Area forecast discussion
National Weather Service Detroit/Pontiac Michigan
104 am EDT Thursday Jun 20 2013
Aviation...
//discussion...
High pressure centered over Lake Huron will provide a strong
influence across the region through Thursday night. This will
maintain mostly clear skies and light southeasterly winds during
this time.
//Dtw threshold threats...
* none
&&
Previous discussion...issued 329 PM EDT Wednesday Jun 19 2013
Short term...tonight
Confluent northwest upper level flow will continue to provide
clear/mostly clear skies to the region...allowing for another
another cool night. Surface high pressure (1023 mb) over Lake Huron
will just slowly retreat off to the east. Temperatures today (19z) are
exceeding yesterday afternoon's readings by two or three degrees on
average...and expecting mins about 2 degrees warmer tonight compared
to this morning due to the airmass modification. Also...we do begin
to get into the return flow toward sunrise...which should help
offset the currently low dew points in place this afternoon.
Long term...Thursday through Tuesday
WV imagery shows energy that entered the Pacific northwest is now progressing
eastward toward central California and Nevada where the 500 mb trough
remains...but continues to weaken. East of The Rockies the upper
ridge continues to build and will do so through this weekend.
Surface high pressure will be centered east of the County Warning Area to start
Thursday...but it's influence and the orientation of the low level jet will
still succeed in coaxing a couple surface lows north of our focus
area. Thursday and Friday will be similar to each other with fair weather cumulus
in the afternoon and plenty of sunshine. Temperatures will gradually
increase on Friday as the upper ridge nears and the return flow from
an exiting surface high keeps south winds pumping in warmer and drier
air.
The major forecast challenges and changes start on the weekend.
Models mainly agree that there will be a Stout (590 dam) 500 mb
ridge in place along with warm 18-20c 850 mb temperatures. Mixing from 850 mb
to the surface should get US to the middle or upper 80s. The main
limitation to that is the 1500 to 2000 j/kg of cape and the
potential for an upstream mesoscale convective system tracking into the region. Due to the
conditional nature of convection and the strength of the capping
inversion...will lean towards higher temperatures and lower probability of precipitation for
Saturday. Sunday looks like a better chance to hit 90 as the upper
air setup is very similar...except there will be an even stronger
cap in place. Dewpoints will be near 70 and cape values will again
be in the 1500-2000 j/kg range so the potential for strong to severe
thunderstorms is certainly there.
Monday will be continued hot and muggy with storm chances under a
similar pattern to the weekend. Flow turns more zonal or trough-like
on Tuesday with only slight moderation to the temperature and
dewpoints. Though we may fall short of a definitive heat wave...we
will likely see heat index values over 90f for 4-5 days. Adding to
the high heat threat is a recovery only to 70f or so each night.
Marine...
High pressure over the central Great Lakes will be slowly sliding to
the east. Light southerly winds tomorrow into the weekend will allow
warmer and more unstable air to move into the area...allowing for a
chance of showers and thunderstorms....especially on
Saturday.
&&
DTX watches/warnings/advisories...
Michigan...none.
Lake Huron...none.
Lake St Clair...none.
Michigan waters of Lake Erie...none.
&&
$$
Aviation.....Mr
short term...sf
long term....mm
marine.......sf
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