Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/21/18
Area Forecast Discussion
National Weather Service Albany NY
938 PM EST Tue Nov 20 2018
.SYNOPSIS...
An Arctic frontal boundary will move through the area on
Wednesday, with some snow showers, squalls and gusty winds.
Behind the front, bitter cold temperatures will move in for
Thanksgiving and Friday. Temperatures will slowly moderate over
the weekend with the potential for light rain and a wintry mix.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 930 PM EST...Clouds broke up this evening across the
Hudson River Valley with the higher terrain and downwind of Lake
Ontario remaining mostly cloudy. 00Z soundings show combination
of steep low level lapse rates and high moisture content from
near H750 and lower over most of upstate NY. Inversion level
heights upstream per KBUF were near H800 with `conditional`
instability indices per BUFKIT. So this will result in light
yet continuous lake effect snows into the Dacks as mean flow
remains from the west overnight with uniform flow within the
layer. Still a window of opportunity for a couple lake snow
showers to drift down the Mohawk and into the Capital District
as we will retain the slight chance PoPs. Otherwise, did
increase cloud coverage per the RAP and new glance of the NAM
and satellite trends the past couple of hours. So we did
increase cloud coverage overnight into Wednesday morning.
Temperatures look on track so little enhancements needed with
this update.
Prev Disc..
Widespread cloudiness over the region but some down slope flow
is helping break up the clouds in some of the Hudson Valley.
Quite a bit of cloud cover upstream in western NY and into the
Great Lakes but there is a zone of better clearing north of the
U.S./Canadian border. Based on the flow off the Great Lakes,
siding with more clouds than clearing tonight but there will be
some intermittent breaks in some areas.
Light winds and more clouds than breaks suggests temperatures
should not drop quite to levels as cold as the guidance suggests
but just going slightly above guidance with the uncertainties
on the amount of breaks in the clouds later tonight. Some
scattered snow shower activity is still possible into the
western Mohawk Valley and southern Adirondacks tonight but just
scattered. Lows tonight in the 20s but some teens northern
areas.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
Strong northern stream upper energy approaches from Canada and
there is a good consensus that the best low level convergence
along the boundary layer thermal gradient and moisture gradient
tracks more through northern NY and northern New England. This
suggests the most solid and organized snow squall activity
would be in those areas. There is a good consensus in sources of
guidance that even if terrain breaks up any solid line of snow
squalls in NY, the Berkshires and NW CT, the extreme low level
instability and convergence would support scattered to broken
snow squalls along the leading edge of the deeper cold
advection.
So, temperatures will rise into the mid 30s to lower 40s ahead
of the front in eastern and southern NY but only 20s to lower
30s west and north. Temperatures will drop sharply when the snow
showers/squalls begin and then after the passage, temperatures
drop more and winds shift to a very gusty northwest. There
will be some dustings to under an inch in the snow
showers/squalls but visibilities will likely be reduced below
1/2 mile in the squalls, maybe near zero briefly.
Winds shift to northwest and north Wednesday night and Thursday,
which suggests any lake effect snow bands will transition
rapidly to multi bands aimed at areas near and west of the
western Mohawk Valley, Schoharie Valley and eastern Catskills.
Lows Wednesday night in the single numbers to lower teens but
near or just below zero in the southern Adirondacks. Wind chills
will lower to around 15 below in the southern Adirondacks as
well.
Gusty north to northwest winds and a sunny sky are expected
Thanksgiving but highs only in the teens to lower 20s and around
or just above 10 in northern areas. Winds ease Thursday night as
high pressure centers itself over our region. Lows in the low
single numbers in many areas and below zero northern areas.
Low level and upper ridging slowly shifts east of our region
Friday but such a cold start to the day, light winds and slowly
rising boundary layer temperatures will limit the warming
Friday. So, highs Friday in the 20s, with some upper 30s
southern areas and around 20 to lower 20s northern areas.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
A chaotic flow pattern is in store for the long term forecast period
with multiple chances for mixed precipitation.
Friday night through Sunday morning...High pressure will remain over
the region through Saturday morning keeping conditions dry. Clear
and calm conditions will persist Friday night into Saturday morning
allowing for good radiational cooling and lows in the teens. Clouds
will increase from west to east Saturday morning into the afternoon
as an upper trough extending from the northern plains into the
Carolinas approaches from the west. Multiple lows will materialize
ahead of the dynamic forcing resulting in messy/low confidence QPF
and thermal profile forecasts. A long fetch of Atlantic moisture
suggested by strong integrated vapor transport could bring ample
moisture to the region, but confidence is very low for how much and
where at this time. For now, have went with a blend of the GFS/ECMWF
for the Saturday night into Sunday morning system. Strong boundary
layer WAA will likely result in a non-diurnal temperature trend
Saturday night and should keep most of the precipitation in the form
of rain, with the higher terrain possibly seeing mixed
precipitation. This is reflected in the current forecast. Highs
Saturday will generally be in the 30s with the Mid-Hudson Valley
creeping into the low 40s.
Sunday afternoon through Tuesday...Very brief mid-level ridging will
be in place for the second half of Sunday possibly keeping
conditions dry, but with another low rapidly on the heels of the
first one, have kept chance PoPs in the forecast. Deterministic
guidance suggests that a rapidly translating upper low will briefly
cut off over the region on Monday, with another deeper upper closed
low swinging in right behind it. The lagging forcing for ascent
could result in an inverted trough over the region, which could
enhance precipitation rates and totals. Given the large variance in
thermal profiles, p-type will be vary difficult to determine, but
guidance would suggest mostly rain at this time. The main point is
that there is potential for another strong storm system early next
week and there could be potential hydrologic issue. Confidence would
increase for hydro issues if p-types for both of the systems are
primarily rain and if QPF is on the high end of guidance. Temps
should moderate to near normal for this period.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Outside of IFR conditions at KGFL, VFR or borderline MVFR
conditions at the remainder of the TAF locations tonight. As
weak frontal zone passes through, conditions may improve briefly
before MVFR CIGS impact KALB-KPSF-KGFL with perhaps a snow
shower in spots. The main aviation impact is expected on
Wednesday.
Arctic boundary is forecast to approach and move across the
region from around Noon through mid-afternoon. Snow
showers/squalls are expected to accompany its passage which may
impact KALB-KPSF-KGFL. KPOU may be too far south hence no
mention in the TAF at this time. Westerly winds will increase
with occasional gusts from mid morning and especially in the
afternoon.
Outlook...
Wednesday Night: Moderate Operational Impact. Windy With Gusts
To 30.0 Slight Chance of SHSN.
Thanksgiving Day: Low Operational Impact. Breezy NO SIG WX.
Thursday Night: No Operational Impact. NO SIG WX. Friday: No
Operational Impact. NO SIG WX. Friday Night: No Operational
Impact. NO SIG WX. Saturday: Moderate Operational Impact. Chance
of RA...SN. Saturday Night: High Operational Impact. Likely RA.
Sunday: Moderate Operational Impact. Chance of RA.
&&
.FIRE WEATHER...
An Arctic frontal boundary will move through the area on
Wednesday, with some snow showers, squalls and gusty winds.
Behind the front, bitter cold temperatures will move in for
Thanksgiving and Friday. Temperatures will slowly moderate over
the weekend with the potential for light rain and a wintry mix.
&&
.HYDROLOGY...
River flows will continue to lower into next week with colder
than normal temperatures continuing, and mainly light
precipitation events. No widespread hydro problems are
anticipated.
Scattered snow showers and squalls are expected along a cold
front Wednesday. Colder than normal temperatures persist into
the Thanksgiving holiday with flows continuing to recede.
For details on specific area rivers and lakes, including observed
and forecast river stages and lake elevations, please visit the
Advanced Hydrologic Prediction Service /AHPS/ graphs on our
website.
&&
.CLIMATE...
The record low max temperature for Albany for Thanksgiving Day is 19
degrees, set on Thanksgiving Day (November 28th) 1901. The record
low minimum for Thanksgiving for Albany is 5 degrees (November 23rd)
1972.
Albany`s record low max for November 22nd is 25 degrees set in 1880.
The low daily mean temperature is 18.5 degrees also set in 1880. The
record min temperature for November 22nd is 9 degrees set in 1969.
Daily records for Albany are from 1874 to 2017.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...NAS
NEAR TERM...BGM/NAS
SHORT TERM...NAS
LONG TERM...Cebulko
AVIATION...Frugis/BGM
FIRE WEATHER...NAS
HYDROLOGY...NAS
CLIMATE...
Area Forecast Discussion
National Weather Service State College PA
719 PM EST Tue Nov 20 2018
.SYNOPSIS...
An arctic cold front will move through the area Wednesday
ushering in fair weather, but also record-challenging cold for
Thanksgiving Day. Temperatures will moderate over the holiday
weekend with a new storm system likely to move into the region
for Saturday into Sunday.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Earlier snow showers have pretty much diminished to just a few
leftover flurries. Main adjustment in the near term was to
increase the cloudcover to fit current trends.
Winds that have picked up to 10-15 mph will tend to diminish
overnight before starting to pick up again toward sunrise. Lows
will average in the 20s.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
True arctic front arrives on Wednesday, with potential to
generate a heavier snow band as it sags southward. Main question
looks to be whether it will have enough moisture to work with.
Though marginal, enough other pieces in place to keep mention of
potential for this band based on HRRR forecasts and hints of
this feature in other models along with being the busiest travel
day of the year. If this band develops, it will impact the
northern mountains late morning/midday and slip toward I-80 in
the afternoon before washing out over the central mountains.
Cold air push will be accompanied by wind gusts that could get
around 30-40MPH on the ridges and 20-30MPH in the valleys.
850H temps only -8C to -12C likely holding max temps close to
30 in the NW and l40s in the SErn valleys.
Snow showers recede to the favored NW mountain areas Wed night
before tapering off as large high pressure builds in, bringing
lows Wed night 15-20F below normal as lows plummet to the single
digits north of I-80 and the teens elsewhere with a wind
knocking about 10-20F off of those numbers for the wind chill.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Arctic airmass will deliver one of the coldest Thanksgivings on
record in central PA. The record-challenging cold will feature high
and low temperature departures on the order of 15 to 30 degrees
below average. Single digit wind chills above and below zero
are forecast across much of the area from Thursday morning
through Thursday night into [Black] Friday morning. Although the
weather will be very cold, the air will also be very dry, which
means there won`t be any snowfall to worry about Thursday and
Friday.
Expect precipitation to return to the area on Saturday. The
retreating cold airmass sets up the potential for precipitation
to start as snow or a wintry mix before transitioning to rain.
Any wintry precip would be a high impact given the holiday
weekend and increased travel. This system should pull out
Saturday night with only a brief respite until the next system
arrives by next Monday. Colder air wrapping in behind this
system should eventually lead to snow showers downwind of lake
Erie with accumulation possible in the favored snowbelts and
upslope locations.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
MVFR to VFR conditions will continue overnight as precipitation
and winds decrease.
Main push of colder air will be on Wednesday. Models hinting at
potential for a stronger snow band dropping southward across the
mountains, impacting the northern mountains late morning/midday
and slipping toward I-80 in the afternoon before washing out
over the central mountains. Placed a general MVFR reduction in
visibility in snow timed with the arctic front Wed. afternoon.
The cold air push will be accompanied by wind gusts that could
reach 25-35kts on the ridges and 15-25kts in the valleys.
Widespread VFR conditions develop for Thu/Fri with high
pressure in control.
.Outlook...
Thu-Fri...No sig wx expected.
Sat...Wintry mix poss early, then restrictions in mainly rain.
Sun...Restrictions likely in rain showers.
&&
.CLIMATE...
Record-challenging cold is forecast for Thanksgiving Day. Both
record low-maximum (daytime) and record low minimum (nighttime)
temperatures are in jeopardy. *State College COOP records for
STCP1 taken between 7am-7am and coordinated with PSU Meteo
Dept.
Record low-min (11/22)
-------------------------
Williamsport: 13 in 2014
Harrisburg: 16 in 1964
Altoona: 13 in 1964
State College: 10 in 1984*
Bradford: 6 in 2008
Record low-max (11/22)
-------------------------
Williamsport: 30 in 2000
Harrisburg: 31 in 1989
Altoona: 27 in 2008
State College: 25 in 1956
Bradford: 20 in 2008
Record low-min (11/23)
-------------------------
Williamsport: 14 in 1964
Harrisburg: 14 in 1964
Altoona: 12 in 2000
State College: 12 in 1984
Bradford: -1 in 1971
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...La Corte/RXR
NEAR TERM...La Corte
SHORT TERM...Dangelo/RXR
LONG TERM...Steinbugl
AVIATION...RXR/Tyburski
CLIMATE...
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
312 PM MST Tue Nov 20 2018
.SYNOPSIS...
A weakening upper level disturbance will bring increasing clouds
to the area this evening, with showers developing overnight over
parts of El Paso, Hudspeth, and Otero counties. A stray
thunderstorm will also be possible. Snow levels will drop to
around 7000 feet, but the bulk of the moisture will remain south
of the higher terrain, thus no more than a dusting of snow is
expected there. The best chance of rain will be east of El Paso
and over Hudspeth County. Drier weather will prevail on Wednesday,
with cloudy but mild conditions expected for Thanksgiving Day.
Westerly winds may become breezy by late Thursday afternoon. A
more significant upper level disturbance will pass to our north on
Saturday, but it will send a cold front into the area Saturday
night, bringing cooler temperatures to start the week ahead.
&&
.DISCUSSION...
High and mid-level clouds are increasing over the area in
response to upper diffluence developing out ahead of an upper
level disturbance currently over southern Arizona. This system was
a closed low off California yesterday, but is expected to continue
to weaken as it moves across southern New Mexico tonight into
Wednesday morning.
While there will be a brief period overnight with favorable
dynamics for lift, as well as some moderate elevated
instability, moisture is generally lacking across the area, with
RAP soundings indicating PW values around 0.40 to 0.45" in Far
West Texas. Blended PW product shows similar values, but does
indicate slightly better moisture trying to work up the Rio Grande
valley into Hudspeth County. Surface dewpoints are in the 30s in
El Paso, Hudspeth, and southern Otero Counties, but sharply drop
off into the teens as you head north and west. As a result, expect
our PoP grids are in pretty good shape, keeping the best chance
for precip south and east of ELP, with slight chances extending
into the Sacramento Mountains and parts of southern Dona Ana
County. I did boost the max PoPs over Hudspeth/Southern Otero into
the 40s, and switched to coverage descriptors (`scattered` vs
`chance`) to suggest increased confidence in a spotty coverage/low
qpf scenario. A few rumbles of thunder will be possible given weak
to moderate (seasonally-speaking) instability aloft, and this is
also suggested in a few of the HREF members as well.
This system will pass east of the area tomorrow, with ridging
moving in from the west by late afternoon. A stronger shortwave
trough will pass well to our north on Thanksgiving Day, bringing
precipitation to northern New Mexico, and just a slight chance of
a shower over parts of our CWA. Mid and high level clouds will
be extensive, partially due to a rather strong 180-knot jet streak
over NM. While weak lee troughing will develop in the afternoon,
the surface pressure gradient and low-level winds look fairly
weak. It will become breezy in the afternoon over SW New Mexico,
but winds still look to top out in the 15-20 mph range, with
gusts to 25 mph.
Zonal flow will set in for Friday, with temperatures staying at or
slightly below normal. A more significant trough moving into the
Pacific Northwest Friday evening will drop to the SE, grazing
northern New Mexico on Saturday, and dropping a side door cold
front into our area Saturday night. Breezy to windy conditions
will be possible Saturday afternoon, but the timing of the trough
passage doesn`t look ideal for maximizing the wind potential.
Still, W to WNW winds with gusts in the 30-35 mph range are
possible late Saturday afternoon. A stray shower will be possible
in the Gila Region or Sacramento Mountains. Temperatures will drop
considerably behind the front on Sunday, with high temperatures
during the early part of next week looking to stay about 5 to 8
degrees below normal (lowland highs in the mid/upper-50s). Cooler
weather could be possible if this system can dig in a little
further to the south.
&&
.AVIATION...Valid 21/00Z-22/00Z...
VFR conditions will continue through the period. An upper trough
will be moving through overnight and bring FEW-SCT030-040 SCT-BKN080-
100 BKN150-200 with a few -SHRA to areas along and east of KALM-KELP
line. After 12Z skies will become SKC. Winds will generally be east
to southeast AOB 12KTS through period.
&&
.FIRE WEATHER...
The period will start out with upper trough moving across region
with mainly just some clouds, but isolated to scattered lowland
rain showers and mountain rain/snow over eastern third of area.
Upper ridge moves over area Wed/Thu which will keep temperatures
near to slightly above normal with relative humidities in the 30s
next couple days before winds shift to the west and increase to 15
to 30 mph and humidities fall into the mid teens to mid 20s for
Friday into the weekend. Vent rates will remain poor to fair to
start period before improving to very good with the increasing
westerly winds.
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 42 64 42 65 / 30 0 0 0
Sierra Blanca 39 57 40 68 / 30 0 0 0
Las Cruces 37 62 39 62 / 10 0 0 0
Alamogordo 34 62 37 63 / 10 0 0 0
Cloudcroft 29 45 30 47 / 10 10 0 10
Truth or Consequences 36 63 40 59 / 0 0 0 0
Silver City 33 60 36 55 / 0 0 0 10
Deming 33 63 35 63 / 0 0 0 0
Lordsburg 35 64 39 61 / 0 0 0 0
West El Paso Metro 44 63 44 64 / 20 0 0 0
Dell City 36 62 34 67 / 40 10 0 0
Fort Hancock 40 63 39 72 / 30 0 0 0
Loma Linda 37 61 37 63 / 40 0 0 0
Fabens 37 62 37 68 / 40 0 0 0
Santa Teresa 39 62 40 64 / 20 0 0 0
White Sands HQ 39 63 42 62 / 10 0 0 0
Jornada Range 33 62 39 61 / 0 0 0 0
Hatch 35 64 37 62 / 0 0 0 0
Columbus 36 64 38 64 / 0 0 0 0
Orogrande 37 63 39 64 / 20 0 0 0
Mayhill 31 55 33 57 / 10 10 0 0
Mescalero 29 54 31 54 / 10 0 0 10
Timberon 28 52 29 54 / 20 10 0 10
Winston 26 60 30 55 / 0 0 0 10
Hillsboro 31 62 34 59 / 0 0 0 0
Spaceport 35 63 37 59 / 0 0 0 0
Lake Roberts 22 61 25 54 / 0 0 0 10
Hurley 30 60 33 58 / 0 0 0 10
Cliff 28 66 30 60 / 0 0 0 10
Mule Creek 27 63 28 58 / 0 0 0 10
Faywood 34 60 36 58 / 0 0 0 10
Animas 35 65 38 63 / 0 0 0 0
Hachita 28 64 32 63 / 0 0 0 0
Antelope Wells 33 64 37 66 / 0 0 0 0
Cloverdale 37 64 40 60 / 0 0 0 0
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&
$$
25-Hardiman / 26-Grzywacz
Area Forecast Discussion
National Weather Service Green Bay WI
529 PM CST Tue Nov 20 2018
Updated aviation portion for 00Z TAF issuance
.SYNOPSIS...
Issued at 249 PM CST Tue Nov 20 2018
Quiet but chilly weather will continue through Thanksgiving Day,
with minimal weather-related problems expected for the beginning
of the holiday weekend.
The upper flow across North America is transitioning from having a
persistent, dominant mid-continent trough to a more progressive
zonal regime. The new regime will just be temporary as by early
next week the flow is expected to become highly split due to
developing blocking over northeast Canada. Upstream from the
block, a strong southern stream trough is likely to form over the
Great Lakes region.
Temperatures will remain below normal through tomorrow, moderate
on Thanksgiving, then spend at least a couple days above normal.
The eventual evolution of another trough over the Great Lakes
region will probably result in below normal temperatures again by
early next week. The current pattern is unfavorable for
significant precipitation, but will become more favorable as the
Great Lakes trough takes shape. The best estimate is for near normal
precipitation amounts for the period.
&&
.SHORT TERM...Tonight and Wednesday
Issued at 249 PM CST Tue Nov 20 2018
The latest RAP analysis and satellite/radar imagery show a weak
low pressure system moving over far northern MN early this
afternoon. Relatively narrow but still rather intense area of
mid-level warm advection is occurring ahead of the low, and
producing an area of light to moderate snow across north-central
WI. Up to an inch of snow remains possible in this area by the end
of the afternoon. Though it should be weakening, some light snow
remains possible to push into the Fox Valley around the evening
commute time. No solid indications thus far of freezing drizzle on
the back edge of the precipitation, but progged soundings
continue to indicate potential for a few hours over central an
and north-central WI late this afternoon. Wintry precip and cloud
trends are the main forecast concerns.
Tonight...The low pressure system will quickly moving across Lake
Superior and far northern Lake Huron, while dragging a cold front
across the area. The chance for light snowfall will likely
continue across eastern WI through about mid-evening associated
with the system, but will have mostly departed north-central WI.
However, spotty freezing drizzle will remain possible along back
edge of the precip for a couple hours once the snow has pulled
out. Do not think will see much in the way of impacts from any
freezing drizzle, and additional snow accumulations should only
amount to a tenth or two, possibly up to a half inch over Vilas
county. Though a period of partial clearing is possible right
behind the front, winds will turn to the northwest then north and
should continue to push in cloud cover. Left a chance of light
snow and flurries across far northern WI through the night, as it
does not take much to produce light snow this time of the year.
Due to the clouds, temps will not fall off much tonight, and will
go with lows ranging from the lower teens in the north to the
lower 20s over the southern Fox Valley.
Wednesday...Cold advection will continue as Arctic high pressure
builds in from the northwest. After some morning low clouds to
start the day, think these clouds and any snow showers/flurries will
retreat through the morning closer to Lake Superior. However,
guidance still points towards plenty of mid and high clouds
remaining overhead, so still thinking partly to mostly cloudy
conditions through the day. Chilly highs ranging from the middle
teens in the north to the middle 20s over the south.
.LONG TERM...Wednesday Night Through Tuesday
Issued at 249 PM CST Tue Nov 20 2018
Some lake-effect off Lake Michigan is possible Wednesday night
into Thursday morning in the easterly flow around the southwest
flank of an anticyclone passing north of the area. A strong
inversion around 850 mb should prevent anything more than flurries
or light snow showers.
The models were beginning to give some indication that some light
precipitation could develop over northeast Wisconsin Thanksgiving
day. A lack of deep saturation suggests any precipitation could be
FZDZ, which is concerning. But the departing air mass will still
be quite cold, so it is possible that low-levels will remain cold
enough to introduce ice crystals. It`s also possible the moisture
won`t be deep enough to produce any precipitation at all. So,
opted to keep just flurries in the northeast for the afternoon,
with a slight chance of FZDZ in the far northeast into the
evening. Later shifts can adjust as necessary.
The details of the complex system expected to affect the area
during the weekend are coming into a little better focus--at least
concerning the initial round of precipitation. Temperatures
should be warm enough for mainly rain to overspread the area
Friday afternoon and evening. The precipitation should stay liquid
in the east as southeast flow continues during the night. The
north and west could change to a rain/snow mix or possibly all
snow over the far northwest. But low-level temperatures probably
won`t be cold enough for much accumulation.
After a lull in the precipitation Saturday night into early
Sunday, the second round of precipitation should arrive as a
cyclone develops over the mid-Mississippi Valley and tracks
toward the lower Great Lakes region. Although rain or a mix of
rain and snow is possible over east-central Wisconsin early in
the event, north winds should eventually draw in colder air and
change the precipitation to all snow. Amounts will depend on how
quickly that occurs and how much precipitation remains on the
western flank of the cyclone. Will mention the overall situation
in the HWO, but also note that it will take a little while for the
details to get worked out given the complex nature of the system.
Overall, no significant changes were necessary to the standard
forecast initialization grids.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 529 PM CST Tue Nov 20 2018
A clipper system will bring MVFR cigs across the TAF sites and
turn winds to the northwest then north. Some flurries or patchy
freezing drizzle are possible this evening before precipitation
ends. A gradual improvement to VFR is then expected Wednesday
morning and into the afternoon hours as high pressure builds in
across the western Great Lakes, bringing drier air into the lower
levels.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS.......Skowronski
SHORT TERM.....MPC
LONG TERM......Skowronski
AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service Marquette MI
647 PM EST Tue Nov 20 2018
.SHORT TERM...(This evening through Wednesday)
Issued at 326 PM EST TUE NOV 20 2018
Water vapor imagery and RAP analysis show a strong ridge over
western N America with axis n thru BC/Alberta. Downstream, a deep
trof is over eastern N America with a shortwave diving se across
Manitoba into northern Ontario. At the sfc, the associated ill-
defined low pres is just nw of Lake Superior. Ahead of the
shortwave, push of waa/isentropic/deep layer forcing is supporting
light to at times mdt snow spreading over Upper MI early this aftn.
Shortwave currently tracking into northern Ontario will brush ne
Lake Superior tonight and reach New England late Wed. Sfc low, not
well-defined, will quickly track across Lake Superior this evening
with associated arctic cold front sweeping across the area. None of
the models show an especially sharp wind shift with the arctic front
as would normally be expected under antecedent strong overlake
instability present (850mb temps around -15C). Difficult to go
against multi-model agreement with that idea, but do think wind
shift and thus convergence will be sharper as front drops across the
wider expanse of eastern Lake Superior where sensible/latent heating
will be greater. Thus, other than the -sn currently spreading across
the area and ending over the next few hrs, still expect a burst of
briefly mdt/hvy shsn along the arctic front as it moves off Lake
Superior into Upper MI this evening, but the heaviest burst of snow
will occur e of Marquette when the front moves onshore in that area
late evening...maybe a quick inch. After the brief mdt/hvy shsn
along the front, nw flow wind parallel LES bands will quickly
organize during the night. However, fast arrival of subsidence,
drying and lowering inversion to 5kft w half and 7kft e half will
keep snow amounts in check and under advy criteria tonight. DGZ will
descend squarely into the convective layer under CAA driving 850mb
temps down toward -20C by 12z Wed, and this will raise snow-to-water
ratios to fluff up accumulations, but still don`t expect amounts to
reach advy. Only potential exception will be over n central Upper MI
as dominant LES band tied to Lake Nipigon preconditioning will
develop and stream onshore btwn Marquette and Munising overnight
before shifting solely into Marquette County early Wed morning as
winds begin to veer with arctic high pres building over northern
Ontario. High res guidance is not in good agreement on
location/timing movement of this dominant band. However, since the
high res NAM window has been quite consistent over the last few runs
and was similar to the 12z HRRR 36hr run, will lean more on those 2
solutions for the overnight/Wed morning time frame. As a result, for
now, 12hr snow amounts are only in the 2-4 inch range in the
aforementioned area, just blo advy criteria. 24hr snowfall from 00z
Wed to 00z Thu should be locally as much as 4-6 inches over Alger
County into northern and eastern Marquette County and basically 2-4
across the rest of the Lake Superior snow belts. Will be blustery
close to Lake Superior tonight/Wed morning with winds gusting 25-
35mph, so there will be some blsn.
Incoming arctic air mass is very cold for this time of year as
APX/GRB sounding climatologies don`t show many sub -20C 850mb temps
thru the first few weeks of Nov. Models indicate midday 850mb temps
on Wed ranging from -17C w to -22C e across the fcst area. Expect
min temps tonight in the single digits interior w half to near 20F
east near Lake Superior. Highs Wed may only reach the lower teens
interior nw/n central high terrain to around 20F s central and e
along Lake Superior. Record low max temp of 15F here at NWS
Marquette could certainly fall.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 419 PM EST TUE NOV 20 2018
Wed night starts off with upper level trough over much of eastern
Canada into the Great Lakes but ridging will be building from the
central Plains to south central Canada. May be a little lingering
nw flow LES for snowbelts of ncntrl to eastern forecast area on
Wed evening. High pressure at the sfc slides across later Wed
night which may result in inland locations dropping to near zero.
Looks pretty quiet on Thanksgiving though southeast winds from
the high and it remains cold enough aloft (850mb temps as low as
-14c) to support light lake effect snow. Snow accums should be on
the light side, but may see up to an inch Escanaba to Manistique.
Limited large scale forcing and deeper moisture are both negative
factors in seeing lake enhanced snow in this setup.
Warm air advection ramps up on Thu night as return flow develops
btwn departing high to the east coast and a low pressure trough over
the northern Plains. Soundings show shallow moisture so seems that
if there is precip would be drizzle or freezing drizzle. Right now
this looks like a low risk, but with a lot of people out on the
roads for Thanksgiving and Black Friday shopping will not take much
freezing drizzle to cause issues. Just not sure if there will be any
precip at all so a very low risk at this point.
Friday will be pretty quiet for most of the day. Though skies will
be mostly cloudy, warm air advection will allow temps to reach the
upper 30s to around 40F. Shortwave trough and sfc trough moving in
from the northern Plains will bring widespread precip across Upper
Michigan Fri night into Sat. Forecast soundings indicate that ptype
will mainly be rain but one thing to watch with this rain is fact
that we could see some non-traditional freezing rain as the rain
falls and possibly freezes on snow free and untreated roads. This is
due to the long cold stretch we have been in for most of this month.
Not sure if there will be enough warming on Friday ahead of the rain
to prohibit this. Will be something to keep an eye on as we get
closer. But, probably will not have great handle on this until
Fri aftn/Fri evening when current road sfc temps will be available.
Rest of extended keys in on strong shortwave/sfc low lifting out of
the central Plains Sun into Mon. Earlier GFS runs (not the 12z GFS
run) indicated strong sfc low close enough to result in significant
lake enhanced snow over northern Upper Michigan. Canadian-NH still
shows more of a farther north system with at least widespread light
snow over much of Upper Michigan. ECMWF keeps focus for this system
more south of Upper Great Lakes and eventually to the east coast.
The ECMWF idea and the 12z GFS would result in mainly light LES for
n-nnw flow areas on Mon. Overall there is a lot of uncertainty how
the early next week period works out. At the least it looks like
after the brief warm up Fri-Sat it will turn cool again by early
next week with snow as the only ptype.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 623 PM EST TUE NOV 20 2018
MVFR conditions are prevailing at KSAW and KIWD at the start of
this TAF period, with IFR prevailing at KCMX. Low ceilings and
visbys are expected to continue to dominate through the TAF period
at all three terminals, with perhaps some marginal improvement
possible by Wednesday evening. The primary time frames of concern
for the terminals are during the overnight hours, early on for
both KIWD and KCMX for snow bands potentially reducing visbys, and
gusty winds at KCMX. KSAW`s primary time frame of concern will
come later tonight through tomorrow morning as winds shifting from
the W-SW to out of the N sets the stage for lake-enhanced snow
banding to setup. Aviation interests should remain vigilant of the
possibility of lower categories at KSAW as the details of how
impactful the snow banding tomorrow morning comes into better
view with subsequent issuances.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 326 PM EST TUE NOV 20 2018
Arctic cold front will sweep across Lake Superior this evening. W to
sw winds ahead of the front may gust to gale force 35kt. After the
front passes, it looks more likely now that nw to n winds will gust
frequently to 35kt gales tonight across the e half of Lake Superior.
A gale warning has thus been issued for tonight. With the stronger
winds and very cold air, freezing spray will develop and may become
heavy over the ne portion of the lake. As arctic high pres builds
across northern Ontario toward Lake Superior on Wed, winds will
steadily diminish, falling to under 15kt w and under 20kt e by late
aftn. Winds will generally be under 20kt Wed night then increase
rapidly Thu as the high pres departs and a low pres trof moves out
over the Plains. Expect southerly winds of 20-30kt Thu into Fri.
Over the e half of the lake, gale force gusts will probably occur at
times. Winds will then diminish to under 20kt on Sat as the low
pres trof arrives. As the trof departs, winds will begin to
increase on Sun, but probably not until late in the day. &&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Warning until 7 AM EST Wednesday for LSZ248>251-265>267.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...JLA
AVIATION...lg
MARINE...Rolfson
Area Forecast Discussion
National Weather Service New York NY
1008 PM EST Tue Nov 20 2018
.SYNOPSIS...
High pressure briefly builds from the southwest tonight before an
arctic cold front approaches on Wednesday. This cold front moves
through Wednesday evening with high pressure building in for
Thursday. High pressure moves off into the Atlantic Ocean
Friday night. A low pressure area approaches Saturday and moves
across Saturday night into early Sunday. Weak high pressure
follows that and then another low moves in for early next week.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
On the heels of a shortwave trough that passed through this
evening, there will be a quick shot of cold advection with
occasional wind gusts up to 20 mph. A few minor adjustments were
made to forecast based on latest observations.
Deepening low pressure near Nova Scotia tracks NE overnight as
high pressure builds to our south and west. Drier air advects
into the region under a breezy westerly flow.
Clearing skies and diminishing winds will allow temperatures to
fall into the 20s inland/Pine Barrens of LI and lower 30s
closer to the coast.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
The main story for Wednesday will be the approaching arctic cold
front and anomalous upper closed low/trough digging towards New
England.
The day should start out mostly clear and chilly, but clouds begin
to increase into the afternoon as the front approaches. There is
good agreement among the models for the cold front to move across
the area in the evening. High resolution models including the
NAMnest and extended HRRR hint at a broken band of snow showers
along the boundary as the front moves through. Think this is
reasonable as there will be some weak instability in the low levels
as the cold air begins to move into the area. Probabilities for snow
showers will be held down in the slight chance range for now. The
timeframe for these snow showers looks to be from around 21-23z
across the northwest interior moving eastward thereafter from 23-
03z. Wind gusts in the afternoon and evening look to be 20-30 mph,
but gusts could briefly end up higher along the frontal passage and
in any snow shower.
High temperatures will continue below normal in the low 40s inland
and the middle 40s closer to the coast.
Significant cold air advection commences Wednesday evening behind
the front and as the deep upper low shifts over northern New
England. Anonymously cold and unseasonable air will quickly
overspread the region Wednesday night into Thursday morning. 850 mb
temperatures go from -8 to -12C at 00z Thursday to -16 to -19C by
day break Thursday morning. These readings are near the minimum
observed for November 22 (-17C) based on sounding climatology from
SPC.
Surface temperatures will start out in the 30s in the evening and
drop considerably through the night with temperatures in the teens
inland and near 20 in the NYC metro and Long Island by day break.
Blustery NW winds will make it feel like the single digits early
Thursday morning.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Polar jet will be across the region Thursday through Friday with
more of a split jet structure across the region for the weekend.
Subtropical jet strengthens and approaches the region late in the
weekend. This moves into the region early next week.
At the surface, very cold airmass builds in for Thursday through
Friday as strong Canadian high pressure builds in. Strong subsidence
will keep dry conditions during this time period along with
temperatures well below normal. Highs forecast on Thursday stay in
the 20s with highs near 30 forecast on Friday. Breezy conditions
Thursday will decrease Thursday night into Friday with a decrease in
the pressure gradient.
A more unsettled weather pattern unfolds thereafter. Troughs move in
late Saturday into Sunday and early next week with accompanying
low pressure systems at the surface. The airmass will be
moderating Friday into the weekend so with a more southerly flow
Friday night into Saturday, this will moderate temperatures with
highs Saturday in the mid 40s to near 50. The timing of the system
with abundant clouds Saturday night and onshore flow is expected
to keep temperatures in the upper 30s to mid 40s. Lower 50s
forecast max temperatures Sunday will be followed by mid 30s to
low 40s min temperatures Sunday night as well as mid 40s to low
50s for max temperatures Monday. So, the two systems moving in for
the long term period look to be mostly stratiform rain.
Please see our social media platforms for a graphic displaying
the top 5 coldest high temperatures and top 5 coldest low
temperatures for the Thanksgiving holiday at Central Park.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
High pressure builds in from the west tonight. An arctic front
passes late Wed.
Mainly VFR through the TAF period. A brief period of MVFR or lower
possible 21z Wed thru 2z Thu in isold-sct shsn.
Diminishing NW winds tngt, then speeds increase again during
the day Wed, and particularly behind the arctic front late.
.OUTLOOK FOR 00Z THURSDAY THROUGH SUNDAY...
.Wednesday Night...VFR. Low chance MVFR or lower in shsn in the eve.
W-NW winds G20-30kt.
.Wednesday Night-Thursday...VFR. NW winds G25-30kt.
.Friday...VFR.
.Saturday...VFR early...followed by possible MVFR in the afternoon.
.Sunday...MVFR early...VFR in the afternoon.
&&
.MARINE...
Marginal SCA conditions on the ocean, eastern LI Sound and
eastern bays overnight. Ocean seas may build to near 5 ft
tonight. Winds may briefly weaken early Wednesday morning before
increasing on all waters late morning into the afternoon ahead
of the cold front. Ocean seas will build to 5 to 7 ft in the
afternoon and evening as well. Headlines remain in place tonight
but have adjusted the start time for the SCA on the NY Harbor,
western LI sound, and Great South Bay to 15z Wednesday.
The cold front crosses the waters Wednesday evening with the
potential for gales on the ocean, eastern LI sound and eastern LI
Bays. Confidence in gales occurring is not high enough to
convert the watch over to a warning at this time, but have
extended the SCA on the NY Harbor, western LI sound and Great
South Bay through Wednesday night. The gale watch has been
extended into Thursday as gales remain possible.
Gales will be probable across the eastern and ocean waters to start
the long term period Thursday with otherwise widespread across SCA
winds. Winds decrease Thursday night but still will be mainly SCA
levels. SCA winds return Saturday night for the ocean. Otherwise,
Friday through Sunday night, below SCA winds are forecast.
Ocean seas are forecast in the SCA range Thursday into Thursday
night as well as Saturday night through Sunday night. Otherwise,
seas are below SCA.
&&
.HYDROLOGY...
No significant hydrologic impact expected through the rest of
the week.
&&
.CLIMATE...
Record low temperatures for Thu Nov 22:
Central Park.....13 (1880)
LaGuardia........21 (1987)
Kennedy..........20 (1987)
Newark...........19 (1987)
Bridgeport.......18 (1987)
Islip............20 (1987)
Record low maximum temperatures for Thu Nov 22:
Central Park.....23 (1880)
LaGuardia........31 (1972)
Kennedy..........34 (2008)*
Newark...........33 (1949)
Bridgeport.......30 (1972)
Islip............31 (2008)
Record low temperatures for Fri Nov 23:
Central Park.....14 (1880)
LaGuardia........23 (1972)
Kennedy..........25 (2008)*
Newark...........21 (1932)
Bridgeport.......16 (1972)
Islip............13 (1989)
*also occurred in previous years
&&
.EQUIPMENT...
NYC Central Park winds are out of service until further notice.
Loss of data is due to a severed cable, parts are on order.
NYC NOAA Weather Radio Station KWO35 (162.55 MHz) will remain off
the air for an extended period of time.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 10 AM Wednesday to 6 AM EST Thursday
for ANZ335-338-345.
Gale Watch from Wednesday evening through Thursday afternoon
for ANZ330-340-350-353-355.
Small Craft Advisory until 6 PM EST Wednesday for ANZ330-340-
350-353-355.
&&
$$
SYNOPSIS...JM/DS
NEAR TERM...DS/DW
SHORT TERM...DS
LONG TERM...JM
AVIATION...JMC
MARINE...JM/DS/DW
HYDROLOGY...JM/DS
CLIMATE...//
EQUIPMENT...//