Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 260710
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
310 AM EDT WED OCT 26 2016
Sharp Upper Level Trough working through the Northern Plains early
this morning, on track to move through the Central Great Lakes
Thursday Morning. Additional shortwave/PV energy diving southeast
through the Southern Plains as well. Upper level Ridge near Four
Corners Region to build during the end of the work week, with some
of the warmer air (850 mb temps 8-12 C) spilling northeast into
Southern Lower Michigan by Saturday. Today looks to be the coldest
day of the week, as temperatures remain stuck in the 40s with a cold
rain developing. Widespread rain still on track, as precipitation
overspreads southeast Michigan with lead moisture advection, 850-700
MB FGEN and isentropic ascent progged lifting through for this
afternoon. Still looks to be close call for some wet snow to mix in
across Tri-Cities region. 00z raob out of dtx indicated an 850 mb
temp of -2 C, with apx also checking in at -2 C, but drier and with
more opportunity to wet bulb. However, with the precipitation
arriving during the daytime hours and strengthening southeast flow
off southern Lake Huron, should be hard pressed to see any snow and
certainly no accumulations with surface temps expected to reside in
the upper 30s.
Model consensus is for low to track along the southern Michigan
border Tonight, as fast moving shortwave/height falls currently
along the southern Alberta/Saskatchewan border merges and tracks
through the Northern Great Lakes on Thursday, helping to draw the
surface low northeast into Eastern Great Lakes. Cold/cyclonic flow
on the backside of the low, with 850 mb temps still progged to drop
to around -4 C. Precipitation chances look to be limited by the Mid
level (700 mb) dry slot rotating through far southern Lower Michigan
Thursday morning. Still gotta believe there is enough moisture down
low with the steep low level lapse rates to support at least
Isolated-Scattered Light Showers, with graupel mixed in still
possible as what little cape in place hovers around zero isotherm.
The weekend forecast remains a bit in flux, but Euro/Canadian/GFS
have converged somewhat with the handling of the upper level energy
off the Pacific Northwest Coast. It now appears a single, stronger
low will be tracking through Friday Night, but well north, over
Ontario. Associated moisture challenged cold front then progged to
clear the State Saturday Morning, but magnitude differences in
amount of cold advection to follow, with the thermal profile issues
lingering into Sunday. Whatever secondary low which tries to develop
from the upper level energy off the California coast is now
forecasted to track through the Ohio Valley and remain rather flat.
At this point, expecting temperatures well into the 60s on Saturday,
with 70+ degrees possible Detroit/South, with high temps falling
back into the 50s for Sunday.
Easterly winds strengthen today downstream low pressure system
ejecting toward the region. Strongest winds expected tonight into
early Thursday as this low lifts across Lake Erie and deepens. Wind
gusts peaking into the 30 knot range over portions of the Lake Huron
open waters during this time. The combination of the gusty
conditions and prolonged onshore flow will result in a period of
small craft conditions along the nearshore waters. These condition
will linger through the duration of the Thursday period, before
conditions ease Thursday night with approaching high pressure.
Widespread rainfall event remains on track from late today through
early Thursday as low pressure tracks across the northern Ohio
Valley. Light rainfall will expand across the area through the
afternoon, before increasing in both intensity and coverage tonight.
The heaviest rainfall will occur through the overnight hours, before
tapering off Thursday. This system will result in a broad area of
rainfall with amounts around three quarters of an inch through
Issued at 1152 PM EDT Tue OCT 25 2016
Low level winds will weaken as they veer easterly during the
morning. This should largely hold the lake strato cu (based in the
3500 to 5000 ft range) close to the shores of Lake Huron and Saginaw
Bay. Light rain will then overspread the region from Southwest to
northeast from late morning into the afternoon. Ceilings will trend
downward during the afternoon under the persistent light rain.
For DTW...There remains at least a low chance that some low clouds
may duct off Lake Huron and brush metro Detroit in the 08 to 11Z
time frame before the flow turns more easterly. There will be a
better chance of a sub 5k ft cloud layer later in the morning as the
winds veer toward the southeast, resulting in a trajectory off Lake
Erie. These clouds will expand during the course of the day as a
region of widespread light rain slowly overspreads the area from
southwest to northeast.
//DTW Threshold Probabilities...
* Low in ceilings below 5000 ft tonight through daybreak Wednesday.
Moderate late Wednesday morning through afternoon. High Wed night.
Lake Huron...Small Craft Advisory from 4 PM this afternoon to 10 PM EDT Thursday
Small Craft Advisory from 4 PM this afternoon to 9 AM EDT Thursday
Lake St Clair...Small Craft Advisory from noon today to 4 AM EDT Thursday FOR
Michigan waters of Lake Erie...Small Craft Advisory from noon today to 4 AM EDT Thursday FOR
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