Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/09/19
AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
643 PM EST Sun Dec 8 2019
.SYNOPSIS...
A weak area of low pressure lifts north across eastern North
Carolina late tonight and off the Mid Atlantic coast on Monday.
A stronger area of low pressure tracks across the Great Lakes
late Monday and into eastern Canada on Tuesday. A trailing
strong cold front crosses the local area Tuesday night. High
pressure returns for Wednesday and Thursday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 355 PM EST Sunday...
Latest sfc analysis shows 1032 mb high pressure offshore of New
England. Meanwhile, an inverted trough was developing just off
the Southeast coast. Moisture in the form of increased cloud
cover has begun to spread into southern VA as of 3 pm, with
overcast conditions now prevalent from the Hwy 460 corridor on
south. Clouds will continue to overspread the region from south
to north through sunset, becoming overcast/mostly cloudy
everywhere this evening. Rain will also be advancing north from
eastern NC and latest HRRR has the pcpn reaching southern
portions of the FA by around 00Z. The coastal trough/weak sfc
low will organize over the eastern Carolinas later this evening
and then models move the wave of low pressure N across eastern
NC late tonight and then NNE to near the northern OBX/Va Beach
by 12z Mon. This will result in a decent slug of moisture
overspreading most of the area overnight, but with emphasis on
areas along/east of the I-95 corridor. Will have likely PoPs for
much of the FA by 06z tonight and then likely/categorical PoPs
from 06z-12z Mon. QPF amounts overnight will be under 0.50",
except local amounts up to 1" possible for coastal NE NC. Temps
will be higher tonight, but still chilly across the Piedmont
given in-situ wedge setup. Lows from the mid 30s NW to the low
50s SE coast.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
As of 355 PM EST Sunday...
The weak low quickly exits to the NE and offshore Monday morning
as SW flow aloft begins to increase in response to broad mid-
level troughing across the upper Midwest. Models do show a punch
of drier air working in across southern/SW portions of the FA by
late morning into the afternoon. Will have lowest PoPs for
these areas through the day. Farther N/NW, plentiful moisture
present will coincide with mid-level energy rotating in from the
NW to result in likely PoPs through the day. Milder Monday with
winds becoming SSW in the afternoon. However, wedge conditions
will still take a while to erode across the Piedmont so the
temperature forecast may be a bit tricky. Highs Monday will take
until late afternoon/evening to reach the mid 50s NW and around
60 for the I-95 corridor. Highs should reach the mid/upr 60s SE
VA/NE NC in the afternoon. Mot much of a temp drop Monday night
with SW flow and WAA in place ahead of a cold front crossing
the OH/TN valley. Additionally, pcpn chances will be on the
decline. What we may have to contend with Monday night is
widespread low stratus or potential dense fog given moist low-
levels. Will continue to monitor this potential and adjust
forecast accordingly. Lows Monday night from the low 50s NW to
the low 60s SE.
Models continue the slower trend of pcpn arrival on Tue ahead
of the approaching cold front late Tue/Tues night. Latest data
suggests little support for pcpn thru 18Z (except low chc PoPs
Piedmont) with PoPs gradually increasing from west to east
through 00Z Wed. Thus, adjusted the grids with this trend in
mind. Will have likely PoPs N/W late Tues lowering to slight chc
PoPs across NE NC prior to 00Z Wed. What this does is allow
for is an unseasonably warm day (not quite to record levels,
see CLI section below) with partial sunshine possible across
the east and a breezy SW wind. Highs will range from the mid/upr
60s Piedmont to the low/mid 70s east (upr 60s/low 70s Eastern
Shore).
Cold front crosses the area Tuesday night with
likely/categorical PoPs through 12z, then decreasing PoPs from
west to east on Wednesday as the cold front exits offshore.
Likely PoPs (55-70%) areawide in the morning, then lingering low
chc PoPs (~30%) for coastal areas after 18z. It will turn
sharply cooler again Tuesday night into Wednesday. Lows Tues
night in the mid 30s NW to the mid 40s SE. Highs Wednesday from
the low 40s NW to the low 50s SE. Believe the best chance of
seeing any frozen pcpn will remain N/W of our local area late
Tuesday night/Wednesday morning, so have kept p-type all liquid
for now. Total QPF amounts through Wed will be on the order of
0.50-1", except locally higher amounts across eastern NC that
receive the most rain tonight.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 355 PM EST Sunday...
Strong high pressure over the upper Midwest will build into the
region Wednesday night. Strong cold advection on northwesterly winds
will lead to overnight low temperatures in the low to mid 20s NW,
mid to upper 20s for the I-95 corridor, and upper 20s and low
30s for SE VA and NE NC. The aforementioned surface high will
become centered over/just north of the local area on Thursday
with decreasing clouds and winds. Daytime high temperatures will
only make it into the upper 30s and low 40s on Thursday. Models
have come into much better agreement and all now keep the area
dry on Thursday and Thursday night. Chilly overnight lows range
from the low 20s NW to upper 30s SE.
Surface high pressure continues its eastward migration on Friday but
will still extend ridging to the SW along and east of the higher
terrain. GFS/ECMWF solutions diverge regarding timing for the
expected wet period late week into the weekend with the GFS around
12 hours faster than the ECMWF. Will increase PoPs slowly from the
south/southwest during the day on Friday but the bulk of the precip
is expected to fall Friday night into Saturday as low pressure lifts
northward across the region. Given the slower timing, high pressure
will have moved well away from the favored area to supply cold/dry
air to the region and concerns for mixed precipitation have
decreased. High temps on Friday range from the low 40s NW, close to
50 degrees for the Richmond metro, and low to mid 50s for areas east
of I-95. Not looking particularly cold behind the weekend system
either, highs in the 50s Saturday and Sunday with lows in the upper
30s and low 40s.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 640 PM EST Sunday...
VFR conditions in place but will quickly degrade this evening
and especially tonight as low pressure and associated rain and
lower CIGs creep northward from the Carolinas. Trend in model
guidance has been for a slightly faster degradation in flight
categories and will show a fairly quick transition to MVFR and
IFR this evening at RIC, slightly later for more eastern sites
tonight. Fog is also a concern at RIC Monday morning. Rain will
exit to the east and offshore by 09.12Z, perhaps a bit later at
SBY. IFR conditions will hang on into Monday afternoon before
CIGs finally begin to lift. Winds out of the SE tonight will
become S and SSW by late in the period with gusts ~20 knots
possible at ORF and ECG.
OUTLOOK... The area will be largely rain free from Monday
afternoon through Tuesday morning. However, localized reductions
in CIGS/VSBYS will be possible, especially Monday night, due to
areas of fog/stratus. Periods of lower CIGS/VSBYS in both
rain/shwrs are likely Tues aftn through Wed morning, as low
pressure tracks well to our NW. A trailing cold front will cross
the area Tues night. High pressure builds into the area for
Wednesday/Thursday.
&&
.MARINE...
As of 400 PM EST Sunday...
High pressure has moved well off the coast this aftn with a
sfc trough developing off the SE coast. E winds avg 5-10 kt in
the Bay and northern coastal waters, and 10-15 kt across the
southern coastal waters. Seas are 2-3 ft N and ~4 ft in NC
waters. Bay waves are 1-2 ft. Have raised SCA headlines late
tonight/Mon AM for the coastal waters as the sfc trough
gradually lifts N and SE winds increase along the coast. The
strongest winds are progged to stay a little offshore, but even
if winds only gust to ~25 kt, seas are expected to build to 4-6
ft overnight and to 5-8 ft later Mon into Tue. Less confident at
winds increasing to SCA thresholds over the Bay/sound/Rivers and
local wind probs are only ~10-30% for this occurring during the
day Mon so have held off and will generally have S winds to
around 15 kt on Mon (winds will tend to be lighter early Mon for
the Bay and especially the Rivers as the front is slow to lift
to the N/NW).
Increasing SSW flow should bring winds to ~20kt in the Bay/sound
Mon night so headlines will probably be needed but this is
currently 3rd period so will allow next shift to adjust as
necessary. With very warm conditions Tue during the day ahead
of an approaching cold front, winds over the cold waters will
likely diminish a bit (though seas on the coast will remain at
or above 5 ft). SCA conditions likely for all zones Tue
night/Wed AM as colder air moves in from the N. Potential for
stronger winds Wed night/Thu as a secondary cold surge arrives
with strong high pressure building in from the N while low
pressure lingers over the SE CONUS. Seas will also remain
elevated through this period.
&&
.CLIMATE...
Record highs for 12/10:
RIC...79 in 2007
ORF...78 in 2007
SBY...73 in 1966
ECG...78 in 2007
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory from 7 AM Monday to 6 PM EST Tuesday for
ANZ650-652-654.
Small Craft Advisory from 1 AM Monday to 6 PM EST Tuesday for
ANZ656-658.
&&
$$
SYNOPSIS...JDM
NEAR TERM...JDM
SHORT TERM...JDM/MPR
LONG TERM...RHR
AVIATION...JDM/RHR
MARINE...CMF/LKB
CLIMATE...
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1001 PM EST Sun Dec 8 2019
.SYNOPSIS...
A light wintry mix will impact the southern Adirondacks
tonight, as clouds thicken and lower for the rest of the region, as
a low pressure system approaches from the Mid Atlantic Region. The
low pressure system and a frontal boundary will bring mainly rain to
the forecast area tomorrow into Tuesday with milder temperatures and
breezy conditions. Colder air moves back into the region with a
period of snow possible from the Capital District and Berkshires
south and east late Tuesday night into Wednesday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Winter Weather Advisory 11 pm EST to 8 am EST for the
southern Adirondacks...
Updated at 945 PM EST... Conditions remain dry across the
forecast area this evening with clouds gradually lowering.
Current temperatures range from the mid 30s at ALB where a gusty
channeled southerly wind is blowing, to the mid 20s over more
sheltered areas. Expecting a general upward trend in
temperatures overnight but exact values will continue to depend
on the wind speed with areas that maintain light winds remaining
below freezing for most of the night. Spotty, light freezing
rain or drizzle can still be expected late tonight over the
southern Adirondacks as southerly flow will be upslope into that
area. Meanwhile, steadier rains will approach the mid-Hudson
Valley from the south by daybreak. Previous discussion is below.
Updated at 645 PM EST... Current forecast is on track. Mostly
mid and high level cloudiness spreading across the area early
this evening with temperatures near freezing and dew points well
down into the teens to lower 20s. Latest 18z NAM nest still
showing the development of some spotty light freezing rain over
the Adirondacks later tonight with increasing isentropic lift
and upsloping southwesterly flow developing across that area.
The last few runs of the HRRR are not as agressive with this
developement, but overall the idea that a little very light and
spotty freezing rain could develop over the Adirondacks around
or just after midnight still seems reasonable. Temperatures may
fall another couple of degrees this evening, but will be rising
into and through the 30s overnight. Previous discussion is
below.
As of 400 PM EST...High pressure continues to move well east of
New England tonight, as broad southwesterly flow will occur in
the low to mid levels associated with the mid and upper level
trough centered over the northern and central Plains. A series
of short-waves embedded in the southwest flow will impact the
region. One disturbance ahead of a cold front over the northern
and central Great Lakes Region will focus a light wintry mix for
the southern Adirondacks. A combination of the isentropic lift
and orographic enhancement off the southwest Adirondacks will
generate some light sleet and freezing rain, as temps will
likely bottom out early this evening, and then slowly rise. The
temps in the Hudson River Valley may not fall much due to a
strong low-level jet and the funneling effect due to the
retreating sfc anticyclone and the front to the west.
Also, a southern stream disturbance will be lifting northeast
from the Carolinas. This wave of low pressure forming will
enhance the isentropic lift for some light rain or showers to
move in late south and east of the I-90 corridor. The Capital
Region may stay mainly dry tonight with breezy conditions. Lows
will be early on in the 20s to lower 30s, and then rise
overnight. Clouds will be thickening and lowering. Some of the
winds gusts this evening could get to 20-35 mph especially over
the confluent region of the Capital Region and into the Upper
Hudson River Valley.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
Tomorrow...Any spotty freezing rain or drizzle should transition
to plain rain over the southern and eastern Adirondacks,as temps
rise above freezing. The temps should rise east of the southern
Greens, but if they do not, then an SPS for spotty freezing rain
or a WSW maybe needed. We leaned toward a superblend and warmer
temps with the strengthening south to southwest flow.
The low-level jet increases with the latest 12Z GEFS indicating
+v-wind anomalies /southerlies/ of 1 to 3 STD DEVs above normal
with PWATS increasing to +1 to +3 STD DEVs above normal. The
sfc wave will be lifting northeast for periods of rain. It
should be noted the H850 moisture flux anomalies will be in the
+3 to +4 STD DEVs above normal, so some moderate bursts of rain
are likely especially south and east of the Capital District.
The southwest flow aloft will tend to shunt the pcpn over the
Capital Region due to shadowing off the Catskills. Temps will
be rising to the 40s with some spotty 50s over the mid Hudson
Valley and perhaps near Bennington, VT. The snowpack will begin
to ripen and absorb the initial surge of rainfall.
Monday night...Temps continue to rise and steady in the lower
40s to lower 50s. The surface dew points are likely to rise
into the upper 30s to mid 40s, which means the combination of
temperatures and dew points could lead to enhanced snow melt,
along with the locally moderate to heavy rainfall and patchy
fog. Some of the guidance shows a lull in the pcpn after 06Z
with the wave moving east of New England. The cold front will be
approaching from western and northern NY by daybreak on Tuesday.
Tuesday...The cold front slides across the region with one more
surge of rain or showers. There is a strong thermal gradient
for a transition to some snow over the southern Adirondacks in
the afternoon. Max temps will be in the late morning and early
pm, but then temps will fall due to the strong cold advection.
Max temps will be in the 40s to mid 50s and then fall in the pm.
Some light snow accums are possible in the southern Adirondacks.
Total QPF before night fall may be in the about half an inch to
local amounts of 2.0 inches. See the hydro section for the super
specific details.
Tue night...The cold front slows and acts like an ana front
with moisture pooling northward behind the sfc front and wind
shifts axis. Temps will be dropping quickly in the 20s to lower
30s with teens in the southern Adirondacks. The low and mid
level FGEN increases with a weak wave ejecting northeast from
the Delmarva. Periods of light to moderate snow may break out
from the eastern Catskills/Capital Region and the Berkshires
south. We may need advisories for the southern
Taconics/Berkshires/NW CT and it could be a sloppy morning
commute from the Tri Cities south and east. Lows in the teens
and 20s with wet snow accums of 1 to 3" (highest totals in NW
CT and the southern Taconics/ prior to daybreak from ALY south
and east. See the long term for more details.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Intrusion of arctic air with below normal temperatures will dominate
the beginning of the long term forecast, followed by some moderation
in temps, along with the next prospects for precipitation associated
with a possible coastal storm by next weekend.
A wave of low pressure developing along a frontal boundary to our
south and east should allow precipitation to linger across southeast
areas Wednesday morning. Forecast thermal profiles suggest P-type
should be snow. The question is how much precipitation occurs from
mid level forcing and moisture, as some southern stream energy
translates northeastward. Latest 12Z/08 deterministic and ensemble
model guidance suggests the possibility of at least a few additional
inches of snow across portions of the mid Hudson Valley northeast
into NW CT, the southern Berkshires, and southern Taconics, although
can not rule out precipitation lingering farther north in the
morning, which could allow some snow closer to the Capital Region of
NY into the northern Berkshires. Stratiform precipitation should
taper off by afternoon, however arctic front and main upper level
trough passage should promote snow showers and perhaps embedded
squalls for the afternoon/evening hours, especially for the Mohawk
Valley northward. High temps mainly in the mid 20s to mid 30s, with
temperatures possibly falling during the afternoon hours.
Snow showers should transition to more of a lake effect/enhanced
event Wednesday night through Thursday morning, initially favoring
the southwest Adirondacks and western Mohawk Valley, before shifting
southward and becoming more multi-banded during Thursday morning,
with areal coverage likely decreasing in the afternoon as a
subsidence inversion lowers with high pressure building closer.
Otherwise, quite blustery with Wed night lows in the single digits
and teens, and highs Thursday mainly in the teens and 20s, although
could approach the lower 30s in the mid Hudson Valley. Wind chills
look to drop to zero to 10 below across northern areas, and zero to
10 above elsewhere Wednesday night.
High pressure should bring fair but cold conditions for Thursday
night into Friday night, with lows Thursday night dropping into the
single digits above and below zero across northern areas, and teens
elsewhere, with some potential for pockets of temps dipping to -10 F
or lower across the southern Adirondacks, depending on cloud cover
and wind. Highs Friday mid 20s to lower 30s.
Lots of uncertainty regarding next possible storm system for late
Friday night into next Sunday, with most likely period of
precipitation next Saturday. Siding closer to 12Z/EC for onset
timing based on past performance. Thermal profiles look relatively
warm aloft, so this could be a rain/ice (rain/freezing rain)
situation, depending on how much shallow low level cold air remains
across the region. Will have to watch trends through the week. Lows
Friday night and Saturday night in the mid 20s to low 30s, although
may be warmer depending on ultimate storm track, with high
temperatures in the mid 30s to lower 40s.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
VFR conditions expected through most of tonight at all TAF
sites although clouds will be gradually lowering. Scattered
showers will develop after 11z along with MVFR cigs, then steadier
and more widespread rain and showers will develop after about
15z. Conditions will continue to lower through the day and into
Monday evening with mainly IFR cigs and vsbys expected Monday
night in low clouds, fog and showers.
Winds will be from the south at speeds ranging from 10 to 20 kts
with a few higher gusts at ALB, to less than 10 kts at POU and
GFL. Southerly winds will average 10 to 20 kts at all of the TAF
sites Monday afternoon and Monday night.
Outlook...
Monday Night: High Operational Impact. Breezy Definite RA...FG.
Tuesday: Moderate Operational Impact. Likely SHRA.
Tuesday Night: High Operational Impact. Likely SHRA...SHSN...SN.
Wednesday: Moderate Operational Impact. Chance of SHSN.
Wednesday Night: Moderate Operational Impact. Scattered SHSN.
Thursday: Low Operational Impact. Isolated SHSN.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: Low Operational Impact. NO SIG WX.
&&
.HYDROLOGY...
Temperatures will remain below normal tonight into early
tomorrow, so little melting and/or runoff is expected on the
weekend. This will allow the snow pack to be maintained and
unripened. Temperatures will likely rise to above normal
values tomorrow and continue into Tuesday, with periods of rain
likely. There is increasing confidence that temperatures and
dewpoints will rise into the mid 30s to lower to mid 40s late
Monday afternoon through Tuesday morning, especially along and
south of the Mohawk Valley to southern VT. Those temperatures
and dew points along with locally heavy rain could enhance snow
melt.
There is uncertainty with the amount and placement of the
heaviest rain, however our current forecast is for about a half
an inch to about two inches in the HSA with the highest totals
in the southeast extreme over the Housatonic Basin in NW CT, the
southern Greens, and also in the west/southwest Adirondacks.
MMEFS guidance varies with the NAEFS and GEFS suggesting some
rivers reach action stage and perhaps and isolated stem nicking
minor flood stage and the SREF suggesting some rivers reaching
minor flood stage. Uncertainty in the amount of snow melt and
where the heaviest rain will fall is why there is such a variety
of solutions in the sources of guidance.
The bottom line, none of the NERFC forecasts are projecting
flooding at this time. Some ripening and melting of the snowpack
and runoff is expected, although widespread flooding is not
anticipated at this time. Rises on area waterways are likely
during this timeframe.
It will turn sharply colder Tuesday into Wednesday and continue through
the end of the week, which should put a stop to any melting/runoff,
and allow river levels to recede. Light to moderate snow amounts
are possible Tue night into Wednesday from the Capital Region
south and east in NW CT and the mid Hudson Valley.
For details on specific area rivers and lakes, including latest
observed and forecast river stages and lake elevations, please visit
the Advanced Hydrologic Prediction Service /AHPS/ graphs on our
website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Winter Weather Advisory until 8 AM EST Monday for NYZ032-033-
042-082.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Wasula
NEAR TERM...MSE/Wasula
SHORT TERM...Wasula
LONG TERM...SND/KL
AVIATION...Speciale
HYDROLOGY...NAS/Wasula
Area Forecast Discussion
National Weather Service Boston/Norton MA
913 PM EST Sun Dec 8 2019
.SYNOPSIS...
High pressure offshore will start a flow of increasingly milder
and more moist air overnight. Showers will develop around
daybreak and will turn into a soaking rain Monday into Tuesday,
along with strong southwest winds in southeast Massachusetts
and on all coastal waters. A cold front moves through Tuesday
night, ushering in much colder air that will likely change rain
to snow and linger into Wednesday with accumulations possible.
Cold and dry into Friday before temperatures begin to moderate
Friday night. Next system brings a period of rain by the
weekend, with temperatures trending above normal.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
915 PM Update: No significant changes.
Southerly flow is underway which has helped temperatures begin
to rise, especially near coast, which will be trend overnight.
Warm advection has also led to development of low clouds near CT
Valley, as moisture has become trapped beneath inversion. High
res guidance indicates these clouds will become more widespread
overnight across interior, before spreading toward coast around
daybreak.
Still looks like any showers will hold off until around sunrise,
which is supported by HRRR and to some degree 00z NAM.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
*** Periods of moderate to heavy rain ***
345 PM update...
Monday ...
Strong thermal and moisture advection ahead of approaching short
wave with 925 mb winds increasing to 60-70 kt. This results in PWATs
surging to about 1.25 inches by end of the day. This synoptic scale
lift combined with anomalous moisture advection will yield periods
of moderate to heavy rain. This strong low level WAA results in
surface dew pts rising into the low 50s across eastern CT/RI and
eastern MA. These high dew pts combined with plenty of SSW wind
should yield appreciable snow melt and combined with moderate to
heavy rain at times, expecting lots of standing water for the late
day/evening commute. Thus hydroplaning could become a concern. These
increasing dew pts streaming over the snowpack will also increase
the probability of patchy dense fog.
Strongest wind gusts up to 30 mph will be over southeast MA where
dew pts climb into the low 50s and easy low level inversion. Inland
with dew pts only the 40s should be enough of an inversion to keep
winds 20 mph or less.
As for thunder, not expecting much if any given lack of elevated
instability/poor mid level lapse rates.
Monday night ...
*** Periods of Moderate to Heavy Rain Likely ***
Periods of moderate to heavy rain continue thru the evening as
robust mid level short wave moves across the area and accompanied by
60-70 kts of SSW flow at 925 mb and advects PWATs up to 1.4 inches
across RI and eastern MA. This strong low level WAA results in
surface dew pts continuing to surge into the low and mid 50s. Thus
more snowmelt combined with periods of moderate to heavy rain during
the event will continue to yields lots of standing water on area
roadways.
SW winds could gusts up to 40 mph over southeast MA including Cape
Cod and the Islands. This strong low level WAA pattern will result
in temps remaining in the 50s overnight! These increasing dew pts
streaming over the snowpack will also keep the risk of patchy dense
fog.
Short wave moves east of the region second half of the night with
weak short ridging building across the area. Thus a downward trend
in precip is likely after midnight.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
345 PM update ...
Highlights...
* Cloudy but mild Tues with another round of showers mainly late day
* Rain early Tues nite changes to a period of accumulating snow
(potentially plowable in interior and urban corridor) overnight
into Wed. Increasing confidence for adverse impact to Wed AM
commute.
* Cold and dry Wed nite through Fri. Moderating temperature and
moisture levels Friday night.
* Next system for the weekend, with rainy conditions and above-
normal temps.
Details...
Tuesday:
In the wake of expected rains Monday night, weather pattern remains
unsettled for Southern New England. Most of the region will be the
warm sector and a cloudy one at that. Will keep chances for showers
going through the first part of the day, but tried to focus highest
PoPs into the Likely range more tied with the cold front, which
approaches our western counties late Tuesday. Cold frontal precip
should prove much less than the rains for Monday/Monday night, with
additional QPF of a quarter inch or less. Highs mid/upper 50s to
near 60.
Tuesday night into Wednesday:
Colder air rushes southeastward Tuesday night, and as at least
sheared-out mid-level vort max ripples northeastward from the
central Appalachians, will be looking at rain changing to wet snow
on the cold side of the cold front.
Did note more ECMWF Ensemble members indicating snow for Tuesday
night into Wednesday than 24 hours ago, with ensemble probabilities
for 3" or more of snow in the 24-hour period 18z Tue - 18z Wed now
up to 50% across western MA/western Hartford County, the hills in
central MA and Tolland County eastward into the northern Providence
suburbs. Recent trends in the GFS have also trended snowier in this
period. Global models show anomalously strong mid and upper level
jets (~ 100 kts at 500 mb, 150 kts at 250 mb, with Southern New
England positioned in the favorable equatorward entrance region of
each jet), and there are hints in the guidance at some bands (axis
of 850 mb -EPV, some though unfocused FGen @ 850) during the
overnight hrs.
What remains uncertain is the timing of the changeover, forecast
liquid-equivalent precip and the northwestern extent of accumulating
snows. Each of the above factors renders confidence in snow
accumulations at low to moderate levels. Did note that most models
have again increased QPF in this period, though there may be a sharp
cutoff in precip N/W of the Mass Pike and especially north of
northern MA/Route 2 corridor. WPC`s Day-3 accumulation seems fairly
reasonable as far as a first-cut at accumulations goes.
In spite of stated uncertainties, do think confidence is increasing
in potential for an adversely impacted Wednesday morning commute for
at least a part of the region, especially across the central part of
the interior (Hartford/Springfield, Worcester/Providence into the I-
95 corridor). This is roughly where axis of greatest liquid-
equivalent QPF seems to lie, though some variability in models
exists to be re-evaluated with forthcoming guidance. Pavement`s also
apt to be wet at onset and sharply colder temperatures filtering
that could freeze this before or during the period of accumulating
snow, the potential for slippery travel into the AM commute remains
a possibility.
Wednesday Night through Friday Night:
1040+ mb high becomes anchored across much of New England. Quite
chilly and dry through Thursday night with 850 mb temps in the -10
to -15C range. Will show highs in the 20s to near freezing, with
lows in the teens. A few single digit lows are possible across
northern MA.
Southerly warm advection pattern commences Friday into Friday night
as high pressure shifts into the Canadian Maritimes. Temperatures
and moisture levels should begin to recover. Will see increased
clouds into the nighttime hrs Friday night, and while the GFS brings
in warm frontal precip late, likely too dry to support PoPs higher
than low Chance.
Saturday into Sunday:
Weekend remains unsettled with the next chance of significant precip
by the weekend, though models continue to deviate on timing. As
mentioned, the GFS brings rain in as soon as Friday night, while the
ECMWF is more into late Saturday into Saturday night, and the
Canadian GEM is still slower than the ECMWF. Could be a decent rain
maker for most of southern New England, with another round of gusty
southerly winds across the waters.
A return to above-normal temps looks likely for the weekend with 850
mb temps rising into the mid/upper single digits Celsius. Will show
highs in the upper 40s to mid 50s with clouds and rain likely
accompanying the warmest temps, though potential for even warmer
with cloud breaks.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Monday Night/...High confidence.
02Z TAF Update:
MVFR CIGS near CT Valley will gradually spread across interior
overnight, but probably don`t reach coastal sites until 10-12Z.
Monday ... MVFR with embedded IFR especially inland. Periods of
rain, moderate to heavy at times. LLWS 020/19045kt. Surface
winds south at 10-15 kt. Areas of fog will restrict vsbys in
the MVFR/IFR category.
Monday night ... A mix of MVFR/IFR in periods of rain, moderate
to heavy at times. Areas of fog too. Rain possibly tapering off
after 06z. LLWS 020/19050kt
KBOS Terminal...High confidence in TAF trends, lower confidence
on exact timing details.
KBDL Terminal...High confidence in TAF trends, lower confidence
on exact timing details.
Outlook /Tuesday through Friday/...
Wednesday: Mainly VFR, with areas IFR possible. Breezy. Chance
SHSN.
Wednesday Night through Thursday: VFR. Windy with local gusts
up to 30 kt.
Thursday Night through Friday: VFR. Breezy.
Friday Night: Mainly IFR, with areas MVFR possible. Breezy.
Chance SHRA, chance FZRA, slight chance SHSN.
Saturday: Breezy. Chance SHRA, chance FZRA.
&&
.MARINE...
Short Term /through Monday Night/...High confidence.
345 AM update:
** Gale Warning Continues late Monday/Monday Night **
Tonight ...
1030+ mb high pressure over Georges Bank continues moving seaward
overnight. Gradual increase in SSW winds. Dry weather and good vsby
thru midnight but then risk of showers toward daybreak.
Monday ...
SSW winds increase to gale force late in the day along with building
seas. Areas of dense fog develop possible in the afternoon along
with milder conditions. Periods of moderate to heavy rain limit
vsby.
Monday night ...
SSW gales continue with periods of moderate to heavy rain during the
evening along with areas of dense fog possible. Vsby may improve
after midnight as rain moves offshore and SSW winds become more SW.
Outlook /Tuesday through Friday/...
Wednesday: Winds less than 25 kt. Local rough seas. Rain
showers likely, snow showers likely. Local visibility 1 to
3 nm.
Wednesday Night: Moderate risk for Small Craft Advisory winds
with local gusts up to 30 kt. Areas of rough seas.
Thursday: Moderate risk for Small Craft Advisory winds with
local gusts up to 30 kt. Local rough seas.
Thursday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft.
Friday: Winds less than 25 kt. Local rough seas.
Friday Night through Saturday: Low risk for Small Craft
Advisory winds with gusts up to 25 kt. Rough seas up to 12 ft.
Chance of rain showers.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Gale Warning from 6 PM Monday to 6 AM EST Tuesday for
ANZ231>235-237-250-251-254>256.
Small Craft Advisory from 4 PM Monday to 6 AM EST Tuesday for
ANZ230-236.
&&
$$
SYNOPSIS...Nocera/Loconto
NEAR TERM...JWD
SHORT TERM...Nocera
LONG TERM...Loconto
AVIATION...JWD
MARINE...Nocera/Loconto
Area Forecast Discussion
National Weather Service Quad Cities IA IL
533 PM CST Sun Dec 8 2019
...00Z AVIATION UPDATE...
.SYNOPSIS...
Issued at 255 PM CST Sun Dec 8 2019
GOES 16 satellite imagery has shown a train of clouds filtering in
across the region today. Most of these has been high in nature, but
several observations across northeast Missouri have shown an
increase of low clouds over the last hour. These were all building
north ahead of a cold front draped from the UP of Michigan to
southeast South Dakota. As of 2 PM, temperatures across our area
ranged from 40 in Dubuque, to 53 in Macomb, continuing the trend of
nice and pleasant mild weather we`ve seen over the past few days.
However, temperatures were only in the low to middle 20s in western
Minnesota and northern South Dakota behind the front. This front and
a developing surface low will be the main driver of our weather
concerns for the short term period.
&&
.SHORT TERM...(This Evening through Monday Night)
ISSUED AT 255 PM CST Sun Dec 8 2019
Key Messages:
1) Rain and drizzle coverage to increase early tonight.
2) Areas of fog expected beginning around midnight, especially along
and north of Interstate 80.
3) Cold front will pass through late Monday morning, bringing
increasing winds, falling temperatures and rain changing to snow.
Tonight...
All deterministic guidance is in good agreement of the evolution of
our system this evening through Monday, leading to a high confidence
forecast.
Weak and broad area of surface low pressure is progged to develop
over central Oklahoma this evening, and will quickly track northeast
along the slow moving cold front. As it does so, moisture transport
across the Midwest will increase, helping to further saturate the
low-levels of the atmosphere. Enough lift is expected to occur ahead
of the low with a renewed surge of WAA, leading to some increase in
precipitation chances. Forecast soundings continue to hint a fairly
insufficient depth of moisture, with a fairly potent dry layer
expected to cap it around 800 hPa. This would favor more drizzle vs
actual rain showers, and will help to keep QPFs limited roughly to a
few hundreths. Some rain showers will be possible further east and
southeast where more sufficient lift is expected.
The other concern for overnight is potential for areas of dense fog.
Surface winds will decrease with the approach of the surface low. In
addition, surface convergence will also increase in moisture rich
low levels as the low passes directly overhead, leading to an
environment favorable for areas of fog. High res guidance such as
the HRRR and HREF has remained fairly consistent on this occurring,
with the focus of reduced visibilities primarily along and north of
the Interstate 80 corridor beginning around midnight. After speaking
with surrounding offices, have decided for now to hold off on a
dense fog advisory as confidence remains low to medium, but this may
change over the course of the evening.
Monday through Monday Night...
Any fog across the area should slowly dissipate over the course of
the morning as convergence decreases with the low passage. In
addition, we will have a brief lull in the precipitation before the
front arrives by late morning. Once it does, winds will shift and
increase out of the northwest, with gusts near 30 MPH possible
during the afternoon and evening. There will also be a renewed
chance of precipitation along and behind the front. What should
start as rain initially will begin to mix with and change to all
snow as the front passes and colder air filters in. Thankfully, not
much in the way of QPF or snow amounts is expected as this will be a
fairly quick mover. Much of the region will actually be dry by the
evening.
The main story with the front will be temperatures. Highs for the
day should occur during the morning before temperatures start
falling behind the front during the afternoon. By the evening,
temperatures will approaching 20 degrees across our northwest CWA,
with wind chills dropping into the single digits! Lows Monday night
will range from the upper single digits near Waterloo and
Independence, to upper teens over Macomb, Princeton and Burlington.
Thankfully, this period of cold will be brief, and will only
continue into the early portion of the long term period.
.LONG TERM...(Tuesday through Sunday)
ISSUED AT 255 PM CST Sun Dec 8 2019
Tuesday and Wednesday
A cold and dry air mass will be in place over the Midwest as a
1030mb high slides overhead. Model blend max temps are about 10
degrees below normal for mid December, and range from near
freezing in the far south to the upper teens far north. Overnight
lows will be cold, in the teens (and single digits north), but
would be much colder if we had an extensive snow cover.
There is a chance for light snow to impact parts of the area
Tuesday night into early Wednesday morning, along a zone of tight
850mb baroclinicity and associated isentropic lift and
frontogenesis. Models aren`t in very good agreement with the
ECMWF/CMC generating light QPF and the GFS/NAM mainly dry. For
now, added slight chances to the forecast, roughly along/north of
I-80. If the wetter models verify, which is still only low QPF,
some light snow accumulations are possible with the cold ground
temps expected by this time.
Thursday On
The arctic high will shift into the Eastern U.S. for late this week,
which will cause surface winds to increase out of the south leading
to a period of warm air advection. High temps will respond, reaching
into the 30s on Thursday and upper 30s to mid 40s on Friday.
A low tracking along the U.S./Canadian border will drag a cold
front through into Friday night, bringing a chance for light rain
and snow. Overall, this system should be relatively weak.
Into next weekend, forecast confidence is low regarding chances
for snow across eastern Iowa and northwest Illinois. Models vary
quite a bit on the timing and strength of a few shortwave troughs
forecast to pass through the Central U.S. Due to the low
confidence, only have low chances for precip at this time. Model
blend temps trend colder through the weekend, falling to near or
slightly below normal by Sunday. Uttech
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
ISSUED AT 533 PM CST Sun Dec 8 2019
Conditions will deteriorate from MVFR to IFR tonight as low
clouds, fog and light precipitation develop ahead of an
approaching cold front. Precipitation will be mainly in the form
of drizzle, developing after midnight with surface temperatures
holding well above freezing through the night. Confidence in the
timing of the onset of IFR conditions is low at this time, but
likely in a window between 08z and 12z. The potential for dense
fog looks to be greatest at DBQ. Monday morning, the light winds
will increase and become gusty from the west to northwest as the
cold front pushes through. This front should also bring ceilings
improving to MVFR. There will likely be a period of rain or snow
showers with the frontal passage, which has been included with
prob30 groups at the end of the period at CID, DBQ and MLI.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...Speck
SHORT TERM...Speck
LONG TERM...Uttech
AVIATION...Sheets
Area Forecast Discussion
National Weather Service Grand Forks ND
956 PM CST Sun Dec 8 2019
.UPDATE...
Issued at 951 PM CST Sun Dec 8 2019
An area of 700 mb frontogenesis remains along the band of heavy
snow between Grand Forks and Fargo. Heavy snow and low visibility
remains possible in this band. More widespread light snow to the
north and south the the heavier band continues to produce reduced
visibility across eastern North Dakota, northwest and west central
Minnesota. Look for the snow to move southeast tonight into Monday
morning. Snow ratios continue to be on the high end above 20:1
ratios based on snow reports. The main impacts continue to be
blowing and falling snow making travel difficult.
UPDATE Issued at 704 PM CST Sun Dec 8 2019
With warm moist air moving over the area and a region of 700 mb
frontogenesis heavy snow has been reported in band moving across
eastern North Dakota and northwest Minnesota. For this reason
Winter Storm Warnings and Winter Weather Advisories have been
expanded to the north. Heavy snow in Grand Forks has been observed
with snow ratios in the 25:1 to 35:1 range. This heavy snow band
will move to the south overnight into Monday morning. When in this
band visibility may fall to around 1/4 of a mile along with gusty
winds and heavy snow. Travel will be very difficult as this band
moves through.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 335 PM CST Sun Dec 8 2019
A baroclinic zone with associated surface frontal band which
stretches across North Dakota and northern Minnesota is steadily
intensifying as cold air advection at mid levels and below
increases. RAP analysis shows an H7 trof axis starting to swing
through the western Dakotas, while 21z GOES 16 RGB imagery shows
multiple low to mid cloud layers arcing through western into
central ND... coincident with increasing radar returns and surface
observations. Light snow is showing in surface observations across
much of the Devils Lake and mid to upper Sheyenne River Basins in
eastcentral ND.
SPC mesoanalysis indicates some potential for a brief period of
freezing drizzle or sleet yet this afternoon in southeast ND, but
with strong sfc to mid level cold advection occurring would expect
any mixed precip to change quickly to snow. Otherwise there is a
possibility of some elevated and/or slantwise convection across
south central and southeast ND as well, with a heavier banded
snowfall potential mainly from southeast ND into west central MN.
Expect snow to continue spreading eastward and intensifying
through the evening and overnight hours as the associated mid
level trof swings southeastward though the area. NAM12 and RAP
guidance show the mid lvl trof axis passing through the southern
RRV by 15z, which should mark the end of appreciable snowfall
there... with some lingering light snow into northcentral MN
through 18z. Surface pressure gradient and cold advection will
support moderate northerly surface flow at 15 to 20 kts across
eastern ND and the central RRV corridor into mid morning on
Monday, with winds and snowfall slow diminishing as the system
passes.
Mondays high temperatures may be near midnight tonight, and in the
low single digits, with temperatures steady or falling through the
day. Expect some partial clearing around midday on Monday, but
bitter wind chills approaching minus 20F throughout the day.
.LONG TERM...(Tuesday through Sunday)
Issued at 335 PM CST Sun Dec 8 2019
Colder Arctic air settles over the region as the upper level trof
sags southward. A reinforcing cold shot Tuesday night into Wednesday
keeps temperatures suppressed...with highs near zero and lows in the
mid teens to 20 below zero. With persistent northerly winds...lowest
wind chill values will remain in the 30 below zero range.
For Thursday...the upper level low situated near Hudson Bay shifts
eastward and the upper ridge begins to amplify in the west. Surface
high pressure shifts east into the Ohio Valley...and return flow
behind the ridge will see warmer air advance north into the area.
By Friday...northwesterly flow aloft becomes more zonal. A few
impulses are forecast to propagate through the flow bringing
occasional chances for snow. With a lack of moisture to work
with...expect any precipitation that falls to remain on the light
side.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 704 PM CST Sun Dec 8 2019
The main impact for this TAF period will be the band of heavy snow
moving across the Northern Plains. When in this band of heavy snow
VLIFR conditions will be present. After the band moves out lower
ceilings and visibility will persist into Monday morning.
Conditions will improve from west to east Monday morning into
Monday afternoon. The worst conditions are mostly over for DVL and
will end by around 0200 UTC for GFK. Most impacted will likely be
FAR with IFR to VLIFR conditions tonight and tomorrow morning. IFR
conditions are the most likely worse conditions for TVF and BJI
this evening into Monday morning.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Winter Storm Warning until 9 AM CST Monday for NDZ039-053.
Winter Weather Advisory until 6 AM CST Monday for NDZ014>016-024-
026>030-054.
Winter Storm Warning until 6 AM CST Monday for NDZ038-049-052.
MN...Winter Storm Warning until 9 AM CST Monday for MNZ002-003-
022>024-027>032-040.
Winter Weather Advisory until 6 AM CST Monday for MNZ001-007.
Winter Weather Advisory until 9 AM CST Monday for MNZ008-009-
013>017.
&&
$$
UPDATE...NC
SHORT TERM...Gust
LONG TERM...Hopkins
AVIATION...NC
Area Forecast Discussion
National Weather Service Marquette MI
710 PM EST Sun Dec 8 2019
.SHORT TERM...(This evening through Monday)
Issued at 337 PM EST SUN DEC 8 2019
Forecast is still on track for moderate snow accumulations Monday
over northwestern Upper Michigan, but there have been some forecast
changes today for minor to perhaps moderate accumulations of
freezing drizzle tonight into tomorrow.
As of 18Z this afternoon per RAP analysis, a sfc trough and cold
front are currently draped across Upper Michigan from approximately
Michipicoten to Iron River. Colder air will continue to filter in
through tonight, but currently saturated lower levels are not cold
enough for ice nucleation so drizzle has been reported at CMX and
observed here at MQT. Current sfc temps are above freezing for most,
but have already dipped below 32F at CMX and this trend will
continue south and east. Similar conditions are likely over western
and north-central locations through this evening. As winds turn to
the N and then NE and 850mb temps cool to -7 to -9C, onshore and
upslope favored locations like northern MQT/Baraga and western
Gogebic counties, the spine of the Keweenaw, and the Porkies will
have the best chance for a light glaze of ice accumulations late
this afternoon and evening.
Temperatures will cool aloft enough that ptypes will transition to a
mix of -fzdz/-sn and then eventually isolated to scattered -shsn
northwest of a line from LNL to MQT tonight. For many locations over
the southeast half, the column will not cool enough for any -sn
until sometime during the day Monday, so areas of -fzdz/-fzra are
expected through tonight. Given the potential for minor ice
accumulations, perhaps as high as a tenth of an inch in portions of
Marquette and Alger counties, have opted to start the Winter Weather
Advisory at 00Z to cover this threat before widespread snow moves in
Monday morning.
Monday: As a deep upper trough approaches from the northwest, a sfc
low will develop to our south and push to near Drummond Island by
00Z Tuesday. An area of strong fgen and modest qvector convergence
will move in from the west during the day. With deeper moisture to
accompany this forcing moderate snow is expected to develop, first
near IWD prior to sunrise and then spreading across Upper Michigan
through the day. Northeasterly winds will lead to lake
effect/enhancement east of the Keweenaw in the morning but as they
back to the north in the afternoon the western UP will get some lake
help as well. As mentioned earlier, ptype over far southeastern
portions of the area may not become all snow until midday, so some
light ice accumulations remain possible prior to 18Z. In terms of
snow ratios, total QPF, and snow accumulations, little change has
been made to the forecast though snow totals were bumped up slightly
in higher terrain with max amounts of about 8" possible by 00Z
Tuesday.
.LONG TERM...(Monday night through Sunday)
Issued at 356 PM EST SUN DEC 8 2019
The current quasi-zonal mid/upper level pattern will become more
amplified this week as a ridge builds along the West Coast with a
deep downstream trough from Hudson Bay into the north central CONUS.
This will allow Arctic air to plunge into the Great Lakes with much
below normal temperatures by the middle of next week. Moderation is
expected toward the end of the week as the colder air lifts into
eastern Canada and flow again becomes more zonal with milder Pacific
air moving into the region.
Mon night, the shortwave which will be responsible for the
widespread snow on Monday will be lifting east of the area by late
evening as model soundings show strong subsidence/drying behind it.
This should taper off LES over the north to northwest wind snowbelts
after 1-2 inches of additional snow accumulation into the early
evening hours.
Tue-Thu morning, Much colder air will move in as CAA strengthens
from Tue into Tue night. Models fairly consistent showing 850 mb
temps dropping to around -25C by Tue night into Wed morning which
will favor moderate to heavy LES for what looks like the w-wnw wind
Lake Superior snow belts Tue night into Wed. Highs Wed will only
reach into the single digits over the interior west and the low
teens east with double digit below zero readings expected over
interior portions of the west Tue night and Wed night. Wind chill
values could also approach advisory criteria (around -25) late Tue
night into Wed morning for a few spots over the interior west half.
Thu-Sun, Models indicate the pattern deamplifying toward the end of
next week with the mid-level trough and cold Arctic air lifting into
eastern Canada and a more moderating Pacific zonal flow setting up
across the northern Conus and Upper Great Lakes region. Models hint
at a few shortwaves moving through which could bring chances for
some light snow late Thu into Fri. Plenty of differences and
inconsistency in deterministic models for next weekend regarding
evolution and track of storm into the Great Lakes region. The 12Z
GFS solution is the most bullish indicating sharp deepening of a mid-
level trough over the central CONUS and the phasing of the northern
and southern jet streams for the potential of a significant storm
developing over the central Great Lakes next weekend. Meanwhile, the
12Z ECMWF shows phasing taking place much farther east developing a
nor`easter over the Mid-Atlantic and New England states. The GEFS
ensemble members show a widespread range of solutions with some of
the members lending support to either the 12Z GFS or the farther
east 12Z ECMWF solution. Nonetheless, model trends will need to be
monitored regarding this system for next weekend, but for now, chc
pops will be warranted for light snow on Saturday and then lingering
LES behind the system into Sunday. Expect high temps toward the end
of the week (Fri-Sat) to rebound closer to normal with readings into
the upper 20s to lower 30s, but then cooling off slightly behind the
system on Sunday back into the 20s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 658 PM EST SUN DEC 8 2019
Conditions overnight into tomorrow will deteriorate as moderate
to potentially heavy snow moves into the terminal areas. KIWD will
likely be the first terminal to see the reduced visbys, expected
to continue through much of the morning hours, and have captured
as much of this anticipation as possible in a tempo group.
However, have held off on tempo groups for KCMX and KSAW, but may
very well also need to be added for the next TAF issuance. Look
for any lingering freezing drizzle to end at KIWD as the night
progresses, due to a cold, more moist airmass moving in. As the
steadier snow moves in tomorrow, look for ceilings to lift a
smidge, despite the anticipated further reduction of visbys.
Winds initially for this TAF period will remain out of the NE to
ENE, becoming more NNE during the day tomorrow. Blustery winds may
cause snow to blow around, adding to any potential reduction in
visbys.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 356 PM EST SUN DEC 8 2019
North winds increasing to 25 to 30 knots across west and central
Lake Superior this afternoon behind a frontal passage will spread
across the rest of the lake by evening. Not out of the question that
there could be a few gale force gusts along and immediately behind
the cold front across the north central into this evening. Tonight
through Monday morning, winds become northeast between 20 and 30
knots, with the strongest winds expected to funnel down the western
arm of the lake into the Duluth area. By mid-day Monday, winds
remain 20 to 30 knots, but winds start to become northerly as a low
pressure system tracks lifts northeast across lower Michigan.
As this low tracks over Lake Huron Monday night, Arctic air will
spill across the lake with north to northwest winds between 20 and
30 knots and a few gale gusts to 35 knots. Expect this colder, more
unstable airmass to linger across the lake through the end of the
week. Tuesday through Wednesday, winds will predominately be
westerly, between 20 and 30 knots. A few gale force gusts cannot be
ruled out at times Tuesday through Wednesday, especially on higher
platforms. This sharply colder air mass will also allow moderate
freezing spray to develop after the initial cold front passage early
on in the week. As much colder air works down on Wednesday, it
continues to look like heavy freezing spray will develop. Winds
diminish a bit (generally into the 15 to 25 knot range) from
Thursday into Friday and back more southerly as a high pressure
ridge moves over the area.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Weather Advisory until 10 PM EST /9 PM CST/ Monday for
MIZ001>006-009-084.
Winter Weather Advisory until 7 PM EST /6 PM CST/ Monday for
MIZ010>013.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...KCW
LONG TERM...Voss
AVIATION...lg
MARINE...Voss
Area Forecast Discussion
National Weather Service Tucson AZ
753 PM MST Sun Dec 8 2019
.UPDATE...Increased the shower threat over western Pima county and
added a slight chance for thunderstorms through Monday.
&&
.SYNOPSIS...A Pacific weather system will bring periods of rain and
higher elevation mountain snow into Monday. Much cooler temperatures
will also occur Monday followed by cold temperatures Monday night
behind the departing system. Dry conditions with a warming trend will
then prevail Tuesday into next weekend.
&&
.DISCUSSION...Light precipitation is beginning to develop across the
forecast area this evening and is doing so a bit further west than
our grids would suggest. A couple of showers have some decent
intensities well to our west and there has even been a lightning
strike or two. SPC has much of the area in a general thunderstorm
threat tonight and I concur as MUCAPE is in excess of 250 to our
west and NW. Model soundings indicate that CAPE values will run from
200-350 through Monday so I gradually spread the slight chance of a
T-storm to much of the area by mid-day Monday. Other than that just a
few minor tweaks. Updated forecasts already sent.
&&
.AVIATION...Valid through 10/00Z.
BKN-OVC clouds 7k-12k ft MSL through the forecast period with lower
cig heights at times. Expect intermittent periods of light rain at
all terminals, increasing in coverage and becoming moderate at times
Monday. There may be an isolated thunderstorm or two through the
period. In rain, MVFR ceilings will be possible tonight, with brief
IFR possible Monday. Light westerly winds tonight will become
southwesterly to northwesterly 8-15 kts Monday. Strongest winds
expected to be at KDUG. Aviation discussion not updated for TAF
amendments.
&&
.FIRE WEATHER...Minimal fire weather concerns. A weather system is
expected to impact the area through Monday night with a chance of
valley rain and mountain snow. Dry conditions return Tuesday morning
and continue through the end of the work week. 20-ft winds will
generally remain less than 15 mph through the forecast period.
&&
.PREV DISCUSSION... /issued 308 PM MST Sun Dec 8 2019/
Deeper subtropical moisture from the Pacific is bringing a few light
showers to the area this afternoon, ahead of a low currently digging
south into central and southern California. This feature will remain
engaged with higher latitude support and easily kick across Arizona
Monday. With the cold pool tracking directly through southern Arizona
and the best available moisture fields, our corner of the state will
probably be featured for this particular system.
Light showers will continue into tonight with precipitable water
values just under 1 inch in the warm sector ahead of the low. Snow
levels will remain above mountain peaks for the time being. As the
low pushes into southwest Arizona Monday morning, we`ll start to
lose some of that moisture with modest drying in a dry slot
wrapping under and into the eastern flank of the low. However,
dynamics and shear will make up for that with a solid convective
band advertised by the HRRR across Pima county Monday morning.
Snow levels will still be on the high side, but fall as the low
shifts overhead Monday afternoon. Around 8800 feet in the morning
to around 8000 feet at noon, then as low as 7000 feet in the late
afternoon. Precip amounts ranging from 1/4 to 3/4 of an inch in
valleys, and 1 to 1.5 inches in the mountains (isolated higher
amounts). Much of that precip will fall as rain in the mountains,
but they should manage 3 to 6 inches above 7500 feet with up to 8
inches at highest mountain peaks above 8500 feet. Much cooler
with max temperatures in the 50s for most of the area before a
weakening front pushes in from the west between 11 AM and 3 PM.
Clearing from the west Monday evening with colder temperatures
Tuesday morning. 20s to lower 30s for most of the colder valleys
south and east of Tucson. Tucson Metro generally in the mid to
upper 30s, but isolated outlying and foothills locations could
briefly touch freezing Tuesday morning.
A dry northwesterly to westerly flow behind the system for the
rest of the week. Temperatures will recover to near seasonal
averages by the end of the week, with a few more degrees of
warming next weekend. Of particular interest, both the ECMWF
Weeklies and GEFS ensembles suggest lower height anomalies
through the region the last two weeks of December, with some
flavor of winter storm activity possible around Christmas.
Something to keep an eye on.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Public...Cerniglia/Meyer
Aviation...Rasmussen
Fire Weather....Rasmussen
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