Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/16/18
AREA FORECAST DISCUSSION
National Weather Service Albany NY
942 PM EST Sat Dec 15 2018
.SYNOPSIS...
High pressure builds in tonight from southern Quebec
with colder temperatures. A complex storm system will approach from
the Mid Atlantic Region towards daybreak bringing a wintry mix of
precipitation to eastern New York and western New England. The storm
system will move northeast toward Cape Cod Sunday night
transitioning all the mixed precipitation to snow. A strong cold
front will move through on Monday with isolated to scattered snow
showers and possibly a few snow squalls.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Winter Weather Advisory begins at 4 AM for Dutchess and Ulster
Counties in NY, and Litchfield County in CT and runs until 4 AM
Monday...
As of 942 PM EST...Slowed onset timing of precip for southern
areas slightly based on obs and trends from 00Z HRRR and 3km
NAM. Drier air in low to mid levels continues to push southward
this evening as high pressure advances eastward through SE
Quebec. 00Z KALY sounding indicated a significant dry layer from
near the surface up to around 600 mb. Surface dewpoints have
dropped into the 20s from around the Capital District northward
already. So it will take slightly more time for precip to
advance northward and reach the ground. The advisory start time
still looks good for southern zones, as precip onset looks to
occur around 5-7 AM.
Coldest temps tonight will be over the northern most zones
(southern Dacks, Lake George Region, and southern VT), which
will drop off sharply into the teens and lower 20s by early
Sunday morning. From the Mohawk Valley and Capital Region,
Berkshires south, clouds will gradually increase, thicken and
lower, but with low-level cold air draining southward we are
expecting lows in the 20s to around 30F.
Attention shifts towards the complex storm system over the TN
Valley on the water vapor loop. The H500 cut-off will lift
slowly to the northeast with a sfc cyclone forming near the Mid
Atlantic States. Low and mid level warm advection with the
complex system will allow for some mixed pcpn to break out after
midnight over the southern most zones of Ulster, Dutchess and
Litchfield Counties. It looks like this will occur between 5-7
am, as the isentropic lift increases, and a strengthening low-
level east/southeast jet impacts the region. We leaned closer to
the colder NAM guidance and factored in the 12Z HREFs which
support a rain/freezing rain or freezing rain/sleet onset, as
wet bulb cooling occurs. The critical partial thicknesses and
thermal profiles supported the mixed pcpn scenario from the
GFS/EC and some GEFS too.
We used the colder NAM thermal profiles for the forecast, and
the depth of the subfreezing air will determine the ptype,
which continues to be challenging and low confidence at this
point. Based on collab with the neighboring offices (WFO BOX,
OKX, and BGM), the threat of freezing rain with H850 temps of
+3C to +5C over these area with the subfreezing temps at the sfc
we started the winter weather advisory at 4 am.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
Winter Weather Advisory continues for Dutchess, Ulster and
Litchfield Counties to 4 am Monday...
Winter Weather Advisory for northern Catskills, Greater Capital
Region, Taconics, Helderbergs, Schoharie Valley, Mohawk Valley
and Berkshires from 7 am Sunday to 4 am Monday...
Winter Weather Advisory from noon Sunday to midnight for
southern VT, northern Saratoga, southern Washington, and
southeast Warren Counties...
Tomorrow...This remains a low confidence forecast, as we enter
the short term with the northward extent of the QPF and the
thermal profiles varying on the short range guidance continue to
vary. If the thermal profiles end up colder, as the last few
runs of NAM are alluding too, then this could before more snow
than mixed pcpn of sleet, and freezing rain (albeit light for
most of the area), but still having a societal impact on the
roads, etc.
Low pressure continues to deepen as it moves towards the
Delmarva Region by the late morning into the afternoon. The
easterly winds in the H850 to H700 layer may downslope off the
western New England higher terrain limiting the northward
progress of the pcpn across the forecast are especially from the
Capital Region north early on. For example, the 12Z NAM, and
the 12Z EC have shown this possibility. However, as the upward
vertical motion increases with the isentropic lift on the
285/290K sfcs with upper level diffluence over the region, the
pcpn should fill in and spread north. The model soundings, and
critical partial thicknesses support more snow with a little
sleet potentially over the northern most zones. We have left the
southern Adirondacks out with perhaps an inch or two of snow or
sleet. Southern VT could get a mixture of snow and sleet with
some freezing rain, as wet bulb processes occur. Further south
into the Capital Region/Mohawk Valley/Berkshires wet bulb
cooling and better synoptic lift may promote sleet, snow and
freezing rain in the late morning into the afternoon. The pcpn
may transition to a period of rain especially in the valley
areas or below 500 ft in elevation. This will occur if the pcpn
lightens in intensity or if enough warming occurs between surges
of moisture. We leaned closer to the METMOS colder temps for
more wintry mix pcpn types during the day. Highs will be in the
upper 20s to lower 30s over the mtns, and mainly mid 30s in most
other locations. Total snow/sleet may be a few tenths of an
inch to an inch or two especially over the higher terrain. Ice
accretions may be in the coating to tenth of an inch range. We
issued the advisories for the freezing rain threat, but snow
totals may have to be increased if the thermal profiles trend
colder, which the 18Z NAM has trended too from roughly the
Capital Region north and west by the afternoon.
Sunday night...The GFS is definitely the wetter guidance in
terms of the QPF heading into Sunday night over the Litchfield
Hills/Mid Hudson Valley with 1-1.5+ inches, where the NAM, EC
and WPC/NERFC QPF is much lower by almost half. As the system
deepens and intensifies south and east of Long Island and moves
towards the benchmark of 40N/70W, colder air gets drawn towards
the system quickly, which should transition rain/sleet/freezing
rain to all snow fairly quickly. We may need to increase snow
totals across the Berkshires/Litchfield Hills/central and
southern Taconics if this occurs (also decent QG lift may occur
with good pcpn efficiency in the dendritic growth zone of -12C
to -18C). For now, we have 1 to 3 inches and have kept the
advisories going to 4 am especially for these areas. The snow
may end across southern VT around midnight, if it lingers then
the advisory may have to be extended. Overall, expecting the
pcpn in the form of snow/snow showers to end quickly in the
deformation zones of the system between 4-7 am. Lows fall back
into the 20s.
Monday-Monday night...A strong northern stream short-wave trough
approaches and follows in the heels of the southern stream
complex low pressure system. Some scattered rain/snow showers
are possible with the short-wave trough and associated cold
front. The better chance for a few snow squalls will be
northwest of the Capital Region where steeper lapse rates,
colder temps, and moisture profiles line up. The greatest threat
would be in the afternoon. Highs get into the upper 30s to lower
40s in the Hudson River Valley and NW CT. Temps will be in the
upper 20s to mid 30s in most other locations. The winds will
increase from the west to northwest at 10-20 mph late in the day
with gusts 30-40 mph. Snow amounts will vary from a coating to
an inch in the heavier snow showers/squalls.
A brief lake connection occurs Monday night in the strong cold
advection as the flow veers to the northwest. Some upslope snow
showers are possible for the north-central Taconics and southern
Greens too. Snow amounts could range from a half an inch to a
few inches. Blustery and cold conditions will prevail with wind
chills in the 10 below to teens across the region with actual
air temps in the teens and lower 20s with a few single numbers
of the southern Adirondacks.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
The period starts out on Tuesday with a deep upper trough over
New England, but will shift east into the Canadian Maritimes
through the day. With ridging upstream over the upper Great
Lakes, there will continue to be a fairly strong northwest flow
resulting in cold and brisk conditions with gusts winds. Temps
will be below normal Tuesday through Tuesday night, although
winds will diminish Tuesday night as a surface ridge moves over
the region.
After a cold start, temps should moderate back to near normal
levels on Wednesday as the ridge shifts SE of the area and a
light southwest flow develops. Dry conditions will persist
Wednesday night into Thursday, as upper level heights rise in
response to a developing storm system over the Gulf coast
states.
On Thursday, the upper level pattern is forecast to become
highly amplified, with a deep trough and closed low forming over
the Tennessee valley region, with ridging along the east coast.
This pattern will induce a southerly flow starting Thursday,
but will really strengthen Thursday night into Friday. So valley
areas from around the Capital District southward could exceed
40 degrees on Thursday, with little if any cooling Thursday
night as S/SE flow increases. Most areas should reach at least
the mid 30s.
As the storm system deepens and moves northward through the
Ohio Valley Thursday night into Friday morning, it will spread
widespread precip into our area. Due to some low-level cold air
trapped in the typical sheltered/high elevation valleys of the
western/southern Adirondacks and southern Green mountains, there
could be some freezing rain at the onset. Otherwise, it appears
a soaking rain will occur for most of the area with warm
thermal profiles seen both in the GFS/ECMWF with 850 mb temps
around +4C or greater. With the strengthening wind field, there
could be some hazardous wind gusts across the usual areas
favored in SE flow, such as the Taconics, southern Greens, and
Berkshires. Will need to monitor trends with wind as the event
draws near. Trends in QPF will also be monitored for potential
hydro issues.
Steady precip should end by late Friday, as a dry sector moves
in behind the system`s occluded front. Potential for strong
winds should also diminish by then as the low level jet shifts
well eastward into New England. As the system`s upper trough
settles in Friday night into Saturday, cold advection will
occur. Some lake enhanced/upslope rain/snow showers are
expected, with the higher terrain seeing any rain showers change
to snow first.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Tranquil flying conditions occurring this evening, with just
increasing high level clouds, as high pressure builds in
tonight from southern Quebec. However, a complex storm system
will then approach from the mid Atlantic region towards Sunday
morning, bringing a wintry mix of precipitation to the region.
A mix of freezing rain, sleet and possibly even some snow will
develop from south to north across the terminals Sunday morning,
first at KPOU around 09Z, KPSF by around 15Z, KALB by around 17Z
and KGFL by around 18Z. There is still some uncertainty with
regards to both onset time and precip types, although some sort
of wintry mix does appear likely. Conditions will lower from VFR
to IFR within a few hours of precip onset. KPOU may should see a
changeover to rain during the afternoon, while the other
terminals are expected to experience a wintry mix continuing.
Winds will be northerly around 4-8 kt, becoming northeast around
5-10 kt by later Sunday morning.
Outlook...
Sunday Night: High Operational Impact. Likely SN.
Monday: Moderate Operational Impact. Breezy Chance of SHRA...SHSN.
Monday Night: Moderate Operational Impact. Windy NO SIG WX.
Tuesday: Low Operational Impact. Breezy NO SIG WX.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: Low Operational Impact. Slight Chance of RA.
&&
.HYDROLOGY...
No major hydro problems are expected into the mid week.
Dry weather is expected into early tonight before some light
mixed pcpn moves into the southern extreme of the Hydro Service
Area by daybreak. The mixed pcpn will expand across the region
on Sunday before transitioning back to snow Sunday night with
light accumulations of ice and snow expected. Total QPF for this
event will range from a tenth of an inch of less over the
northern portion of the HSA with a half to three quarters of an
inch over the Mid Hudson Valley, southeast Catskills and
Litchfield Hills. Some localized one inch amounts are possible
in the Housatonic Basin. Some within bank rises are possible on
the main stem rivers due to some rain, mixed pcpn and snow
melt, but flooding is not expected at this time (caution stage
for Poughkeepsie due to the east/southeast flow and the tidal
impact and for Stevenson Dam which is regulated).
A strong cold front moves through on Monday with much colder
air moving into the region for Tuesday, as flows will continue
to lower during the early to middle portion of next week with
some ice formation and build up possible on the waterways.
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...Winter Weather Advisory from 4 AM Sunday to 4 AM EST Monday
for CTZ001-013.
NY...Winter Weather Advisory from 7 AM Sunday to 4 AM EST Monday
for NYZ038>040-047>054-058>061-082.
Winter Weather Advisory from 4 AM Sunday to 4 AM EST Monday
for NYZ063>066.
Winter Weather Advisory from noon Sunday to midnight EST
Sunday night for NYZ041-083-084.
MA...Winter Weather Advisory from 7 AM Sunday to 4 AM EST Monday
for MAZ001-025.
VT...Winter Weather Advisory from noon Sunday to midnight EST
Sunday night for VTZ013>015.
&&
$$
SYNOPSIS...Wasula
NEAR TERM...JPV/Wasula
SHORT TERM...Wasula
LONG TERM...JPV
AVIATION...JPV
HYDROLOGY...BGM/Wasula
AREA FORECAST DISCUSSION
National Weather Service Burlington VT
938 PM EST Sat Dec 15 2018
.SYNOPSIS...
Quiet weather will continue through tonight ahead of an approaching
system. On Sunday, a snow and sleet mix will move into southern
Vermont just before noon with snow overspreading much of Vermont and
northern New York during the afternoon. Accumulations will generally
be an inch or less with the main focus across southern Vermont. Snow
showers associated with the passage of the upper level trough will
be seen on Monday with upslope locations and higher terrain likely
to see an inch or two while most locations see less than an inch.
These showers will taper off heading into Tuesday with high pressure
building into the region. Drier and near normal temperatures will be
seen for the second half of the work week with the next storm system
to move into the region on Friday.
&&
.NEAR TERM /THROUGH SUNDAY NIGHT/...
As of 927 PM EST Saturday...Temps continue to stay above
expected values due to the combination of clouds and some bl
mixing. Have increased hourlies to match obs and bumped
overnight lows by 1 to 3 degrees. Expecting lows upper teens to
upper 20s. Whiteface is currently 34f, which is supported by RAP
850mb over the dacks of 1 to 2C, while Mansfield is 25 with
cooler low level thermal profiles, damming against the Greens
from sfc high pres to the north.
Based on 00z HRRR, 00z NAM12km and 4km have bumped pops to
likely across central/eastern VT, with cat pops over
Rutland/Windsor counties on Sunday aftn/evening. Also have
increased qpf and associated snowfall by several inches,
especially favorable southeast upslope regions near
Ludlow/Killington toward Mt Allen/Camels Hump. Thinking dusting
to 2 inches valleys below 1000 feet with 2 to 4 inches possible
above 1000 feet. As precip rotates into the very dry airmass
across our cwa, wet bulb cooling will occur to support mostly
snow. Some rain and snow mix is possible in the cpv away from
the heavier precip rates and immediate ct river valley areas.
Forecast challenge continues to be how much moisture/lift
rotates from sfc low pres tracking along the coast into a deep
dry layer over central/northern New England. Expect some precip
to evaporate, given the depth of dry air in place, especially
near the international border, with a sharp south to north
precip gradient.
Previous discussion below:
Filtered sunshine behind a weak frontal passage has allowed for
temperatures to rebound nicely this afternoon. Don`t get too
attached to the filtered sunshine as a thick blanket of cloud
cover residing to our south has already begun to march
northward. Through the remainder of the afternoon and evening,
temperatures will be pretty slow to fall with a mix of low and
high clouds helping to insulate the surface with temps bottoming
out in the mid teens to mid 20s. While the weather remains
quiet overnight for the North Country, a stacked low pressure
system will steadily move across the Ohio and Tennessee Valleys.
Heading into Sunday morning, precipitation chances begin to
increase as Atlantic moisture couples with lift associated with
the low as it tracks across the Mid Atlantic.
A mix of sleet and snow will move into Rutland and Windsor counties
just prior to noon on Sunday. Precipitation type has been very
tricky as subtle changes in the low track determine how quickly
colder air moves in from the north or how far north a warm nose
around 850 mb moves in. Based on the 12Z guidance, thermal profiles
support an hour or so of mixed snow and sleet across southern
Vermont but given the low current low track, the warm nose will
likely reside over central and southern New York. This should allow
the atmosphere to wet-bulb (adiabatically cool) during the early
afternoon across southern Vermont and precipitation will quickly
change over to snow. This snow will then spread northward across
Vermont and northern New York throughout the day. Snowfall
accumulations will generally be less than an inch but up to two
inches will be possible across upslope regions of the Green
Mountains. Snow chances will taper off Sunday night with a push of
drier air ahead of the main trough passage on Monday.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
As of 332 PM EST Saturday...Increasing precipitation chances on
Monday as a digging shortwave rotates across the region. The day
will likely start out fairly dry as moisture will be limited, but
precipitation will become more widespread during the afternoon and
evening as moisture increases and best dynamics swing across the
area. Temperatures will be in the lower to mid 30s, so anticipate
mainly snow through the daylight hours, though it may be warm enough
in the wider valleys for a period of rain in the afternoon. The
shortwave shifts to our east Monday night, with the deepening slow
moving just south and east of Nova Scotia. This will result in winds
turning to the northwest, focusing the snow on the favored upslopes
of the northern Adirondacks and Greens, but then gradually waning as
we head into Tuesday morning. Snow accumulations will be 1 to 3
inches with the highest numbers in those favored upslope regions.
The other concern for Monday night will be gusty winds, as the
pressure gradient tightens between the aforementioned Nova Scotia
low and high pressure approaching from the west. Gusts of 30 to 35
mph will be possible. Lingering snow showers will continue to wane
in coverage Tuesday, with Tuesday afternoon likely dry. We may see a
bit of sunshine in the afternoon as well, but continuing cold
advection on northwest winds will make it a chilly day. Highs will
be in the teens and 20s.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 332 PM EST Saturday...High pressure will settle across the
region during the middle of next week, bringing a stint of dry and
cold weather. However, things change significantly as we head into
the latter half of the week as a high amplitude trough digs into the
Southern Plains. This will spread a deep plume of moisture northward
from the Gulf of Mexico into the Northeast, while low pressure lifts
north west of the Appalachians into the eastern Great Lakes.
Precipitation will move in late Thursday/Thursday night, likely
starting out as snow, but warming temperatures will change it over
to rain on Friday, perhaps with a period of wintry mix during the
transition. Precip will continue into Saturday, likely changing back
over to snow as the low moves to our east and winds turn to the
northwest. The other concern with this system will be potentially
gusty south to southeast winds, potentially in the favored downslope
areas in the Greens. This system is still a ways out, so we will
continue to monitor for any changes in the model trends.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Through 00Z Monday...Widespread VFR conditions will prevail
through the TAF forecast period. Only exception to this will be
KRUT, which will see ceilings lower to MVFR and reduced
visibilities after 21Z as some light moves through. Otherwise,
high clouds currently streaming over the forecast area ahead of
low pressure well to our south will thicken and lower generally
to 5k to 8k ft after 18Z as the system moves off the Mid-Atlantic
Coast. Winds will be light (under 5 kts) and variable through
the TAF package.
Outlook...
Sunday Night: Mainly VFR, with areas MVFR possible. Chance SN,
Slight chance SHSN.
Monday: MVFR. Chance SHSN, Chance SHRA.
Monday Night: Mainly VFR, with areas MVFR possible. Chance SHSN.
Tuesday: Mainly VFR, with local MVFR possible. Slight chance
SHSN.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. NO SIG WX.
Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. Slight chance RA, Slight chance SN.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Clay
NEAR TERM...Clay/Taber
SHORT TERM...Hastings
LONG TERM...Hastings
AVIATION...RSD
Area Forecast Discussion
National Weather Service Caribou ME
928 PM EST Sat Dec 15 2018
.SYNOPSIS...
High pressure will into the region later tonight and then move
to the east on Sunday. Low pressure is expected to move across
the outer waters of the Gulf of Maine on Monday.
&&
.NEAR TERM /THROUGH SUNDAY/...
9:28 pm update: Satellite pictures and observations as of 9 pm
indicate a mainly clear sky across the FA with just a few
patches of stratus is parts of the Saint John Valley and
northern Somerset County. The 00z KCAR sounding shows a moist
layer around 850H, and model soundings indicate low level
moisture gets trapped under an inversion and should lead to more
widespread stratus very late tonight into Sun morning across
the north. Made some adjustments, mainly to lower the cloud
cover a bit in the north over the next few hours. Otherwise,
only minor tweaks based on the latest observations and trends.
Previous discussion:
Temperatures for this term will be above normal for mid
December. Quite a change from this past week.
An upper trof is forecast to swing across the region this
evening w/weak caa. Satl imagery showed some cloudiness hanging
on across the region but showing some breaks in the clouds. NW
flow taking hold this evening will help to dry things out early
tonight w/skies clearing across the central and southern parts
of the CWA. Across the n and w, expecting some partial
clearing, but clouds look like they could set up overnight into
the early morning hrs on Sunday as llvl gets trapped under an
inversion. The 12Z NAM and RAP soundings support this setup and
the GFS is close to this as well. Therefore, decided to lean
w/some more clouds arriving across the northern 1/2 of the CWA
later tonight. Another item to be aware of is the potential for
some fog development tonight w/the initial clearing and
cooldown, as temps were able to warm today into the 30s. The
decision was to go w/some freezing fog after midnight. Patchy
black ice could also be a concern.
For Sunday, high pres is expected to ridge across the state
during the day and then slide to the east by the
afternoon. Leaned away from the model guidance and went a tad
warmer given a good deal of sunshine in the forecast and
w/light winds. Therefore, looking for temps to warm into the
30s across the entire region w/the exception of far northern
Maine as readings could stay just under 30F.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
12Z model guidance in pretty good agreement with regard to the
developing mid-atlantic system. The model consensus takes the
low to the east of Cape Cod by late Sunday night and then
northeast across the eastern tip of Nova Scotia by Monday
evening. This track is too far east to be a major snow producer
for northern and downeast Maine. However, some accumulating snow
is still expected as an approaching upper trof from central
Canada interacts with the eastward moving coastal low. Ptype
with this system is mainly snow, as coastal low remains well to
our and south and east. The only exception will be across
portions of interior downeast Maine where enough maritime air
may get wrapped westward for a bit of a mix early Monday.
Although the low will continue to move well east of the region
by Monday evening, some light snow is expected to continue in
association with upper level trof crossing the region. Current
thinking is for snow accumulations to generally range from 2 to
4 inches through Monday evening. Higher amounts are possible
along the Maine/New Brunswick border from Northeast Aroostook
county southward into Northern and Central Washington county,
where amounts may approach advisory criteria by Monday evening.
That will be something for the midnight shift to take a look at
for possible advisory issuance. Steady snow will taper to
scattered snow showers across the region after midnight Monday.
The upper trof axis moves east of the region by Tuesday morning
with mainly cloudy skies expected across the north on Tuesday
along with a few lingering flurries, with partly sunny skies
downeast. The bigger concern on Tuesday will be the gusty
northwest winds due to the tightening pressure gradient between
the departing low to our east and high pressure building in from
the west. This will result in gusty northwest winds and
blustery weather conditions with the potential for some blowing
snow. In addition, moderately strong cold advection will result
in high temperatures Tuesday only reaching the low to mid 20s
north and mid 20s to around 30 downeast.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
After a mainly dry and cold Tuesday night, expect a moderating
temperature trend as we head into the mid to late week period.
Near seasonal temperatures are expected Wednesday along with dry
weather. Temperatures will then moderate on Thursday as milder
air begins to work into the area, as high pressure builds to
the east of the mid-atlantic region resulting in southwest flow.
The next storm system is expected to begin to affect the region
just in time for the winter solstice Friday. However, this
system looks like it will take a track well to our west allowing
plenty of mild air to move north ward, resulting in the
potential for a soaking rain Friday into Friday night. Looks
like a return to cooler weather behind that system as we go into
next weekend.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
NEAR TERM: A period of MVFR ceilings is likely late tonight into
Sunday morning at the northern terminals, otherwise VFR expected
through 00z Monday. There is the chance that there could also be
a little late night fog at the northern terminals, but
confidence on the fog is lower than the MVFR ceilings.
SHORT TERM: VFR can be expected at the Northern Terminals Sunday
night with IFR expected at KBGR/KBHB terminals after midnight in
developing snow. Widespread IFR expected Monday into Monday
evening all terminals in snow. Expect snow to taper to
scattered snow showers after midnight Monday. Expect MVFR/VFR
ceilings on Tuesday with scattered flurries or snow showers
possible northern terminals. The bigger concern will be the
gusty northwest winds that are expected Tuesday into tuesday
night. VFR conditions return for Wednesday and Thursday.
&&
.MARINE...
NEAR TERM: No headlines into Sunday. Decided on a blend of the
NAM12 and GFS for the winds and stayed close to the local wave
model for wave heights. Therefore, WNW winds turning to the NNE
overnight and then winds are expected to veer to the NE on
Sunday. Sustained speeds of 10-15 kts w/seas of 3-4 ft.
SHORT TERM: Winds/seas will increase toward SCA levels Sunday
night and Monday. Visibility will reduced to 1 to 3 NM in rain
and snow later Sunday night through Monday. Winds are then
expected to continue to increase Monday night into Tuesday
behind low pressure exiting to the east of Nova Scotia. A gale
warning will likely be needed Monday night into Tuesday.
&&
.CLIMATE...
The high of 46F this afternoon at Bangor was the warmest
observed since November 9th when the high was 48F. The high this
afternoon at Caribou of 39F was the warmest since November 24th
when the high was also 39F.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...CB/Hewitt
Short Term...Duda
Long Term...Duda
Aviation...CB/Hewitt/Duda
Marine...CB/Hewitt/Duda
Climate...
Area Forecast Discussion
National Weather Service Green Bay WI
536 PM CST Sat Dec 15 2018
Updated aviation portion for 00Z TAF issuance
.SHORT TERM...Tonight and Sunday
Issued at 210 PM CST Sat Dec 15 2018
The latest RAP analysis and satellite/radar imagery show high
pressure stretching from Texas to the Great Lakes early this
afternoon. Outside of some thin wispy cirrus dropping in from the
north, skies are mostly clear across the region thanks to ample
dry air at the surface and aloft. Looking to the west, a moisture
starved cold front is moving east across the northwest Plains.
With only mid and high clouds along the front, forecast concerns
mainly revolve around temps and fog potential.
Tonight...High pressure will continue to hang across the area
during the evening before shifting to the east overnight. A narrow
band of mid and high clouds will move from west to east overnight
along the front, but progged soundings indicate a dry atmosphere
below 15 kft. However, the pressure gradient will tighten along
the front, which should prevent temps from tanking and fog from
forming over central and north-central WI. Winds will be lighter
over eastern WI so could see some patchy fog develop there. No
significant changes to temps.
Sunday...The weak cold front will exit eastern WI by midday taking
most of the cloud cover with it. Some cirrus will likely still be
present overhead though should not impact temps much. Temps will
not be much colder behind the front, but should see highs fall
back a few degrees. Highs should range from the mid 30s to near
40.
.LONG TERM...Sunday Night Through Saturday
Issued at 210 PM CST Sat Dec 15 2018
The Canadian low pressure trough to the north of Wisconsin will
sweep east of the Great Lakes region on Monday and make way for a
high pressure ridge. The upper air pattern is shaping up to be
rather amplified and progressive during the first half of the week
though, and a low pressure trough will rapidly sharpen over the
Plains States by Thursday, prompting the development of a surface-
based low pressure system over the Lower Mississippi Valley. This
low will draw Gulf of Mexico moisture north and produce a decent
chance for mixed precipitation in Northeast Wisconsin late
Wednesday through late Thursday.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 536 PM CST Sat Dec 15 2018
There is a small chance that ground fog may form late
tonight, but otherwise it looks to be good flying weather through
Sunday night with mostly clear skies and light surface winds.
Low level wind shear is possible later tonight through 14z Sunday
in central and northcentral Wisconsin. Surface winds from the south
around 5 knots with southwest winds of 40 knots at 2000 ft agl.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......ML
AVIATION.......RDM
Area Forecast Discussion
National Weather Service Lincoln IL
850 PM CST Sat Dec 15 2018
.UPDATE...
Issued at 845 PM CST Sat Dec 15 2018
The storm system that produced the heavy rainfall over parts of
southeast Illinois last night into early this afternoon has
shifted into southeast Ohio with the rain area now off to our
east this evening. Weak high pressure will move into the area
bringing a clear sky and light winds, which should allow some
patchy fog to form across the area overnight. Already seeing some
light fog across our north and expect that trend to settle south
into the early morning hours. Quite a range in temperatures
overnight from the lower 20s over our far northern counties to
the mid or upper 30s over southast Illinois where residual cloud
cover and winds will help to keep the overnight lows up. What fog
we do see overnight should dissipate early Sunday morning with
another mild day shaping up with afternoon temperatures rising
into the upper 40s to lower 50s.
The current forecast has the overnight trends well in hand. Have
made only a few minor adjustments to the evening temperatures and
winds, otherwise, the rest of the forecast is in good shape. No
evening ZFP update needed.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 306 PM CST Sat Dec 15 2018
Deep upper low currently spinning over eastern Tennessee continues
to bring clouds and light rain to the southeast KILX CWA this
afternoon...mainly along/south of the I-70 corridor. HRRR has been
consistently showing the rain diminishing in intensity and
coverage late this afternoon, and this trend appears to be
verifying based on latest radar loops. Despite the drying trend,
showers upstream across central/southern Indiana will rotate W/SW
across the SE counties for the next several hours. Have therefore
maintained chance PoPs along/south of a Martinsville to Robinson
line through early evening...with showers coming to an end before
midnight. Meanwhile further west, clear skies and light winds will
lead to patchy fog development overnight. NAMNest is the most
aggressive model with patchy dense fog across the western two-
thirds of the CWA, while the RAP/HRRR show little to no fog.
Based on persistence, think at least patchy fog mention is
prudent. Do not think fog will become widespread/dense, as
slightly drier air trickling in from the N/NW will keep
temp/dewpoint spreads from bottoming out. Overnight lows will
range from the lower 20s northwest of the Illinois River...to the
middle 30s south of I-70. High pressure will bring ample sunshine
and light winds on Sunday...with afternoon highs climbing into the
upper 40s and lower 50s.
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 306 PM CST Sat Dec 15 2018
A weak cold front will pass through the region Sunday night,
resulting in a slightly cooler day on Monday with highs in the
lower to middle 40s. After another mild/dry on Tuesday, the next
chance for rain will arrive by the middle of the week. A pair of
short-wave troughs...one tracking across the Southern Plains and
the other ejecting out of the Northern Rockies...will phase over
the Midwest on Thursday. 12z Dec 15 models are in relatively good
agreement with this complex process, with all solutions signaling
a period of disturbed weather across central Illinois Wednesday
night through Friday morning. The atmosphere will initially be
warm enough for rain Wednesday night into Thursday, then will cool
sufficiently on the back side of the phased wave to support a
change to light snow late Thursday night into Friday morning. With
the bulk of the precip shifting into the Ohio River Valley and
low temperatures only dropping into the lower 30s Thursday night,
any wet snow accumulations will likely be minor. Once the precip
ends, cool/dry weather will be on tap for Friday afternoon into
Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 520 PM CST Sat Dec 15 2018
Main forecast concern this period will be the potential for fog
development late tonight. Storm system well to our southeast will
continue to push away from the forecast area tonight taking all
the rain with it to our south. Some low VFR cigs were just to
the east and south of DEC and CMI but are expected to shift
away from the area this evening. Otherwise, somewhat drier air
is forecast to advect south into the region tonight which should
limit the coverage of fog late tonight into early Sunday morning.
Will continue to carry 3-5sm vsbys in fog from about 09z-14z Sun
with VFR conditions expected across the area for the remainder
of the period. Northerly winds this evening will become light
and variable overnight and then gradually turn into the west and
southwest at 10 kts by Sunday afternoon.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Smith
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Smith
Area Forecast Discussion
National Weather Service New York NY
944 PM EST Sat Dec 15 2018
.SYNOPSIS...
A series of weak low pressure systems pass to the south of the
area through the weekend while high pressure remains centered to
the north. Low pressure departs to the northeast Monday as a
Canadian cold front passes through the area. High pressure
builds mid week. Low pressure tracks to the west late in the
week, as a warm front passes.
&&
.NEAR TERM /THROUGH SUNDAY/...
Based on current radar returns and HRRR and incoming NAM
guidance which seem to have a reasonable handle on the current
conditions, lowered POPs over the next few hours as high
pressure to the north is keeping the precipitation at bay for
now. Otherwise, only minor changes were made to reflect current
conditions.
Analyzed all available datasets to determine temperatures
forecasts overnight, and feel advisory for freezing rain is
fine, with main concern those interior zones. Temperatures early
this evening are a tad warmer than some of the higher resolution
guidance, but still feel there is potential for temps to fall to
or just below freezing across the advisory area.
Also, raised Pops to categorical as high confidence in
measurable rain.
Per previous discussion, primary concern into Sunday is the
potential for freezing rain to develop across far northern NJ,
the lower Hudson Valley and portions of western Connecticut.
Cold air damming at the surface as the high builds to our north
will allow temperatures to lower to right around freezing in
these areas. Coincidentally as the upper low nears, low level
warm advection will strengthen in strong easterly flow above the
surface, allowing a warm layer to develop between around
875-600 mb. As always, there is significant uncertainty
regarding the extent of cold air damming, but it is typical for
model forecasts to underdo the cold air, and then erode it too
fast once established. Trended on the colder side, more towards
the operational NAM, on temperatures, keeping forecast readings
near freezing through much of the day where a Winter Weather
Advisory is now in effect. The Cooperative Institute for
Precipitation Systems (CIPS) historical analogs reflect high
probabilities for freezing rain across the aforementioned areas,
lending some confidence towards a colder surface solution. It
is possible that freezing rain continues well into the
afternoon.
There are certainly two potential scenarios in which the
forecast could develop differently as well:
1. The colder/below freezing solution does not materialize, and
while a cold rain falls, freezing upon contact at the surface
does not occur.
2. As the upper low passes, colder temperatures aloft lead to
weak elevated instability, which may locally enhance precipitation
rates and even mix a bit of graupel in with the freezing rain.
If instability can develop, ice accumulations may be greater
than the 0.10-0.25 inch currently forecast for the advisory
areas.
Outside the advisory, confidence is low in both temperatures and
the expected amount of ice. A Special Weather Statement is in
effect highlighting the potential for ice in those periphery
areas, and should forecast/model solutions trend colder, then an
advisory may be needed.
Elsewhere, a cloudy rainy day is expected as the upper trough
finally moves over the area, with the main concern being breezy
conditions that will develop overnight and persist into Sunday.
Temperatures will range from 5 to 10 degrees below climatological
normals.
&&
.SHORT TERM /SUNDAY NIGHT/...
The upper low and an attendant coastal low quickly depart to the
northeast Sunday night in advance of a long wave trough,
allowing a cold front to move through the area. Any ongoing
precipitation may transition to snow as cold advection
strengthens, with quick but minimal accumulations primarily to
the north and west of the NYC area. Breezy conditions continue
behind the front, combining with lowering temperatures to make
it feel as though it is in the 20s overnight. Across the
interior - have extended the Winter Weather Advisory into Sunday
night to account for these additional potential accumulations.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Aloft, vigorous upper shortwave dives out of eastern Canada, quickly
passing across the northeast Monday into Tuesday. Ridge quickly
builds in for mid week. Next shortwave energy out of central Canada
will result in deepening longwave trough across the mid portion of
the country Thursday. This trough pivots east before lifting
northeast into eastern Canada by next weekend.
At the sfc, reasonable model agreement noted as deepening low
pressure moves northeast toward the Canadian Maritimes Monday. A
cold front passes late in the day. High pressure then builds Tuesday
and Wednesday.
By Thursday, low pressure develops over the Tennessee valley,
deepens and moves north across the Great Lakes region Friday into
Saturday. A warm front likely sweeps north Friday, followed by a
series of troughs Saturday.
As for sensible weather, any light wintry mix precip ends early
Monday morning. Do not foresee much precip with the upper shortwave
and associated cold front later Monday other than perhaps some
flurries. However, appears there is too much dry air to overcome.
Dry weather persists mid week thanks to ridging and associated
subsidence, then rain chances increase Thursday as deep southerly
flow and WAA commence, enhancing lift. Steadier rain likely impacts
the area Thursday night into early Friday based on timing from 12Z
model suite, with mid level drying likely lowering coverage Friday
afternoon through Saturday.
Near normal temps Monday will fall below seasonable Monday night and
Tuesday due to CAA behind the front. This will be short lived as
ridge builds, followed by deep south flow ahead of amplifying trough
to the west. Temps rise back to above normal Thursday-Saturday.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
A series of lows track to the south of Long Island into Sunday
evening, as high pressure to the north overnight, retreats to
the northeast during Sunday.
The high to the north was keeping precipitation and lower
conditions suppressed to the south, and indications are that
MVFR conditions will develop a couple of hours later than was
forecast.
VFR conditions remain until 06Z to 08Z, then lower to MVFR as
light rain becomes more widespread and steady. With
temperatures still well above freezing across the lower Hudson
Valley at 02Z, the chance of light freezing rain at KSWF is
reduced, and may not occur until closer to 12Z Sunday.
Uncertainty remains with how low surface temperatures across the
lower Hudson Valley will fall. If temperatures remain above
freezing overnight at KSWF, then plain rain will be likely.
IFR develops late overnight into early Sunday morning,
especially along the coast, periods of LIFR will be possible
during Sunday with moderate to briefly heavy rainfall.
Conditions gradually improve Sunday evening.
NE winds 10-15kt increase overnight with sustained winds of 15
to 20kt, highest near the coast. Gusts look to be more likely
overnight into Sunday with gusts 25 to 30kt. LLWS likely
Sunday morning with the strongest near the Long Island south
coast.
.OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY...
.Sunday night...MVFR/IFR in rain. There is the potential for
wintry mix across interior terminals as precipitation tapers
off, then becoming VFR late. NE to N winds G20-30kt mainly
across the eastern terminals.
.Monday-Monday night...VFR. NW winds G20-30KT probable.
.Tuesday-Wednesday night...VFR. NW Wind G15-20kt possible Tuesday, W-
WSW winds G15-20KT possible Wednesday.
.Thursday...VFR, possibly becoming MVFR or lower late with rain.
LLWS possible late.
&&
.MARINE...
East-Northeast winds and gusts quickly increase tonight into
Sunday as low pressure deepens along the coast and high pressure
remains to the north. The strongest low-level winds are expected
into Sunday afternoon, where there is potential for isolated
storm-force winds to mix to the waters. A gale warning is now in
effect for all waters.
Although winds decrease somewhat Sunday night as the low passes
along the coast, it is likely SCA-level winds will continue, and
seas will remain elevated on the ocean waters.
Winds temporarily diminish early Monday as the low departs to
the Canadian Maritimes. A cold front passes across the waters
late Monday, and winds increase once again Monday night into
Tuesday. In fact, gale force winds are possible once again.
Winds will diminish Tuesday night through Wednesday as high
pressure builds. Winds shift around to the S/SE Thursday, and
will increase late in the day ahead of deepening low pressure to
the west.
Rough seas Monday and Tuesday are expected to subside mid week as
the winds diminish. Seas build late Thursday and Thursday night.
&&
.HYDROLOGY...
Between 0.50" and 1.25" of rainfall is then expected late
tonight through Sunday night. The highest rainfall amounts are
currently expected across portions of northeastern New Jersey,
NYC, and Long Island. A period of moderate to heavy rainfall
will be possible Sunday morning. Low chances of minor
nuisance/poor drainage flooding will be possible during the
daytime on Sunday.
Next chance for significant rainfall of at least a half an inch will
be late in the week. Too early to determine if there will be any
hydrologic concerns with this potential late week event.
&&
.EQUIPMENT...
NYC Central Park winds are out of service until further notice.
Loss of data is due to a severed cable. Parts are on order.
NYC NOAA Weather Radio Station KWO35 (162.55 MHz) will remain off
the air for an extended period of time.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Winter Weather Advisory until 6 AM EST Monday for NYZ067-068.
NJ...Winter Weather Advisory until 6 AM EST Monday for NJZ002.
MARINE...Gale Warning until midnight EST Sunday night for ANZ330-335-
338-340-345-350-353-355.
&&
$$
SYNOPSIS...MD/PW
NEAR TERM...MD/JP/PW
SHORT TERM...MD
LONG TERM...PW
AVIATION...MET
MARINE...MD/PW
HYDROLOGY...MD/PW
EQUIPMENT...
Area Forecast Discussion
National Weather Service Charleston WV
1016 PM EST Sat Dec 15 2018
.SYNOPSIS...
Rain continues as upper low moves into region. Cooler air moves
in behind the system for the beginning of next week. High
pressure mid week. Another system due late next week.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 1015 PM Saturday...
Precipitation across sotuhern WV into the Tri-state is more
broken than previous expected. Have reworked POPs leaning
heavily on the HRRR through the night. Do expect this to fill
back in as the next wave of forcing drifts through.
As of 100 PM Saturday...
Frontogenetically forced band of light occasionally moderate
rain will continue across southeast OH and northern WV into the
afternoon hours. This will move north thereafter across northern
WV at least, with a bit of a lull taking hold across a good
chunk of the CWA. However, rain will overspread the area again
this evening, as lift associated closer to the center of the
upper low pivots north from southern and eastern KY. Some
elevated instability across far southern counties could also
result in some convective elements to enhance rains. In addition
a weak surface low will traverse the area, providing additional
lift via low level convergence.
Generally .75 to near 1 inch has fallen across the area since
last night. An additional half inch to inch is expected tonight,
primarily across southeast OH and adjacent northern WV lowland
counties. Given that most of this will occur as runoff, creeks
and low lying areas will be vulnerable to flooding which could
result in road closures. Even though this is somewhat of a
prolonged event, given the impacts we typically see across those
locations in the cool season with the forecast QPF, I elected
to hoist a flood watch into Sunday morning.
The upper low moves east of the area on Sunday, taking the
steadier rains with it. In its wake will be areas of drizzle
and/or light rain, tapering off in the afternoon. The exception
being across the mountains where lingering orographic lift and
low level moisture will keep the threat of light precipitation
going. Meanwhile, the column will be cooling such that a
transition to light freezing rain/drizzle across the high
eastern ridges of Raleigh County is possible heading into Sunday
morning, spreading into the ridges in Pocahontas County during
the afternoon. I will hold on any winter weather advisory for
now, given the uncertainty with just how cold the air will be
at the surface.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 200 PM Saturday...
Shallow, low-level moisture remains across the area at the start of
the period and wanes from West to East through Sunday night. General
NW flow through the column continues to bringing in cooler air
leading to a cooler Monday morning. This regime keeps light rain and
drizzle, freezing drizzle for some across higher elevations, through
the night.
A reinforcing cold front drops down Monday afternoon into the
evening, bringing renewed, albeit low, precipitation chances across
higher terrain with effective upslope flow in spite of only shallow
moisture availability. Latest model soundings show a hint of crystal
growth, so a few flakes may mix into otherwise drizzle/freezing
drizzle along highest ridgelines Monday night. Favorable
upslope winds erode by Tuesday morning and high pressure builds
from the Great Lakes region, gradually clearing conditions
through Tuesday.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 210 PM Saturday...
With high pressure overhead, clear, calm skies allow for a cold
Tuesday night/Wednesday morning with lows in the 20`s. High
pressure shifts to the East with an approaching ridge, allowing
southwesterly return flow to take hold, ushering in a warming
and moistening trend through Thursday. High temperatures reach
well into the 40`s (mountains) and 50`s (lowlands) Wednesday and
Thursday, with some locations perhaps flirting with 60 on
Thursday should cloud cover be less widespread than currently
forecast.
Attention then turns to the system approaching the area at the
end of the work week. Models agree on a deeply amplified trough
axis traversing the CONUS, arriving East of the Mississippi by
Thursday. Warm frontal rain showers associated with the system
start to arrive mid-Thursday and will depend on timing of said
front, possible downsloping eating into precip chances in the
western lowlands, and moistening of the boundary layer. Major
long-range models agree that the low will track up through this
area from the SSW to NNE on Friday, occluding as it does so,
with continued rain shower activity. Main uncertainty during
this phase would be the presence of or lack of a dry slot
modifying available moisture. Winds turn northerly and cold air
filters in behind the system center Friday night, so a wintry
mix is possible at least across the higher terrain as the system
exits heading into the early part of the weekend.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
As of 650 PM Saturday...
A rain band will pivot across PKB, CKB and EKN with MVFR ceilings
and MVFR to IFR visibilities. Another band sweeps north into
the forecast area through late tonight. This will cause
visibilities and ceilings to fluctuate as well. Looks like most
sites will stay IFR until ceilings lift Sunday afternoon.
Thinking patches of fog and drizzle will develop late tonight
and linger through tomorrow afternoon.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z MONDAY...
FORECAST CONFIDENCE: Low.
ALTERNATE SCENARIOS: IFR vsby may be more intermittent and less
predominate tonight. Timing improving conditions on Sunday may
vary from forecast a few hours.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE SUN 12/16/18
UTC 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14
EST 1HRLY 22 23 00 01 02 03 04 05 06 07 08 09
CRW CONSISTENCY H H M M M M M H H L M M
HTS CONSISTENCY L L M M M H H M M H L L
BKW CONSISTENCY H H M L M M M H H H M M
EKN CONSISTENCY L H H H H M M M M L H H
PKB CONSISTENCY H H L M H L L H H H H H
CKB CONSISTENCY M M L H H M M M M M H H
AFTER 00Z MONDAY...
Periods of IFR possible in rain or stratus through Sunday
night, and in mixed wintry precipitation and stratus in the
northern WV mountains at times Sunday night into Monday night.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Flood Watch until 10 AM EST Sunday for WVZ007>011-017-019.
OH...Flood Watch until 10 AM EST Sunday for OHZ066-067-075-076-
083>086.
KY...None.
VA...None.
&&
$$
SYNOPSIS...30/MC
NEAR TERM...MZ/30
SHORT TERM...MC
LONG TERM...MC
AVIATION...MZ/JZ
Area Forecast Discussion
National Weather Service Blacksburg VA
654 PM EST Sat Dec 15 2018
.SYNOPSIS...
An upper low will slowly progress into the central Appalachians
tonight and lift northeast Sunday. A brief period of upslope rain
and snow showers are possible Monday night across the western
mountains. Drier weather as high pressure builds in Monday night
through midweek. Above-normal temperatures are expected through the
weekend into much of the upcoming workweek.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 630 PM EST Saturday...
Last batch of rain is heading north of I-64 this evening. Some
drizzle, but mainly areas of fog is forming in the wake of this
precipitation. The upper level low is expected to track across
the Tennessee Valley to the southern Appalachian Mountains by
midnight. Increase mixing as winds turn to the northeast should
scour fog across the mountains during the early morning hours.
This mixing may not occur over the piedmont until around sunrise
and fog may hamper early morning commuters.
As of 252 PM EST Saturday...
Canceled Flood Watch with the heavier rain over and much of the snow
pack melted or gone. A general 1 to 2 inches of rain fell
across areas east of the Blue Ridge during the last 36 hours.
flooding concerns shift to larger river. See Hydro section.
Vertically-stacked low pressure centered over Tennessee this
afternoon will lift northeast tonight into Sunday. The upper low
and its inverted trough will move across the Appalachians tonight.
HiResW-ARW-east and HRRR captures the scattered showers this
afternoon, especially central portions of forecast area which
lift north this afternoon into tonight. Then, the rain will become
more focused in wrap-around fashion to the north and west of the
trough axis, mainly across the mountains. Northwest winds at
elevation will begin to increase tonight as well, but gusts should
be below 30 kts. Low temperatures tonight will vary from the mid 30s
in the mountains to the lower 40s in the piedmont.
Widespread low clouds, fog, and drizzle are likely Sunday morning as
the weakening vertically stacked upper low drifts into northern
Virginia. For Sunday afternoon, the best chance of rain will occur
in the mountains with weak upslope component, upper troughing, and
weak cold advection. While in the east, precipitation should end and
conditions slowly improve as the day progresses. High temperatures
Sunday will average above normal with readings from around 40
degrees in the west to the lower 50s along the southern Blue
Ridge.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 330 PM EST Saturday...
Monday, the upper low will lift more quickly to the northeast
and away from the area as a northern stream trough picks it up
off the New England Coast. Shortwave ridging will then edge
eastward into the Midwest with dry northwest flow evolving
across our region. After a breezy day Monday (85h flow of 40
kts is indicated by most models), anticipating trend toward fair
weather for a few days as surface high pressure builds
overhead, yeilding clear skies and diminishing winds by Tuesday.
As the area of high pressure builds into the area Monday, cold
advection in the northwest flow is modest at best for this time
of year with no source of Arctic air. Impact to temperatures
will be very little. If anything they may end up slightly above
normal.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 330 PM EST Saturday...
Dry conditions with above seasonal temperatures expected for
Wednesday and Thursday. The upper flow will become increasingly
more amplified by the end of the week with another healthy
looking southern stream trough to evolve from the southwest.
This promises to provide another round of widespread rainfall
as it taps Gulf of Mexico moisture Thursday into Friday.
A bit more phasing with the northern stream is progged with this
system as it exits the region Saturday, which will bring colder
air into the region for the weekend. However, aside for some
snow showers or flurries in the mountains, no significant
accumulation is anticipated. Unless there is a change in the
upper air pattern, the remnant dirty snow piles appear to be
the only snow that we will be looking at on the ground between
now and Christmas Day. The best chance for any light
accumulation of snow this weekend would be the higher elevations
west of the Blue Ridge, mainly elevations above 3500 feet.
Details with respect to timing and rainfall amounts Thursday
and Friday are still in flux. Weather hazards for our forecast
area would be centered around potential flooding. Most of the
snow melted with this last storm system, so snowmelt is not
expected to be a concern. If there is a need for a Flood Watch,
it will revolve around QPF and the wet antecedent conditions.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 645 PM EST Saturday...
Poor flying conditions (IFR to LIFR) expected with low clouds,
drizzle and fog tonight.
The last batch of rain is moving north towards the I-64
corridor. In the wake of this precipitation, areas of fog and
low clouds have formed across the area. As an upper level low
tracks to the southern Appalachians overnight, mixing will
increase across the mountains and foothills. This mixing should
improve visibilities, while IFR ceilings hang around until
morning. Across the piedmont, mixing is not expected until mid
Sunday morning. All areas should see improving conditions to VFR
Sunday afternoon. Light rain is also expected across the
mountains as the upper level low moves east of the area and
winds become westerly.
Forecast confidence is medium to high on ceilings, visibilities
and winds through 06Z Sunday.
Extended Aviation Discussion...
A transition to VFR expected Monday and Tuesday as drying takes
place. VFR conditions will continue Wednesday. MVFR showers
will return on Thursday.
&&
.HYDROLOGY...
As of 650 PM EST Saturday...
Rainfall of 1 to 2 inches in the last 36 hours has fallen
across the Lower Roanoke and Dan River Basins. This runoff,
combined with snowmelt, will cause significant rises along the
Roanoke and Dan Rivers through Sunday with minor flooding
likely, especially for lowland farmlands, Brookneal to Randolph.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...AL
NEAR TERM...KK/RCS
SHORT TERM...PM
LONG TERM...PM
AVIATION...KK/RCS
HYDROLOGY...RCS