Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KDTX 282309
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
709 PM EDT Tue Mar 28 2017


.AVIATION...

Much drier NNE flow has pushed MVFR stratus deck south of terminals
early this evening and generally expect VFR conditions into much of
Wednesday. NE flow across Lake Huron way slowly moisture so will
maintain scattered strato-cu mid morning/early afternoon Tuesday as
moisture is potentially mixed out. Upper clouds thicken in the 18z-
22z time frame, but any notable weather, associated with low
pressure lifting out of the plains, will hold off until after the
forecast period.

For DTW...VFR conditions are expected this forecast period now that
stratus is south of the terminal. Otherwise, NE flow in the 5-7 knot
range will become established into Tuesday around high pressure.

//DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 314 PM EDT Tue Mar 28 2017

DISCUSSION...

12Z Dtx sounding revealed stout low level inversion at 900 MB, which
has been able to sustain clouds thus far with the low level
northeast flow coming off Lake Huron. However, afternoon mixing and
lowering inversion heights is supporting a north-south clearing
tread over the Central Great Lakes, which should continue into the
early evening hours. Weak shortwave trough passing through the
northern Great Lakes early this evening, with cold air filtering in
overnight (925/850 mb temps lowering into negative low to mid
numbers over Lake Huron), which looks to support a redevelopment of
Lake Huron stratus (although significant differences noted in 925 mb
RH fields between nam/gfs/hiresARW/euro), pushing inland during the
day on Wednesday, as differential heating leads to increasing
northeast flow, and potential low/circulation developing (see
regional GEM).

Between clouds and northeast flow off Lake Huron, looks like there
will be a significant range in max temps, from mid 40s across the
far north, to low-mid 50s across the far southwest, farthest removed
from Lake Huron. Once again, afternoon mixing/boundary layer depths
increasing expected to dissipate low clouds late, but warm advection
mid/high clouds should then be on the increase ahead of our next
storm system. Low level thermal profiles will be borderline as
precipitation overspreads southeast Michigan Wednesday Night-
Thursday morning, as it looks like a narrow/700 mb FGEN band could
break out/develop as good surge of moisture takes place, with 700 mb
specific humidity climbing to 5 G/kg by Thursday morning.
Interestingly, the 12z NAM is one of the driest solutions with the
low level dry air holding into Thursday for most of southeast
Michigan. Meanwhile, 12z Euro is one of the more aggressive
solutions in terms of QPF, but 1000-850 mb thicknesses all above
1305 M along and south of I-69 corridor, suggesting all rain. Bottom
line, expecting mainly a rain event as surface temps in the 30s
Wednesday night climb into the 40s on Thursday, but a brief period
of snow is possible late Wednesday night-Thursday morning, mainly
north of M-59 if precipitation rates are sufficiently high enough to
wet bulb/saturate the initially above freezing warm layer (2-6 kft
per NAM soundings). If that narrow but potentially intense 700 mb
FGEN materializes, a narrow swath of wet snow accumulation is
possible for Thursday morning commute, best shot along and north of
I-69 corrdidor, but local SREF weighted probablistic guidance
suggests rain, with low chance of snow north of I-69.

Low pressure pushing east across northern Ohio will bring the
continued chance for rain on Friday as it pushes east into New
England. The chance for rain is expected to diminish through the late
morning and afternoon hours, as a surface high starts to edge in
from the west. The weekend looks to be shaping up to be a nice one,
as cloud cover gradually diminishes and temperatures warm-up slightly
into the mid- 50s for a high. Temperatures are expected to climb
into the upper 50s to lower 60s for the early half of next week as SE
winds usher in milder air.

Low pressure pushing NE from Texas into the Ohio Valley Monday into
Tuesday will bring the next chance for rain. There are slight
variations regarding the track of the low, however, long-range
models are showing convergence regarding precipitation Monday night
into Tuesday. Additional rain showers will be possible as a second
low develops from the Central Plains into Michigan Tuesday into
Wednesday. Confidence is much lower regarding this system as the GEM
holds off on this potential system until late next week.

MARINE...

Existing moderate northerly flow /15 to 20 kts/ over the southern
lake Huron basin will gradually ease tonight as high pressure starts
to build into the region.  Winds will hold from the northeast
through Wednesday as this high settles in.  Wind speeds will remain
more modest during this time.  Winds will strengthen out of the east
beginning Thursday as the region settles between this high pressure
system and approaching low pressure.  A period of moderate winds
will continue through Friday as this low tracks through the Ohio
valley.  The increased gustiness and prolonged onshore flow will
likely result in small craft advisory conditions during this time.
Gusts over the lake Huron openwaters currently expected to peak at
around 30 knots.

HYDROLOGY...

Moisture will expand into the region on Thursday as low pressure
tracks into the Ohio valley.  This will result in widespread
rainfall Thursday and Thursday night.  Rainfall may linger through
early Friday.  At this time, rainfall amounts are forecast to range
between 0.5 and 0.75 inches.  The potential for locally upwards of
an inch will be possible.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

AVIATION.....DG
DISCUSSION...SF/AM
MARINE.......MR
HYDROLOGY....MR


You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.