Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/20/18
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
612 PM EST Fri Jan 19 2018
An amplifying longwave ridge over the central United States and
increasing stability aloft will maintain relatively quiet weather
throughout the period. Models are having a difficult time
forecasting the amount of saturation that will occur in the near
surface layer Saturday morning as there is some projected low level
moisture advection from the south. With snowpack in place, model
boundary layer schemes are very suspect and low confidence exists.
Rap is much less bullish on prospects for fog development and very
low cig heights. Have used the Rap as a guideline and instead, will
call for a prevailing MVFR HZ at all sites around/after daybreak
with MVFR cig heights taking hold throughout the day.
/DTW THRESHOLD PROBABILITIES...
* Moderate to High for cigs aob 5kft after 12Z Saturday.
Issued at 251 PM EST Fri Jan 19 2018
Upper level ridge spilling over into the Great Lakes region today.
12Z Minneapolis sounding revealed very warm air/near record, as 850
mb temp checked in at 11 C, and this narrow axis of warm air will be
sliding through southeast Michigan this evening as a dry cold front
slides through the northern Great Lakes tonight. Sufficient
mixing/elevated southwest surface winds through the night expected
to hold temperatures around 30 degrees.
Remnant/weak 850-700 MB theta-e ridge axis sliding south through the
CWA on Saturday, with renewed 850 mb moisture/theta-e coming out of
the Midwest late in the day. Maxes will be determined by amount of
low clouds around tomorrow, as there is a major difference between
12z NAM/GFS 925 mb moisture/temps vs 12z Euro/Regional GEM. Could
see maxes ultimately end up anywhere from the mid 30s to mid 40s.
Preference will be to lean toward partly sunny skies and milder temps
(lower 40s), as ARW is not nearly as bullish with the 925 MB
Low level jet (925-850 MB) over the Ohio Valley Saturday night
veering, and becoming a bit more west-southwest, and thinking the
low level moisture sufficient to generate drizzle/light rain will
struggle to make much inroads across the southern Michigan border
through Saturday Night. None-the-less, if a sufficient depth of
saturation occurs, with temperatures flirting around freezing mark,
a slight chance of light freezing rain/drizzle appears warranted
along/south of M-59. Higher dew pts coming over the frozen ground on
Sunday will likely result in some fog, but dew pts only expected to
be in the mid 30s, probably not high enough to support dense fog,
prefer values closer to 40 degrees, but also the amount of snow cover
remaining, if any, will factor in as we head into Sunday evening.
Aggressive height falls spreading into the Plains on Sunday, and
over the Midwest/Iowa by Monday Morning. Strengthening surface high
over northern Ontario (1036-1038 MB) with the tightening low level
baroclinic zone over Lower Michigan will present a better
opportunity for freezing rain along/north of M-46 late Sunday night
as drier sfc-925 mb easterly flow undercuts the moisture/warm
Low pressure traveling northeast from IA/MO into Michigan Monday 12Z
to Tuesday 12Z will bring the likely chance for precipitation
throughout both days. There are slight discrepancies regarding the
track of the low as it traverses across Michigan, with the GFS/GEM
taking the low over northern lower Michigan, while the ECMWF run
places the low across central lower Michigan and into the thumb.
Despite the discrepancies, 850 mb temperatures averaging 4 - 6 C and
surface temperatures peaking in the low to mid-40s will support rain
for precipitation seen throughout Monday. As the low continues to
push northeast into Ontario, cold Canadian air will quickly wrap
around the western side of the low, dropping 850 mb temperatures
down to an average of -5C by 12Z Tuesday. As a result, precipitation
is expected to transition from rain, to a rain snow mix, and
eventually all snow throughout the Tuesday morning hours. Light snow
will be possible throughout Tuesday, before tapering off by early
Wednesday as low pressure pushes into the New England.
Temperatures will return to season to slightly above seasonal norms
behind the low, with daytime highs peaking in the mid to upper-30s
through the mid-week period. Surface high pressure and ridging aloft
will help keep conditions dry through this time, with a late week
developing low pressure system bringing the next chance for
precipitation by Saturday.
High pressure centered over the southeastern US will dominate the
weather over the Great Lakes for the next couple days. Southwesterly
flow on the northwestern edge of the high pressure will persist
through today with winds staying generally around 30 knots or less.
Winds will back to the south/southeast by Sunday afternoon and
evening as the next low pressure system approaches and also brings
increased chances for rain to close out the weekend. Rain chances
continue on Monday with winds becoming elevated as the center of low
pressure system enters the Great Lakes region. Anticipate winds to
be somewhat tempered by the warm air advection with this system
through the weekend, but winds could pick up out of the southwest
when cold air rushes in on the back side of the system.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
You can obtain your latest National Weather Service forecasts online
Area Forecast Discussion
National Weather Service Gray ME
754 PM EST Fri Jan 19 2018
A weak ridge of high pressure will build into the region today
with temperatures a bit warmer than yesterday. A milder flow
and above normal temperatures follow for the upcoming weekend. A
storm system moving into the Great Lakes will bring wintry
precipitation Monday into Tuesday with temperatures warming. A
cold front Tuesday night brings colder air back into the region.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
700 PM Update...
Sharp temperature inversion over the region this evening
keeping low level moisture trapped over the area and will be
slow to clear overnight. Increasing southwesterly boundary
layer winds beginning to push this moisture out of southwest New
England and this trend will continue through midnight and the
early morning hours with clearing from southwest to northeast.
High clouds pushing into the region from the northwest will be
around overnight and through the first half of Saturday. Some
light returns on radar showing up across southern Quebec in weak
over-running with surface obs showing scattered snow showers.
HRRR bringing a brief period of snow showers through northern
zones after midnight which may produce a quick dusting in places
but nothing too impactful. Have made a few tweaks to temps/tds
but temps showing little change and should be steady or slowly
rising overnight. No other changes to current forecast attm.
Weak short wave that brought snow showers to the north earlier
today has moved offshore and will be replaced with milder WNW
flow aloft. Cloudy skies prevail this afternoon with 20s and 30s
across the region. Warmer temperatures are in place to the SW
over PA and NJ where stronger southerly winds were in place in
the vicinity of a forming surface trough. To the north, low
pressure was traversing through Ontario Province...and this may
trigger a few light snow showers along the international border
overnight. Weak short wave that brought snow showers to the
north earlier today has moved offshore and will be replaced with
milder WNW flow aloft. Overnight lows will drop into the lower
20s north to mid 20s south before rising as a non-diurnal
temperature trend is expected with warm air advection regime
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
The morning will be followed by a weak cold front and modest
cold air advection. Nevertheless, expect some melting to occur
with readings in the 30s in the north to the mid 40s/near 50 in
the south. There will be a continued threat for scattered snow
showers in the mountains. This will mainly be across the
northwest facing upslope regions of the higher terrain. Saturday
night colder air will filter in to the north with temperatures
dropping into the teens...elsewhere we`ll see lows in the 20s.
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Other than the overall theme of milder than normal in the
extended...focus is mainly on next precip event.
Trof is forecast to move onshore across the Wrn CONUS by
tomorrow and track across the country with broad Sly flow ahead
of it. At the same time high pressure is forecast to build
across Quebec just ahead of the approaching storm. This general
evolution is supported by ensemble guidance...with differences
in positioning but consistent timing. The high pressure building
in N of the approaching low, and positioning off to the NE is
favorable for colder surface temps than currently forecast by
NWP. I continued the trend of undercutting guidance for the Tue
high temp with non-diurnal trend of slow warming Mon night.
This brings a mixed bag of precip into play...especially Tue.
Snow, becoming sleet, freezing rain, and even rain is all on
the table. That being said. regional RAOBs have not yet had a
chance to sample this wave over the Pacific, and that may change
model guidance Sat and especially Sat evening. The GEFS and
ECMWF EPS remain at odds regarding the location of that high
pressure...which will be critical to ptype forecasts. Clustering
of ensemble members hints that a S/WV trof that amplifies
sooner over the Wrn CONUS tends to favor the colder solutions by
the time it reaches the Northeast...possibly due to WAA
processes having maxed out well to our W rather than nearby. So
for I see no reason to deviate significantly from the previous
forecast...which seemed reasonable.
Beyond that event, high pressure builds back in with return
flow gradually moderating temps upward thru the end of the week.
.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
Short Term...Mainly VFR conditions across the region, however
northernmost regions such as HIE and HIE will likely have a
period of MVFR conditions in lower stratus and -SHSN. Gusty SW
winds will develop Saturday.
Long Term...Generally VFR conditions set to prevail to end the
weekend. High pressure will build N of the area while the next
storm system approaches from the W. High is well positioned to
keep cooler solutions in play...but widespread IFR conditions
are looking fairly likely. All ptypes are a possibility...with
SN at the onset Mon night...transitioning from SW to NE. Some
coastal terminals...even as far N as MHT...may change to RA
before tapering off Tue afternoon/evening. Will have to monitor
LLWS as well...with light to NE surface winds...and SW flow
aloft across Srn parts of the forecast area. Wly flow dominates
Wed...with MVFR clouds and SHSN in the mtns near HIE lingering.
Short Term...Winds and seas will increase late tonight and
Saturday. There will be a period of SCAs, especially out over
the outer waters. Winds may approach gales, but we will only see
2-3 hours of them over the far outer waters. Therefore feel SCAs
were more appropriate.
Long Term...Winds and seas will increase ahead of the next
approaching storm system Mon night into Tue. Gale force wind
gusts are possible outside the bays...with SCA conditions likely
continuing into the end of the week.
Several points along area rivers remain at high water
levels...including the Kennebec River at Augusta. Please see the
Flood Potential Outlook (ESFGYX) for more information about the
MARINE...Small Craft Advisory from 6 AM to 6 PM EST Saturday for ANZ153.
Small Craft Advisory from 1 AM to 6 PM EST Saturday for
Area Forecast Discussion
National Weather Service Houston/Galveston TX
858 PM CST Fri Jan 19 2018
Eight o`clock temperature observations are in the middle 50s
along the coast and across the northern tier of counties this
evening. The Houston metro observations were a touch cooler
ranging from 50-52 degrees, as they were seeing the occasional
break in cloud cover over the last few hours. Easterly winds will
continue to veer overnight, and onshore flow will prevail by
sunrise. The warm air advection pattern that is in place will
continue to allow both temperatures and dewpoints to rise through
the night as the coastal trough currently draped over Matagorda
Bay stretching southward into the Gulf of Mexico, shifts
eastward. Only minor changes made to the forecast in this update.
Increased cloud cover over the region tonight as cloud decks
continue to lower in height. Based off current observations and
the progression of this coastal trough, also went ahead and
increased dewpoints slightly and bumped up low temperatures
specifically across our northern tier of counties.
Patchy fog becoming areas of fog, is still expected to develop
beginning in western counties and fill in eastward through the
evening hours. Both the SREF and HRRR short term guidance are
indicating potentially dense fog developing in the early morning
hours between 06-08Z and continuing through the morning. The
threat for sea fog also creeps back into the nearshore waters,
Galveston Bay, and Matagorda Bay Saturday as ample moisture
return and warm air is advected over these cooler shelf waters.
.PREV DISCUSSION... /ISSUED 535 PM CST Fri Jan 19 2018/
AVIATION...[00Z TAF ISSUANCE]
Water vapor satellite imagery shows upper level trough over SE
Texas and this feature should be moving east tonight into
tomorrow. Warm air advection pattern will continue regardless as a
ridge builds over Texas in response to a deepening trough over
the Desert SW. This means a rather moist airmass will remain in
place supporting low ceilings/visibility. Tonight IFR and even
LIFR conditions are expected areawide with passing showers. This
continues tomorrow with possibly some improvement in ceilings to
MVFR by afternoon. Ceilings drop again Saturday evening back to
IFR. Visibility may be restricted to a mile or less in a few areas
in the morning. Showers may also cause a brief drop in
visibility. These conditions should continue into Sunday and not
improve until a front pushes through late Sunday night.
PREV DISCUSSION... /ISSUED 354 PM CST Fri Jan 19 2018/
Warmer conditions with periods of rain and fog are expected
through this weekend before a cold front arrives late Sunday.
Afternoon surface analysis shows a coastal trough stretching from
near Rockport to Victoria and south into the Gulf. East of this
feature, scattered to numerous showers aided by lift from an upper
low sliding across the region continue to build north and east
this afternoon. Expect this activity to translate east through the
evening and overnight hours as this upper low lifts towards the
lower Mississippi Valley with the coastal trough also lifting
inland and losing definition as this happens. Southerly flow will
spread across the region tonight in response, allowing low clouds
to fill in and patchy sea fog to develop along the coast. Inland
fog development will also be possible this evening and tonight,
especially as the coastal trough loses definition and weakens the
surface pressure gradient/low level winds. High resolution
guidance does indicate the potential for dense fog and will have
to monitor short term trends for any development overnight.
Periods of light showers will continue tonight through Sunday as
the region remains under an increasing warm air advection regime.
With shelf waters having cooled into the mid 40s to lower 50s, sea
fog will also be possible during this time across the marine areas
and along the coast as moisture deepens across the region. High
temperatures will warm into the lower 70s by Saturday and the mid
70s by Sunday as low level southerly flow strengthens as a lee
surface low ejects across the Central Plains. An associated
Pacific front or dryline developing across North Central/Central
Texas during the day Sunday may serve as a focus for thunderstorm
development Sunday afternoon and evening, but increasing southwest
flow aloft during this time may result in too much mid-level
stability for widespread thunderstorm development. A strong
thunderstorm cannot be ruled out along this boundary in the Brazos
Valley before a cold front overtakes it Sunday night, but the
aforementioned mid-level stability and the left front quadrant of
a 120+ knot upper level jet located over North Texas indicate this
potential may be farther north of the region.
Numerous to widespread showers and a thunderstorm or two will
develop along the cold front as it pushes southeast across the
region Sunday night, before clearing the coast Monday morning.
Surface high pressure and dry conditions build into the region
Monday through Wednesday with rain chances returning to the
coastal and marine areas by Thursday as deeper moisture pushes
back into the region.
Coastal troughing moving east and active area of shows and a few
thunderstorms will continue this evening as the trough shifts east
with the upper level s/w. Winds over the coastal water will increase
slightly the remainder of the afternoon with building seas. Will
continue the SCA for the 20-60nm waters and SCEC nearshore. Fog
threat increasing slightly tonight but better chances looks to be
with lighter winds and higher dewpoints over the cold shelf waters
Saturday afternoon/night. Persistent southerly flow with a 2-4 ft
swell Saturday and Sunday. Cold front sweeps through Sunday night
and winds gradually ramp up and will likely need SCA by Sunday
midnight onwards through Monday afternoon. Showers and possibly
thunderstorms with the FROPA. This should end any lingering fog
Band of lower CIGS from near ARM-HOU-EFD IFR/MVFR at 21z and this is
likely a good confirmation that ceilings will be dropping quickly
this evening as coastal trough slides eastward. Patchy fog
confidence is fairly high with lower VISBY probably in the CLL-CXO-
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 54 69 60 74 47 / 30 20 20 60 70
Houston (IAH) 51 71 60 75 54 / 30 30 20 40 70
Galveston (GLS) 55 66 59 69 56 / 50 30 20 20 60
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.
Small Craft Advisory until 6 AM CST Saturday for the following
zones: Waters from Freeport to the Matagorda Ship Channel
from 20 to 60 NM...Waters from High Island to Freeport from
20 to 60 NM.
AREA FORECAST DISCUSSION
National Weather Service New Orleans LA
357 PM CST Fri Jan 19 2018
The upper level trough that brought wintry precip and bitterly cold
temperatures continues to lift northeast. A piece of that trough was
pinched off and is located in Texas. Increasing 500mb heights from
the exiting trough and moisture/cloud increase from disturbance to
the west will result in significant rises in nighttime lows. Expect
a 15 degree jump in tomorrow lows and highs from today. At the same
time, scattered showers will be possible as this week upper
trough/low drifts east across the northern gulf coast. HRRR precip
output shows light showers pushing into forecast zones along the
Atchafalaya basin overnight. Therefore, have introduced slight
chance pops west of a BTR to HUM line. Moving into Saturday,
guidance is slightly higher than previous solutions but still quite
a bit lower than older runs. Decided to bump up rain chances for
areas west of I-55 but kept them at a halfway point between previous
forecast of 20% and MAV/MET 40%. Additionally, sea fog will likely
become an issue along coastal parishes of LA beginning late tonight
as dewpoints rise into the mid 50s. Attm, it appears this will
mainly be limited to areas west of the Mississippi River. Ridge will
then build in Sunday which will stunt rain and allow continued
warming. You may think summertime has come early on Sunday compared
to last week when temperatures rise into the low 70s.
The CWA may be looking at a few thunderstorms at the start of next
week. Models show an upper trough tracking west across the southwest
US Saturday and Sunday. A low will develop at the base of the trough
and race northeast towards the Great Lakes Monday. This weather
pattern typically brings a relatively thin line of showers with
embedded thunderstorms through. Intensity shouldn`t be of much
concern as instability and dynamics will not be very conducive for
vigorous development. Temperatures will likely drop back down behind
the front mid week, but only on the order of 10ish degrees with a
quick rebound by the end of the week.
Weak upper level wave over east Texas will spread moisture amd
ceilings over most terminals from west to east through this evening.
Most will be around OVC080 but will lower to OVC050 this afternoon
for KBTR and KHUM. These ceilings should remain rather stable at
OVC050-060 through tonight. All terminals will show some possibility
towards observing either -DZ or -RA by Saturday morning. At this
time, rain chances remain slight. Therefore, will hold off adding
precip to latter part of the forecast. 18
High pressure will shift east through tonight bringing return flow
back to the northern gulf tonight into Saturday along with some
rain. Foggy conditions near the coast could develop Saturday night
through Sunday morning and Sunday night ahead of the next cold front
which will move through Monday. A stretch of strong northerly winds
look to occur again behind this front through next Wednesday. A
trough will develop over the gulf by mid week. This feature will
prolong an easterly flow over the coastal waters from Wednesday
through next weekend. 18
DSS code: Green.
Decision Support Services (DSS) Code Legend
Green = No weather impacts that require action.
Blue = Long-fused watch, warning, or advisory in effect or
high visibility event.
Yellow = Heightened impacts with short-fused watch, warning or
advisory issuances; radar support.
Orange = High Impacts; Slight to Moderate risk severe; nearby
tropical events; HazMat or other large episodes.
Red = Full engagement for Moderate risk of severe and/or
direct tropical threats; Events of National Significance.
.PRELIMINARY POINT TEMPS/POPS...
MCB 40 64 51 71 / 10 20 0 10
BTR 41 66 54 72 / 10 30 10 10
ASD 41 65 52 70 / 10 20 0 10
MSY 46 66 55 70 / 10 20 0 10
GPT 40 63 50 66 / 10 20 0 10
PQL 36 65 48 67 / 10 10 0 10
Area Forecast Discussion
National Weather Service Morristown TN
933 PM EST Fri Jan 19 2018
Isentropic lift leading to widespread low-level clouds to our
southwest on the western periphery of a low-level ridge. Have
increased cloud cover in the forecast to be closer in line with
current observations and trends. Believe that the current RAP does
a good job at initializing current cloud cover and showing it
moving into our forecast area tonight and Saturday. With
925-850mb clockwise winds around the low-level ridge and the ridge
axis extending through our forecast area, believe WNW winds and
upslope flow conditions will be probable for the mountains late
tonight and Saturday with a slight chance of some drizzle across
the higher terrain because of the orographic lift. May even have
some patchy freezing drizzle late tonight across the higher
terrain as lift increases near sunrise. With cloud cover expected
to arrive across NETN/SWVA/SWNC latest tonight, expect these
areas to be the coldest tonight with efficient radiational cooling
until the cloud cover increases late. If cloud cover does stick
around during the day on Saturday as the RAP and NAM indicate, max
temperatures may be several degrees below MAV MOS guidance.
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 30 54 37 64 / 0 0 10 0
Knoxville McGhee Tyson Airport, TN 29 51 38 59 / 0 10 10 10
Oak Ridge, TN 29 50 38 58 / 0 10 10 10
Tri Cities Airport, TN 22 49 36 57 / 10 10 10 10
Area Forecast Discussion
National Weather Service San Francisco Bay Area
342 PM PST Fri Jan 19 2018
.SYNOPSIS...Cool conditions and scattered showers will continue
through late tonight. Drier weather returns on Saturday. A band
of rain, possibly heavy at times, moves into the North Bay Sunday
evening spreading southeastward Sunday night into Monday morning.
Rain returns during the middle of next week with showery weather
lingering into late next week.
.DISCUSSION...as of 1:45 PM PST Friday...Near term conditions
have not changed much from this morning. Cool and unstable airmass
still resides over the Bay Area. As a result, instability showers
continue across the region. Have not see any recent lightning,
but given the convective nature and colder airmass these showers
may be heavy at times and contain small hail. A few spotters have
confirmed small hail close to pea size hail. Current temps of some
of the higher peaks are hovering right around 32 degrees.
Therefore, any passing shower could drop some snow on the highest
peaks. Latest HRRR and local WRF models keep instability showers
through late tonight and current forecast will reflect this.
Brief ridging develops over the Bay Area on Saturday with no
precip expected. Despite drier conditions temperatures will still
remain cool with highs mostly in the 50s and higher peaks in the
40s...about 5 degrees below normal.
The ridging quickly diminishes on Sunday as the next system takes
aim at the Bay Area. Latest model timing brings a weakening
Atmospheric River into the North Bay between 12-18Z and then
gradually spreading southward through the day. There could be a
brief period during Sunday afternoon/evening where moderate to
heavy rain may develop over the North Bay. Of greatest concern
would be intense rain in short period of time impacting the burn
scars. As of now it doesn`t appear to be a major concern, but
something to monitor as Sunday gets closer. Rain chances will
continue well into Monday with scattered showers remaining. Storm
total rainfall from Sunday into Monday will be greatest over the
North Bay 0.75-1.25"...SF/Santa Cruz Mts 0.25-0.75"...less than
A brief respite is possible late Monday into early Tuesday, but
another system will bring additional rain to the region. It
appears the storm door remains open with a decent cold front and
more rain moving through Wednesday into Thursday. Cool and chilly
weather will continue through Friday.
.AVIATION...as of 3:42 PM PST Friday for 00Z Saturday TAFs. VFR
conditions are expected to prevail at most terminals through the
period. The usual exception will remain KSTS where locally dense
morning fog is forecast. Visible satellite imagery from GOES-East
reveals scattered cumulus clouds distributed throughout the
district. Expect the cumulus coverage to decrease heading toward
and beyond sunset with the loss of daytime heating. Additionally,
can`t rule out a stray shower or brief heavy downpour at the
terminals over the next 3 to 6 hours. Will continue to monitor
and amend as necessary.
Vicinity of KSFO...VFR conditions are expected to prevail. FEW/SCT
cumulus clouds around 3-5k ft AGL will continue to
intermittently pass over the terminal through sunset, which may
produce a locally brief shower. Will continue to monitor and amend
as necessary. West winds 10 to 15 kt this afternoon will gradually
diminish through the evening.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR conditions are expected to prevail
for much of the period with FEW/SCT cumulus clouds through sunset.
KMRY could see some overnight SCT clouds below 3,000 ft AGL that
could potentially bring tempo IFR conditions to the terminal, but
confidence is too low to include in the TAF. Will continue to
monitor and amend as necessary.
.MARINE...as of 03:28 PM PST Friday...Swells are slowly beginning
to decrease across the coastal waters and will continue to do so
over the weekend. However, moderate swells and increasing winds
will still create hazardous conditions. Scattered showers
continue to move over the waters. No lightning has been observed
thus far over the forecast area, but a slight chance of
thunderstorms still exists through this afternoon. Some cells may
contain small hail. Winds will turn southerly and increase on
Sunday morning ahead of the next system.
.Tngt...High Surf Warning...CAZ006-505-509-529-530
SCA...Pt Reyes to Pigeon Pt 0-10 nm
SCA...Pigeon Pt to Pt Pinos 0-10 nm
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Rough Bar Advisory for SF Bar
PUBLIC FORECAST: MM
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Area Forecast Discussion
National Weather Service Charleston WV
716 PM EST Fri Jan 19 2018
With high pressure passing south of the area, a southwest flow
will bring milder air through the weekend, with a warm front
passing Saturday. A strong cold front crosses late Monday.
.NEAR TERM /THROUGH SATURDAY/...
As of 705 PM Friday...
Watching the stratus deck in the Tennessee Valley this evening
and the implications here overnight. The NAM and RAP models seem
to have a good handle on this in their respective soundings.
They bring this deck into parts of the area late through
significant moistening in the H9 to H875 layer, primarily along
and east of the Ohio River. As a result, I have increased sky
grids considerably late and carried this deck through much of
Saturday east of the Ohio River. Tweaked hourly temps tonight to
show a quick fall in the hollers and sheltered valleys versus
the hilltops. Once the clouds move in, temps should level off
and rise toward morning.
As of 200 PM Friday...
A ridge of high pressure remains in place with the center of
high pressure over the north central Gulf coast providing dry
weather to start the near-term. Brilliant sunshine and modest
low- level warm air advection warms us nicely into the 40`s
across lowland locations this afternoon. Decoupling tonight a
little tougher than last night with SW flow picking up aloft,
but still a decent bet in the most deeply incised, sheltered
valleys. Models are still struggling to latch onto any one
solution at this point. So have chose a middle-of-the-road
approach favoring cooler temperatures in low spots.
Tomorrow, moisture starts streaming in from the west/southwest
providing some low-level clouds/stratus to start. Low-levels and
eventually mid-levels saturate through the day, particularly
across the northern zones. So, have decided to introduce drizzle
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 230 PM Friday...
A warm front moves towards the area late Saturday night with
overrunning. Forecast soundings are indicating a period of
possible drizzle and fog as the warm moist air starts to push
in. In the Northeast mountain valleys, some areas could be
below freezing and may have a period of freezing drizzle or fog
before we eventually warm early Sunday morning. Warm frontal
light rain will continue on Sunday, with very light amounts
expected. Temperatures Sunday will just up into the mid to
possibly upper 50s.
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 245 PM Thursday...
Strong cold front will push into the Ohio Valley Monday
afternoon. POPs increase quickly after 18Z Monday and widespread
rain will overspreads the region Monday night. Thinking amounts
should only be a half in or less in most places, but on the high
end, maybe three quarters of an inch could fall in some spots.
Cold air will push in behind the front on Tuesday and could see
a changeover to snow, especially in the mountains, but moisture
will be limited. Flow aloft settles back into a zonal pattern
for the back end of the extended forecast. High pressure and
warmer air should work back in by the end of next week.
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 710 PM Friday...
VFR conditions thru 06Z amid light southwesterly surface winds.
Thereafter, low level moisture will increase with low stratus
building into the area from the Tennessee Valley. This should
allow MVFR cigs to develop across most terminals, except KPKB,
in the 09 to 12z time frame. This stratus will linger through
much of Saturday and perhaps lower during the afternoon,
especially at KBKW.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SUNDAY...
FORECAST CONFIDENCE: High.
ALTERNATE SCENARIOS: Timing onset of MVFR cigs may vary an hour
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11
EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06
CRW CONSISTENCY H H H H H H H H H M M L
HTS CONSISTENCY H H H H H H M M M M L L
BKW CONSISTENCY H H H H H H H H H M M L
EKN CONSISTENCY H H H H H H H H H H M L
PKB CONSISTENCY H H H H H H H H H M M L
CKB CONSISTENCY H H H H H H H H H H H L
AFTER 00Z SUNDAY...
IFR possible Saturday night with fog and drizzle...and again
Monday/Monday night with rain.