National Weather Service - Area Forecast Discussion
000
FXUS63 KAPX 190200
AFDAPX
Area Forecast Discussion
National Weather Service Gaylord MI
1000 PM EDT Thu Apr 18 2024
.KEY MESSAGES...
- Rain comes in and moves out tonight.
- Colder/breezy Friday with instability showers.
- Snow showers possible in some areas late Friday night into
Saturday morning.
- Rain shower chances next Monday night and Tuesday.
&&
.UPDATE...
Issued at 1000 PM EDT Thu Apr 18 2024
Upstream cold front now extends from Western Upper Michigan thru
Central Wisconsin into NE Iowa late this evening. Area of light
rain continues to develop ahead of this front...now impacting
the NW half of Lower Michigan. Expect this area of rain will
continues to spread into the rest of our CWA as we head into the
overnight hours...and will then exit from west to east by around
daybreak. Light rain may end with a brief period of drizzle
before ending during the pre-dawn hours. Overnight lows will cool
into the upper 30s to lower 40s.
&&
.SHORT TERM /THROUGH SATURDAY/...
Pattern Synopsis/Forecast: Amplified large scale pattern across
North America and stretching back across the Pacific. One short
wave trough moving away from the Great Lakes today with another
upper low over Saskatchewan/Manitoba that makes up the eastern
portion of a northeast Pacific omega block. Low/mid level cold
air push across the northern Plains/midwest/upper Great
Lakes...850mb temperatures at or below -4C advecting east across
the Dakotas/ Minnesota. Early afternoon surface map shows a
broad occluded low over northwest Ontario...cold/occluded front
arcs south across western Upper/Wisconsin/eastern Iowa.
Widespread clouds northern Michigan at mid afternoon...a
combination of diurnally enhanced Sc and Ac advancing in from
the southwest along with some mid level radar returns across
Wisconsin and central Lower Michigan.
Central Canadian upper low will propagate east through Friday...
passing north of the Great Lakes but there will be some increasing
PV spreading across the forecast area Friday. Associated
cold/occluded front crosses Michigan overnight...with deep layer
cold air advection in its wake.
Primary Forecast Concerns:
Rain comes in and moves out tonight: Axis of deeper moisture and
large scale forcing/frontogenesis ahead of the cold/occluded front
is expected to bring widespread rain chances to northern Michigan
tonight. Should be a quick hitting event...window for precipitation
looks to be about 6-8 hours though there may be some drizzle on the
back end with the front itself. Stability will be weak across
northern Michigan but probably not enough for thunder as better
instability will be over southern Lower and points south tonight.
Highest rainfall potential should be along-east of a CAD-APN line
where rainfall totals by Friday morning of 0.25-0.50+ expected (the
0.50+ should be closer to Saginaw Bay).
Colder/breezy Friday with instability showers: Behind the occluded
front winds will increase from the west and with cold advection/
isentropic downsloping and an increased mixed layer depth should be
able to tap into better momentum aloft. Probability for wind gusts
to 30 mph in the 40-50 percent range across northern Lower and
through the Straits region. Definitely looking at Small Craft
Advisories within most if not all nearshore marine zones. As for
precipitation chances...cold advection will increase instability
across the forecast area but upper level cold pool will settle
across Lake Superior allowing for the potential for deeper diurnal
convective clouds across eastern Upper and the Straits region Friday
afternoon. TQ index values around 17 suggest potential for shallow
convective development...some indications of enhanced convergence
across eastern Upper won`t hurt the cause either. Could see some
graupel/snow mixed in given colder mid level temperatures especially
in heavier bursts of precipitation. Not sure how far south into
northern Lower to pull precip chances with indications of a
shallower convective layer/lower inversion heights. For now have
kept PoPs north of the M-68 corridor.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A broad long wave trough covering much of southwest Canada will
track slowly to the east over the next couple of days. Meanwhile
another trough will drop south out of north central Canada and merge
with the first trough and set up shop across northeast Canada for a
few days. This is all expected to translate into a period of breezy
and mostly below normal temperatures across northern Michigan. In
addition, weak disturbances moving through the flow will bring
occasional chances for showers Friday night into this weekend. It
still looks cold enough for the showers to fall in the form of snow
across parts of eastern upper and the higher terrain of northern
lower later Friday night into Saturday morning (targeting west
northwest favored locals). A light coating of the white stuff would
not be a surprise. Lastly, a Pacific trough then brings rain shower
chances next Monday night and Tuesday. No precipitation is expected
Monday, Wednesday and Thursday.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
A cold front will sweep thru Michigan tonight...producing
widespread rain across much of Eastern Upper and Northern Lower
Michigan. Rain will end from west to east overnight...with just
some lingering scattered shower activity expected across Eastern
Upper Michigan for Friday. Prevailing conditions will be low
VFR/MVFR for the next 24 hours. Light S/SW winds this evening
will become westerly at around 10 kts overnight and will then
strengthen to 15 to 25 kts on Friday.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory from noon Friday to midnight EDT Friday
night for LHZ345>349.
Small Craft Advisory from noon Friday to midnight EDT Friday
night for LMZ323-341-342-344>346.
Small Craft Advisory from noon Friday to 8 PM EDT Saturday for
LSZ321.
&&
$$
UPDATE...MLR
SHORT TERM...JPB
LONG TERM...AJS
AVIATION...MLR
NWS APX Office Area Forecast Discussion
