Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/08/19
AREA FORECAST DISCUSSION
National Weather Service Albany NY
956 PM EST Thu Feb 7 2019
.SYNOPSIS...
Rain will continue across eastern New York and western
New England overnight with isolated thunderstorms also possible
ahead of a warm front. It will turn blustery and colder tomorrow
into Saturday with some lake effect snow likely. Seasonable
temperatures with increasing clouds for Sunday.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 955 pm EST...A region of upper level diffluence continues
to be over the region ahead of a strong upper level trough.
Deepening sfc low pressure according to the latest RAP is 992
hPa moving into south/southeast Ontario. The isentropic lift
continues to increase over the forecast area with mainly light
to occasionally moderate rain overspreading it ahead of the warm
front. A brief lull is possible over the southern most zones,
but that should fill in quickly again based on the latest 3-km
HRRR.
Some higher elevation sites remain near freezing over the
southern Greens and extreme northern Berkshires. We did issue a
Special Weather Statement for a brief period of freezing rain to
around midnight for some light ice accretions at elevations
2000 feet or greater. Temps remain mainly in the lower to mid
30s to lower to mid 40s. They should be steady or slowly rise
overnight.
The strengthening low-level jet should help some warmer air
reach these higher elevations. Also, the 00Z NAM continue to
have Showalter stability indices 0 to -2C especially over the
southern zones. We changed the slight chance of thunderstorms
back until after midnight. A rumble or two is possible with the
elevated instability.
Previous near term...
AN upper-level trough which will become sharply negatively
tilted and close off as we head into the overnight. This will
result in the low deepening as it as it tracks toward James Bay.
Attendant low- level jet in the warm sector will spread into
the area with another surge of moisture as PWATs increase to
1-1.25 inches throughout the forecast area. This is +3 to +5
standard deviations per the NAEFS. Fortunately, this system is a
rather quick-hitter, so do not expect excessive QPF (see hydro
discussion below). Some showers are also possible ahead of the
approach of a strong cold front very late tonight into Friday
morning. Showalter indices go slightly negative overnight, so
we could hear a rumble of thunder or two, with locally heavy
downpours possible. Temps will remain steady or rise somewhat
late tonight, quite mild in the mid-30s to mid- 40s.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Wind Advisory in effect for portions of the southern
Adirondacks, Mohawk Valley, Schoharie Valley, Capital District,
and Helderbergs 1 pm Friday through 1 pm Saturday...
A strong cold front Friday morning will drop H850 temps by
around 15-20C in 12 hours. While temperatures at the surface
may spike early in the morning immediately behind the front due
to mixing, strong cold advection should drop temperatures in
most areas by the afternoon. A strong post-frontal pressure
gradient will set up with deep mixing encouraged by robust cold
air advection. Forecast soundings suggest average wind speeds in
the mixed layer increase to 30-40 kt Friday afternoon through
early Saturday afternoon, with winds at the top of the mixed
layer reaching about 50 kt. 6-hour pressure rises are around 5-8
mb from around 18Z Friday to 06Z Saturday, which is
respectable. The core of the strongest winds aloft moves in
Friday night past the diurnal maximum, but continued cold air
advection may continue to support downward momentum transport
overnight. While forecast gust values are borderline for
advisory criteria, they will occur over a rather long period. A
Wind Advisory was issued for the Mohawk Valley/Southern
Adirondacks, as well as the Capital District into which the
winds tend to funnel from down the Mohawk Valley. The advisory
may need to be expanded into portions of the Taconics/western
New England, but will hold off for now per collaboration with
surrounding offices.
Most of the precipitation from tonight`s system should have
moved east by the time the colder air moves in. However, lake
effect parameters will become increasingly impressive Friday
afternoon into Friday evening, with surface to 850 mb delta-Ts
increasing to 20C and inversion heights up to 2 km. Winds in
the 0-3 km layer will be veering with time, so do not expect a
band to remain stationary over a period of time, which should
limit accumulations. Late Friday night into Saturday morning,
local inland extent program supported by CSTAR research is
indicating values near 170 miles, so we could even see a band
reach the Capital District to western New England briefly. Wind
chills Friday night likely will fall into the single digits
above and below zero.
Saturday will be continued blustery and seasonably cold,
although expanding high pressure will result in sunshine and
winds diminishing in the afternoon. The associated subsidence
should quickly put an end to any lingering lake effect activity.
Highs in the 20s to lower 30s will be back a bit below normal
values.
Saturday night looks somewhat favorable for radiational cooling,
although the center of the strong 1040 mb high will be located
to our south over the Mid-Atlantic. Lows in the single digits
and teens will be common, with some below-zero readings over the
higher terrain. Seasonably cold and tranquil conditions
continue Sunday, with clouds increasing late as the high shifts
offshore.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
The highlight of this period will be a possible major winter event
toward mid-week. Things start off dry with high pressure stretching
from western Canada all the way to the northeastern U.S. Sunshine
will be the rule on Monday. Meanwhile low pressure is expected to
develop off the Colorado Rockies, broaden and intensify as it makes
its way towards the northeastern U.S.
Models are pretty much in lock-step concerning progression of this
system and the fact that it will pretty much all snow. But each
model suggests moisture is limited, and only the GFS hints at a
marginally major snow event. The relatively low-predicted QPFs is
probably because the low is expected to split its energies between
the main interior low and a secondary low expected to intensify off
the northeast coast as it tracks up toward Cape Cod. So despite its
expected widespread impact, being it`s almost a week off, have kept
PoPs down in the chance category for this event.
From late Wednesday on, precipitation mainly in the form of snow
will be limited to the lake effect regions on a westerly flow behind
the departing storm. Lake effect cloudiness, however, will likely
impact the entire forecast area, though not so profoundly across the
southern zones.
Daytime highs Monday will range from the upper teens in the
Adirondack high peaks...to the upper 30s in the Mid-Hudson Valley
and southern zones. For Tuesday, the high peaks will moderate by
several degrees while increasing clouds result in a slight cooldown
across the south. Downsloping on westerly winds behind the cold
front of the departing storm will spell a warmer day for Wednesday
with snow showers turning to rain showers at most locations before
the cold air finally intrudes to change things back as the activity
winds down. Highs Wednesday are expected to range from around 30
degrees to the mid 40s. Highs Thursday will range from the mid 20s
to around 40 degrees.
Sunday night lows will range from the upper single digits to mid 20s
while Monday night lows will range from the lower single digits to
upper teens. Upper teens to upper 20s will be the general rule for
Tuesday night; upper teens to mid 20s for Wednesday night.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Localized IFR conditions in fog can be expected at the TAF sites
through about 02z, especially at GFL and POU, then rain will
overspread the area around 02z with mainly MVFR conditions in
rain and light fog. Areas of IFR will likely develop again late
tonight as fog becomes more dense and cigs gradually lower. In
addition, a period of low level wind shear can be expected this
evening into the early morning hours with 30 to 35 kt southerly
winds expected at above 2000 AGL and light winds at the
surface.
A cold front will move across the area Friday morning ending the
rain with conditions improving to widespread VFR with clearing
by noon. Light winds will become westerly and increase to 15 to
25 kts with gusts to 30 kts during the afternoon.
Friday Night: Moderate Operational Impact. Windy With Gusts To 38.0 Slight Chance of SHSN.
Saturday: Moderate Operational Impact. Windy With Gusts To 38.0 NO SIG WX.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: Low Operational Impact. Slight Chance of SHSN.
Monday: No Operational Impact. NO SIG WX.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: Moderate Operational Impact. Chance of SN.
&&
.HYDROLOGY...
Another storm system will bring rain to the area tonight. Total
QPF from this system is expected to mainly range from 0.25 to
0.75 inches. The modest snowmelt coupled with the modest
rainfall should result in river rises. Some rivers are forecast
to reach action stage, but as of now, no flooding is forecast.
However, areas where ice jams exist will need to be monitored,
as it is possible that the river rises could allow the ice to
move, resulting in new ice jam flooding. Locally heavy downpours
are possible tonight with isolated thunderstorms.
By Friday into the weekend, temperatures will be back toward or
below seasonal levels (mainly below freezing) with dry weather
expected aside from light to moderate lake effect snow, which
should once again promote ice formation and allow river levels
to fall.
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...Wind Advisory from 1 PM Friday to 1 PM EST Saturday for NYZ032-
033-038>040-047>053-082.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Thompson/Wasula
NEAR TERM...Thompson/Wasula
SHORT TERM...Thompson
LONG TERM...ELH
AVIATION...MSE/Speciale
HYDROLOGY...MSE/Thompson
Area Forecast Discussion
National Weather Service Denver/Boulder CO
815 PM MST Thu Feb 7 2019
.UPDATE...
Issued at 815 PM MST Thu Feb 7 2019
Forecast looks on track tonight other than the minimum
temperatures. As expected the skies have almost completely
cleared out across the area save some lingering capping clouds
along the Divide. Winds across the Plains, especially along and
east of I-25 north of Denver and along I-76 northeast of Denver to
around Sterling have diminished, resulting in ideal raditional
cooling processes. The areas with good snowpack are seeing
temperatures already dropping like a rock with several obs showing
-10 to -14 in southern Weld County, and Akron has already hit -8.
Even our best numerical models have no idea how to capture the
cooling rates. It will be a game of cat and mouse all night
tonight with winds vs temperatures. If the winds stay up, the low
temps will generally be in the single digits. If the winds go
calm for an hour or two in a row before 8 AM, lows will be
between 0 and -15. We`ve relied heavily on current observations
to identify where the best radiational cooling is already
occuring. Right now that is Weld County and the South Platte
Valley into Logan County. Washington County too. Along I-25 north
of Denver is also already colder than originally forecast and
much colder than any model predicted. We`ve updated the grids
with new overnight lows for tonight, generally undercutting
previous forecasts by 4-10 degrees where we expect winds to
remain light. Along the Palmer Divide, within and right next to
the foothills, and across much of metro Denver (other than DIA),
the minimum temperatures between 0 and 10 look good for now.
There should be enough downslope and weak drainage winds plus
urban effects to keep those areas from dropping too far.
&&
.SHORT TERM...(This evening through Friday)
Issued at 234 PM MST Thu Feb 7 2019
Satellite pictures are showing mostly cloudy skies over the CWA
right now. Area radars indicate some snow showers developing over
the mountains. Not sure how much snow is hitting the ground,
mostly just flurries. Models have west-southwesterly 60-80 knot
jet level flow for the CWA overnight. The jet level flow is
southwesterly on Friday. The QG Omega fields have downward energy
tonight, then weak upward vertical velocity on Friday. The low
level wind and pressure fields show weak drainage wind patterns
tonight over the plains. There is a bit of a mountain wave set-up
tonight, kind of up high, but certainly decent downslope from the
divide into the foothills. On Friday, southerly flow is progged
over most of the plains. The rest of the CWA had weak flow level
flow. For moisture, this afternoon`s cloudiness will be short
lived. Cross sections show it to be pretty dry tonight and Friday.
Th QPF fields show no measurable precipitation for the CWA through
Friday after 03Z this evening. There is a tad in the high
mountains early this evening. The thickness fields already show
the cold airmass to moderate overnight and Friday`s highs look to
be 5-10 C warmer then today`s readings.
.LONG TERM...(Friday night through Thursday)
Issued at 224 PM MST Thu Feb 7 2019
A low pressure center over the Pacific coast of CA will bring SW
flow over the state through Saturday. Warm air advection will
continue helping to increase temperatures. Conditions will continue
to be dry Saturday with highs in the lower 40s across the plains. By
Saturday night, the system over CA will progress into the Great
basin as a positively tilted trough. There is moderate levels of QG
with this system as a 130+ jet moves into central CO with the right
entrance region over the NE. This will promote good lift and
instability Saturday night into Sunday morning. Moisture will
increase through the mid and upper levels that will help to bring
snow showers to the mountains Saturday night and continue through
Sunday morning. For the Plains, models are showing another surge of
cold air dropping out of Canada that will impact CO Saturday into
Sunday. Model upper air soundings show a saturated profile through
500 mb that would help to promote dendritic growth and allow for
some light snow overnight Saturday. Will keep a slight chance of
snow for the plains through Sunday morning with overnight lows in
the teens. Temperatures will have to be monitored to account for the
arctic air and how low it could bring temperatures during this
period.
By Sunday, the disturbance will have moved off to the NE leaving CO
once again in SW flow aloft. Cooler air will prevail on Sunday with
moderate subsidence and clearing. Models currently have highs in the
30s, but may have to drop lower. For Sunday night into Monday,
another upper level disturbance will move SE from the Pacific NW and
will be pushing through Utah Monday morning. This will increase
moisture over Western CO and the central mountains bringing another
round of snow to the high country. Temperatures will remain around
normal for the plains with highs in the lower 40s. Entering into mid-
week ridging will increase with a period of dry and slightly warmer
weather into Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 815 PM MST Thu Feb 7 2019
VFR conditions through Friday. Need to mention the cold
temperatures again tonight with 0 to -5 at DEN and between 0 and 5
above at BJC and APA. Winds should be in the 10 kt range out of
the south at DEN until 12-14Z or so, then go light and variable.
Expect weaker south winds at APA, while at at BJC they will
probably remain light and variable tonight into midday Friday
though west is the best direction to go with. Winds should pick up
and settle on a preferred direction by 18Z, but the certainty on
what that direction will be is muddied by the formation of a
Denver Cyclone. Strong southerly flow across the Palmer Divide
should spin up the cyclone between 18 and 19Z or so. The HRRR has
been reasonably consistent at putting the cyclone and it`s line of
convergence south and east of DIA. This would mean NNW winds at
BJC and APA, while at DEN it they may start off ENE midday then
turn to N and NNW thoughout the afternoon and evening as the
cyclone migrates off further to the east of DEN. By 01 or 02Z
Friday evening winds should weaken across the metro area terminals
to 5 kts or less, and probably be variable direction. Tried to
handle the turning winds at DEN in the TAF but confidence in the
precise timing of the shifting winds is low, just hoping to get
the overall pattern correct at this point in time. Drainage winds
(SSW at DEN, S at APA, W at BJC) will get going again after 03Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Schlatter
SHORT TERM...RJK
LONG TERM....Bowen
AVIATION...Schlatter
AREA FORECAST DISCUSSION
National Weather Service Burlington VT
938 PM EST Thu Feb 7 2019
.SYNOPSIS...
Very changeable weather and temperatures anticipating the next 12 to
24 hours, before much cooler air arrives for the weekend. Tonight
rain with areas of freezing rain will redevelop across the North
Country as temperatures slowly warm above freezing in most
locations. Ice accumulations up to a tenth of an inch possible,
especially northern Saint Lawrence Valley and east of the Green
Mountains. On Friday, temperatures briefly jump into the 40s, before
a strong cold front with very gusty winds produce sharply falling
temperatures in the afternoon. Blustery and cold conditions with
mountains snow showers develop Friday afternoon into the upcoming
weekend.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 938 PM EST Thursday...Precipitation now making its way
into the region. Temperatures are mainly above freezing and the
precipitation will be rain...but where we have the advisories
over the Saint Lawrence Valley of New York and areas east of the
Greens in Vermont temperatures are either at or just below
freezing. Thus freezing rain advisory continues to look good.
Did issue a special weather statement earlier for parts of far
northeast New York and far northwest Vermont where some light
freezing rain is also possible as temperatures are slow to climb
above freezing in this area. Could see a little freezing rain
that produces a very light glaze on road surfaces making for
slick travel. Rest of forecast in good shape.
Previous Discussion...
Winter Weather Advisories continues for freezing rain in the
Saint Lawrence Valley and eastern Vermont tonight.
Wind advisory has been issued for northern NY and most of central
and eastern VT, including the Northeast Kingdom from 7 AM Friday to
10 AM Saturday.
Water vapor shows digging mid/upper level trof acrs the central
CONUS with ribbon of enhanced mid level moisture advects toward the
ne conus. This moisture and dynamics from trof and associated jet
will produce a period of rain tonight across the North Country.
However, northeast winds continue to advect low level cold air down
the slv with temps only in the mid 20s, so anticipate areas of
freezing rain. Meanwhile, east of the greens temps will drop below
freezing this evening, with pockets of freezing rain likely as the
rain develops btwn 02-04z. Unlike yesterday we expect the precip to
arrive aft the evening rush, so anticipating a better evening
commute across the region. Winter wx advisories continue for the SLV
and eastern VT tonight. Across the northern CPV (Clinton,
Chittenden, Grand Isle and Franklin counties, thinking a few pockets
of freezing rain is possible with initial surge of moisture, but
winds quickly shift to the south/southeast btwn 00z-03z and I think
temps will warm above freezing, so no advisory. However, if wind
shift is delayed and temps are at or below freezing some pockets of
freezing rain possible, especially northeast Clinton County. Unlike
yesterday, qpf will be lighter this event with precip ranging from
0.10 to 0.30 of an inch and total ice accumulation up to a tenth of
an inch in the advisory areas. Temps will be complex and challenging
with lows generally this evening, before warming occurs after
midnight with many locations above freezing. Lows mid 20s
SLV/northern CPV to near 30F east of Greens to mid 30s
midslopes/ridges with readings warming into the mid 30s to mid 40s
by sunrise. Would not be surprised a few readings near 50f across
the western dacks/slv near Potsdam/Canton areas.
Friday-Friday Night...A mature sub 980mb low pres will quickly lift
across the northern Great Lakes and toward Hudson Bay by 18z Friday.
Precip will quickly end by 12z as well defined mid/upper level dry
slot develops from west to east. This dry slot combined with
steepening low to mid level lapse rates associated with strong llvl
caa will produce strong/gusty west winds. 15z Rap soundings show
bottom of the mixed layer btwn 40-45 knots across northern NY by
noon on Friday, which spreads into Vt on Friday aftn/evening. Have
noted gusty winds come in several surges with 1st surge btwn 15z-21z
Friday, next period around 03z, with the potential strongest surge
occurring btwn 09-15z Sat associated with 850mb winds of 60 to 70
knots. Based on this have issued wind advisory for northern
Dacks/SLV and locations east of the Greens in VT from 12z Fri to 15z
Sat for localized wind gusts up to 50 mph. Thinking strongest wind
gusts will be on the east side of the Green Mountains from Ludlow to
Waitsfield to Stowe to Newport, with secondary axis of strong winds
across the Northeast Kingdom and parts of the lower CT River Valley.
Meanwhile, localized gusts up to 50 mph are expected over portions
of the SLV and downslope regions of the northern and eastern
sections of the Adirondack Mtns. Isolated power outages are possible
in the advisory areas from Fri morning into Sat.
Expecting a roller coast ride in the temp depart on Friday with
warmest values in the morning, before strong cold air advection
develops and temps tumble. Based on thickness values reaching 550 to
552 and progged 850mb temps btwn 6-8c around 10z Friday, would not
be surprised a few sites touch 50f or so, especially in the
southwest to southeast downslope regions. Temps will quickly come
crashing down by 18z Friday, with 925mb to 850mb values falling
below 0c and near -15c at 850mb by 00z Saturday. Temps should be
below freezing all locations by 00z, with summits in the single
digits to mid teens. Any precip will become scattered and confined
to the mountains on Friday into Friday night. Upslope snow will be
limited as moisture profiles and associated qpf are minimal. Maybe
an inch or two across the northern Greens and portions of the
western Dacks. Some lake effect snow showers are possible as flow
aligns off Lake Ontario and colder thermal profiles develop,
especially on Friday Night.
Given short duration warm up and qpf amounts generally under
0.50 not expecting any hydro related issues. However, cannot
completely rule out minor low lying flooding associated with an
isolated freeze up jam on a local waterway.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
As of 253 PM EST Thursday...The weekend will be cold and dry as high
pressure settles across the North Country. A few snow showers
may linger in the Northeast Kingdom Saturday morning, but
overall anticipate drying as moisture decreases behind low
pressure departing over the Maritimes. Skies will gradually
clear as well, but temperatures will only top out in the teens
and 20s for highs. It`ll be quite windy as well, with a 50+ kt
850mb jet skirting across the region. This combined with mixing
due to cold air advection will result in brisk west to northwest
winds through at least the first half of the day, gradually
subsiding late in the afternoon and evening. Winds will continue
to lessen overnight Saturday night as high pressure builds in
and the pressure gradient relaxes. Lows will be in the single
digits, below zero in the Northeast Kingdom and Adirondacks and
above zero elsewhere. Sunday will see increasing clouds and
temperatures a few degrees warmer than Saturday`s readings.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 253 PM EST Thursday...Things become a bit more active for next
week as the high builds to the east of the region. A shortwave
trough will rotate through the quick flow aloft. The GFS is a
bit more amplified with this feature and produces some light QPF
across our region Sunday night, while the ECMWF and CMC both
keep the best forcing with the shortwave to the north. Have
stayed with just low chance PoPs at most for this time period.
Either way, the high becomes reestablished for Monday and Monday
night, with dry weather to prevail. Our next best chance for
precipitation arrives Tuesday as an upper trough digs to our
west. Surface low pressure will scoot across the Great Lakes
while a secondary low develops off the Mid Atlantic coast
Tuesday night. These two lows will both shift northeast, so the
question will be the relative strength and placement of the
secondary low and hence mixed precipitation potential. At this
time, the secondary low is of sufficient strength and is far
enough east to keep cold air across the North Country, resulting
in just snow for later Tuesday and Tuesday night. However, if
the primary low is able to advect warm air northward into
northern New England before the secondary takes hold, a wintry
mix will be possible. There has been some run-to-run differences
with these two scenarios, so this system will need to be
monitored. Regardless, once the lows move to our east, we`ll see
northwest flow and upslope/mountain snow showers Wednesday into
Thursday. Temperatures through the period will be near to below
normal.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Through 00Z Saturday...A wide range of conditions exists with
IFR to LIFR ceilings across the area and MVFR to LIFR
visibilities. Through 04z there will be periods of VLIFR
ceilings and visibilities across northern New York before the
precipitation moves in. As precipitation spreads from southwest
to northeast it will be a mix of rain and freezing rain before
transitioning to all rain between 06z and 10z. The precipitation
moves east of the area between 10z and 14z...which is when
ceilings and visibilities improve sharply into the VFR category.
At that time winds will start to get gusty from the south and
southwest...with windy conditions develop between 18z and 20z as
winds become more westerly and we see gusts in the 25 to 35 knot
range for the remainder of the period.
Outlook...
Friday Night: VFR. Windy with gusts to 35 kt. Slight chance SHSN.
Saturday: VFR. Windy with gusts to 30 kt. NO SIG WX.
Saturday Night: VFR. NO SIG WX.
Sunday: VFR. Slight chance SHSN.
Sunday Night: Mainly VFR, with local MVFR possible. Chance SHSN.
Monday: VFR. NO SIG WX.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. Chance SN.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Winter Weather Advisory until 7 AM EST Friday for VTZ003-004-
006>008-010-012.
Wind Advisory from 7 AM Friday to 10 AM EST Saturday for
VTZ003-004-006>008-010-012.
NY...Winter Weather Advisory until 7 AM EST Friday for NYZ026-027-
087.
Wind Advisory from 7 AM Friday to 10 AM EST Saturday for
NYZ026-027-029>031-034-087.
&&
$$
SYNOPSIS...Taber
NEAR TERM...Evenson/Taber
SHORT TERM...Hastings
LONG TERM...Hastings
AVIATION...Evenson/LaRocca
Area Forecast Discussion
National Weather Service Caribou ME
1102 PM EST Thu Feb 7 2019
.SYNOPSIS...
A large area of low pressure will track from the Great Lakes
northeast into western Quebec tonight then into central Quebec
on Friday. High pressure will build in from the west Saturday
into Sunday.
&&
.NEAR TERM /THROUGH FRIDAY/...
1045 PM Update...
Adjusted the hrly temps/dewpoints to fit the latest obs.
Overnight temps look like they will hold in the 20s across the
northern 1/2 of the CWA while 30s will hold further south. Light
snow was occurring across far northern areas but there are
signs that light snow is beginning to transition to a period of
light sleet or even freezing drizzle. The latest RAP and LAPS
sounding show warm layer aloft w/the potential for freezing rain
overnight w/some icing, even as far south of Lincoln and
Bangor. Icing potential across the Bangor and Downeast region
will be short lived as warmer pushes in from the Gulf of Maine.
Sfc analysis showed high pres to the ne wedging down into Maine
while low pres lifts up across central Canada. This setup is
good for a freezing rain scenario w/an icing threat. Given the
latest setup, temps might struggle to warm above 32F Thursday
morning w/icing being prolonged especially across the Crown of
Maine. Therefore, ice accumulation could easily hit one tenth of
an inch.
Stayed close to the latest setup w/light snow going to a period
of sleet and then freezing rain across the northern and Central
Maine Highlands, while Bangor and Downeast should transition to
rain by daybreak.
Previous Discussion...
A very large area of low pressure lifting up to our west
tonight will pull deep moisture back over the region. High
pressure over the Maritimes combined with a weak triple point
low moving into the Gulf of Maine will hold cold air onto the
surface as precipitation moves in overnight. A mix of light
sleet and freezing rain is expected, with boundary layer
temperatures warming from south to north overnight. By dawn
Friday morning a bit of freezing rain will persist in far
northern Maine while plain light rain and some fog will cover
the rest of the area to the south. The freezing rain will likely
make mostly untreated surfaces, especially driveways, cars and
walkways icy. The precipitation will slide east into the
Maritimes Friday as the occlusion pushes east. A corridor of dry
air will push into the area during the midday and afternoon
Friday. This will bring a partly sunny and mild early afternoon
before cooler air starts pushing in from the west on gusty
westerly winds.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
Fropa occurs late Fri aftn with very steep low-lvl lapse rates
resulting in mixing up to nr H8 Fri night. Advisory level wind gusts
look to be a pretty sure bet drg this timeframe. Highs on Sat wl be
significantly colder than Fri on the order of 25-30 degrees.
May see isold snow showers in upslope areas Fri night into Sat as
wnw flow conts. Possibility exists for streamers coming off of the
St. Lawrence thru the weekend.
Pressure gradient wl gradually weaken on Sunday with wnw still rmng
gusty but significantly less than earlier in the pd. Temps wl be
warmer than Sat but still much blo normal even under full sun.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
High pressure builds offshore of the Delmarva on Wed with
another hipres center builds in fm Canada on Monday. GFS
bringing upr lvl low into Quebec on Mon with isold-sctd pops
mainly ovr Downeast drg the day while EC and CMC much further
east and weaker with upr system. For the time being hv gone with
a dry fcst for early in the week. Regarding the mid-week system
pcpn is fcst to mv into swrn Maine Tue night as light snow. EC
and GFS are both indicating a double-barrel low structure on Wed
but are having a hard time with the interaction btwn the nrn
and srn streams this far out.
&&
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: IFR to LIFR conditions in low clouds are expected
tonight into Friday morning. Conditions should improve to MVFR
late Friday morning, then VFR Friday afternoon. Gusty winds
following the passage of an occlusion may result in turbulance
Friday afternoon.
SHORT TERM: VFR through the end of the period at all terminals.
MVFR restrictions possible over the far north Fri and Sat in low
stratus.
&&
.MARINE...
NEAR TERM: Winds will increase to SCA tonight then remain SCA
much of Friday. Increasing westerly winds will begin to approach
gale late in the day on Friday.
SHORT TERM: Gale warning in effect Fri night into Sat night.
Winds diminish to SCA conditions through Mon night.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory until 10 AM EST Friday for MEZ001>004.
Winter Weather Advisory until 8 AM EST Friday for MEZ005-006-
010-011-031-032.
Winter Weather Advisory until 6 AM EST Friday for MEZ015>017.
MARINE...Gale Warning from 5 PM Friday to 7 PM EST Saturday for
ANZ050>052.
&&
$$
Near Term...Hewitt
Short Term...
Long Term...
Aviation...Hewitt/
Marine...Hewitt/
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
654 PM EST Thu Feb 7 2019
.AVIATION...
VLIFR fog aggressively set in late this afternoon as warmth and
humidity was drawn over the shallow surface based cold layer.
Impressive surface warm front for beginning of February with DUH and
TOL reporting 55/55. This fog will last for another couple of hours
before post-cold front mixing scours out surface layer moisture.
Convective fine line exists along the surface cold front that is
steadily marching into central Lower Michigan. Timing of the cold
front has the feature at the western edge of the CWA around 00-01Z
and through the far eastern cwa sometime around 03Z. Organization of
the cold front is interesting with a couple of dominant channels in
KGRR 0.5 reflectivity. The channels signify there are no stability
concerns immediately behind the front and low to midlevel subsidence
will be unimpeded in its descent to the surface. Best potential for
strongest SW wind gusts of 45 knots will exist south of I 94 with
frontal passage. The front has surged through TTF and JXN so it
appears set to make it through I 94. 900-800mb cold advection will be
lagged by a few hours. As as result, mixing depths will increase
during the course of the evening and expect winds to steadily
increase with this cold air. Most likely area to experience highest
wind gusts later on will be north of I 69 between 03-06Z. Cigs should
quickly improve this evening predominate MVFR conditions. Lake
effect snow shower potential will then increase after 10Z with a
decent signal for supersaturation with respect to ice through the -
10 to -15C window. There will likely be a diurnal component to lake
effect by midday.
For DTW...Warm front will surge through DTW momentarily which may
provide a relief from dense fog. Otherwise, strong surface cold
front to blast through at 02Z, which will bring SW winds,
potentially in the 38 to 43 knot range. Strong SW winds to continue
tonight. Low confidence exists in lake effect snow potential
beginning 17Z Friday.
.DTW THRESHOLD PROBABILITIES...
* High for cigs below 5kft through the TAF period.
* High for ptype of rain this afternoon and early evening.
* High for cigs 200 ft or less and/or visibility 1/2 SM or less
until approximately 02z.
* Low in thunderstorm occurrence and timing 23z-02z.
&&
.PREV DISCUSSION...
Issued at 354 PM EST Thu Feb 7 2019
DISCUSSION...
Deepening phase of a particularly dynamic cyclone is underway with
system-relative pressure falls of 4mb in the last 3 hours as the
surface low moves over Chicago at press time. Latest mesoanalysis
indicates a 140-155 kt upper jet in the lee of the approaching
trough anchoring a mature jet-front system that extends to the
surface where it is defined by a razor sharp baroclinic zone. Fast
propagation of gravity waves on Ch 2 is a testament to intense upper-
level shear with looping offering a pristine look into the
bifurcating warm conveyor beneath a stout descending dry airstream.
Another testament to the strong dynamic response is the emergence of
a lead PV anomaly adjacent and parallel to the cyclonic side of the
upper jet. These features are result of fgen processes taking place
at jet level, and the forcing is usually apparent in modeling in the
form of lower stratospheric (e.g. 200mb) frontolysis where the
descending branch of the thermal circulation can be seen drawing
higher PV air downward in advance of the parent PV feature over the
Upper Midwest.
Dry intrusion has scoured out meaningful precipitation in the winter
wx advisory, which will be cancelled. Lingering freezing drizzle
will end with temperatures at 32 and rising. In the meantime, the
CWA will remain socked in north of the warm front with widespread
fog which has been locally quite dense at times per reports in the
Novi area earlier today. The upstream cold front will sweep through
the CWA between 00-02z, by which time the surface low is progged to
be invof the Straits and deeper by another 8mb. The expansive
momentum field around the deepening surface low is forecast to have
no issue being forced groundward as 850mb temperatures plummet by
20C in the 6 hours following fropa and another 10C in the following
12 hours. The net change of -30C or more will support persistent
strong isentropic descent that will continue well into Friday,
slowly diminishing in intensity as the low pulls away during the
morning. Wind gusts around 45 mph are a foregone conclusion at this
point, and the wind advisory has been extended to the southern
border.
There are two pressing questions with regard to wind potential in
the near term, both revolving around the frontal passage itself. The
first is the extent to which the warm front is forced north into the
CWA given the resident extremely stable airmass. Cross-sections
indicate a rather gentle top-down transition to the incoming airmass
north of the warm front while any locations in the warm sector will
be exposed to a very dynamic surface front. Unstable mixing within
the elevated nose of the surface front will be capable of causing a
very transient higher end pop of wind upon its arrival. Fortunately,
limitations in available momentum in the lowest couple thousand feet
will likely cap potential at around 50 mph. The 18z NAM has made a
move toward the more aggressive HRRR depictions which indicate the
warm sector reaching the M59 corridor between 00-02z, which is
reasonable. M-59 south is therefore the corridor within which a
brief higher end gust potential will exist during fropa. The second
issue is potential for low-topped convection. Deeper convective
mixing would yield a low end severe threat. However, convection has
been observed to struggle along the front this afternoon and with
strongest dynamics rapidly shifting north, strongly suspect that
convection will not be an issue. Confidence is further increased by
low inversion heights to begin with.
Finally, the wind advisory has been extended to 15z Friday morning.
The 09-15z period will feature a waning gradient, but developing
instability, especially after sunrise, will likely force the
regional boundary layer into the typical large eddy outcome.
Resultant HCRs, aided by Lake Michigan influence, will carry the
potential to produce localized gusts reaching or nearly reaching
wind advisory criteria through at least mid-morning. Though the
dynamic support will continue through Friday, the diminishing
gradient will cap wind gust potential below advisory level by late
Friday morning. Wind chills will fall below zero by sunrise Friday
where they will stay as temperatures plummet from the 40s today to
near 10 by Friday evening. Modest overlake instability and poor
convective depths will support scattered to numerous snow showers
and flurries through the day Friday with little to no accumulation
expected.
Extended...Return flow from a departing high pressure system
centered across the western Atlantic to allow temperatures to slowly
rebound back back into the upper-20s for a high Sunday and back into
the lower- 30s Monday across the Metro area. Cooler conditions will
hold in place across the Tri-Cities into the Thumb with daytime highs
in the mid-20s. Weak frontogenetic forcing in the low to mid-levels
coupled with right entrance jet streak dynamics and the quick passage
of a weak shortwave will provide the likely chance for snow Sunday
night into early Monday morning. Roughly an inch of snowfall
accumulation is expected across SE MI with the passage of the
shortwave. Otherwise, a Canadian high pressure system will overspread
the northern Great Lakes Monday afternoon into the evening and will
act to diminish snow chances as the shortwave moves east into New
England.
A strong PV anomaly preceding a surface low will cross the Plains
and travel east into the Great Lakes Tuesday into Wednesday and will
bring the next likely chance for precipitation. This upper-level IPV
anomaly will travel over a region a strong baroclinicity across the
Plains and will help reinforce and strengthen low-level circulation.
Long-range models still have not converged on timing of
precipitation, but the Tuesday morning into Tuesday night timeframe
looks good to see the bulk of precipitation. Internal top-down
methodology still consistent will ptypes, starting all precipitation
as snow in the morning before transitioning over to a rain/snow to
rain solution by the afternoon as a nose of above freezing air
enters in the low-levels ahead of the low. A cold front is then
expected to sweep across Michigan as the low travels northeast into
Ontario, which will act to bring the chance for lake effect snow
throughout Wednesday as well as gusty conditions. High pressure to
then build in across the Plains into the Great Lakes which will act
to diminish snow chances after Wednesday.
MARINE...
Rapidly deepening low pressure will lift into northern Lake Huron
this evening. As the pressure gradient tightens this afternoon and
early evening, easterly winds will veer to southerly and increase to
25 kt. The low will drive a strong cold front through the area this
evening, turning winds to the west-southwest. Strong cold advection
will allow gale force gusts to mix down into all marine zones with a
low chance for gusts to storm force briefly possible with frontal
passage in the 00-06z time frame. Waves will build to over 10 ft
over the northern and central Lake Huron basin by Friday morning
with heavy freezing spray expected. Westerly gales will persist
through the day Friday with continuing cold advection before
gradually weakening below gale strength Friday night. High pressure
will build into the region from the northwest on Saturday into
Sunday, relaxing winds and wave action.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Wind Advisory until 10 AM EST Friday for MIZ047>049-053>055-060>063-
068>070-075-076-082-083.
Lake Huron...Heavy Freezing Spray Warning from 1 AM Friday to 4 AM EST Saturday
for LHZ361>363-462>464.
Gale Warning until 7 PM EST Friday for LHZ363-421-422-441>443-
462>464.
Gale Warning until 4 AM EST Saturday for LHZ361-362.
Lake St Clair...Gale Warning until 7 PM EST Friday for LCZ460.
Michigan waters of Lake Erie...Gale Warning until 7 PM EST Friday for LEZ444.
Low Water Advisory until 4 PM EST Saturday for LEZ444.
&&
$$
AVIATION.....CB
DISCUSSION...JVC/AM
MARINE.......TF
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Hastings NE
723 PM CST Thu Feb 7 2019
.UPDATE...
Issued at 722 PM CST Thu Feb 7 2019
Made another update tonight to decrease wind a bit faster, as the
surface high influence is taking hold.
UPDATE Issued at 703 PM CST Thu Feb 7 2019
Updated the forecast for tonight to increase dewpoints by several
degrees, based closer to the HRRR solutions.
&&
.SHORT TERM...(This evening through Friday)
Issued at 317 PM CST Thu Feb 7 2019
Snow has ended across the area and there are a few cold air
stratocumulus that continue to move through the area. Temperatures
have warmed a few degrees warmer than forecast, but that is still
cold.
As the sun goes down this evening, the stratocumulus are expected to
dissipate and skies will become clear. The surface high continues to
nose into the area tonight and as it moves through the winds should
diminish. That will be a good and a bad thing. On the good side, the
winds will keep the temperatures from falling off as far as they
could, but the bad part is that the winds combined with the cold
temperatures will create bitter cold wind chills. Have kept the wind
chill advisory as is for now. A few of the locations may not have as
cold of a wind chill, but it is still going to feel bitterly cold
out there.
By Friday morning, the wind will be fairly light and wind chills
will start to improve during the morning hours. During the
afternoon, there will be some warm advection, especially in the
west, and temperatures should warm up fairly quickly. Everywhere
will have some warmer temperatures, but the west will see the
greatest change. The pressure gradient tightens up on Friday, but
winds are not expected to get too breezy during the afternoon.
.LONG TERM...(Friday night through Thursday)
Issued at 317 PM CST Thu Feb 7 2019
Friday night the pressure gradient continues to tighten and the
winds aloft also increase. This will allow the winds to increase
during the night, but will still just be a little breezy. By
Saturday morning winds at 850mb are 50 to 60 knots. The winds will
be a little more breezy during the day. Will need to watch to see if
they need to be increased any as the time gets closer. This is
another case of good and bad. The winds will help to warm the
temperatures and the highs on Saturday will be around normal for
this time of year, but with the wind, it will not feel the best.
The next upper level wave and cold front will move through the area
late Saturday night into Sunday. Clouds will increase Saturday night
and there is a small chance for some light snow overnight Saturday
night. The best chance for snow will be Sunday morning as the upper
wave moves through. There is a good chance for snow, but amounts are
expected to be pretty light. The northern part of the forecast area
will have the best chance and there will be little to none in north
central Kansas.
There should be a little break Sunday afternoon and evening, but
another system starts to affect the area Sunday night into Monday
night. The temperatures are not as cold as we have been having and
so there comes the rain/snow concerns. Most of the area will have
only snow, but there could be a mix in the south as the temperatures
warm a little on Monday.
Tuesday through Thursday is expected to be a dry period.
Temperatures will be on the cool side, but still warmer than
currently.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday)
Issued at 550 PM CST Thu Feb 7 2019
VFR conditions are expected. Winds will continue to decrease as a
surface high approaches.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...Wind Chill Advisory until noon CST Friday for NEZ039>041-046>049-
060>064-072>077-082>087.
KS...None.
&&
$$
UPDATE...Heinlein
SHORT TERM...JCB
LONG TERM...JCB
AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Grand Rapids MI
656 PM EST Thu Feb 7 2019
LATEST UPDATE...
Aviation
.SYNOPSIS...
Issued at 330 PM EST Thu Feb 7 2019
-Additional power outages tonight into Friday from high winds
gusting to 45 mph; falling ice/tree branch concerns
-Standing water freezing abruptly tonight (flash freeze)
-Snow showers, poor travel conditions overnight through Friday
-Lengthy power outages possible as very cold air, gusty winds, and
snow showers hamper recovery efforts on Friday
-Risk for ice jams and localized flooding continues
&&
.DISCUSSION...(This evening through next Thursday)
Issued at 330 PM EST Thu Feb 7 2019
Kent, Ionia, and Montcalm counties have been hardest hit by ice
as this is where the two freezing rain events overlapped (Tuesday
night`s event which never melted off and this mornings). Well
over 100,000 customers are without power and this number may grow
as the winds pick up considerably with the passage of the cold
front early this evening.
Still some uncertainly if we get enough warmth in the
aforementioned hard hit area to melt off all the ice before the
winds hit. Latest guidance suggests this area will get to about 40
degrees for a few hours late this afternoon and early evening.
We also have the hazard of chunks of ice falling onto cars or
pedestrians when temps are warming late this afternoon. Falling
tree branches possibly become a hazard as well as the winds begin
gusting to 45 mph this evening.
Areas north/northeast of Grand Rapids such as Big Rapids, Mt
Pleasant, Alma, Clare have newly accumulated ice from this event
and have less chance of turning mild enough long enough to have
much melting. Therefore the areal extent of the power outages
will probably grow/expand north and eastward when the strong
winds hit this evening.
Timing-wise...areas of dense fog/light rain for the next few
hours as the deepening sfc low tracks overhead. The fog threat
ends once the strong wind gusts commence around 5-6 PM in far sw
Lwr MI per the HRRR then spread north and east across the rest of
the area through 8-9 PM. Frequent gusts of 35-40 mph from the
west will be common tonight, but a few 45-50 mph gusts may occur.
As far as the flash freeze, it is between 10 PM and 1 AM tonight
that the rush of cold air sweeps in from the west and sends temps
down into the teens rather abruptly. The onset of the snow showers
should coincide with the Arctic intrusion.
While some briefly intense snow showers are possible overnight
into Friday, total accumulations through Friday evening should be
held down in the 1-3" category. The strong winds typically makes
it difficult to focus heavier snows in a particular location for
any length of time, and the bands will extend well inland across
the entire state. The highest total amounts should be displaced
inland, probably near the Hwy 131 corridor, due to speed
convergence - with lesser amounts at the coast.
Quiet weather will aid power recovery efforts on Saturday with a
1045mb sfc high overhead. Then a prolonged light snow event
appears possible Sunday afternoon and night, although with limited
impacts. A more impactful system is possible on Tuesday into
Wednesday as another sfc low/occlusion sends more snow and/or
mixed precipitation into the area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 656 PM EST Thu Feb 7 2019
West winds will gust over 30 knots at times through Friday with
some gusts over 40 knots possible tonight. There will be areas of
IFR conditions through tonight with rain showers transitioning to
snow showers overnight. Lake effect snow showers will continue to
bring IFR conditions Friday morning into Friday afternoon
especially across western Lower Michigan from MKG to GRR.
&&
.HYDROLOGY...
Issued at 330 PM EST Thu Feb 7 2019
A very active hydrologic situation continues to unfold across West
Michigan with snowmelt runoff combining with ice in the rivers and
precipitation events to increase the threat of flooding.
Strong rises continued on most of the rivers across the region as
snowmelt continues to funnel from the smaller streams into the
larger rivers. Many of the small streams are approaching or just
past their crests, while the larger rivers will keep rising for
several more days. Although widespread flooding is not expected,
local flooding is still a concern, as ice in the rivers complicates
river flows.
Several small ice jams have formed around the area, though only
minor flooding is currently occurring. A more significant ice jam
continues on the Grand River at Portland, resulting in residential
flooding. A flood warning remains in effect for the Grand River at
Portland.
Additional precipitation events are likely over the next week. Given
that ice is currently in many rivers, those with interests along
area rivers should continue to monitor the situation as rapid
changes may occur.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 7 PM EST Friday for MIZ037>040-
043>046-050>052-056>059-064>067-071>074.
&&
$$
SYNOPSIS...Meade
DISCUSSION...Meade
AVIATION...Ostuno
HYDROLOGY...63
Area Forecast Discussion
National Weather Service Indianapolis IN
1015 PM EST Thu Feb 7 2019
.UPDATE...
The Near Term and Aviation sections have been updated below.
&&
.SYNOPSIS...
Issued at 205 PM EST Thu Feb 7 2019
Strong low pressure over Illinois is expected push to the Great
lakes this afternoon and drag a cold front across central Indiana
by early evening. Rain showers along with a few thunderstorms are
expected to continue this afternoon along and ahead of the front.
Cold Canadian high pressure is expected to build across Indiana
tonight and Friday in the wake of the front. This will bring dry
weather along with much colder temperatures for the first part of
the weekend.
A warm front will return to Central Indiana late on
Sunday...bringing precipitation chances back to the state on
Sunday afternoon. Precipitation chances are expected to linger
across the state through at least Tuesday as the frontal boundary
lingers near the area and another low pressure system is expected
to arrive from the southwest.
&&
.NEAR TERM /Tonight/...
Issued at 1010 PM EST Thu Feb 7 2019
Going forecast is in fairly good shape. Per latest HRRR and LAMP
hourly numerical guidance, and obs trends, there is a decent
chance that we may see the single digits in the northwest by
morning, and made some downward adjustment to mins in that portion
of the forecast area. Additionally, added a chance of flurries
overnight per upstream obs and radar trends. These should be of
little significance or impact. Adjusted sky grids closer to
satellite trends as well.
Decided to go ahead and cancel the flood watch a little early as
flooding is ongoing and precipitation has ended across the area.
Flooding will continue to be handled with areal and river flood
warnings and statements throughout the night and beyond as needed.
Will keep the wind advisory going although gusts thus far are
largely just below criteria. Cannot rule out a few 45 MPH gusts
before all is said and done.
Previous discussion follows.
Issued at 205 PM EST Thu Feb 7 2019
Surface analysis early this afternoon shows low pressure in place
across northern Illinois...along with a cold front stretching
southward to southern Illinois and eastern Arkansas. Radar shows
abundant rain showers across southern Central Indiana with a line
of embedded thunderstorms pushing across the southern forecast
area. GOES16 shows a stream of tropical moisture pushing
northeast across Arkansas to Indiana and Ohio. Heavy rains were
resulting in flooding across Central Indiana. Will continue high
pops and the flood watch through the afternoon hours as rain and
flooding is expected to be ongoing for several more hours.
The GFS and NAM suggest the surface front will be east of Central
Indiana by 00Z. This should bring a quick end to all of the
ongoing precipitation. Forecast soundings and time heights show
plentiful dry air arriving this evening and overnight with
subsidence within the column. Thus will trend toward a dry
forecast overnight...along with decreasing clouds by morning.
Strong cold air advection is expected within the wake of the front
as the models suggest 850mb temps falling toward -13C by 12Z.
Furthermore a strong lower level pressure gradient is expected
overnight and this along with the cold front will result in sub
zero wind chills on Friday morning. However at this time values do
not appear high enough to suggest an advisory will be needed.
Given the cold air advection will trend lows at or below the
forecast builder blends.
&&
.SHORT TERM /Friday through Sunday/...
Issued at 205 PM EST Thu Feb 7 2019
Dry and cold weather is expected on Friday. this will persist
through at least Sunday morning when a warm front arrives from
southern Central Indiana. Forecast soundings and Time heights show
a very dry column across Central Indiana on Friday through
Saturday Night along with good subsidence. This will be due to a
few features...namely the weak upper ridging that will be
established over the weekend over the plains states...resulting
in strong lee side subsidence and a strong associated surface High
pressure system. With unreachable convective temperatures along
with anti-cyclonic lower level flow in place...only partly cloudy
skies will be expected from some passing high cirrus. Thus will
use a partly cloud sky and dry weather through Saturday night.
Given the cold air mass will trend temperatures at or below the
forecast builder blends.
By Sunday the strong high pressure system will have drifted east
of Indiana and a more zonal flow will be in place aloft. This will
result in the beginning of a more southerly surface
flow...allowing moisture o return . The GFS shows a short wave
passing through the Ohio valley on Sunday as a surface warm
frontal boundary sets up amid the return flow from the departing
high. These features should be enough to allow a return of pops to
the forecast. Forecast soundings suggest precipitation should
begin as snow on Sunday as the forecast soundings appear saturated
and below freezing during the afternoon and evening. At the
moment...some light accumulations appear possible given the
expected cold ground. Will trend pops higher and high temps on
Sunday cooler than the blends.
&&
.LONG TERM /Sunday night through Thursday/...
Issued at 316 PM EST Thu Feb 7 2019
More seasonable conditions will be in place for the long term.
Brief upper ridging will move through, but at the same time a
front will approach from the south. Best chances for precipitation
will move in from the south. Better upper forcing will move in by
Monday night. Temperatures will be running near to below normal
(with the exception of Tuesday highs which will be a bit warmer)
and so these precip chances will be in the form of snow at night,
with a rain/snow mix possible at times during the day, changing
over to rain on Tuesday. By Tuesday afternoon dry weather could
move in, but the pattern is looking fairly progressive so other
small upper waves could bring more chances in as we get closer.
&&
.AVIATION /Discussion for the 08/03Z TAF update/...
Issued at 1010 PM EST Thu Feb 7 2019
TAFs are in very good shape. Minor adjustments made to bring a
couple of the sites closer in line to obs, but general forecasts
in excellent shape. Previous discussion follows.
Issued at 630 PM EST Thu Feb 7 2019
Predominantly MVFR conditions during the first 5-9 hours of the
period, with VFR conditions returning thereafter.
A strong cold front has swept through the sites, and with it,
precipitation is coming to an end and IFR ceilings will soon move
out where they haven`t already. MVFR ceilings will dominate
through the evening and into the overnight, before improving late
as the clearing line approaches.
Winds will be a significant impact much of this period. Winds will
generally be from 270-290 degrees. Sustained winds early in the
period will be as high as 20-25KT at times with gusts as high as
30-35KT. These sustained winds and gusts will gradually weaken
slightly later tonight into Friday, although winds will remain
gusty throughout the period.
Visibilities should become unrestricted quickly and remain so
throughout the period.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 7 AM EST Friday for INZ021-028>031-035>049-
051>057-062>065-070>072.
&&
$$
SYNOPSIS...Puma
NEAR TERM...Puma/Nield
SHORT TERM...Puma
LONG TERM...CP
AVIATION...Nield
Area Forecast Discussion
National Weather Service Louisville KY
934 PM EST Thu Feb 7 2019
.Forecast Update...
Issued at 934 PM EST Thu Feb 7 2019
Went ahead and cancelled the NW portions of both the Flood Watch and
the Wind Advisory. It has stopped raining along and north of a
Morgantown to Elizabethtown to New Castle, KY line so there is no
longer a need for the Flood Watch. That being said, a few areas of
standing water near low water crossings will likely hang around into
the overnight. Use caution if traveling and never drive into water!
Otherwise, will leave the Flood Watch going where it is still
raining for another 3 to 4 hours. Also let the Wind Advisory go for
areas along and north of that same line as gusts are mostly letting
up a little 2 to 3 hours after frontal passage. There could still be
some gusts up around 35 mph at times for the next several hours, but
overall the threat for gusts over 40 mph is quickly diminishing.
Again, will leave the rest of the Wind Advisory alone for another
few hours.
Wanted to address the other concern about lingering wet roads
freezing as temps drop into the teens and 20s by dawn. Was watching
a web cam up near Huntingburg, IN all evening and noted that it took
about 2-3 hours after the rain to stop for the wind to completely
dry the pavement. So, think that the threat for lingering slick
spots should be pretty limited due to the wind and dry air making
pretty quick work of damp roadways. The only real concern is with
any standing puddles that could be a little tougher to eradicate
before it freezes. For now, will remain vigilant but not overly
concerned with the threat for slick spots by dawn. Nevertheless,
folks should use some caution for the morning commute.
Previous Update...
Issued at 746 PM EST Thu Feb 7 2019
The strong cold front has pushed east of the I-65 corridor and we
are seeing a 10-15 degree drop in about 15-20 minutes behind it. In
addition, winds are gusting in the 35-45 mph range behind the front,
with SDF clocking a peak wind of 44 mph a bit ago. Will keep the
Wind Advisory going through the evening hours to get the front
through the area.
Widespread light to occasionally moderate rain also continues along
and behind the front, however this is also pushing slowly east with
time. Overall, expect about a 3-4 hour lag between frontal passage
and the end of the light rain. Very sharp temp gradient exists as
the Lake Cumberland area remains in the low 70s, while Huntingburg
has found it`s way into the upper 30s! Could still see some flakes
flying on the back side of the precipitation shield, but no accums
expected as surface temps will likely lag behind air temps due to
the recent mild stretch of weather. Also not overly concerned about
slick spots on roadways toward dawn as a several hour stretch of
gusty and dry conditions should work to dry surfaces before temps
really plummet below freezing. Suppose a few slick spots could be
around where water has puddled, but don`t expect it to be an issue.
Still monitoring some of the areas up in southern IN that had Flood
Advisories and Warnings from earlier. Rain has stopped and will be
calling shortly to see if problems have subsided to let the
advisories/warnings go. Will also be continuing to keep an eye on
area rivers as they continue to rise.
Finally, did have to issue a Special Weather Statement for a thin
line of convection down near Lake Cumberland where the slightest of
instability gradients still exists ahead of the cold front. Seeing
some pretty good rainfall rates down there, albeit brief. This could
cause ponding of water on roadways and minor nuisance flooding, but
should be too short-lived for any advisory or warning product. Will
keep an eye on these cells over the next half hour to 1 hour.
Overall, everything looks on track and will be looking for
opportunities late this evening to dial back advisories and
headlines as things wind down. Goodbye mild weather...it was a nice
run!
&&
.Short Term...(This evening through Friday)
Issued at 250 PM EST Thu Feb 7 2019
Watching for stronger storms this afternoon and evening, then much
colder air will move into the region to close the work week. Line of
storms that formed earlier is in the process of weakening.
Noteworthy however is the lack of leading stratiform ahead of it as
well as the warm air it is moving into. We have had some record
highs ahead of this line. Consequently, we are seeing model forecast
soundings show a narrow line of surface-based CAPE as well as plenty
of shear. Still think we could see either new development, in the
form of spinning low-topped showers or perhaps a reinvigoration of
the line, as per the 12Z NamNEST solution or 16Z HRRR run, mainly
south of I-64 and east of current convective line.
Outside of that severe weather threat, we are seeing winds gusting
in the 30-45 mph range. We likely will see this continue for a few
hours behind the frontal passage tonight. Not planning any changes
to the current wind advisory.
Cold air will blast into the area overnight, with lows crashing into
the low to mid 20s for many locations, probably even the teens in
southern IN. Highs Friday, likely under good insolation, should stay
in the 25-30 degree range for southern Indiana and 28-33 for many
parts of central Kentucky.
.Long Term...(Friday night through Thursday)
Issued at 301 PM EST Thu Feb 7 2019
...ACTIVE WEATHER PATTERN EXPECTED DURING THE FIRST HALF OF NEXT
WEEK WITH ADDITIONAL FLOODING POSSIBLE...
===================================
Friday Night through Saturday Night
===================================
Surface high pressure is forecast to build into the region Friday
evening and into the day on Saturday. Combination of clear skies
and light winds will result in a decent radiational cooling event.
Lows Saturday morning should drop into the 10-15 degree range over
southern Indiana and the northern half of KY. Across southern KY,
lows of 15-19 are expected. High pressure will result in mainly
sunny skies on Saturday but temperatures will remain cold. Highs of
35-40 look likely across the region. By Saturday night, we`ll see
winds shift from the east to the southeast and low-level isentropic
lift will likely get underway. Cloud cover is likely to increase
throughout the night and temperatures are not expected to drop as
much. Current data suggests that lows in the 20-25 degree range are
likely by sunrise Sunday.
===================================
Sunday through Thursday
===================================
Moving along into Sunday, the next weather system will make a move
toward the Ohio Valley Sunday morning. Overall trend in the models
is for precipitation to break out across the region from southwest
to northeast by mid-late morning. This is a little slower than in
previous model runs. Low-level temps may be marginally cold enough
initially to support a wintry mix, but as low-level warm air
advection scheme becomes increasingly stronger, temps will warm by
early afternoon resulting in plain rain. Highs Sunday afternoon
will likely warm into the upper 30s to the lower 40s. A few upper
40s will be possible along the KY/TN border region. Combination of
strong isentropic upglide along with a persistent fetch of Gulf
moisture should keep widespread rainfall in place across the region
Sunday night. Temps may cool into the mid 30s by early Monday
morning, but model proximity soundings suggest that rain will be the
dominant precipitation type. However, there is a chance that some
low-level cold air may work into our northern row of southern IN
counties resulting in a mix or change over to some snow.
For Monday and Tuesday, overall upper air pattern looks to take on a
similar setup to what we saw late last week with a persistent
southwest flow aloft with much of the Ohio Valley located in a broad
baroclinic zone. Southern IN and central KY are likely to remain
within the warm sector of the zone resulting in additional rainfall.
Several perturbations will move through the region bringing periods
of moderate to occasionally heavy rainfall. Rainfall amounts of 1-3
inches look likely with localized higher amounts possible. Given
saturated soil conditions, this will lead to additional localized
flooding issues in some areas. The larger story would be that this
additional runoff would go right into our rivers which will simply
result in a longer period of flooding with some rivers seeing
additional rises into higher flood categories. Highs Monday look to
warm into the mid-upper 40 across southern IN and northern KY while
southern KY sees temps in the lower 50s. Most locations should warm
into the 50s/60s on Tuesday when the warm advection scheme is
maximized.
By Wednesday, surface frontal boundary looks to shunt eastward
taking the rainfall away from the region. A cooler airmass will
work back into the region with dry conditions expected through
Thursday. Highs on Wednesday look to range from 40-45 across the
north with mid-upper 40s across the south. Slightly warmer readings
are expected on Thursday. Overnight lows through the period will be
in the upper 20s to the lower 30s.
&&
.Aviation...(00Z TAF Issuance)
Updated at 647 PM EST Thu Feb 7 2019
A strong cold front is pushing through our area at this hour. It has
already passed HNB and will pass through SDF/BWG shortly after 7 PM
EST. LEX should expect passage around 9 or 10 PM EST. Expect winds
to shift to a WNW component around 20 mph and gusting up around 35
mph for a few hours after frontal passage. Gusty WNW winds will then
continue through much of the overnight, although slowly backing off
more in the 20-30 mph range for gusts.
In addition to the gusty winds, light to occasionally moderate rain
will continue at BWG/SDF/LEX for a few more hours. Expect the rain
to end at SDF/BWG around 10 or 11 PM EST, and LEX around 1 AM EST.
Low ceilings in the low MVFR range (below fuel alternate) will
settle in behind the frontal passage, with perhaps some brief IFR
also. Cold dry air quickly spills in behind the front and should
begin to scatter out the low level moisture before sunrise. This
will bring a return to VFR, but gusty W wind will continue around 20
mph through near the end of this cycle. Skies should be VFR for the
daylight hours of Friday.
&&
.Climate...
Issued at 245 PM EST Thu Feb 7 2019
Listed below are the record highs and forecasts for today.
Site Rec. (Yr) Fore.
SDF 69 (1925) 70**
LEX 67 (1925) 70**
BWG 71 (1931) 73**
FFT 69 (1925) 69**
**Record already broken or tied today.
Listed below are the record warm lows and forecasts/obs for
today. The caveat is that a cold front will move through before
midnight, likely pulling readings down below record levels. LEX
stands the best chance to break their record, should the timing
of the frontal passage slow down.
Site Rec. (Yr) Fore.
SDF 55 (2017*) 39
LEX 54 (2017) 43
BWG 52 (2017*) 35
FFT 56 (2017) 40
In addition to the warmth, a very moist airmass over the region
likely will bring record rainfall. Below are the record rainfall
amounts for today for each of our climate sites.
Site 2/7 Record (Year)
SDF 1.09" (1890)
LEX 1.30" (1890)
BWG 1.05" (1933)
FFT 0.87" (2018)
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...Flood Watch until 1 AM EST /midnight CST/ Friday for KYZ035>037-
039>043-045>049-053>057-062>067-070>078-081-082.
Wind Advisory until midnight EST /11 PM CST/ tonight for
KYZ035>037-039>043-045>049-053>057-062>067-070>078-081-082.
&&
$$
Update...BJS
Short Term...RJS
Long Term...MJ
Aviation...BJS
Climate...RJS
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Friday)
Issued at 240 PM CST Thu Feb 7 2019
Cold arctic air streams southward, bringing dangerously cold wind
chills tonight into Friday morning.
An elongated meridional high pressure ridge is building into the
region this afternoon, its arrival heralded by significant CAA on
a northwest wind of 15 to 25 kts, gusting to near 35 kts at times.
Differential CAA this afternoon mixed the boundary layer up to
around 1-km in depth and allowed for the development of shallow
HCR stratocumulus in the wake of last night`s system, but the lack
of deeper saturation at the top of the BL limited the production
of any precipitation. These winds will keep wind chill values in
the single digits below zero for the rest of the afternoon, with
winds and the stratocumulus lessening this evening as the surface
pressure gradient expands and diurnal boundary-layer decoupling
takes place.
The combination of the approaching 1043 mb high, lessening winds,
dewpoints in the single digits below zero, and (an albeit
shallow) snow/ice/sleet pack should facilitate the rapid fall of
temperatures tonight. Adjusted lows tonight towards the
Canadian/BC RAP solutions; the coldest of the guidance suite. This
pushes min temps to around the zero degree mark and wind chills
to -10 to -20; coldest along the Kansas/Nebraska border. The
surface ridge slides eastward during the day on Friday, but with
the H850 ridge not clearing the forecast area until after 00Z, any
meaningful WAA takes place after peak heating on Friday and highs
should be confined in the 20s.
.LONG TERM...(Friday night through Thursday)
Issued at 240 PM CST Thu Feb 7 2019
There are a couple of systems of note for the weekend and early
next week that could bring a wintry mix to the area.
Broad longwave troughing along the North American west coast re-
amplifies over the course of the weekend as a PV lobe ejects from
the Polar Vortex. A modest shortwave rounds the base of this
amplifying trough late Saturday into Sunday, with the main trough
ejecting eastward late Monday into Tuesday. Broad zonal flow then
sets in for midweek, though model diversity increases as this
pattern flattens out. These aforementioned waves will be the main
drivers for two periods of wintry precip early Sunday and again
Monday into Tuesday.
Lee cyclogenesis along the Front Range induces weak 280-290K
isentropic ascent over the forecast area late Saturday night into
Sunday morning. NAM/GFS bufr soundings do saturate at least the
lowest 1-2 km of the profile within this realm of ascent. GFS
profiles also saturate through the DGZ, at least for a short
while, whereas the NAM is devoid of moisture above -4 C. With
surface temperatures in the mid/upper 20s, freezing drizzle would
be the most likely precipitation type in the NAM scenario.
However, there remain uncertainties in the temporal juxtaposition
of the lift and saturation and have left a mixture of
snow/freezing drizzle in the official forecast.
The H500 wave outruns the surface cyclone and results in
cyclolysis Sunday afternoon. The baroclinic zone lifts back
northward on Monday as heights fall ahead of the next shortwave
in the train. Once again, there is a modest chance of a wintry mix
with this system, but confidence in this solution is lower than
average at the present time and refrained from specifying a
time/location of freezing precip with this forecast.
Temperatures for this entire forecast period will fluctuate
around or slightly below average for this time of year with the
baroclinic zone lingering near, but mainly south of the forecast
area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 506 PM CST Thu Feb 7 2019
Skies continue to clear into sunset with the parent storm system
continuing to move further out of the region. Cold air continues
to spill into the area, so will maintain some mixed BL with winds
around 10kts. Winds gradually veer more southerly by tomorrow
afternoon.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Wind Chill Advisory from 9 PM this evening to 8 AM CST Friday
for KSZ008>012.
&&
$$
SHORT TERM...Skow
LONG TERM...Skow
AVIATION...Drake