Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/02/21
Area Forecast Discussion
National Weather Service Binghamton NY
918 PM EST Fri Jan 1 2021
A wintry mix of freezing rain, sleet, and some snow will change
over to rain late tonight and early Saturday morning as warmer
air works in. A few rain and snow showers will linger into
Saturday. Dry weather briefly returns Saturday night, then
another storm will bring more snow Sunday and Sunday night.
.NEAR TERM /THROUGH SATURDAY/...
900 PM Update...
Used HRRR 2m temperatures for surface temperatures in grids
which fit the observations better than NBM. Then used RAP13
with the top down tool from BTV for the precipitation type. We
will see a warm wedge aloft at 850 mb come through between 06z
and 09z and this should lead to warming in the surface layer
above freezing most places. In the meantime, there will be a dry
slot coming thru between 9 and 11 pm but the HRRR does have
another batch of precipitation coming through 06z-09z. Many
areas especially Finger lakes and a lot of valley locations
west of I-81 will see mostly rain. East of I-81 and especially
Poconos/Catskills to Upper Mohawk likely will see a round of
freezing rain. This could bring planar or flat ice totals to .5"
in a few higher terrain sites in the Poconos/Catskills. Farther
north toward the Mohawk Valley, these areas should see a period
of freezing rain overnight. Since these areas have had more snow
and sleet at this time, total ice accumulations will be lower
up there than in our northeast PA/Catskills higher terrain areas.
We have received several reports of close to .2" of flat ice in
northeast PA and the southern tier. So the additional ice puts
many areas around .3" or so. Of course the valleys have less for
the most part. A quick look at the power outage maps shows very
little so this event looks to have mainly a travel impacts so
far and we don`t expect enough additional radial ice to
significantly impact power.
Expanded the winter weather advisory for areas west of I-81
where we feel many higher terrain areas will still be close to
freezing as next batch of light precipitation arrives.
600 PM Update...
Looking at surface observations and radar mosaic imagery there
was a large area of temperatures from the upper 20s to lower
30s from central NY/northeast PA south into the PA mountains
and just east to northern VA and western MD. Widespread freezing
rain was reported in much of northern and central PA into south
central PA and down into the central Appalachians and points
just to the east. Also there was widespread freezing rain in
south central NY and the Finger Lakes. Some sleet and snow was
developing in north central NY to Catskills initially, as
expected with colder air aloft in place at the onset. The
surface flow was easterly with dewpoints from the low to mid 20s
in eastern NY to upper 20s to near 30 down into central and
south central PA. RAP analysis data initialized at 23z shows a
wedge of colder air down the Appalachian mountains in the
typical cold air damming fashion. 850 mb temperatures range from
4-5C in northern WV to 1-3C farther north into south
central/northeast PA. Temperatures at 850 mb drop below freezing
across much of eastern and north central NY where we expect
more snow initially. Based on the temperatures and still some
drier air advecting into northeast PA and central NY at the
surface we have increased ice accumulation (planar) a tad.
Basically we have much of our forecast area between .1 and .25"
with locally above .25" in our higher terrain of Catskills and
Poconos. Our deeper valleys and along the Finger Lakes we have
less than .1". As for impacts, we don`t expect any widespread
power outages, especially since we are forecasting planar ice.
Warmer air eventually will advect in aloft and mix down to the
surface with the precipitation later this evening changing
freezing rain to all rain. The hold outs will be from the upper
Mohawk Valley to Catskills/Poconos where the cold air loves to
hang tough. These areas will see more freezing rain.
330 PM Update...
An upper level low is currently rotating over Missouri and southern
IL, with strong southerly flow out ahead of it is advecting
increasingly warm and moist air into the region. Precipitation
associated with the warm front is already moving into our northeast
PA zones at this time, but nailing down the precipitation type is
proving difficult with very nearly everything being reported across
northern PA so far. Surface temperatures hover in the lower to mid
30s with dewpoints in the 20s. With the onset of precipitation, sites
more to our southwest have been able to wet bulb down below
freezing. Given a fairly warm airmass aloft, the primary concern is
for sleet and freezing rain. Indeed, many locations are already
reporting freezing rain. However, even aloft, temperatures have
been able to cool sufficiently in some spots to allow for more of a
snow profile. A nearby NUCAPS sounding from earlier this afternoon
showed a fairly cool, moist sounding that would indicate mainly snow
or a rain/snow mix. So, with the onset, will keep in a chance for
some flakes, but then a rapid change over to sleet and finally
freezing rain is expected pretty much within an hour of the onset
for most locations as precipitation continues to spread northward.
This may result in some light snow/sleet totals below an inch over
Into the night, most of the area should see a change over to rain as
surface temperatures slowly warm through the 30s. However, the
higher elevations of the Catskills and Poconos, as well as portions
of Steuben county, may be able to hang on to freezing rain a bit
longer. Additionally, northern Oneida county may be able to see snow
and sleet well into the night before a change mainly over to
freezing rain after midnight. This could yield higher snow totals
there up to 2 to 3 inches overnight.
Precipitation lifts northeast out of the area into Saturday as the
low moves moves northeast towards southern Ontario/Quebec. Cooling
temperatures aloft will allow for a change back over to rain or a
rain/snow mix where precipitation can linger into Saturday morning.
This would be mainly over northern Oneida county.
Storm total QPF generally around a half to three quarters of an inch
is expected. With much of the area turning over to freezing rain
overnight, at least a light glaze of ice is expected area-wide, but
heavier totals up to a quarter inch are not out of the question
especially across the Catskills and Poconos.
Temperatures rise up into the mid and upper 30s across central NY
Saturday, and into the upper 30s and lower 40s in northeast PA.
Winds shifting to the northwest will increase to around 10 to 15
mph, and gust as high as 20 mph particularly over the higher
elevations. This may be something to keep an eye on, considering any
lingering ice accumulations.
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
220 PM Update...
High pressure filtering across the region from the Great Lakes will
partially clear skies and allow for a cold overnight period with
lows dipping well into the 20s on Saturday night.
On Sunday, a moderately strong upper level low will transition
from the Ohio Valley into Western New York by evening. This
feature will transfer energy to a newly developing surface low
off the Virgina capes. This system will track northeastward
spreading snow into NY and PA from late morning through Sunday
evening. The best forcing looks to be over NEPA closest to the
track of the new low and along the base of the upper trof where
accumulations should be highest. A marginal, near isothermal
profile at times indicates a chance for some mixed precipitation
for NEPA. Can`t totally rule out portions of the Southern Tier
and Catskills for a little sleet, but overall, model soundings
suggest this as a snow event along with some possible rain in
the valleys as temperatures breech the mid 30s during the
Snow accumulations of two to four inches are expected over the
higher terrain of NE Pennsylvania and the Catskills of NY. Expect
one to three inches along the Southern Tier and lesser amounts to
Steady snow will pull out on Sunday evening and diminish to
scattered snow showers through the night. Quieter weather expected
by Monday morning.
.LONG TERM /MONDAY THROUGH FRIDAY/...
Quiet weather will prevail between Monday and Wednesday as weak high
pressure moves through the region. A few flurries or light snow
showers are possible Monday near the lakes.
Light rain or snow showers are possible Thursday as milder air
streams into NY and PA.
Afternoon temperatures will be mainly in the middle 30s through the
middle of the week.
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
700 pm update...
Precipitation has moved in and has largely started as FZRA and
PL for all terminals but RME where enough cold air is in place
for snow. As the LLJ increases aloft, warm air moves in and will
transition all Ptypes to FZRA and eventually RA as the surface
temperatures warm above freezing from S to N. LLWS has been put
in at all terminals to account for the LLJ. Ceilings are
expected to fall to IFR conditions for most of the night. As the
low moves off to the NE, moist NW flow keeps low clouds around
tomorrow but ceilings look to rise to MVFR and Fuel Alternate
conditions. There is a chance that AVP will be able to get to
VFR conditions late tomorrow as downsloping into the Wyoming
Valley helps to dry out the airmass.
Saturday night..High pressure with some .
Sunday...Occasional restrictions possible in rain and snow
Monday through Wednesday...Mainly VFR.
PA...Winter Weather Advisory until 7 AM EST Saturday for PAZ040-048-
Winter Weather Advisory until 5 AM EST Saturday for PAZ038-039-
NY...Winter Weather Advisory until 7 AM EST Saturday for NYZ018-036-
Winter Weather Advisory until 5 AM EST Saturday for NYZ015>017-
Winter Weather Advisory until 10 AM EST Saturday for NYZ009-
Area Forecast Discussion...Updated
National Weather Service Peachtree City GA
950 PM EST Fri Jan 1 2021
No big changes. Rain continues to move into east central GA. Rain has
ended for the night over northwest and the north half of the area
should be dry until rain moves back Saturday afternoon.
.SHORT TERM /Tonight through Saturday Night/...
A prefrontal line of showers and a few embedded isolated
thunderstorms continues to push eastward across the forecast area
this afternoon. The approaching cold front extends southward across
central Alabama from a surface low currently over the mid-
Mississippi Valley. Meanwhile, the last vestiges of a surface wedge
are slowly being scoured out of far northeast Georgia as the surface
front lifts northward. As far as the severe threat is concerned, the
limiting factor continues to be low surface instability despite
plentiful shear. With that said, through the reminder of the
afternoon, a marginal severe risk will remain given a strong low-
level jet and increasing low-level warm advection along the warm
front. Any thunderstorms that continue to be able to strengthen in
this zone would bring an isolated damaging wind gust or brief spin-
up tornado threat.
Otherwise, while PWs are elevated, quick storm motion has served to
limit overall precipitation accumulations. However, areas where
precipitation has had more of an opportunity to train from this
morning through this afternoon have received higher totals,
particularly across northeast Georgia. Localized minor hydrological
issues remain possible in these locations through this evening
by which time the rain tapers off.
By Saturday morning, the cold front will have made progress into
eastern/central portions of the CWA where it will stall. The morning
will bring a brief respite of drier conditions across much of the
area, with the exception of perhaps the far southeastern CWA. Dry
weather will be short-lived, though, as a shortwave lifts northeast
out of Texas into the ArkLaTex. This will induce the development of
a low along the front, and moisture will quickly surge back
northward into the area. Thus, PoPs will be on a quick increase from
tomorrow afternoon into tomorrow night, particularly across the
southeastern half of the area. No strong or severe thunderstorms are
expected given very weak instability. However, heavy rainfall totals
are possible in southeastern portions of the CWA, particularly
overnight tomorrow night where totals could approach 2". These
totals could be sufficient for localized minor hydro concerns,
though significant flooding issues are not expected.
.LONG TERM /Sunday through Friday/...
The long term period will be much quieter than the short term as
the forecast area returns to mostly clear and dry, diurnal
conditions following a cold front that will drop PWATS below 0.5
inches through at least Wednesday night. In the meantime, surface
high pressure will take hold with upper-level ridging aloft
allowing afternoon high temps to climb into the 50s and low 60s
each day for the first half of the week.
Afterwards, another synoptic trough will once again set up over
the eastern CONUS with a storm system expected sometime between
Thursday and Friday night. Models are beginning to come into
alignment but there are still major discrepancies as to the
timing of this frontal system, up to 18 hours in some cases, but
improving from timing differences during the previous shift. There
will also be an chance for some light snow showers for North
Georgia with some rap around moisture Thursday night into Friday
morning, but we`ll have to see if colder temperatures continue to
hang around with the precip as the week progresses.
.AVIATION... 00Z Update...
Showers have moved east of the taf sites...except KMCN will have
showers until around 02z. IFR ceilings should remain largely the
rule overnight...though some brief...patchy improvement to MVFR
or even VFR remain possible at times. More persistent improvement
to VFR is more likely by 10-12z Saturday. Winds will remain SSW
4 to 7 kts overnight...becoming west by 10z 8 to 10kts.
//ATL Confidence...00Z Update...
Low to medium confidence on cigs through tonight.
Medium to High confidence on winds and precip timing.
.PRELIMINARY POINT TEMPS/POPS...
Athens 52 66 45 55 / 60 50 90 5
Atlanta 50 63 42 51 / 30 40 70 5
Blairsville 45 62 39 46 / 50 10 60 10
Cartersville 46 62 40 51 / 30 20 50 5
Columbus 53 66 43 55 / 30 70 70 5
Gainesville 49 63 44 51 / 50 30 80 5
Macon 58 67 46 59 / 60 80 90 5
Rome 46 62 40 51 / 20 10 40 5
Peachtree City 49 66 41 54 / 30 50 60 5
Vidalia 65 70 54 62 / 70 90 90 5
Area Forecast Discussion
National Weather Service Jacksonville FL
936 PM EST Fri Jan 1 2021
...WAVES OF HEAVY DOWNPOURS TO IMPACT PORTIONS OF INLAND SOUTHEAST
GA THROUGH SATURDAY NIGHT...
Late evening surface analysis depicts complex low pressure (1007
millibars) over the Ohio and Tennessee Valleys, with a
decelerating cold front stretching southward from this storm
system to the FL panhandle and extending into the central Gulf of
Mexico. Strong high pressure (1031 millibars) over New England was
keeping a wedge of cool air over the Carolinas and the southern
Appalachians, with southerly low level flow to the south of this
wedge over our area. Aloft...deep-layered ridging was centered
over the Bahamas, while a potent shortwave trough was accelerating
east-northeastward across the lower Great Lakes region, with
another potent shortwave trough emerging from the Desert Southwest
into west Texas. A ribbon of deep moisture remains in place ahead
of the upstream cold front over inland southeast GA, with latest
RAP analysis indicating PWAT values of 1.7-1.9 inches for
locations west and northwest of Waycross. Within this corridor of
deep moisture, heavy downpours streamed over the Ocmulgee and
western Altamaha Rivers earlier this evening, and another wave of
downpours currently moving onshore along the FL Big Bend coast was
poised to race northeastward towards these areas after midnight.
Mid and high altitude cloud cover otherwise blankets our region,
with some low stratus hugging the coast from Amelia Island /
Fernandina Beach northward. Temperatures at 02Z were generally in
the 65-70 degree range, with unseasonably high dewpoints in the
mid to upper 60s prevailing area-wide.
Potent shortwave troughing accelerating northeastward through the
lower Great Lakes states will continue to move away from our
region overnight, resulting in the frontal boundary to the west of
our region stalling overnight. Another wave of heavy downpours
will quickly move northeastward across inland southeast GA after
midnight, providing another 0.25 to 0.5 inches of rainfall for
areas west and northwest of Waycross that received up to an inch
of rain this evening. Meanwhile, the large trough aloft entering
west Texas this evening will pivot northeastward across the Ozarks
by Saturday afternoon and will then accelerate across the
Tennessee Valley on Saturday night. This feature will create a
highly diffluent flow pattern aloft over the Gulf of Mexico,
resulting in a wave of low pressure developing along the stalled
frontal boundary towards noon on Saturday. The increasingly
diffluent flow aloft will continue to send waves of convection and
downpours from the Gulf of Mexico northeastward across the FL Big
Bend region and into inland portions of southeast GA through
Saturday night, with only a few showers possible elsewhere as
ridging aloft only slowly slides eastward by late Saturday. Lows
tonight will only fall to the low and mid 60s area-wide, with
highs on Saturday remaining in the low to mid 70s for inland
southeast GA and the upper 70s to lower 80s elsewhere.
Areas of dense sea fog will remain possible tonight through early
Sunday afternoon over the near shore waters adjacent to southeast
GA and possibly the waters surrounding Amelia Island. Small Craft
should continue to Exercise Caution if venturing to the offshore
waters, where southerly winds will be sustained at 15-20 knots
through at least midnight and 4-6 foot seas will prevail through
Sunday. Otherwise, a cold front stretching from the Tennessee
Valley southward to the central Gulf of Mexico will stall to the
west of the Georgia waters on Saturday as low pressure develops
along the front over the Gulf of Mexico and lifts northward. This
low pressure center will then accelerate northeastward while
slowly strengthening on Saturday night, propelling the frontal
boundary eastward across our local waters during the predawn and
early morning hours on Sunday, accompanied by showers. High
pressure will then build along the northern Gulf coast region
early next week, with prevailing offshore and gradually
diminishing seas expected through Tuesday.
Rip Currents: A moderate risk of rip currents will continue at
area beaches on Saturday, with low risks expected Sunday and early
Some of the 00Z Sat guidance is indicating the potential for 2-4
inches of additional rainfall for locations west and northwest of
Waycross, where a Flood Watch or even a Flash Flood Watch may be
considered for Saturday and Saturday night as downpours continue
to train over increasingly saturated soils, particularly for
locations along the Ocmulgee and Altamaha Rivers. Rises along
these rivers are likely later this weekend and into next week.
.PREV DISCUSSION [704 PM EST]...
.NEAR TERM [Through Tonight]...
Flow aloft will continue to veer as shortwave energy shoves the
front and associated moisture into the region late today and
tonight. Current POPs look good with minor adjustments, with
scattered showers moving into southeast GA this afternoon and
better rain chances into the evening and overnight hours. A few
pop-up showers possible this aftn over northeast FL near
convergent lines. Enough instability with MUCAPEs near 300-700
will support a slight chance of thunderstorms late today and
tonight over inland southeast GA. A risk of an isolated strong to
severe storm remains possible this evening and overnight over
inland southeast GA northwest of a line from Baxley to Pearson
where bulk shear values of 40 kt are noted.
Highs today well above normal in the upper 70s to lower 80s, with
near record highs over northeast FL and probably only 2-3 deg shy.
Sfc winds breezy at times from the south near 15 mph and gusty.
.SHORT TERM [Saturday Through Sunday Night]...
The slow moving cold front to our west is expected to become
reinvigorated Saturday afternoon as an upper level +PV anomaly
digs into the Southern Plains and develops a surface low along the
front in the north-central Gulf waters. The upper level low will
then lift into the OH Valley Saturday night, dragging the front
eastward across the southeastern US. Scattered showers and
isolated thunderstorms will continue Saturday with the highest
chances/coverage over inland SE GA, but the majority of the
precipitation is expected to fall Saturday night. Heavy rain is
possible Saturday and Saturday night, mostly across southeast
Georgia. Rainfall amounts of 1-2.5 inches are forecast, and
locally higher amounts of 3-4 inches are possible which could lead
to localized ponding and street flooding. WPC has a slight risk of
excessive rainfall for tomorrow over a portion of Jeff Davis,
Coffee, and Atkinson counties in SE GA. In addition to the heavy
rainfall threat, a portion of the low level jet may still line up
over our inland GA counties and deep layer shear of around 50
knots suggests some of the storms that develop Sat/Sat night could
produce some strong to severe wind gusts (40-60 mph). Even outside
of storms, breezy winds occasionally gusting to around 20-30 mph
will be possible as we`ve seen today.
The upper low driving this system will continue to lift
northeastward into the Great Lakes Sunday and with the main energy
driving the system lifting so far away, the front will lose much
of its steam as it continues to exit our area of responsibility
Sunday morning. Behind the front, cooler, drier air will begin to
filter into the region. After several days with highs in the upper
70s-low 80s, Sunday will see highs struggling to reach 60 over
inland SE GA and 70 in NE FL. Lows Sunday night will dip into the
mid-upper 30s in the Suwannee Valley and frost is possible early
.LONG TERM [Monday Through Friday]...
Low level ridging will build in over the southeast early next week
in the wake of the cold front. Around mid-week another upper low
will move into the Plains and develop the next cold front to
approach the region. As this developing system pushes the low
level ridge offshore around Wed/Thu, onshore flow will begin to
return some moisture and low end rain chances ahead of the next
front could return Thursday, with the front crossing through the
area around Friday. Temperatures next week should be near normal
for this time of year- peaking in the 60s in the afternoons and
dipping to the upper 30s/low 40s in the mornings.
[Through 00Z Sunday]
VFR conditions will prevail through at least 06Z at the regional
terminals. Brief light showers will be possible at SSI and JAX
through around 04Z, potentially producing ceilings around 4,000
feet. Otherwise, sea fog will possibly set in at SSI after 06Z,
with higher probabilities for IFR conditions occurring after 09Z,
followed by the potential for a brief period of LIFR ceilings
around 300-400 feet towards 12Z. IFR ceilings will likely prevail
at SSI through around 18Z, with ceilings then lifting to MVFR
around 1,500 feet. Elsewhere, MVFR ceilings of 1,200-2,500 feet
will likely develop shortly after 12Z, with brief periods of IFR
to MVFR ceilings at GNV after 09Z. Confidence was too low to
include IFR conditions at GNV at this time. Showers may begin to
impact SSI after 16Z. Southerly low level winds will increase
overnight, with speeds around 30-35 knots expected at the regional
terminals towards 09Z, possibly reaching marginal low level wind
shear criteria at the regional terminals during the predawn and
early morning hours on Saturday as surface winds remain sustained
at or below 5 knots. Sustained southerly surface winds will then
increase to near 10 knots after 15Z.
.PRELIMINARY POINT TEMPS/POPS...
AMG 66 72 54 62 38 / 80 90 80 0 0
SSI 61 71 59 67 42 / 20 30 60 20 0
JAX 64 80 61 70 41 / 20 20 50 20 0
SGJ 65 79 63 71 44 / 10 20 30 30 0
GNV 63 80 62 69 39 / 10 20 60 20 0
OCF 63 81 62 72 41 / 10 10 50 20 0
Area Forecast Discussion
National Weather Service North Platte NE
525 PM CST Fri Jan 1 2021
.SHORT TERM...(This evening through Saturday night)
Issued at 331 PM CST Fri Jan 1 2021
The RAP model shows dry air moving in tonight and precipitable water
will fall to around 0.20 inches across western Nebraska by morning.
This should set the stage for fairly strong radiational cooling.
Winds aloft at h850mb are 15kts supporting light sfc winds. The
cooler NAM and ECM guidance is in place for lows in the teens and
single digits. The SREF suggests the potential for valley fog
tonight and patchy fog is in place across parts of ncntl and swrn
Temperatures aloft warm a few degrees Saturday. The bias corrected
guidance blend suggested highs in the mid and upper 40s. The
temperature forecast uses this blend but marks down temperatures a
couple of degrees for existing snow cover. The models suggest full
A weak cold front will work through western and north central
Nebraska Saturday night. This should produce a period of cloudiness
according to the model consensus but still potentially mostly clear
throughout the night. The frontal boundary should disrupt the
nighttime cooling cycle and the bias corrected guidance blend
suggested lows in the upper teens to lower 20s.
.LONG TERM...(Sunday through Friday)
Issued at 331 PM CST Fri Jan 1 2021
The models are in good agreement projecting a warming trend Sunday
through Tuesday followed by a strong cold front Wednesday with
cold weather continuing Thursday. The ECM is the strongest and
produces about a 1/4 inches of liquid which would be rain changing
to snow. The ECM ensemble is more relaxed with around 1/10 of an
inch or less liquid which is similar to the GFS and it`s ensemble.
The origin of the disturbance is currently across the Aleutians
so there are many days and miles before this system will affect
Nebraska. For this forecast, just slight chance POPs are in place.
Otherwise, temperatures around 5C at h850mb until Wednesday should
easily support highs in the 40s to around 50. The cold front will
send the h850mb temperatures to around -5C which would support highs
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 519 PM CST Fri Jan 1 2021
VFR conditions expected to prevail for the next 24 hours. Clear
skies and light west/southwest winds are expected, with no
impacts to aviation anticipated.
Issued at 331 PM CST Fri Jan 1 2021
Time-lapse camera shots from the NDOR clearly show floodwater
deepening on accretion ground in the primary flood plain of the
North Platte river near Lewellen. A flood advisory continues in
place for the foreseeable future. Overnight lows in the single
digits appear to have been sufficient to create the necessary ice
Area Forecast Discussion
National Weather Service Louisville KY
836 PM EST Fri Jan 1 2021
Issued at 835 PM EST Fri Jan 1 2021
Winds still are gusting in the 25-35 mph range now, below threshold
for a wind advisory...so allowed that product to expire earlier this
hour. Surface low pressure now is analyzed to our north and east,
and measurable precip has shifted into eastern KY. It still looks
like we`ll get some patches of drizzle overnight and into Saturday
morning. Have updated the forecast to remove the headline and trend
toward latest temperature/wind guidance.
.Short Term...(This evening through Saturday)
Issued at 311 PM EST Fri Jan 1 2021
...Gusty Winds & A Few Strong Showers or Storms Possible...
The warm sector has quickly become established over most of our
region at this hour as KY Mesonet obs show low 70s readings across
the southern half of central KY at this hour. The 60 degree line has
almost made it to the Ohio River, and will continue advecting
northward on the aid of good heating, and with some advection ahead
of a surface low currently over west central KY.
We`ve seen some deeper mixing where clouds have cleared out in the
this dry slot, and even a couple of gusts just over 40 mph. Will go
ahead with a short Wind Advisory in anticipation of a few more 40+
gusts popping up. We do have another couple/few hours of the 40-50
knot low level jet core over our warm sector, and sounding show low
level thermal profiles capable of tapping into that higher momentum
air aloft, so can`t rule out the stronger gusts developing.
Speaking of stronger gusts, we also have the threat of some low
topped convection for the afternoon and early evening. Have started
to see a broken line of showers develop across our NW CWA, just
ahead of a convergent surface feature that will push into our north
central CWA over the next 1 to 2 hours. As this occurs, there should
be better alignment of enough low level convergence and the
instability axis that is now ranging around 500-750 J/KG of near
surface based CAPE across south central KY. The HRRR has suggested
now for a couple of consistent runs (along with the 12z NAM 12
solution) that scattered to numerous low topped showers or storms
will develop across north central KY and then move toward the
Bluegrass region into the early evening hours. If these storms do
get a bit better organized, then isolated instances of stronger
gusty winds will be on the table. At this point, think the threat
for any tornadic activity would be a bit lower right ahead of the
front as low level hodographs are a little less favorable, but still
a few rotating storms would be possible in this shear environment.
Again, all of this is conditional upon the convection getting going
better as the HRRR would suggest.
A look at soundings does show a limiting factor to the depth of the
convective potential around 700mb, which will likely be a limiting
factor for deeper convection and the ultimate reason why there isn`t
more of a severe risk depicted by SPC. Nevertheless, higher momentum
air aloft could be brought down with any more robust updrafts.
.Long Term...(Saturday night through Friday)
Issued at 201 PM EST Fri Jan 1 2021
Widespread precipitation will move into the region tomorrow night as
a negatively tilted shortwave trough swings into the lower Ohio
Valley. Temperature profiles generally support an all liquid
scenario across most of central KY, but some diagnostic and ensemble
model members highlight temperatures getting cold enough to support
snow across southern IN. In the colder model scenarios, the vast
majority of snowfall accumulations are minor (<1"). The trough
should lift northeast of the region by Sunday morning, though
lingering low level moisture could result in periods of drizzle and
clouds through a good portion of the day.
Most of early next week will feature dry weather as an upper level
ridge advances from the west and keeps the region confined to dry NW
flow aloft. It`s not until late Wednesday into Thursday that the
next chance of precipitation arrives ahead of an upper level low.
Long range guidance varies on the timing and evolution of this low
over our region, which isn`t too surprising considering it`s +150
hours out. Given the variability, will keep the PoP chances low, but
think at some point in the late-week period several locations
will have a decent shot at observing precipitation.
.Aviation...(00Z TAF Issuance)
Issued at 630 PM EST Fri Jan 1 2021
Still have a few wind gusts at the terminals this evening, as a
complex low pressure system crosses the area. One lobe of that
surface low is roughly north of FFT now and continuing
northeastward. Low clouds will fill in overnight, as winds start to
die down and become variable. Subsidence moving overhead likely will
force some drizzle to develop withing the LIFR to IFR cigs expected
by daybreak in the I-64 terminals. BWG could get some as well around
daybreak, but at the least they should have less than 2 kft MVFR by
then. Conditions will be slow to improve Saturday.
Updated for 00Z Aviation Forecast Discussion below.
.PREV DISCUSSION... /issued 336 PM CST Fri Jan 1 2021/
A blustery New Year`s Day across the Mid-South. Latest surface
analysis places two areas of low pressure north of the Mid-South.
One is just east of Saint Louis, Missouri and another low near
Fort Knox, Kentucky. This has kept a stout pressure gradient over
the region, with gusts to 30 mph throughout the day. Both areas of
low pressure are expected to lift north away from the Mid-South
over the next several hours, with winds relaxing by this evening.
A cold front currently extends southward through Centerville,
Tennessee from the latter low pressure system. Temperatures have
generally fallen throughout the day as cold air has filtered in
behind the front. The exception was near the Tennessee River,
where temperatures rose into the upper 60s under mostly sunny
skies in the dry slot. The rest of the area is in the mid to upper
40s under overcast skies. Expect stratus to remain over the
region overnight, keeping air temperatures from falling too much.
Lows will bottom out in the mid to upper 30s due to moderate CAA.
A clipper type system will push through the region tomorrow
afternoon. This will keep abundant cloud cover over the region
along with the chance for light rain along and north of I-40
Saturday afternoon and early evening. QPF totals look to remain
light, less than a tenth of an inch, as temperatures fall into the
upper 30s tomorrow evening. Soundings suggest that a light rain snow
mix could occur in the Missouri Bootheel as the system lifts
north tomorrow night. No impacts are expected due to warm surface
Clear skies will finally return to the Mid-South on Sunday as
surface high pressure builds in from the west. Expect seasonal
highs with readings in the upper 40s. Dry and sunny conditions
will persist across the region through Wednesday as high pressure
remains over the region. Highs will creep into the mid to upper
50s each day. Rain will return to the Mid-South Wednesday night
into Thursday as a low pressure system moves across the Lower
Mississippi Valley through late week.
A challenging ceiling forecast, with a moist, relatively well-
mixed layer below FL030, as depicted on the RAP and NAM Bufr
An upstream upper low will lift out of the southern plains into
the Ozarks late tonight and Saturday. Scattered -RA and patchy -DZ
ahead of the low will drive a marginal IFR potential, mainly
after 12Z. SREF depicts IFR potential at MEM peaking at 30% 15Z,
decreasing to around 10 percent at 21Z. 00Z TAF didn`t depart much
from this scenario.
Area Forecast Discussion
National Weather Service New York NY
943 PM EST Fri Jan 1 2021
A warm front will approach from the south and enter the area
late tonight, followed quickly by a cold front from the west.
The low will move into New England on Saturday, followed by high
pressure building from the west Saturday into Saturday night.
Another low will develop to the south Sunday and pass to the
east on Monday, followed by high pressure building from the west
through the end of next week.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Parent low pressure tracking towards Lake Erie with secondary
development occurring along warm front to our south across the
Delmarva. The steadiest precipitation has been generally across
the southern half of the region. There is a bit of a dry slow
between precip across upstate NY and the precip closer to the
warm front. HRRR and the latest NAM show this should fill in a
bit over the next few hours. Freezing rain has been observed
across the NW interior with several locations in Orange county
measuring under a tenth of an inch of ice accretion. Early
sleet reports were brief and at the onset. Precip has struggled
to make into across eastern CT due to earlier surface ridging,
but there could be some sleet at the onset as well.
Have left the Winter Weather Advisory alone for now, although it
is possible portions of eastern CT can be removed earlier as
temperatures have been running a bit warmer. If steadier precip
can develop here, then some wet bulbing may occur allowing for
more widespread freezing rain.
Closer to the coast, plain rain, moderate at times continues.
The overall precip shield should advance eastward early Saturday
morning with drying conditions from west to east just before day
break. The secondary low may track along the warm front across
Long Island around day break. This will allow temps at the
coast to rise, and may reach the lower 50s across eastern Long
Island by daybreak.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Gusty west winds (25 to 35 mph) will develop behind the system
on Saturday as a secondary low deepens off the New England
coast. Skies will also clear in the afternoon as high pressure
builds in from the west. Deep mixing, weak CAA, and downslope
flow will result in temps above seasonable (upper 40s to mid
High pressure builds across the area Saturday night with lows
30-35 invof NYC and in the 20s elsewhere.
.LONG TERM /SUNDAY THROUGH FRIDAY/...
The main fcst challenge is the Sun/Mon sys. Low pres is progged to
deepen off the Delmarva on Sun, then track e of Cape Cod by 00z Tue.
The low is not progged to be very deep, around 995 mb in the GFS at
00Z Tue, so the storm may not get wrapped up until it is past the
area. The track is somewhere invof the benchmark, with the ECMWF e
of the GFS. If there was an arctic airmass in place, it would be a
widespread snowfall event, but that is not the case. The challenge
will therefore once again be where the rain/snow line sets up and
snowfall intensity, which will lead to eventual accums. Best spots
for all snow across the interior, and this is reflected in the storm
total snowfall. If this sys maintains an ern track however, the
heaviest pcpn may fall closer to the coast, mainly in the form of
rain. If the low intensifies a little quicker, there could be better
chances for snow closer to the coast. A model consensus was used for
the fcst attm, with thicknesses derived from the NAM and GFS. Please
see the storm total graphic for fcst accums.
Fair wx is then fcst Tue thru Fri with the area wedged between high
pres to the west, and low pres to the east. The models show a hint
of sct-isold shsn/shra late Tue into Wed with the passage of an h5
low, but the NBM pops were dry so did not include in the fcst this
There is a low pres sys modeled to pass south of the region during
the end of the week. Both the ECMWF and GFS have it. The fcst has
been kept dry consistent with the current progs, but it will be
something to watch.
Temps on Sun and Mon close to a raw model consensus for the
passing low, then close to the NBM thereafter.
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Low pressure and its associated frontal system approach from
the south tonight. The low pressure system moves across the
region Saturday morning, moving off the New England coast
Saturday afternoon. High pressure builds from the west Saturday
NE-E winds generally 10 kt or less tonight. Winds will shift to
the W-SW and increase Saturday morning with gusts 25-30 kt
likely late morning into the afternoon. Winds then become NW and
slowly weaken in the evening.
Conditions continue to deteriorate in mainly light rain, but
moderate rain is possible at times. At SWF, -FZRAPL is likely,
becoming plain rain 05-07z. A glaze of FZRA is likely at SWF
tonight before becoming plain rain.
Flight categories will continue to lower to IFR through 05z.
Widespread LIFR is forecast after midnight through around
daybreak Saturday before lifting to MVFR then VFR through the
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments likely for flight categories through early Saturday
morning. Timing of wind shift and gusts Saturday morning may be
off 1-3 hours.
.OUTLOOK FOR 00Z SUNDAY THROUGH WEDNESDAY...
.Saturday Night...VFR. NW Winds diminish.
.Sunday-Sunday Night...IFR or lower developing in rain for
city/coastal terminals and snow inland. NE wind gusts 20-25kt
near coast late Sunday into Sunday night.
.Monday...Becoming VFR. NW gusts 15-20 kt possible.
.Tuesday-Wednesday...VFR. NW gusts 20-25kt possible.
SCA conds should develop on the ocean E of Moriches tonight in
SE flow between departing high pressure and an approaching warm
front/weak low. A cold front should quickly follow by daybreak
Sat, with minimal 35-kt gales on the ocean E of Fire Island
Inlet by late morning or afternoon, and SCA conds on all other
waters as winds gust to 25-30 kt.
SCA conds with W winds gusting 25-30 kt should continue on the
ocean/bays/ern Sound into Sat evening, then ramp down briefly
overnight Sat night.
A SCA will likely be needed Sun and Mon on the ocean. Low prob for
gale force gusts. A SCA is possible for the remaining waters.
Winds and seas look to remain at mrgnl SCA lvls on the ocean Tue
thru Thu, with the protected waters blw criteria.
No hydrologic impacts are expected with one half to three
quarters of inch of liquid equivalent through Saturday morning.
Potential for another 1/2 to 1 inch of rain Sunday into Sunday
Night. Hydrologic impacts look minor at worst at this time.
Potential for minor coastal flood impacts during the Sun
morning/aft and night high tides with E/NE winds associated
with a coastal low passing to the south and east. As little as 1
1/2 to 2 ft of surge needed to reach minor flood levels during
the Sunday daytime high tides.
CT...Winter Weather Advisory until 4 AM EST Saturday for CTZ005>008.
NY...Winter Weather Advisory until 4 AM EST Saturday for NYZ068>070.
Winter Weather Advisory until 7 AM EST Saturday for NYZ067.
NJ...Winter Weather Advisory until 4 AM EST Saturday for NJZ002.
MARINE...Small Craft Advisory from 9 AM to 7 PM EST Saturday for ANZ335-
Small Craft Advisory from 9 AM Saturday to midnight EST
Saturday night for ANZ330-340-345.
Small Craft Advisory from 6 AM to noon EST Saturday for ANZ353.
Gale Warning from noon to 7 PM EST Saturday for ANZ353.
Small Craft Advisory from 6 AM Saturday to midnight EST
Saturday night for ANZ355.
Small Craft Advisory until 6 AM EST Saturday for ANZ350.
Gale Warning from 6 AM to 7 PM EST Saturday for ANZ350.