Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/02/18
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
624 PM CST Sat Dec 1 2018
.UPDATE...
Issued at 619 PM CST Sat Dec 1 2018
Made some adjustments to pops and snow totals based on current
observations and latest hi-res model guidance. Inch an hour
accumulation rates are occurring in southern Deuel county, so
still may need to upgrade them to a warning. However, radar shows
a gap in precip that will reach the area in another few hours.
Will need to see if the wave of precip behind that makes it far
enough west to really increase accumulation potential. All models
except the RAP top out the area at 5 to 6 inches. The RAP is
significantly higher at 7 to 10. Removed all counties from WSW
except Lyman. Warning amounts only possible in the bootheel and
the far southern edge of the county now. Kept Hand and Buffalo in
an advisory though advisory amounts only look possible on the
eastern or southeastern edges of Hand.
&&
.SHORT TERM...(This Evening through Sunday)
Issued at 254 PM CST Sat Dec 1 2018
A winter storm impacting the region over the next 12 to 24 hours
will produce a challenging forecast.
The biggest issue is snowfall amounts along the I90 corridor, and
over our southeastern portion of the CWA. The CWA has seen little
snowfall as of 20Z. Webcams and a few reports indicate light
accumulating snowfall in the far western portion of Stanley and
Jones County. Am very concerned the current winter storm warning
for Buffalo, Lyman, and Jones County will not verify, with
significantly less snowfall expected. The RAP models still
suggests near winter storms level snowfall in extreme southern
Lyman county, which maybe overdone when compared to the HRRR and
18Z NAM.
Snowfall amounts in our far southeastern CWA, mainly Deuel county is
also rather challenging. A narrow band of moderate to heavy snow is
currently rotating northwest across southeastern SD and southern
MN. The band should reach the CWA within the next few hours. With
an upslope wind component, wouldn`t be surprised to see enhanced
snowfall amounts. The RAP model has been very consistent with
showing 8 plus inches occurring in Deuel Co, with 6 inches
possible in parts of Grant, Codington, and Hamlin. The latest 18Z
NAM is showing something similar. Did increase snowfall amounts
for now, but will maintain the current winter weather advisory.
Drier air pushing into the Missouri River will cause the loss of
prob ice, resulting in a period of freezing drizzle. Low stratus and
fog can be expected tonight through Sunday morning as well. The dry
air should encompass the entire CWA before 18Z Sunday with no pcpn
expected Sunday afternoon.
.LONG TERM...(Sunday Night through Saturday)
Issued at 254 PM CST Sat Dec 1 2018
A large area of high pressure is over the region when the period
opens. The steering flow aloft becomes northwesterly early on, and
the most notable short-wave (clipper system) working through this
region in that pattern is progged for Wednesday/Wednesday night. For
now, most of the precipitation-producing forcing/lift with the mid-
week system is north/east of this CWA, but there is expected to be
an uptick in northwest winds immediately behind the system heading
into Wednesday night.
Low level thermal progs and NAEFS table temp anomalies support below
climo normal conditions for much of the period, with high
temperatures in the 20s to perhaps low 30s Monday through Wednesday,
but then things look to cool down Thursday through Saturday into the
teens and 20s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 525 PM CST Sat Dec 1 2018
Mainly IFR conditions are expected through tonight with some
improvement to MVFR Sunday morning. Snow will continue to rotate
into KATY this evening and overnight before tapering off early
Sunday morning. Gusty northerly winds will persist through the
period.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory until 6 AM CST Sunday for SDZ037-051.
Winter Storm Warning until 6 AM CST Sunday for SDZ048.
Winter Weather Advisory until 9 AM CST Sunday for SDZ020>023.
MN...None.
&&
$$
UPDATE...Wise
SHORT TERM...SD
LONG TERM...Dorn
AVIATION...Wise
Area Forecast Discussion
National Weather Service Albany NY
837 PM EST Sat Dec 1 2018
.SYNOPSIS...
Another wintry mixture of precipitation including snow, sleet
and freezing rain, will occur tonight into Sunday morning. This
wintry mix will gradually change over to plain rain through the
morning hours Sunday eventually tapering off to rain showers
during the afternoon.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
As of 837 PM EST...Large closed off storm system over the Great
Plains will be heading towards the Upper Midwest and western
Great Lakes for tonight into Sunday morning. Well ahead of this
system, isentropic lift ahead of an approaching warm front will
allow for a period of steady precipitation across our region,
especially for the 2nd half of the overnight hours. Precip is
finally starting to reach into the Catskills and mid-Hudson
Valley and will continue to overspread the area southwest to
northeast later through the evening hours. All areas should be
seeing precip by around midnight.
Temps have fallen this evening and most areas outside the
immediate Hudson Valley are below freezing. With dry air at low
levels, dewpoints remains in the 20s across much of the region,
which would allow for some wet bulbing effects once precip
begins, which may drop temps even further and its even possible
temps briefly drop to the freezing mark even in the Albany area
itself. Based off the 00z KALY sounding, there is a warm nose
aloft around 800 hpa to about 1 C, but lots of dry air was also
in place at that level. Wouldn`t be surprised to see precip
briefly begin as snow or snow/sleet in many areas before
transition to rain or freezing rain based of surface temps.
With surface temps so close to freezing, have decided to expand
Winter Weather Advisory to include Capital Region and northern
parts of the mid Hudson Valley, as a period of mixed precip may
make some surfaces slippery late this evening. The 23Z HRRR also
agrees with the idea of a several hour period of snow/sleet
before going over to rain/freezing rain by later tonight.
Any accumulations of snow/sleet will be light mainly a 1/2 inch
or less with closer to an inch across portions of the southern
Adirondacks and southern Green Mountains. Ice accumulations
through 6 am are expected to be around a tenth across the
portions of the southern Adirondacks, eastern Catskills,
southern Vermont into the northern Berkshires. While across the
rest of the advisory area a trace to less than a tenth of an
inch are expected. Still, this may make surface rather slick,
especially untreated roads, bridges, overpasses, sidewalks,
walkways, driveways, stairs, decks, patios, railings, etc.
Temperatures will drop this evening with loss of heating as due
to evaporative cooling with the onset of the precipitation. They
are then expected to stabilize then rise overnight, with the
only areas still below freezing by daybreak Sunday across the
Adirondacks, southern VT and perhaps the northern Berkshires.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
Winter Weather Advisory remains in effect for the southern
Adirondacks, northern Berkshires and southern Vermont through
the morning. By sunrise, freezing rain is expected to be limited
to the remaining advisory area as surface temperatures struggle
to warm with less than an tenth of an inch of additional ice
accumulations expected. By noon, the threat for the freezing
rain is expected to be over with the steady rain tapering off to
showers during the afternoon from southwest to northeast across
the local area. Temperatures are expected to rise into the
upper 30s to upper 40s Sunday afternoon.
The region will be between storm systems and with no influx of
colder air it will be mild Sunday night with lows only in mid
30s to lower 40s. Chances for showers will decrease with mainly
fair weather expected overnight except to northwest of the
Capital District and across the higher terrain of southern
Vermont into the northern Berkshires where lingering chances for
showers will persist.
Monday will be mild with temperatures expected to be about 10
degrees above normal in the upper 30s to lower 50s as we warm
in southwesterly flow ahead of an approaching cold front.
Expecting chances for showers mainly along an north of I-90.
With the passage of the cold front a colder airmass will be
ushered back in with lows Monday night expected to drop into
the upper teens to around 30 degrees. Chances for snow showers
are expected to linger due to cyclonic and upslope flow.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
The extended period begins with improved conditions as high pressure
begins ridging into the eastern third of the country from the
nation`s mid-section. A clipper system moving into the Great Lakes
region and southern Quebec through Friday will result in increasing
chances of mainly snow through the mid-week period as even high
temperatures remain down in the mid 30s or lower each day. The fast-
moving cold front associated with this system will result in a
gradual improvement late in the week, but no drastically colder
temperatures. Low temperatures will also be fairly consistent day-
to-day as lows will be mostly in the mid teens to mid 20s range. The
normal low temperatures at Albany in early December are in the mid
20s.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Flying conditions are currently VFR with increasing mid level
clouds. However, steady precip is headed towards the area and
should arrive across southern areas (KPOU, KPSF, KALB) by 03-04z
and reaching KGFL by 06z. Initially, precip will be a mix of
rain and sleet for KPOU/KALB and snow and sleet for KPSF/KGFL).
There will a changeover to FZRA at KGFL/KPSF which will last
through the rest of the overnight. Meanwhile, warming surface
temps will allow KALB/KPOU to change to plain rain by 07z.
Once precip begins, flying conditions will quickly lower down to
IFR for both vsby/cigs and this looks to be in place for the
rest of the overnight and into Sunday morning. Steady precip
will end by mid to late morning on Sunday, but some showers will
continue into the afternoon and the low-level moisture will be
trapped in place. While visibility may improve somewhat, flying
conditions look to mainly stay IFR due to low ceilings. There
could be an improvement back to MVFR by late in the day,
although this is rather uncertain.
Light winds from an east to northeast direction are expected
overnight and into Sunday morning. 2 kft winds will increase to
30-40 kts on Sunday morning from a southeast direction so have
included some LLWS for all sites. Surface winds may wind up
switching to the south to southeast on Sunday, but will remain
rather light. Winds aloft will decrease by Sunday afternoon, as
the best low-level jet shifts away from the area.
Outlook...
Sunday Night: Low Operational Impact. Slight Chance of SHRA.
Monday: Moderate Operational Impact. Chance of SHRA.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
&&
.HYDROLOGY...
Another widespread precipitation event will occur across the
area tonight into Sunday. A wintry mix including snow, sleet
and freezing rain will overspread the area this evening. This
wintry mix will gradually change over to plain rain through the
morning hours Sunday eventually tapering off to rain showers
during the afternoon. QPF amounts of 1/2 to about an inch are
expected. Flooding is not anticipated at this time. The NERFC
river forecasts has only the following river forecast points
reaching/exceeding action stage: Williamstown and Eagle Bridge
on the Hoosic River. Limited snowmelt will over the higher
terrain. It will turn colder this week with frozen precipitation
then expected.
For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory until 6 AM EST Sunday for CTZ001.
NY...Winter Weather Advisory until 6 AM EST Sunday for NYZ032-
038>041-043-047-048-051-054-058-061-063-083-084.
Winter Weather Advisory until 4 AM EST Sunday for NYZ049-050-
052-053-059-060.
Winter Weather Advisory until noon EST Sunday for NYZ033-042-
082.
MA...Winter Weather Advisory until 6 AM EST Sunday for MAZ025.
Winter Weather Advisory until noon EST Sunday for MAZ001.
VT...Winter Weather Advisory until noon EST Sunday for VTZ013>015.
&&
$$
SYNOPSIS...IAA
NEAR TERM...IAA/Frugis
SHORT TERM...IAA
LONG TERM...ELH
AVIATION...Frugis
HYDROLOGY...IAA
Area Forecast Discussion...UPDATED
National Weather Service Cheyenne WY
457 PM MST Sat Dec 1 2018
.SHORT TERM...(This evening through Sunday night)
Issued at 230 PM MST Sat Dec 1 2018
Early afternoon water vapor imagery showed an intense mid/upper
low centered over northeast KS surrounded by a large precipitation
shield encompassing much of the Central Plains into eastern portions
of the CWA. Radar, surface obs and webcams indicated the western
edge of the snow from eastern Niobrara County WY to Kimball County
NE. The steadier, periods of moderate snow were occurring over
northern portions of the NE Panhandle. Snow tapered off over the
Snowy and Sierra Madre Ranges as indicated by recent SNOTEL obs, and
the Winter Weather Advisory was cancelled. Gusty northwest winds
up to 35 mph will create areas of blowing snow and poor visibility
across the high plains through late afternoon.
Recent runs of the HRRR model prog a band of moderate snow to spread
westward from the NE Panhandle into portions of east and southeast
WY tonight. Snow accumulations of 2 to 4 inches are likely, mainly
along the I-25 corridor north of Cheyenne. Snow amounts will
taper off further east into the NE Panhandle. Following the WPC
guidance for QPF and snow accumulations, lowered totals by 1 to 2
inches. Downgraded the Winter Storm Warning to a Winter Weather
Advisory for Niobrara County. The Winter Storm Warning remains in
effect through late Sunday morning for North Sioux, Dawes and Box
Butte counties NE where four to seven inches are forecast. Two to
five inches still on target for counties included in the Winter
Weather Advisory. Periods of light snow will persist into Sunday
evening west of I-25. Low temperatures tonight will range from
the upper teens to mid 20s along and east of I-25 to the single
digits to mid teens west of I-25. Lighter winds tonight will keep
wind chills in the single digits and teens. High temperatures
Sunday will range from the low 20s to low 30s.
.LONG TERM...(Monday through Saturday)
Issued at 230 PM MST Sat Dec 1 2018
The synoptic scale pattern next week will be dominated by a broad
mid/upper trough from the northern Rockies to the eastern CONUS.
An energetic northwest flow aloft will promote colder than normal
temperatures (700mb temperatures 10 to 14C) and periodic snow
showers associated with passing weak shortwaves. The medium range
models suggest ridging aloft may put an end to the string of weekend
winter weather systems, along with a modest temperature moderation.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 447 PM MST Sat Dec 1 2018
Aviation impacts remain confined to the NE Panhandle this
afternoon and early evening with MVFR to IFR ceilings along with
light to moderate snow at KCDR and KAIA. Snow coverage has reduced
over the past several hours but a new snow band is likely to
develop north of KCYS and into the NE Panhandle again this evening
and overnight. Will need to monitor how close it comes to KCYS
for additional amendments for direct SN mention in TAF. MVFR to
LIFR conditions will persist in the NE Panhandle through mid-
morning Sunday. Lower ceilings of MVFR to IFR will also likely
spread west to KCYS and KLAR Sunday morning as well. Winds will
decrease overnight and through Sunday to 10 knots or less.
&&
.FIRE WEATHER...
Issued at 326 AM MST Sat Dec 1 2018
No fire weather concerns. Widespread snow is expected over much of
the high plains region this weekend, with an appreciable snow pack
developing for some areas. Temperatures will trend colder over the
next few days, with RH values well outside of critical thresholds.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Weather Advisory until noon MST Sunday for WYZ101-102-107-
108.
NE...Winter Storm Warning until noon MST Sunday for NEZ002-003-095.
Winter Weather Advisory until noon MST Sunday for NEZ019>021-055-
096.
&&
$$
SHORT TERM...MAJ
LONG TERM...MAJ
AVIATION...JSA
FIRE WEATHER...CLH
Area Forecast Discussion
National Weather Service Grand Rapids MI
1008 PM EST Sat Dec 1 2018
LATEST UPDATE...
Update/Marine
.SYNOPSIS...
Issued at 241 PM EST Sat Dec 1 2018
Periodic rain with a rumble of thunder tonight and a few leftover
showers on Sunday, then turning colder with some light snow for
the Monday morning commute. Cold for the rest of the week with a
clipper bringing some snow on Thursday.
&&
.UPDATE...
Issued at 1008 PM EST Sat Dec 1 2018
I made some minor changes to the going forecast, mostly the
heaviest rainfall over the NW CWA. I also delayed the temperature
rise over the central and northern CWA.
Overall there seems to be less rainfall then was forecast by the
models. I have trended down the QPF over all but the northwest CWA
where it seems the most likely area to see the greatest rainfall.
It seems to me the warm front occludes before reaching Grand
Rapids which means our temperatures will not really rise much
until the occluded front comes through here just before sunrise.
There is marginal instability south of I-96 based on MU cape (500
to 750 j/kg). There is strong upper divergence over Eastern
Wisconsin and Lake Michigan since that is where the upper jet
crosses the low level jet. It is also the right exit region of the
upper jet. It is for those reasons the heaviest rain will be over
our NW CWA tonight.
Actually there will be two bands of convection tonight, the first
is lifting through the I-96 area now but the second area,
assoicated with the front, will not reach this area until the
early morning hours of Sunday. Expect some thunderstorms (mostly
near and south of I-96) but there is a deep stable layer so I do
not expect much of an issue with severe storms.
&&
.DISCUSSION...(This evening through next Saturday)
Issued at 241 PM EST Sat Dec 1 2018
Steady rain is currently pushing through this afternoon with
scattered showers and isolated thunderstorms upstream across
northern Illinois. HRRR and other hi res models show the bulk of
that moving just west of Lower Michigan.
We will maintain continuity with the previous forecast and
include slight chance of thunder across most of the forecast area
this evening. Instability is impressive with total totals in the
upper 50s across the southern half of the forecast area. Bulk
shear values are not excessive, generally in the 30 knot range and
the storms across Illinois have not shown any organization this
afternoon.
Sfc low moves east Sunday night with colder air on the back side.
It still looks like light snow Sunday night as sfc temperatures
drop blo freezing so some icy roads could develop by the morning
commute.
Cold with light snow showers during Tue-Wed. Lake enhanced snow
showers pick up on Thursday along with light synoptic snow as
clipper moves through. This looks like a potentially widespread 1
to 3 or 2 to 4 inch snow event, followed by lake effect snow
showers into the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 644 PM EST Sat Dec 1 2018
IFR conditions will more than likely prevail for all of our TAF
sites into the early morning hours of Sunday. An isolated
thunderstorm is possible through the night but the odds of it
hitting any one taf site are to low to even put VCTS in the TAFs.
While there will be showers around from time to time it seems from
the Hi Res models it seems to me it will not be raining most of
the time. It will be windy till around 06z, then the system gets
closer to this area and winds will relaxed some. There will also
be low level wind shear till around 06z too, due to the 35 to 45
knot low level jet will be overhead till then.
Toward morning at the occluded front comes through I would expect
most of our TAF sites to become briefly VFR as the low clouds
break out and we should be between rain bands. There could be some
fog but typically when this sort of front comes through any fog
lifts and clouds break up.
Once the cold air starts coming back in by late morning or early
afternoon expect scattered rain showers and MVFR cigs.
&&
.MARINE...
Issued at 1008 PM EST Sat Dec 1 2018
I continued the Small Craft Advisory until 5 am, since it seems
it will take longer for the gusty winds in the Near Shore area so
decrease. The large waves will remain off shore due to the east to
southeast winds.
&&
.HYDROLOGY...
Issued at 1250 PM EST Sat Dec 1 2018
Rainfall amounts ranging from one-half to three-quarters of an inch
can be expected throughout the day today and into Sunday as a low
pressure system approaches from the southwest. In addition, warmer
temperatures in the 40s will help melt much of the snowpack by
Monday morning. The combination of rainfall runoff and snowmelt
throughout the weekend will lead to rises on nearly all streams and
rivers around the area. No significant flooding is expected, however
minor overflow is possible for some small to medium sized streams
around the area. These areas would include low spots near Sycamore
Creek, Looking Glass River, and the Maple River.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 5 AM EST Sunday for LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...Ostuno
DISCUSSION...Ostuno
AVIATION...WDM
HYDROLOGY...ANH
MARINE...WDM
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
913 PM EST Sat Dec 1 2018
.SYNOPSIS...
A strong low pressure system will remain to our northwest and
continue to bring widespread precipitation to the region tonight
and early tomorrow. A cold front will then move through the
forecast area later tomorrow and stall to our south and east
on Monday. Another cold front will arrive Tuesday and push our
temperatures back below normal for midweek and beyond.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 900 PM: just did a quick update to the temp trends for the
overnight to line up with obs and the latest CONSSHORT. So far,
vsbys have been holding steady, if not improving, across most of the
area. Plenty of convection across the Deep South seems to be robbing
some of the moisture transport, and resulting in diminishing
rain/shower coverage. The current PoP trends do show this decreasing
trend. Will have to keep an eye on tstms over central TN, closer to
the cold front. The last couple of HRRR runs show this activity
dying before entering the NC mountains.
As of 700 PM: Overall, the forecast looks on track. A stratiform
rain shield was seen just exiting the eastern edge of the CWFA,
while an area of showers and elevated tstms was affecting the
western half of the area. An in-situ wedge is holding tough for now,
and should preclude any severe tstms thru the evening. Temps are
actually warming a tad around the edge of the wedge, especially from
Greenwood to Charlotte. A non-diurnal temp trend will continue thru
the night, as the wedge weakens. Still concerned about dense fog
potential, but will hold off on any dense fog advisory until vsby
come down.
Isentropic lift will continue thru the overnight, and won`t totally
shut off until tomorrow. MUCAPE is progged to increase over the next
12-15 hours, sufficient enough to mention thunder chances over much
of the Piedmont. Heights aloft will fall as the upper trough
associated with the Plains low replaces the ridge over the East
Coast. Low-level flow veers to southwesterly and warm advection
occurs down to the surface. The CAD wedge will become increasingly
shallow and temps will begin to increase in a portion of our
Piedmont zones as the wedge boundary retreats northward, warming as
much as 10 degrees between sunset and sunrise. This warming trend
will continue into the day Sunday when highs are expected to be near
70 across the lower elevations. Several guidance sources, including
the majority of HREF members, depict SBCAPE creeping into our
southeastern CWFA just before dawn, lingering through peak heating
Sunday afternoon. Though the LLJ will have pushed north and east of
the area by the time this occurs, 0-1 km and 0-3 km shear/helicity
still will be strong enough not to ignore. SPC Day 1 outlook now
includes a portion of our southern SC/GA counties in the Marginal
Risk area for a 5% wind threat; the Day 2 maintains a Marginal Risk
southeast of I-85 up through the southern Charlotte metro. Skies are
expected to remain overcast over this area almost all day, and if
there are any breaks earlier that could result in an uptick that
would rapidly increase the severe threat.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
As of 200 PM EST Saturday: The short term picks up Sunday evening,
with maybe a little in the way of lingering pops in our southeast
zones, but everything moving out as the strongly occluded front
continues to push toward the coast. SW flow aloft will continue as
the sharp very positively tilted upper trough works across the Great
Lakes slowly. Will certainly see a decrease in temps behind the
front, but with SW winds continuing into Monday with a lee trough
remaining in place through the afternoon, temps will still be above
seasonal normals (kind of nice for a change) by a handful of degrees
or so. Winds will shift NW Monday night but lack of deep CAA will
keep temps from dropping to normal just yet, hovering just above.
A shortwave will push into the mountains Monday evening as the upper
trough begins to fill, but with a sharp little cutoff digging down
toward the southern Appalachians Tuesday afternoon and evening. This
is when the CAA will begin in earnest, with highs Tuesday over 10
degrees colder than those on Monday and (back to) well below
seasonal normals. Still a lot of difference in this system but
confidence is high enough to continue slight to low chance pops
across the mountains.
Tuesday night, though, confidence in sensible weather impacts
decreases. 12z GFS continues to indicate that some moisture in the
NW flow regime as the shortwave moves through will be able to break
containment, bringing some showery activity to the Piedmont
overnight - and with lows just at or slightly above freezing, could
not rule out some flurries or light snow showers. However,
operational GFS is certainly an outlier as GEFS plumes not nearly as
moist, and ECMWF has the shortwave much more open and a little
farther north. Have capped Piedmont pops at 14% and a little too
early to warrant mentioning sprinkles/flurries, but will have to
continue to reevaluate model guidance in case a quick shot of light
snow begins to look more plausible across the Piedmont Tuesday
night. Maybe some lingering pops across the mountains at daybreak,
but otherwise any moisture would be out of here before sunrise.
Colder on Wednesday behind the front, and by this time over 10
degrees below seasonal normals on another cold and blustery day
across the area.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
As of 205 PM Saturday: the extended fcst picks up at 00z on Thursday
with very broad upper trofing across the Eastern CONUS and lower
amplitude upper ridging over the Southwest CONUS. At the start of
the period, an embedded upper shortwave will be moving off the Carolina
Coast as the broader trof remains over the region. Over the next couple
of days, the trof is expected to flatten to some degree as heights
gradually rise in response. By the end of the period next Sat, the
long-range models diverge quite a bit with the GFS keeping the upper
ridge over the region, while the ECMWF brings another embedded upper
shortwave to the fcst area. At the sfc, broad high pressure will be
spreading across the region to start the period and is expected to
linger thru Friday. As we move into Day 7 on Sat, things get more
interesting. The models develop a low to our SW and move it towards
the CWFA to end the period. The system is expected to still be to
our SW at the end of the period, and it`s unclear at this point if
there will enough cold air in place to produce much frozen precip
outside of the higher terrain. For the time being, most of the snow
is confined to the Northern Mtns for Sat. Temps will remain below
climatology thru the period.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: LIFR TO IFR conditions at all sites tonight,
as an in-situ cold air damming wedge holds on. Precip is becoming
more showery in nature, and this along with continued strong
southerly flow atop the wedge will allow the wedge to begin to
weaken. Guidance generally agrees that as this happens overnight,
cigs will lower to around 200 ft and vsby may crater to 1/4 to 1/2sm
before daybreak Sunday, especially across the Piedmont sites. In
addition to this, elevated convection crossing over the wedge may
produce some occasional lightning strikes and variable
winds/vsby/cigs. Tried to base mention of TS on the latest high-res
guidance, especially the latest HRRR. A cold front will cross the
area Sunday aftn, finally scouring out the low clouds and taking
convection with it to the east. Winds are generally out of the S or
SE to start the TAF, except for NE at the Upstate sites. Then winds
will gradually veer as the wedge erodes and the cold front
approaches to SW by around 13z, increasing to around 10-12 kts. Some
low-end gusts will be possible during the daylight hours Sunday.
Outlook: Conditions are expected to continue to improve into Monday.
An upper level disturbance pushing through the region Tuesday will
support breezy NW winds with showers possible across the mountains.
Confidence Table...
02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 98% High 86% Med 68% High 91%
KGSP High 100% Med 66% Med 69% High 100%
KAVL Med 70% Med 64% Low 55% High 100%
KHKY Med 75% Med 73% Med 75% High 89%
KGMU High 94% Med 69% Low 55% High 89%
KAND High 82% Low 59% Low 47% High 91%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...JPT
NEAR TERM...ARK/Wimberley
SHORT TERM...TDP
LONG TERM...JPT
AVIATION...ARK
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1032 PM EST Sat Dec 1 2018
.UPDATE...
Issued at 1032 PM EST SAT DEC 1 2018
Still watching the two lines of showers and storms. The first one
has now shifted into far eastern Kentucky and will move across
these areas over the next few hours before exiting to the east.
The second line continues to fill in as it approaches the area.
This line will move through overnight and have refined pops to
capture this line as it moves east overnight using our local
timing tool. Still some thunder being reported at times with the
current line moving east and the line upstream. Thus, will
maintain thunder chances through the overnight hours. It does look
like all showers and storms should be to the east by dawn, leaving
behind dry conditions for Sunday.
UPDATE Issued at 700 PM EST SAT DEC 1 2018
Showers and storms from earlier have all exited the area with dry
conditions being observed over much of east Kentucky presently. A
complex of showers and storms from Richmond to Lexington will
track northeast and clip our Bluegrass counties over the next few
hours. Otherwise, we are watching a two developing lines of
showers and storms. The first one is southwest of the area and
developing to the north rather quickly. This line could develop
into east Kentucky by 9 pm. The second line is associated with the
occluded front and is presently back across western Kentucky.
These two lines will continue to blossom as we head into the
overnight hours with jet support increasing. Thus, have gone ahead
and increased rain chances to categorical for the area after 9 pm
as these lines of showers and storms push on through. Instability
remains limited to the east, so thunderstorm potential should
drop off as activity moves east overnight. However, for now, will
hang onto the thunder chances for our western zones.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 320 PM EST SAT DEC 1 2018
19z sfc analysis shows a deep cyclone over the Central Plains with
an elongated warm front stretched east into Kentucky. With this
front, scattered to numerous showers are passing through eastern
Kentucky this afternoon with a band of thunderstorms developing
over south central Kentucky well ahead of the system`s cold front.
The pressure gradient is tight through Kentucky keeping the winds
up, but still not seeing their full potential most places yet as
an inversion appears to be keeping the stronger winds aloft
confined to just our higher terrain. However, the more convective
nature of the showers and storms moving into western parts of the
area could also bring down higher winds so will keep the SPS going
for winds of 30 to 40 mph across the area through sunset. The
clouds have exhibited some breaks over the east this afternoon -
likely helping to increase the instability over the area as
temperatures have climbed into the mid 50s to lower 60s while
dewpoints are in the low to mid 50s.
The models are in good agreement aloft through the short term
portion of the forecast. They all depict a closed low over the
Central Plains opening up and working into the Ohio Valley on
Sunday and into the Great Lakes later that night. The bulk of the
energy associated with this low stays north of Kentucky until
late in the period. Given the agreement have favored the blended
solution as a starting point for the grids with a lean toward the
HRRR and NAM12 for details.
Sensible weather will feature an active late afternoon and evening
as windy conditions aloft may make it to the sfc thanks to showers
and possible thunderstorms. Meanwhile, the higher elevations near
the Virginia border continue to see some higher gusts thanks in
part to a mountain wave component to the winds running just above
the sfc. This will move off later this evening while the
convection settles down as well, limiting the stronger wind
threat. With the area in between the system`s fronts tonight we
will probably see a small ridge to valley temperature difference
into dawn. On Sunday, sunshine returns with breezy conditions
continuing on southwest winds making for another mild day with
highs in the mid 60s most places. Clouds return on Sunday night
along with winds turning more to the west generating some upslope
component enhancing the low cloud formation. Would not be
surprised if some sprinkles or drizzle develop late Sunday night,
but will leave it out for now. Temperatures into Monday morning
should be more uniform than the night before on a CAA pattern.
Used the CONSShort and ShortBlend as the starting point for all
the grids through the short term with some adjustments to
temperatures each night for terrain distinctions. As for PoPs,
generally went above the blends until the main boundary moves
through late tonight.
.LONG TERM...(Monday through Saturday)
Issued at 424 PM EST SAT DEC 1 2018
Models are in good agreement to start out the extended portion of
the forecast, with a deep southern stream longwave troughing
pattern across much of the continental U.S., and SW to NE flow
across KY. A shortwave will push southward and lower heights
across the state throughout the day Monday, becoming fairly
stationary through the day Tuesday. The GFS is much stronger with
this system, developing a upper level low, while the ECMWF is
just an open wave. Meanwhile, another trough will press southward
from Canada, merging the northern stream with the southern stream
on Tuesday. During this time the GFS has the above mentioned
shortwave maintaining strength as it slowly pushes east of the
state by Tuesday night. However, the ECMWF develops another
shortwave that tracks just north of the state during the day
Wednesday as well. Compared to yesterday, the models go back into
surprisingly good agreement by Thursday, with generally zonal
flow across the region through at least Friday. Things go awry
again as a wave develops and strengthens across the western half
of the U.S. and shifts towards the Ohio Valley. Heights begin to
lower across the state according to the ECMWF to round out the end
of the period, while the GFS keeps a dampened trough across the
region.
As for sensible weather, a secondary cold front will be moving
into the state during the day Monday, but will lose considerable
strength and dissipate as it moves across the CWA late in the day.
Kept slight to low end chance pops, mainly across the northern and
far eastern portion of the CWA as this weakening system moves
across. Much colder air near the surface will move in behind this
front, despite the WSW flow in the mid/upper levels. Highs on
Monday will be some 20 degrees lower than highs on Sunday in many
places, generally ranging from the mid 40s in the north, to around
50 in the southeast. The above mentioned discrepancy in waves
will move through Tuesday into Wednesday, resulting in the blend
having some degree of pops in place across the CWA during this
time. Since the GFS has higher pops associated with its upper
level low on Tuesday/Tuesday night, the Superblend produced 20 to
30 pops across portion of the CWA. Meanwhile, the ECMWF is much
lighter with its system, with the Superblend essentially averaging
out the pops just below mentionable criteria. Given the
uncertainty on which model is current, generally kept Superblend
pops during this time.
As the northern flow continues shift southward, colder flow will
continue to make its way into the region, with NW flow expected
aloft by Tuesday night. Highs on Tuesday will only be in the mid
30s, so precip that falls throughout the afternoon could be a mix
of rain and snow, changing over to all snow by Tuesday night. QPF
amounts are very low, especially given the lack of continuity
between the models, so any accumulations should be light,
generally a few tenths of an inch or less, and confined to the far
eastern portion of the state.
High pressure will move into the state during the day Wednesday,
with drier air advecting into the region. This will slowly
dissipate clouds throughout the day, and provide maximum
radiational cooling with light winds for the overnight.
Temperatures will fall into the low 20s across much of the region
Wednesday night, especially in the valley locations. Temperatures
will then rebound to the low 40s for Thursday afternoon as high
pressure remains in place. Another cold front will push through
the state during the day Friday. This front will also be weakening
as it reaches our region, so there is some question about the
extent of precip as it moves across the state, with the GFS
keeping us dry and the ECMWF only showing light amounts. Kept with
Superblend pops during this time since it is so far out in the
period, which only puts low in slight chance pops in during the
day on Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
ISSUED AT 700 PM EST SAT DEC 1 2018
Southeast winds will continue at 5 to 10 knots through the evening
hours, with strong flow just off the surface supporting a longer
period of LLWS. This wind shear will likely last well into the
night before the better winds shift off to the east. A front will
move through overnight with a slight wind shift to the south
expected. Showers and perhaps a few storms will accompany the
front as it passes overnight. This could bring a brief window of
MVFR conditions to the area tonight. Otherwise, mainly VFR
conditions are expected. Gusty winds will likely develop again by
Sunday afternoon.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...GREIF
LONG TERM...JMW
AVIATION...KAS
Area Forecast Discussion
National Weather Service Louisville KY
928 PM EST Sat Dec 1 2018
.Forecast Update...
Issued at 928 PM EST Sat Dec 1 2018
The forecast is in good shape and no significant updates are needed.
A broken line of elevated showers continues to cross central
Kentucky at this hour, and may mix down some 30-40mph wind gusts.
Overall, though, an inversion around 3kft has been keeping the
strongest winds aloft.
Shower activity should end across central Kentucky by 2am EST.
&&
.Short Term...(This evening through Sunday)
Issued at 305 PM EST Sat Dec 1 2018
As a deep surface and upper low spin over N/NE Kansas this
afternoon, the warm conveyer belt well ahead of this system
continues to cause scattered to numerous showers and a few embedded
thunderstorms over the OH and TN Valleys. For example, a small line
of thunderstorms with some CG lightning has been progressing NE over
parts of south-central KY the last hour, but is now slowly
weakening. Winds associated with this line earlier were still
slightly elevated as surface wind speeds were not much different
than ambient values across central KY this afternoon.
As expected, surface temps this afternoon have been roughly steady
in the mid 50s to around 60, although thinning clouds in SW KY has
allowed temps there to rise into the mid 60s at this time. Across
our area, expect to see temps rise slowly late this afternoon and
top out actually during the evening hours as southerly flow
continues across the area just off the surface.
A couple AMDAR aircraft soundings continue to show a low-level
inversion around SDF which has prevented stronger surface wind
gusts. However, the inversion is a little weaker over western KY and
SW IN allowing surface winds as shown by ASOS and KY Mesonet sites
to gust from 20-25 mph. Winds over central KY and southern IN should
become a little more gusty later this afternoon and evening as well.
As for precip, high-res/convection-allowing models are not
consistent in their new term solutions. The latest HRRR continues to
show another line or two of convection forming on the western edge
of the moist axis over the lower OH Valley and progressing NE over
our area late this afternoon and evening. The WRF runs and NAM3 are
not as emphatic but still show potential for isolated to scattered
convective cells. Instability appears that it will remain largely
just elevated meaning locally heavy rain and perhaps small hail in
any stronger cores.
All precip will push NE this evening, ending last over east-central
KY late this evening. Behind it, expect clearing skies overnight as
the dry slot works farther NE into our area. Lows by Sunday morning
should be in the upper 40s over southern IN and around 50/lower 50s
in central KY.
On Sunday, expect plenty of sunshine as we remain in a low and mid-
level dry slot. The main concern Sunday will be surface winds. With
30-50 kt winds forecast from 925-850 mb and steep low-level lapse
rates by late morning and afternoon, S to SW surface winds could
gust over 30 mph at times. No wind advisory at this time, but this
may have to be considered in later forecasts. Given the sun and
gusty winds, afternoon highs Sunday should reach well up in the mid
and upper 60s in central KY, possibly a bit cooler over southern IN.
.Long Term...(Sunday night through Saturday)
Issued at 255 PM EST Sat Dec 1 2018
The large system affecting the short term finally will bring its
associated cold front to the Ohio Valley Monday. It looks like it
still will not be in a hurry to clear the area, and a few models
spit out some precipitation either along or just behind the front.
Given the cold air in place, this could end up as mix of rain or
snow or drizzle, depending on the depth of the moisture into the
colder air aloft. This "marginal" situation could extend through
Tuesday, as waves aloft move across the region from the northwest.
Midweek "looks" dry for now, but any quick-moving impulses in the
weak trough pattern aloft could provied a brief very light precip
event. Blended forecast for now keeps the forecast dry, and will
lean that way for now.
Speaking of quick-hitting, another moisture-starved front looks to
move through here some time Thursday. Only have a slight chance for
showers in the afternoon. That front may linger close enough to the
region to meander back north and affect us for the upcoming weekend,
as a southern stream system moves across the Deep South. As is usual
this far out, there still are plenty of question marks with this
system. Blended forecast will has snow Friday night transitioning to
rain or mix during the day.
Temperatures generally stay below normal for this period.
&&
.Aviation...(00Z TAF Issuance)
Updated at 618 PM EST Sat Dec 1 2018
Low ceilings and scattered thunderstorms will continue to stream
rapidly northeastward ahead of a dry slot that is in turn ahead of a
strong upper low near MCI this evening. Overnight the low will head
northeast into Iowa and will pull the dry slot into southern Indiana
and central Kentucky, shutting off the storms and bringing in clear
skies. On Sunday the low will fill as it tears northeast to Lake
Huron, with low-end MVFR clouds sweeping into the Ohio Valley on
cold air advection behind the departing storm system.
Winds will be brisk from the south tonight, occasionally gusting
over 20kt especially this evening. AMDAR soundings have been showing
a sharp low level inversion around 2500-3000 feet at BNA and 4000
feet at SDF which has been keeping the strongest winds off the
surface.
Tomorrow there should be good mixing with sunshine, especially at
BWG and LEX where more sunshine is expected. Winds coming in from
the southwest will gust to 30kt.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...13
Short Term...TWF
Long Term....RJS
Aviation...13
Area Forecast Discussion
National Weather Service Omaha/Valley NE
916 PM CST Sat Dec 1 2018
.UPDATE...
Issued at 915 PM CST Sat Dec 1 2018
Made a minor update to increase snow amounts in parts of southwest
Iowa where recent RAP and HRRR model runs have shown potential for
amounts upwards of 6 inches.
Otherwise, nearly stacked low pressure system continued to lift
slowly northeast. Main center in the mid levels appeared to be
over northwest Missouri, but there were other embedded
circulations pivoting counter clockwise around the low. Heavies
snow seems to have been across the northern parts of northeast
Nebraska based on what reports we have received so far.
No other changes except minor tweaks to wind and temperatures.
&&
.SHORT TERM...(Today through Monday)
Issued at 333 AM CST Sat Dec 1 2018
This storm system continues to impress with its complexity, and
have continued to attempt to adapt the forecast to match up with
the latest trends in observational and model data. In terms of
what has happened so far, snow amounts range wildly even across
areas that have seen persistent snow fall. Melting has played a
huge role that seems to be magnified by the rain that fell prior
to snow, and also by the relative warmth of the snowflakes that
are falling through a fairly deep warm layer above the surface.
The end result has been that snowfall predictions seem to have
been pretty accurate but some of the snow accumulation amounts on
the ground have been on the low end so far, owing to that melting.
That said, several reports in the 5-6 inch range have come in to
the office, and expect a slow but steady accumulation of
additional light to moderate snow in these areas all the way
through Sunday.
Would like to focus on 3 key areas for the forecast through the
rest of Sunday. The first is in far northeast Nebraska where 2-7
inches of snow has fallen by now. There is a strong signal for
persistent light to moderate snow over the next 12 hours or so and
even into the day on Sunday. Deformation and mid level
frontogenesis will remain focused in this area for a prolonged
period with very little movement of the overall storm system. Do
expect a banded area within this region to total out in the 9-12
inch range by the time its all winding down.
The second area of focus is what is expected to be a relatively
persistent band of moderate snow extending from around David City
and Columbus up through Stanton, Wayne, and West Point. While it
may fluctuate west or east of this axis with time, it should
remain in the general vicinity and lead to several additional
inches of snowfall through tonight before it weakens and
dissipates.
The third area, and perhaps the biggest change in the forecast is
over southeast Nebraska up toward Omaha and into southwest Iowa.
It has become increasingly apparent over recent model and
observational data that the zone immediately northwest and west of
the low will be a focus for moderate precipitation through around
sunrise on Sunday. That will lead to a prolonged period of what
should be a majority of snow that pivots and focuses in the
general Nebraska City and Shenandoah areas. This band will be
between 50-100 miles wide for much of its lifetime and at least
initially surface temperatures will be warmer than freezing. The
difference between this snow and the snow of this morning is that
it will fall at night which favors slightly better accumulation
but will still experience some melting. At this time have gone
with a 2-6 inch prediction and also expanded the advisory across
the remainder of the CWA, but will need to closely monitor trends
as it is not out of the question that some of these areas could
end up exceeding 6 inches by Sunday morning in what is a very
delicate forecast of snowfall vs. snowmelt.
Sunday into Sunday evening will feature periods of light snow
moving across the entire forecast area and gradually coming to an
end from northwest to southeast by late in the day. Winds will
continue to gust in the 20-30 mph range through the day with
cooler temperatures steadily building into the region.
.LONG TERM...(Tuesday night through Saturday)
Issued at 121 PM CST Sat Dec 1 2018
Snowy conditions may linger through Monday night as this low
pressure system drifts off toward the Great Lakes. The bulk of the
accumulating snow will end Sunday however some light snow may hang
around Sunday night in southeast Nebraska and southwest Iowa.
By Monday high pressure begins to build back into the area
bringing mainly drier weather and colder temperatures through the
week. High temperatures are expected to be mainly in the 20s with
lows in the single digits and teens through the longer term
period.
Wednesday, a few locations in far southeast Nebraska and southwest
Iowa may break the freezing mark with highs reaching the mid 30s,
however this "warmth" will be short lived mainly 20s returning
again by Thursday.
A shortwave system on Thursday may bring some
light snow to southern parts of Nebraska and Iowa however this
will be fast moving which should limit any significant
accumulations.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 520 PM CST Sat Dec 1 2018
Expect snow to continue at KOFK with IFR conditions most of the
period. Winds may also cause blowing snow there.
For KOMA and KLNK, also expect ceilings mainly at or below 1000
feet with mostly visibilities below 3 miles. Some blowing snow is
possible, mainly at KLNK.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory until 6 PM CST Sunday for NEZ034-044-045-
050>053-065>068-078-088>093.
Winter Storm Warning until 6 PM CST Sunday for NEZ011-012-
015>018-030>033-042-043.
IA...Winter Weather Advisory until 6 PM CST Sunday for IAZ043-055-056-
069-079-080-090-091.
&&
$$
UPDATE...Miller
SHORT TERM...BLB
LONG TERM...HB
AVIATION...Miller
Area Forecast Discussion
National Weather Service Nashville TN
550 PM CST Sat Dec 1 2018
.UPDATE...
FOR 00Z AVIATION DISCUSSION.
&&
.DISCUSSION...
Showers and a few thunderstorms across the area are weakening
currently, and are having a tough time staying together this
afternoon. 18Z sounding from OHX showing a decent low level
inversion, with some elevated CAPE from 850 mb. Also showing some
drier air aloft, and with strong 80 knot 0-6km shear, likely
having a hard time staying together before that dry air entrains
and mixes to dissipate the showers. Short term models and CAMs are
hinting at a weak front sneaking through the mid state from 00Z-
06Z this evening, and kicking off some convection out ahead. The
HRRR has been the most bullish with this solution, and following
suit is the NAMNest and even the hi-res WRF models. Adjusted pops
up slightly for this evening to account for the precip, but
instability falls off rapidly after 00Z so not sure if there will
be much in the way of stronger cells east of I-65. Will continue
to monitor for any potential for damaging wind gusts or even some
small hail, especially west of I-65 as developing convection
utilizes some of the remaining instability.
Winds will continue to decrease tonight and through the overnight
hours, but pick up again during the day Sunday ahead of the
approaching cold front. There wont be a dramatic wind shift during
the day tomorrow since winds will remain southwesterly and keep
temps warm, but slowly will become westerly Sunday night then
northwesterly by Monday. Cold front is more evident with 850mb
temps, and cold air will begin working its way southward and
eventually have the entire mid state below 0C at 850mb by mid
afternoon. Temperatures will be below average through the week as
any substantial warming will be absent thanks to the lack of
strong southerly flow.
Conditions will remain dry Monday, but a slow moving upper trough
will continue to keep cold air aloft, and may bring some precip
chances during the day Tuesday. Moisture is struggling to show up
for this event despite a few hints of QPF between model
solutions. Kept most of the mid state dry except for the northern
Plateau where some orographic help may be able to squeeze out some
moisture for precip. Temps will be cold enough for some snow to
mix in, but likely just some light rain chances. Tuesday night may
see some flurries over the northern Plateau before dry conditions
return for Wednesday and Thursday with upper ridging/northwest
flow aloft.
On Friday, some shortwave trough activity may kick off some
showers during the day, but better precip chances are in store for
the weekend as a stronger upper shortwave moves through the area.
Models are not lining up yet, of course, but do hint at similar
low level solutions and QPF timing. So have chance pops in for
Saturday and Sunday. Friday night and Saturday night, temperatures
are cold enough for some snow to mix in, but further drops in
temperature with next runs will yield more snow. Current lows are
in the mid 30s, so still too close to call just yet on snow
potential next weekend. Leaned towards the warmer solutions and
have mainly rain in during daytime hours, and a rain snow mix
during the overnight.
&&
.AVIATION...
00Z TAF DISCUSSION.
Scattered showers could impact the terminals during the first 6
hours of the taf period and then vfr conditions will quickly
return. A line of showers currently just west of CKV will be the
last threat to the terminals. That line will move east of CSV by
08z. Winds will calm to 5-10 kts behind the line. Winds will
increase to 10-15 kts with some gusts to 20 kts out of the
southwest after 15z.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION......Barnwell
AVIATION........Reagan
Area Forecast Discussion
National Weather Service New York NY
800 PM EST Sat Dec 1 2018
.SYNOPSIS...
High pressure will continue to give way to a storm system over
the Mid Mississippi Valley. The associated low will track up
into the Great Lakes by Sunday night, sending a warm front
through the region on Sunday, followed by a cold front late
Monday and Monday night as the low continues into the Canadian
Maritimes. High pressure then builds into the region through
midweek. An upper level disturbance could produce light wintry
weather Thursday night into Friday.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Update this eve mainly reflects more defined pops based on
radar and trends in HRRR since it is capturing reality well.
Initial band of overrunning WAA rain ahead of a warm front
moves across the Tri State Area through 2z, with a brief break
before the rain picks up again after midnight as a strengthening
low- level jet moves up the coast and enhances thermal forcing.
E to SE winds will also pick up through the night as the
gradient between the departing high and approaching low tightens
across the region. Gusts up to 20 mph will possible at the
coast by daybreak. Areas of fog will also develop late as low-
level moistures increases and the airmass saturates beneath a
strengthening low-level inversion.
Lows will be achieved early this evening, in the mid 30s to
lower 40s, then slowly rise overnight.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
A moderate rain will mainly fall during the morning hours Sunday
along and ahead of a warm front. An isolated thunderstorm also
can not be ruled out as instability develops aloft. As the low-
level jet translates east by afternoon and the warm front lifts
north of the region the rain will transition over to drizzle and
may even end all together by early evening. Areas of fog and
low clouds could persist into the night.
Sunday and Sunday night will be considerably warmer in the warm
sector due to a deep-layered SW flow ahead on approaching cold
front. Highs Sunday will get into the 50s for most locations and
then don`t fall off much overnight. Readings will generally be
8 to 15 degrees above normal.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Long term period looks fairly uneventful for a change with NWP in
good agreement until mid-late next week.
Potent shortwave and associated sfc low pass north of the area
on Mon with more sheared mid/upper level energy ahead of the
trough axis passing through southern New England Mon night. It
will continue to be gusty but warm (mid to upper 50s) on Mon as
the departing storm strengthens and high pres builds from the
Plains. CAA behind the cold front could also keep gusts into the
overnight hours. Moisture appears to be limited, so other than
an increase in cloud cover, the passage of a cold front and the
upper trough axis Mon night is expected to be dry. There is some
weak lift however, so if any light pcpn were to reach the
ground, it could be sprinkles or flurries depending on timing.
Ridging then builds at the sfc and aloft through the middle of
the week. Winds diminish on Tue, especially in the aftn, as the
high builds and the gradient relaxes. Dry with below normal
temps will be the rule through Thu. Will need to keep an eye on
a vigorous shortwave approaching from the Midwest on Wed.
Differences in model solutions begin to unfold with this which
could influence the remainder of the forecast period. All 12z
guidance has this shortwave passing to our south with
cyclogenesis occurring off the Mid Atlantic coast. GFS is the
fastest and EC is the strongest/earliest with cyclogenesis.
However, it is close enough to the local area that it continues
to bear watching despite the trend to the south.
A weakening shortwave diving out of western Canada then
approaches for Thu night/Fri morning. The combination of WAA and
the exit region of a 90+ kt jet streak could be enough to
produce light QPF across the area. Thermal profiles indicate the
boundary layer should still be cold enough for snow showers
despite the WAA.
Dry weather then returns through Sat as high pres builds from
the west. Temps will remain below normal.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
A warm front approaching from the southwest should lift to the
north by early Sunday afternoon.
Band of light rain moving across the NYC metros and lower Hudson
Valley attm accompanied by mainly VFR conds. Cigs after passage
of this band have dropped to MVFR at the PHL metros and to IFR
north/west, so expect the metros to drop to MVFR as well, then
to IFR late tonight into early Sunday morning, and remain that
way for most of Sunday as additional rain moves in. It is
possible that conds could improve to MVFR sooner than forecast
as winds shift from E to S with the warm fropa.
There is slight chance of a tstm thunderstorm Sunday morning.
Chances too low to reflect in TAF.
LLWS possible late tonight into Sunday afternoon at all but
KSWF.
.OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY...
.Sunday night...Slight chance of showers early with MVFR or
lower possible, otherwise VFR.
.Monday...VFR. WSW-W winds G15-20KT.
.Monday night-Tuesday...VFR. NW winds G15-20KT.
.Tuesday night-Wednesday...VFR. NE-N winds G15-20KT.
.Wednesday night...VFR.
.Thursday...VFR. W winds G15-20KT.
&&
.MARINE...
The combination of departing high pressure to the north and
east and an approaching warm front from the southwest will
allow for a strengthening easterly flow overnight, which veers
around to the southwest behind a warm frontal passage Sunday.
SCA conditions are likely across the ocean waters late tonight
through Sunday night, with a shorter window for gusts across
the eastern Sound and bays.
SCA will likely be needed on the ocean waters, possibly on
eastern LI Sound and adjacent bays, through Mon night, possibly
Tue morning as a strong W flow becomes NW. As low pres departs
and high pres builds from the west winds will diminish with
sub-advsy conds then expected until possibly Fri.
&&
.HYDROLOGY...
Up to an inch of rainfall is possible tonight through Sunday.
Any hydrologic impacts should be minor.
No hydrologic concerns are then expected through the end of next
week.
&&
.TIDES/COASTAL FLOODING...
A coastal flood statement has been issued for portions of the
coastline adjacent to western Long Island Sound for the Sunday
morning high tide cycle. Easterly winds strengthen ahead of an
approaching warm front, producing a surge of 1 1/2 to 2 ft.
This will bring water levels close to minor coastal flood
benchmarks in a few of the more vulnerable spots. Elsewhere,
particularly the vulnerable south shore bay locations of
western Long Island, it seems less likely due to the timing of
the wind forcing.
&&
.EQUIPMENT...
NYC Central Park winds are out of service until further notice.
Loss of data is due to a severed cable. Parts are on order.
NYC NOAA Weather Radio Station KWO35 (162.55 MHz) will remain off
the air for an extended period of time.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from midnight tonight to noon EST Sunday
for ANZ330-340-345.
Small Craft Advisory from midnight tonight to 6 AM EST Monday
for ANZ350-353-355.
&&
$$
SYNOPSIS...24/DW
NEAR TERM...DW
SHORT TERM...DW
LONG TERM...24
AVIATION...Goodman
MARINE...24/DW
HYDROLOGY...24/DW
TIDES/COASTAL FLOODING...
EQUIPMENT...
Area Forecast Discussion
National Weather Service Blacksburg VA
853 PM EST Sat Dec 1 2018
.SYNOPSIS...
A wedge of high pressure will erode this evening, with steadily
warming temperatures overnight tonight. A cold front will move
across the area early Sunday. While temperatures will be above
normal tonight into Sunday, high pressure across the center of the
country will usher in a colder air mass for early next week.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 850 PM EST Saturday...
The 00Z RNK sounding shows an impressive low level inversion
keeping a cool and moist wedge at the surface. Visibilities
have improved at many locations, but will continue to keep the
dense fog advisory in place as mesoscale models and SREF indicate
visibilities drop, especially east of the Blue Ridge.
Considering the strength of the inversion, slowed the rate of
warmth overnight, as low level wedge may remain in place longer
than earlier forecast as shown by many of the mesoscale models
and the latest NAM nest. Also brought down temps a couple of
degrees at LYH tomorrow with slower erosion of the wedge.
Convective line of storms across eastern TN/KY will have a very
difficult time surviving as it leaves the small ribbon of
instability as shown on the SPC mesocale analysis page. However,
this will likely bring another round of light to moderate rain
to the western portion of the forecast area around or after 06z
as shown by the ARW-NMM which was one of the few mesoscale
models that picked up on this convection.
As of 520 PM EST Saturday...
The combination of moist ground, rain and drizzle in the area,
and a wedge of cool air undercutting the upper-level moisture
has contributed to the development of widespread dense fog and
drizzle. It pretty much appears like it is going to be one of
those nights where much of the CWA is completely socked in with
fog, drizzle, and low clouds. Visibilities are near zero in many
locations above 2000 feet elevation near the Blue Ridge and also
across much of the Piedmont widespread 1/4 to 1/2SM. HRRR
suggests little improvement overnight. Perhaps rain areas may
move in later, but right now it appears that they will split for
the next several hours at least and go north or south of our
area. Therefore, have issued a Dense Fog Advisory for all but
some far western VA/WV counties until 13Z Sunday. Will continue
to monitor to see if an expansion in area or time is needed.
As of 251 PM EST Saturday...
Stubborn in-situ wedge has surged into northern Carolinas and has
led to overall cool temperatures, extensive low clouds with fog at
times across essentially the Piedmont, Blue Ridge, foothills into
the New and southern Shenandoah Valleys. Fog should begin to become
less prevalent as winds increase and become southerly (as opposed to
light east). Had issued a SPS for continued fog for the
aforementioned areas until 330 PM.
Otherwise, a vertically-stacked low centered near Kansas City trails
a long tail of warm-advection rain from the Great Lakes,
Appalachians into the northern Gulf Coast states. Southern end of
this precip shield is affected our southern and eastern counties,
and will continue to do so through the first part of the evening.
Best chances/highest PoP for steadier rains is from the NC Piedmont
through areas along/east of the Virginia Blue Ridge. Have shown a
local minimum in PoPs through midnight from the New River Valley/NW
North Carolina Mtns westward into southeastern West Virginia through
midnight, where dry slot aloft is currently progressing across the
Ohio/Tennessee Valleys. These trends are all generally reflected by
most of the coarser-res NAM/GFS and the finer resolution NAM-3km and
HRRR guidance. Will be areas of mist and fog as well, though
visibilities should be higher than current and coverage will tend to
be restricted to east of the Blue Ridge into the
foothills/Piedmont/Southside. After 06z/2 AM, while the eastern two-
thirds of the CWA clear out with lowered PoPs, things get
potentially more interesting in western areas, as a number of higher-
resolution guidance break out a scattered band of convectively
enhanced showers along the cold front/wind shift. This appears to be
models keying on the convection occurring near Nashville/Middle TN.
Showalter indices drop to around -1 to -2 on the NAM, which suggests
elevated instability above stable surface-based conditions. Have
included a slight chance of thunder in these western areas between
the overnight and pre-dawn hours, and while wind shear is pretty
stout low-levels are still much too stable to allow for even gusty
convective winds to be transported to the ground. Regarding
temperatures, a largely non-diurnal approach was taken and given the
way the day has unfolded, it`s quite likely that calendar-day highs
occur overnight tonight. As the wedge erodes, 850 mb temperatures
rise to +11 to +13C overnight along with increasing dewpoints into
the upper 40s to the 50s. Look for early lows in the 40s to low 50s,
with most areas reaching the low-mid 50s by early Sunday morning.
QPF amounts run from about a quarter to nearly a half-inch.
Cold front aloft will continue to be progressing across our eastern
two-thirds of the forecast area. This will clear most areas out with
lowering PoPs. Greater potential for warming and drying pre-frontal
across Southside into the NC foothills/Piedmont leads to a potential
threat of thunder here. The milder GFS show surface based CAPEs
closer to 800 J/kg in this axis, while the still cooler and more
stable NAM shows this instability above stable inversion. Think
there is a non-zero threat of stronger cells in a high-shear/very
low CAPE environment from Yadkinville to Mount Airy NC northeastward
into Southside Virginia tomorrow late morning/early afternoon,
particularly if a stability profile more like the GFS
materializes. A NAM depiction would lend to less likelihood of
stronger convective gusts given the stabler profile. Shear
through low levels and deep layer are quite strong, but is
mostly straight-line from a hodograph perspective. SPC keeps
probabilities of severe weather farther south and east in the
Day-2 outlook, with general thunder this far north. There`s
still a good deal of uncertainty on the potential, as alluded
to, but think it is prudent to raise awareness of stronger
thunderstorms from Yadkin County north/east into Southside
highlighted in the HWO. Highs will run from the 60s to the low
70s, with potential for low- mid 70s in Southside/NC Piedmont if
greater warming can materialize.
Forecast confidence is overall moderate to high for the tonight
period, but is lower on the potential for thunderstorms tonight and
early Sunday as well as on temperatures Sunday.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 254 PM EST Saturday...
Cold frontal passage will occur Sunday night into Monday morning
bringing low level upslope clouds, mainly in the west. After being
spoiled with a warm Sunday, temperatures will begin to trend
somewhat cooler on Monday with highs in the 50s for the mountains,
and low to mid 60s east. Temps will drop to below normal values for
Tuesday with high temps for most in the mountains struggling to get
to 40, and mid to high 40s for the foothills and piedmont. Winds
will be westerly which will trend to the northwest Monday evening
and remain for the duration of the period. Increased upslope flow
will cause enough moisture to gather to bring isolated showers to
the mountains with snow possible in the higher elevations. Coverage
Monday night will be restricted to the farthest western areas
however will expand through Tuesday into Tuesday night. By Tuesday
night, temps will drop far enough that any precipitation that falls
will likely be as snow or at the very least a wintery mix. As of
now, precip amounts look to be rather low, therefore any significant
accumulating snowfall appears unlikely for all areas, with the
exceptions possibly being the typical upslope areas in the NC high
country and higher elevations WV.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 254 PM EST Saturday...
Forecast models continue to advertise a broad trough over the
eastern US through the period which will continue to support below
normal high temperatures through the period. Have opted for a model
blend as there are several different outcomes as to just how cold it
will actually become.
Upslope snow showers will begin to taper off Wednesday but will
continue to be possible, mainly in the far western areas. A weak
disturbance passing through the area on Friday will also promote
some additional showers Friday into Friday night.
Late in the work week, models are showing a fairly decent low
pressure system developing well to the southeast which could entrain
enough moisture to bring some impact to the Mid-Atlantic as early as
Saturday. Confidence is low at this point on when or what impact
this system will have on the forecast area at this point, but will
be paying close attention in the coming days.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
As of 645 PM EST Saturday...
Poor to very poor flight conditions expected through around 13Z
Sunday morning. Classic wedge set up reinforced with light rain
and drizzle. Do not expect any erosion of the wedge before
daybreak, likely holding in until 13-14Z. However, as the wedge
breaks, gusty southwest winds will evolve quickly in its wake,
clearing out the low clouds, fog, and drizzle and bringing VFR
conditions with unseasonably warm temperatures by afternoon.
Periods of light rain will spread across the region overnight
into the morning, but no significant rainfall is expected. The
bulk of the support for heavier rain showers will remain to our
south where the southern stream is focused. Thus, either -RA or
-DZ BR/FG in place at all TAF sites overnight/early morning
Early Sunday morning, a cold front will begin to approach from
the west. May be convective elements/chance of thunder from
Blacksburg west between 08-12z but confidence too low to
incorporate in the TAF; will mention SHRA in areas that have an
outside thunder potential. This front will progress across the
Blue Ridge and points east into the Piedmont toward the latter
part of the 18z TAF period. Very limited threat of thunder
further east, but will not include in the TAFs at this time.
Main threat for thunder will be well east and south of our CWA.
Winds...east to southeast (northeast at Lynchburg) 4-8 kts will
tend to veer to southeast/south this evening. Will see an
increased potential for low-level wind shear as south/southeast
jet of 40-45 kts affects terminals from Roanoke west. Winds will
shift to the southwest with speeds 5-10kts around mid-morning
Sunday.
/Confidence Levels in Forecast Parameters/
Ceilings - Moderate to High,
Visibilities - Moderate to High,
Winds - Moderate to High.
Extended Aviation Discussion...
Cold northwest flow will gradually return through the week and
the weather pattern will resemble winter again. Isolated MVFR
showers are possible on Monday but most areas dry and VRF with
better chance for snow showers in the mountains by late Monday
night into Tuesday as push of colder air behind front moves in
and winds shift from west to northwest but not especially
strong. MVFR snow showers and snow flurries may continue in the
northwest mountains on Wednesday.
&&
.EQUIPMENT...
As of 400 PM EST Saturday...
The KDAN ASOS has been repaired.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Dense Fog Advisory until 8 AM EST Sunday for VAZ011-013>020-
022>024-032>035-043>047-058-059.
NC...Dense Fog Advisory until 8 AM EST Sunday for NCZ001>006-
018>020.
WV...None.
&&
$$
SYNOPSIS...AL
NEAR TERM...AL/PH/RAB
SHORT TERM...JR
LONG TERM...JR
AVIATION...AL/RAB/WP
EQUIPMENT...AL/WP