the eastern two thirds of the country...will remain nearly
stationary through the forecast period. At upper levels...a 500mb low
centered on the Great Lakes during the weekend will slowly exit east
Monday...allowing a strong upper ridge to build over the Ohio Valley
and Great Lakes. The pattern should generate mainly dry conds across
northern Michigan through the period. Middle level temperatures will warm through the
period in the strengthening ridge (850mb temperatures around 14c Monday
warming to 20c thursday)...forcing afternoon highs well above normal
into the middle and upper 80s for the upcoming work week.


Aviation...(for the 00z tafs through 00z Friday evening)
issued at 617 PM EDT Thursday Aug 27 2015

Scattered-broken VFR ceilings still lingering out there but will quickly fade
through early evening with loss of daytime heating. Bigger
forecast challenge revolves around possible stratus redevelopment
during the overnight hours. Guidance suggests as low level S/SW
flow picks up later tonight...lingering low level moisture gets
shoved back into northern Michigan and might manifest itself as an
expanding stratus deck into Friday morning.

Any stratus that does develop will mix out quickly Friday morning
and solid VFR conditions are anticipated.


issued at 252 PM EDT Thursday Aug 27 2015

Tonight/Friday...winds will begin to pick up from the south/
southwest tonight...which will continue into Friday. Small craft
conditions are not anticipated.

Outlook...expect backing winds to a more east/southeast orientation
for Saturday. Headline conditions not expected through the weekend.


Apx watches/warnings/advisories...


near term...jpb
short term...keysor
long term...swr

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