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Area forecast discussion 
National Weather Service Gaylord Michigan
720 PM EDT sun Apr 26 2015

Near term...(this evening through tonight)
issued at 401 PM EDT sun Apr 26 2015

High impact weather potential: none...unless you count not seeing
the nighttime stars an issue.

One tough sky forecast overnight - that's for sure. Things are
already well in motion for a brief change to our ongoing sunny and
dry weather pattern...courtesy of a pair of rather potent shortwaves
rotating westward around the periphery of closed low pressure
spinning off the southeast Canada coast. The first of those is
dropping through The Straits as I write this at 230pm...delivering a
couple bands of thicker moisture in the form of cloud cover and even
a few sprinkles per spotter reports and radar trends. Outside of
those forced clouds...we have seen a good deal of cumulus flare up
into northeast lower - an indicator that the top of the boundary
layer has already moistened considerably over the past 24 hours
(despite surface dew points still in the 20s).

Meanwhile...a second shortwave is analyzed over Quebec...zipping
westward at a good clip toward the southern tip of James Bay as of
18z. That feature is expected to drop down The Spine of Lake Huron
overnight...helping drag a nice boost of deeper moisture back into
much of the region. By far the deepest moisture looks to skirt
northeast lower and far eastern Upper Michigan...with forecast radiosonde observations
the past few days strongly hinting cloud top temperatures will drop to
around -15c...sufficient to introduce ice into the cloud and perhaps
drop a few scattered showers over those areas...especially near the
Lake Huron shore beneath a core of rather steep middle level lapse
rates. Outside of those areas...low level trajectories will
increasingly tap a quite moist low level airmass to our north...
which has resulted in several bouts of widespread low stratus over
Ontario/Quebec the past few days. Really foresee the same thing
happening for most if not all of northern Michigan later tonight...
as the combo of nocturnal cooling and low level moisture advection
work in tandem. Have to say I wouldn't be shocked even if there was
a touch of drizzle over the higher terrain...and that has been seen
upstream for several days as well. However...given our ambient
rather dry airmass...not quite confident enough to introduce that
mention just yet. Temperatures won't go much of anywhere after falling this
evening...stuck in the 30s for all areas.


Short term...(monday through wednesday)
issued at 401 PM EDT sun Apr 26 2015

..more clouds Monday/few Tuesday and Wednesday with moderating

High impact weather potential: minimal.

Pattern synopsis/forecast: broad upper low over northern New
England/Atlantic Canada extends back across the Great Lakes/Ohio
Valley...narrow ridge axis around the north side of this vortex
extends into the Midwest and plains...while split flow across
western North America finds a new disturbance in the southern branch
over the southwestern states. Overall hemispheric pattern is fairly
progressive despite more blocky/bottled up look to things over
eastern North America. Water vapor imagery shows a couple of
disturbances rotating around the parent low back into northern
Ontario/upper Great Lakes. Early afternoon surface analysis shows a
1025mb high centered over northwest Ontario ridging south into the
Midwest...a cold front lay across western Manitoba/western Dakotas.

Great Lakes will remain under the influence of the downstream upper
low through Monday...with one more short wave trough to drop though
Michigan...before narrow short wave ridging builds into Michigan/
Wisconsin Tuesday. More progressive pattern over the Pacific will
push rising heights into western North America during the first half
of the coming week...short wave energy dropping down the front side
of this ridging will cross the upper lakes in the Wednesday/Thursday
time frame. Northerly boundary layer winds will continue Monday but
weaken Monday night/Tuesday as high pressure builds into the upper

Primary forecast concerns: mainly cloud cover issues into midweek.

Monday...short wave trough will be passing through the lower
peninsula Monday morning...with northern Michigan getting on the
back side of this feature (and synoptic scale subsidence) fairly
quickly. Visible imagery shows a good bit of lower clouds across
the eastern half of Ontario...and this cloud deck will get pulled
down across the forecast area overnight into the day Monday. Expect
that with time clouds will tend to mix into a stratocumulus
deck...and begin to thin a bit during the afternoon hours. Cloud
cover heading into Monday night will depend on degree of this mixing
process during the day...and whether clouds completely melt away or
enough clouds/lingering moisture remain to be augmented by nocturnal
cooling cycle. Suspect the latter idea will will allow
for some clouds lingering into Monday night. This will impact low
temperatures Tuesday could be a pretty chilly night as
winds decouple and where skies can clear. But given cloud
uncertainty will be conservative for overnight lows (mainly in the
30s for now).

Tuesday...narrow short wave ridging will build into the upper lakes
for Tuesday...while short wave energy will be dropping due south
across the upper Midwest. So a quiet day synoptically...with
temperatures warming well into the 50s/lower 60s inland from the
lakes (where onshore lake breezes will predominate).

Wednesday...another short wave trough will move into the upper lakes
for the midweek period...deep layer northerly flow not conducive to
dragging moisture into the the corresponding
precipitation threat is pretty small at this point and will just
carry more clouds closer to forecast short wave track. Should be
another mild afternoon with more highs climbing into the 60s.


Long term...(wednesday night through sunday)
issued at 401 PM EDT sun Apr 26 2015

Models continue to agree with the pattern becoming more progressive
through the extended period. An upper level trough exiting the Great
Lakes region Thursday may produce some rain chances for northern
Michigan early on...but surface high pressure and an upper level
ridge...along with much drier in quickly behind the
departing trough. The aforementioned high pressure will provide
northern Michigan with mostly clear and precipitation-free weather
through Friday. Another area of low pressure...extending from Hudson
Bay to the Central Plains will return periodic chances of
precipitation to the forecast throughout the weekend. Daytime
temperatures will warm a bit each day...beginning with 50s Thursday
and warming to near 70 by Sunday. Overnight temperatures will do the
same...beginning Friday morning in the low to middle 30s and then the
upper 30s to middle 40s by Sunday morning.


Aviation...(for the 00z tafs through 00z Monday evening)
issued at 719 PM EDT sun Apr 26 2015

Ceilings will lower to MVFR tonight as another trough and associated
shot of enhanced moisture swings around the upper trough and into
northern Michigan. A few showers are also possible across portions of
NE lower Michigan (apn). Ceilings will improve to low VFR on Monday...
but expect overall mainly cloudy conditions will hold through much of
the day. Sustained north/northwest winds will hold around 10 kts with higher
gusts expected.


issued at 401 PM EDT sun Apr 26 2015

A passing upper level trough of low pressure will help tighten the
gradient across the waters into the evening hours...with a
subsequent uptick in northerly winds expected for many areas. There
could be a brief period or two where some sites gust to around 25
knots...but don't think it rises to the level of a Small Craft
Advisory...particularly given the lack of any small craft out there
just yet. Winds will remain mainly from the north into Monday but
hold at only 10-15 knots...turning onshore with some afternoon lake
breeze development within a mile or two of the coast. High pressure
looks to drive squarely overhead on Tuesday...with light and
variable conditions under 10 knots...with similar conditions hanging
around into midweek.


Apx watches/warnings/advisories...


Near term...Lawrence
short term...jpb
long term...tjl

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