Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Gaylord Michigan
647 am EDT Wednesday Jul 23 2014

issued at 408 am EDT Wednesday Jul 23 2014

A cooler and much less humid air mass will continue to spread across
the region today as high pressure builds across the western lakes.
This high will remain in control of our weather through the
remainder of the work week...continuing the dry weather. Shower and
thunderstorm chances return for the weekend...with a return to much
cooler weather expected heading into next week.


Short term...(today through tonight)
issued at 408 am EDT Wednesday Jul 23 2014

..early clouds giving way to more sun/much cooler this afternoon...

High impact weather potential: minimal.

Pattern synopsis/forecast: midnight surface/composite analysis shows
a cold front stretching from far northwest Quebec...southwest
bisecting lower Michigan from northeast-southwest...and back across
the middle Mississippi Valley and into Kansas. Drier air filtering
into upper/northern lower Michigan within the Post-frontal air mass
with dew points dropping into the 50s...along with strong low-middle
level cold advection. Broad short wave troughing across the Great
Lakes/Ontario with several embedded smaller vorticity
of which was crossing lower Michigan behind the cold front.
Thunderstorms have cleared northern lower Michigan...with some
stratocumulus (possibly lake enhanced) advecting in from the north.

High pressure centered over Saskatchewan/Manitoba and the adjacent
northern plains states will build east toward the cold advection
maximum across the upper Midwest/upper Great Lakes today. Trailing
short wave trough/pv anomaly over northwest Ontario will slip into
northern Michigan later this evening. Low level thermal trough
settles into Michigan this afternoon (850mb sinking back below

Primary forecast concerns: cover and temperatures
for the most part.

Today/tonight: stratocumulus deck has been more extensive during the
late evening hours..but has shown signs of thinning on the large
scale due to Post-frontal cold advection/isentropic downsloping.
Looks like enough of a temperature differential between the lake and
925mb to support some lake convective component to cloud development
over far northern lakes Michigan/Huron (roughly a line through the
straits). But expect cloud cover this morning to mix into a cumulus
deck (becoming increasingly scattered through the afternoon).
Substantially cooler today than past several afternoons...with highs
in the upper 60s/70s expected.

Mostly clear skies on tap for tonight...winds should end up
decoupling most areas though may take some time across northeast
lower. So should set the stage for another unseasonably cool night
with lows dropping down into the 40s.

Long term...(thursday through tuesday)
issued at 408 am EDT Wednesday Jul 23 2014 extended period of mostly below normal temperatures...

High impact weather potential: minimal. Chances for a few
thunderstorms heading through the weekend.

Pattern synopsis/anticipated evolution: initial zonal flavor to
larger scale noam flow pattern expected to becoming increasingly
amplified as we head into the late weekend and into next week.
Eventual development of Gulf of Alaska low and northeast Canada gyre
say such...with in-between western ridge amplification helping drive
deepening Great Lakes troughing as we head into next week. Current
re-curving far west Pacific typhoon matmo may only help the
downstream amplification cause...perhaps helping deliver another bout
of unseasonably chilly late July weather to the northern lakes. Time
will tell...of course...but a majority of deterministic middle and long
range guidance's...along with their low res ensemble suite...
advertise such changes. Per the usual...above fun often brings about
a period or two of inclement weather...and this one appears to be no
different. Current trough off the West Coast is expected to
sling-shot across the northern Continental U.S. Into the Great Lakes this
weekend...itself helping drive the trough deepening process...
bringing shower/storm chances in the process.

Primary forecast concerns/challenges: temperature trends and
weekend/early next week shower and storm potential.

Details: definitely not too shabby of a start to the extended
period...courtesy of off the deck deep layer dry northwest flow
between earlier mentioned northeast Canada gyre and much lower in
amplitude northern central Continental U.S. Ridging. Surface high is where one
would expect given above upper Patten...settling into and through
our area Thursday into Friday. Clear skies should be plentiful...
with just perhaps some increasing high clouds on Friday. Simple
air mass modification will allow touch warmer conditions Thursday
(when compared to today)...with highs generally in the Lower/Middle
70s. Add in some weak warm air advection processes on backside of departing
high...and should have no problem tacking on a few more degrees for
afternoon readings on Friday.

Highest confidence portion of the forecast comes to a decisive end
heading into the weekend as surface high continues its departure...
all-the-while upstream ridging succumbs to approaching southern
Canada shortwave. Lead vorticity lobe/surge of deep moist advection looks
to potentially drum up some active weather to our west...which
perhaps makes a run into our area Saturday. Like previous forecaster
mentioned...definitely not sold on this idea given flat overhead
regime and main surface warm front remaining off to our south. Of
course...convection will dictate...but could easily see any
organized showers and storms remaining off to south to start the
weekend. Cannot justify removing inherited low end shower and storm
chances...but can find no compelling reason to increase them much
either. Main wave set to arrive Sunday as trough deepening process
kicks into high gear. Shower threat will continue as vigorous
dynamics spread across the northern lakes to end the weekend. troughing expected to dominate Great Lakes weather
heading into the beginning of next week. Pattern easily supports a
return to well below normal temperatures...with highs likely
struggling through the 60s both Monday and Tuesday. Cool overhead
temperatures and additional pockets of energy rotating through
parent trough could bring additional light shower chances just about
any time...but definitely in no hurry to add such detail just yet.


Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 646 am EDT Wednesday Jul 23 2014

MVFR ceilings expected this morning as stratocumulus deck has
spread/developed back into northern lower Michigan...but expect
clouds to mix into a VFR cumulus deck by late morning/early
afternoon. Clear skies tonight.


issued at 408 am EDT Wednesday Jul 23 2014

Will continue with small craft advisories along northeast lower
nearshore well as between Manistee and Sleeping Bear
Point on the Lake Michigan side. Weakening gradient should allow
winds to continue to diminish through the afternoon and into this
evening. As high pressure settles into the upper Midwest for
Thursday winds should remain below advisory criteria though
westerly winds may be a bit gusty through The Straits.


Apx watches/warnings/advisories...
LH...Small Craft Advisory until 5 PM EDT this afternoon for
Lm...Small Craft Advisory until noon EDT today for lmz345-346.



short term...jpb
long term...msb

National Weather Service Glossary of Abbreviations