Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Detroit/Pontiac Michigan
1143 PM EST Thursday Mar 5 2015


A broad area of surface high pressure will slide toward the Atlantic
and Gulf coasts Friday and Friday night...maintaining favorable
aviation conditions through much of the period. On the backside of
the high...wind speeds will increase Friday afternoon as gusts push
toward 25 knots under thickening high and middle level clouds.

//Dtw threshold probabilities...

* medium confidence in ceilings below 5000 feet Friday night.


Previous discussion...issued 343 PM EST Thursday Mar 5 2015

Short term... afternoon and tonight

An impressive endorsement on the strength of Arctic air in place
over Southeast Michigan today is that nearly full early March afternoon sun
is struggling to lift temperatures out of the teens. A few more
spots in the Detroit area to the Ohio border could surge into the
lower 20s before peak heating runs out...but maximum temperatures across Southeast
Michigan will end up a solid 20 to 25 degrees below normal values
that are around 40 for March 5th.

The Tri Cities will be the only area with any cloud cover by sunset
as a strong diurnal component is indicated in satellite imagery
elsewhere around the region. The evening clearing trend and surface
high pressure settling about directly overhead will allow the wind
to diminish and get temperatures falling rapidly during the evening.
Expect min temperatures to occur around midnight as most locations reach
the single digits below zero...especially in The Thumb where
afternoon readings barely made it into the double digits above zero.
Beside the Detroit metropolitan area...the Tri Cities has the best chance
to stay above zero with the help of clouds during the evening and
then first to see increased southwest wind overnight. The wind will
increase enough to produce a few degrees of upward temperature
response by sunrise but at the expense of wind chill. Expect the
combination of temperature rise and increased wind speed to cross
over a few hours before sunrise and produce wind chill mostly around
10 below zero. A few locations in The Thumb could touch the advisory
threshold of 15 below but this is at the bottom end of the range and
expected to be too brief to warrant a headline.

The relatively warm record low for tonight at dtw is in reach. The
Flint record is at the very bottom end of the range...and mbs will
be comfortably above the record. They are for March 6:

Dtw 2/1901
fnt -7/1960
mbs -8/1948

Long term...

Solid warm advection pattern tomorrow ahead of a cold front...which
will be moving through on Saturday. Strong upper wave tracking
through the Ohio Valley tomorrow will probably temper our higher clouds will likely be prevalent during the
afternoon. Still...with 12z Euro advertising 925 mb temperatures warming to
around -10 c...surface temperatures in the low to middle 20s appear
attainable. Enough warming occurring ahead of the cold front to
prevent Lake Michigan contribution Friday night into Saturday...and
planning on calling for a frontal passage on Saturday with little
fanfare (low chance pops). With enough breaks in the clouds...and
mild start (mid/upper teens) on Saturday...should climb solidly into
the 30s...with potential for locations toward the Ohio border
reaching 40+ degrees as 925 mb temperatures prognosticated to be near zero. Tough
call on mins Saturday night as baroclinic zone hangs up over souther
lower Michigan with weak surface ridge in place and some uncertainty
in exact amount of cloud cover...which will determine if we fall
into teens with the deep snow cover in place vs holding in the 20s
with more extensive clouds. Erred on the mostly cloudy sky side for

A weak shortwave trough will slide across the Great Lakes region
during the day on Sunday. While there is still plenty of uncertainty
in timing and intensity between models with this feature...
confidence is high enough to warrant low chance probability of precipitation /30 percent/
across much of the County Warning Area. Otherwise...beyond Sunday weather conditions
remain quiet and dry as high pressure builds into the region and
remains in place though much of next week. As high pressure
builds...southwesterly winds will allow some warm air advection to
take place by mid-week. This warm air advection will result in high temperatures reaching
into the middle to upper 40s by Wednesday and Thursday.


High pressure tracking through the Ohio Valley tonight with a cold
front swinging into the western Great Lakes tomorrow will produce a
strong southwest gradient over the central Great Lakes region. Ice
cover over majority of Lake Huron will certainly help limit the
potential...but the low level airmass remains very cold...and enough
mixing may occur across the central portions of Lake Huron to
support marginal gales Friday afternoon...but duration also remains
a question mark...and will maintain the gale watch due to the
marginal nature and uncertainty still in play. Weakening pressure
field Friday night and warm advection pattern leading to more stable
profiles causing a drop off in winds during the first half of the
weekend...with light winds expected for second half with a weak
surface ridge arriving.


DTX watches/warnings/advisories...
Lake Huron...gale watch from Friday afternoon through Friday evening for lhz362-

Lake St Clair...none.
Michigan waters of Lake Erie...none.


long term....sf/rk

You can obtain your latest National Weather Service forecasts online
at www.Weather.Gov/Detroit (all lower case).

National Weather Service Glossary of Abbreviations