Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Detroit/Pontiac Michigan
703 am EDT Wednesday Jun 3 2015
Light southeasterly winds will prevail today as high pressure slowly
departs to the east of the region. Some moisture advection from the
southeast will lead to some afternoon cumulus development. There is also
a potential for some low clouds /MVFR/ to develop or advect into the
area from the southeast overnight. Confidence of this occurring is
too low to place a ceiling in the tafs at this time.
//Dtw threshold probabilities...
* low in ceilings less than 5000 feet late tonight and Thursday
Previous discussion...issued 309 am EDT Wednesday Jun 3 2015
Short term...today and tonight
A surface ridge axis will continue to extend across the eastern Great
Lakes into lower Michigan during the short term. The center of the low
level anticyclone over eastern Ontario will slowly move east during
the short term as the middle/upper level flow across the northern plains
and Great Lakes becomes more zonal. This will cause a veering of
the low level wind field toward the southeast today...advecting a
slightly warmer and more moist airmass into the forecast area.
With similar mixing heights expected today as yesterday but with
the low level thermal advection adding a couple degrees to
925-850mb temperatures...daytime highs will nudge upward into the low to
middle 70s. The subtle moisture advection will lead to a little
better afternoon cumulus field over the area. Additionaql moisture
advection will continue into tonight. With surface dewpoints
forecast to rise into the upper 40s to middle 50s and the potential
for some low clouds to advect into portions of the forecast area
from Ohio...min temperatures will be several degrees warmer than the
last couple night.
Light warm advection and slight height rises emanating from the
southwest signal increased column warmth early Thursday as 850 mb temperatures
rise another couple degrees to 12c. This will support highs reaching
78-80f Thursday afternoon beneath a more robust diurnal cumulus field as
middle-level moisture increases around the cutoff low to the southeast.
Confidence is decreased in shower or tstorm potential on Thursday,
so opted to go forward with a dry forecast. Thermodynamic
environment remains poor and forcing is marginal to non-existent.
Only noteworthy signal in the nwp comes from the NAM which develops
erroneously high instability due to high dewpoints and then slams a
lake breeze from Lake Erie into a corridor of of 1500 j/kg MLCAPE
that isn't going to exist. A brief afternoon shower in a region of
inland troughing is not out of the question, but a mention of weather
Thursday into Thursday night is not warranted at this time.
High amplitude ridging over the northern tier will extend well into
central Canada Thursday through Friday, forcing strong high pressure
toward the Great Lakes late Friday. Cold Lakes will allow the lead
edge to attain pneumonia front characteristics as it races through
the County Warning Area from northeast to southwest late Friday. Low chance pop remains
in play here with modest destabilization a possibility in advance of
the front, but lack of larger scale forcing and potential timing
later in the diurnal cycle limit confidence/potential. Best precipitation
potential will remain tied to the low amplitude middle-level
circulation that is currently prognosticated to remain south and west of
the County Warning Area. Temperatures will quickly fall off behind the front, especially if
it passes during Friday afternoon. Lows Friday night fall into the upper 40s
north under cool northerly flow...50s to the south.
Dry forecast remains in play with very low thunderstorm potential
through the end of the week. Winds will remain light into Friday
before building high pressure allows moderate northeast winds to
develop Friday into Friday night.
Lake St Clair...none.
Michigan waters of Lake Erie...none.
You can obtain your latest National Weather Service forecasts online
at www.Weather.Gov/Detroit (all lower case).