Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/01/17
Area Forecast Discussion
National Weather Service Albany NY
1040 PM EDT Tue Oct 31 2017
Lake effect rain and snow showers will continue tonight
across the western Adirondacks with fair and dry weather elsewhere.
Overnight temperatures will be quite chilly, in the upper 20s to
lower 30s. More unsettled weather is expected to arrive tomorrow
afternoon, as a low pressure system tracks from the upper Great
Lakes into northeast Canada dragging a warm front and then a cold
front through our region.
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AS OF 1039 PM EDT...The latest KTYX and regional radar mosaic
shows a narrow lake effect band in the westerly flow off Lake
Ontario has weakened and become more diffuse in the last few
hours, as the subsidence inversion lowers and the boundary layer
winds continues to veer. The latest 3-km HRRR also supports this
weakening trend. A few snow showers or flurries are possible
across the western Adirondacks before they diminish. The skies
will become partly cloudy to mostly clear for a brief period of
time before some high clouds clouds increase from the Ohio
Valley. The winds will continue to become light to calm as temps
will fall in the chilly air mass into the upper 20s to
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
Clouds and low level moisture will be increasing throughout the
day Wednesday as the winds shift towards the southwest ahead of
the next low pressure system. This low pressure system is
expected to lift through the Great Lakes region and into
northeast Canada late Wednesday into Thursday, dragging a warm
front through the region. Showers are expected ahead of this
warm front beginning Wednesday morning. Temperatures on
Wednesday will remain quite chilly, in the low 40s to near 50
degrees under cloudy skies.
Shower chances continue overnight
Wednesday night as the warm front lifts northward through the
region. The best chance for steadier rainfall will be across
the Adirondacks, Lake George-Saratoga Region and the Mohawk
Valley, closer to the better dynamics tracking north and west of
the region through Thursday morning. Temperatures overnight may
be tricky depending on the timing of the warm front passage
compared to the shower activity, but they are currently forecast
in the upper 30s to low 40s.
Rain should lift north and east of the region by Thursday
afternoon as southwesterly winds increase. Temperatures during
the afternoon will feature a return to above normal values, in
the upper 50s to mid 60s.
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
We begin the long term with a broad and moist southwest flow regime
ahead of an approaching cold front through Thursday night. Low
level jet magnitudes approaching 50kts are in the forecast per
global model consensus which should keep considerable cloud coverage
and the threat for periods of wet weather (showers and/or drizzle).
The best chance for showers will be closer proximity to the front
which is progged to remain north and west of Albany.
Cold frontal passage is well timed per global model consensus to
occur Friday morning. Then cold advection will pursue in the wake
of frontal passage with increase west-northwest winds. Probabilities
of precipitation will diminish from northwest to southeast through
the day with mainly dry conditions expected through the afternoon
hours. Thereafter, 1035mb surface high builds in from just north of
the Great Lakes into the northeast corridor through most of
Then confidence goes lower Saturday night as the ECMWF remains the
most aggressive with a surge of warm advection and isentropic lift
for periods of light precipitation Saturday night. The GFS and GGEM
are in closer agreement with a more gradual increase in broad warm
advection as we will hold off on too much influence from the ECMWF
at this time. Regardless, seems clouds will be on the increase
again through the weekend with an increase in wet weather conditions
starting mainly Saturday night into the day on Sunday.
Another cold front approaches Monday where the chance for showers,
perhaps a rumble of thunder as Showalters drop to near 0C, will be
on the increase. Global models are in somewhat good agreement with
this scenario as we will keep PoPs a bit higher than climatology.
Temperatures through the period will average near to a bit above
normal with precipitation near to above normal.
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
High pressure will briefly ridge in over the region tonight. The
sfc high will quickly shift east of New England in the morning,
as a mid level disturbance and a warm front approach from the
Ohio Valley and Mid Atlantic States with a chance of some
showers late in the afternoon thru the overnight period.
Expecting mainly VFR conditions for KGFL/KALB/KPSF/KPOU
prior to 19Z/TUE. The clouds will decrease early this evening
except at KGFL where some stratocumulus due to the lake effect
fetch may linger until 04Z-08Z. Some thin high clouds will
increase after 06Z for all the terminals. The clouds will
gradually thicken and lower from the south/southwest to the
north/northeast across the region with bases in the 10-15 kft
AGL range by 13Z-15Z/TUE. The clouds will continue to thicken
and lower by the afternoon with low to mid level warm advection
in advance of the warm front. There is a chance of light rain
showers in the afternoon especially after 19Z-21Z and PROB30
groups were used at all the TAF sites. We did place some high
MVFR cigs/vsbys at KPSF in the PROB30s, but kept all other
sites VFR at this time with bases in the 3.5-5 kft AGL range
prior to 00Z/WED.
The west to southwest winds of 4-7 kts winds will become light
and variable at 3 kts or less/calm prior to midnight. The winds
will be from the south to southeast at less than 10 kts in the
late morning thru the afternoon.
Wednesday Night: Moderate Operational Impact. Scattered SHRA.
Thursday: Moderate Operational Impact. Scattered SHRA.
Thursday Night: Moderate Operational Impact. Chance of SHRA.
Friday: Moderate Operational Impact. Chance of SHRA.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: Moderate Operational Impact. Chance of RA.
Sunday: Moderate Operational Impact. Chance of RA.
Scattered rain and snow showers will continue across the
western Adirondacks through Tuesday night with a cooler and more
seasonably airmass in place. Overnight temperatures will be quite
chilly, in the low 30s. More unsettled weather is expected to arrive
Wednesday afternoon as a low pressure system tracks from the upper
Great Lakes into northeast Canada dragging a warm front and then a
cold front through our region.
Most of the rivers, creeks and streams were receding after
receiving substantial rainfall Sunday and Sunday night. Mainly
dry conditions are expected tonight except across the western
Adirondacks where some lake effect snow and rain showers are
expected. More unsettled weather is expected to return Wednesday
afternoon into Thursday night. Rainfall amounts at this time
appear to range from a tenth of an inch southeast to three
quarters of an inch northwest.
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.
Area Forecast Discussion
National Weather Service Gaylord MI
1053 PM EDT Tue Oct 31 2017
Issued at 1044 PM EDT Tue Oct 31 2017
WSW Lake effect now ongoing as expected across northern Emmet
County, northwest Cheboygan and southern portions of Mackinac and
Chippewa Counties. The most intense activity is across northwest
Emmet County where several inches of accumulation are expected by
early morning...hence the winter weather advisory. One worry is
with winds continuing to slowly back into the south southwest...a
smaller portion of the advisory area will be affected. Will leave
headline as is...since the snow will be of the very greasy variety
and it`s the first "event" of the season. Besides the lake effect,
nothing of note going on across the remainder of the forecast
.NEAR TERM...(Tonight through Wednesday)
Issued at 411 PM EDT Tue Oct 31 2017
...Lake effect snow to reinvigorate over the tip of the mitt...
High impact weather potential...potentially healthy snowfall amounts
tonight in northern Emmet Co and surroundings.
High pressure will rapidly transit the Ohio Valley this evening. Our
low-winds will back considerably in response, becoming sw by late
evening and south for Wednesday. Diurnal heating has done its usual
thing to lake effect, with reasonably broad coverage of cellular
convection. This is still snow in interior sections, mixy in spots
toward Lakes MI/Huron. Precip trends are the main concern.
As we head toward dusk, diurnal instability wanes. Showers outside
of lake effect regimes will fade out, while within them showers will
attempt to reorganize into bands. With sw flow arriving, the prime
area of concern will be centered on the tip of northern lower MI.
Our air remains plenty cold enough for lake effect, and for snow at
that. We won`t dislodge the cold air until late in the day on
Wednesday. In the meantime, we have a fairly lengthy period of
stable sw flow from 03z to 09z tonight.
Hi-rez short-term guidance really latches onto this event. Both HRRR
and Rap runs crank out near or over half an inch of liquid QPF in
parts of northern Emmet Co tonight. (A recent HRRR run - not the
most current - had a 0.85" bullseye). One difference from last night
is that we are targeting an area outside of the high elevations. The
BL should be warmer, and snow-liquid ratios lower. That`s also the
end of a very long fetch over a warm Lake MI - how warm will the
marine layer be? That said, temps in that area are still bottoming
out when precip is occurring (Mackinac Isl crashed to 35f during
a recent snow shower). And PLN at 39/31 presently would support
wet snow via wet bulb effects.
Am going to post a one-county winter wx advis tonight for Emmet,
with 2-6 inches of potential snowfall north of Harbor Spgs.
Snowfall totals of around 3 inches will lead into the St Ignace
area, far nw Cheboygan Co, and small parts of eastern Chip/Mack
Cos. The impacted areas and snowfall amounts are not large enough
to warrant adding those counties to this advisory.
For Wednesday, continued backing of the low-level flow will push
snow showers off of Lake MI further west, into central and western
Mack Co and eventually out to ISQ. A decrease in intensity is
expected (especially in the afternoon), as continued warm
advection erodes and shallows-out instability. This will also
introduce more of a rain-snow mix into leftover precip. Will keep
snowfall amounts less than an inch in upper MI. Otherwise, spotty
rain/snow showers will also impact the nw lower MI coastline,
especially in the morning. Better synoptic forcing and more
widespread precip with the next system looks to arrive just after
Min temps tonight in the 20s to around 30f. Max temps Wednesday
near 40f to the mid 40s.
.SHORT TERM...(Wednesday night through Friday)
Issued at 411 PM EDT Tue Oct 31 2017
...Widespread precipitation Wednesday night...
High Impact Weather Potential...Minor slushy snow accumulations
possible Wednesday evening across interior northern Lower and
Pattern Synopsis/Forecast...A potent shortwave and developing
surface low will track through the Upper Midwest and then cut across
northern Lake Superior Wednesday night into Thursday. Vigorous warm
air advection will develop Wednesday evening and continue overnight
as a ~50 knot low level jet passes just southeast of the forecast
area. This will pump increasing moisture into the region with PWATs
climbing above 0.7" for much of northern Lower overnight. Together
these features and the increased moisture will produce widespread
precipitation overnight across northern Michigan as they cross the
region. A cooler, drier airmass will progressively filter back into
the area on Thursday as the system departs and a large Canadian
surface high pressure builds in behind it.
Primary Forecast Concerns...Precip chances and precip-type evolution
Wednesday night into Thursday.
Any lingering lake effect showers over western Chip/Mack counties
should come to a fairly quick end Wednesday evening as warm air
advection ramps up and increasing low level flow backs to the SSE.
Bulk of the more widespread precip looks to overspread northern
Michigan after 8pm Wednesday and eventually exit our eastern
counties towards daybreak Thursday. At time of onset, forecast
soundings across northern Michigan are largely sub-freezing except
for an initially dry surface layer. Wet bulb zero heights are quite
low to start across eastern Upper and interior northern Lower, so
think precip will begin as snow or a rain/snow mix in these areas.
Near the coasts, precip should largely stay just rain. As WAA
intensifies from south to north overnight (leading to a nocturnal
temperature rise after midnight), soundings gradually warm and low
levels become almost isothermal. This will result in a south-to-
north transition to just rain, but until then it looks like it may
snow enough to produce a slushy inch or so of accumulation over
interior northern Lower, perhaps slightly higher amounts across
interior eastern Upper.
The LLJ and strongest WAA will lift off to the northeast around or
shortly after daybreak Thursday, taking the bulk of the heaviest
precip with them. However, scattered light rain showers will be
possible during the day as some mid-level energy and a somewhat
diffuse cold front work through the area. Additionally, it looks to
get cold enough aloft to generate enough lake instability over Lake
Superior to introduce lake effect rain showers over eastern Upper
late Thursday afternoon/evening. Influx of drier air as high
pressure noses into the area Thursday night will eventually bring an
end to all remaining precip overnight and allow for a cool but dry
day with some sunshine.
.LONG TERM...(Friday night through Tuesday)
Issued at 411 PM EDT Tue Oct 31 2017
High Impact Weather Potential...Minimal.
Unsettled weather returns as we head into the weekend with the large
surface high departing. Widespread warm air advection aloft out
ahead of a developing low east of the northern Rockies will kick off
a band of precip over the Upper Great Lakes late Friday night into
Saturday. As the parent low ejects towards Hudson Bay early next
week, a trailing cold front will eventually cross northern Michigan.
So, looking like more wet weather at times through the weekend and
cold enough nighttime temperatures to support some nocturnal snow
showers, mainly inland. Another incoming surface high looks to
dry things out a bit for most Monday into Tuesday, but a cold
airmass aloft may support additional lake effect showers off Lake
Superior. Temperatures will briefly warm a bit Sunday into Monday
with daytime highs in the 50s for much of northern Lower. Cooling
back down by Tuesday.
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 752 PM EDT Tue Oct 31 2017
Lake effect showers gradually getting shunted towards the Straits
this evening as winds shift SW. PLN will be most impacted of all
the terminals overnight as a band of lake effect snow is expected
to develop in its vicinity. Looking like SW flow will carry the
band over PLN through around 06Z, before winds subtly become more
southerly and likely shunt the band farther north through
daybreak. Temporary MVFR vsby and cigs possible with the heavier
snow showers. MBL and TVC will likely see some transient snow
shower activity overnight and should generally remain VFR.
Should be dry on Wednesday with somewhat breezy southerly winds in
Issued at 411 PM EDT Tue Oct 31 2017
Ongoing small craft advisories are winding down in some waters,
though will reassess shortly as to whether any extensions are in
order. Advisory-level conditions are expected to return to at
least Lake MI by Wed afternoon, as high pressure moves east and
stronger southerly winds returns.
MI...WINTER WEATHER ADVISORY until 8 AM EDT Wednesday for MIZ016.
Area Forecast Discussion
National Weather Service Spokane WA
849 PM PDT Tue Oct 31 2017
Clear skies tonight will allow temperatures to fall into the 20s
early Tuesday morning. A much cooler, wet and unsettled weather
pattern will develop Wednesday night and will continue through
the weekend bringing heavy snow to the mountains and the northern
valleys Wednesday night through Saturday.
After a dialog with neighboring forecast offices concerning the
18Z nested NAM model and some of the HRRR runs depiction of
potentially intense snowfall band oriented along the cold front
dropping down through Montana and pushing into parts of North
Idaho it was decided a winter weather advisory advertising a
localized potential of 1-3 inches of snow for Idaho zones 1 and 4
should be tacked onto the winter storm watch for the storm system
moving through Wednesday night through Friday morning. /Pelatti
00Z TAFS: Northwest to southeast oriented jet stream sags over
the aviation site tonight and lingers overhead through a good
portion of tomorrow. The strong northwest winds aloft brought
about by this jet stream positioning may cause low level wind
shear issues at times during the overnight and morning hours.
During the afternoon and evening hours the winds should mix down a
reasonable amount to decrease the low level wind shear. Otherwise
some light rain showers over the TAF sites tomorrow during the
day starting as early as 12Z Wednesday but more likely after 15Z
Wednesday may bring MVFR ceilings on into tomorrow afternoon.
.PRELIMINARY POINT TEMPS/POPS...
Spokane 35 49 35 42 34 36 / 10 20 70 90 100 90
Coeur d`Alene 34 47 34 40 33 35 / 10 30 70 100 100 100
Pullman 39 50 36 46 38 42 / 0 40 50 50 90 100
Lewiston 42 57 40 51 41 46 / 0 40 50 30 70 90
Colville 32 51 32 35 26 35 / 20 20 60 100 100 100
Sandpoint 31 46 31 33 28 32 / 20 80 80 100 100 100
Kellogg 34 43 33 39 33 34 / 20 80 90 100 100 100
Moses Lake 34 57 33 50 37 45 / 0 20 20 30 50 50
Wenatchee 39 55 36 48 35 40 / 0 10 20 60 70 50
Omak 34 54 33 37 31 36 / 10 20 20 90 100 60
ID...Winter Weather Advisory from 8 AM to 1 PM PDT Wednesday for
Central Panhandle Mountains-Northern Panhandle.
Winter Storm Watch from late Wednesday night through Friday
morning for Northern Panhandle.
WA...Winter Storm Watch from late Wednesday night through Friday
morning for Northeast Mountains-Okanogan Highlands.
Area Forecast Discussion
National Weather Service Shreveport LA
913 PM CDT Tue Oct 31 2017
Light to moderate rainfall has pushed eastward from central TX to
across eastern TX and into deep east TX and northern LA late this
evening. Intermittent lightning was noted just west of the
county warning area though it can not be ruled out. There is a
wane in precipitation across southeast OK and extreme northeast
TX and southwest AR late this evening, however near term high-
resolution computer models such as the HRRR suggest additional
precipitation will develop and fill in overnight. Due to recent
radar and expected trends, have gone ahead and increased POPs to
the definite category /where areas are experiencing rainfall/ and
dropped POPs off a bit to slight chance/low end chance category
with lack of rainfall /before 06Z/. After midnight, rain should be
area-wide if the HRRR is indeed correct, which seems to be valid
given continual development of showers upstream across central TX.
Otherwise, tweaked the surface temperatures as it was cooling off
a bit faster than expected, but should start to level off due to
the extensive cloud cover. Subsequently tweaked the dewpoint
temperatures and relative humidity values. Have a safe and fun
.PREV DISCUSSION... /issued 737 PM CDT Tue Oct 31 2017/
For the 01/00Z TAF period, a mix of low VFR/MVFR cigs to begin the
period and they will further deteriorate through this evening and
overnight hours as rain showers increase in coverage and intensity.
Vsbys will also drop in heavier showers and with some fog forming
as a warm front pushes back northward after midnight. This may also
lead to some embedded thunderstorms accompanying the widespread
showers through Wednesday morning. Cigs/vsbys will likely not show
much improvement until Wednesday afternoon as the showers gradually
begin to exit the region. Some sites may be VFR conditions return
late in the period, mainly in east Texas where convection will end
a bit earlier. Winds will be mostly light and variable overnight
with the front lingering south, and then they will trend SE with
the returning warm front shifting north with speeds increasing to
near 10 kts.
PREV DISCUSSION... /issued 521 PM CDT Tue Oct 31 2017/
Patchy lgt rain beginning to increase across area, with larger
area of rain and embedded convection slowly movg across I-35
eastward towards the area. Saturation from the top down is
occurring so rainfall to begin as lgt and gradually increase.
Also, a warm front over se TX into central LA may shift slightly
nwd, providing additional focus for enhanced rainfall and provide
trigger for tstms as stg low lvl shear and decent mid lvl lapse
rates already in place. One to near two inches of rain is possible
overnight into early Wed before dry slotting occurs over at least
a portion of the area, but leaving in low pops across eastern
portions of area thru Thu. Meanwhile, a stg upper lvl ridge
building over nrn MEX will create upper level difluence over
eastern portions with an overall warming trend as highs climb
into the 80s over the wknd. Instability will increase Friday but
with more limited moisture and expect discrete but widely
scattered tstms later Friday before mid lvls begin to warm and
continue to dry out making for a mostly rain free remainder of
.PRELIMINARY POINT TEMPS/POPS...
SHV 50 74 65 82 / 100 70 20 20
MLU 55 73 65 82 / 60 80 30 30
DEQ 44 67 57 80 / 60 30 10 20
TXK 47 66 63 80 / 80 50 10 20
ELD 48 69 63 80 / 100 70 20 30
TYR 51 74 66 83 / 80 40 10 10
GGG 50 74 64 82 / 100 60 10 10
LFK 58 74 67 83 / 100 70 10 20