Area forecast discussion
National Weather Service Detroit/Pontiac Michigan
701 am EDT Sat may 25 2013
Aviation...
//discussion...
Ambient dry air through an impressive depth will keep the door shut
on precipitation chances as midlevel energy passes the state to the
south. The only impact on aviation conditions will be some broken-overcast
ceilings at upwards of 25 kft this morning. Surface winds today are
expected to emerge light northerly commencing on boundary layer
growth. Models are hinting at some cumulus development this
afternoon but that seems suspect at this time.
//Dtw threshold threats...
* none.
&&
Previous discussion...issued 325 am EDT Sat may 25 2013
Short term...today and tonight
Early morning msas analysis is showing a surface ridge extending
southward through the Lake Superior/Michigan/Huron basins. The best
surface ridging component inside of the County Warning Area is across the northern
thumb down into Port Huron. Perusing through the surface
observations...feeling is the best potential for any frost formation
will be in The Thumb and low lying areas of the glacial terrain with
the local office temperature at 33 degrees as of 230 am ldt. Will
maintain the frost advisory as is for simplicity.
There has been a decent radar presentation overnight across portions
of Minnesota/WI/IA tied to the ageostrophic response of merging and
shearing of shortwave energy. One hour precipitation amounts have been
lessening as the precipitation/virga pushes farther to the southeast.
This is likely in response to increasing confluence aloft as the
entrance region lies directly over lower Michigan. The best upper
level forcing in the form of 700-500mb frontogenesis will brush far
southwestern sections of the state between 12-15z...before passing
harmlessly to the south. The amount of ambient dry air in the lowest
12 kft above ground level supports virtually no precipitation potential today. The
preference regarding high cloud forecast lies with the 25.05z RUC which
brings high clouds into the southwestern 2/3rds of the County Warning Area between
9-16z this morning. Increased insolation with some moderation of the
airmass will support a solid 3-8f degree uptick in high temperatures.
Expect readings to range from the middle 50s in the far northern
Thumb/Lake Huron shoreline to the middle 60s Detroit southward.
Surface high pressure will expand across the central Great Lakes
tonight...bringing the prospects of another cool to cold night.
Differential airmass recovery should be good for a few degrees off
this mornings mins. Worked with a blend of undercut guidance with
some persistence. Expected lows tonight should range from the lower
to middle 30s in The Thumb to lower 40s southeast of the terrain.
Long term...Sunday through Friday
Lower Michigan will reside between a high amplitude ridge across the
upper Midwest and a deep upper low lifting from New England into the
Canadian Maritimes during the later half of the weekend...sustaining
a confluent flow aloft. At the surface...this will translate to high
pressure building from the upper Great Lakes on Sunday to the
eastern Great Lakes on Monday. Other than the potential for some
high clouds...skies should remain mainly clear with very dry air
overhead. Temperatures will slowly moderate...leading to an overall warming
trend heading into Memorial Day. Expect mixing depths may
overachieve with plenty of sunshine and substantial low level dry
air. This supports leaning toward the higher end of guidance maximum
temperatures /mid to upper 60s Sunday and around 70 Monday/. The dry
airmass and weak surface gradient will support optimal radiational
cooling potential...so mins Sun night will continue to be quite cold
for late may /upper 30s to middle 40s/.
The middle level ridge is forecast to break down early next weak as
numerous short wave impulses are ejected out of the long wave trough
over the western US and across the central/northern plains. The bulk of the 00z
model suite suggest mesoscale convective system development across the upper Midwest or western
Great Lakes Monday afternoon/night as low level inflow strengthens. The
potential for remnant mesoscale convective system activity to advance into Southeast Michigan remains
highly uncertain at this time. While several model solutions are
quite bullish with quantitative precipitation forecast over Southeast Michigan Monday night and Tuesday...there is
likely some semblance of convective feedback in the models. There is
also concern that the models have a poor handling of mesoscale convective system
propagation...which could lead to remnant convection being much
farther south. Thus plan to carry very low chance probability of precipitation Tuesday.
Persistent low level S-southwesterly flow should however lift a warmer and
more humid airmass into Southern Lower Michigan by middle week...marked by the
passage of a surface warm front. This will justify a chance of
showers/thunderstorms late Tuesday through Wednesday.
The European model (ecmwf) remains steadfast in developing a more amplified upper
trough over the western US by midweek as energy ejects out of the Gulf
of Alaska and into the West Coast. A seasonally strong upper jet
within the base of the deep Gulf of Alaska upper low and current
amplified nature of the flow lends support to the European model (ecmwf). This
solution builds the subtropical ridge farther north into the eastern US
late in the week and suggests Southeast Michigan may be capped. Even the less
amplified GFS builds middle level heights substantially across Southeast Michigan.
Thus the forecast for the later half of next week will have very low
probability of precipitation with maximum temperatures well into the 80s.
Marine...
A stable anticyclone will expand across the Great Lakes through the
Holiday weekend. This weather feature will be responsible for more
typical marine conditions for late may. Wave heights are only
expected to range in the 1 to 2 foot range in many areas throughout
the weekend.
&&
DTX watches/warnings/advisories...
Michigan...frost advisory...miz047-miz048-miz049-miz053-miz054-miz055-miz060-
miz061-miz062-miz063-miz068-miz069-miz070-miz075-miz076-miz082-
miz083...until 8 am Saturday.
Lake Huron...none.
Lake St Clair...none.
Michigan waters of Lake Erie...none.
&&
$$
Aviation.....Cb
short term...cumulonimbus
long term....SC
marine.......cb
You can obtain your latest National Weather Service forecasts online
at www.Weather.Gov/Detroit (all lower case).
