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Area forecast discussion 
National Weather Service Gaylord Michigan
700 PM EDT Tuesday may 5 2015

Near term...(this evening through tonight)
issued at 408 PM EDT Tuesday may 5 2015

Overview...mesoscale convective vortex and moisture riding along the stationary front along
the Indiana/Michigan border has moved east, allowing the skies to
clear over north Lower North of M-32, and the trends are for it to clear
for a time north of M-72. However, the 500 mb shortwave ridging is
beginning to build north in the plains, pushing the warm front in
the middle-Mississippi Valley north with more clouds.

The upper Great Lakes for the most part still has the surface high over
the region, and with it a dearth of low level moisture, as the
dewpoints have fallen into the middle to upper 20s f over most of the
forecast area.

Details for tonight...the low relative humidity of today will continue to affect US
overnight keeping the region free of precipitation through the night
as the warm front (currently stationary) moves north into the upper
Great Lakes. However, the surface high is slow to move out of the
forecast area and by 12z is just east of Lake Huron in northeast
Ontario. With the high moving so slowly, low level dry air will be
stubborn to move out of the forecast area, until some time on
Wednesday as the front moves into Michigan. So will have region dry
overnight, with increasing clouds in north lower as the warm front
begins to move north spreading clouds over the upper Great Lakes.
Considering that east upper has been clear all day and that the
moisture will take it's time moving north they could end up clear to
partly cloudy, which would make east upper the best place to the meteor
shower in north Michigan tonight (eta aquariids).


Short term...(wednesday through friday)
issued at 408 PM EDT Tuesday may 5 2015

..warming trend with rain by the end of the week...

High impact weather potential: increased fire danger Thursday.

Pattern synopsis/forecast: split flow pattern across the western
U.S. Merges together over the eastern half of Canada/northeast
quarter of the U.S. In a fast quasi-zonal pattern. Northern branch
upper low impacting British Columbia and the Pacific northwest...
with a southern branch disturbance in The Four Corners vicinity.
Larger upper vortex spinning/expanding out near the dateline will
have implications on our weather down the Road. Closer to
home...surface analysis shows a wavy somewhat stationary front
extending from New England back across the Ohio/middle Mississippi
River valleys and into southeast Nebraska/northwest Kansas. 1028mb
anticyclone centered over northern Michigan pumping dry easterly
flow into the forecast area this afternoon. Meanwhile...return flow
from the Gulf pulling moisture through the plains/Midwest and into
the stationary boundary to the south.

Rising heights over the eastern Pacific ahead of the dateline upper
low will allow northern branch troughing/height falls to expand
south and carve out a mean trough over western North America. This
in turn will kick the southern branch wave out into the plains while
heights rise into the Great Lakes as ridging over the southeast
expands north in response to western troughing. Eventually western
trough splits into two streams again with a slow moving closed low
across California/central Great Basin/southwest by Friday.
Southwesterly upper level winds emanating from around this southern
branch wave will flow across the Great Lakes by week's end. Surface
high pressure will hang on Wednesday as frontal boundary to the
south tips to a more northwest-southeast orientation Thursday before
weakening as stronger thermal gradient well to the north takes over.
Increasing southerly flow begins Thursday as pressures fall across
the plains and Midwest as a cold front pushes east. This front will
eventually reach the upper lakes Friday...but probably remain west
of the forecast area until Friday evening.

Primary forecast concerns: precipitation possibilities along
northward lifting warm front Wednesday...then again ahead of
approaching cold front Thursday night/Friday. Fire weather concerns
through the period. of rain extending from southeast Minnesota/
northeast Iowa east across lower Michigan will be shifting north
tonight as middle level winds back in response to building ridge. Axis
of deeper moisture expected to push into northern lower overnight
into Wednesday...though attendant forcing is weakening with time.
So any leftover precipitation should be thinning with time and not
expecting much in the way of potential quantitative precipitation forecast as band should mostly
dissipate by afternoon and before reaching eastern upper/far
northeast lower. May see some convection try to develop along the
warm front across Wisconsin/Southern Lower Michigan during the
afternoon/evening that may be Worth watching. More sun north/more
clouds south should be how the day sets up...with increasing dew
points relative humidity values should not get out of hand like they
have today with many locales falling below 20 percent. Highs
Wednesday will be dependent on how cloud cover evolves...similar to
today. Temperatures in the upper 60s-lower 70s most likely across
interior eastern upper and the tip of the mitt counties/far
northeast lower Michigan...and possibly along-west of M-37 late in
the day if clouds can thin. Decreasing clouds expected Wednesday
night...with some signals for fog potential but for now will limit
it to lakes Michigan/Huron where advection fog possible as higher
dew points lift north.

Thursday...setting up to be a warm day as southerly flow increases
into Michigan...temperatures expected to push well into the 70s with
a few 80+ degree readings across northern lower. From a fire
weather perspective...temperatures and winds will be near or above
critical values (gusty winds expected with deep mixing). Dew points
in the 50s expected to keep relative humidity values in check...but
will mention elevated fire danger once again for Thursday in the
afternoon hazardous weather outlook. Cold front presses east across
the Midwest Thursday night with a decent southwesterly low level jet
along/ahead of it...along with an attendant Theta-E ridge. So the
threat will increase for some shower/thunderstorm activity pushing
into the forecast area...most likely during the early morning hours.

Friday...cold front moving into the upper lakes on Friday will keep
chances for showers/thunderstorms going...but will be very generic
with this regarding details. Temperatures again will depend on
evolution of cloud cover/precip...could be a warm day again if there
is a substantial break in either (70s to around 80).


Long term...(friday night through tuesday)
issued at 408 PM EDT Tuesday may 5 2015

Extended period models are still all over the place...leaving very
low confidence besides being able to say there will be periods of
rain and possibly storms. As the previous forecaster
all depends on how far the high pressure centered over Ontario
builds into northern Michigan...if at all. If it pushes far enough
south then northern Michigan may see rain and storms Friday night
and Saturday with the frontal passage from a low pressure system
over Hudson Bay...a break from precipitation until the next storm
system approaches from the Central Plains late Sunday night/early
Monday...returning precipitation and storm chances once again. The
second scenario is the high pressure doesn/T extend into northern
Michigan and instead a stalled front extends from the aforementioned
storm system over Hudson Bay to the developing system over the
Central Plains...which could bring an ample amount of much needed
rainfall throughout the entire extended period with slight chances
of thunder as well.


Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 700 PM EDT Tuesday may 5 2015

Conditions will remain VFR through the 24 hour taf period...although
clouds will gradually increase...thicken and lower tonight into
Wednesday morning as a warm front lifts into Michigan. There is a
small chance for showers around tvc and mbl after 12z...but the
chance is too small to include in the taf at this time.
Light/variable winds tonight will become east below 10 kts on


issued at 408 PM EDT Tuesday may 5 2015

Tonight through Thursday...high pressure will once again dominate
the upper Great Lakes tonight, and bring variable winds at 10 knots
or less over the nearshore waters. Wednesday, however, it looks like
the high should begin to move east into the lower Great Lakes. This
will lead to a tightening of the pressure gradient over Lake
Michigan. So will expect the winds to increase slowly during the
afternoon. Winds will continue to pick up on the Lake Michigan side
as the south winds will pick up some momentum from the coastal
convergence in the nearshore waters along the shore of north lower
Wednesday night. By Thursday, the winds may be getting into small
craft criteria, in North Lake Michigan, and Whitefish Bay. On the Lake
Huron side, the winds will be increasing, but will probably remain
below small craft criteria.


Apx watches/warnings/advisories...


Near term...jsl
short term...jpb
long term...tjl

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