Severe Weather - Flooding

000
ACUS01 KWNS 070542
SWODY1
SPC AC 070540

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1140 PM CST Fri Dec 06 2019

Valid 071200Z - 081200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTHERN CALIFORNIA...

...SUMMARY...
A few strong thunderstorms are possible across portions of northern
California Saturday afternoon.

...Northern CA...

Upper trough off the Pacific coast is forecast to shift east during
the day1 period. As a result, 500mb speed max will translate into
northern CA by 08/00z which should encourage surface confluence zone
across the Sacramento Valley during the afternoon. While the primary
surface front should hold offshore through sunset, some instability
is expected to materialize across the Sacramento Valley due to weak
boundary-layer heating. Latest RAP guidance is more buoyant than the
NAM across this region with forecast instability that could allow a
few robust updrafts.  RAP 23z forecast sounding at BAB exhibits 800+
J/kg SBCAPE with deep-layer shear supportive of rotating updrafts;
although, NAM displays considerably less instability. If surface
temperatures can warm into the upper 50s/near 60F, convection that
develops north of the 500mb jet will have a tendency to rotate. As a
result, a few weak supercells may ultimately evolve which would pose
a risk of producing a brief weak tornado.

..Darrow/Squitieri.. 12/07/2019

$$

000
ACUS02 KWNS 070635
SWODY2
SPC AC 070634

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1234 AM CST Sat Dec 07 2019

Valid 081200Z - 091200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected Sunday.

...Synopsis...
A northern-stream shortwave trough is expected to move across the
northern Rockies into the northern/central Plains on Sunday. At the
same time, a low-amplitude southern-stream shortwave trough will
eject quickly in northern portions of the southern Plains while
another more amplified shortwave trough moves southward across CA.
As a result of this evolution, the overall upper pattern is expected
to undergo substantial deepening and by early Monday morning upper
troughing will likely extend from the Hudson Bay southwestward
through southern CA.

Surface pattern early Sunday will likely feature lee troughing
across the High Plains and high pressure along the East Coast.
Cyclogenesis is anticipated across the central High Plains with the
resulting low moving across northern OK overnight Sunday and into
Monday morning. Modest moisture return is anticipated from the TX
Coastal Plain into the Arklatex, although warm temperatures aloft
should preclude deep convection.

Three different regions have some potential for isolated
thunderstorms. The first is from central CA into the Great Basin
where cold mid-level temperatures will support modest instability
amidst persistent forcing for ascent. Thunderstorm coverage in this
area is expected to be over 10%, which merits delineation of a
general thunder areas.

The second area is across the mid MS Valley where gradually
increasing mid-level moisture and persistent forcing for ascent may
result in a few updrafts deep enough to support lightning. However,
coverage is currently expected to remain less than 10%.

The last area is along the Carolina coast where returning low-level
moisture will help support modest instability. Low-level confluence
within this moist environment will result in showers but updrafts
are currently expected to remain too shallow for charge separation
and lightning production.

...MAXIMUM RISK BY HAZARD...
Tornado:  <2%     - None
Wind:     <5%     - None
Hail:     <5%     - None

..Mosier.. 12/07/2019

$$

267
NWUS53 KAPX 070006
LSRAPX

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GAYLORD MI
706 PM EST FRI DEC 6 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0705 PM     SNOW             EAST JORDAN             45.16N 85.13W
12/06/2019  E3.7 INCH        CHARLEVOIX         MI   TRAINED SPOTTER




&&

$$

JZ

000
FXUS63 KAPX 070735
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
235 AM EST Sat Dec 7 2019

.NEAR TERM...(Today through Tonight)
Issued at 232 AM EST Sat Dec 7 2019

...Temperatures inching upward...

High impact weather potential: Gusty southwest winds tonight to
bring gales to much of northern Lake Michigan as well as more
lakeshore flooding concerns along the Mackinac county coast on Lake
Michigan.

Pattern synopsis/forecast: Well, at least for a little bit longer,
progressive flow regime found across central NOAM...made that way by
dual upper jet cores...one running along the U.S./Canadian border
with the other stretching all the way from Hawaii to the Gulf Coast
States. Split flow regime also noted at the mid-levels, with our
area located under the confluence axis of departing northern stream
troughing and ridging building through the Intermountain West. Weak
warm air advection tied to just as weak mid level impulse within the
northern branch is kicking off a some light snow showers across the
northwest Lakes at this early hour. Otherwise a mostly cloudy and
seasonably chilly night across the Northwoods, with current readings
falling through the lower and middle 20s across much of the area.

Progressive pattern set to continue through the remainder of this
weekend. Warm air advection regime will ramp up considerably,
especially tonight, with deepening southwest flow behind departing
surface high and overspreading of low amplitude mid level ridging.

Primary forecast concerns/challenges: Temperature trends and
addressing some light rain/snow potential.

Details: Passing of that weak upstream wave should be enough to kick
off at least a few snow showers, especially this morning. Most
"concentrated" area of snow showers expected across the Tip of the
Mitt counties up through the Straits with a marginally favorable
over-water thermal gradient within southwest flow regime. Not a big
deal for sure, with most areas seeing less than an inch of snow
(much less than an inch for most).

Southwest flow ramps up considerably going through tonight as area
becomes centered between departing surface high and approach of
developing upstream cold front. Strongest forced ascent on nose of
low level jet expected to remain off to our north, although southern
extent of this enhanced convergence/moisture pooling may just clip
eastern upper Michigan...bringing the threat for a few light snow
showers. Mostly cloudy but dry otherwise. Those increasingly gusty
southwest winds will definitely keep temperatures warmer than this
past night, with readings steady state or even slowly rising after
midnight. Of course, those winds will definitely make it feel
several degrees colder.

&&

.SHORT TERM...(Sunday through Monday)
Issued at 232 AM EST Sat Dec 7 2019

High Impact Weather Potential: Moderate

...Strong winter storm with gusty winds, rain and snow...

Synopsis/Forecast: Southwesterly winds and WAA will be continue
Sunday morning ahead of an approaching cold front. A 45-55 kt LLJ
and gusty southwesterly surface winds will continue to surge above-
freezing air northward over our region. Even with PWATs above 0.5"
(+1 S.D) we may have trouble squeezing rain out of the air mass in
nrn lower through the morning hours. We`ll be within a psuedo-warm
sector with some semblance of a warm frontal boundary to our north.
Better low-mid level moisture resides north of this boundary
(colocated with better dynamics). However, as we progress into the
afternoon a narrow corridor of moisture arrives ahead of the cold
front, increasing precip chances. We`ll stay with rain for nrn lower
as profiles are above freezing for the lowest 2 kft or so. As noted
by the previous shift, the higher terrain nrn lower and perhaps ern
upper may struggle to changeover to pure rain for very long, given a
more shallow surface-based warm layer there. Through the evening
snow gets mixed back in with the loss of any little diurnal heating.
The cold front looks to pass through ern upper before midnight,
before quickly pushing south across nrn lower in the wee hours of
Monday morning.

Also during Sunday night, an upper level wave dives southeast into
the central Plains, spinning up a surface low near Kansas. This low
rides up along the existing cold front through the nrn Ohio Valley
Monday morning. For our area this translates to a shift in winds to
more northeasterly and a brief resurgence of warmer air between
Alpena and Saginaw Bay. In the afternoon forecast soundings have max
omega pegged squarely over a 4 kft DGZ. This will be good for a few
inches in ern upper. Nrn lower may have less accumulation through
the early evening thanks to an isothermal layer near zero for the
lowest 2 to 3 kft, allowing some rain to remain mixed in. Low level
CAA behind the cold front gets better across nrn lower during the
evening, bringing all snow for the entire area. Guidance doesn`t
intensify the low until Monday night, as it crosses into
southeastern Ontario. This is thanks to a favorable exit region
within an intensifying upper level jet stretching from the southern
Plains through the southern Ohio Valley. Winds back through the day,
and become more gusty overnight as the low pulls off to the
northeast.

Overall this system seems a little less impressive than previously
thought, as guidance is weakening and shifting the low farther
north. Snow totals between Sunday night and Monday night look to
remain at 3 to 4 inches or less.

&&

.LONG TERM...(Monday night through Friday)
Issued at 232 AM EST Sat Dec 7 2019

High Impact Weather: Lake effect likely Tuesday into Wednesday.
Some potential for moderate amounts in typical northwest flow
belts.

By Tuesday morning the surface low will be well off to our northeast
with CAA continuing in its wake. 850mb temps drop from the low
negative teens to start the day to near -20 C. Despite great
overlake instability and inversion heights around 5 kft, lack of
better synoptic moisture above the lake generated cloud layer may
throttle back snow amounts. Still a decent set up for lake effect
Tuesdsay into early Wednesday, just not not excited about huge
amounts yet. Wednesday remains the coldest day next week as the core
of Arctic air rotates over us. On Thursday high pressure slides just
to our southeast, giving a break from snow chances, then Friday into
next weekend another clipper system approaches the area.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1046 PM EST Fri Dec 6 2019

MVFR cigs at times, mainly PLN/MBL and perhaps TVC.

High pressure moving into western IL will pass to the south of MI
Saturday morning. Lake effect clouds and snow showers have been
decaying. However, an uptick is expected toward dawn, as a weak
upper level disturbance lends a hand. Some snow showers will be in
the vicinity of MBL/PLN/TVC at times in the morning, and cigs will
ride the border between VFR and MVFR. Cigs will improve later in
the day.

Light winds overnight will become ssw Saturday. Those winds will
be gusty at times in the afternoon evening, and LLWS will develop
late in the evening.

&&

.MARINE...
Issued at 232 AM EST Sat Dec 7 2019

Southwest winds expected to steadily increase across the big waters
today and tonight as pressure gradient ramps up between departing
surface high and approaching cold front. Winds will become quite
gusty tonight into at least the first half of Sunday, especially
across northern Lake Michigan where gales are expected. Small craft
advisories will be needed elsewhere, although will need to watch
areas down near Saginaw Bay where enhanced channeling may tip the
scales to gales. Winds expected to decrease for a time later Sunday
into Sunday night as that upstream front centers overhead and slows
down. More marine headlines anticipated at times heading into next
work week with passing low pressure and the gradual development of
strong cold air advection.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...LAKESHORE FLOOD ADVISORY from 9 PM this evening to 5 PM EST
     Sunday for MIZ095-096.
LH...SMALL CRAFT ADVISORY from 4 PM this afternoon to 5 PM EST Sunday
     for LHZ345>349.
LM...GALE WARNING from 9 PM this evening to 5 PM EST Sunday for
     LMZ323-341-342-344>346.
LS...SMALL CRAFT ADVISORY from 7 PM this evening to 5 PM EST Sunday
     for LSZ321-322.
&&

$$

NEAR TERM...MB
SHORT TERM...STJ
LONG TERM...STJ
AVIATION...JZ
MARINE...MB

317
ACUS11 KWNS 031743
SWOMCD
SPC MCD 031742
MEZ000-NHZ000-VTZ000-032145-

Mesoscale Discussion 2188
NWS Storm Prediction Center Norman OK
1142 AM CST Tue Dec 03 2019

Areas affected...portions of northern NH into ME

Concerning...Heavy snow

Valid 031742Z - 032145Z

SUMMARY...Heavy snowfall with rates of 1-2 inches per hour will
continue to impact portions of northern ME into northern NH through
early evening. The greatest snowfall rates are expected across parts
of central into northern ME.

DISCUSSION...Heavy snow associated with an intense coastal low
offshore of ME will continue to pivot north/northwest through the
21-00z time frame. Strong isentropic ascent is evident in water
vapor satellite loops as the warm conveyor wraps around the
north/northwest sides of the cyclone. Forecast soundings across
northern portions of ME continue to indicate deep, saturated
profiles through the dendritic growth zone. This will aid in
efficient snowfall production, further aided by strong ascent and
warm advection in the 850-700mb layer. The heaviest snowfall rates
are expected from central into northern ME through 21-00z. Farther
west, periods of heavy snow are possible into northern NH, aided by
orographic influences. Though stronger forcing will be shifting east
of this area over the next couple of hours.

..Leitman.. 12/03/2019

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...CAR...GYX...BTV...

LAT...LON   47086780 45746782 45356821 44866882 44466935 44376976
            44257061 44337152 44537157 45077128 45877041 46487018
            46996990 47546929 47526844 47346798 47086780