Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/12/17
Area Forecast Discussion
National Weather Service Gaylord MI
1148 PM EDT Wed Oct 11 2017
.UPDATE...
Issued at 957 PM EDT Wed Oct 11 2017
Surface ridging in control of our weather tonight, bringing
clear skies to much of the area. However, still a band of lower
clouds rotating west along and south of the M-55 corridor. Some
clearing noted back across Lake Huron, and would expect to see
some of this cloud deck erode in the coming hours. Any clearing
will be short-lived, as slowly veering winds bring an extensive
area of low clouds to our south back north very late tonight, and
especially on Thursday. Latest guidance trends much more
aggressive swinging these low clouds north, and fully expect much
of the area to be completely cloudy by later Thursday. Have
trended the forecast to this more aggressive scenario, and as
such, have lowered highs a few degrees Thursday.
&&
.NEAR TERM...(Tonight through Thursday)
Issued at 255 PM EDT Wed Oct 11 2017
...Remaining showers ending late afternoon/early evening...
High Impact Weather Potential...None.
Pattern Synopsis/Forecast...Surface low continue to make its way
thru Ohio this afternoon...while strong high pressure is center
along the Ontario/Quebec border. Northern edge of the large swath of
rain that developed north of the surface low center is slowly
exiting out of our SE CWA as the low pushes toward the Atlantic
coast. Clouds are steadily diminishing across our NW CWA as even the
upper level moisture/cloud cover begins to depart on the backside of
this system. Temps have struggled to warm out of the 50s so far
today due to thick clouds and precip.
Both the NAM and the RAP pull the last vestiges of shower activity
out of our far SE CWA just before 00Z this evening...with clouds
quickly diminishing behind the back line of precip as drier air thru
the column filters into the region. Gradient remains sufficiently
tight for dry easterly low level flow to help preclude fog
development tonight. Thus...expect mainly clear skies for our entire
CWA for late evening and overnight. Low temps will cool mainly into
the low to mid 40s.
Thursday will begin with mainly clear skies for much of our CWA
before some low cloudiness begins to push back northward into our
CWA as low level flow shift to the SE ahead of our next approaching
system. Cannot rule out a slight chance of a shower across our SE
CWA as well in the afternoon. High temps will warm into the low to
mid 60s across our entire CWA.
&&
.SHORT TERM...(Thursday night through Sunday)
Issued at 255 PM EDT Wed Oct 11 2017
...Periods of unsettled weather through this weekend...
High Impact Weather Potential: Periods of soaking rain Friday night
and again Saturday night-Sunday. Rain may fall heavily at times
Saturday evening into early Sunday along with increasingly gusty
winds. Can`t rule out a few rumbles of thunder Sunday and
depending on the timing, strength and placement of the
system...perhaps the potential for a few severe storms.
Pattern Forecast: Quite the active pattern setting up across the
central U.S. late this week through the upcoming weekend. Despite
light/scattered shower activity possible Thursday night into early
Friday, focus revolves around the Friday evening through Sunday
timeframe. Low pressure rapidly trekking across northern
Manitoba/Ontario Thursday night into Friday is expected to drag an
elongated cold front across northern Michigan Friday night. This
boundary will become stationary across Lower Michigan during the day
Saturday providing the focus for a stronger mid level wave and
associated deepening surface low to track along as it emerges from
the Intermountain West/Plains. Still plenty of uncertainty exists
this weekend with respect to low pressure strength, timing and
track. However, the potential is becoming likely for periods of rain
across much of northern Michigan...potentially heavy at times.
Primary Forecast Concerns/Challenges: Gauging precip potential
throughout the forecast period with precedence put on the Friday
night through Sunday timeframe.
Increasing clouds from south to north Thursday afternoon will
continue right into Thursday night with perhaps a few showers
developing as a result of lingering low-mid level moisture and a
weak northeastward moving boundary. This activity is expected to
curtail by Friday morning; however, additional rain chances arrive
from the northwest Friday evening.
Aforementioned elongated cold front is expected to gradually cross
northern Michigan Friday night with showers becoming likely over
eastern Upper and northwest Lower Friday evening...gradually
transitioning along and east of I-75 overnight. Wouldn`t be shocked
to see showers continue for some early Saturday; however, a lack of
guidance consistency with respect to the placement of the stalling
cold front yields decreased confidence to overall precip coverage
during the daylight hours Saturday.
The stalled boundary across central/southern Lower Michigan
gradually begins to lift northward as a warm front Saturday
afternoon as low pressure deepens across the Mississippi Valley and
progresses northeastward into the western Great Lakes. Rain is
expected to become likely once again Saturday evening continuing
into Sunday...potentially falling heavy at times as PWATs rise to
nearly 1.50 inches (+1 to +3 standard deviations for mid-October).
GEFS ensemble means suggest upwards of 1.00-2.00 inches of QPF
through the Saturday evening-Sunday time frame across northern
Lower...slightly less in eastern Upper. Again, low confidence
prevails in terms of the small scale details at this juncture, but
there`s at least a small threat for a few rumbles of thunder just
given the degree of moisture and dynamics with this system. Given
the progged 150+ kt jet structure aloft and the amount of effective
bulk shear (in excess of 60 kts) late Saturday night-Sunday morning,
a conditional severe weather threat can`t be ruled out either
(despite very limited instability)... although the better threat of
that may remain downstate and into the Ohio Valley.
Precip chances gradually diminish Sunday, although increasingly
gusty winds and cooler temperatures ushered in on the back side of
the departing low may prove to be enough to start lake processes
with scattered lake effect rain showers continuing across the
typical NW flow lake effect zones of northwest Lower and eastern
Upper. Trends continue to suggest the brief cold spell should be
just warm enough (but maybe not by much) to prevent any
snowflakes from mixing in across the higher terrain.
.LONG TERM...(Sunday night through Wednesday)
Issued at 255 PM EDT Wed Oct 11 2017
High impact weather potential: Minimal.
Cold air behind Sunday`s departing system is rather fleeting as
heights aloft begin to rise during the day Monday. Any lingering
light/scattered lake effect rain activity is expected to come to an
end during the day Monday. Another system early next week is
expected to pass by just to our north; however, high pressure over
the midsection of the CONUS should provide mainly dry conditions
locally with gradually moderating temperatures.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1142 PM EDT Wed Oct 11 2017
Mostly clear skies through much of the overnight across most of
the area. Extensive area of mvfr/ifr cigs just clipping Manistee,
but is expected to scatter out early this morning. Additional
mvfr/ifr producing overcast will sweep north across all taf
locations by later today, with low cigs and areas of drizzle
expected this evening. Light east winds will turn southeast with
time.
&&
.MARINE...
Issued at 255 PM EDT Wed Oct 11 2017
Winds and waves will continue to reach SCA criteria across our Lake
Huron nearshore areas tonight and Thursday thanks to persistent
easterly onshore flow north of low pressure tracking north of the
Ohio Valley. Remaining rain near Saginaw Bay will diminish late this
afternoon and come to an end...with dry wx expected for the rest of
tonight and Thursday morning. Additional chances of showers will
develop Thursday afternoon and night for much of our nearshore
areas.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 6 PM EDT Thursday for LHZ345>349.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...MB
NEAR TERM...MR
SHORT TERM...MG
LONG TERM...MG
AVIATION...MB
MARINE...MR
Area Forecast Discussion
National Weather Service Des Moines IA
620 PM CDT Wed Oct 11 2017
.SHORT TERM.../Tonight through Thursday/
Issued at 325 PM CDT Wed Oct 11 2017
The main forecast concern was focused on stratus deck lingering
into tomorrow and with the drizzle/fog potential early Thursday
morning. Leaned toward the latest runs of the RAP, HRRR and ESRL
HRRR for cloud cover location as they have a good handle on the
current trends across the state.
Strong inversion develops this evening and looks to trap the low
level moisture/stratus deck into the morning Thursday, particularly
across the eastern half of the CWA where the stratus currently
resides. Confident that the eastern portions of the CWA will remain
under the low stratus through at least 12z Thursday, with it
lingering and trying to dissipate b/t 12-15z when the WAA begins to
develop. The real tricky part is the central sections of the
forecast area, from north to south from around Lamoni through Des
Moines northward through Ames to Kossuth County. This is currently
the western edge of the stratus and the question remains if and how
far the stratus retrogrades back west-northwest this evening. In
this location, have patchy fog mentioned as a few the hires models
keep the stratus as is or erodes it slightly eastward allowing for
radiational cooling to setup and thus fog to develop. Concerned that
the western third of the CWA will see fog develop overnight with the
radiational cooling setup in this location. Dew point depressions do
become less than 5F to even 0F by around 09z Thursday and the latest
runs of the HRRR/RAP and even the ARW/NMM suggest fog developing by
around 09z. Timing of the WAA the west prior to 12z Thursday will
determine if this will hold off the radiational fog to development.
Across the east, there is very weak lift in the saturated column per
MCW to ALO soundings and kept mention of drizzle overnight. Low
confidence with any measurable precipitation at this time and
currently left out any pops.
.LONG TERM.../Thursday night through Wednesday/
Issued at 325 PM CDT Wed Oct 11 2017
A cold front will enter northwest Iowa Thursday night then will
continue to move slowly southeast on Friday. The initial airmass
will begin dry as the boundary arrives though mid-level moisture
advection will arrive during the day on Friday which will help
enhance precipitation chances over mainly the northern Iowa.
Precipitation chances would settle south Friday night as the
boundary moves into northern Missouri. Moisture depths though
would support light rain or even drizzle in some areas.
A strong short wave will move into the Nevada/Utah region Friday
night and move east into the Western Plains on Saturday. This
will create increasing southwest flow aloft and will help lift the
surface boundary back north. In addition, this flow will bring
strong low and mid-level moisture advection to the southeast half
of Iowa. PWAT values will increase to near 1.75 inches by Saturday
afternoon or near 250% of normal. Warm cloud depths will be near
12.5 kft and the setup is good for an efficient rain producing
system. The southeast portion of the forecast area is currently
outlooked for severe weather by SPC on Day 4. As of now, the
threat for severe weather looks conditional on if the clouds can
break and temperatures do recover. Any severe weather threat
should be relegated to the far southeast including the Ottumwa and
Bloomfield areas.
The precipitation will quickly end Saturday night. The wind will
increase behind the boundary as cold advection arrives and the
pressure gradient increases as low pressure intensifies to the
north. Wind gusts over 35 mph are possible and may reach wind
advisory criteria for a brief period. High pressure will arrive
during the day Sunday and will diminish the wind gusts by the
afternoon. Currently have low temperatures in the upper 30s for
Sunday night. May not be low enough at this point and could have
frost potential by Monday morning. Current forecast low dew points
are in the lower 30s over northwest Iowa and lows may approach the
dew point values. Generally dry and warmer conditions Monday and
Tuesday as high pressure moves southeast and southerly winds
return.
&&
.AVIATION.../For the 00Z TAFS through 00Z Thursday evening/
Issued at 620 PM CDT Wed Oct 11 2017
MVFR/IFR conditions over the east may expand back to the west
overnight. This will need to be monitored. If the stratus does not
move back in, then some patchy fog may develop and bring local MVFR
visibilities to areas mainly west of I-35.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Podrazik
LONG TERM...Donavon
AVIATION...FAB
Area Forecast Discussion
National Weather Service Quad Cities IA IL
242 PM CDT Wed Oct 11 2017
.SYNOPSIS...
Issued at 240 PM CDT Wed Oct 11 2017
Storm system that brought widespread soaking rain to much of the
cwa yesterday was in the Ohio Valley region. Cyclonic flow as far
west as central IA/eastern MN, combined with the moist ground, has
kept low stratus in place all day. As a result, temperatures were
on the cool side with afternoon readings only in the 50s to around 60.
&&
.SHORT TERM...(This Evening through Thursday)
ISSUED AT 240 PM CDT Wed Oct 11 2017
Forecast focus on clouds and possible drizzle.
Tonight: Weak surface ridge comes across the cwa providing very
light winds. This will be tough to scour out the clouds considering
forecast soundings indicate a strenghthening inversion at 850 mb.
This will keep the low level moisture from the recent rainfall
trapped below the inversion. Therefore, the widespread low stratus
is expected to remain in place. Also, soundings indicate a classic
drizzle scenario with very dry air above the inversion, and weak
omega in the stratus layer, which the HRRR picks up on. For now
will keep the mention of patchy drizzle and patchy fog in the grids.
Later shifts can monitor for the possibility of more widespread
drizzle if the forcing is a bit stronger in the sub-inversion layer.
Due to the low stratus, there won`t be much of a diurnal spread
in temperatures, with lows in the lower 50s.
Thursday: Low stratus to remain in place for much of the morning,
then skies should clear from west to east during the afternoon.
High pressure ridge will shift to our east with warm air advection
kicking in (southerly winds), which should allow for the stratus
to gradually erode. Maximum temperatures will push into the 60s,
which is normal for mid October.
.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 240 PM CDT Wed Oct 11 2017
Main forecast concern for the long term forecast are the chances for
thunderstorms this weekend and with it the chance for heavy rain and
severe weather. After this front this weekend, the rest of the long
term looks dry and more seasonal as far as sensible weather goes.
Friday...the return of warmer temperatures and boundary layer
moisture is expected as the mean flow turns southwest. H85 flow
will advect in warmer more moist air. H85 convergence is expected
to be just north of the CWA as a weak wave ripples through the flow.
This will be enough to initiate showers and some thunderstorms across
the northern CWA Friday evening. As this convection continues
through the overnight, the effective warm front will be pushed south
into our CWA. Rain from Friday night across the area, may set the
stage for hydro concerns on Saturday. Friday night, instability
will be low, however deep layer shear is conducive for midlevel
storm rotation. Any midlevel rotation would lead to increased
rainfall across the area along with possibly the isolated elevated
hail storm. The threat for severe weather is low on Friday evening.
Saturday, major questions remain as to where the effective warm
front is. A strong short wave is expected to approach the area
later in the day into the evening. At the same time a low is
expected to move across the boundary. Short of a negatively tilted
trof, wherever the warm front is Saturday morning is probably where
it will stay. Shear is quite strong along this boundary and would
lend itself well to low level storm rotation. Any storm near this
boundary will likely have a threat to become severe. The next
question is whether or not we will have a lull in the precip and
cloud cover on Saturday. If we dont have a lull, convection will
likely increase with the sfc low. If there is a lull, the threat
for severe weather will increase.
Another concern is the stalled boundary with PWATs near 2 inches.
Near continuous H85 flow will feed convection plenty of moisture.
Areas near and north of the warm front could see heavy rain on
Saturday. With the rain we had yesterday along with the forecast
rain for Friday, hydro issues could become an issue with possible
rises on area rivers along with potential flash flooding.
There are a lot of possibilities with the forecast for this weekend.
Regardless, now is the time to start paying attention to this
forecast. Additional model runs will lead to more confidence in a
forecast solution.
Past Saturday, cooler and drier air is expected without a good
chance of precip through mid next week.
&&
.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
ISSUED AT 148 PM CDT Wed Oct 11 2017
IFR/low MVFR cigs this afternoon then IFR/ocnl LIFR cigs/vis
tonight into Thursday morning. North to northeast winds less than
10 knots through tonight, then becoming south on Thursday.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...Haase
SHORT TERM...Haase
LONG TERM...Gibbs
AVIATION...Haase
Area Forecast Discussion
National Weather Service Houston/Galveston TX
857 PM CDT Wed Oct 11 2017
.DISCUSSION...
Surface analysis has high pressure over the Ozarks NE towards the
Great Lakes. Ridge axis then extends back to the SW into Texas
supporting light northeast winds over SE Texas. Favorable
radiational cooling conditions should allow for temperatures to
fall into the low 60s for most of the area with a few spots of
upper 50s. Low temperatures in the 60s/70s will be confined to the
coast. Temperatures increase to summer time levels over the
weekend with a cold front late Sunday/Monday to bring back fall
conditions. Overall forecast looks on track and only adjustments
were for ongoing temperature/dewpoint trends.
Overpeck
&&
.PREV DISCUSSION... /ISSUED 629 PM CDT Wed Oct 11 2017/
AVIATION...
Dry air and northeasterly flow will keep us in VFR throughout the
period. Winds will slowly gradually veer and become easterly or
even a bit south of easterly by the end of the period. However,
the pressure gradient will be loose and winds will be light,
mitigating impacts of the wind shift. Indeed, the gradient may be
so loose that winds will be fairly light and variable,
particularly overnight.
Luchs
PREV DISCUSSION... /ISSUED 352 PM CDT Wed Oct 11 2017/
DISCUSSION...
Other than a few clouds over the southern counties, skies are
clear with temperatures in the upper 70s to low 80s. Skies will
remain mostly clear tonight with dew points in the 50s and calm
winds, bringing low temps tonight down into the low to mid 60s.
Onshore flow returns tomorrow, bringing dew points back into the
60s and warming temperatures into the mid-80s. Models agree that
the upper level ridge which began to build into the area last
night will remain centered over the Lower Miss Valley. This will
drive the higher moisture and greater precipitation chances
further south into the Texas/Mexico border through Saturday,
leaving us mostly dry through the rest of the week except for a
few offshore showers. The biggest rain chance over the next few
days will be associated with the seabreeze during the day
Saturday and Sunday as southwesterly winds bring higher moisture
along the coast.
The next big weather change will come with the passage of the next
cold front. Timing of the frontal passage seems to have slowed
down with both the 12Z GFS and Euro indicating passage closer to
12Z on Monday with higher chances of rain on Sunday night ahead
of the front. In its wake will be cooler and drier air with dew
points from the low 60s near the coast to the upper 40s farther
inland and temperatures in the upper 70s to low 80s for the
remainder of the week.
22
MARINE...
Winds have continued to weaken as high pressure slides in from the
NW, and the pressure gradient over the region slackens behind the
cold front that moved through SE TX earlier this week. Seas are
still ranging between 2 to 4 feet but are expected to continue
lowering to 1 to 3 feet by Thursday. Early Thursday morning, could
see some isolated shower development in the western waters. Short
term guidance such as the HRRR and RAP13 show this development
beginning around 06-09Z, and then moving these showers towards
coast but dissipate before making their way on land.
Onshore flow should return to the forecast late work week, bringing
with it an increase in moisture. Next real feature that will impact
the marine zones will be the next wind shift behind the cold front
expected to impact SE TX late Sunday into Monday. Wind speeds should
once again increase behind the front and become more northerly,
along with seas also rising between 3 to 5 feet late Monday into
Tuesday.
Hathaway
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 62 87 67 90 69 / 10 10 10 10 10
Houston (IAH) 64 87 68 90 70 / 10 10 10 10 10
Galveston (GLS) 73 84 77 87 77 / 10 10 10 10 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
Discussion...39
Area Forecast Discussion
National Weather Service Wilmington NC
923 PM EDT Wed Oct 11 2017
.SYNOPSIS...
Unseasonably warm and humid weather will continue through
Thursday. A weak cold front will reach the Carolinas late
Thursday, with relatively drier and slightly cooler weather
heading into the weekend, but continuing unseasonably warm.
Fall-like weather should arrive next week as a stronger cold
front moves through.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 930 PM Wednesday...Temperatures are dropping almost
exactly in line with prior forecast rates. I have made some
minor decreases in forecast cloud cover overnight based on
current satellite imagery, but not enough to significantly
alter the forecast. Discussion from 730 PM follows...
500 mb high pressure centered along the Gulf Coast and surface
high pressure centered just offshore continue to provide late
summer-like weather across the Carolinas. 850 mb temps near +18C
are above the 95th percentile for this time of the year, as are
precipitable water values around 2.20 inches. Low-level winds
will become quite light overnight, but should still not allow
good enough radiational cooling to keep from setting more record
warm low temperatures for the date.
Forecast and record warm lows for late tonight, October 12:
Wilmington: forecast 73, record warm low temp 73 in 1990.
Florence: forecast 72, record warm low temp 70 in 1983.
N. Myrtle Beach: forecast 73, record warm low temp 68 in 2010,
but records only began in 1999.
Lumberton: forecast 72, record warm low temp 65 in 2011,
but records only began in 1999.
A modest subsidence inversion around 6000-8000 feet aloft is
helping today`s cumulus clouds persist as altocumulus this
evening. Some of these clouds will persist overnight, and will
be joined by low stratus and areas of fog late, especially
inland. A very weak upper disturbance over east Tennessee and
the NC mountains will drift down into the Sandhills region late
tonight, and the latest RUC shows late-night showers developing
with this feature. I`ll leave the late night 20 PoP in for this
feature in the Lumberton vicinity as forecast soundings do show
elevated instability persisting overnight when layers from
2000-5000 feet are considered.
Low temps are forecast to reach 72-74 for most areas, little
changed from the previous forecast.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 230 PM Wednesday...Weak backdoor type cold front will
drop south through the area late Thurs. Looks like this will
remain the focal point for some shwrs/iso thunderstorms into
early Thurs evening. With the loss of heating and lack of any
real upper level support, expect activity to diminish through
Thurs late eve leaving a very moist low level column up through
the first few thousand ft.
Northeast to easterly flow behind weak cold front leaves a
continuous flow of low level moisture off of the Atlantic into
Fri. The winds should kick up behind the front slightly which
should lead to the development of low stratus toward daybreak on
Fri which should lift through the aftn leaving a layer of
strato cu across the area Friday aftn. The limited sunshine and
slight modification of the air mass will produce temps closer to
the lower end of 80s...a good 5 degrees above normal for most
places.
Pcp water values should drop closer to 1.5 inches or below on
Fri behind the front, mainly west of I-95 corridor and north of
local area. The boundary may linger just south of area with
convection possible Fri aftn in slightly more moist and unstable
air mass over SC or mainly NE SC coastal areas.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 230 PM Wednesday...Temperatures will be well above normal
through the weekend into early next week with H5 ridge across
the Southeast United States. The ridge is shown to break down
early next week which could open the door to a cold frontal
passage and a much cooler airmass for Tuesday and Wednesday.
However, the H5 pattern becomes less amplified by early next
week creating some doubt that the front will move through late
Mon/Tue as currently advertised by the GFS. A slower
progression of the front would carry rainfall chances into
Tuesday as well. Followed a blend of MEX/ECE max and min
temperatures Sat-Monday but leaned toward the warmer MEX temps
Tue-Wed time frame.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
As of 00Z...VFR conditions should persist through 05Z before
some fog begins to develop inland. Rich moisture and light winds
overnight will favor the development of low stratus and fog
inland, with a lesser potential down at the coast. Our latest
forecast brings IFR conditions into the FLO/LBT airports by 09Z,
but the potential for IFR is currently too low to include at the
ILM, CRE, or MYR airports. Conditions should improve to VFR
across the area between 13-15Z Thursday with another round of
scattered showers and t-storms developing again during the day.
Extended Outlook...MVFR/IFR conditions are possible during the
mornings Friday and Saturday from ceilings and/or reduced vsby
from fog. Scattered showers are expected each day which could
produce brief MVFR/IFR conditions.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 930 PM Wednesday...High pressure off the coast will
maintain a light southerly wind and dry weather overnight. Seas
currently 2-3 feet are primarily due to an 8-second southeast
swell. Models are in excellent agreement and no weather
surprises should occur tonight.
SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 230 PM Wednesday...A weak cold front will drop south
across the waters late Thursday into early Friday. SW winds will
shift NE overnight Thursday with a slight brief increase behind
the front through Friday, but overall not expecting winds
greater than 10 kts . Seas will continue to run right around 3
ft through the period.
LONG TERM /SATURDAY THROUGH MONDAY/...
As of 230 PM Wednesday...Weak high pressure will prevail at the
onset of the long term period. The high will shift offshore
allowing winds to veer from a northeasterly direction Saturday to
a southerly direction during Sunday. A cold front is expected to
approach the waters during Monday but the GFS may be too fast
translating into a longer period of southerly winds. Seas are
expected to average 3 ft or less through the period
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...
NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...SRP
AVIATION...TRA
Area Forecast Discussion
National Weather Service Elko NV
241 PM PDT Wed Oct 11 2017
.SYNOPSIS...Dry conditions will continue through Thursday however
there may be some smoke from the California fires blowing our way,
reducing visibility at times across the northern part of the state.
A storm system will bring a chance for rain and snow showers to
northern Nevada Friday through early Saturday.
&&
.SHORT TERM...Clouds are increasing across the Pacific Northwest
ahead of a low pressure system approaching the coastline. Its been
a rather mild day today with relatively light winds...some
occasional gusts in the 20s. A band of high cloudiness is
quelling temperatures for now but max temperatures still reached
into the 60s across the board, northern and central Nevada. In the
short term, there will be a low pressure system dipping into the
Great Basin, bringing some shower activity mainly to northern
Nevada, and a brief cold snap.
Tonight through Thursday night. Dry weather will continue.
Presently smoke from the California fire situation is making its
way into the Winnemucca area, reducing visibility at the
Winnemucca airport. Its possible it will decrease visibility all
along Interstate 80 tonight as the southwest flow aloft increases
ahead of the incoming low pressure system. High temperatures will
generally make it into the 50s. Low temperatures will be in the
20s.
Friday through Saturday morning. Low pressure will provide at
least a glancing blow to northern Nevada and it will likely be a
quick hitter. At this juncture, precipitation chances will be
highest across northern Nevada, noting that there is potential for
more spread further south with the identification of two upper
low circulations within the mean trough over Idaho and Montana.
Snow levels will be dipping to near 6000 feet so Interstate 80 in
the Pequops will get dusted with snow as the front moves through.
High temperatures will generally make it into the 50s. Low
temperatures will be in the 20s.
Saturday afternoon. Dry conditions reappear. Models indicate a
clean exit of the trough, moving it as far as Colorado and Wyoming
by late afternoon. Then the cold air will begin to move into the
CWFA. High temperatures will be in the 40s.
.LONG TERM...Saturday night through Wednesday. Sunday morning will
be quite chilly across the area with many locations in the teens
and lower/middle 20s. After that, a slight warming trend will
commence with highs rising back into the 60s/70s for
northern/central NV. There are hints of the middle to end of next
week becoming active, but confidence is low at this time. More of
something to keep in the back of your mind if making plans to
travel or enjoy the outdoors.
&&
.AVIATION...VFR expected next 24hrs for KTPH/KELY. Smoke is quite
dense this aftn ahead of a weak frontal bndry. This will continue
for KWMC at least until early evening with IFR/MVFR conditions.
KEKO should see smoke arrive by later aftn or early eve. Vis may
drop to MVFR, but confidence is lower since the HRRR models breaks
the smoke down as it moves east. Otherwise, gusty winds Southerly
to westerly winds will continue.
&&
.LKN WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
92/94/94
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
728 PM CDT Wed Oct 11 2017
.UPDATE...
728 PM CDT
Northeast flow continues this evening but ever so gradually
easing. The low clouds are locked in, with local AMDAR soundings
indicating a moisture depth of 4,500-5,000 ft, with the upper 1,500
ft of that or so within the inversion. That`s not good for any
clearing possibly through much of tomorrow with the incoming light
winds under the surface ridge. The drizzle and patchy light rain
in northeast and north central Illinois is now mainly driven by
lake-induced instability. With flow easing and veering slightly
more east overnight, and a tad more drier air, the intensity and
coverage of drizzle should wane overnight. Cannot rule out a few
spits lingering into early morning close to the shore based on
forecast RAP profiles.
MTF
&&
.SHORT TERM...
1259 PM CDT
Through Thursday...
The system responsible for last night`s rain is lifting away from
the region. Any lingering showers should come to an end through the
afternoon today, but an expansive area of low stratus will remain in
place through tonight and likely, through tomorrow as well. Latest
forecast sounding suggest that some drier air will overspread the
nearly saturated lower levels late tonight and tomorrow, bring a
chance for some patchy drizzle and for the late night into early
morning hours. The blanket of stratus will also limit the diurnal
temperature trends with temps topping out today in the low 60s.
Lows tonight are expected to be in the low to middle 50s, but
highs tomorrow should only be a couple degrees higher than today,
reaching only the low 60s.
&&
.LONG TERM...
241 PM CDT
Thursday night through Wednesday...
Main concern in the extended is multiple rounds of rain Friday
night into Sunday. After an above average end to this week, next
week starts with more seasonal temperatures and a slow warm up
through mid week.
Dry weather is expected Friday as the upper level ridge hangs
over the region. Warm air advection will also result in high
temps in the low to mid 70s. Cloud cover will play a big part in
how efficiently we warm Friday with more cloud cover leading to
cooler temps. Precip forms to our north and west along an upper
level vorticity streamer Friday evening. Showers and a couple of
embedded thunderstorms spread across the region Friday night.
A surface low surges from northwest Missouri to Quebec Saturday
afternoon to Sunday afternoon. The low`s warm front lifts through
the region Saturday bringing another surge of warm air. High
temps will range from the low 70s along the IL/WI state line to
around 80 south of I-80.
Morning showers dissipate, but I`m expecting scattered afternoon
showers to form within the warm sector. GFS suggests CAPE and
shear values that could support strong to maybe severe storms.
Similar to many systems lately, CAPE will be the limiting factor
for severe storms. PWATs will be well above average at around 2
inches, and this much liquid could lead to heavy rain. The line
of showers and storms pushes east of the forecast area Sunday
morning or early afternoon along with the low`s cold front.
Northwest winds and a push of cooler air follow the front with
highs Sunday in the 60s. Sunday night looks particularly blustery
as a secondary upper level trough and cold pool spread across the
region. Wind gusts around 25 MPH are possible. Lows in the low to
mid 40s are expected. The upper level trough should only produce
precip over the lake early next week.
The dry period continues through mid next week under high pressure.
Temps also climb into the upper 60s by mid week as well.
JEE
&&
.AVIATION...
For the 00Z TAFs...
IFR stratus, fog and drizzle are expected to persist overnight,
and are the main aviation forecast concerns through this TAF
period.
Surface low pressure continues to pull away from the area across
the Upper Ohio Valley early this evening. A weak surface trough
lingers across central IL/IN however, with moist east-northeast
low level flow off the lake resulting in persistent low cigs and
intermittent light rain/drizzle. Forcing for producing precip
should continue to weaken this evening, allowing a decrease in
intensity of precip and somewhat better IFR/MVFR vsbys...though do
expect a very gradual decrease in cig/vis conditions into solid
IFR overnight. Vsbys around 3SM and cigs 600-700 ft are likely by
morning.
Low level winds will turn light southeast Thursday, and will
eventually shift a warm front north of the area by afternoon. This
should result in a gradual improvement back to VFR vis and MVFR
cigs.
Ratzer
&&
.MARINE...
241 PM CDT
Kept current Small Craft Advisory as is as winds and waves will
slowly subside through tonight.
Low pressure over Ohio weakens as it continues east, and high
pressure spreads over the Great Lakes this evening. East winds
diminish this evening and veer to southwest by Thursday night. A
stationary front over the southern end of the lake Friday night
will lead to north winds to the north of the front and southerly
winds to the south of the front.
The next surface low forms over northwest Missouri Saturday
afternoon. The low`s warm front surges two thirds up the lake
before the low passes over the lake Saturday evening/night. Wind
gusts up to 30 kt are expected. Winds become north to northwest
behind the cold front and gales are expected Sunday.
High pressure spreads over the Great Lakes Sunday night and then
passes south of the lakes Monday night. West to southwest winds
10-20 kt are expected early to mid next week.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...IL nearshore waters until 5 AM Thursday.
Small Craft Advisory...IN nearshore waters until 11 PM
Wednesday.
&&
$$
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Area Forecast Discussion
National Weather Service Melbourne FL
846 PM EDT Wed Oct 11 2017
.UPDATE...
GOES-16 water vapor imagery combined with the most recent RAP
analysis indicates a significant punch of low- to mid-tropospheric
dry air advecting across the area. As a result, radar is nearly
void of returns this evening, save for an isolated shower or two
and some weak convergent signatures over the marine waters.
Moisture in association with a wave over the Bahamas will build
across our southeastern zones late tonight, so will maintain a low
chance for showers over portions of the Treasure Coast waters as
well as Martin and St. Lucie counties closer to sunrise.
&&
.AVIATION...
Generally VFR with northeast winds increasing after sunrise
Thursday. Building moisture through the day on Thursday will
support an increased coverage of showers, especially KVRB-KSUA
corridor.
&&
.MARINE...
Tonight/Thursday...ENE/NE winds approaching 10-15 kts with 15-19
kts offshore/south of Sebastian Inlet. Seas building to 3-5 ft
nearshore and 5-6 ft offshore overnight, up to 7 feet by Thursday
afternoon. Cautionary statements in effect for the offshore
marine legs tonight and will likely be needed over the nearshore
waters on Thursday.
&&
.HYDROLOGY...Moderate to Major flooding continues along the upper
and middle St. Johns River basin. Limited rain chances through mid
week will allow for river levels to remain fairly steady, or show
very slow decreases through this period. Higher rain chances are
expected From late Thursday or Thursday night through this weekend.
Difficult to pin down rain amounts, however any locally heavy
rainfall over the basin will aggravate standing water concerns and
temper the slow decline of water levels.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 69 86 73 86 / 0 10 20 40
MCO 69 89 73 88 / 0 10 20 50
MLB 74 87 78 87 / 10 30 50 60
VRB 75 86 77 86 / 10 50 60 60
LEE 71 89 71 90 / 0 0 10 30
SFB 70 88 72 88 / 0 10 20 50
ORL 71 89 73 88 / 0 10 20 50
FPR 75 86 76 86 / 10 50 60 60
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Ulrich/Pendergrast
Area Forecast Discussion
National Weather Service Marquette MI
746 PM EDT Wed Oct 11 2017
.SHORT TERM...(This evening through Thursday)
Issued at 355 PM EDT WED OCT 11 2017
Water vapor imagery and RAP analysis show a trof over the western
CONUS with axis just inland. Downstream ridging extends from the
central Plains to northern Ontario. A shortwave is moving across
southern Lower MI toward the Lower Lakes. In its wake, abundant low
cloudiness lingers back to se MN/east half of IA, and these clouds
will be the main fcst issue heading thru the short term part of the
fcst. Sct-bkn lake effect stratocu has been streaming off northern
Lake MI into far s central Upper MI/ne WI today. These clouds are
now dissipating under moderating air mass and daytime mixing. There
were some clouds off Lake Superior into the Huron Mtns and the
Keweenaw earlier in the day as well. Otherwise, abundant sunshine
has been the rule this aftn across the area. For the most part,
temps have risen into mid 50s to lower 60s.
A shortwave ejecting from the western trof will reach
Saskatchewan/Manitoba on Thu, supporting a deepening sfc low lifting
ne into Manitoba. With sfc high pres shifting to Quebec, flow btwn
these 2 pres centers will increase across Upper MI tonight/Thu.
Although centered to the e, the sfc high pres will ridge back toward
the Upper Lakes thru Thu morning, and this will keep low-level flow
more out of the se, delaying the advection into Upper MI of the
aforementioned low clouds lingering back across southern WI into
adjacent MN/IA. However, the development of an upslope lake
modified/moistened se flow off Lake MI into the radiationally cooled
w half or so of the fcst area should lead to the formation of
stratocu/stratus later in the night. Will probably see quite a bit
of cloudiness over roughly the w half of Upper MI on Thu as
additional cloud cover from the s moves into the area. Areas that
see downsloping under s to se winds have a better chc of seeing
breaks for sunshine. Clouds will increase into the eastern fcst area
in the aftn. Min temps tonight will be higher than last night due to
stirring winds and eventually some clouds. 40s should generally be
the rule though there will be some 30s in the traditional cold spots
and a few locations along the lakeshores may not drop blo 50F. Cloud
cover will hold back temps from their potential on Thu. Highs of 60-
65F should prevail.
.LONG TERM...(Thursday night through Wednesday)
Issued at 418 PM EDT WED OCT 11 2017
Only significantly impactful weather in the long term is gusty winds
and more so large waves/lakeshore flooding issues Sun into Sun night.
Focusing in on those impacts, models continue to agree that a
strong shortwave will drive a deepening SFC low from near Green Bay,
WI at 06Z Sun to the SOO around 12Z Sun. The low is modeled to be in
the 995-1,000mb range as it moves nearby. This will lead to gusty NE
winds early Sun that will turn N then NW through the day and
evening. At this point it looks like some areas near central and
eastern Lake Superior could see gusts up to 40mph, so nothing too
significant there. The bigger issue may be lakeshore flooding/beach
erosion as NE-N waves over south-central and eastern Lake Superior
are forecast to be around 10 feet Sun into Sun night. Lake Superior
water levels are 6 inches higher than this time last year and 2
inches below the October record high. Last we used 14 foot waves as
a benchmark for a lakeshore flood advisory, but we may need to flex
that down given the elevated lake levels. At this point, don`t
expect significant flooding, but certainly will see beach erosion
issues if the forecast holds up. Will highlight in the HWO/EHWO for
now. Pulled wind maxima from over the south-central and eastern lake
to land since model resolution doesn`t handle that well at that time
period, and that (along with re-running winds gusts) was the only
change made to the blended initialization.
It is possible that some snow may be seen inland from Lake Superior
Sun night in the colder air behind the system and as another
shortwave moves through, but only trace accumulations would be
possible at most and only on grassy surfaces.
Otherwise, blended initialization handled things well and impacts
are none to minor.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 745 PM EDT WED OCT 11 2017
VFR conditions will prevail at KIWD/KCMX/KSAW thru this evening.
Late tonight into Thursday morning, advection of low-level
moisture/clouds from the south and southeast as well as upslope flow
off Lake MI will lead to MVFR cigs developing. The ceilings may mix
up a bit higher, possibly VFR at times Thursday; however, the
ceilings will likely drop back down after sunset.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 355 PM EDT WED OCT 11 2017
...NE to N gales possible east half of Lake Superior on Sunday...
Tightening pres gradient btwn high pres to the e and low pres
tracking ne to s central Canada will lead to an increase in winds to
generally 15-25kt across much of Lake Superior tonight thru Thu
night. Winds will diminish slightly for Fri/Fri night as weakening
cold front associated with low pres tracking to Hudson Bay moves
across the Upper Lakes. New low pres will then lift ene along the
frontal boundary this weekend, passing across the Great Lakes Sat
night/Sun morning. Depending on the strength of the low, there may
be a period of NE to N gales on Sun over the e half of Lake
Superior. Winds should be down to mostly under 20kt by Mon.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...Titus
AVIATION...KEC
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Paducah KY
730 PM CDT Wed Oct 11 2017
.UPDATE...
Issued at 730 PM CDT Wed Oct 11 2017
Several modifications made to the near term forecast. We upped
lows tonight, given the clouds are going nowhere, per the light
mean 950-900mb flow from the north. Also raised cloud percentages
considerably all areas, with some breaks expected over the Ozark
Foothill region. Held on to the clouds longer farther west into
the CWFA for Thursday as well given the continued weak flow. This
will result in lower highs, especially from SW Indiana into the KY
Pennyrile over to the Ohio River. The NAM and RAP are the only
models that seem to have a handle and were followed closely. We
generally don`t concern with fog unless vsbys are at or below 1
mile. This an little observable sfc/blyr convergence through 12z
means drizzle is unlikely (stays north of the area). Patches of
insignificant P6SM drizzle can`t be ruled out entirely. So just a
dry, cloudy overnight forecast.
CN
&&
.SHORT TERM...(Tonight through Friday night)
Issued at 311 PM CDT Wed Oct 11 2017
Stubborn deck of low level stratus has maintained a firm hold on
much of the area today. It is a fairly shallow layer with soundings
showing the depth less than 1000 feet. Some clearing has worked into
Carter/Ripley Counties and a fast erosion of the clouds is occurring
just to our south in Tennessee. The question is how far north does
this clearing make it before halting for the day. The northward
extent should be reached within the next hour or so, with the rest
of the region socked in through the night and into the morning
tomorrow. There may even be some southward expansion of the clouds
after dark.
Guidance is hinting at good fog potential overnight, but with
wind staying up just enough and clouds in place, wouldn`t expect
widespread fog. Stuck with the patchy fog mention for most areas.
May even be some light drizzle, especially in our northeast
counties late, closer to the surface trough pivoting through
Indiana.
Clearing should begin to progress from southwest to northeast
through the morning hours tomorrow, but clouds may stick fairly
tough through much of the afternoon in the Evansville Tri-State
area. With some sunshine, temperatures should warm nicely back
around 70/low 70s. If clouds linger longer in the east,
forecast highs may be too warm tomorrow.
Upper level heights rise on Friday in response to ridging
building north from the southeast U.S. This in combination with
southerly winds on the backside of surface high pressure will push
temperatures around 80 by Friday.
.LONG TERM...(Saturday through Wednesday)
Issued at 311 PM CDT Wed Oct 11 2017
Fairly high confidence in extended forecast with near record warmth
on Saturday replaced with cooler air early next week. We only have
one shot at precipitation during this time period, and that comes in
on Sunday into Sunday evening.
Upper level ridging will be in place over the southeast U.S. to
start the period, with an 850 thermal ridge extending into our area
on Saturday. This will lead to well above normal temperatures, close
to records in the mid to upper 80s. (Record highs are 88 in Paducah,
87 in Cape Girardeau, 90 in Evansville.)
On Sunday, shortwave energy moves across the Great Lakes region with
a cold front pushing into our area. The overall forcing and dynamics
aren`t near as impressive as they are further to our north, but
should still see a decent shot of some rain move from northwest to
southeast Sunday into Sunday evening. Still some subtle timing
differences with the 12z GFS remaining a bit faster with moving the
precipitation out. Instability looks marginal at best, so kept in
only slight chance of thunder with this system.
Surface high pressure builds back into the region on Monday and
persists for much of next week. This will result in temperatures
closer to normal or even a touch below normal for this time of year.
Highs may not make it out of the 60s for many locations on Monday
before rebounding into the low 70s Tuesday into Wednesday. With the
high expected to be overhead on Monday night, temperatures should
drop off nicely with MOS guidance hinting at even some upper 30s
possible in our northern counties near Mt Vernon, IL. Won`t go quite
that cold yet, but did nudge lows down a degree or 2 from what the
blend generated, into the mid 40s.
&&
.AVIATION...
Issued at 650 PM CDT Wed Oct 11 2017
Low level moisture will cause aviation headaches over the next 24
hours. Cigs are mainly MVFR and should stay that way through tonight
and Thursday. Any potential IFR conditions early Thursday morning
look to be short-lived. The chance of clearing on Thursday afternoon
appears to be low, but there remains a potential for VFR conditions
during the afternoon. Winds will be light and variable. Fog should
not be too much of an issue due to cloud cover.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
SHORT TERM...SP
LONG TERM...SP
AVIATION...MY
Area Forecast Discussion
National Weather Service Blacksburg VA
741 PM EDT Wed Oct 11 2017
.SYNOPSIS...
A cold front will approach then cross the area overnight. Thursday
into Friday, a nose of high pressure will work its way south along
the lee of the Appalachians. This wedge will give way on Saturday in
advance of another cold front, which in turn will cross the region
on Monday.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 741 PM EDT Wednesday...Surface low analyzed near
Pittsburgh extends a surface cold front southwestward through
central WV. Warm and conditionally unstable air mass lies ahead
of it across the forecast area, though a fair amount of
southwest/west- southwest surface wind exists limiting
convergence/convective coverage. May see some increase along the
frontal boundary as it moves into eastern WV in the next hour
or two, though past few runs of the HRRR have become less and
less enthused on those prospects. Generally reduced PoPs
areawide but kept any mention of isolated to scattered PoPs
across WV and in our southern Shenandoah and central VA Piedmont
counties through late evening. Air mass remains unstable enough
for a couple thunderstorms though that will be waning with
sunset. In fact the surface front largely clears the forecast
area prior to midnight.
Also made some adjustments to cloud cover. Late-afternoon
visible/infrared imagery depicted an expansive blanket of post-
frontal stratus, its eastern extent currently across central KY
and eastern OH. Recent RAP and 18z NAM BUFKIT RH profiles show
shallow saturated layer atop a strong subsidence inversion at
Beckley setting in after around 2 AM. So I did opt to increase
sky cover significantly from eastern WV into the western part of
the New River Valley and the Mtn Empire in VA. At least some
stratus associated with developing post-frontal wedge in eastern
VA may potentially intrude as early as the pre-dawn hours in
Buckingham, Appomattox and Charlotte Counties. So much of the
area should be beginning to turn at least partly cloudy.
Previous near-term discussion issued at 230 PM follows...
A frontal boundary lifted slowly north during the course of the day,
and is currently positioned across the eastern panhandle of West
Virginia, eastward into the Delmarva Peninsula. A cold front was
approaching our region from the west, located currently from roughly
central Ohio, south into eastern Kentucky and Tennessee. Across the
forecast area, very warm temperatures with high dew points for this
time of the year cover the area. Instability was noted across the
entire area, with the greatest over Southside Virginia and
neighboring north central North Carolina. Over the past few hours,
showers have been developing over this area, with the greatest
concentration currently over central Pittsylvania County, VA.
Heading into the evening, the activity will continue across the
southeast portion of the area, but is expected to also increase
across the northwest with the approaching, and subsequent arrival,
of the cold front. Isolated thunderstorms cannot be ruled out,
especially over the southeastern parts of the area. The bulk of the
precipitation will end by midnight, with lingering showers across
the far northeast section of the area through sunrise Thursday.
There will be a slight chance in airmass, as somewhat lower dew
points arrive behind the cold front. However, conditions still will
remain above normal for this time of year. Low temperatures will
range from the mid to upper 50s across the mountains to the lower to
upper 60s across the Piedmont.
During the day Thursday, the cold front will continue progressing
out of the area, all the while a nose of high pressure works its way
south along the lee of the Appalachians. Anticipate a northeasterly
flow to advect low level moisture into the region prompting plenty
of cloud cover and light rain/drizzle/fog expanding in coverage
across primarily eastern sections of the forecast area. By sunset,
the light rain/drizzle is expected to have expanded southwest into
the Foothills of North Carolina. The far western sections of the
area will remain outside this building wedge of high pressure and
experience little or no precipitation. High temperatures will range
in the 70s, with the coolest readings across the northern and
northeastern sections of the area.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 210 PM EDT Wednesday...
Strong wedge in place Thursday night and Friday with abundant
moisture from the surface through about 5000 feet AGL. Mid and upper
levels will be dry. No question about overcast sky over the
mountains and through the foothills and piedmont. Western edge of
clouds will be just west of Lewisburg to Bluefield to Boone. Not as
obvious is the occurrence and amount of any light rain.
Isentropic lift and upslope better over eastern slopes of the
central Appalachians on Thursday night than on Friday night when
the lift shifts into the southern Appalachians. Will have the
highest probability of rain overnight Thursday night.
Wedge and low moisture erode on Saturday. Winds become more
southwest on Saturday night. Clouds will keep temperatures nearly
steady on Friday but anticipate enough peaks of sun on Saturday
to result in warmer temperatures.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 200 PM EDT Wednesday...
Models starting to come into better consensus with the timing and
location of a synoptic scale trough crossing the eastern United
States Sunday and Monday with the ECMWF on the slower side of the
solutions.
Strong cold front crosses the Mid Atlantic region early Monday and
both GFS and ECMWF showing good upper diffluence ahead of the front
on Sunday night. Most favorable location for thunderstorms ahead of
the front on Monday will be in the piedmont of Virginia and North
Carolina based on the timing of the front. Rest of precipitation
will be post frontal.
ECMWF consistent in showing 850MB temperatures behind the front
dropping into the +4 to +8 range. Precipitable water values drop
well below one half inch. Air mass begins to moderate Wednesday.
Expect low level winds up to 30 knots with pressure rises on 2 to
5MB/3hr behind the front with decent cold air advection so will be
increasing the winds on Monday afternoon and Monday night. As high
pressure moves in Tuesday winds will diminish.
&&
.AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
As of 741 PM EDT Wednesday...
VFR initially as we await the approach and eventual passage of a
surface cold front which as of this writing was located across
central WV. May see isolated to widely scattered showers or even
a thunderstorm as this feature sweeps across the airspace
through 03z. Potential for MVFR visibilities in showers which
affect any specific TAF; treated as prevailing VCSH mainly for
western terminals with TEMPO MVFR showers.
Expect a deterioration in flight categories for the after-
midnight and overnight hours behind the cold front. Conditions
begin to deteriorate earliest at Lewisburg and Bluefield with
post-frontal IFR to LIFR stratus; patchy areas of fog with MVFR
to IFR visibility possible pretty much anywhere but most likely
where rainfall occurred today. While stratus in the west begins
to erode Thursday morning to a VFR deck, we then start to
develop wedge conditions for Thursday with high likelihood of
MVFR to LIFR ceilings along with areas of drizzle or light rain
for sites within and east of the Blue Ridge and Alleghany
Highlands. Some guidance brings these conditions into Lynchburg
as early as mid- morning; general trend is for a westward
deterioration in flight categories through the day.
Winds begin west/southwest 4-6 kts then become northwest with
FROPA through midnight; winds steadily continue to veer
overnight to a northeasterly direction 4-8 kts on Thursday.
Extended Aviation Discussion...
Sub-VFR conditions will continue across central and eastern
parts of the area Thursday afternoon through Friday night.
Saturday, the lee side wedge will give way to increasing
southwest flow ahead of our next synoptic scale upper trough
and associated cold front. This will allow for more areas to
experience VFR conditions, a trend that will continue into
Sunday.
Sunday night into Monday, a substantial cold front is expected
to cross the area with scattered showers and some storms. Sub-
VFR conditions are expected to accompany the stronger
showers/storms. Also, in the wake of the cold front, lingering
moisture in the west will likely manifest as some upslope sub-
VFR ceilings Sunday night into Monday morning.
&&
.CLIMATE...
Record high temperatures for Wednesday October 11th...
Roanoke......89...1919
Lynchburg....89...1919
Danville.....90...1954
Blacksburg...80...2010
Bluefield....80...2010
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...DS
NEAR TERM...AL/DS
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...AL/DS
CLIMATE...JH
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Thursday)
Issued at 241 PM CDT Wed Oct 11 2017
19Z water vapor imagery shows an upper trough over the Pacific
Northwest with a flat upper ridging along the Gulf Coast. This
leaves a dry west southwest flow aloft over the central plains. At
the surface, a ridge axis was sliding east of the area as high
pressure weakened.
The forecast for tonight and Thursday is for continued dry weather
as there is little or no forcing within the flow aloft and dry air
in mid and upper levels. The main concern is for some possible
ground fog. Some of the forecast soundings show the boundary layer
saturating overnight and there should be relatively good conditions
for radiational cooling. The question is whether there is enough
moisture in the boundary layer. The RAP and NAM show surface
dewpoints holding around 50 overnight. Except for areas where the
stratus has lingered, dewpoints have mixed out into the lower and
middle 40s. So am a little hesitant to buy into the forecast
soundings boundary layer moisture. Winds will likely be light, but
there should be enough of a gradient for winds to keep from going
calm. So at this point any ground fog looks to be in the typical low
lying areas near bodies of water. Lows tonight should fall into the
mid 40s. For highs Thursday, have trended them warmer. Models prog
pretty good low level warm air advection with 925MB temps warming to
around 21C across central KS. With good insolation, think highs will
be in the middle 70s to near 80.
.LONG TERM...(Thursday night through Wednesday)
Issued at 241 PM CDT Wed Oct 11 2017
Initial upper wave pushing east across the northern Plains settles a
cold front into the area late Thursday night, with all guidance
agreeing it will hang up across the area for the next few periods
as it becomes parallel to the mid- and upper-level flow. Initially,
the mid and upper layers are rather dry, but will need to watch
depths of the cloud layer and persistent low-level frontogenesis for
drizzle and perhaps a few showers behind the front in the
north and west Friday and Friday evening before moisture depths
rapidly increase, with PW values in the 1.5-2 inch range Friday
night into Saturday evening. Elevated showers and thunderstorms
will likely increase Friday night into early Saturday and play a
large role in severe weather potential for Saturday afternoon and
evening. Areas that stay in relatively clear air will likely see
ML CAPE values around 1200 J/kg and strong low- and deep-layer
shear, though mid-level lapse rates and low-level CAPE are not
impressive. Secondary front surges through Saturday night with the
remainder of the weekend looking dry. With the very high PW air
for this time of year and low-level baroclinic zone nearly
stationary for a period or two, there are ingredients in place for
heavy rainfall as well, though not too dissimilar to last
weekend, overall forcing for persistent ascent is not apparent.
The front`s location across the area also creates wide spreads in
high temperature potential for Friday and Saturday. Expect a much
tighter gradient than currently forecasted, with locations in the
north and west more likely to be cooler as opposed to warmer than
depicted.
Modified surface anticyclone settles in Sunday night and presents a
good environment for radiational cooling, though nature of this
airmass suggests anything more significant than a frost would be
unlikely. After a cooler Sunday, temperatures should modify into the
midweek as weaker zonal to northwest flow pattern builds overhead.
Differences increase in the pattern around Wednesday with models
struggling in how to handle energy in the fast jetstream over the
northern Pacific Ocean, but rich moisture availability is very
hard to come by locally and keeps the Monday to Wednesday periods
dry.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 612 PM CDT Wed Oct 11 2017
Have kept a VFR forecast going for the period. Some models
continue to pick up on radiational fog development tonight,
especially at TOP/FOE by early morning. For now, expect if
anything is to form it would be shallow and in low lying areas.
Southerly winds begin to pick up tomorrow after 18Z with gusts up
to 23 knots seen near MHK.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Wolters
LONG TERM...65
AVIATION...Heller