Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/29/19
AREA FORECAST DISCUSSION
National Weather Service Albany NY
959 PM EST Mon Jan 28 2019
.SYNOPSIS...
A storm system will approach the region tonight, allowing
clouds to increase overnight. This system will bring widespread
plowable snow to the region Tuesday through Tuesday night. An
arctic airmass arrives in the wake of the storm system,
resulting in dangerously cold temperatures Wednesday through
Friday.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Updated at 945 pm. Mainly clear skies with light winds have
allowed temperatures to fall quickly this evening, with readings
at 9 pm ranging from the single digits to near zero near and north
of Albany, to the teens in the mid-Hudson Valley. Clouds are
spreading eastward across central NY and will overspread our
area shortly after midnight with temperatures remaining steady
or slowly rising late tonight. A quick look at the latest HRRR
and 00z NAM forecasts indicate little change in the overall
thinking with our upcoming storm. Light snows are still expected
to reach areas of west of the Hudson Valley toward daybreak.
Light snow will persist into the afternoon across areas west of
the Hudson Valley and also in the upper Hudson Valley north of
the Capital District with downsloping southerly winds resulting
in just spotty flurries farther to the south. Steadier, heavier
snow will organize across the entire area by late afternoon as
a wave of low pressure moves north from the mid-Atlantic toward
southwest New England.
Watches will be converted to either warnings or advisories based
on additional incoming guidance expected through midnight. For
now there remains enough uncertainty on snowfall totals in the
Capital District so that watches will remain in effect until all
of the 00z guidance is in. Previous discussion is below...
Clouds increase tonight and the leading edge of light snow
should reach western areas by daybreak. The period of clear sky
and light winds this evening will allow temperatures to fall
into the single numbers to low to mid teens for lows, then
become steady and maybe rise a degree or two toward daybreak.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
Winter Storm Warning for the Southern Adirondacks, western
Mohawk Valley, and Lake George Saratoga Region and Southern
Vermont...
Winter Storm Watch is in effect for the Greater Capital
District, northern and central Taconics, mid-Hudson Valley
including eastern Green and western Columbia counties,
Washington county of eastern New York, as well as the Berkshires
of western Massachusetts...
The storm system that will be affecting us Tuesday through
Tuesday night is not a conventional snow storm. The leading edge
of the snow will reach the southern Adirondacks and eastern
Catskills first, late tonight, then spread across the rest of
the region around or just before daybreak through Tuesday
morning as low level jet convergence, warm advection and
isentropic lift increase. Upslope process will enhance snowfall
in the southern Adirondacks, northern edge of the western
Mohawk Valley and Lake George Saratoga Region. Downslope flow
could limit snowfall amounts in the Schoharie Valley, central
and Western Mohawk Valley, Capital District, and Hudson Valley.
There is considerable disagreement in liquid equivalent
precipitation forecasts from sources of guidance/ensembles with
some guidance that has shown considerable reliability in the
past showing liquid equivalent amounts limited to the point
that areas currently still under winter storm watches may not
reach 6 to 7 inches but other guidance suggests those amounts
even in valleys with slightly higher amounts in higher terrain.
There are also some indications in sources of guidance that
there will be a period Tuesday afternoon and evening that the
strongest vertical motion extends well through the dendritic
growth zone over eastern NY and western New England, which could
result in better snow ratios and convert to more snow regardless
of the relatively low liquid equivalent.
With all these conflicting factors, winter storm warning were
issued only in the areas of the highest confidence, in the areas
of upslope into higher terrain of the southern Adirondacks,
eastern catskills and southern VT. Watches were left up where
they existed already and can be converted to either advisories
or low end warnings based on the new set of guidance expected
tonight. The Poughkeepsie area to Litchfield Hills may get
advisory level snows and those headlines will be considered with
the latest guidance as well.
Climatological snow maps based on multiple storms with strong
southwest boundary layer flow suggest there could be quite
considerable differences in snow amounts in short distances
between valleys and terrain, which was also a factor in keeping
watches up where the confidence in reaching 6 to 7 inches was
lowest. The Helderbergs may get 7 or more inches while the
Capital region may see 4-7 inches. So, again, some of these
uncertainties should get cleared up overnight with the newest
guidance.
There may be a mix with rain in the Poughkeepsie area and
Litchfield Hills Tuesday afternoon as well before going to all
snow Tuesday night. Again, the complicated watches and warnings
and varying start and end times will be consolidated after the
latest guidance clears up the lingering uncertainties
overnight. Highs Tuesday in the 30s but some 20s northern areas.
Snow ends Tuesday night and an initial push of colder air
spreads into our region. A strong upper low and leading edge of
much colder air tracks through our region Wednesday with the
potential for snow showers and squalls on the leading edge of
the Arctic air. The low and midlevel lapse rates look quite
steep along the cold front. Highs Wednesday in the teens to
lower 20s but some mid 20s southern areas and some single
number northern areas.
Windy and cold Wednesday night with most areas at or below zero
and wind chill advisories and warnings may be needed with wind
chills less than 15 below and as cold as 30 to 40 below. Highs
Thursday in the single numbers to lower teens with continued
breezy conditions.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
The long term forecast period will begin with lingering lake effect
snow over the western Adirondacks and bitter cold temperatures over
the entire region. High pressure builds in for a portion of the
weekend before another low pressure system approaches from the Great
Lakes region late Sunday or early next week.
Thursday night through Friday...Lake effect snow over the
Adirondacks will begin to retract and diminish late Thursday through
Friday due to boundary layer flow becoming disrupted as a short wave
trough swings through the northern periphery of the region. Some
light snow accumulations of around an inch will be possible
overnight Thursday into Friday morning over Herkimer county.
Blustery conditions will continue Friday with 850-hPa temperatures
between -15 and -20 C. Wind chills will continue to be well below
zero in the negative teens and twenties. Wind chill headlines could
be needed to address these dangerously cold temperatures.
Saturday through Monday...Mid level ridging will build into the
region late Friday into Saturday with the associated subsidence
resulting in surface high pressure. Temperatures Saturday morning
will begin cold near zero and moderate into the teens and twenties
by Saturday afternoon with partly cloudy skies. Global guidance
suggests that a shortwave trough digs into the Midwest CONUS Sunday
into Monday with surface cyclogenesis commencing shortly after. The
surface low looks to develop over the Midwest with the warm front
extending to the east over the NE CONUS late Sunday into Monday.
This could result in precipitation beginning Sunday evening, but the
precipitation types are very much up in the air as of now. Guidance
suggests mostly rain for the region as of now but this will be
highly dependent on the track of the system and whether or not the
warm sector overspreads our region. Highs Sunday will be near normal
in the upper 20s and low 30s. Highs Monday will continue to moderate
into the upper 30s to low 40s.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
High pressure will dominate early in the TAF period, giving way
to an approaching low pressure system from the western Great
Lakes. VFR conditions are expected through at least 12Z Tuesday,
but clouds will thicken and lower throughout the night. Snow is
expected to begin over the TAF sites in the morning or early
afternoon. The timing and intensity of the snowfall is the main
challenge for this TAF issuance. Isentropic lift will bring snow
to the higher terrain beginning around 09Z Tuesday, but forecast
soundings suggest it will take longer to saturate over the TAF
sites. So we will mention VCSH beginning at 12Z with cigs/vsby
falling to MVFR by 15Z. It appears the heavier snow will occur
after this TAF period. The exception may be over KGFL which
could see IFR conditions by around 15Z in steadier snowfall.
Winds for the remainder of today will be generally from the
northeast at 5-12 kt with some gusts near 20 kt at KPOU
possible. Winds will become light and veer to southeasterly
early tonight, increasing to 5-10 kt late tonight into Wednesday
morning, with some gusts to 20 kt possible at KALB/KPSF. LLWS
conditions will be possible at KPOU/KGFL after around 09Z where
surface winds are expected to be lighter as 2kft AGL winds
increase to 30-35 kt from the south.
Outlook...
Tuesday Night: High Operational Impact. Definite SN.
Wednesday: Moderate Operational Impact. Breezy Chance of SHSN.
Wednesday Night: Low Operational Impact. Breezy NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: No Operational Impact. NO SIG WX.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.
&&
.HYDROLOGY...
The next chance for widespread precipitation arrives with a
strong storm system Tuesday into Wednesday. Precipitation will
be in the form of mostly snow, but may mix with rain in the mid-
Hudson valley into northwest Connecticut. Total QPF with this
storm looks to be around 0.5 to 0.75" with just over an inch
possible in the southern Adirondacks.
Water levels will slowly recede, but ice jams will continue to
freeze in place.
Lake effect snowfall will impact the western Adirondacks into
the Mohawk Valley Wednesday through Thursday night.
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...Winter Storm Warning from 1 AM Tuesday to 4 AM EST Wednesday
for NYZ032-033-038-039-041-042-058-063-082-083.
Winter Storm Watch from Tuesday afternoon through late Tuesday
night for NYZ043-053-054-060-061-084.
Winter Storm Watch from 5 AM EST Tuesday through late Tuesday
night for NYZ040-047>052-059.
MA...Winter Storm Watch from Tuesday afternoon through late Tuesday
night for MAZ001-025.
VT...Winter Storm Warning from 1 PM Tuesday to 7 AM EST Wednesday
for VTZ013>015.
&&
$$
SYNOPSIS...NAS
NEAR TERM...MSE/NAS
SHORT TERM...NAS
LONG TERM...Cebulko
AVIATION...Thompson
HYDROLOGY...NAS
Area Forecast Discussion
National Weather Service Boston/Norton MA
1053 PM EST Mon Jan 28 2019
.SYNOPSIS...
High pressure will bring dry and cold weather tonight as it
builds across New England and heads to the Maritimes. Low
pressure is expected to track across s New England Tuesday
night, bringing a mix of snow and rain to much of the area,
with the heaviest snow to the Berkshires and north central
Massachusetts. Bone chilling cold late week into the early
weekend, a mild pattern is forecast beginning Sunday into the
following week with chances of rain and/or snow.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
1015 PM Update...
Winds have shifted to N-NE along the immediate coast from about
Boston southward to Cape Cod and the islands over the last few
hours. Low ocean clouds have worked onshore from Cape Ann to
Cape Cod, even with light N winds across Essex county into
portions of central Merrimack River valley.
Previous forecast suggested that, with onshore winds, will see
ocean effect snow showers develop from about midnight onward,
mainly from Boston northward. However, still noting dewpoints in
the single digits from KBOS-KOWD north and west ward, but have
risen to the mid teens to around 20 across SE Mass, Cape Cod and
the islands. Even there, still noting T/Td spreads of around 10
degrees. Also noting no echoes reported on the TBOS 0.3 degree
radar reflectivity so far.
So, decided to back off on the ocean effect snow showers
mentioned in the previous forecast. Did keep snow flurries by
around 06Z near the immediate shoreline. Once winds veer to
E-NE near and N of Boston to the north shore, may start to see
spotty snow showers develop as the low level moisture
increases mainly around or after 09Z.
Remainder of the forecast was in good shape, but did update to
bring conditions current.
Previous Discussion...
Beneath the veil of high clouds per nighttime satellite micro-
physics, marine stratus clouds lurk. Decent low-level dry air,
absent outcomes per HRRR signaling a red flag, do not expect
much in the way of accumulation and little to no impact to
visibility.
Some impact to 2m temperatures with encroachment of low clouds
into E/SE MA along with onshore flow coupled with the mid to
upper level cloud shield courtesy of offshore synoptics
associated with a frontal wave of low pressure. Mild conditions
with lows in the 20s as a result. The rest of S New England with
lows getting into the teens under clear conditions.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
*/ Highlights ...
- Winter Storm Watch for East Slopes of Berkshires/N Worcester
County Tue afternoon into Wed Morning
*/ Discussion ...
Our winter storm then arrives during the day Tuesday. A deep
mid level shortwave and surface low pressure system will sweep
through the northeast Tuesday-Wednesday.
Models agree that the parent low stays well to our northwest,
while a secondary low forms along the initial cold frontal
boundary as it approaches southern New England. This doesn`t
look to be a hugely impactful storm from the perspective of low
elevation snow, winds, or coastal flooding due to the inland
track and the delay in deepening of the low until it reaches New
England.
The track that has come into focus over the last few model runs
takes this low directly over SNE or even slightly north. As
such it`s quite warm and while most will start as snow, S/SE
winds quickly bring in above freezing air at the surface which
will change snow to rain up to generally a line from Hartford to
Worcester to Lawrence. Further to the northwest where the below
freezing air holds on snow should continue through the event.
Expecting generally 6-8 inches in the Berkshires by the time
precip moves out before 7 am Wednesday; 4-6 inches in the higher
elevations of the Worcester Hills. These locations with the
highest probability of staying purely snow are where Winter
Storm Watches continue. One area of uncertainty remains in just
how quickly and far north the warm air at the surface will make
it late Tuesday. Not a classic CAD setup, given the high north
of us is offset to the east, but hi-res guidance still wants to
signal some of that cold air drainage keeping portions of the
CT river valley and portions of northern MA colder than
currently forecast. Something to watch as we get closer to the
event. As the low picks up steam, downstream colder air wraps
around on the backside and will probably switch everyone back to
a brief period of snow as the system exits early Wednesday
morning.
As mentioned previously, the low really doesn`t begin to deepen
until it is over or north of SNE and as such 925 mb winds don`t
ramp up more than 25-35 kts until it is downstream of us. We
can expect wind gusts of 20-25 kts overnight, mainly along the
coasts.
On Wednesday, the storm moves offshore and ushers in a period
of very efficient CAA as a broad mid-upper level trough moves
overhead. 850 mb temperatures drop from around -3C Tuesday
evening to around -24 C late Wednesday. This will promote good
mixing down of a 35-45 kt LLJ moving overhead during the day.
Model soundings indicate potential for wind gusts of 30-40 kts.
Highs in the upper 20s will feel more like the low teens.
Another thing to monitor Wednesday will be an arctic front that
moves through from west to east during the afternoon and evening
hours. This will bring the potential for some brief but intense
snow squalls that could be hazardous to those on the road. As
the front sweeps through, a band of saturated air in the BL and
lots of low level instability accompanies it...1000-700 mb lapse
rates approach 9 C/KM along and ahead of the front which could
lead to brief but intense heavy snow, low visibilities, and
gusty winds. Behind the front temperatures will plunge as we
head into Wednesday night.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
*/ Highlights ...
- Bone chilling, record-breaking cold late week into weekend
- WIND CHILL headlines likely
- Pattern shift into early February, mild with zipping SW-NE storms
- What side of the envelope, difficult to say on outcomes
*/ Overview ...
Pattern shake-up. W retreat H3 Pacific jet buffered by sub-tropical
Pacific activity echoing poleward. Latent heat release and higher
heights, favorable N Pacific low development shifts over Russia`s
Kamchatka Peninsula. Noting 5-day ensemble means, H5 split flow out
over the NE Pacific / Gulf of Alaska, W CONUS H5 trof promotion with
SW winds across the CONUS. Recent S-carving PV-anomalies across E/NE
N America shunted N, favorable region of storm developments shifts
towards S Greenland. This as the stratospheric polar vortex (10 mb)
tightens up over the N pole.
So how does this play out for New England in the long run? Will be
watching for any surge of anomalously warmer sub-tropical W/SW winds
yielding +H85 temperature anomalies as the ECens suggests into early
February. But challenges into an ongoing phase 5-6 MJO into phase 7,
strength / magnitude of sub-tropical Pacific activity in question,
unclear the impact along with inherent challenges in
forecasting. A nod to NE Pacific split-flow regime, how energy
echoes downstream through a preferred W CONUS trof and, at
times, anticyclonic wave breaks extending from Hawaii into
western N America. The latter, an eye on H85 westerly anomalies
already noted S/E of Hawaii just N of the equator.
Seemingly along the thermal-cusp, will be watching for SW-NE weak
open-wave zipping lows, wobbling, wavering, a challenge to forecast.
New England will be a precip-type playground into the first week of
February. Unclear whether we tap into forecast +H85 temperature
anomalies, or are cut down by undercutting NE-winds with prevailing
preferred high pressure over SE Canada. Break down details, forecast
thinking below. Greater weighting towards EC / ECens as always.
*/ Discussion ...
Wednesday night through Saturday night ...
Cold. Plain and simple. Stout potential vorticity anomaly / trop-
fold contributing to deep surface cyclogenesis across Quebec. The
isallobaric / gradient wind response driving Arctic air across the
NE CONUS into the weekend. Have to watch for WIND CHILL headlines
for late Wednesday through Wednesday night, possibly through as late
as Friday. Cold air advection, steepening lapse rates over time up
to around H7 beneath the trop-fold 0z Thursday, will also have to
watch winds, efficiency for the top of the mixed layer to mix down,
whether we`ll need WIND HEADLINES in addition to some scattered snow
shower activity. H85 temperatures falling down around -25C, can`t
rule out record-breaking H925-7 temperatures within Chatham sounding
profiles per climatology.
A 1030+ high Saturday morn, cold exacerbated by radiational cooling,
especially for areas with deeper snowpack. May come close to record
lows, but a better shot of breaking record lowest high temperatures.
Sunday onward ...
SW-NE weak zipping lows grasping on conduits of sub-tropical air
while training along wavering thermal gradients. Little confidence
on outcomes, will have to wait and see. Numerous variables as to
whether snow pack remains which, if any undercutting cold NE flow
prevails in advance, would aid in maintaining frozen precip-types.
Expecting forward-thump, isentropic-upslope, baroclinic leaf events
with SW-NE lows. Generally weak, fast, with a possible decent sub-
tropical fetch, anywhere from snow to rain, just depends which side
of the envelope S New England will reside upon.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Wednesday/...Moderate confidence.
Overnight...
Mainly VFR, except MVFR CIGS from 2000-2500 ft across E coastal
terminals, which will push westward to the KOWD-KPVD corridor.
Can`t rule out flurry activity with minor VSBY impacts along the
immediate coast from about KBVY-KGHG from around 08Z-12Z. MVFR
CIGS push further W across the interior towards Tuesday
morning.
Tuesday into Tuesday night...
MVFR becoming widespread, lowering to IFR-LIFR with onset SN.
Impacts spreading W to E roughly 16-21z. S-coastal locations
remaining as RA, the transition RA / SN line progressing as far
N as BDL-ORH-BVY roughly 4z before changing back to SN. Lower
VSBYs with SN. Blustery E/SE flow, however may see some N
drainage winds within interior valleys throughout before winds
shift W by Wednesday morning.
Wednesday...
Blustery W winds, gusts of around 25 to 35 kts, possibly as high
as 40 kts. SCT-BKN low-end VFR CIGs around 040, the threat of
SN/+SN showers with briefing IFR-LIFR impacts and quick snow
accumulations on any and all surfaces.
KBOS Terminal...
MVFR CIGs developing this evening, could be some attendant snow
flurry activity, however thinking little to no impact to VSBYs.
Will see bigger SN impacts towards the afternoon into evening
push Tuesday.
KBDL Terminal...
Quiet night, but expect lower conditions to work in closer to
noon Tuesday with onset SN. IFR-LIFR prevailing through the
Tuesday PM push.
Outlook /Wednesday Night through Saturday/...Moderate Confidence
Wednesday Night: VFR. Strong winds with local gusts up to
40 kt.
Thursday through Saturday: VFR. Breezy.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Wednesday/...High confidence.
Tonight ...
High pressure builds over waters tonight with N/NE winds.
Tuesday into Tuesday night ...
Increasing SE flow Tue as high pressure heads to Maritimes and
low pressure tracks through eastern Great Lakes. Expect a weaker
low to develop Tue night and track through southern New England.
Winds should reach SCA on most of waters with gusts of 25-30kt
possible.
Wednesday...
Strong west winds increasing to 35-45 kts. Seas building to
9-11 ft on the southern waters, 6-8 ft on the eastern waters.
Arctic air sweeping in, the threat for moderate freezing spray
by late Wednesday.
Outlook /Wednesday Night through Saturday/...Moderate Confidence
Wednesday Night: Low risk for gale force winds with local gusts
up to 45 kt. Rough seas up to 12 ft. Freezing spray likely,
slight chance of snow showers.
Thursday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Freezing spray likely,
slight chance of snow showers.
Thursday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Areas of rough seas. Freezing spray
likely.
Friday: Low risk for Small Craft Advisory winds with gusts up
to 30 kt. Local rough seas. Freezing spray likely.
Friday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Freezing spray likely.
Saturday: Winds less than 25 kt. Seas locally approaching 5 ft.
&&
.CLIMATE...
Record LOWEST High Temperatures for Thursday, January 31st...
Boston ....... 12 (1920, 1935)
Hartford ..... 15 (1951)
Providence ... 15 (1935)
Worcester .... 11 (1951)
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Winter Storm Watch from Tuesday afternoon through Wednesday
morning for MAZ002>004-008-009.
RI...None.
MARINE...Gale Watch from Wednesday afternoon through late Wednesday
night for ANZ231>235-237-250-251-254>256.
&&
$$
SYNOPSIS...Sipprell/BW
NEAR TERM...Sipprell/EVT
SHORT TERM...BW
LONG TERM...Sipprell
AVIATION...Sipprell/EVT/BW
MARINE...Sipprell/EVT/BW
CLIMATE...Staff
Area Forecast Discussion
National Weather Service Louisville KY
945 PM EST Mon Jan 28 2019
.Forecast Update...
Issued at 945 PM EST Mon Jan 28 2019
Surface cold front continues to push eastward through the US 27/127
corridor and will push through Frankfort shortly and then through
Lexington in the next couple of hours. Precipitation has been
showing a diminishing trend on radar as upper support pulls off to
the northeast. Back edge of precipitation is just ahead of the
freezing line which is approaching the I-65 corridor. We`ve seen a
mix of sleet and snow with this precipitation, though as the colder
air has grown deeper, the mix was very short lived and went over to
snow rather quickly. The snow is rather light and really has not
accumulated at all.
Overall forecast remains on track. We`ll see precipitation shield
head on off to the east over the next few hours with colder air
pushing from western KY through the remainder of the state
overnight. Probably will see a batch of flurries pass through
southern IN and parts of N/C KY this evening and into the early
overnight, but again, no real accumulations are expected.
Did a quick refresh of the Special Weather Statement that was issued
earlier. We`ll have some wet roadways across the region this
evening and with temps dropping into the teens overnight, some icy
spots will be possible. Road temps are running above freezing and
there will be a lag before they drop down below freezing.
Combination of much drier air, gusty northwest winds, and some
traffic on the main road will likely allow them to dry out a bit
this evening and into the overnight. However, secondary roads that
are protected from the wind and less traveled could see some black
ice overnight.
Issued at 841 PM EST Mon Jan 28 2019
Surface cold front has pushed just east of the I-65 corridor this
evening. Band of light rain showers continues in advance of the
front and will produce about 0.02 to 0.04 inches of rainfall as it
sweeps eastward across central KY this evening. Temperatures have
fallen into the lower 40s in areas east of I-65. Just west of I-65,
temps have fallen into the lower 30s with the freezing line along a
line near Owensboro south westward to near Paducah.
Just behind the front, we do have about a 20 mile wide band of light
precipitation. This is likely a mix of sleet and some light snow
flurries. With temps still above freezing, we`re not expecting much
of any accumulation, sans a quick deck duster or rooftop dusting.
Colder air will continue to work into the region this evening, with
the freezing line likely reaching the I-65 corridor in the next hour
or so and then quickly racing eastward toward the I-75 corridor by
midnight.
Issued at 631 PM EST Mon Jan 28 2019
Surface cold front has just pushed through southwestern IN and is
entering far northwestern KY. Out ahead of this front, widespread
light rain showers are occurring and will likely drop between 0.01
and 0.04 inches of rainfall as they move through. Based on radar
observations, not much rainfall is occurring behind the front, so a
brief change over to snow still looks possible in the I-65 corridor
this evening, but that window looks to be closing fairly rapidly.
Actual freezing line is trailing back behind the front by 50-60
miles or so.
That freezing line will reach in the IN/IL border shortly and then
push into KY this evening. Latest HRRR runs seems to have captured
this feature well and push the freezing line toward the I-65
corridor by 10 PM or so and then into the I-75 corridor by midnight.
&&
.Short Term...(This evening through Tuesday)
Issued at 315 PM EST Mon Jan 28 2019
A narrow rain band along a cold front curved from IND to EVV to PAH
this afternoon, with hints of sprinkles/virga on radar out ahead of
the primary band. Upstream, cold air has been lagging the precip all
day. And GOES-16 low level water vapor imagery shows the dry slot
that will shut off precip fairly quickly tonight. Overall, it looks
like a brief period of light to moderate rain at any one spot. Some
areas could see precip end as a very brief period of light snow, but
this shouldn`t amount to much. In addition, temperatures have surged
into the mid 40s to mid 50s this afternoon. At least some of any
brief snow will likely be lost to melting.
However, strong CAA will be underway during the 00-06z time frame.
Mid-level PVA could help enhance the post-frontal precip slightly.
If a band of snow could develop on the western edge of the deeper
moisture plume, some spots could pick up a dusting. However, most
locations will see little to no accumulation. So have cancelled the
Winter Weather Advisory.
Temperatures dropping into the mid teens to lower 20s Tuesday
morning could also create some slick spots with any lingering
moisture/dusting of snow. Otherwise, Tuesday will be chilly and
breezy. Temperatures won`t make it out of the 20s. A deep, highly
anomalous upper low will continue to rotate southeast over the Great
Lakes on Tuesday. Arctic high begins to build SE, sending even
colder air our way Tuesday evening.
.Long Term...(Tuesday night through Monday)
Issued at 415 PM EST Mon Jan 28 2019
...ARCTIC AIR FOR MIDWEEK...
The big story during the extended is the intrusion of arctic air
into the Ohio Valley for Wednesday and Thursday. Temperatures will
plummet to the single digits - above and below zero - for all but
the far southern Kentucky counties by sunrise Wednesday, and again
on Thursday morning. For southern Indiana, daytime highs on
Wednesday will remain in single digits.
The extreme temperatures, along with northwest winds 10-15 mph
through midday Wednesday, will result in wind chill indices of -10
to -20 Fahrenheit into the early afternoon. While there will be
some sunshine to go along with the frigid air, make no mistake -
this will be COLD! For that reason, we`ve gone with a Wind Chill
Advisory from 07Z to 19Z Wednesday. While some VERY light snow of
flurries could fall overnight as the cold air arrives, this dry snow
will be more flurries than anything else, with only trace amounts
expected.
Almost as quickly as it arrives, the cold air will move out during
the latter half of the week. WHile Thursday morning temperatures
will be as cold as - or colder than - Wednesday morning lows, the
winds will be lighter as the ridge of high pressure associated with
the cold drifts over the area. By Thursday afternoon, the surface
high and thermal trof will have passed to the east, and return flow
from the south will start to moderate temperatures.
As the warm air moves in to replace the cold air, there is another
chance of snowfall Thursday night into Friday morning. While it is
possible some locations could pick up an inch of accumulation, it
will be short lived, as temperatures push above freezing by late
morning, topping out in the upper 30s to lower 40s by afternoon.
Saturday will be dry, but another chance for rain comes in with the
warmer air on Sunday.
Temperatures continue to rise through the weekend with highs in the
upper 40s and 50s Saturday, and in the 50s to around 60 Sunday and
Monday.
&&
.Aviation...(00Z TAF Issuance)
Updated at 625 PM EST Mon Jan 28 2019
Early evening surface analysis reveals surface cold front just
entering the WFO LMK forecast area. The front just pushed through
KHNB and is heading eastward. Out ahead of of it light rain is
being reported and will continue for a time this evening. Winds out
ahead of the front have been from the southwest and will continue to
be gusty this evening. Sustained winds of 15-20kts and gusts to
30kts will be possible at times. Ceilings will start off VFR, but
will likely drop into the MVFR range this evening. Visibilities
look to remain generally VFR.
Cold front looks to push through KSDF/KBWG between 29/00-01Z and
then over at KLEX around 29/03-04Z. Precipitation is likely to end
just after frontal passage and we could see a very brief period of
snow at KSDF/KBWG, but it is not expected to amount to much. Some
light snow would be possible over at KLEX toward midnight if
precipitation lingers long enough to get caught up with the
approaching cold air.
Behind the front, look for winds to shift around to the west/west-
northwest and they will remain gusty. Current thinking is that
winds will remain around 280/290 degrees with sustained speeds of 12-
15kt with gusts to 25 kts at times. Ceilings look to remain around
2200-2300ft AGL in the post frontal flow. Winds should slacken off
late tonight with ceilings improving to VFR after 29/12Z.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Wind Chill Advisory from 2 AM EST /1 AM CST/ to 2 PM EST /1 PM
CST/ Wednesday for INZ076>079-083-084-089>092.
KY...Wind Chill Advisory from 6 AM EST /5 AM CST/ to 1 PM EST /noon
CST/ Wednesday for KYZ023>043-045>049-053.
&&
$$
Update.......MJ
Short Term...EBW
Long Term....JBS
Aviation.....MJ
Area Forecast Discussion
National Weather Service Nashville TN
815 PM CST Mon Jan 28 2019
.UPDATE...
FOR EVENING DISCUSSION.
&&
.DISCUSSION...
Well, we`re creeping up on game time here and it`s not looking
good. With the progression of the current precipitation on radar,
along with temperatures still in the 40s and low 50s across all of
Middle TN, combined with the latest HRRR guidance, we`re going to
back of considerably on the snowfall totals and trim a couple more
counties off the back side of the Winter Weather Advisory. I will,
however, maintain the Cumberland Plateau in the Advisory from
midnight until 6 am. This means we`ll also be reducing the total number
of hours of the advisory (removing 6 am - noon), as latest
guidance also has all of the precipitation east of Middle TN by 6
am.
This doesn`t negate the eventual arrive of pretty cold air into
Middle TN tonight. It`ll just be later than guidance had us
believing. Single digit wind chills north of I-40 and teens
elsewhere will be here in the morning.
Updates will be out shortly.
&&
.AVIATION...
00Z TAF DISCUSSION.
BNA/MQY/CKV/CSV...A strong cold front is making its way across
Middle Tennessee this evening, but it`s coming through a lot drier
than previously forecast. Look for light precipitation this
evening, mainly behind the surface front, mixing with and then
changing to snow before ending. Ceilings will drop to MVFR for a
few hours before improving later tonight or early Tuesday morning.
Precipitation will be a little heavier and ceilings a little worse
farther east, so CSV will experience lower visibilities and
ceilings than the rest of our terminals.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from midnight tonight to 6 AM CST
Tuesday for Cannon-Coffee-Cumberland-De Kalb-Fentress-Grundy-
Overton-Pickett-Putnam-Van Buren-Warren-White.
&&
$$
DISCUSSION......Unger
AVIATION........08