Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/30/18
Area Forecast Discussion
National Weather Service Gaylord MI
857 PM EST Mon Jan 29 2018
.UPDATE...
Issued at 857 PM EST Mon Jan 29 2018
Better lake effect snow bands, with a solid connection to the
fattest part of Lk Superior, have been gradually pushing east into
the Gd Trav Bay region. Radar returns have been intensifying,
though activity remains a bit on the disorganized side. Digging
shortwave will act to amplify activity with forcing and better
moisture over the next several hours, with drying/subsidence
likely leading to slowly diminishing intensity by late in the
overnight.
Rap/HRRR both advertising a shift in highest QPF tonight from
earlier expectations, to near/east of Gd Trav Bay instead of west.
This is in line with current surface obs, with TVC showing lower
vsbys than FKS/MBL this evening. This is also in line with what
one would expect with a nw/nnw fetch. HRRR QPF progs are pushing
0.25" in eastern Gd Trav Co by morning. 850mb temps are just
barely on the warm side of -20C. Though convective cloud depth is
a bit shallow, max omega in the 3-5k ft layer is well placed in
the DGZ. So the fluff factor should be high...better than 20-1 for
sure.
So snow amounts east/se of Gd Trav Bay have been seriously ramped
up. Thru Tue morning, a general 1-4" with a max of 4-6", centered
on an area surrounded by Elk Rapids-Kalkaska-Fife Lk-east end of
TC. Could well let this adjustment pass without an advisory, but
given it`s been weeks since we`ve seen anything resembling a
decent snow, have chosen to be more aggressive in approaching
headlines. Winter wx advis has thus been issued for Gd Trav/
Antrim/Kalkaska Cos.
&&
.NEAR TERM...(Tonight through Tuesday)
Issued at 328 PM EST Mon Jan 29 2018
High impact weather potential: Minimal. Light snow accumulation in
the Grand Traverse Bay region.
Pattern synopsis and forecast:
Upper troughing over the Great Lakes, with a weak shortwave sliding
SE into western Lake Superior, bringing a definite swath of low to
mid level moisture and patchy light synoptic snows. Low pressure was
lifting NE into western PA, with an inverted sfc trough axis
extending back through nrn Michigan. The increased mid level
moisture that was helping the lake effect and snows associated with
the inverted sfc trough, has been exiting the area and snowfall has
diminished some. Best snows now in northerly flow, along coastal
areas from Leelanau county south, where the longest fetch resides.
Otherwise just some scattered flurries around. Most all of nrn
Michigan remained in low level clouds due to moisture locked in
underneath an inversion.
The latest data has been doing poorly with handling the snow and it
appears this will be the case tonight as well. First off,
consistently through the day, data suggests a much slow arrival time
of drier air slipping down from Ontario through eastern Chip/Mack
and eventually through interior nrn lower. There is at least a
chance that this will not even occur, and the low level cloud/lake
effect steering flow will be increasingly more NW/NNW. This will be
a backing wind, as the aforementioned shortwave arrives this evening
bringing the light synoptic snows/increased mid level moisture. This
will most expectedly enhance the weak lake effect, before weakening
again through the overnight hours and into Tuesday morning with it`s
departure. Best snows still pointing toward the GTV Bay region, and
western sections of Chip/Mack counties of eastern upper. Ultimately
these snows will push more inland across NW lower as winds back more
westerly west of lake aggregate troughing. The troughing is expected
to shove west of SSM and much of Interstate 75 in eastern upper, due
to downsloping NE winds coming out of Ontario. This would shove
snows west of most of chip/Mack through the overnight and Tuesday
morning. Maybe an inch/inch and a half in NW Chippewa. The air mass
drier through the remainder of Tuesday, and winds go light with high
pressure settling overhead. Any lake effect will diminish through
the day or go offshore.
Lows tonight in the single digits most areas tonight, with highs
Tuesday in the teens north and the lower 20s south.
&&
.SHORT TERM...(Tuesday night through Thursday)
Issued at 328 PM EST Mon Jan 29 2018
...Widespread snow Tuesday night - Wednesday...
High Impact Weather Potential: Widespread snow arrives Tuesday night
and continues into Wednesday with the greatest accumulation expected
across eastern upper Michigan. Increasingly gusty winds may create a
further reduction to visibilities in some areas.
Pattern Forecast: Weak mid-level ridge axis will briefly become
centered overhead Tuesday evening with low level return flow ongoing
ahead of an area of low pressure progressing from southern
Saskatchewan into Manitoba overnight. Warm front crosses the area
from southwest to northeast Tuesday night with snow becoming likely
across the entire forecast area by Wednesday morning. The system`s
cold front blasts through northern Michigan Wednesday night into
early Thursday with a return to below normal temperatures and lake
effect snow chances.
Primary Forecast Concerns/Challenges: Snow arrival timing Tuesday
night and accumulations through Wednesday. Increasing lake effect
potential Thursday.
Focus will revolve around the aforementioned area of low pressure
expected to cross north of the forecast area Tuesday night into
Wednesday with widespread snow expected across the forecast area.
Fairly decent guidance agreement at this juncture with respect to
snow arrival timing...initially becoming likely across eastern upper
and far northwest lower by midnight Tuesday night before gradually
pressing eastward with at least light snow falling across the
majority of the forecast area by the Wednesday morning commute.
Marginal lake enhancement in southwest flow off Lake Michigan and
respectable forcing along the front will provide a focus for bursts
of moderate snow at times into Wednesday morning, especially across
the U.P. Combined with a tightening pressure gradient resulting in
increasingly gusty winds, blowing snow could bring further reduction
to visibility (and hazardous travel) in some locations. Steady snow
diminishes from west to east late Wednesday morning into the early
afternoon hours as moisture quickly strips off to the east. All in
all, between Tuesday night and Wednesday, 3-6 inches of accumulation
are expected across eastern upper with 1-3 inches across northern
lower (locally higher across the Tip of the Mitt).
A fairly impressive cold front is expected to quickly cross the area
from northwest to southeast Wednesday night with H8 temps progged to
fall from roughly -7 C at 00z Thursday to -18 C by 12z Thursday with
CAA continuing through the remainder of the day and H8 temps falling
to low 20s below zero by the afternoon hours. As a result,
increasing over-lake instability and pockets of deeper moisture
pinwheeling around the backside of the departing low pressure will
provide a focus for lake induced snow showers to become the rule,
most persistent across the typical west-northwest flow locales of
eastern upper and northwest lower.
Wednesday`s temperatures are expected to prove to be a few degrees
above normal under ongoing warm air advection, despite widespread
snowfall. Highs ranging from the low 30s across eastern upper to the
mid 30s elsewhere. Sharp drop in temps expected Wednesday night with
lows falling into the teens for most and early day highs on Thursday
varying from the teens across eastern upper and northwest lower to
the low mid 20s near Saginaw Bay...likely falling during the
afternoon.
.LONG TERM...(Thursday night through Monday)
Issued at 328 PM EST Mon Jan 29 2018
High impact weather potential: Moderate; bitter cold temperatures
with below zero wind chills and lake snows through the period.
Mid level temperatures will plummet across the region Thursday night
and Friday, as Arctic air floods the Great Lakes. 850mb temperatures
in a deepening 500mb trough, will drop to between -24c and -26c
Friday and through the weekend. This will generate well below normal
high temperatures (in the teens) through Monday. Snow will be common
across northern Michigan through the weekend. Lake Michigan snow
belt areas will see the most persistent snowfall and highest
snowfall potential, as winds slowly vary between SW-NW into Monday.
A frontal boundary dropping south across the region Friday, will
enhance snowfall across all of northern Michigan Friday night
through Saturday night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 636 PM EST Mon Jan 29 2018
Cigs have been lifting somewhat during the afternoon/early
evening, with most places now VFR (APN is an exception). Expect
cigs to head lower again for tonight, and again a mix of VFR/MVFR
cigs are expected. Light lake effect snow showers will persist,
especially in the Gd Trav Bay region. Would not be surprised to
see brief IFR vsbys at TVC tonight.
Northerly winds will become light tonight, and will back toward
the sw Tuesday.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY until 11 AM EST Tuesday for MIZ021-026-
027.
&&
$$
UPDATE...JZ
NEAR TERM...SMD
SHORT TERM...MG
LONG TERM...SR
AVIATION...JZ
Area Forecast Discussion
National Weather Service Columbia SC
1034 PM EST Mon Jan 29 2018
.SYNOPSIS...
A dry pressure ridge will approach from the west through
Tuesday and extend through the forecast area Tuesday night and
Wednesday. The ridge will be off the Southeast Coast Thursday.
A cold front will move through the forecast area late Thursday
night and bring a chance of showers. It will be cool and dry
Saturday but another frontal system will move into the area
Sunday.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Some light shower activity still being indicated across the
central Appalachians on radar late this evening. Latest hrrr
guidance trying to indicate some of those showers will push
eastward into the NC piedmont late tonight as a weak shortwave
moves through. This may bring a brief isolated shower across
the extreme northern portions of the cwa overnight, with drier
air taking control towards morning. Overnight lows remain on
track to fall into the 30s.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Dry ridging moving into the forecast area from the west Tuesday
will be over the area Tuesday night and Wednesday. Expect mostly
clear skies. It will be breezy ahead of the ridge Tuesday.
Model time-height displays and expected mixing support gusts
around 20 mph. Wind will become light Tuesday evening as the
ridge moves into the area. Strong net radiational cooling will
occur and expect the coldest night of the week Tuesday night.
The guidance consensus supports lows mainly in the middle 20s.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
A moisture increase and temperature moderation should begin
Thursday with the ridge axis off the coast. The GFS and ECMWF
show the next cold front moving through the forecast area late
Thursday night. The models have trended faster with the frontal
timing and the latest guidance shows the greatest rain chance
late Thursday night. We maintained a small pop for now on Friday
because of uncertainty with the frontal timing. Dry high
pressure behind the front should dominate Saturday, but moisture
may begin to increase again in an onshore flow ahead of the
next frontal system forecast to arrive Sunday. This system may
linger Monday. The GFS and ECMWF MOS support pops around 40
percent.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
VFR conditions expected through the period. Skies to become
mostly clear overnight. Expecting dry conditions the remainder
of forecast period with drier low level air filtering in. Will
indicate LLWS due to indications of a low level jet. Combination
of drier air, and wind staying up some, will preclude any
fog/stratus concerns late tonight/Tuesday morning. Breezy
conditions possible Tuesday.
EXTENDED AVIATION OUTLOOK...Restrictions possible Wednesday
night and again Thursday night into Friday as another cold front
crosses the area.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service State College PA
1018 PM EST Mon Jan 29 2018
.SYNOPSIS...
An upper air disturbance will bring a widespread light snowfall
to the area tonight and Tuesday morning. A pair of cold fronts
will affect the area Wednesday night and again Friday.
&&
.NEAR TERM /THROUGH TUESDAY/...
Radar shows the first snow moving slowly through the Laurels
well out ahead of the main area of precipitation that is now
moving through western PA. Satellite shows cloud tops cooling
ahead of the digging-yet moisture starved shortwave moving
through the lower lakes and OH Valley.
Respectable upper height falls will support an area of
steepening mid level lapse rates sliding east overnight adding
a possible convective element to the expected precipitation.
Models are generating mid level lapse rates in the range of
7-9C/km with the GFS showing Total-Totals nearing 60!
HRRR times the main area of snow into the region after 03Z/10PM
and shows activity winding down by mid to late morning.
Widespread QPF of .10-.20" over central and eastern areas, and
maybe closer to .25-.30" over western and northern higher
elevations support the general 2-5 inch snowfall we have in the
forecast.
Main change with the near term was to extend the advisory to
Cambria and Clearfield to better match our snowfall forecast.
&&
.SHORT TERM /TUESDAY NIGHT/...
High pressure will build in with colder cold and dry conditions
for Tuesday night.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
The medium to long range will feature a continued train of
northern stream shortwaves (clippers) and generally weak/
relatively moisture- starved sfc reflections moving southeast
across the Great Lakes and Mid Atlantic Region with a period of
36-42 hours.
The primary sfc-850 mb lows again will be rather ill-defined
and will also move by just to the north of the state, which
means little threat for more than a few to several inches of
snow from any one event.
Each of these features will be preceded by a brief warmup to
near or slightly above normal temps, and followed by an 18-24
hour period of much below normal temps, gusty northwest winds of
30-35 mph, and bitterly cold wind chills near to below zero F
across at least the Central and Northern Mtns.
The precip Thur into Thu night could be a bit more prolonged
over the CWA (and mixed across the SE zones) as the approaching
cold front becomes parallel with the SW flow aloft for a
several-10 hour period. Still the precip "mixture" would be in
the form of rain/wet snow in contrast to any freezing precip as
the blyr will be warm but temps several KFT AGL still below
freezing. The precip type will change over to snow in all areas
by the time Phil comes out of his hole early Friday to check
out the conditions, and give us his prognostication for the
second half of the winter.
The coldest period of the upcoming 7 days will be Friday. High
then will only make it to the mid-upper teens across the
northern and western high terrain, and mid 20s to near 30F in
the Central and SE valleys.
The second feature will fall within the Sat night/Sunday period.
Again, expect a 1-2 inches of snow in most places, with locally
3-4 possible, mainly across the Laurels and NW Mtns.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Low pressure will track across Pennsylvania tonight and early
Tuesday, accompanied by a period of snow and followed by gusty
northwest winds on Tuesday. 00Z radar loop showing a few snow
showers entering the Allegheny Plateau, which could potentially
cause tempo vis reductions at KBFD/KJST between 00Z-03Z.
However, model data indicate the bulk of the snow, accompanied
by IFR/LIFR vsbys, will occur between 05Z-11Z over the western
mountains (KBFD/KJST), between 07Z-09Z at KAOO, between 09Z-11Z
in the vicinity of KUNV and between 11Z-15Z at the eastern
airfields from KIPT south through KMDT/KLNS.
Expect conditions to improve from west to east during the late
morning, as low pressure exits the area. However, gusty
northwest winds will develop behind this system. Bufkit
soundings support wind gusts of 25-35kts by afternoon, with the
highest winds over the south central part of the state.
Outlook...
Wed...No sig wx expected.
Thu...Light snow possible, mainly western Pa.
Fri...Early AM light snow possible.
Sat...PM light snow possible northwest Pa.
&&
.HYDROLOGY...
Hydro concerns continue on Susquehanna River below Marietta
around Turkey Hill where ice jamming could still cause highly-
localized problems. Thus the flood watch for Lancaster and
York counties remains in effect through this afternoon. Water
levels are generally falling on the river and hopefully the ice
jam threat will taper off.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 1 PM EST Tuesday for PAZ004>006-
010-011-017-024-033-037.
&&
$$
SYNOPSIS...La Corte
NEAR TERM...La Corte
SHORT TERM...La Corte
LONG TERM...Dangelo/Lambert
AVIATION...Fitzgerald
HYDROLOGY...
Area Forecast Discussion
National Weather Service Green Bay WI
546 PM CST Mon Jan 29 2018
Updated aviation portion for 00Z TAF issuance
.SHORT TERM...Tonight and Tuesday
Issued at 254 PM CST Mon Jan 29 2018
The latest RAP analysis and satellite/radar imagery show upper
troughing persisting over the western Great Lakes early this
afternoon. Northwest flow between high pressure over Minnesota and
low pressure over the east-coast is still contributing to broken
clouds across much of northern and eastern WI. An area of clearing
is moving across central WI, and should see this clearing move
into eastern WI later this afternoon. Partial clearing should
also move into north-central WI later as well, but with flow off
Lake Superior and another area of clouds over northeast
MN/northwest WI expected to arrive later, the clearing should be
relatively temporary. As the surface high moves across the area,
clouds trends and min temps are the main forecast concerns.
Tonight...A shortwave trough will move across northeast WI during
the evening. Therefore expect broken clouds and a few flurries
to likely linger over far northern WI early in the evening, then
should see clearing occur from southwest to northeast as high
pressure slides into the region. With the clearing skies and winds
diminishing, temps will likely tumble late tonight. Lows below
zero over the northwoods are likely, while temps in the Fox Valley
and lakeshore will remain around 5 to 10 degrees above zero.
Tuesday...High pressure will quickly shift to the central Great
Lakes. After a cold start, ample sunshine and a developing south
wind should help temps to warm up quickly. Clouds will then
increase from late morning through the afternoon ahead of the next
system passing across south-central Canada and the far northern
Plains. Models continue to indicate that fgen in the warm
advection zone will lead to a band of light snow moving across
northwest WI in the afternoon, and possibly reaching north-central
WI after 3 pm. Could see a couple tenths of accumulations by the
start of the evening over western Oneida and Vilas counties.
Highs ranging from around 20 in the north to the mid or upper 20s
in the south.
.LONG TERM...Tuesday Night Through Monday
Issued at 254 PM CST Mon Jan 29 2018
An upper trough and surface cold front will approach the area
Tuesday night and early Wednesday. Upper level support is very
good, but there is little moisture available. So only and inch or
two of snow is expected near the Michigan border and over Door
county with an inch or less elsewhere.
Much colder air and snow showers will arrive Wednesday night behind
the front with subzero wind chills across most areas by Thursday
morning. Cold advection will continue Thursday and Friday with
possible wind chill advisories needed Thursday night north and
west of the Fox Valley.
A surface wave moving along an approaching arctic cold front will
bring some light snow to the region Friday night and Saturday. It
will be followed by even colder air for Sunday and Monday. Wind
chill advisories and warnings will likely be needed. Temperatures
Sunday and Monday will be 15 to 20 degrees below normal.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 538 PM CST Mon Jan 29 2018
Low clouds have departed most of the forecast area, but mid-level
clouds will move through during the evening. There is a small
chance of fog over north central and central WI late tonight into
early Tuesday, but confidence is not high enough to include in the
TAFs at this time. The main aviation concerns will arrive in north
central WI late Tuesday afternoon. Light snow and LLWS will develop
at the RHI TAF site in advance of a clipper low pressure system
late in the day.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......RDM
AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Gray ME
941 PM EST Mon Jan 29 2018
.SYNOPSIS...
Low pressure developing off the Mid Atlantic coast early this
evening will move northeastward toward the Maritimes Tuesday.
As the system moves northeast, a little light snow may brush
the coastline tonight into Tuesday. High pressure will build in
Wednesday. A warm front will move in from the west on Wednesday
night with some light snow ahead of it. A cold front moves
through from the northwest Thursday evening with a return to
much colder temperatures behind it through the end of the week.
Another weak system may affect the region late in the weekend.
&&
.NEAR TERM /TONIGHT/...
945PM UPDATE...
With winds shifting to northerly and drier and drier air moving
in, it is becoming less likely that much if any snow will make
it to the coast tonight as this dry air will likely erode the
back edge of the precipitation area. Have updated the forecast
to reflect this dry air and make a few more minor adjustments to
precipitation chances.
630PM UPDATE...
Made some minor adjustments to temperature, dewpoint, and
precipitation chances during tonight. Some snow showing up on
radar over southern New England this evening, but models
indicating this may not make it up here. Will hang on to a
chance of snow along the coast, with the best chance near the
MidCoast.
ORIGINAL DISCUSSION...
High Impact Weather Potential: A period of light snow along the
coast is possible after midnight.
Pattern: Early afternoon water vapor reveals a ridge / trough setup
over North America...with the the trough member of this duo nearing
the Atlantic seaboard and spawning cyclogenesis off the east coast.
There is one plume of moisture along the coastal baroclinic zone
that has produced clouds over southeastern portions of our
area...particularly this morning with another upstream area
associated with the mid level trough axis and associated short wave.
The primary challenge through the near term forecast period revolves
around the developing coastal low pressure system and whether it can
push enough moisture/lift to the west to allow for any snow to reach
the coast.
Through this Evening: Varying levels of clouds out there as of this
writing...with upper level cloudiness having moved east with 3-5kft
clouds over much of central/northern NH and extreme western
ME...with eroding 2-3kft cloudiness over far southeast NH. Expect
some modest improvement in this lower cloudiness through early
evening...but this will be tempered by advancing mid clouds now seen
over southern New England moving north. Thus...partly to mostly
cloudy skies will continue with temperatures likely only falling a
couple of degrees through 8pm.
Tonight: Somewhat challenging forecast tonight as neutrally-
tilted trough shifts east overnight with surface low pressure
passing roughly 125 miles southeast of the benchmark overnight.
While this track in and of itself would suggest really no
threat to the area...the upstream H5 trough is rather
impressive...with this forcing interacting with moisture on the
western flank of the departing low and an associated deformation
field to produce a band of light snow that will likely impact
at least coastal portions of the CWA. While much of the 29.12Z
guidance trend has been a bit further south and east /most
notably the NAM/...this was not the case with the EC...which
actually has a better handle on the upstream trough. Recent HRRR
runs suggest a band of light snow west of the primary
precipitation shield...expanding into southern NH around
midnight and then to the north and east. Model soundings show a
rather deep near saturated layer in the dendritic growth zone
which is very efficient at producing snow with any lift.
Thus...will boost PoPs to likely along the immediate coast for a
time in the 06-12Z window...and expand chances further inland.
Overnight lows won/t be all that cold /esp in the south/ given
increasing cloud cover...but a strengthening northeasterly wind
will advect cooler air in overnight...with lows in the single
digits in the mountains...and in the teens and lower 20s to the
south. For immediate coastal communities...less than an inch by
daybreak...but some slick travel for the morning commute is
possible...and will mention this in the afternoon Hazardous
Weather Outlook.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
High Impact Weather Potential:
*Light snow along the coast lingers through mid morning.
*Low risk of minor coastal flooding from Portland south with the mid
morning high tide.
Pattern: Mid level trough axis moves overhead during the day
Tuesday and then east of the region Tuesday as an elongated axis of
high pressure builds in from the west. Primary forecast challenges
through the period include any coastal snow Tuesday morning and the
amount of clearing that we can accomplish during the day Tuesday.
Tuesday: Any ongoing light snow will gradually shift east during the
morning hours as low pressure departs to the east. Given the
placement of the DGZ...cannot rule out a fluffy 1-2" in a few
spots...with most locations likely not seeing much more than a
coating. For the afternoon...lots of mid level moisture will
remain...co-located with the mid level trough axis...and thus
do not expect much in the way of clearing during the day...with
the best chance for any sun over northern areas. Modest cold
advection will take T8s back to -10 to -15C during the day /not
significantly different than what is typical for this time of
year/ with this and significant cloud cover likely holding
temperatures in the teens in the far north and generally 20s
elsewhere with a few spots in southern NH making a run at 30.
Tuesday Night: With trough axis pulling to the east...a narrow
shortwave ridge axis will take its place...with a narrow ribbon of
surface high pressure associated with this feature dominating our
weather for the overnight period. The airmass will be seasonably dry
with PWATs dropping to around 0.1" towards daybreak Wednesday. While
there will likely be some remnant mid level cloud cover along the
western flank of the departing mid level trough axis through the
evening...expect an overall clearing trend which...with the dry
conditions and decoupling winds should allow for a rapid fall with
single digits above and below zero away from the coast...with lows
near 10F at the coast...right at the cold edge of the guidance
envelope.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
The long term period will mostly be dominated by zonal to
weakly amplified flow which will allow for mainly weak and fast-
moving low pressure systems to move across our region from time
to time. As a result, no major precipitation systems are
expected and this will coincide along with temperatures near
normal values.
The first weak system of interest moves on through Wednesday
night. This will take the form of WAA in association with a warm
front. Forcing for ascent should be quite weak, so we are only
expecting a relatively short bout of light snow - mainly across
the northern half of the CWA Wednesday night. This may deliver a
quick inch or so to these areas. The next in a series of fast-
moving short wave troughs approaches early Thursday. This one
will be associated with a SFC cold front that will sweep across
the area Thursday night. Snow showers along with some rain
showers will be possible along and in advance of this front,
but once again, the precipitation is expected to be light.
Quite the cold shot will move into northern New England in the
wake of the cold front Friday with much below normal
temperatures into Saturday. However, with progressive flow
across the country, this cold shot will be short lived. Several
deterministic models and ensemble members indicate that another
low pressure system will approach Saturday with some light
precipitation for Saturday night and Sunday, but again it will
be pretty weak. Therefore, only light amounts of snow and/or
rain will be possible.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Short Term...
Summary: Low pressure will move north and east well off the New
England tonight and early Tuesday with high pressure gradually
building into the region from the west late Tuesday and Tuesday
night.
Restrictions: A period of MVFR cigs is possible PSM-PWM-RKD-AUG
after midnight tonight through mid morning on Tuesday as light
snow nears the coast. There is a low threat for a period of
1-2SM visibilities during this period as well. It is possible
that this reaches back to MHT overnight...with VFR ongoing at
LEB/CON/HIE. Conditions return back to VFR by late morning
Tuesday /a bit later at RKD/ with VFR beyond this through
Tuesday night.
Winds: Northeast winds 5-10kts will become northerly tonight
and eventually northwesterly around 10g18kts for the day on
Tuesday before diminishing to less than 5kts Tuesday night.
LLWS: LLWS not expected through Tuesday night.
Long Term...Clouds and light snow move in Wednesday night with
conditions likely becoming MVFR or IFR - mainly across northern
and central portions of the forecast area. Should see some
improvement on Thursday with more showers/snow showers possible
Thursday night as a cold front moves through. VFR by late Friday
into Saturday.
&&
.MARINE...
Short Term...Little change to our overall thinking through the
short term forecast period with low pressure passing south and
east of the benchmark tonight and east of Nova Scotia early
Tuesday. This will result in northeasterly winds becoming more
northerly on Tuesday with gales likely in the outer waters...and
some gale force gusts possible in Penobscot Bay. Northwesterly
winds begin to diminish Tuesday night with waves subsiding as
well with high pressure building into the region from the west.
Long Term...SCA conditions will be likely Wed night and Thu as
low pressure lift to the north of the waters resulting in a
stiff southwesterly flow developing. A cold front will pass
across the waters Thursday night, with NWly SCA winds likely
through Friday - with low end gales not out of the question.
&&
.TIDES/COASTAL FLOODING...
High astronomical tides will occur this week. First potential
minor coastal flooding threat comes Tuesday morning with a 11.2
foot tide at Portland. Less than one foot of surge is
advertised in association with offshore coastal low...with
nearshore waves 5-7` with a period of 9-10 seconds. This may
result in some very minor beach erosion and confidence is not
high enough at this time to issue a coastal flood advisory. Will
have the overnight shift take one final look...with a statement
outlining this minor flood potential possible.
Water levels will need to be monitored with southerly winds
ahead of approaching system on Thursday. Astronomical tides peak
that day (11.6 feet in Portland Harbor).
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory from 10 PM this evening to noon EST
Tuesday for ANZ153.
Gale Warning until 1 PM EST Tuesday for ANZ150-152-154.
Small Craft Advisory from 10 PM this evening to 7 PM EST
Tuesday for ANZ151.
&&
$$
NEAR TERM UPDATE...Kimble
SHORT TERM...Arnott
LONG TERM...Ekster
Area Forecast Discussion
National Weather Service Wilmington NC
1030 PM EST Mon Jan 29 2018
.SYNOPSIS...
Low pressure will continue to move northeast, away from the area
and towards New England into Tuesday. Chilly temperatures are
expected Tuesday into Wednesday as high pressure builds into the
Carolinas. Southerly winds behind departing high pressure will
bring a quick warmup beginning Thursday with showers perhaps
returning Friday. Another chance for rain arrives Sunday after a
brief reprieve Saturday.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 1000 PM Monday...Drier air advecting into the area from
the west has brought an end to the light rain and drizzle which
plagued the area through the day. Some low clouds still exist
along the coast, but these will erode as well leaving mostly
cloudless sky conditions for the next few hours. Although KBBP
has reported fog recently, latest LTX VWP suggests low-level
winds are too strong for fog, which combined with the dry
advection occurring has precluded any fog mention in the wx
grids.
The most significant change for the overnight period is the
introduction of some light showers moving west to east from
about 2am through early on Tuesday. These showers are associated
with a strong shortwave within the longwave trough axis, and
represents the onset of strong cold advection and much lower
mid-level thicknesses. As this shortwave lifts across SE NC, it
is accompanied by strong PVA and increasing moisture between
900mb and 700mb. Temperatures will be cooling during this time
as well. Soundings on both the latest RAP and NAM BUFR have
deeper moisture than previous runs, but the top of the saturated
layer is only around -12C, the bottom of the dendritic growth
zone. This combined with a deep warm layer up to 3000 ft and dry
air likely favoring sublimation has prompted the Wx-type to
remain simply RW-, although some snow flakes to our north are
possible. If a stray snow flake did mix in, especially across
Robeson or Bladen counties, it would not stick and not create
any impacts. Lows will end up in the low to mid 30s for most
areas.
High pressure to the west builds over the area on Tue with 5h trough
axis exiting east. Low levels dry out late tonight and skies should
be mostly cloud free tomorrow after the shortwave passage by
late morning. Precipitable water will be be under 0.20" and
approaches 0.10" as the period ends. Strong cold advection continues
through much of tomorrow morning. Despite full sun temperatures
will struggle to reach mid 40s in many areas. Forecast
soundings showing almost 30 kt at the top of the mixed layer
during the day tomorrow and northwest winds are likely to become
rather gusty from late morning through mid afternoon.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 3 PM Monday...Cold advection Tuesday night will be strong
enough to drive low temperatures down into the lower 20s; some 10
degrees below climatology. CAA shuts down on Wednesday but the
surface high builds overhead. This will lead to shallow mixing and
prevent the area from benefiting from the thermal reversal at the
surface and so the afternoon will remain unseasonably cool (though
minus Tuesday`s chilly wind). The high moves partially off the
coast Wednesday night allowing for a slight southerly breeze to
persist and preventing ideal radiational cooling. Low temperatures
will run closer to but still a little shy of climatology.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 3 PM Monday...Mid level troughing will be the main storyline
for the extended period. This pattern will yield a couple of
chances of rain with models trending toward the later system as
the better chance.
Guidance still shows an initial system moving across Friday which
will be moving fast and seemingly starved for moisture. We continue
to advertise chance pops with this feature. A bit of a break for
Saturday before both branches of the jet get active again with mid
and upper level dynamics producing rain both Sunday and Monday.
There are still some timing issues to be ironed out so both days
have some mention of pops. Temperature trends remain mostly intact
with changeable conditions. Warm at first, followed by a brief
cooldown then a slight moderation late.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
As of 00Z...Stubborn MVFR ceilings will finally scatter out from
west to east over the next six hours. Cold air advection is in full
swing with falling dewpoints and gusty north winds. An upper vort
will rotate through overnight. Any precip associated with it will
likely be north of the CWA. Tuesday, scattered skies with a gusty
northwest wind.
Extended Outlook...VFR though Sat. Chance showers Fri.
&&
.MARINE...
NEAR TERM /THROUGH TUESDAY/...
As of 1000 PM Monday...Northwest winds beginning to increase
across the waters and will continue to do so through Tuesday as
cold advection intensifies. Gusts of 25 kts are likely
overnight, and may approach gale force at times during Tuesday.
The offshore winds are not typically conducive to 6 ft seas
across the coastal waters, with the exception being near the
20nm boundary of the NC waters which experience slightly longer
fetch. Otherwise, seas will be 3-5 ft, lower near shore, through
the period. Despite these lower wave heights, the ongoing SCA
remains unchanged as winds will exceed 25 kts much of Tuesday.
SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 3 PM Monday...The moderately strong post-frontal gradient
flow will begin to gradually ease Tuesday night. This could mean
that as Advisory gets lowered we will need to carry SCEC headlines
for a time. Rapid improvement then slated for Wednesday as the high
moves overhead. This high shifts partially offshore Wednesday night
bringing SW winds capped at 10kt and seas no greater than 2 ft.
LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 3 PM Monday...Changeable conditions for the marine community
for the extended period. A strengthening southwest flow will be in
place Thursday reaching 15-20 knots briefly before cold front moves
across Friday. Cold air advection will allow north to northeast
winds to increase to 15-20 knots for a few hours later Friday before
the gradient relaxes and the cold air advection ends Saturday. A
weak return flow will commence by the end of the period. The
changeable fetch will prevent significant seas from building
appreciably with mostly 2-4 feet expected.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory from 6 AM to 8 PM EST Tuesday for AMZ254-
256.
Small Craft Advisory until 8 PM EST Tuesday for AMZ250-252.
&&
$$
SYNOPSIS...SHK
NEAR TERM...JDW
SHORT TERM...MBB
LONG TERM...SHK
AVIATION...JDW/DL
MARINE...
Area Forecast Discussion
National Weather Service Lincoln IL
846 PM CST Mon Jan 29 2018
.UPDATE...
Issued at 846 PM CST Mon Jan 29 2018
Updates this evening have been for progression of clearing skies
as high pressure moves toward the central IL area from the upper
Midwest. As of 830 p.m. cloud covered areas are from Danville to
Shelbyville southeastward, with clearing expected throughout
central and southeast IL by midnight. Northwest winds are
diminishing as expected, ranging generally 4 to 8 mph in the
northwest to 10-15 mph in the southeast, and these should continue
to gradually decrease overnight, becoming only a few mph or even
calm by morning. Temperatures as of 8 p.m. range from 17 in Lacon
under clear skies to 30 in Flora under continued cloud cover.
Temperatures should fall to the teens across the area tonight, as
low as 10 degrees around Galesburg.
&&
.SHORT TERM...(This evening through Tuesday)
ISSUED AT 320 PM CST Mon Jan 29 2018
The surface trough has been slow to depart this afternoon, and
flurries/clouds are holding on longer. Satellite and radar trends
are indicating we should see the clearing at least in our western
counties as sunset approaches. HRRR output is showing clouds
gradually dissipating in place across central Illinois between 00z
and 04z/6-10pm. Eastern counties look to finally clearing out by
late evening.
High pressure advancing into the area will provide decreasing
winds and mostly clear skies the last half of the night. The very
low dewpoints upstream point toward a cold night tonight, so we
undercut guidance by a couple degrees to trend colder. Lows near
Galesburg will approach 10 degrees, while areas toward
Lawrenceville bottom out in the upper teens.
Sunshine will start out the day tomorrow, but mid to high clouds
will begin streaming into western Illinois during the afternoon,
as southerly winds develop. The cold airmass will be slow to
respond to the warming southerly flows, with highs mainly in the
low to mid 30s, with areas near Jacksonville possibly reaching the
upper 30s.
.LONG TERM...(Tuesday night through Monday)
ISSUED AT 320 PM CST Mon Jan 29 2018
Brisk southerly winds will highlight the forecast Tuesday night
into Wednesday, with wind gusts of 25-35 mph at times. Despite a
predominance of clouds during that time, temperatures look to
steadily warm. A diminished diurnal temperature swing will start
Tuesday night, with late night temps possibly rising after
midnight. Highs on Wednesday look to rise into the mid 40s to low
50s. Winds will diminish Wed afternoon as a cold front enters into
western Illinois. Slight chances of rain are projected to develop
ahead of that front in east-central Illinois, closer to the better
energy and forcing for precipitation due to the parent low
pressure being in eastern Ontario at that time. Better chances of
precipitation look to come in the southeast half of our forecast
area Wed night and Thursday as the cold front pushes across
Illinois, which includes mainly south of I-72. Rain will
gradually change to snow Wed night, then begin to transition back
to rain on Thursday as precipitation becomes mainly confined to
south of I-70. Some light snow accumulation will be possible, but
most areas in southeast IL will just see trace amounts or a
dusting of snow. Slippery conditions could still develop on
bridges and overpasses, however.
The break in precipitation is forecast for Thursday night through
Saturday morning, as very cold air settles into the area. Lows
Thursday night look to drop into the single digits in many areas,
with low teens south of I-70. Some warming is projected for
Saturday ahead of the next cold front, with highs reaching the
upper 30s to low 40s, before the cold front passes Saturday
evening. Light rain is expected to develop Saturday afternoon
north of I-72, with a rain-snow mix possible north of I-74.
Precipitation will become likely Saturday night with the cold
FROPA, as any lingering rain showers change to snow. The snow
looks to come to an end by sunrise on Sunday, with snow amounts of
an inch or two possible.
A reinforcing push of very cold air will follow that cold front.
The surface high is expected to shift across Illinois on Sunday
night, allowing for clearing skies and weakening winds. Lows
Sunday night will drop into the single digits in most areas again,
especially over any areas that receive a snow cover Saturday
night. Monday should be mostly sunny but chilly, with highs in
the mid 20s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 545 PM CST Mon Jan 29 2018
MVFR conditions will linger for a few hours past 00Z from KBMI-
KMTO eastward, then clearing will progress from west to east
throughout the central IL terminals with skies SKC-SCT200 through
00Z Tuesday. Winds NW 6-12 kts becoming light and variable
overnight. Winds shifting to southerly and increasing to 10-12 kts
after 18Z.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...37
SHORT TERM...Shimon
LONG TERM...Shimon
AVIATION...37
Area Forecast Discussion
National Weather Service New York NY
1017 PM EST Mon Jan 29 2018
.SYNOPSIS...
Low pressure will pass well south and east of the region
overnight and move into the Canadian Maritimes on Tuesday. High
pressure builds into the area Tuesday night into Wednesday. A
series of frontal systems will then impact the area, the first
Thursday into Friday, and then another on Sunday. Each of these
systems will be followed by high pressure and a shot of cold
air.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
A sharpening northern stream trough will approach the region
tonight, while low pressure tracks well southeast of the
region.
Increasing confidence in a light accumulating snow for Eastern
LI and SE CT tonight into Tuesday morning in deformation zone
ahead of approaching shortwave energy and well NW of low
pressure.
00z NAM has come into better line with GFS/GEM/ECMWF/SPC HREF
signal of 1-2 tenths of an inch qpf across eastern LI/SE CT.
HRRR has been consistent in in showing a band of light snow
across Suffolk County and SE CT. Western edge of accumulating
snowfall is a bit tricky, in general proximity of Nassau and
New Haven Counties.
Based on precip shield development seen on radar and above model
agreement, have increased snowfall amounts for E LI/SE CT with
around 1 to locally 2 inches of snow expected overnight into
Tuesday morning. There is a one in ten chance for 2 to 3 inches
across this area. Farther west, a period of light snow or some
light snow showers possible, but not expecting much than a
dusting of snow.
Cold advection overnight and any steadier precip will quickly
change any mixed precip to snow. With initially some wet roads,
especially across E LI, giving way to temps in the mid to upper 20s
by Tuesday morning, untreated surfaces are expected to be snow
and ice covered for the Tuesday morning commute.
Overnight lows fall into the middle and upper 20s, with near 30
in and around the NYC metro.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
An upper level shortwave approaches from the west on Tuesday,
which could provide some additional snow, mainly west of NYC. It
is possible the snow, could be in the form of snow showers. If
this does occur, a few snow squalls could potentially produce a
brief period of lower visibility and a quick coating of snow on
the ground. High temperatures rise into the lower and middle
30s.
Drier weather is expected Tuesday night as high pressure
ridging builds into the region. Lows Tuesday night fall into the
teens and lower 20s.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
High pressure ridge shifts through the region on Wednesday with dry
weather and highs generally in the mid 30s. Low pressure then tracks
through SE Canada Wednesday night through Friday. Overrunning PCPN
will be possible late at night into Thursday morning mainly north
and west of the city. Chances increase further Thursday afternoon
with the rest of the tri-state area having a chance for PCPN. As for
PCPN type during this period, primarily rain for coastal areas and a
wintry mix of snow, sleet and freezing rain will be possible with
warm air aloft. A cold front associated with this weather system
pushes through Thursday night. Have gone with likely PoPs for this
period with rain in the evening and a mix of rain and snow during
the overnight hours. Light snow accumulations are expected.
A chance of lingering snow remains Friday morning, otherwise dry in
the afternoon with high pressure building in behind the cold front.
High pressure then keeps Saturday dry with below normal temperatures.
Another low pressure center is then progged to pass to the north -
this time tracking along the St. Lawrence River Valley Saturday
night and Sunday. Antecedent airmass is colder this time around, so
in spite of a SW flow ahead of a cold front that passes through
Sunday into Sunday night, it looks like at this point that PCPN
types would favor more on the wintry side. How far this cold front
moves offshore is still in question as well as whether or not a wave
of low pressure forms along the front and brings some PCPN to the
area during Monday. Will go with dry weather for Monday and wait and
see how models trend before introducing PoPs.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Low pressure passes well offshore tonight and tracks toward the
Canadian Maritimes Tuesday.
VFR conditions are expected, with MVFR ceilings expected at times
overnight and through Tuesday morning. IFR visibilities are also
possible in light snow, especially east of NYC terminals overnight
and into the morning hours.
During the late morning and afternoon Tuesday, generally VFR
ceilings are forecast, but cannot rule out a snow shower, which
could result in MVFR or brief IFR. Low probability though of this
occurring.
NE winds 10-15 kt back to the north overnight and into Tuesday
morning. These winds then back to the NW 10 kt or less in the
afternoon.
.OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY...
.Tuesday night...VFR with skies clearing. NW winds G15-20KT.
.Wednesday...VFR.
.Thursday...Mainly VFR...Slight chance of wintry mix inland.
.Thursday night-Friday...MVFR/IFR possible in rain or snow. Any
wintry precip ends by Friday afternoon. NW gusts 15-20KT on Friday.
.Saturday...VFR.
&&
.MARINE...
Gusts peak at 30 to 35 kt across ocean waters and eastern
nearshore waters overnight as low pressure passes nearby, with
seas running 6 to 12 ft on the ocean. Winds and seas will begin
subsiding late tonight into Tuesday morning, but likely
remaining at SCA levels into Tuesday Night.
SCA conds continue into a portion of Wednesday with a brief period
of sub-advisory conditions during the afternoon and evening hours.
Winds and seas then pick up again Wednesday night into Thursday with
a returns to SCA conds for at least the ocean waters. Periods of SCA
conds will then occur through Friday night. A high pressure ridge
should then provide relatively tranquil conditions on all waters
during Saturday.
&&
.HYDROLOGY...
No significant hydrologic issues are anticipated through next
week.
&&
.TIDES/COASTAL FLOODING...
The combination of an approaching full moon, high astronomical
tides, and NE/N SCA winds will result in minor coastal flooding
around the time of high tide Tuesday morning. A surge of 1 to 1
1/2 feet is expected. A blend of guidances was used, with the
most susceptible area being the south shore bays of Western
LI/Queens, the Lower NY/NJ harbor, and western LI sound, with
brief isolated impacts elsewhere.
&&
.EQUIPMENT...
NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the
air for an extended period of time.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Coastal Flood Advisory from 9 AM to 11 AM EST Tuesday for
CTZ009.
NY...Coastal Flood Advisory from 9 AM to 11 AM EST Tuesday for
NYZ071-078-177.
Coastal Flood Advisory from 5 AM to 10 AM EST Tuesday for
NYZ178-179.
NJ...Coastal Flood Advisory from 5 AM to 10 AM EST Tuesday for
NJZ006-106-108.
MARINE...Small Craft Advisory until 6 AM EST Tuesday for ANZ330-340-345.
Small Craft Advisory until 6 AM EST Wednesday for ANZ350-353-
355.
&&
$$
SYNOPSIS...BC/JC
NEAR TERM...NV
SHORT TERM...BC
LONG TERM...JC
AVIATION...DS
MARINE...BC/JC
HYDROLOGY...BC/JC
TIDES/COASTAL FLOODING...
EQUIPMENT...
Area Forecast Discussion
National Weather Service Norman OK
526 PM CST Mon Jan 29 2018
.AVIATION...
VFR conditions will continue. A southerly surface wind will
prevail across western Oklahoma through the period. Meanwhile,
light and variable winds across central Oklahoma and western north
Texas will gradually shift to the south this evening and overnight.
A gusty south wind is expected at all sites on Tuesday.
&&
.PREV DISCUSSION... /issued 322 PM CST Mon Jan 29 2018/
DISCUSSION...
Primary forecast focus is on increased fire weather concerns Tuesday
and Wednesday.
This afternoon, temperatures have trended upward over the past few
hours, with most sites finally reaching the 40s. We`ve had a few hot
spots crop up on GOES East with some confirmation via social media
of brief fires, given elevated conditions. Luckily, north winds have
continued to relax through the afternoon.
The broad surface ridge will slide eastward overnight, with weak
winds gradually veering to the south/southeast, through early
Tuesday, as another surface trough slides eastward off the western
high plains. This will result in weak warm air advection, with a
minor recovery of dew points, into central and western Oklahoma.
Short-range guidance has consistently shown an axis of upper 20s
near 30 dew points developing between the US 81 and I-35 corridors.
Winds will begin to veer to the south and southwest until early to
mid afternoon. This bodes well for keep RH values in the 20s, with
15 to 20 percent RH values reserved for far western Oklahoma and
western north Texas. With all of that said, the grander issue is
fuels. ERC-G values are nearing the 90th percentile, the drought
conditions are no joke. Did not upgrade the watch to red flag at
this time. Confidence in red flag conditions developing fully
remains somewhat low. If an upgrade is needed tonight, it may only
be the far western row or two of counties.
Wednesday is a bit tricky, as the surface trough begins to progress
south/southeast into the Panhandles and northern Oklahoma. South
winds will remain elevated through the early morning, with the wind
shift beginning around Noon in far northwestern Oklahoma and
gradually building to the south through the day. Ahead of the front,
southwestern Oklahoma and western north Texas will experience a bit
of a January pre-frontal torch, with strong southwest winds and
afternoon highs approaching the upper 70s near 80. Made no changes
to the going fire weather watch for southwestern Oklahoma and
western north Texas for Wednesday at this time.
Beyond Wednesday, the forecast is a bit more seasonably mild, with
cooler highs as the plains remain under the influence of a broad
surface ridge stretching across the plains and gradually shifting
eastward through Friday. Warm air advection will return into
Saturday, as a surface trough develops in response to an approaching
500mb shortwave across the Colorado Rockies. The GFS remains the
more bullish guidance with respect to precipitation development. The
ECMWF is a bit more reserved, likely due to it`s weaker resolution
of the strength of the 500mb trough and it`s influence on moisture
return from the Gulf. With that said, regardless of the solution,
neither is a "drought buster," the resident phrase of the week. If
anything, given temperatures, we could see some light rain and maybe
some light snow late Saturday night/early Sunday. Any precipitation
would likely develop along or east of the I-35 corridor, with the
best chances into eastern Oklahoma.
Kurtz
PREV DISCUSSION... /issued 528 AM CST Mon Jan 29 2018/
DISCUSSION...
Aviation discussion for the 12 UTC TAFs is below.
AVIATION...
VFR conditions are expected to continue.
Northerly surface winds will weaken then turn to the south
at most sites over the next 24 hours.
MBS
PREV DISCUSSION... /issued 442 AM CST Mon Jan 29 2018/
DISCUSSION...
Fire weather potential, especially Tuesday and Wednesday, remains
the main concern.
The biggest changes to the previous forecast were to issue a Fire
Weather Watch across all of western north Texas and parts of
southwestern Oklahoma on Wednesday as well as to slightly expand
the Fire Weather Watch on Tuesday eastward.
No precipitation is forecast across the Norman Forecast area now
through next Sunday.
Today, cooler weather will prevail as a cold front moved through
the area overnight. Most models depicted lower temperatures than
previously forecast, which seems reasonable, generally ranging
from the lower 40s near Ponca City to the mid 50s near Knox
City, Texas. Abundant sunshine and decreasing surface winds can
be expected today. Used the lower HRRR model surface dewpoints
which seemed to be accurate.
Tonight, preferred the colder side of guidance lows, closer to the
00 UTC METMOS numbers due to a surface high overhead along with
mostly clear skies and light surface winds.
Tuesday, breezy to windy and warmer conditions will occur.
Some model guidance has suggested that gusts in the 40 to 45 mph
range could occur by afternoon across parts of western Oklahoma,
mainly near Clinton, Weatherford, Watonga, and Woodward. Thus, a
Wind Advisory may be necessary. Model guidance highs with highs
mainly in the 50s and 60s appeared reasonable.
Wednesday, a weak dry cold front will move into Oklahoma and
perhaps western north Texas. Above average temperatures will
continue with the warmest readings south of the front, which may
not be too far from daily record high temperatures (78F at Wichita
Falls and 77F at Lawton). Surface winds will be strongest south
of the front as well.
Wednesday night into Thursday, cooler weather will return to
Oklahoma and north Texas. There may be enough low level moisture
for drizzle and/or light rain near Durant Thursday morning
(depicted by latest NAM and GFS model runs), but did not mention
due to very low confidence.
Thursday night through Sunday, dry weather will likely continue.
Confidence is growing that a reinforcing cold front will bring
colder weather sometime Saturday and Sunday based on latest
model guidance. Precipitation chances remain too low to mention
at this time.
MBS
FIRE WEATHER...
Cooler conditions along with light surface winds will allow for
lower wildfire danger today. However, the air will remain
quite dry with low humidity. ERC values remain very high,
generally 75th percentile to near daily maximums across Oklahoma
and north Texas due to the recent dry weather.
On Tuesday, expanded the Fire Weather Watch eastward mainly
because of the strong southerly surface winds expected which may
overcompensate for the somewhat cool temperatures and relative
humidity values that may stay just above 20%. There is concern
that model surface dewpoints may be too high. Deferred upgrading
to a Red Flag Warning at this time to allow for the dayshift
to examine more data and time to collaborate with core fire
weather partners.
Wednesday, issued a Fire Weather Watch for western north Texas
and southwestern Oklahoma, south of surface cold front and
near/west of surface dryline where strong surface winds, near
record temperatures, and low humidity are forecast. The exact
location of this cold front and dryline remain uncertain, which
may make a significant difference in regards to the strength of
surface winds.
Cooler temperatures are expected to bring lower wildfire danger
Thursday into next weekend.
MBS
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 27 59 43 68 / 0 0 0 0
Hobart OK 29 63 43 71 / 0 0 0 0
Wichita Falls TX 28 65 44 75 / 0 0 0 0
Gage OK 31 69 38 62 / 0 0 0 0
Ponca City OK 24 57 38 63 / 0 0 0 0
Durant OK 28 56 41 68 / 0 0 0 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Fire Weather Watch from Tuesday morning through Tuesday evening
for OKZ004>006-009>011-014>018-021>024-027-033>039-044-045.
Fire Weather Watch from Wednesday morning through Wednesday
evening for OKZ037>039-044-045.
TX...Fire Weather Watch from Tuesday morning through Tuesday evening
for TXZ083>090.
Fire Weather Watch from Wednesday morning through Wednesday
evening for TXZ083>090.
&&
$$
Area Forecast Discussion
National Weather Service Seattle WA
355 PM PST Mon Jan 29 2018
.SYNOPSIS...The cold front that has been preceded by today`s heavy
rain will exit Western Washington early this evening. Heavy rain
will end with the front`s exit, and the front will be followed by
showers and lower snow levels tonight through Wednesday. Rain and
mountain snow will become more steady on Thursday as a warm front
passes the area. Mild temperatures and light rain will prevail
from Friday through next Monday as we sit under the dirty
periphery of a flat upper ridge.
&&
.SHORT TERM...Heavy rain has been underway today over much of the
forecast area due to an atmospheric river type setup. UIL (near
Forks) has measured over 5 inches of rain in the past 24 hours. A
cold front is currently slipping south through Western Washington
and is currently located along a line from Grays Harbor to
northern Whidbey Island to Blaine. Heavy rain continues to the
southeast of the front. The front should exit the southeast corner
of the forecast area around 6-7 pm, bringing the heavy and
hydrologically significant rainfall to an end.
Behind the front, convective post-frontal showers will spread in
and continue into Wednesday, with onshore flow focusing showers
over the mountains and in any Puget Sound Convergence Zone (PSCZ)
that develops. Snow levels will drop quickly this evening,
falling to near 2000 feet overnight and to 1500 feet or less on
Tuesday night. Advisory amounts of snow are forecast in the
mountains tonight (6-11 inches), with additional snowfall on
Tuesday that could bring 24 hour snow totals into the 8-17 inch
range. Heaviest amounts are expected near Mount Rainier. PSCZ
could reach near Stevens Pass on Tue PM, enhancing snow there
later in the day.
Flat upper ridging offshore on Thursday will help to spread a
classic warm front into Western Washington. This means an increase
in widespread stratiform rain over the lowlands on Thursday, with
mountain snow. East-southeast gradients will mean breezy and windy
conditions over the coast and near Whidbey Island. Haner
.LONG TERM...From Friday through next Monday, models keep a
pattern of light rain and mild temperatures in place, though
Friday morning could be the least wet period of the longer term
forecast. A flat upper ridge will persist around 130W-135W during
this period. Western Washington will be in the "dirty" periphery
of this feature, with a steady dose of warm advection lift and
light rain. Flow aloft will be west- northwest during this period,
which is favorable for shadowing the Central Puget Sound region,
including Bremerton and Seattle. For the rest of the region, would
describe this period as drippy and mild, perfect for the
burgeoning moss garden. Haner
&&
.AVIATION...A cold front aligned nearly north-south is currently
right over Puget Sound and moving slowly southeast. Moderate
westerly flow aloft will develop behind the front tonight and
continue through Tuesday. Moderate southerly gradients will become
more onshore tonight and continue Tuesday. The air mass is moist and
stable.
Several hours of MVFR ceilings, mostly 1-2k ft, will be associated
with the frontal rain this evening. Visibilities will be 3-5sm. VFR
ceilings will return tonight and should prevail Tuesday. Widespread
rain will change to scattered showers by this evening. A convergence
zone may form this afternoon and evening in Snohomish County.
KSEA...Ceilings should become MVFR 1-2k ft shortly, with some
visibility restriction in moderate rain. Improvement to VFR is
likely to begin around 03Z. Southwest wind 10g20 kt is likely
through the evening, easing somewhat later tonight. CHB
&&
.MARINE...A cold front is just about through the area at 2 PM. Small
craft advisory strength southwesterly winds will continue over all
waters, except for westerly winds in the strait. Winds in the strait
could touch gale force later this afternoon or this evening. Onshore
flow through Tuesday will keep winds at advisory levels much of the
day into Tuesday evening. Westerly swell will build to 15 to 17 feet
tonight and will persist through Tuesday.
Flow will remain onshore Tuesday, then ease Wednesday. Another front
will arrive Thursday, with gales possible over most waters. Onshore
flow will resume Friday and Saturday. CHB
&&
.HYDROLOGY...The Skokomish River in Mason County is expected to
remain above flood stage for the next 2-3 days. Moderate flooding
is now forecast, and major flooding cannot be ruled out.
Heaviest rainfall has started shifting slowly southeast this
afternoon. In fact, the North Coast appears to now be in
hydrologically insignificant post-frontal showers. The 22z HRRR
shows the heaviest, hydrologically significant precip exiting the
Mount Rainier area soon after 6 pm. Snow levels will also be
falling this evening, eventually falling to 2000 feet overnight.
So runoff from mountain headwaters will really taper off after 6
pm, though there will still be plenty of water within the river
systems to route downstream. This process can take 1-3 days,
depending on the basin, so the Flood Watch continues for rivers
coming out of the Olympics and North Cascades, i.e. from Snohomish
County northward and the Olympic Peninsula.
Soils are rather saturated across much of Western Washington as a
result of recent rainfall. The addition of today`s heavy rainfall
may result in the production of some shallow landslides across
the area. A landslide Special Weather Statement has been issued
and provides additional information and links.
Once flooding stemming from today`s rainfall has ended, additional
flooding is not expected on area rivers through next Monday.
Haner
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory from 6 PM this evening to 10 AM PST
Tuesday for Cascades of Pierce and Lewis Counties-Cascades
of Snohomish and King Counties-Cascades of Whatcom and
Skagit Counties.
Flood Watch through Tuesday afternoon for Admiralty Inlet Area-
Bellevue and Vicinity-Cascades of Snohomish and King
Counties-Cascades of Whatcom and Skagit Counties-Central
Coast-East Puget Sound Lowlands-Eastern Strait of Juan de
Fuca-Everett and Vicinity-Hood Canal Area-Lower Chehalis
Valley Area-North Coast-Olympics-Western Skagit County-
Western Strait of Juan De Fuca-Western Whatcom County.
PZ...Small Craft Advisory for rough bar until 4 PM PST Tuesday for
Grays Harbor Bar.
Small Craft Advisory until 10 PM PST Tuesday for Coastal Waters
From Cape Flattery To James Island 10 To 60 Nm-Coastal
Waters From Cape Flattery To James Island Out 10 Nm-Coastal
Waters From James Island To Point Grenville 10 To 60 Nm-
Coastal Waters From James Island To Point Grenville Out 10
Nm-Coastal Waters From Point Grenville To Cape Shoalwater
10 To 60 Nm-Coastal Waters From Point Grenville To Cape
Shoalwater Out 10 Nm-Northern Inland Waters Including The
San Juan Islands-West Entrance U.S. Waters Strait Of Juan
De Fuca.
Small Craft Advisory until 4 AM PST Tuesday for Central U.S.
Waters Strait Of Juan De Fuca-East Entrance U.S. Waters
Strait Of Juan De Fuca-Puget Sound and Hood Canal.
Small Craft Advisory until 10 PM PST this evening for Admiralty
Inlet.
&&
$$
www.weather.gov/seattle