Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/18/17
Area Forecast Discussion
National Weather Service State College PA
821 PM EST Fri Nov 17 2017
.SYNOPSIS...
An intensifying storm system will move through the eastern Great
Lakes Saturday. followed by a strong cold front for Saturday
night. Cold gusty winds and some lake effect snow will then
affect the area Sunday into Monday. High pressure will then
bring improving conditions through the middle of next week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Clear skies will give way to increasing high clouds overnight
with the first of the rain forecast by the latest HRRR to be
entering my western stripe of counties right around sunrise.
Temperatures will continue to fall this evening, with readings
already freezing or below over the northern tier. While the
clouds will eventually put a brake on the fall as they thicken
up, some of the normal chilly nooks could be vulnerable to a
short period of spotty light freezing rain as the precip
overspreads the CWA. Right now the confidence is too low to
issue an advisory, but the potential will continue to be
monitored as the rain approaches.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
The storm system currently emerging from the front range of the
Rockies will deepen on its track into the eastern Gr Lakes
Saturday and Saturday evening.
The warm front south of the state will be very slow to advance
into the central ridge-valley region Saturday with the models
showing a strong cold air damming scenario setting up. With the
right entrance region of an upper jet streak sliding by just to
the north of the area, the thermally indirect vertical
circulation will support a strong NELY component to the low
level ageostrophic flow out of the north-northeast. With this
strong northerly component to the low level flow and precip
falling into an initially dry airmass contributing to further
stabilization through evaporational cooling, it points to a
chilly rain for the forecast area during the day, with the
steadiest stripe of rain likely over about the northern 2/3 of
the CWA.
Another concern for Saturday will be for an elevated
thunderstorm. SPC has us in its general outlook, but it`s hard
to find even a hint of elevated instability in the face of the
intense cold air damming. While I won`t rule it out in the
strong warm advection pattern that is expected to develop, I
think the probability is low enough to not mention at this
point.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
One-two punch of gusty West to Northwest wind, then a quick
transition to the first significant bout of Lake Effect Snow
this season across the NW mtns of PA in the wake of a strong
cold frontal passage Saturday night.
The synoptic set-up of a deepening low moving down the St
Lawrence River valley and a potent short wave trough aloft
swinging around the base of the longer trough is quite favorable
for strong winds.
The center of an area of very sharp pressure rises (10 mb/3
hours) moves ENE right over the region during the mid to late
morning hours Sunday. We could easily see Wind Advisory Criteria
with this type of fall/rise couplet passing directly overhead,
and possibly even a High Wind Watch/Warning scenario with west
to northwest gusts in the 50-60 mph range. It`s still far
enough out to look for consistency in this feature and decide
whether to go the High Wind Watch route at ~4th period.
The second punch is the deep/strong cold air advection with -10C
air at 850 mb crossing Lake Erie Water temps in the mid-upper
40s, which results in an extreme Lake-850 mb Delta T of 18C
Sunday afternoon and evening across the perennial snowbelt of NW
PA.
Winter Weather Advisory criteria will likely be reached from
this upcoming bout of LES, considering anticipated 4-8 inch
forecast snow amounts over an extended 24-36 hour period.
Elsewhere, much lighter snow amounts of a coating to 2 inches
will occur from sinuous bands of snow showers and briefly heavy
squalls that should make it well into the Central Ridge and
Valley Region and portions of the Susq Valley based on fairly
strong 35 to 45 kt nw winds in the deep and cold boundary
layer.
High pressure sliding by to our south will influence the
weather to start Thanksgiving week, bringing a couple of cool-
dry days. Temperatures will begin to moderate Tuesday with a
gusty SW flow expected to develop as potent sub-1000 mb low
pressure passes by across southern Ontario and Quebec. Tuesday
will be the lone day in the Mon-Fri period when 850 mb temps
will poke a few to several deg C above zero.
Though the jet stream will remain north of the region, a quick
moving trough will brush the region on Wed followed by a weak
shortwave Wed night, which will bring chance for periods of snow
showers (with light accums of a coating to 2 inches) back into
the NW zones, along with a return of slightly cooler air.
Flurries or brief snow showers will occur just SE of the
Allegheny Front.
12Z GFS and EC have trended into better agreement on a deepening
upper low across southeastern Canada or the NE U.S. over the
Thanksgiving weekend. Surface and 850 mb temps could be a few
deg colder than our upcoming cold outbreak later this weekend.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Widespread VFR expected overnight before conditions trend
steadily downhill into Saturday. Rain expected to overspread the
airspace 10-15z with a few pockets of freezing rain possible on
the leading edge over the north-central airspace. Confidence is
low on fzra risk and it would only last for a short duration.
Periods of rain will continue through the day with variable
cigs/vis ranging from low VFR to LIFR. Introduced LLWS at
western sites through midday with another period of LLWS
possible over the eastern 1/2 of the airspace ahead of a strong
cold front Saturday night. Southerly winds will increase
through the day with gusts 20-25kts by evening across the
western airspace.
Outlook...
Sun...Windy with sfc gusts 30-40kts from 270-310 degrees. IFR
snow showers NW trending MVFR central to VFR east.
Mon...MVFR cigs/sct -shsn psbl early NW 1/4.
Tue...Breezy. Mainly VFR.
Wed...Cold fropa. Snow showers possible NW.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...La Corte/Gartner
NEAR TERM...La Corte/Gartner
SHORT TERM...Dangelo/Gartner
LONG TERM...Lambert
AVIATION...Steinbugl
Area Forecast Discussion
National Weather Service Duluth MN
611 PM CST Fri Nov 17 2017
.SHORT TERM...(This evening through Saturday)
Issued at 242 PM CST Fri Nov 17 2017
Hazardous travel conditions continue across the Northland this
afternoon as a band of light to moderate snow due to 700-500 mb
frontogenetical forcing progresses eastward. Ahead of the FGEN
band of snow was a plethora of p-types, including snow, drizzle,
freezing drizzle, sleet, rain, and freezing rain in some isolated
spots. This precipitation will eventually diminish this evening as
a cold front associated with a sfc low pressure system, centered
over northeast Manitoba Canada, will scour out the moisture. RAP
and NAM model soundings indicate that some drier air will
infiltrate the 900-600 mb layer, which should inhibit any ice
production aloft as the cold front exits northwest Wisconsin. Due
to the lack of ice growth aloft, and the dry layer underneath the
ice producing layer, and some shallow moisture in the boundary
layer still existing in the soundings, decided to go more
drizzle/freezing drizzle over northwest Wisconsin. Cold air
advection behind the cold front will once again bring some chilly
air over the region, especially over north-central Minnesota, with
lows tonight ranging from the middle teens north to the middle to
upper 20s over northwest Wisconsin where the warmer air will
linger the longest.
Saturday will be much drier compared to today as sfc high
pressure will build into the region behind the cold front. Despite
the high pressure in place, skies should be partly to mostly
cloudy as we remain underneath a mid-level trough, which should
also keep our temperatures on the cold side, with highs Saturday
in the lower 20s along the International Border to the upper 20s
and lower 30s over the south. There may be some small chances of
snow showers along the International Border as a lobe of positive
vorticity advection embedded within the trough will translate over
our north. The better chances of snow could be on the South Shore
of Lake Superior as some lake effect snow showers could develop
by the afternoon. These chances shouldn`t be too high either, as
there are some questions regarding the amount of moisture
available, as well as more favorable delta-Ts holding off until
the evening. I still put in some slight chance/chance PoPs over
Iron and Ashland counties for Saturday afternoon, but didn`t want
to go any higher due to the uncertainty.
.LONG TERM...(Saturday night through Friday)
Issued at 234 PM CST Fri Nov 17 2017
The extended period will feature mainly northwest flow aloft with
several shortwaves moving through bringing chances for light
precipitation. No strong low pressure systems are forecast into next
week by either the GFS or ECMWF.
Colder air will continue to move south and east across the region
Saturday night. The low level winds will be northwest and should be
less than ideal for lake effect snow along the South Shore despite
favorable lapse rates. We have a chance for snow showers across
portions of Ashland and Iron Counties Saturday night with
accumulation of a dusting to around an inch. There may also be some
light snow or flurries along the International Border.
A low level ridge will move across the region Saturday night into
Sunday. Dry weather is expected for most areas Sunday through
Monday. Southerly low level winds Sunday night into Monday will
advect in warmer temperatures and highs Monday will be in the mid
thirties in the Arrowhead, to the lower to middle forties from the
Brainerd Lakes into northern Wisconsin.
A shortwave will bring a return to cooler air Monday night into
Tuesday with 850MB temperatures dropping from the single digits
above zero to teens below zero by 00Z Wednesday. Light snow showers
will be possible as the colder air moves in. There may also be lake
effect snow along the South Shore, especially Tuesday afternoon and
Tuesday night. The wind is northwest which isn`t supportive of heavy
lake effect snow accumulation. Highs Tuesday into Wednesday will
drop to the upper teens to upper twenties.
There will be a couple opportunities for light snow through the rest
of the week but significant snow looks unlikely.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 605 PM CST Fri Nov 17 2017
A front crosses tonight, but plenty of low level moisture will
lead to a variety of sub-VFR conditions. A few breaks here and
there may temporarily improve conditions to VFR, but largely
expecting low crud to linger. Moisture begins to erode as stronger
winds arrive Saturday and mixes the BL at least raising ceilings,
but will also have gusty winds at terminals to contend with.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 22 27 10 26 / 10 0 0 0
INL 15 23 6 24 / 10 30 10 10
BRD 24 28 12 34 / 10 0 0 0
HYR 27 31 13 28 / 30 0 0 0
ASX 29 32 17 29 / 30 20 20 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
SHORT TERM...JTS
LONG TERM...Melde
AVIATION...Wolfe
Area Forecast Discussion
National Weather Service Grand Rapids MI
715 PM EST Fri Nov 17 2017
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 317 PM EST Fri Nov 17 2017
Rain will move into the area beginning this evening. Isolated
thunderstorms are possible near and south of I-94 Saturday
morning. Otherwise, Saturday will be cool with highs in the 40s.
The heavier precipitation exits to the east early Saturday night.
This will be followed by colder air will spreading into the area.
Some lingering light rain showers will change to flurries towards
Sunday morning. Flurries are possible near and west of US-131 on
Sunday with highs only in the 30s. Afterwards, the coming week
looks mostly dry with highs generally in the 40s.
&&
.UPDATE...
Issued at 713 PM EST Fri Nov 17 2017
A couple of thunderstorms were over Lake MI at this time moving
quickly east. I have expanded the mention of storms in the
forecast...with the potential now roughly Interstate 96 and south.
I also increased the POPs. The potential for storms after midnight
gradually shifts southeast with time...which was also reflected in
this update.
UPDATE Issued at 602 PM EST Fri Nov 17 2017
We have added a mention of thunder for this evening over Lake MI
and additional areas south of I-96. This is based on thunderstorm
development over north central IL in a region of 500+ J/kg MUCAPE,
per RAP model estimates. This plume of instability and attendant
potential for thunder is expected to overspread far southwestern
Lower MI later this evening before peeling off to the southeast
Saturday morning.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 317 PM EST Fri Nov 17 2017
Little change to the previous forecast regarding precipitation
tonight into Saturday. The most likely scenario is that thunderstorms
will remain south of the area Saturday based on the SREF and
several convection allowing models. However, for the sake of
continuity, have kept a slight chance for the I-94 corridor,
especially since elevated instability isn`t always handled well by
the models. Precipitation totals are expected to range from
around 0.75 inches northwest to 1.5 inches southeast near Jackson.
A more uncertain but potentially impactful aspect of the forecast is
wind Saturday afternoon into Sunday morning. It is possible that
advisory headlines will be required with the strong post-frontal
cold advection, but this is a bit too uncertain to nail down now
with an advisory.
Finally, we expect lake effect rain showers to change over snow
Saturday night into Sunday, but any snow accumulations should be
curtailed be limited moisture depth into the DGZ. Some snow
showers/flurries will continue through Sunday.
.LONG TERM...(Monday through Friday)
Issued at 317 PM EST Fri Nov 17 2017
No big storms in the extended but a clipper and trailing cold front
could bring a quick shot of light snow on Tuesday afternoon or
evening followed by some lake effect snow showers into Wednesday.
Added some low chance POPs Tuesday through Wednesday and trended
temperatures a bit colder during this period. A clipper tracks north
of the Lakes Tuesday with enough low level convergence along the
trailing cold front to bring a brief period of snow or mixed rain
and snow late Tuesday afternoon into early Wednesday evening.
Strong cold advection follows behind the front with 850 mb temps
falling to minus 12C Wednesday night. Model soundings show inversion
heights around 7.5 kft AGL through Wednesday with northwest flow.
ECMWF is already showing warm advection by Wednesday afternoon which
would limit lake effect snow showers. Went with low chance POPS
across the favored NW flow lake effect areas Tuesday night and
Wednesday but it appears the highers chances will be Tuesday
night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 641 PM EST Fri Nov 17 2017
An area of showers and thunderstorms across portions of WI to IL
will continue to track east through the evening. Thus a potential
is there for some thunderstorms at the TAF sites. I added this to
the forecast for all sites. By 06z the axis of instability pushes
east of KLAN so less of a risk by then.
Widespread IFR and lower conditions will develop as we go through
the night. These low conditions will persist likely through
Saturday.
Colder air will filter in from the north Saturday afternoon and
evening. There are some indications that the airmass will become
cold enough for snow to mix by 00z. Given that there is some
uncertainty...I only featured a r/s mix. Will need to monitor
trends as a sooner transition to snow could lead to a period of
heavy wet snow.
Gusts over 25 knots from the north look likely to develop for
Saturday afternoon and evening.
&&
.MARINE...
Issued at 317 PM EST Fri Nov 17 2017
Will keep the small craft advisory intact with a transition to a
gale warning at 10 AM EST Saturday and lasting through Saturday
night. This timing is to align with the gale warning issued for the
open waters, although it is more likely that gale force gusts over
the nearshore waters will commence in the early afternoon. Gale
conditions across the northern marine zones could end as early as
Saturday evening.
&&
.HYDROLOGY...
Issued at 1042 AM EST Fri Nov 17 2017
Better confidence in precipitation forecasts has resulted in
additional river advisories this morning. Widespread rainfall will
affect Lower Michigan tonight into Saturday with precipitation
totals of 0.75+ inches by early Sunday morning. Amounts will
increase from north to south with the greatest totals expected
south of I-96.
River rises are forecast through the weekend and should stabilize
into next week as precipitation vacates the area. Though current
forecasts anticipate drier conditions, rivers will remain elevated
and responsive. Any changes to include additional precipitation
may need to be closely monitored.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 10 AM EST Saturday for LMZ844>849.
Gale Warning from 10 AM Saturday to 7 AM EST Sunday for
LMZ844>849.
&&
$$
UPDATE...MJS
SYNOPSIS...TJT
SHORT TERM...TJT
LONG TERM...Ostuno
AVIATION...MJS
HYDROLOGY...JAM
MARINE...TJT
Area Forecast Discussion
National Weather Service Houston/Galveston TX
918 PM CST Fri Nov 17 2017
.DISCUSSION...
Made just a few minor changes for tonight removing low chance pops
from northern counties late and just a few other slight tweeks to
sky condition and temp. Latest runs show very little rain with
front with HRRR really dry through its run out to 18Z and TTU WRF
dry until front gets fairly close to the coast. Think what will
play out...nothing more than a few sprinkles NW zones late morning
with perhaps a narrow line of relatively light showers developing
as the front gets closer to the coast and encounters slightly
deeper moisture as per precipitable water grids.
Reilly
&&
.PREV DISCUSSION... /ISSUED 550 PM CST Fri Nov 17 2017/
AVIATION...
Could see one more round of mainly MVFR ceilings develop overnight with
S to SSW winds 10-15 knots and occasionally gusty under a tightened
pressure gradient. The gusty winds will shift to the SW and W tomorrow
morning ahead of a cold front that will quickly works its way through
the area during the afternoon through very early evening hours. Winds
will stay gusty behind the front as they shift to the NW. Any ceilings
that developed tonight will lift and break - if not ahead of the front,
then definitely behind the front as drier air moves into the area. VFR
into tomorrow evening with weakening winds around the CLL and UTS areas
but staying on the breezy/windy side closer to the coast. 42
PREV DISCUSSION... /ISSUED 350 PM CST Fri Nov 17 2017/
DISCUSSION...
Daytime heating has allowed for some mixing in the
lower levels, dragging some of the higher wind speeds located
within the first few kilometers of the atmosphere, down to the
surface. This warming has also help to erode the thicker cloud
deck that was present earlier this morning. Strands of cumulus
clouds still linger over much of the region this afternoon.
Overnight, low level clouds will develop around 2,000 feet and PWs
will fall to around one inch. Forecast soundings still holding on to
a fairly strong cap at 850 mb across the region as well. Although
winds and wind gusts should lower early this evening, winds speeds
will stay elevate around 10 mph overnight. These faster wind speeds
should allow for a break from patchy fog tonight. Low temperatures
should remain in the upper 60s to lower 70s along the coast.
Saturday will bring the next cold front of the season which should
help drop temperatures to below normal climatology for this time of
year. Still a little uncertainty with the exact timing of the front,
but the models have been coming into more agreement in the more
recent model runs. The spread in the timing between the ECMWF and
the GFS has narrowed, and what was once a six hour discrepancy
has lessened, with the GFS solution making it to the coast
slightly faster. The pressure gradient will begin to tighten as
the trough enters the northern zone of our forecast area around
18Z Saturday. We should see most of the precip move through SE TX
between 18-00Z Saturday, clearing the coast shortly after 00Z.
With the model soundings significantly capped as the front pushes
through the region, decided to keep thunder out of the forecast
and only anticipating showers at this time. This system will not
bring much in terms of total rainfall with most of the
accumulation along the coast, but it will leave gusty winds in its
wake.
Both models show the wind shift to out of the north/northwest by 00Z
Sunday. Therefore, gusty conditions will prevail Saturday evening
behind the front especially along the coast, evident in the
forecast soundings. Will have to continue to monitor trends in the
models, as we could be flirting with wind advisory criteria
Saturday night into Sunday along the coast and specifically for
Galveston County. Behind the front cool and dry conditions will
prevail. The ECMWF is trending temperatures a few colder in
comparison to GFS. Leaned the forecast a little on the warmer side
closer to the GFS solution, based on consistency over the last
few model runs.
Additionally, depending on the timing of the cold front Saturday,
Saturday high temperatures could flirt with record values. The table
below contains both the normal and record temperature values for
Saturday November 18th. Behind the front high temperatures will
reach into the mid to upper 60s Sunday with low temperatures Sunday
night into Monday in the 40s to low 50s along the coast.
High pressure builds in behind the front and a warming trend will follow,
before the next cold front arrives late Tuesday into early
Wednesday. PWs rise to 1.00 to 1.25 inches on Tuesday as the next
front pushes through the region. Most of the precip with this
system will again be concentrated along the coast and over the
Gulf waters. This system will act to provide a reinforcing shot of
cooler air, which will leave high temperatures Wednesday and
Thursday in the mid 60s to low 70s, with lows in the 40s to mid
50s.
Hathaway
Climate...
Normal and Record Temperature Values for November 18th
Site Date Normal Normal High Max High Min
High Low Temp Record Temp Record
GLS 11/18 71 53 84 in 2016 73 in 1985
HOU 11/18 72 53 86 in 1973 73 in 1985
IAH 11/18 72 51 84 in 1973 74 in 1985
CLL 11/18 70 50 84 in 1986 71 in 1985
Hathaway
MARINE...
Expect onshore winds to increase to caution conditions tonight as
the surface pressure gradient tightens. The cold front should push
off of the coast sometime Saturday evening. Strong offshore winds
will develop behind the front with advisory conditions expected
Saturday night and Sunday. The thermal gradient right behind the
front will help lead to gusts to gale after the frontal passage
Saturday night. These could persist into Sunday morning but this
will depend upon the thermal gradient. Onshore winds return by
Monday. Another front is expected off of the coast Tuesday evening.
FIRE...
Elevated fire weather conditions are expected to develop for Sunday
and Monday as a very dry airmass moves over Southeast Texas. Even
though minimum relative humidity values will drop to between 25 and
30 percent area wide on Sunday afternoon and 30 to 40 percent most
areas on Monday, winds will likely be on the light side--probably 5
to 10 mph away from the coast on Sunday and under 10 mph on Monday.
Most concerned for Sunday with the drier conditions and winds
possibly reaching to between 10 and 15 mph in the coastal areas.
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 66 79 45 66 41 / 10 20 0 0 0
Houston (IAH) 69 84 48 67 43 / 10 20 0 0 0
Galveston (GLS) 71 82 55 66 54 / 10 30 10 0 0
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 6 AM CST Saturday for
the following zones: Coastal waters from Freeport to the
Matagorda Ship Channel out 20 NM...Coastal waters from High
Island to Freeport out 20 NM...Waters from Freeport to the
Matagorda Ship Channel from 20 to 60 NM...Waters from High
Island to Freeport from 20 to 60 NM.
&&
$$
Discussion...18
Area Forecast Discussion
National Weather Service Louisville KY
929 PM EST Fri Nov 17 2017
.Forecast Update...
Issued at 927 PM EST Fri Nov 17 2017
Starting to see some light showers show up on regional radars at
this hour in western portions of the CWA. These showers are
developing in response to isentropic lift and a strengthening low
level jet which is aiding to enhance a theta-e ridge over western
KY/southern IL. Coverage of showers should increase over the next
few hours.
Additionally, surface temperatures have been steadily going up over
the past few hours thanks to strong warm air advection, and think we
can safely assume we`ve hit our "low" temperatures for the evening
as temperatures steadily climb into tomorrow morning.
Only major update to the forecast was to start precipitation for
parts of central KY a few hours sooner given radar trends.
Otherwise, rest of forecast looks on track.
&&
.Short Term...(This evening through Saturday night)
Issued at 235 PM EST Fri Nov 17 2017
...Gusty Winds Saturday and Saturday Evening...
Low pressure now is over Kansas with a High pressure center to our
east. The gradient in between will tighten tonight, starting to
bring in some warmer and more moist air. It will be one of those
fall nights where the lowest temperature will be early this evening
and then steadily rise under those southerly winds. NAM is pulling
up a strong low-level jet of 60-70 knots over southern IN in the 06-
09Z time frame. GFS is weaker, with the RAP in between...around 60
knots. Would not be surprised to see some of those winds mix down
early in the morning...so the current advisory starting at 12Z looks
good.
That low-level jet should kick off some rains and perhaps isolated
storms along/north of the Ohio River before daybreak. After
daybreak, we should get more showery before a line of storms.
Precipitable water values come up to around 1.4 inches...which is
pretty high for this time of year. A more solid line of showers
should come through just ahead of the cold front in the mid to
late afternoon hours. Soundings indicate some limited instability
that should produce scattered thunder along that line. Stronger
winds are expected just behind the front, with gusts likely to
around 45 mph from the west and northwest. The gradient across our
area should relax pretty quickly behind this surge, so the timing
of the end of the advisory looks good for our region.
As for cloud cover behind the front, model RH fields in the 900-950
mb layer hold back moisture and keep that thin layer saturated
through daybreak Sunday. Previous forecast hung on to this cloud
layer through that time period and see no reason to deviate from
that at this point. Model statistical guidance has not been handling
this trapped moisture very well thanks to how thin the layer is.
.Long Term...(Sunday through Friday)
Issued at 235 PM EST Fri Nov 17 2017
After a couple days earlier in the week advertising a headache for
next week, the models have stabilized around a quiet solution for
the midweek. It looks like we`ll have a quasi-zonal flow, so
temperatures should moderate closer to normal and, at least for now,
Thanksgiving looks good. The only potential break in that zonal flow
comes Wednesday, but again this looks dry for now.
&&
.Aviation...(00Z TAF Issuance)
Issued at 620 PM EST Fri Nov 17 2017
LLJ will ramp up this evening and create some LLWS issues for all
TAF sites. Additionally, showers will expand in coverage overnight
from the west, and we`ll see cigs/vis degrade as the moisture works
eastward. Winds will also increase in strength out of the
south/southwest through the overnight hours, and remain quite strong
heading into Saturday morning and afternoon. A cold front will move
through the region tomorrow afternoon, and isolated to scattered
thunderstorms could be possible along the front, though confidence
in timing of storms and cold front remains low. Winds will switch to
the west/northwest behind the cold front and remain strong and gusty
Saturday afternoon and evening.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Wind Advisory from 7 AM EST /6 AM CST/ to 10 PM EST /9 PM CST/
Saturday for INZ076>079-083-084-089>092.
KY...Wind Advisory from 7 AM EST /6 AM CST/ to 10 PM EST /9 PM CST/
Saturday for KYZ023>043-045>049-053>057-061>067-070>078-081-
082.
&&
$$
Update...DM
Short Term...RJS
Long Term...RJS
Aviation...DM
Area Forecast Discussion
National Weather Service Melbourne FL
938 PM EST Fri Nov 17 2017
.DISCUSSION...High pressure across the Mid-Atlantic will shift
gradually offshore into tonight, with a relatively light low
level easterly flow veering to the southeast late. This onshore
wind flow will produce partly cloudy skies along the coast at
times as scattered clouds over the marine waters push onto the
coast, but otherwise skies will be clear to mostly clear
overnight for much of east central Florida. HRRR and local WRF
guidance continue to suggest some patchy fog development late
tonight, mainly northwest of the I-4 corridor so will leave
mention in the forecast. Temperatures will fall into the mid to
upper 50s for most areas tonight. Forecast is on track with no
changes planned.
&&
.AVIATION...Mainly VFR. Patchy fog may develop late tonight,
mainly northwest of the I-4 corridor, producing tempo IFR/MVFR
visibilities through early Saturday morning.
&&
.MARINE...Ridge across the Mid-Atlantic will shift offshore
tonight, with winds generally out of the east around 5 to 10
knots. Seas will be slow to subside, remaining in the 3-4FT range
along the immediate coast, and 4-5FT farther offshore.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 57 80 62 74 / 0 0 10 30
MCO 58 82 60 76 / 0 0 10 30
MLB 60 80 61 80 / 0 0 0 30
VRB 58 81 60 80 / 0 0 0 20
LEE 58 81 62 74 / 0 0 10 30
SFB 58 82 61 76 / 0 0 10 30
ORL 60 82 62 76 / 0 0 10 30
FPR 57 80 60 82 / 0 0 0 20
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Weitlich/Kelly
Area Forecast Discussion
National Weather Service Marquette MI
650 PM EST Fri Nov 17 2017
.SHORT TERM...(This evening through Saturday)
Issued at 335 PM EST FRI NOV 17 2017
...Heavy snow possible through early evening on the Keweenaw...
...Wintry mix will lead to slippery travel into Sat...
Large scale trough expands across Great Lakes through Sat. Stronger
shortwave and jet streak in base of trough will support stronger sfc
low spinning up from mid Mississippi River Valley late tonight to
the lower Great Lakes by late Sat aftn. Widespread precipitation
that moved in this aftn will diminish from west to east tonight as
sfc trough tied to low over northern Ontario continues to cross
Upper Michigan. Warm layer aloft 850-800mb or 3-4kft AGL led to
wintry mix of ra/fzra/sleet and snow earlier today but that mostly
has changed to rain now for central and east. Out west, already
seeing signs that cold air is slipping back into the region as rain
has changed back to snow at KCMX and has mixed with mixed with snow
at KIWD.
Attn is on h8-h7 fgen band in right entrance of jet streak causing
moderate to heavy precip over northeast MN and over western Lk
Superior. This forcing/precip slides across Keweenaw this evening.
RAP and HRRR are locked on to period of heavy precip, all snow,
through 00z with tapering to dz/fzdz afterwards. Will put out a
short duration winter wx advy for evening across Keweenaw Peninsula
for a brief period of moderate to heavy snow occurring right during
the evening commute.
Elsewhere, expect rain/snow mix over mostly scntrl and east forecast
area to gradually change to mainly dz or fzdz late evening into the
overnight hours. Will have to watch out for potential for some more
rain/snow scntrl and east as late as a bit after midnight as one
last push of precip tied to left exit of jet streak over central
Plains moves through. N to NW winds in wake of the sfc trough will
lead to best chance of dz/fzdz later tonight over higher terrain of
west, northwest and ncntrl Upper Michigan.
Other than the winter weather advy for evening on the Keweenaw
Peninsula, another SPS will be issued for the west half of Upper
Michigan to cover continual wintry mix and possible icy roads
tonight into Sat morning. Already hearing of icy roads in the
interior west U.P. as temps are just above freezing. Would expect
more of the same this evening and overnight as temps fall below
freezing.
Into Sat, precip for most of the day will be dz/fzdz, mainly west
and ncntrl higher terrain. Approaching shortwave from Manitoba and
northern Ontario that eventually helps carve out deeper troughing
and brings in colder air aloft on Sat night could also lead to
enough ice introduced aloft to lead to ptype becoming mostly snow in
the afternoon for the west half. Any ice and snow amounts on Sat
will be light.
.LONG TERM...(Saturday night through Friday)
Issued at 334 PM EST FRI NOV 17 2017
Main issues in the extended will be lake effect snow potential for
northwest wind snow belts Saturday night into Sunday and again
Tuesday into Wednesday. Travel weather into Thanksgiving looks to be
fairly quiet across much of the eastern CONUS outside of some light
lake effect snow potential.
Saturday night through Sunday: As the aforementioned stronger second
wave slides into the Upper Great Lakes Saturday night, expect colder
air to slide into the Upper Peninsula. This will act to lower the
DGZ enough to take away the freezing drizzle potential and keep
precipitation in the form of lake effect snow for mainly northwest
wind favored locations. Yet another wave is progged to slide across
the area late Saturday night into Sunday morning, which will help to
increase lake effect snow coverage. 850mb temperatures are expected
drop to the -14C to -17C range through this time period, giving
delta-t values in the 19C to 22C range. More than enough for lake
effect snow potential. Inversion heights are progged to be around
5kft to around 8kft when accounting for lake surface temperatures;
however, the sounding is lacking moisture in the 6kft to 8kft layer.
This points to mainly a light to possibly a moderate lake effect
event for this time period. The best chance of seeing the moderate
snow would be as the aforementioned waves move overhead Saturday
night into Sunday morning. Generally looks like 1 to 3 inches with
up to 5 inches possible in the northwest wind favored snow belts.
The greatest totals are expected over the higher terrain.
Sunday night through Monday night: As weak ridging slides into the
Upper Great Lakes and low pressure begins to approach form the
Northern Plains, winds will become westerly Sunday night and then
southerly for Monday into Monday night. This will effectivly push
the lake effect snow over Lake Superior before ending as warmer air
pushes in both at the surface and aloft.
Tuesday through the extended: Models are in good agreement that a
low pressure system will slide just north of Lake Superior early
Tuesday morning and into Quebec by Wednesday morning. This will drag
a cold front through the area during this time period and shift
winds to the northwest. 850mb temperatures are progged to drop into
the low to mid teens below zero, which would again be a good setup
for some lake effect snow for northwest wind favored snow belts
through at least early Wednesday afternoon. Details will have to be
ironed out as the system gets closer. At this point will stick with
a consensus of the models as this systems looks to be handled well
with the consensus. At this point, late Wednesday afternoon through
Thanksgiving looks to be fairly quiet with dry high pressure
building across much of the eastern CONUS.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 650 PM EST FRI NOV 17 2017
Although area of snow/rain will exit to the e and ne quickly this
evening, IFR and LIFR conditions will linger thru the night at
KIWD/KCMX/KSAW though KCMX may improve to MVFR late. In addition,
there may be some -dz or -fzdz at times with temps hovering around
the freezing mark. As gradually colder air arrives during Sat, cigs
will lift to MVFR at all terminals.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 335 PM EST FRI NOV 17 2017
Gales will diminish this evening as cold front to the south of low
over northern Ontario moves through. However, northwest winds
increase to gales again late Sat into Sat night. Not quite sure if
we`ll see prevailing gales though so will keep just gusts for now
and not issue a Gale warning. Winds diminish to 30 kts Sun into Mon
but more gales are possible late Mon night through Tue night as
active pattern continues.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Weather Advisory until 9 PM EST this evening for MIZ001-
003.
Lake Superior...
None.
Lake Michigan...
Gale Warning until 7 PM EST this evening for LMZ221-248-250.
&&
$$
SHORT TERM...JLA
LONG TERM...KEC
AVIATION...Rolfson
MARINE...JLA
Area Forecast Discussion
National Weather Service Tulsa OK
916 PM CST Fri Nov 17 2017
...UPDATE...
.DISCUSSION...
At mid evening...the cold front was positioned across Eastern
Colorado to Eastern Kansas with a dryline extending southwest from
the surface low through Western Oklahoma and Central Texas.
Scattered showers/convection had developed near the cold front
with gusty northerly winds behind the front. To the south and
east of the surface boundaries...partly to mostly cloudy skies and
gusty south- southwesterly winds were common across Eastern
Oklahoma and Northwest Arkansas. Temps also remained in the upper
60s to mid 70s over the CWA.
Through tonight...the cold front will continue to push southeast
and is forecast to enter into Northeast Oklahoma around 09z and
reaching the far northwest corner of Arkansas around 12z. The
ongoing showers/convection across Colorado/Kansas should continue
to shift eastward...remaining near the vicinity of the triple
point/surface low...into Missouri by Saturday morning. For now
will continue with pops below mentionable criteria...though latest
hrrr run tries to pull a few light rain showers near the
Oklahoma/Kansas border with the front.
Temperatures during the night ahead of the front should remain
warm with 60s/around 70 degrees holding common across the CWA.
Once the front moves into the CWA...drier air and gusty northerly
winds 20-35mph within a much colder airmass will help to drop
temps into upper 40s & 50s for lows across Northeast Oklahoma into
far Northwest Arkansas. Lows in the upper 50s/low 60s look to
hold for Southeast Oklahoma into West Central Arkansas. Have
adjusted hourly temps/dewpoints up slightly to slow the rate of
cooling underneath the cloud cover ahead of the front for the
evening update. Otherwise...current forecast seems to be in good
shape with the mentioned above. Also...will continue with current
wind advisory starting at 12z Saturday.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 52 56 34 59 / 10 10 0 0
FSM 62 64 36 59 / 10 10 0 0
MLC 58 61 35 59 / 0 0 0 0
BVO 49 56 30 59 / 10 10 0 0
FYV 56 59 31 53 / 10 20 0 0
BYV 57 60 34 52 / 10 30 0 0
MKO 55 58 34 57 / 0 10 0 0
MIO 50 53 33 56 / 10 20 0 0
F10 54 56 35 58 / 0 10 0 0
HHW 63 65 36 60 / 0 0 0 0
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...Wind Advisory from 6 AM to 5 PM CST Saturday for OKZ049-053>076.
AR...Wind Advisory from 6 AM to 5 PM CST Saturday for ARZ001-002-010-
011-019-020-029.
&&
$$
SHORT TERM...20
AVIATION.....18