Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 261819
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
219 PM EDT WED OCT 26 2016
Moisture advecting into the area will continue to drop ceilings and
visibility to MVFR across Southeast Michigan terminals as low
pressure approaches. A little sleet or snow is possible at MBS, FNT
or PTK before precipitation changes to all rain. Pattern may be
more showery through 20Z at the Detroit-area terminals as drier
air tries to slide northward in advance of the low, before deeper
plume of moisture arrives and allows for more steadier rain and
deteriorating conditions through the afternoon and evening. Drier
easterly flow in the low levels will hold ceilings above IFR
initially, with onset of prevailing IFR conditions a little
uncertain. Potential for IFR will increase steadily through the
very late afternoon and evening. IFR conditions will then prevail
overnight as the low tracks just south of the area before winds
turns north to northwest Thursday morning and some drier air
arrives in the low levels.
For DTW...Deeper moisture will arrive between 19-20Z allowing for
steadier rainfall and higher confidence with ceilings below 2000
feet. Highest potential is for MVFR conditions to prevail into this
evening before IFR ceilings fill in just north of the low track for
much of the night. East winds will continue to favor northeast flow
operations today and tonight as wind speeds remain between 10-15
//DTW Threshold Probabilities...
* High in ceilings below 5000 feet after 20Z.
* High in precipitation type as rain for the remainder of today and
Issued at 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
Lake Huron...Small Craft Advisory until 10 PM EDT Thursday FOR LHZ421-441>443.
Small Craft Advisory until 9 AM EDT Thursday FOR LHZ422.
Lake St Clair...Small Craft Advisory until 4 AM EDT Thursday FOR LCZ460.
Michigan waters of Lake Erie...Small Craft Advisory until 4 AM EDT Thursday FOR LEZ444.
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