Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/12/18
Area Forecast Discussion
National Weather Service Albany NY
945 PM EDT Wed Apr 11 2018
.SYNOPSIS...
An upper level disturbance will allow for some passing
light rain and snow showers through midnight. After a dry
morning, a warm front will bring some light rain to the region
tomorrow afternoon, along with milder temperatures. Friday will
be a mild day, although much colder air will return for over the
weekend, along with some rain and freezing rain, as a cold
front drops down from the north.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
As of 930 PM EDT, clouds are filling back in from west to
east, as a weak upper level shortwave trough currently moving
across central/western New York continues translating east
across the region.
Based on the 3km HRRR and NAM, spotty light showers of
rain/snow should continue increase in areal coverage once again
through about midnight or so, especially across higher
elevations, as the shortwave continues to cross the region.
Even though temps aloft are chilly, boundary layer temps will
initially allow for P-type to generally be rain showers for
most valley areas. However, as wet-bulb effects occur, high
terrain areas should see precip changing to snow, which could
leave a light coating on grassy and non-paved surfaces. Some
snow could even mix in for valley areas briefly as well before
tapering off. Total QPF looks mainly to be just a few hundredths
of an inch for most areas.
Once spotty precip ends around midnight, skies should start to
clear out as the shortwave slides eastward. Low temps will drop
into the upper 20s to mid 30s across the region by daybreak.
There could be a little patchy fog developing late tonight in
any sheltered valley areas where rain showers/sprinkles occur
prior to midnight.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
Active and changeable weather is expected through the short term
period with fast zonal flow in place. Although the day will
start off dry on Thursday, isentropic lift ahead of an
approaching warm front will return some widespread light rain to
the region for Thursday afternoon through Thursday late evening,
as surface low pressure lifts across the Great Lakes. Best
chance of seeing the steadier precip will be for areas north of
the Mohawk Valley. Both temps aloft and boundary layer temps
will be warm enough for any precip to be in the form of plain
rain. Highs on Thursday look to be in the 50s for most areas,
although some high terrain parts of the Adirondacks may only
reach the mid to upper 40s.
Precip will be ending on Thursday night as low pressure slides
by to the north. However, this front will be stalling just to
our south and will be returning back north on Friday as a warm
front. So, while temps should quickly cool down in the 30s and
40s on Thursday night, they will be warming back up for Friday,
especially for southern areas. There will be a large temp
gradient across the area for Friday, as northern areas will only
get into the warm sector by late in the day. Highs will only be
in the mid 40s to upper 50s for northern areas, and should be as
warm as the mid 60s to low 70s for southern areas, where there
should be breaks of sun for most of the day. Some additional
light rainfall is possible for Friday, mainly for northern
areas, as the boundary slowly works it way back northward.
This front look to stall once again on Friday night, although
the exact positions of this is still unknown. It will probably
be somewhere across the Adirondacks, although the model guidance
still is varying on this. For now, have gone with lows on Fri
night in the upper 30s to mid 40s for northern areas, and upper
40s to mid 50s for southern areas, with the most clouds closest
to the frontal boundary across the northern half of the region.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
...Multi-hazard storm system to impact region Saturday night-
Monday...
Multiple upper level jets will undergo significant amplification
this weekend, with a strong northern stream impulse tracking east
across central/eastern Canada, while another strong impulse ejects
from the southern/central Rockies into the Plains. As this southern
system amplifies, strong ridging will develop downstream across the
western Atlantic Ocean.
Very strong upper level confluent flow will develop across southeast
Canada, supporting a strengthening surface high across south central
Canada. Very cold air will be drawn southward from this high,
although the southern fringe of the cold airmass will become rather
shallow.
In response to these upper level features, a frontal boundary will
develop across the region Saturday, and as the high to the north
strengthens, expect shallow cold air to seep southward, especially
in north/south valleys. To the south of the frontal boundary, a very
warm air mass will be in place, so afternoon highs on Saturday could
reach into the 70s, if not higher, in some southern valley areas.
Meanwhile, temperatures may briefly rise into the 40s and 50s to the
north, before falling into and through the 40s and 30s later in the
day, first across the upper Hudson Valley region. Some showers may
develop on the cold side of the boundary, as upper level energy and
remnant convection from the Great Lakes spills eastward.
Then, for Saturday night into Sunday, lots of uncertainty on how far
south the cold air reaches, but there is at least some possibility
for low temperatures by Sunday morning to fall into the 20s across
portions of the southern Adirondacks and Lake George Region, and
portions of southern VT, with lower potential to reach as far south
as the Mohawk Valley. Some isentropic lift north of the surface
front may lead to periods of light rain, freezing rain and sleet,
with best chances of freezing rain mainly at night due to
significant diurnal effects in mid April.
For Sunday night-Monday, the main storm system with an occluded
front will approach slowly from the west/southwest, with possible
waves of low pressure tracking along it. The upper level system may
become negatively tilted, slowing the front`s eastward progress.
This could lead to periods of heavy rain, with latest 12Z/GEFs
suggesting high probabilities of 1 inch or greater QPF over 24 hours
(ending Monday night), with even some potential for 2" over 36
hours. Trends will need to be watched closely to assess possible
impacts from this heavy rain, combined with snowmelt.
Strong east/southeast winds will be possible Sunday night into
Monday across higher terrain areas of the southern Greens,
Berkshires and Taconics.
As for temperatures, sided colder than a model blend for Sunday
night-Monday, with lows mainly in the 30s, although some 20s could
occur across portions of southern VT. Highs Monday mainly in the 30s
and 40s, and would not be surprised if lingering pockets of freezing
rain occur well into the morning for some elevated areas within
southern VT and eastern Berkshire Co MA.
In the wake of the storm system, quite a bit of rain/snow showers
expected later Monday night through Tuesday. Another fast moving low
pressure system could bring some rain to the region later Wednesday.
Highs Tue-Wed mainly in the 30s and 40s, with lows mainly in the 20s
and 30s.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
A weak upper level disturbance will cross the region this
evening, bringing a few passing light showers of rain or snow. A
stronger upper level disturbance and warm front will bring some
rain to the TAF sites Thursday afternoon and early evening.
VCSH will end this evening and tonight between roughly 03Z-06Z.
Most of these showers should remain north of KPOU. Expect the
skies to quickly clear between midnight and daybreak with VFR
conditions Thursday morning and early afternoon. However, will
have to watch for any patchy ground fog to develop at KGFL if
any showers occur this evening.
Rain is expected to overspread the TAF sites Thursday afternoon,
with the steadiest and most persistent rain expected at KGFL.
Areas of MVFR Cigs, with MVFR/IFR Vsbys will be possible, esp at
KGFL later in the afternoon.
West to southwest winds around 5-10 KT early this evening
should trend to calm overnight. Winds will become south to
southwest Thursday morning at 5-10 KT, and increase to 8-14 KT
in the afternoon, with some gusts of 20-25 KT or slightly higher
possible, especially at KALB.
Outlook...
Thursday Night: Moderate Operational Impact. Chance of RA.
Friday: Moderate Operational Impact. Chance of RA.
Friday Night: Low Operational Impact. Slight Chance of RA.
Saturday: Moderate Operational Impact. Chance of SHRA.
Saturday Night: High Operational Impact. Likely RA.
Sunday: High Operational Impact. Likely RA.
Sunday Night: High Operational Impact. Definite RA.
Monday: High Operational Impact. Definite SHRA...RA.
&&
.FIRE WEATHER...
High terrain areas continues to have a snowpack in place, while
valley areas are generally clear. Although it will be fairly
quiet tonight, a period of rain is expected tomorrow thanks to
a warm front, which will allow for elevated RH values (generally
50 to 70 percent) and southerly winds of 5 to 15 mph. Northern
areas will see in excess of a quarter inch of rainfall.
Additional rainfall is expected over the weekend and into early
next week, some of which may be locally heavy.
&&
.HYDROLOGY...
A few spotty light rain or snow showers are expected this
evening with little total precip amounts. A warm front will
bring some additional rainfall for tomorrow into tomorrow
evening. Although southern areas will see a tenth of an inch or
less, the Adirondacks could pick up a half inch of rainfall,
which may locally allow for some light minor rises on rivers and
streams.
With a brief period of milder temperatures expected, some
snowmelt is expected for late in the week. However, colder
temperatures will return once again for over the weekend and
into early next week. In addition, widespread steady
precipitation (some of which could be heavy) is expected with a
frontal boundary for the weekend into early next week as well.
This rainfall, combined with recent snowmelt, could allow for
some significant rises on rivers and streams. There will be the
potential for some flooding by early next week, although the
exact extent will depend on just how much rainfall and snowmelt
occurs, which is still unknown at this time.
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.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...KL/Frugis
NEAR TERM...Frugis/KL
SHORT TERM...Frugis
LONG TERM...KL
AVIATION...KL/NAS
FIRE WEATHER...Frugis
HYDROLOGY...Frugis
Area Forecast Discussion
National Weather Service Denver/Boulder CO
810 PM MDT Wed Apr 11 2018
.UPDATE...
Issued at 810 PM MDT Wed Apr 11 2018
Main change for this evening is to expand tomorrow`s Red Flag
Warning further northward...see the Fire Weather section below.
Forecast is generally on track, except for more high cloud cover
which will likely continue through Thursday. Also of note is that
at 00z the dew points are about 10 degrees lower than most of the
raw model forecasts and even some of the short-term analysis
products. This is a typical error and MOS picks up on this fairly
well, so I moved the forecast close to the NAM MOS. This results
in lower dew points for Thursday as well, especially in the drier
part of the air mass in our Red Flag area.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 314 PM MDT Wed Apr 11 2018
...CRITICAL FIRE DANGER CONTINUES INTO THE EARLY EVENING HOURS
TODAY WITH EXTREME FIRE DANGER THURSDAY...
...TURNING COLDER FRIDAY WITH STRONG WINDS CONTINUING...
GOES 16 water vapor shows jet pushing to the ESE with increased
subsidence and drying moving over the mountains and adjacent
plains. Main concern continues to be fire weather due to the
continued high winds providing decreased RH values over already
dry grasses and trees. Areas of concern for today are the
foothills, Park county and eastern plains through this evening.
See Fire Weather Section for Red Flag Warning information. Warm
advection continues to be strong with the possibility of a record
high nearing 80 degrees over the Denver area. A weak backdoor cold
front will move onto the NE plains by the late evening hours
ushering in low level moisture and helping to stabilize the winds
over portions of the plains. Wind directions will switch to a more
ESE direction for areas north of I-70 while the surface low over
Jefferson will help to keep winds south of I-70 from the SW and
stronger through Thursday. Areas over the northern foothills could
see a period of heightened fire weather conditions between 3 and
7 pm as winds transition to the NW where more moist and cooler air
resides. Areas over Larimer and portions of western Weld could
get close to Red Flag conditions. Held off from any warnings at
this point but continued vigilance is encouraged.
An upper level disturbance will be moving towards the four corners
region by late Thursday that will help to increase moisture over the
higher terrain by late Thursday. Conditions for Thursday will
continue to be sunny and dry with winds continuing to be high with
gusts between 30 and 40 mph by Thursday afternoon. Temperatures
tomorrow will once again be high with values in the mid to upper 70s
on the plains and 40s to 50s in the mountains.
.LONG TERM...(Thursday night through Wednesday)
Issued at 314 PM MDT Wed Apr 11 2018
Strong spring storm will form over the Central Plains Thursday
night and Friday. It will slowly shift eastward Friday night and
this weekend. Blizzard conditions are expected over parts of South
Dakota and Nebraska. The 12Z NAM shows a band of heavy snow
forming over far eastern Colorado Friday while the ECMWF and GFS
keep the heavy snow to the northeast of Colorado. Main concerns
for north central and northeast Colorado will be mountain snow and
strong winds over the eastern plains Friday. Details below.
Surface low and cold front will push across eastern Colorado
Thursday night. Winds will become westerly during the evening
hours with gusts to 50 mph continuing. As the surface lows shifts
farther east winds will turn northwesterly. The northwest winds
will usher in much colder air for Friday. Temperatures to start
off Friday will be in the lower 40s and upper 30s. Strong cold air
advection will cause temperatures to remain steady or fall during
the day over the eastern plains. It should be cold enough for
snow with any precipitation on the backside of the low. A brief
period of rain will be possible during the onset of precipitation.
Lapse rates of 6- 8 C/km combined with the moist northwest flow
will result good orographic lift over the mountains Thursday night
through Friday night. Heaviest snowfall amounts will be favored
northwest slopes where up to a foot of snow will be possible.
However most locations will see less snow since the main forcing
will be orographic lift. Will issue a Winter Weather Advisory for
this in the mountains. Models are in good agreement with strong
winds developing behind the surface low Friday. All models point
towards at least 60 mph wind gusts for the plains with the
potential for 70 mph gusts. Will issue a High Wind Watch for much
of eastern Colorado for Friday through Saturday afternoon.
Mountain snow and high winds slowly decrease Friday night and end
Saturday morning, though very windy conditions may linger through
Saturday over eastern Colorado.
The storm system will finally move east of the area Saturday
night with ridging returning to the region for Sunday.
Temperatures will climb to near normal Sunday and above normal for
Monday while the upper level ridge moves across the Central
Rockies. Winds likely increase late Monday on the backside of the
ridge.
A quick moving system will race across the Northern Rockies
Tuesday. This may bring snow to the mountains. There will be a
better for windy conditions with the system as it passes north of
Colorado. On Wednesday, upper level ridging will return bringing
dry and mild conditions.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 810 PM MDT Wed Apr 11 2018
Surge of more northerly winds is working into northeastern
Colorado and may cause some variability in winds in the Denver
area between 03z and 06z. After that, S/W drainage winds overnight
will increase in the morning hours, with gusts to 25 knots
developing by 15z. Stronger winds in the afternoon with 30-40 knot
gusts between 18z and 24z. Direction should stay southwesterly
most of the day, but there is a chance of strong west winds for a
few hours in the late afternoon or early evening that could cause
crosswind issues at KDEN/KAPA. A shift to northwest winds is
expected by 02z Friday that would reduce the crosswind issues.
&&
.FIRE WEATHER...
Issued at 810 PM MDT Wed Apr 11 2018
Expanded the Red Flag warning for Thursday northward to include
the Larimer county foothills and the plains from Fort Collins to
Morgan county. Models are trending toward a faster flushing out
the shallow moisture layer which is moving into these areas this
evening. The models are also likely too high with the dew points
in the drier air, resulting in humidities near or a little below
15%. With 35-40 mph wind gusts expected, this is sufficient for
the warning to be expanded to these areas. While conditions across
some of these areas will only be marginal in the afternoon for a
few hours, the HRRR has the southwesterlies spreading into
southern Weld and Morgan counties with Red Flag conditions by 10
AM, and strong winds in the foothills again by that time as well.
Still expecting the most extreme conditions to be across areas
south of Denver, and possibly into the city itself in the
afternoon.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
High Wind Watch from Friday morning through Saturday afternoon
for COZ041-046>051.
Red Flag Warning from 10 AM to 9 PM MDT Thursday for COZ214>216-
238>247-249.
Winter Weather Advisory from 6 PM Thursday to 9 PM MDT Friday
for COZ031-033-034.
High Wind Watch from Friday morning through Friday evening for
COZ042>045.
&&
$$
UPDATE...Gimmestad
SHORT TERM...Bowen
LONG TERM...Meier
AVIATION...Gimmestad
FIRE WEATHER...Gimmestad
Area Forecast Discussion
National Weather Service Caribou ME
1032 PM EDT Wed Apr 11 2018
.SYNOPSIS...
An occluded front will overnight as it approaches the region
from the southwest. High pressure will build across the region
on Thursday. Low pressure will track eastward from the Great
Lakes region later Thursday and cross the region Thursday
night.
&&
.NEAR TERM /THROUGH THURSDAY/...
1030 PM Update...
Clouds overspreading the CWA late this evening per the latest IR
satl imagery. Regional radar loop showed light returns which is
mainly aloft as the llvls remain dry. This is supported by
the latest RAP & CAR soundings. Decided to pull back on the
precip chances this evening and then brought in 20% across
portions of the Crown and western areas. Otherwise, most of the
region should be precip free. Temps were also adjusted upward
given the latest obs showing readings warming than
previously forecast. Cloud cover will help to keep overnight
mins up. The rest of the forecast looks to be in line attm.
Previous Discussion...
High pressure continues to retreat this evening as the
decaying occlusion approaches. This front and associated upper
level shortwave have very little moisture, and although upper
clouds will increase overnight, precipitation amounts will
amount to no more than a few hundredths...mostly in the western
zones. Have gone with higher pops later this evening in the
western zones since the front will disintegrate as it traverses
the state. The clouds will keep lows from dropping below the mid
to upper 20s north and around 30F for Bangor. High pressure at
the surface and aloft rebuild later tonight into Thursday. Warm
air advection with this ridge will generate highs several
degrees warmer today. Between fair weather cu and increasing
high clouds later in the day, will go with partly sunny in most
zones.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
Low pressure will move northeast away from New England Friday
with a cold front behind the low becoming stationary over the
State. The cold front will becoming stationary over the region
Saturday which will result in occasionally precipitation in the
form of rain across the south and central areas with some snow
in the far north. Will use the precipitation type from thickness
tool and Snow ratio grids for this time period. Strong high
pressure will build down from the north late in the day
Saturday.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Strong high pressure will pass to the north of the region Sunday
and bring dry conditions to the far north of the area and
showers in the far south. Intensifying low pressure will
approach from the south Sunday Night and Monday and pass to the
west of the State Monday and Tuesday. Precipitation from this
system is expected to start as snow in most areas and quickly
change to rain Sunday Night. Rain is expected to continue into
the day Tuesday. Showers and Snow showers are possible
Wednesday.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
NEAR TERM: VFR until late tonight when a brief period of snow
could provide an hour or two of IFR to FVE. Otherwise, there`s a
chance of a few hours of high IFR or low MVFR cigs early
Thursday morning before VFR returns for all terminals by mid-
morning. NAM/SREF moisture fields in the boundary layer look
overdone...as often is the case.
SHORT TERM: MVFR/VFR conditions are expected on Friday and
Saturday. VFR conditions are expected Sunday. IFR conditions are
possible Monday.
&&
.MARINE...
NEAR TERM: No significant weather is expected. Winds and seas
will increase later Thursday ahead of the low pressure system.
SHORT TERM: Have used a 50/50 blend of the Nam and Gfs for
sustained winds. For Waves: A strong southerly fetch is expected
to develop across the Gulf of Maine Thursday Night with wave
heights building to 7-8 feet/8 seconds by late Thursday Night
then subside during the day Friday. An east to southeast fetch
is expected to develop across the Gulf of Maine Sunday Night and
continue into Monday with wave heights building to 6-7 feet/8
seconds. Will use the NWPS for waves.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...Hewitt
Area Forecast Discussion
National Weather Service Charleston SC
1017 PM EDT Wed Apr 11 2018
.SYNOPSIS...
High pressure will prevail through Saturday. A strong cold
front will affect the area Sunday, followed by dry high
pressure.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
The mid and upper levels are associated with a W-NW flow to the
north of an anticyclone in the Gulf of Mexico, while at the
surface and in the lower levels we find an elongated ridge from
off New England, across the local area and stretching to near
the coast of Texas. Satellite imagery continues to show
scattered to broken cirriform clouds moving through, associated
with the upper jet. But these clouds are expected to diminish
overnight as the jet lifts further to the north. While some of
the clouds will occasionally be opaque, for the most part
translucent cirrus will dominate. Thus we don`t anticipate these
clouds to have any impact on minimum temperatures now that
winds have decoupled and become calm or light in most places.
We`re forecasting lows from the mid and upper 40s most places
inland from US-17, and 50-55F closer to the coast. A couple of
spots in the Francis Marion will fall to the lower 40s.
The overall risk for fog remains low given that the SREF,
NARRE-TL and HRRR show at most only very low probabilities of
it forming. There certainly could be some ground fog across
Georgia late tonight, but enough to include mention in the
grids.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
A fairly quiet weather pattern will persist into late week as a
broad mid/upper ridge gradually builds from the south with its main
axis positioned over the western Atlantic late Thursday into Friday,
then increases amplitude and shifts further offshore in advance of a
longwave trough approaching from the west late weekend. At the sfc,
high pressure will gradually shift offshore Thursday, then remain
centered well offshore Friday and Saturday. Given the pattern, a
southeast/south wind will prevail along the western edge of deep
layer ridging and will likely contribute to warmer temps through the
weekend. In general, highs will peak into the low/mid 70s Thursday,
then mid/upper 70s near the coast to low 80s away from the coast on
Friday. Guidance hints at a few showers developing over coastal
waters Saturday and possibly reaching the coast late in day, but
despite some increasing clouds and the potential for an isolated
shower to two, temps are expected warm into the low/mid 80s away
from the immediate coast. Overnight lows will also trend warmer,
dipping into the low/mid 50s Thursday night, then upper 50s/lower
60s Friday night.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
The main feature for the long term period remains the negatively
tilted upper trough expected to shift into the eastern United
States, pushing a strong cold front through the local area
Sunday afternoon/evening. Strong southerly wind fields will
bring breezy/windy conditions to the area ahead of the front.
Model data continues to indicate the potential for severe
weather on Sunday though it`s still quite early to pin down
details. Guidance has been very consistent with the front moving
through during the afternoon hours. Latest MOS numbers now show
high temps reaching the lower 80s, which combined with 60s
dewpoints, would yield decent instability.
Dry high pressure will prevail Monday through Wednesday with
near normal temperatures rising above normal by mid-week.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Low end chance for ground fog, especially at KSAV around
daybreak Thursday. Otherwise, VFR.
Extended Aviation Outlook: Flight restrictions are expected at both
CHS and SAV terminals Sunday afternoon/evening due to showers
and/or thunderstorms associated with a passing cold front. Breezy
conditions are also expected Sunday and Monday.
&&
.MARINE...
Tonight: Surface high pressure centered to our north will
broaden out, stretching across the coast of the Carolina`s and
Georgia overnight. E to slightly SE winds will prevail around
8-12 kt across the ocean and 5-10 kt in Charleston Harbor. Seas
will generally range from 2-3 ft within 20 nm and 3-5 ft
further offshore.
Thursday through Saturday: High pressure will gradually shift
offshore and become centered over the western Atlantic late week,
setting up a persistent southerly flow over all waters into the
weekend. Weak southeast winds will prevail Thursday and Friday along
the edge of high pressure offshore with some enhanced wind speeds
along the coast due to a seabreeze each afternoon. In general, seas
of 2-4 ft on Thursday will slowly subside to 1-3 ft Friday. On
Saturday, the pressure gradient will begin to tighten between high
pressure offshore and a trough approaching from the west. Given the
setup, seas should build to 2-4 ft while south/southeast winds gust
to 15-20 kt late in the day.
Saturday Night through Monday: The approach of a deep upper trough
and strong cold front are expected to result in strong southerly
winds late Saturday night through Sunday evening. Small Craft
Advisories will likely be needed for most if not all of the waters,
including Charleston Harbor. Gusty winds will continue into Monday
behind the cold front as winds shift to westerly. Seas will steadily
subside due to reduced fetch but we could need to hang onto SCAs
through much of Monday due to wind gusts.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...
SHORT TERM...
LONG TERM...JRL
AVIATION...
MARINE...
Area Forecast Discussion
National Weather Service State College PA
1012 PM EDT Wed Apr 11 2018
.SYNOPSIS...
Above normal temperatures are expected through the weekend. A
warm front over the area tonight will lift slowly to the north
Thursday. A strong storm system will move in from the west this
weekend. Periods of heavy rain and a few thunderstorms will
occur Sunday night into Monday, until a strong cold front pushes
through. Temperatures then drop below normal for the next week.
&&
.NEAR TERM /UNTIL 8 AM THURSDAY MORNING/...
Just a hint of the showers upstream becoming less numerous.
Latest NAM, HRRR and RAP runs continue to dissipate the showers
in the next 3-6 hours. All is well.
Prev...
WAA precip continues to penetrate the central mountains from NE
OH/NW PA. The rain is reaching farther and farther to the SE,
but clearing has developed over the Laurel Highlands. A slow
creeping northward of this frontal precip is expected this
evening, but it should be dissipating as it does - without
upper support. Next shot of short wave energy rolls in along the
same track around sunrise. But, much of the overnight should be
dry, esp in the S. Temps will dip a little, but may go up a deg
or two in the NW.
&&
.SHORT TERM /8 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
Improvement is in store for later Thursday morning and afternoon
behind the next shortwave and warm front to cross/lift north of
the region between 09z and 15z. A 3-6 hour period of showers
should accompany these features, with warming to follow in the
afternoon.
The best chance for some rain showers appears to be concentrated
over Central and Northern PA during the mid morning hours of
as the front lifts towards the Hudson and Delaware Valleys.
Highs will reach the upper 50s north to the lower 70s south.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Thursday night will be quite mild. A weak cold front trailing
southwestward from the aforementioned area of low pressure will
sag into the northern tier of PA before stalling out during the
day Friday. The front will begin to sharpen up and drift slowly
north into New York Friday into Saturday.
A peak in early spring warmth is forecast Friday into Saturday
in the warm sector with max temps in the upper 60s through the
north and mid to upper 70s through the south. Some areas in
south central PA could make a run at 80F though that would be
dependent on any cloudiness and whether there is any delay on
the exiting cold air. Rain showers will remain along and north
of the frontal boundary, north and west of central PA through
Saturday.
Model guidance has some relatively minor timing differences
with the main frontal system heading into the second half of the
weekend/early next week. The increasingly amplified springtime
pattern with distinct air masses and deep moisture feed from the
Gulf ahead of an active cold front could eventually support a
risk for heavy rain and thunderstorms - most likely in the
Sunday-Monday timeframe.
GEFS mean rainfall for locations across Central PA are in the
1.75-2.25 inch range, with some ensemble members along with the
operational EC and GFS indicating the potential for around 3
inches of storm total rainfall over the 24 to 36 hour period
where training bands of heavy rain or thunderstorms occur.
The exact timing and location of the heaviest rainfall is still
a bit uncertain. The higher end rainfall amounts would bring
the threat of small stream and poor drainage flooding.
Behind this significant low pressure system, cold air will
advect behind it. Given that 850mb temps could range from -5 to
-10C. This should drop temperatures early next week to well
below normal through the first half of the week.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Expect some patchy rain overnight with MVFR and IFR conditions
overnight.
Conditions should improve Thursday afternoon as the warm fornt
lifts to the northeast of the area.
Outlook...
Fri...Slight chance of AM low cigs N Mtns.
Sat...No sig wx expected.
Sun-Mon...Potential for widespread restrictions centered on
late Sunday through Monday period in rain of varying intensity.
LLWS also appears likely with a strong southerly Low-Level wind
max (50-60 kts at 2-5 kft AGL).
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...DeVoir
LONG TERM...Lambert/Ceru
AVIATION...Martin
Area Forecast Discussion
National Weather Service Duluth MN
649 PM CDT Wed Apr 11 2018
.UPDATE...
Issued at 648 PM CDT Wed Apr 11 2018
Have already made some minor adjustments to pops, and may have to
shift them later yet as trends develop in the next few hours.
Updated aviation section below for 00Z TAF TAF issuance.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 252 PM CDT Wed Apr 11 2018
Dry and mostly sunny conditions this afternoon will give way to a
quick round of precipitation, in the form of a wintry mix, which
will begin this evening, and persist through Thursday morning. A
mid-level shortwave trough and an associated surface low pressure
system will advance eastward through the region, placing the
Northland underneath the inverted trough of the low. The lift with
this system is concentrated in a northwest to southeast band, per
the Thaler QG omega values, so tried to follow this for my POPs.
Increasing warm air and moisture advection will provide the
support for the wintry mix, which appears to be a mix of snow and
rain, possibly some freezing rain in some spots. Both the RAP and
NAM soundings suggest a loss of ice in the dendritic snow growth
layer Thursday morning, which should lead to more freezing drizzle
vs. freezing rain. Still, we are expecting some small impacts on
travel conditions for the Thursday morning commute due to snow
accumulations and light icing. Between 1 to 2" of snow
accumulation will be possible overnight over the Iron Range and
Minnesota Arrowhead regions. Overnight lows are anticipated to
dip only into the upper 20s north to the lower 30s south.
Precipitation will gradually come to an end Thursday morning as
the surface low rapidly moves off to the east. Some chances of
precipitation, mainly in the form of drizzle, will linger along
the North Shore of Lake Superior. Otherwise, skies will remain
mostly cloudy during the day Thursday. The models are progging a
very narrow band of precipitation, which may sneak into our
southern counties by late Thursday afternoon, which presumably is
caused by the low-level warm air advection ahead of the next
weather system to impact the region for Friday and through the
weekend. Confidence is high that very little will fall from this
band.
.LONG TERM...(Thursday night through Wednesday)
Issued at 252 PM CDT Wed Apr 11 2018
The long term focus is on the system due to affect the forecast area
Thursday night through Sunday night. Models are coming into a bit
better agreement, but continue to trend southward. The large closed
upper low is pulling out of the lee of the Rockies Thursday night,
then moves into southern Iowa by 00Z/7pm Sunday, before reaching
southern lower Michigan by 12Z Monday. Its companion surface low
moves across southern Nebraska Thursday night, then into the eastern
Great Lakes by 12Z/7am Monday. This continued trek southward and the
strength of the high pressure to the north, along with the much
drier air, thermal profiles, the axis of largest QPF shifting south,
and the snow to liquid ratio being lower, there will be a tight
gradient between precipitation and no precipitation. Still
anticipating some light freezing rain as a possibility Thursday
evening during the transition period between rain and snow. This
also precludes mentioning specific snow amounts for now.
There is a possibility of some lake effect snow on the backside of
this system Sunday through Monday morning along the higher terrain
of the south shore of Lake Superior. Low confidence due to the
persistent differences in the amount of cold air. Upper level and
surface ridging cover the rest of the region Monday through Tuesday.
Temps will continue to be below normal through the long term.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 648 PM CDT Wed Apr 11 2018
VFR conditions as of issuance time to give way to a band of
rain/snow mixture that will move across the terminals mainly in
the 06z-12z time range with IFR/LIFR conditions. Expect gradually
deteriorating conditions in the 02z-06z time range. IFR/MVFR
stratus to linger after the precipitation moves through, but VFR
conditions to return to all terminals in the 21z-00z time range.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 31 42 28 33 / 80 40 30 50
INL 27 41 21 37 / 90 40 0 0
BRD 33 44 32 38 / 80 20 40 60
HYR 34 46 33 37 / 90 30 60 80
ASX 31 43 28 34 / 80 40 40 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
UPDATE...LE
SHORT TERM...JTS
LONG TERM...GSF
AVIATION...LE
Area Forecast Discussion
National Weather Service Key West FL
1043 PM EDT Wed Apr 11 2018
.DISCUSSION...
.CURRENTLY...
A cold front is positioned across the southern tip of Florida, though
its satellite presentation is less than robust, with a broken
band of clouds present across the the southern Gulf of Mexico.
Scattered showers moved into the eastern Florida Straits and Upper
Keys earlier this evening, accompanying the expected northeasterly
wind surge down the Atlantic coast. Down the western spine of
Florida, dew points have dropped into the 40s and 50s. South of
the front, the island chain is experiencing dew points in the
upper 60s, with temps ranging from 72 (Upper Keys) to 79 in Cudjoe
Key.
The 00z KEY sounding revealed an atmosphere with sub- 1000 j/kg of
instability, a bit of backing in sfc-700 mb levels, and a PWAT
near 1.1 inches.
.SHORT TERM...
A significant air mass change is not expected, as current northerly
winds (which would aid any possible CAA) are expected to veer
easterly within the next several hours in response to the surface
ridge (currently in the Southeast US) shifting into the western
Atlantic by 12z. Nevertheless, have adjusted min temps slightly to
account for current readings mainly in the Upper Keys. As for
rain, the synoptic pattern leads us to believe the best chance of
rain has already passed for the island chain, and shower coverage
should be on the downtrend as dry low-level air (evident on
MIMIC) filters southward across the Keys. However, high-res models
seem to be over-reacting to possible late night nocturnal
boundary collisions... which may actually result in low level
cloud cover, but not precipitation. This scenario is also evident
in GFS and RAP fcst soundings. Long story short, we decided to
follow instinct and modestly decrease rain chances to 10 percent
for the rest of the night, but leave the 20 percent over the
warmer waters of the Florida Straits where shower coverage
continues at this time. Expect lows of 70-75 tonight.
&&
.MARINE...
A Small Craft Advisory remains in effect for the Atlantic Waters,
Offshore Gulf, and Bayside/Gulfside waters tonight. Small craft
should exercise caution in the Florida Bay tonight. An area of
high pressure will be centered near the Carolina coastline
overnight. This area of high pressure will progress eastward into
the western Atlantic Ocean Thursday. An Atlantic ridge of high
pressure will extend across the Southeastern United States
Thursday night through Saturday, before shifting southward down
the Florida peninsula Saturday night.
&&
.AVIATION...
Until 12z/12th, VFR conditions will prevail at the Key West and
Marathon terminals with mainly northeast winds of 10 to 15 knots
with gusts near 20 knots.
&&
.PRELIMINARY POINT TEMPS/POPS...
Key West 73 83 76 84 / 10 10 10 20
Marathon 75 84 76 86 / 10 10 10 20
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...Small Craft Advisory until 5 AM EDT Thursday for GMZ032>035-
042>044-052>055-072>075.
&&
$$
Public/Marine/Fire...MCLOVIN
Aviation/Nowcasts....APA
Data Collection......DR
Visit us on the web at weather.gov/key
Follow us on Facebook and Twitter at:
www.facebook.com/nwskeywest
www.twitter.com/nwskeywest
Area Forecast Discussion
National Weather Service Marquette MI
715 PM EDT Wed Apr 11 2018
.SHORT TERM...(This evening through Thursday)
Issued at 412 PM EDT WED APR 11 2018
WV imagery and RAP analysis indicated nearly zonal mid/upper level
flow through the nrn CONUS to the south of a deep low over Hudson
Bay. Upstream shortwaves were located over Montana and the wrn
Dakotas. At the surface, ridging over the nrn Great Lakes has
brought sunny skies to Upper Michigan while erly winds were
increasing over the Upper MS valley ahead of a trough from srn
Alberta to sw South Dakota.
Tonight into Thursday, the combination of the nrn plains shortwaves,
and left exit of a 250-300 jet pushing into nrn MN/WI will provide
support for an expanding area of pcpn late tonight. Although the
stronger 285k-290k isentropic lift and 850-600 mb fgen will remain
slightly south of Upper Michigan near the 850 mb front, models
suggest that there will still be a large area of pcpn spreading to
the northeast from nrn WI btwn 06z-12z which will linger into the
ern half of Upper Michigan through 15z.
With 3-4g/kg during the brief period of stronger lift, snowfall
amounts at or slightly below the 1 to 3 inch range are expected. A
brief period of fzra/fzdz or sleet may be possible at the onset
before evaporational cooling drops wet-bulb zero temps. Lingering
warm air over the far south near MNM will keep the pcpn as mainly
rain.
Relatively mild air will linger after the pcpn ends as even under
mostly cloudy skies, highs climb to around 40 north to the mid 40s
south.
.LONG TERM...(Thursday night through Wednesday)
Issued at 316 PM EDT WED APR 11 2018
No changes in the overall complicated forecast scenario, especially
Fri and Fri night. One bright spot is, at least for now, longer
range models and ensembles have come into decent agreement in
showing relative lull over area on Sat and Sat night with widespread
precipitation returning to especially central and eastern Upper
Michigan Sun into Mon morning as primary upper level trough and sfc
low 995-1000mb lift across central Great Lakes. The initial precip
on Fri and the second round of precip could result in high impact
winter conditions in terms of heavy snow and strong winds/blowing
snow. Be sure to keep checking in with latest forecasts for up to
date details.
First for the Fri/Fri night system. Main driver of precip, mainly in
the form of snow, will be from warm air advection to north of sfc
low and sharp warm front from northern IA/southern MN into southern
WI. Temps Fri aftn will range from the lower 30s over Upper Michigan
to upper 60s in Chicago and Detroit. Frontal lifting zone will be
sloped to the north well into colder air with cross sections
indicating max ascent along the H8-H6 frontogenesis ribbon within
right entrance region of upper level jet from northern Ontario to
Quebec. Moisture inflow into the fgen band is decent with H7 mixing
ratios 3-4g/kg (equates to 6-8 inches of snow/12 hours) and pwats of
at least 0.75 inch into southern forecast area. Wherever the ascent
occurs it will be enhanced by negative epv atop the fgen which will
result in better potential for heavy bands of snow. Decending
portion of the fgen band will occur somewhere over northern Upper
Michigan to Lk Superior. The downward motion and drawing in of very
dry H85-H7 RH values below 10 pct over Lk Superior will lead to
sharp northern edge to heavier snow. Where that transition zone sets
up is really tough to pin down. Seems there is good agreement that
Keweenaw misses out on this event and southern U.P. from Iron River
to Escanaba southward would have best shot at seeing heavy snow.
Whether this heavy snow potential expands as far north and east as
Marquette, Munising or Newberry is still unclear. Latest NAM and GFS
indicate some potential for that but they are also on the northern
edge of where SREF/GEFS ensembles point to heavier snow occurring.
Based on elevated warm layer aloft at H7 could also be sleet,
especially over far south central. Soundings for scntrl also
indicate there could be a near sfc warm layer so could be dealing
with more of a mix and less snow. Finally, if snow is bigger ptype
into Fri night over the scntrl, could be looking at blowing/drifting
snow along Bay of Green Bay with east winds gusting over 30 mph
possible off the still frozen waters of the Bay of Green Bay. After
coordination with WPC and surrounding offices at APX/GRB and DLH,
will opt to not issue winter storm watch right now and continue to
mention hazard in SPS, HWO and on social media. Also plan to send
out DSS briefing package for core partners on Thu.
Looks like the Fri/Fri night system exits south central Upper
Michigan early Sat morning. For rest of Sat, building high pressure
and dry air should shut down most of the snow chances on into Sat
evening. One exception could be far scntrl with shortwave working
across and that area seeing some mid-level frontogenesis in right
entrance of region of upper level jet arcing from U.P. toward
Quebec. Possible that if this expected forcing sets up, light to
maybe moderate snow could occur far scntrl Sat into Sat evening.
Away from this area though, appears conditions will be generally
quiet most of Sat.
Then, as upper trough over the Plains edges toward western Great
Lakes and sfc low heads into the Ohio Valley late Sat night, expect
another surge of moderate to heavy precip, mainly in the form of
snow, to begin lifting into the Upper Great Lakes. Right now it
appears the heaviest snow would occur from Sun morning through Sun
evening. Moderate snow could persist into Mon morning over north
central with convergent northerly sfc-h85 winds. Given the deep
moist cyclonic flow and H85 temps down to -11c or -12c (ECMWF even
shows -15) over Lk Superior there would also be enhancement to snow
over north central Upper Michigan due to lake enhancement (depending
on extent of ice cover/fluxes) and upslope lift. Total qpf from Sun
morning through Sun night from latest models and ensembles, which
agree pretty well, checks in around 0.5 inch except far west cwa
with decent chance of seeing 0.75 inch for eastern forecast area
into eastern Upper Michigan. Stronger deformation on cyclonic side
of H85 low and mesoscale enhanecements already mentioned could push
total qpf over an inch east half. SLRs of 10:1 to 15:1 with this
expected qpf could lead to over a foot of snow over north central
and eastern forecast area. In addition, blowing/drifting snow late
Sun night into Mon morning could be issue with expected wind gusts
of 20 to 30 mph. Will start to message this time frame in
SPS and HWO for possible higher impacts.
Beyond the Sun into Mon morning system, looks to stay cold for most
of next week as upper level troughing lingers. Could also be some
light snow or flurries at times. In other words, no spring warmup is
expected through most of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 710 PM EDT WED APR 11 2018
VFR conditions are expected across all TAF sites into this evening.
A low pressure system will approach tonight, leading to MVFR and
eventually a period of IFR/LIFR conditions late tonight into
Thursday morning as light to moderate snow moves into the area.
Expect improvement to MVFR and possibly VFR Thu afternoon as snow
dissipates.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 412 PM EDT WED APR 11 2018
Light winds are expected tonight into Thursday. As a strong low
pressure system slides through the area Friday through the weekend,
winds will increase across the area with gales up to 40 knots
possible through Saturday night.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...Voss
MARINE...JLB
Area Forecast Discussion
National Weather Service San Francisco Bay Area
509 PM PDT Wed Apr 11 2018
.SYNOPSIS...A frontal system will bring light rain to the North
Bay late this afternoon. Rain will spread south and east
Wednesday evening. Dry conditions and warming temperatures are
likely Friday into Saturday with another cool down and chance of
precipitation Sunday into early next week.
&&
.DISCUSSION...as of 1:37 PM PDT Wednesday...Weather headline
through the next seven days is active weather pattern remains in
place.
Latest surface analysis puts a cold front just off the northern
coast of California. The latest KBHX radar indicates an intense
narrow cold frontal rain boundary making its way to the coast.
This cold front has slow a tad from previous forecasts leading to
a later start time of rain in the North Bay. An earlier update to
the forecast was made to address the slower timing. The latest
HRRR models bring rain into the North Bay closer to 22-00Z and the
heart of the Bay Area toward the tail end of the evening commute.
This frontal boundary then continues south and east tonight
bringing rain chances all the way south to Monterey/San Benito. A
few showers may lingering early Thursday then gradual drying.
Rainfall amounts will generally be a few hundredths to a few
tenths. Highest rainfall amount will be North Bay and coastal
mountains. Haven`t see any lightning strikes yet, but there is a
very small chance for convection later today over the North Bay.
Conf is low and will not include in the official forecast, but
something to mention. Snow levels will drop 3-4k feet.
Mostly dry conditions on Thursday, but it will remain cool in the
post frontal set up. High pressure builds Friday and Saturday
leading to a nice warm up with highs in the 60s and 70s, which is
close to climo for this time of year.
Ridge of high pressure begins to flatten and shift eastward
Saturday into Sunday as the next system takes aim at NorCal. Rain
chances return during the day Sunday as a cold front moves through
from NW to SE. Showers remain on Monday as the upper trough swings
through. This system will colder as well with lower snow levels to
3-4k ft.
A brief break on Tuesday and Wednesday with a little warm up, but
long range models show another system moving in from the NW
bringing yet another chance of precip to the region late next
week.
It`s common during the spring months to get these fast moving,
quick hitting storm system. None of them appear to be major precip
producers.
&&
.AVIATION...As of 5:08 PM PDT Wednesday...For 00z Thursday tafs.
A cold front, currently entering the North Bay, will be passing
through KSTS in the next hour or two. As of 2345z, surface
observations show VFR at all terminals. Expect cigs to lower
around or below 3000 ft briefly along the front. In addition,
expect light to moderate rain along the cold front, with isolated
showers behind the front. The front is expected to pass through
the SF Bay Area between 02-04z, then the Monterey Bay Area between
04-06z. Gusty SW winds will turn W/NW once the front passes,
remaining gusty overnight.
Vicinity of KSFO...Borderline MVFR/VFR cigs along the cold front
(arriving by 02-03z). Cigs will quickly lift and scatter out
behind the cold front, by 05z or so. Light to occasionally
moderate rain will cause wet runways starting around 02z through
about 05z. Winds will be gusty behind the front, gusting in excess
of 30 kt into the early morning hours of Thursday. Winds are
forecast to decrease slightly by mid morning Thursday before
increasing again and becoming gusty Thursday afternoon.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR ahead of cold front, then borderline
MVFR cigs after 03Z THU. Generally light rain with a few brief
periods of moderate rain will cause wet runways 03-07Z THU.
Breezy, occasionally gusty, onshore winds thru TAF.
&&
.MARINE...as of 04:34 PM PDT Wednesday...Gusty southwest winds
today ahead of a passing cold front. Winds will veer northwest but
remain gusty in the wake of the frontal passage. In addition to
the winds, hazardous seas will develop due to steep fresh swell
across the coastal waters. Winds will back off but remain breezy
to locally gusty through tomorrow.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pt Reyes to Pigeon Pt 0-10 nm
SCA...Pigeon Pt to Pt Pinos 0-10 nm
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
SCA...Rough Bar Advisory for SF Bar from 9 PM
SCA...SF Bay
SCA...Mry Bay
&&
$$
PUBLIC FORECAST: MM
AVIATION: BAM
MARINE: DRP
Visit us at www.weather.gov/sanfrancisco
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayarea
Area Forecast Discussion
National Weather Service Portland OR
236 PM PDT Wed Apr 11 2018
.SYNOPSIS...Rain and mountain snow will dominate the weather through
at least the weekend. A cold front will move across the area this
afternoon and evening with cool showers tonight and Thursday. A warm
front will produce additional rain and mountain snow on Friday
followed by a by another cold front Saturday night and Sunday.
Another warm front is expected early next week.
&&
.SHORT TERM...Today through Saturday night. The cold front is moving
inland slowly, and is over the coast range early this afternoon.
weather stations along the coast measured 0.15 to 0.35 inch in the
past 6 hours. The rain on radar imagery is looking less organized
over SW Washington and NW Oregon than it was this morning, but still
expect a few hours of steady precipitation near the front as it moves
inland. There will be a few hour delay though inland due to the slow
moving nature of this front. THe HRRR model which is initialized
from radar data forecasts the front will be over the Willamette
Valley 4-5 PM PDT and over the Cascades around 7 PM.
An upper level trough will support showers behind the front tonight
and Thursday. THe trough takes on a slight negative tilt as it
reaches the Pacific NW this evening, and there may be an isolated
thunderstorm or two offshore and along the immediate coast. The
showers may be heavier at times during this period, and possibly
contain small hail. The best timing for this is between 3 and 10 PM
tonight. Cooler air moves in with this trough and the snow levels
will lower down to around 2500 feet late tonight through Thursday
morning. This will provide the opportunity for the higher elevations
of the coastal mountains and the Cascade foothills to get a couple of
inches of accumulating snow. This is also the best chance for the
Cascade snow amounts to verify the Winter Weather Advisory. THe
showers may intensify or become more frequent early Thursday morning
when a short wave trough moves over the area.
Showers will decrease Thursday afternoon and evening, but not stop
all together. Then a warm front will produce light steady rain
Thursday night through Friday morning. Snow levels will rise with the
warm front up to around 4000 feet Friday afternoon, then above 5000
feet Friday evening. The cold front will be slow to arrive, and there
may be a dry period Friday night through Saturday morning. THe cold
front will then slowly move inland Saturday afternoon and night or
possibly not until Sunday. ~TJ
.LONG TERM...Sunday through Wednesday. A broad upper level trough
will support cool unstable weather Sunday and Monday with snow levels
lowering down to around 3000 feet. A warm front will continue rain
Tuesday. Upper ridging should keep the parent low and trailing cold
front offshore Wednesday for a mostly dry day with slight warming.
~TJ
&&
.AVIATION...The front has finally arrived at the coast alone with
MVFR conditions and rain. Expect these conditions to slowly push
inland through this evening. An unstable and showery environment
behind the front should lead to predominantly VFR conditions
returning tonight with only intermittent MVFR conditions
expected from behind the front through the day Thursday.
KPDX AND APPROACHES...May still see some MVFR conditions late
this afternoon and into the evening as a front very slowly moves
through the area. An unstable and showery environment behind the
front should lead to predominantly VFR conditions with hard to
predict and generally short lived bouts of MVFR conditions
tonight through at least Thursday morning. Bowen/Neuman
&&
.MARINE...Winds have dropped off as the front has finally passed
through the waters. Seas, however, continue to be in the 12 to
14 ft range. With decreased winds, expect seas to drop some
tonight, but likely stay above 10 ft.
Several weaker fronts will bring bouts of Small Craft Advisory
level wind gusts of 25 to 30 kt across the waters Thursday
through Sunday. A large westerly swell still appears on track to
push seas as high as the upper teens late Thursday afternoon and
early evening. There appears to be a decent chance quieter
weather will return to the waters early to mid next week.
Bowen/Neuman
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 7 PM PDT Thursday for Cascades in
Lane County-Northern Oregon Cascades.
WA...Winter Weather Advisory until 7 PM PDT Thursday for South
Washington Cascades.
PZ...Small Craft Advisory for winds from 2 AM Thursday to 5 AM PDT
Friday for Coastal Waters from Cape Shoalwater WA to
Florence OR out 60 NM.
Small Craft Advisory for hazardous seas until 11 AM PDT Friday
for Coastal Waters from Cape Shoalwater WA to Florence OR
out 60 NM.
Small Craft Advisory for Rough Columbia River Bar until 6 AM
PDT Thursday.
&&
$$
Interact with us via social media:
www.facebook.com/NWSPortland
www.twitter.com/NWSPortland
This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. This area is
commonly referred to as the CWA or forecast area.