Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/01/20
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1045 PM EST Mon Nov 30 2020
.SYNOPSIS...
Scattered areas of rain this evening capable of brief heavy
downpours will weaken overnight to isolated showers.
Temperatures remain mild tonight and Tuesday with some lingering
rain showers during the day. Cooler conditions return for mid
week, along with scattered rain and snow showers.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 10pm EST, SPC mesoanalysis shows the 1 inch PWAT contour
is still over eastern NY and western New England which explains
why these final scattered areas of rain that have produced heavy
downpours. Luckily, the downpours have been fairly brief but
since most areas outside of the southern Adirondacks and
western Mohawk Valley have seen a soaking rainfall today
(amounts between 1.25 - 2.25", up to 3.50" in the eastern
Catskills), we continue to closely monitor river levels. The
Esopus Creek and Schoharie Creek are the main river basins we
are monitoring but after coordination with the NERFC, current
thinking is for the forecast points along these rivers to fall
just shy of flood stage.
The HRRR has done fairly well in timing the end of these last
few areas of rain and it shows a drying trend ensuing through 06
UTC. After 06 UTC, just a few isolated showers are possible so
we trended current high chance POPs quickly down to slight
chance. We lingered slight chance POPs through morning as our
parent low becomes vertically stacked and remains overhead.
The system`s cold front is not expected to pass through the
region until tomorrow morning so areas from the Capital
District south and east will remain in the warm sector overnight
leading to mild and even muggy conditions. Temperatures should
stay in the 50s to even low 60s in this region with dew points
in the in the mid to upper 50s. The combination of muggy
conditions and light wind has led to some fog formation tonight.
This should linger until 06 - 09 UTC when winds should finally
increase enough to scour out the fog. If fog become dense and
widespread enough before that time, we may need to issue a
Special Weather Statement to alert users to reduced
visibilities.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
Additional showers are possible on Tuesday as the main upper
low moves through New York. Best chances look to be across
northern areas, closest to the low center. Highs on Tuesday will
be realized early in the day as the leading edge of cold air
moves into the region ahead of the front. Many could see the
temps either staying steady or dropping throughout the day.
Lows Tuesday night will drop below freezing everywhere.
The cold front moves through late Tuesday into Wednesday.
Rain/snow showers will be possible with the frontal passage
during this time with the southern Adirondacks possible seeing
advisory level snowfall. Highs on Wednesday will be seasonable,
in the low 30s to low 40s.
Dry weather returns Wednesday night through the day Thursday.
This is a brief reprieve in between northern stream systems.
Highs on Thursday warm a few degrees into the mid 30s to mid
40s.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
High degree of uncertainty/low confidence forecast for much of the
long term, especially regarding any potential phase interaction
between northern and southern stream energy next weekend into early
next week.
Before any possible interaction, departing upper level low from
midweek continues to drift farther north into east central Canada,
with decreasing influence on our region Thursday night. Still some
clouds/snow showers possible across portions of the SW Adirondacks,
otherwise lingering clouds likely across at least central and
northern portions of the region. Near seasonable temperatures, with
lows Thursday night mainly in the mid 20s to lower 30s, although may
be slightly warmer where clouds persist.
Then, northern stream energy approaches from the Great Lakes region
for Friday-Monday, while southern stream energy ejects
east/northeast toward the mid Atlantic/southeast coast. Although
12Z/30 ECMWF and FV3 suggest little, if any interaction between
these two disturbances until well offshore, several 12Z/30 GEFs
members, and the 12Z/30 GEM still suggest greater chances for
interaction and potential storminess next weekend. Will therefore
keep slight chance to low chance PoPs throughout this period due to
the uncertainty, with the possibility of a more significant storm
system still within reasonable probabilities. This portion of the
forecast will be greatly subject to change until better sampling of
individual disturbances as this week progresses.
With the threats for precipitation, will keep showery wording for
now, with a slight edge on the assumption that precipitation will be
forced mainly by the approach of northern stream disturbance and
some added Lake enhancement. P-type mainly snow for higher
elevations, with snow during the night for valley areas, and
rain/snow mix for valleys during the daytime hours.
Temperatures should cool closer to seasonable levels through the
period, with daytime highs mainly in the mid 30s to lower 40s,
although perhaps colder by next Monday (20s for higher elevations,
30s for most valley areas). Overnight lows mainly in the mid 20s to
lower 30s.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
VFR ceilings currently in place at GFL and ALB with MVFR
ceilings at PSF and POU. Visibilities have improved to VFR at
all sites and are expected remain as such overnight. Ceilings at
GFL and ALB expected to drop back to MVFR by 03 UTC with all TAF
sites remaining MVFR overnight. There is potential for some
brief period of IFR ceilings 09 - 12 UTC mainly at GFL but we
did not have enough confidence to include at this point.
Ceilings should become scattered to broken tomorrow with even
potential breaks of sun. However, with intermittent showers
still possible, we maintained MVFR ceilings until after 18 UTC
when there is more confidence that VFR ceilings finally return.
South to southeasterly winds will remain sustained 5 - 10kts
overnight but strengthen by 15 - 18 UTC to be sustained 8 -
15kts as the occluded boundary progresses through the area. LLWS
tonight should only last through 06 - 09 UTC when the low-level
responsible for 2 kft winds 35 - 45kts should exit out of our
area.
Outlook...
Tuesday Night: Moderate Operational Impact. Chance of SHRA.
Wednesday: Low Operational Impact. Slight Chance of SHRA.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: Low Operational Impact. Slight Chance of SHRA.
Friday Night: Low Operational Impact. Slight Chance of SHRA...SHSN.
Saturday: Moderate Operational Impact. Chance of SHRA...SHSN.
&&
.HYDROLOGY...
A moderate rainfall event continues through this evening. So
far, rainfall reports have ranged from 0.25" in the southern
Adirondacks up to 1.5" in the eastern Catskills. Additional
rainfall will occur through this evening before tapering off to
light showers overnight. Some urban/poor drainage flooding has
already occurred in Ulster county so that threat will also
continue into this evening. Flash flooding is not expected.
However, isolated thunderstorms are possible this evening which
may result in brief, heavy rainfall.
River rises are expected, but likely will remain within bank.
Current forecasts indicate river levels may reach action stages on
the Hoosic River at Williamstown, and also Stevenson Dam on the
Housatonic.
For details on specific area rivers and lakes, including observed
and forecast river stages and lake elevations, please visit the
Advanced Hydrologic Prediction Service /AHPS/ graphs on our
website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...JLV
NEAR TERM...JLV/Speciale
SHORT TERM...JLV
LONG TERM...KL
AVIATION...Speciale
HYDROLOGY...JLV
Area Forecast Discussion
National Weather Service Grand Rapids MI
1033 PM EST Mon Nov 30 2020
LATEST UPDATE...
Marine
.SYNOPSIS...
Issued at 300 PM EST Mon Nov 30 2020
- Light snow winds down tonight
- Dry and seasonable temperatures this week
&&
.DISCUSSION...(This evening through next Monday)
Issued at 300 PM EST Mon Nov 30 2020
-- Light snow winds down tonight --
Latest radar loop shows a persistent area of light snow over
southeast Lower MI. The back edge hasn`t moved much and stretches
from just west of Flint southwest to near Battle Creek. A
north/south oriented lake band was also noted moving south over
Berrien County.
The deepening low moving north across Pennsylvania will produce light
snow over the southeast CWA this evening before the snow tapers
off a bit. 12Z model data shows the low pivoting westward after
00z. This may throw a little more snow westward to the far eastern
CWA, but more likely it`ll remain just east of the CWA. Latest
HRRR shows the lake band remaining off shore of our CWA tonight
before it dissipates Tuesday morning. Additional accumulations are
expected to be less than an inch over Ingham/Jackson counties
tonight. Road cams show wet pavement with the light snow sticking
on the grass. However, as nightfall arrives and temperatures fall
below freezing, some slick spots will probably develop.
-- Dry and seasonable temperatures this week --
Once the low departs Tuesday night, high pressure will settle over
Lower Michigan through Saturday. We`ll see dry weather and highs
around 40 degrees, which is close to normal. The next chance of
precipitation is next Sunday when a short wave moves south across
Michigan from Ontario. Any precipitation we see from that wave,
however, looks to be light.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 814 PM EST Mon Nov 30 2020
MVFR clouds will likely hang in at most sites at least through
tonight. The clouds are largely lake generated and with a
northerly wind, that can open up breaks and lift ceilings
typically. Our forecast though is for mainly MVFR ceilings to
continue tonight, lifting to VFR levels on Tuesday. Winds will
remain gusty from the north tonight and the northwest on Tuesday.
Winds will generally be 10-20 knots sustained and gust at times
over 20 knots.
&&
.MARINE...
Issued at 1032 PM EST Mon Nov 30 2020
Gale force gusts are waning at this point and feel any Gale
conditions later tonight or Tuesday will be quite marginal. We are
therefore downgrading the Gale Warning at this time to a Small
Craft Advisory. The Small Craft Advisory will run through midday
on Wednesday as it will take awhile for the winds to diminish.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 1 PM EST Wednesday for LMZ844>849.
&&
$$
SYNOPSIS...04
DISCUSSION...04
AVIATION...Duke
MARINE...Duke
Area Forecast Discussion
National Weather Service Marquette MI
716 PM EST Mon Nov 30 2020
.SHORT TERM...(This evening through Tuesday)
Issued at 255 PM EST MON NOV 30 2020
Latest RAP analysis and GOES WV imagery show a deep trough seen at
500mb over the OH valley this morning, with high pressure off to the
west that will move over the Upper Great Lakes region throughout the
day with northerly flow continuing as well. Drier air at the low-
levels has been working into the area and will continue to do so
heading into the rest of the afternoon and evening hours. With the
drier air moving in, light lake-effect snow showers over the
northern wind belts will taper off as well but can`t rule out some
lingering flurries during the early overnight hours. Should see
little, if any, impacts but could be a few slick spots on secondary
roads. Winds will continue to decrease as the pressure gradient of a
developing low coming up the East Coast and that area of high
pressure. Upper Michigan will be in between both and could see some
breezy conditions over the east Tuesday afternoon. With that,
northerly flow will continue into Tuesday with that weak area of
high pressure over Upper Michigan for Tuesday and we should see more
sunshine as clouds will decrease in coverage but may not be too nice
as temperatures won`t warm up much. Went with 50th percentile for
highs with low to mid 30s. Lows tonight may be a bit tricky as a few
of the Hi-res guidance as lows, especially over the interior,
dropping to the low teens but given the winds will continue, total
snowfall that underachieved from previous storm system, and thinking
low cloud ceiling may linger past sunrise Tuesday morning, did not
go that low and capped lows over interior in the mid teens. If
clouds happen to clear out earlier than suggested, then lows may
need adjusted. Otherwise, pretty quiet through Tuesday evening.
.LONG TERM...(Tuesday night through Monday)
Issued at 217 PM EST MON NOV 30 2020
If you`re reading this wondering when you can finally break out the
snowmobile, well, I don`t have any good news for you. With the
exception of a cold front passage Sunday and some associated light
lake-effect snow (which at the moment looks pretty anemic) the long-
term period continues to look dry and 5-10 degrees warmer than
normal.
Tuesday night and Wednesday morning still look to get quite chilly
over the interior west. The only limiting factor is possibly a small
patch of cirrus moving through the flow which would limit
radiational cooling. Otherwise, mostly clear if not completely clear
skies, light winds, and some fresh snow should allow overnight temps
to plummet into the low teens or even high single digits. Continued
to rely on the MAV and MET guidance for lows this period. meanwhile
lows will probably stay in the mid to upper 20s east where onshore N
flow from Lake Superior will remain breezy around 10-20 mph through
the night.
Otherwise, with ridging remaining parked overhead the Northern
Plains and Upper Great Lakes, expect dry conditions through Saturday.
A weak mid-level trough pivoting around the closed upper low in
Quebec on Thursday will clip the region with some cloud cover, but
not bring enough moisture or lift for precip. Friday and Saturday
will have highs in the upper 30s across the region as 850 mb temps
warm to near +4 C. As discussed above, the next weather-maker is not
until Sunday when models are in decent agreement that a more
substantial wave will drop southward across the Upper Great Lakes.
This wave and the CAA behind it will brings temps back down to
around or below freezing for Sunday and Monday. Some snow showers
look possible in the N and NW flow LES belts but at first glance
this cold shot looks very similar to the one ongoing today, e.g.,
not impressive when it comes to moisture depth and potential for
anything more than light snow amounts.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 702 PM EST MON NOV 30 2020
Expect gradually improving conditions tonight into Tuesday at the
terminals as a high pressure ridge and associated drier air work
in from the northwest. MVFR cigs will scattered out to VFR around
midnight tonight at KIWD, around sunrise at KCMX and in the early
to mid afternoon on Tuesday at KSAW. A tighter pres gradient will
result in lingering gusty northerly winds at KSAW to 20 knots or
more through the period.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 255 PM EST MON NOV 30 2020
Winds will remain around 15-25 knots through the rest of today and
tonight. Some stronger wind gusts of around 30 knots with a few gale
force gusts of 35 knots over the far eastern part of the lake
Tuesday afternoon into late Tuesday night but then will fall back
between 15-25 knots through the rest of the forecast period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JH
LONG TERM...RJC
AVIATION...Voss
MARINE...JH
AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
910 PM EST Mon Nov 30 2020
.SYNOPSIS...
A strong cold front will sweep east offshore tonight, followed by
cold high pressure that will build into Southeast and Carolinas
through mid-week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 910 PM Monday...
Fractured cold front is evident in fine lines passing through the
Piedmont and coastal plain on radar imagery. Winds have weakened
significantly since the afternoon but continue to gust to 20kt
across the southern Piedmont and coastal plain. The deep upper
trough is apparoaching tonight and 120-180m 500mb height falls were
observed from ATL to BMH at 00Z. Upstream moisture isn`t
particularly deep, but strong forcing may be able to squeak out a
few light showers in the coastal plain after midnight. NAM/GFS
forecast soundings show moisture extending up to around -10C, but
recent RAP and HRRR runs do not support as much saturation, so
confidence is low. Regardless, the impact will be minimal with
temps falling into the mid/upper 30s very late tonight. With winds
still near 10kt in the morning, wind chills will drop into the upper
20s and lower 30s.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
As of 338 PM Monday...
The center of the strong low pressure system will move into NY
region with the cold front extending down into NC by sunset
reinforcing cold air advection across central NC. An upper trough
will provide sufficient forcing for ascent along with low level
lapse rates in excess of 8 degree C/km to produce a saturated layer
between 900 and 800 mb which could result in a few showers late
tonight into early Tuesday morning. The best area of precipitation
appears to be in the south across the Sandhills and southern Coastal
Plain counties. Lows tonight will be in the lower 30s in the NW
(where there will be drier conditions) and upper 30s/low 40s in the
SE. Tuesday will bring an abundance of sunshine but due to the
strong cold advection, highs will be in the low 40s to upper 40s in
the SE. Wind gusts up to 15-20kts on Tuesday will make it feel like
it is in the 30s all day. Lows Tuesday night will be the coldest of
the season. With clear skies and winds dying down in the evening,
good radiational cooling will result. Therefore temperatures across
the area will be in the mid to upper 20s, with possible cooler spots
in the lower 20s.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
As of 410 PM Monday...
Quiet weather, with mostly clear skies and light winds, is expected
on Wednesday and Thursday as 1025-1030mb surface high pressure
builds across the Southeast US. Rising heights will result in
increased low-level thicknesses and higher temperatures compared to
Tuesday. Forecast highs on Wednesday are generally in the lower-50s
and forecast lows in the upper-20s, which is still about 5-10
degrees below normal. By Thursday, temperatures will be close to
normal with highs in the mid-to-upper-50s, as the high pressure
system begins to move east and offshore.
The next upper low will dive south into the Southern Plains and NE
into the Great Lakes region, resulting in increasing precipitation
chances on Friday and Friday night. However, confidence during this
period is low as model guidance still varies significantly on the
timing of the system. The 12z GFS is actually slower compared to its
prior run while the 12z ECMWF is significantly faster. A good number
of ECMWF ensembles lean toward the fast solution as well, and WPC
guidance agrees more with the ECMWF. Thus have low chance POPs
across all of central NC on Friday and Friday night, decreasing to
slight to low chance on Saturday. Exact rainfall amounts with the
system are still uncertain but should be around half an inch or
less, not enough to cause any real hydro/flooding concerns.
Temperatures on Friday and Saturday will depend on system timing as
well, with the ECMWF solution resulting in a faster cold frontal
passage and cooler weather compared to the GFS solution. Regardless,
the cold air does not look to arrive fast enough for any frozen
precipitation across the area.
On Saturday night - early Sunday, the 12z GFS shows an additional
coastal low moving NE across the Carolinas, with more light
precipitation. However, the ECMWF does not have this feature and is
completely dry, as are the vast majority of its ensembles, so for
now just have slight chance POPs across most of the area. A
secondary reinforcing cold front will sweep through central NC on
Sunday night or early Monday, with a deep upper trough and much
cooler temperatures over the Eastern US to start next workweek.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
As of 706 PM Monday
High confidence in VFR conditions to start the TAF period. Wind
speeds have relaxed with loss of daytime heating, but still expect
westerly wind gusts up to 18 knots. Potential exists for a brief
period of MVFR ceilings at RDU/FAY/RWI between 07 and 12Z, though
confidence not as high. There appears to be enough lift and moisture
with the upper-trough passing through to warrant VCSH at FAY/RWI,
though not expected to be widespread during the entire time frame.
Otherwise, VFR conditions expected for the rest of the TAF period
with persistent westerly cross winds with gusts up to 24 knots in
the afternoon on Tuesday.
Outlook: VFR conditions expected through Friday. High pressure
settles in Wednesday and Thursday and wind speeds become light. A
storm system and associated frontal boundary bring a chance of rain
late Friday and Saturday with potential sub-VFR conditions.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...BLS
NEAR TERM...BLS
SHORT TERM...CA
LONG TERM...Danco
AVIATION...Kren