Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/10/18
Area Forecast Discussion
National Weather Service Boston/Norton MA
958 PM EST Fri Nov 9 2018
An intensifying storm tracks over the the Cape Cod Canal tonight.
This system will bring moderate to heavy rains, potential flooding,
and possible strong to damaging winds. Dry and unseasonably chilly
temperatures follow Sunday into Monday. Another low pressure will
bring a period of heavy rain to the region late Monday night into
Tuesday, but there is a low risk for precipitation to begin as a
brief period of snow or ice across the interior. Dry but unseasonably
cold weather follows Wednesday into Thursday, before temperatures
moderate some by Friday.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
10 pm update...
- Flood Watch trimmed to focus on E / SE New England into
- Wind Advisory for Cape and Islands continues
- Monitoring convection / heavy rain closely S of LI approaching
SE New England, likely impacting shortly after midnight into
early morning Saturday.
Secondary low strengthening S of Long Island with observed pressure
falls around 2 mb / hr. Providing a localized convergent focus of
the warm-moist conveyor belt beneath broader diffluence aloft,
seeing heavy rain and convective elements emerge. Strong SW 0-6 km
shear and mean wind, line echo wave patterns emerging as discerned
via WSR-88D. MRMS interpreted 1-hour rainfall rates of 0.5 to 1.0
inch given the progressive nature of the storm system. Storm system
should lift NE through tonight at a rapid pace, exiting close to
early morning Saturday. Heavy rain and damaging wind threats continue
which are highlighted below.
Focus ahead of the secondary low within the weak warm sector, marginal
lapse rates. A focus on H95 winds. Will hold with the present wind
advisory however there is some concern that even S areas of Bristol
and Plymouth Counties in MA could reach wind advisory criteria if
heavy rain is able to drag down faster momentum. S gusts upwards of
50 mph continue into early morning with the possibility of a quick
SW burst immediately behind the secondary low as both pressure
gradient and isallobaric forces advect colder air rearward allowing
steep lapse rates and that opportunity for a quick mix down of
faster momentum. Hence keeping the WIND ADVISORY for the Cape and
Islands extended through Saturday. GALE WARNINGS for all waters
throughout as well.
H95-925 SE jet centered around 1 am over SE New England, especially
Cape Cod and Islands with values over 55 to 65 mph. It`ll be
interesting to see how much of this momentum will mix down to
Significant WSR-88D radar returns approaching from the SE out ahead
of the secondary surface flow. Coupled pressure falls with anomalous
precipitable waters upwards of 1.5 - 1.7 inches per latest RAP / SPC
mesoanalysis, both the H925-85 moisture transport aimed at SE New
England, trimmed the FLOOD WATCH to SE New England highlighting the
region of greatest confidence for flooding rains. To the W, mid-
upper level drying along with subsidence between the double-barrel
low is contributing to a quick end to the rainfall over the NY
Hudson Valley extending into W New England. Collaboration with other
WFOs, watch was dropped W of the I-95 corridor.
Column saturation up to 12 kft per latest RAP, deep column ascent
given dynamics out ahead of the potential vorticity displacement
along the 1.5 PVU surface, potent vortmax and accompanying diffluence
aloft, undoubtedly some efficient rainfall production will occur
over SE New England.
Urban / poor drainage flooding, especially more so with leaf-clogged
drains. Potential flooding of faster responding small streams and
tributaries. Rivers running high as of late, so this water being
added to the system will only exacerbate and/or prolonged any
ongoing or forecast river flooding issues.
Quick 1 to 2 inches, locally higher amounts. Greatest amounts focused
in and around the Cape Cod Canal immediately E of the low track.
CONCLUDING REMARKS ...
With respect to emerging convection ahead of the secondary low, there
is some concern for localized severe weather. Can`t rule out a brief
tornadic spin-up through the greater confidence is out over the warmer
waters further S/E. There`s a lot of helicity in the region in addition
to low-level shear. If the lapse rates can steepen more than just
marginal, then the damaging wind potential greatly increases. Watching
closely for bowing segments within the line echoes that are approaching,
looking for any potential book-end vorticies that may emerge in the
NE quadrant of any bowing. Will handle any convective elements with
short-fused severe / special marine warning products.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
- Wind Advisory for central/eastern MA and RI with Westerly gusts
45 to 50 mph.
- Flood Watch continues into Sat with the likelihood of some area
rivers and streams continuing to rise in the wake of the Fri
The low pulls rapidly northeastward and away from southern New
England during Saturday morning, steadily deepening along the
way. Negatively tilted upper trough sweeps thru southern
Quebec/northern New England with an associated short wave
pushing thru our area. This accompanied by cold air advection
and tight pressure gradient with departing low result in the
potential for a secondary W wind burst. Models show steep low
level lapse rates to H85/H7 which would enable mixing of
stronger winds aloft to the surface. Anticipating Wind Advisory
event over a portion of southern New England with gusts 40-45
kts. Have issued a Wind Advisory for RI and central/eastern MA
for Saturday 10 am to 7 pm.
*/ Precipitation / Flooding...
Could still have some patchy light rain lingering at daybreak,
possibly a light snow shower across the highest terrain of Franklin
County MA. Looking at model soundings, quite a dry airmass in
place but given steep low level lapse rates, can`t rule out an
isolated shower or 2, or even a few flurries over the far
Otherwise mainly dry day in store. However Flood Watch continues
into Saturday, as some area rivers and streams will likely still
be rising from the very recent rains.
High temps for the day will probably occur in the morning for some
locales, especially eastern MA and RI. Temps falling in the
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
* Dry/unseasonably chilly Sun into Mon afternoon
* Period of heavy rain/renewed flooding concerns late Mon night/Tue
with a low risk for a brief period of snow/ice at the onset across
* Dry but unseasonably cold Wed/Thu with some moderation by Fri
Dry, but breezy to windy weather will continue Sat night in the cold
air advection pattern. Bufkit soundings continues to support
excellent mixing...so 25 to 40 mph wind gusts will continue well
into the evening. Low temps will bottom out mainly in the middle
20s to the lower 30s...but it will feel colder given the winds.
Sunday and Monday...
Dry but unseasonably chilly weather will continue Sun into Mon
afternoon as high pressure builds in from the west. High
temperatures on both days will be only in the 40s. The colder/more
breezy day will be Sun and its possible that portions of the
interior high terrain does not break 40.
Monday night and Tuesday...
There continues to be excellent model agreement in an intensifying
low pressure system working northward from the mid Atlantic states.
The track/timing/strength of this low pressure system remains
uncertain given this is 4 days in the future. The lack of downstream
blocking or a strong Canadian high pressure system strongly favors a
rain event...but a bit of snow/ice can not be ruled out at the onset
across the interior. While the system will be progressive...a
period of heavy rain is certainly possible with a general 1 to 2
inches of rain. Therefore...we will need to watch for renewed
river/stream flooding given some MMEFS projections based on the very
wet weather we have had of late.
Wednesday through Friday...
Deep upper trough setting up across New England will result in dry
but unseasonably cold weather Wed into Thu. Low temps mainly be in
the upper teens and 20s with highs mainly in the upper 30s to the
lower 40s. It will also be quite windy Wed. High pressure will
move off the coast Fri...resulting in some moderation in
temperatures. Appears mainly dry weather will likely persist.
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Saturday/...Moderate to high confidence.
Widespread low end MVFR-IFR conditions in rain with brief LIFR
conditions possible in the heaviest rain. Low risk for an isolated t-
storm or two. LLWS expected...but brief burst of strong southerly
winds between 35 and 45 knots should be confined to the Cape/Islands
in the warm sector later tonight. Worst conditions with respect
to winds and LLWS centered 3-9z.
CIGS improving to VFR or high MVFR to start the day,then clouds
scattering out midday-aftn. No VSBY issues. Winds quickly shifting
W, then increasing through the day, widespread 35 to 40 kt gusts
especially afternoon into evening.
KBOS Terminal...Moderate to high confidence.
KBDL Terminal...Moderate to high confidence.
Outlook /Saturday Night through Wednesday/...
Sunday Night through Monday: VFR. Breezy.
Monday Night: Mainly VFR, with areas MVFR possible. Breezy. RA.
Tuesday: Mainly IFR, with areas MVFR possible. Strong winds
with gusts to 45 kt. RA.
Tuesday Night: Mainly VFR, with areas MVFR possible. Windy with
areas gusts to 30 kt. Chance SHRA.
Wednesday through Wednesday Night: VFR. Windy with gusts to
Thursday: Windy with local gusts to 30 kt.
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Saturday/...High confidence.
Stout area of low pressure sweeping NE over the Cape Cod Canal
shortly after midnight Saturday. S/SE gales forecast with the
potential for 45 kt gusts especially near S/SE coastal New England.
Wind direction will veer over time as the Gale center tracks over
the coastal waters. Wave heights building 9 to 11 feet along the
outer coastal waters. Moderate to heavy rain developing during this
evening and lasting into early Saturday morning, embedded
thunderstorms possible, and likely visibility issues on the waters.
Storm force winds possible with heavier rain and/or thunderstorms
that may require Special Marine Warnings.
During early Saturday morning the low pressure lifts NNE into the
waters off the coast of Maine. Winds over the S. New England coastal
waters are out of the W/WSW for the day. Increasing winds during the
day with likely 35 to 45 kt gusts over all waters developing by
afternoon and lasting thru the remainder of the day.
Outlook /Saturday Night through Wednesday/...
Sunday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of seas approaching 5 ft.
Monday: Winds less than 25 kt.
Monday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas locally approaching 5 ft. Rain.
Tuesday: Moderate risk for gale force winds with gusts up to
45 kt. Rough seas up to 14 ft. Rain. Visibility 1 to 3 nm.
Tuesday Night: Low risk for gale force winds with gusts up to
35 kt. Rough seas up to 14 ft. Chance of rain showers.
Wednesday: Moderate risk for gale force winds with gusts up to
40 kt. Rough seas up to 12 ft. Slight chance of rain showers.
Wednesday Night: Low risk for gale force winds with gusts up to
35 kt. Areas of rough seas.
Thursday: Moderate risk for Small Craft Advisory winds with
local gusts up to 30 kt. Local rough seas.
CT...Flood Watch through Saturday afternoon for CTZ004.
MA...Wind Advisory until 7 PM EST Saturday for MAZ022>024.
Flood Watch through Saturday afternoon for MAZ005>007-012>021.
Wind Advisory from 10 AM to 7 PM EST Saturday for MAZ004>007-
Flood Watch until 5 AM EST Saturday for MAZ022.
RI...Wind Advisory until 7 PM EST Saturday for RIZ008.
Flood Watch through Saturday afternoon for RIZ001>007.
Wind Advisory from 10 AM to 7 PM EST Saturday for RIZ001>007.
MARINE...Gale Warning until 7 AM EST Sunday for ANZ231>235-237-251.
Gale Warning from 10 AM Saturday to 7 AM EST Sunday for ANZ230.
Gale Warning until 4 AM EST Sunday for ANZ236.
Gale Warning until 9 AM EST Sunday for ANZ250-254>256.
Area Forecast Discussion
National Weather Service Caribou ME
1040 PM EST Fri Nov 9 2018
Low pressure will approach from the southwest overnight and
cross the area Saturday. The low will intensify in the Maritimes
Saturday night into Sunday and bring strong winds into the
.NEAR TERM /THROUGH SATURDAY/...
1040 PM Update...Adjusted hrly temps to match up w/the latest
conditions. Still seeing low to mid 30s across the north while
central and downeast areas were seeing upper 30s to lower 4Os.
temps will drop off overnight as precip moves in. The latest
trend of the regional radar showed reflectivity increasing
across the srn and coastal areas w/rain being reported. Further
n, llvls still dry given the mid level deck in place. The latest
RAP soundings show llvls to moisten quickly w/temps dropping
back to AOB 32F leading to snow to develop. Decent mid level
forcing advertised by the RAP and 00Z NAM to lead to some heavy
snowfall w/snowfall rates 1 to 2 inches per hour. SPC issued a
MCD illustrating this potential. Could see a brief period of
snow across the Bangor region before a changeover to rain.
Speaking of the rain, llvl convergence and forcing will allow
for some heavy rainfall across the Downeast region overnight.
The current Winter headlines remain in place. Midnight crew may
need to expand the Winter Weather Advisory for central areas
such as Dover-Foxcroft into Lincoln as cold air could hang in
longer allowing for snow to last longer before the changeover.
The deepening low will track towards the Gulf of Maine and Down
East region later overnight into Saturday. This low will
actually be close to meeting bombogenesis criteria by Saturday
night. This low...and an occluded front stretching back to a low
in Canada...will bring a period of heavy precipitation later
tonight into Saturday morning. P-type and the rain/snow line is
the first challenge for tonight. There antecedent air mass is
marginally cold, but evaporative cooling and heavy precip will
eradicate the warm boundary layer and create snow...mostly for
Piscataquis, northern Penobscot and Aroostook counties. Areas
north of a line from Dexter towards the southern border of
Aroostook County will receive at least two inches of heavy wet
snow. The best coincidence of heavy QPF and cold boundary layer
temps appears to be in central Piscataquis County and a Winter
Storm Warning has been issued for Zone 10 where towns such as
Greenville are at 1000ft elevation. Snow accumulations will be
very elevation- driven as it usually the case with early season
events. The period of snow will be rather brief with the warm
advection, but there is some instability aloft and good omega in
the DMZ for several hours. This could produce snowfall rates of
1 to 2 or even 3 inches in an hour. This means poor visibility
and quickly deteriorating roads. The late night timeframe will
mean that the snow will stick to roads. The warm nose aloft will
cause a changeover to sleet after some 3 to 5 hours of moderate
to heavy snow. The sleet won`t last more than a couple of hours
before precip winds down with arrival of the dry slot and
drizzle. The heavy wet snow could cause some power outages.
Significant accumulating snow will be over by early Saturday
morning and temperatures will exceed the freezing mark and
promote melting. Temperatures will actually reach the low to mid
50s in coastal Washington County where the frontal inversion
breaks. The warming will be relatively short-lived as a cold
front crosses in the afternoon. The front will provide another
burst of precipitation...mostly towards northern Aroostook and
possibly some wind gusts of 40 to 45 mph as it crosses with some
power outages possible. There are some similarities with last
Saturday`s cold front with strong winds aloft...upper jet and
sharp shortwave trough. Temperatures will fall very quickly
behind this front with some icy surfaces possible again by
evening. Not a flash freeze...but still a concern. The bombing
low pressure and tightening pressure gradient will then start to
bring some very strong wind gusts with strong cold air
advection and mixing by late day.
Towards the coast, there will some heavy rain tonight, but not
enough to prompt flooding concerns, outside of some
ponding...potentially helped by leaves clogging drains. Strong
wind gusts up towards 40 mph are possible late tonight...with
momentum transfer from a strong LLJ just offshore. Winds will
return late day with the aforementioned cold front.
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
By the start of the short term sfc low wl be north of the Gulf of
St. Lawrence with wrly winds increasing drg the overnight. Strongest
low level winds acrs the area look to be in the 03z-12z Sun
timeframe with wind gusts on the order of 30-45kts acrs the highest
terrain. This appears to fall strongly in the wind advisory criteria
for all areas.
Scattered-isold snow showers wl rmn acrs nwrn zones Sat night as upr
low pulls into the Canadian Maritimes with nw flow in its wake.
Expecting less than an inch of accumulation thru the nighttime hrs.
Cold advection with H9 temps dropping to nr -10C by daybreak wl
allow temps to dip into the 20s acrs all areas. Highs on Sun wl
struggle to rebound into the 30s acrs the north. Skies wl be moclr
Sat night and mosunny on Sunday while stratocu still lingers ovr nrn
areas into Sun aftn.
High pressure builds off the east coast Sun night with ridging
relaxing pressure gradient Sun evening. Ridge axis wl bisect CWA Mon
aftn. Temps on Mon morning wl start off in the teens in most
locations with highs drg the day vry similar to Sunday`s highs,
some 10-15 degrees blo normal.
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Upr lvl trof dropping into the srn Plains wl induce cyclogenesis
acrs the northern Gulf of Mexico on Monday. As this system exits the
southeast on Tue morning it wl bring pcpn back into the area late
Mon night with stratiform pcpn occurring all day on Tue. Track of
the sfc low wl determine ptype with GFS hugging the coast and
CMC bringing low thru cntrl portion of CWA on Tue. Euro is the
compromise. Hv followed Superblend guidance which appears to be
similar to latest Euro and is vry similar to prior fcst. Rain
looks to reach as far north as the Caribou area Tue evng bfr
colder airmass filters south and gradually switches pcpn back to
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
NEAR TERM: VFR conditions will deteriorate towards IFR to LIFR
before midnight at BGR and in the following hours at the
remaining TAF sites. Sites such as GNR, MLT and HUL northward
will have several hours of VLIFR vis in heavy snow that will
definitely affect rwy condition. There may also be a few hours
with mixed precip late tonight at BGR. LLWS is expected to be an
issue at HUL early Saturday, but could affect other sites too.
Snow will be mostly over early Saturday morning except at FVE
and the trend will be towards IFR cigs after the snow...until a
cold front arrives in the afternoon. The cold front may feature
some wind gusts towards 35 or 40 mph.
SHORT TERM: IFR expected on Sat aftn all terminals with some
improvement to MVFR over Downeast areas by late afternoon. Nrn
terminals likely to remain MVFR in stratocu into Sunday then
becoming VFR thru Mon night. Gusty west winds expected late Sat
night into Sunday morning. Next low pressure system will bring
IFR restrictions Tue morning with rain across Downeast and snow
across the north. Mixed precipitation moves to the north by Tue
NEAR TERM: The Gale Warning continues to look solid for tonight.
There will be a brief respite in the winds during the morning
and they will increase with a vengeance during the afternoon on
the backside of the low. These winds will be northwesterly.
SHORT TERM: Gales will continue through Sunday, especially on
the outer waters. Inner bays will likely relax to strong SCA
wind gusts in the afternoon. Seas 5-10 feet into Sun morning in
serly swell before dropping blo 5ft Sun night. Wind gusts to
remain around SCA levels into Sun mrng before relaxing as high
pressure crosses the waters.
ME...Winter Weather Advisory until 1 PM EST Saturday for MEZ001>006-
Winter Storm Warning until 1 PM EST Saturday for MEZ010.
MARINE...Gale Warning until 5 PM EST Sunday for ANZ050>052.
Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
823 PM CST Fri Nov 9 2018
Overall the short term forecast remains in good shape. I did make
a few slight changes to overnight temperatures, which necessitated some
slight alterations to the ongoing Freeze Warning. Otherwise, the
remainder of the forecast remains unchanged.
Dry air continues to filter in across North Texas this evening as
surface high pressure slides eastward into the Ozarks. H925 flow
should gradually slacken and with dry conditions, boundary layer
decoupling should ensue across most of the area---despite the
upper level cloud cover. Dewpoints and temperatures were running
generally 2-4 degrees below some guidance and the previous
forecast. The LAMP and HRRR offer reasonable solutions for hourly
and min temperature values. With this in mind, it appears that
areas near I-20 may be exposed to a least an hour or two of sub-
freezing conditions and I appended a handful of counties to the
previous Freeze Warning as a result.
Inside the heart of the D/FW Metroplex, temperatures may only
near 33-34 degrees, with less urbanized areas of Dallas, Tarrant
and Rockwall counties likely falling to 31 to 32 degrees.
Regardless, if you have any doubts about protecting sensitive
vegetation---it may not be a bad idea to cover them or move them
inside. In addition, check on pets and disable automatic sprinkler
systems. Outlying areas east of D/FW should also have a decent
chance to see temperatures at or below 32 degrees, though far
reaches of Van Zandt County may stay closer to 33 degrees as 925mb
flow may be a bit brisker due to the slightly tighter height
gradient on the periphery of the low level ridge. I added Eastland
County, mainly for local effects as low- lying and sheltered
regions should easily fall into the low 30s (some sites are
already in the upper 30s). There will be a potential for some
frost, but overall temperature- dewpoint spreads seem a bit on the
marginal side to include in the official forecast. For now, we`ll
continue to talk this up in graphics.
I also added some silent 10s across Central Texas where some
meager ascent continues to overspread the area. The 00 UTC FWD
RAOB may have sampled a slightly drier airmass here across North
Texas compared to farther south, but it`s unlikely that we`ll see
any measurable rain. Still, a sprinkle or two cannot be ruled out
near and south of a Comanche to Hillsboro to Athens line.
The rest of the forecast is in good shape and updated products and
hazards have been shipped.
.AVIATION... /Issued 552 PM CST Fri Nov 9 2018/
00 UTC TAF Cycle
Concerns---None major. VFR with northerly winds becoming easterly
VFR will prevail at all North and Central TX terminals through
early Sunday morning. Northerly winds will subside tonight with
speeds falling to or below 10 knots. There could be some patchy
frost on aircraft that remain idle overnight into Saturday morning
at area terminals, but the large temperature/dewpoint spread may
preclude a more appreciable threat. Northerly winds will become
easterly through Saturday morning with a possible return to south
flow by the noontime hour on Saturday. High clouds will persist
with cigs lowering into the FL070-FL100 range late Saturday
.SHORT TERM... /Issued 350 PM CST Fri Nov 9 2018/
Brisk north winds continue ushering in unseasonably cool/dry air.
Even with abundant sunshine, temperatures are only peaking in the
low to mid 50s this afternoon, providing a head start for the
temperature free fall tonight.
Our postfrontal surface high, now centered over Kansas, will drift
southeastward toward the Ozarks tonight. Although the core of this
arctic air will be far from North Texas, the associated ridge axis
will be draped across our northern and western zones tonight. It
is in these areas that the winds will subside more quickly this
evening, allowing temperatures to fall into the 30s before
midnight. (A few wisps of cirrus will do little to disrupt this
process.) The 850mb high will settle into our northwest zones
during the predawn hours Saturday, the reduction in momentum aloft
further enhancing the radiation from the layer beneath it. A more
steady breeze through Northeast and North Central Texas (and
considerable flow in the 925-850mb layer) will restrain the
temperature drop, and the core of the Dallas/Fort Worth Metroplex
is unlikely to see freezing temperatures of any significant
duration. As a result, a Freeze Warning will exclude the
previously watched counties of Tarrant, Dallas, Rockwall, and
Kaufman. However, the warning will be expanded in the west to
include Stephens. Based on evening trends, Eastland may need to be
added as well. For locations in the warned area, November 10 is
within a few days of the average first freeze date.
There remains some disparity among model guidance with respect to
dew points overnight. This is a critical piece of the puzzle as
lower dew points will enhance the radiational cooling while
reducing the frost potential. Even where the winds are the
lightest overnight, calm (or near-calm) conditions may not be
prolonged enough to allow ground temperatures to reach their full
radiational cooling potential. This will also limit cold air
drainage though low-lying and otherwise sheltered areas within the
Freeze Warning should still have a greater duration of freezing
temperatures. It may be that the greater potential for frost is in
areas where the official temperature (several feet above the
ground) is actually above freezing, but where the dew points are
sub-freezing without being too dry. In other words, even in areas
outside of the Freeze Warning, precautions should be taken to
protect sensitive vegetation. Assure automatic sprinkler systems
.LONG TERM... /Issued 350 PM CST Fri Nov 9 2018/
/Saturday Through Friday/
The upper pattern will remain active through early next week with
a few chances for rainfall, our first arctic intrusion into the
region, and at least a brief shot for some wintry precipitation
across the northwest.
Saturday will start off cold with many areas north of the
Metroplex to the Red River near or a few degrees below freezing
under mostly clear skies. Changes will be quick to occur though as
the surface high slides into the mid-Mississippi River Valley and
low-level flow begins to veer to the south. Strong mid-level
isentropic ascent will overspread the area from southwest to
northeast starting around midday and continuing into the evening.
We`ll see a rapid increase in mid-level cloud cover through the
day Saturday, although we should remain mostly precipitation
free. Despite the strong ascent, the layer beneath 700 mb will
remain quite dry. It`s always a little concerning when mid level
moisture becomes available within an area of lift. This can often
result in high based showers or storms in the presence of
instability. With the strongest lift quickly moving to the
northeast into Saturday evening, we`ll keep PoPs at 10% through
Saturday night should be rain free, although overcast conditions
will prevail with our moisture depth increasing under the
influence of persistent southerly flow. Temperatures will be about
5-10 degrees warmer Saturday night across the region. The upper
pattern will also begin to amplify during this time with a strong
shortwave trough digging into the western U.S.
On Sunday, with the upper trough over the 4-corners region, cold
air will begin to spill southward through the Plains and into
Texas during the afternoon. Strong low-level warm advection will
likely result in an area of showers and perhaps a few
thunderstorms mainly east of I-35 into the evening hours. This
initial wave of ascent should spread off to the northeast into the
late evening hours and we may actually see a decrease in the
coverage of precipitation prior to midnight. After midnight,
much stronger forcing for ascent associated with the approaching
upper trough will begin to spread through the Southern Plains.
Coverage of rain should increase areawide late Sunday night into
Isentropic ascent should be maximized across North Texas very late
Sunday night into early Monday morning. A deep column of saturated
air located within this area of ascent and a favorable upper jet
position should support several hours of moderate precipitation
across the region through mid-morning Monday. Surface temperatures
during this time will likely be in the upper 30s and the
prevailing precipitation type will be all rain. There will be a
brief period very early Monday morning where column temperatures
cool sufficiently, and we retain deep moisture for snow production
to occur. This is most likely to happen northwest of the
Metroplex from Gainesville to Mineral Wells to Eastland where
we`ll introduce a slight chance of snow mixed with rain. Upstream
dry air will quickly spread into the region from the northwest by
late morning effectively ending any wintry precipitation potential
through the rest of the day. Given the limited time duration in
which snowfall could occur, and well above freezing surface temps,
no significant impacts are expected.
Precipitation will quickly end from west to east during the day
Monday with highs likely remaining in the upper 30s and lower 40s.
Dry north-northwest flow aloft will prevail through the end of
next week with temperatures warming back into the 60s by Thursday.
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 32 51 42 51 41 / 0 5 10 30 60
Waco 36 52 43 52 44 / 10 10 10 50 60
Paris 29 48 39 47 40 / 0 5 10 20 70
Denton 31 51 41 51 41 / 0 5 10 20 50
McKinney 30 49 41 49 41 / 0 5 10 20 60
Dallas 32 51 43 51 42 / 0 5 10 30 60
Terrell 32 52 42 50 42 / 0 10 10 40 70
Corsicana 35 51 43 51 43 / 10 10 10 50 70
Temple 38 51 44 52 45 / 10 10 10 50 60
Mineral Wells 31 51 39 53 38 / 0 5 10 20 60
Freeze Warning from 3 AM to 9 AM CST Saturday for TXZ091>095-
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1001 PM EST Fri Nov 9 2018
Issued at 1000 PM EST FRI NOV 9 2018
Colder air continues to advect into the region, most noticeable
still on the highest ridges. Loaded in the latest observations for
temps and winds to make sure the near term forecast reflected the
ongoing conditions. NW flow is also keeping drizzle across
portions of the CWA, but with a shot of colder air moving into the
western CWA now, not surprised if some of this rain is starting to
change over to or mix in with some snow flurries. A new set of
zones was sent out to reflect overnight wording and any updates to
the weather as light precip continues to change over before
tapering off late tonight.
UPDATE Issued at 729 PM EST FRI NOV 9 2018
Rain has now exited east of the CWA with residual upslope flow and
drizzle taking hold across portions of the CWA. With the slightly
quicker exit of the precip, and the breezy NW flow, temperatures
are starting to drop, especially over the higher terrain. Based on
latest observations, higher terrain is trending down faster than
the original forecast, and will likely fall below the forecasted
low temperatures if this rate continues. Went ahead and adjusted
the temperatures during the current hour to match the ongoing
observations, then proceeded to update the hourly temps throughout
the night to show a better diurnal trend of falling temps. Also
updated the forecasted lows and highs for tomorrow as well.
Finally, adjusted pops to better reflect the current trends, with
a quicker exit of rain showers now east of the region. Reran the
weather grids based on the updated pops and temps. All updates
have been published and sent to NDFD/web. A new forecast package
will be sent out shortly as well.
.SHORT TERM...(This evening through Saturday night)
Issued at 325 PM EST FRI NOV 9 2018
19z sfc analysis shows low pressure pulling further away from the
area to the northeast. The system`s cold front is now east of the
state allowing west to northwest winds to pick up to between 5 and
10 mph this afternoon across the CWA. Temperatures are struggling
to rebound much today in the face of this cold air advection.
Accordingly, readings range from the lower 40s in the northwest to
the mid 40s in the southeast. Dewpoints are just a couple of
degrees below dry bulb temperatures most places. The main area of
rain showers is slowly progressing east on radar with a back edge
currently from West Liberty southwest to near London. Likely some
light rain or drizzle follows this rain under overcast skies. Some
patchy fog remains around accompanying the rain - mainly on the
The models are in pretty good agreement through the short term
portion of the forecast. They all depict the bottoming out of a
fairly deep trough over the Great Lakes tonight with troughing
passing through the Ohio Valley along with a 300mb jet streak.
This feature then lifts out of the area on Saturday relaxing the
lower heights over Kentucky but maintaining the fairly fast flow
in its wake along with ample amounts of energy through midday.
This mid level flow becomes southwesterly later Saturday into
Sunday morning with weaker energy packets running overhead during
this time. Given the model agreement have favored a general blend
with a strong lean toward the HRRR and NAM12 for details.
Sensible weather will feature the bulk of the rain exiting by
early evening though a few pockets of sprinkles and light rain
will trail behind. Colder air will keep getting pulled into the
area on northwest winds through the evening and overnight so that
any lingering showers could transition to snow showers from west
to east through the middle part of the night. The 5h trough
digging past to the north will likely enhance these showers a bit
despite an overall drying trend - along with the upslope flow - to
maintain the snow shower threat into dawn for the eastern portion
of the state. Still believe that the warm ground temperatures
will limit any dustings to elevated surfaces and on the grass into
Saturday morning. Further drying will likely cut off any
lingering snow showers and flurries by mid morning. One small
concern during this transition time will be the potential to lose
ice crystal formation for a time during the early morning hours
that could lead to pockets of freezing sprinkles or drizzle
- but most places will be able to go over to scattered snow
showers without any freezing pcpn. Will limit the mention of this
possibility to the HWO for now and allow subsequent shifts
evaluate the potential for limited icing and/or a dusting of snow
in the far east. Some sunshine returns by Saturday afternoon,
though temperatures will be hard pressed to climb out of the 30s
with light northwest winds adding to the chill. Clear skies and
high pressure passing through on Saturday night will set up a very
cold night with some readings in the upper teens possible for
sheltered valleys by dawn.
Used the CONSShort and ShortBlend model guidance as a starting
point for all the grids. Adjusted temperatures Saturday night to
add in more of ridge to valley split through dawn Sunday. As for
PoPs did linger them longer for the higher terrain in the far east
through the night and into Saturday morning. Did also minimize
the freezing rain potential by increasing the ProbIce grids to
near 100 percent late tonight.
.LONG TERM...(Sunday through Friday)
Issued at 250 PM EST FRI NOV 9 2018
The extended period will feature a period of wet and active weather
sandwiched by periods of quiet and dry weather across eastern
Kentucky. The period should start off dry, albeit still much cooler
than normal, on Sunday, as a ridge of high pressure remains
entrenched across the region. The ridge will eventually begin to
break down and move off to our east late Sunday night into early
Monday morning, as a strong area of low pressure begins to invade
the region from the south. The latest model data continues to
support this scenario.
This area of low pressure is forecast to move across the Gulf Coast
region and eventually across the southeastern CONUS and then up the
east coast Monday and Tuesday. This system will bring a combo of
rain and snow to eastern Kentucky Monday night and Tuesday. The
latest model data is suggesting the possibility of light snow
accumulations Monday night into Tuesday morning, especially along
and west of a line from Inez to Jackson to Williamsburg. Their
continues to some differences amongst the various models regarding
timing of the weather system across the area, precipitation onset,
and duration of any snow fall. The general trends that are being
observed at this time are for the snow to penetrate a bit further
east into the forecast due to cold air progressing a bit further
south and east than previously thought. However, due to the amount
of uncertainty that still exists in the models, we will continue to
take this situation with a grain of salt, at least until the models
hone in more on a common solution. This weather system is currently
being forecast to exit the area, along with all its precipitation
early Tuesday night. A large area of high pressure is then forecast
to settle over the region on Wednesday, and may remain in place
through the end of the week. Should the model data prove correct,
this will be the coldest air we will have seen across eastern
Kentucky so far this season.
Temperatures will continue to run well below normal during the
period, with daily highs in the 30s, 40s, and 50s expected. Nightly
lows will run from the upper teens to the mid 30s. The coldest
period will be the Tuesday through Thursday time frame. Highs on
Tuesday are expected to range from the upper 30s to lower 40s, with
lows on Wednesday likely not making it out of the 30s for most
locations. After the area of low pressure finally exits the area
Tuesday night, a strong ridge of high pressure will usher in the
coldest air of the season for the middle of the week.
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 738 PM EST FRI NOV 9 2018
The surface cold front that impacted the region today has now
moved east, with high pressure moving in from the west. Moist
llvls and northwest flow is now leading to drizzle across portions
of the region, with some of the highest peaks across eastern KY
possibly seeing a changeover to flurries as temps fall below
freezing. VIS has improved to VFR with the exit of the rainfall,
and CIGS are continuing to improve as well, generally between MVFR
and VFR. Continued cloud cover and breezy winds will likely
prevent fog formation overnight. Expect CIGS to continue lifting
and improving throughout the overnight, with mostly clear skies
expected during the day Saturday as the are of high pressure moves
across the state. Winds will also become light and variable
during the day tomorrow as a result.
Area Forecast Discussion
National Weather Service Paducah KY
800 PM CST Fri Nov 9 2018
Issued at 800 PM CST Fri Nov 9 2018
A low-topped line of snow squalls continues to march southeast of
the St. Louis metro area this evening. There has even been some
thunder observed in the squalls, which reduced vsby to 1/4 mile in a
few spots. A narrow but well-defined trough of low pressure
accompanies this line, followed by a few hours of strong northwest
winds gusting up to 35 to 40 mph.
The driving force for the snow squalls appears to be steep low-level
lapse rates along the arctic cold front. Model soundings from the
rap indicate lapse rates will slowly weaken ahead of the front. The
line will also be moving into slightly drier air. There are already
some indications the line is decreasing in width. The current
forecast appears to have these trends covered well. A brief burst of
heavy snow is likely in the advisory area this evening. The main
impacts will be from low visibility and gusty winds, as opposed to
hazardous road conditions. There will be some slick spots, mainly on
bridges and overpasses. Little if any snow shower activity is
expected in southwest Kentucky, where drier and more stable air will
be hostile to the convective snow showers.
.SHORT TERM...(Tonight through Sunday night)
Issued at 308 PM CST Fri Nov 9 2018
Transition to an winter weather advisory event made this
afternoon for a few counties along Interstate 64 in southern
Illinois. In previous forecasts have hinted at a rain/snow to snow
mix in southern Illinois and southwest Indiana, but refining the
timing and placement of mesoscale wintry system has not been
attainable until now.
The main challenge with the system has been the degree of
intrusion of drier air from the southwest, limiting the effective
coverage of ice nucleation in the preferred snow growth layer.
However, the sharp intensification of the closed low over
Wisconsin, the deepening of the baroclinic zone (channeled
vorticity arcing down through central Illinois between 21z (3 pm)
and 03z (9 pm)) should support more significant lift, compensating
for the less than ideal moisture.
With emphasis toward the RAP numerical guidance as a proxy for
other high resolution guidance, the northern end of the WFO PAH
forecast area (Interstate 64 corridor) will slowly move away from
the favored right exit region (corridor of 125-130 knot winds) of
the 300 mb jet axis, but the proximity of another jet max further
south may still sustain broad lift into southwest Indiana and
Maximum wet bulb through the 0-6km layer rapidly move from zero
to minus 3 degrees Celsius during the evening hours, while the
surface wet bulb temperatures drop into the 30-31 degree range in
advisory area. Upper level divergence is maximized over southeast
Illinois and southwest Indiana between 02z-05z this evening. The
I-64 corridor is on the very edge of the greatest vertical motion
in the snow growth layer.
At the surface, there will be a tight pressure gradient between
the high pressure surface in eastern Kansas and the surface low in
in the upper peninsula of Michigan. This pressure gradient,
combined with vertical mixing with the quick moving system
tonight, will generate wind gusts averaging around 25 mph over
southern Illinois, southwest Indiana, and northwest Kentucky. This
may cause issues for travelers tonight and help to accelerate
transfer of colder air into the region.
At this point in time, concerned that snowfall rates may exceed
the ability for ground and road surfaces to melt adequately for an
hour or less in the advisory area. This may also reduce
visibilities over short distances, creating hazardous travel
conditions in the advisory area this evening. An winter weather
advisory was issued for the area expecting the most impact, then
surrounded with a Special Weather Statement for adjacent counties
south and east of the advisory area that may see lesser impact
Recent numerical model trends continue to support low to middle
20s for lows tonight and Saturday night, with highs mainly in the
30s on Saturday. There is expected to be a slight recovery in
temperature on Sunday into the 40s, before the next system moves
into the area early next week.
Leaned closer to the Canadian (CMC) and NAM-WRF (ARW version) for
dewpoints through this weekend, blended with short term model
blends. Utilized the NAM-WRF, NAMNest, RAP, and ESRL HRRR guidance
for the timing of this evening`s system, temperature, and wind
.LONG TERM...(Monday through Friday)
Issued at 308 PM CST Fri Nov 9 2018
Potential impact storm at start of period, with big system still
taking shape in southern Plains but moisture plume working its way
across lower Mississippi river valley, and northern extent of
moisture is possibly working into our (mainly southern) counties at
12Z Monday. This will cause a pre-event potential for wintry pcpn
type, bc sfc temps at that time will be 30-35F. A closer inspection
of sounding data shows a pretty dry layer below 850 mb though, so
any pcpn actually reaching the ground should be very light until
later in the day, when temps will be warm enough to support all
As the long wave trof digs/sharpens upon its ejection across the
lower Mississippi river valley Monday evening, it develops a surface
Low along the Gulf coast, which lifts northeast across the Deep
South. The cold air that drags down overtop the PAH FA, will work
the profile/enable the overrunning moisture to turn from liquid to
frozen during the overnight hours. The question is, how much of that
moisture will be overrunning that far north, for appreciable pcpn.
The 12Z blended modeling/forecast builder now is producing light
amounts from a half inch to potentially an inch across portions of
our south and our east. Confidence remains low for overall
accumulating/significant snow, particularly given ground temps, but
is growing that some changeover snow will occur. Even a light event,
with Tuesday daybreak temps in the 20s, could cause some impacts
Monday night-early Tuesday morning, so it`ll be something to watch
closely as we draw nearer in time.
The 12Z Euro just in...looking more like the 12Z GFS...if that pans
out, light qpf of .1 to .2 across esp western Ky could produce a
light snowfall event for mainly Monday evening, into the overnight.
Something to keep tabs on further but will start to hit on it in the
The blend is now quicker ending the pcpn by 12Z Tuesday, so it is
almost exclusively a (Monday-)Monday night event. The blend is also
colder with the post system cold advection, keeping Tuesday Highs
in the 30s and producing some teens for Lows Tuesday night. While
a drying and moderating temperature trend is called for
Wednesday-Friday, it will remain below seasonal norms.
Issued at 509 PM CST Fri Nov 9 2018
Areas of MVFR cigs will continue this evening along with a few
light rain or snow showers mainly across southern IL into
southwest IN. Prob`s too low to include in the TAF`s. Overnight
into Saturday, mainly clear. Gusty northwest winds this evening
will diminish late tonight, and switch gradually to the north, and
then east Saturday.
IL...Winter Weather Advisory until 10 PM CST this evening for
Area Forecast Discussion
National Weather Service Sacramento CA
322 PM PST Fri Nov 9 2018
Dry with warmer than normal temperatures through next week. Critical
fire weather conditions return Saturday night through Monday
morning. Widespread smoke from the Camp Fire will continue.
Latest satellite imagery indicates smoke and haze impacting
interior NorCal as the Camp Fire continues to burn. Current
afternoon temperatures, except for the N Sac Valley, are running
several degrees cooler compared to yesterday`s given areas of
smoke. Pressure gradient has trended downward, and winds have
decreased across the region.
An upper disturbance will dig into the Great Basin Saturday night
into Sunday tightening N-S pressure gradient in the Central
Valley and SW-NE gradient over the eastern foothills and
mountains. Although these winds may not be as strong as
Wednesday night and Thursday, the combination of gusty winds and
lowering humidity will lead to critical fire weather conditions
Saturday evening into Monday morning. Thus, a Red Flag Warning is
in effect for most of interior NorCal. Winds will remain gusty
over the eastern foothills/mountains through Monday morning. Then,
lighter winds are expected Monday afternoon as surface pressure
HRRR smoke model shows smoke continuing to spread across the
entire Central Valley today, and persisting into tomorrow. Smoke
will make for a tricky forecast the next few days, especially in
areas where the smoke is thick. Poor air quality can be expected,
so make sure to check on sensitive groups.
Dry conditions will prevail across interior NorCal as high
pressure remains in control. High temperatures will continue to
run about 5 to 10 degrees above normal. Look for Valley highs in
the 70s, and 50s/60s over the mountains. Overnight lows expected
in the mid 30s to low 40s across the Valley.
.EXTENDED DISCUSSION (Tuesday THROUGH Friday)
High amplitude ridge with axis over the west coast will keep the
CWA under warm and very dry conditions Tuesday but winds should be
relatively light. Slightly warmer conditions are expected
Wednesday through Friday with daytime highs running 5 to 10
degrees above normal. Fair skies over night will allow minimums to
drop to a little below normal. No strong wind events are expected
through the extended period although models indicate a brief
period of increased ridge winds on Wednesday in the wake of a weak
system passage to the north.
Smoke from Butte County wildfire drifting Swd with areas of MVFR
ceilings and visibilities over TAF sites. Local IFR conditions may
occur briefly at times overnite. Smoke layer most likely will not
mix out due to light winds and limited mixing height on Sat.
Gusty north to east winds forecast to redevelop Sat nite into Sun
with gusts 40-50 kts possible over higher terrain and gusts 30 kts
on west side of Sac Vly. Winds decrease Sun nite and Mon.
Red Flag Warning from 10 PM Saturday to 7 AM PST Monday for
Burney Basin and Northeast Plateau in Shasta County Including
Northwest Lassen NF north of Lassen NP-Carquinez Strait and
Delta-Central Sacramento Valley in Glenn, Colusa, Yuba, Northern
Sutter, and Butte County Below 1000 Ft-Eastern Mendocino NF-
Eastern Portion of Shasta/Trinity NF-Lake County Portion of Lake-
Napa-Sonoma Unit-Northern Motherlode From 1000 to 3000 Ft.
Includes portions of Nevada-Yuba-Placer-Amador and ElDorado
Units-Northern Sacramento Valley to Southern Tehama County Line
Below 1000 Ft-Northern Sierra Foothills from 1000 to 3000 Ft.
Includes portions of Shasta-Trinity and Butte Units-Northern
Sierra Including Lassen NP and Plumas and Lassen NF/S West of
the Sierra Crest (West of Evans Peak-Grizzly Peak-Beckworth
Peak)-Northern Sierra Including the Tahoe and ElDorado NF/S West
of the Sierra Crest-Southeast Edge Shasta-Trinity NF and Western
Portions of Tehama-Glenn Unit-Southern Motherlode From 1000 to
3000 Ft. Includes portions of Calaveras-Tuolumne Unit-Southern
Sacramento Valley in Yolo-Sacramento Far Western Placer,
southern Sutter and Solano County Below 1000 Ft-Stanislaus NF
West of the Sierra Crest.