Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/05/18
Area Forecast Discussion...UPDATED
National Weather Service Charleston SC
947 PM EST Sun Nov 4 2018
A coastal trough will affect the area tonight and Monday before
a cold front sweeps through Tuesday night. A warm front will
lift north Thursday then a cold front will move through Friday
night. High pressure will then build in next weekend.
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
The coastal front is showing signs of moving closer to the coast
as weak low pressure develops along it. Temperatures along
portions of the Georgia and lower South Carolina coast have
risen 1-2 degrees within the last hour, even as rain falls.
Low-level convergence is steadily building along the coast as
the surface waves becomes better defined. This increased
convergence coupled with strong isentropic assent atop the
inland wedge and coastal trough will support widespread shower
activity across the coastal counties for the next few hours
until the surface waves passes off to the northeast.
Pops will range from 100% at the coast to 30-50% in the Millen-
Allendale-Cat Hole corridor. The rain could be moderate to
locally heavy at times, but no major flooding problems are
expected. Have seen A few lightning detections on both GOES-E
GLM and the LDN across parts of Southeast Georgia. Still think
the best instability will remain over the coastal waters, but
there looks to be enough elevated instability along the cool
side of the coastal trough to support a few tstms. Expanded a
slight chance of tstms to include all coastal counties. Still
think there is a non-zero risk for an isolated tornado along
parts of the Charleston Tri-County area, mainly along the
Charleston County coast, where the latest RAP still shows the
EHI peaking around 1 unit and SigTor reaching near 2 unites
ahead of the surface wave.
Pinning down lows is proving very tricky as hourly temperatures
will be driven by the ultimate position of the coastal trough
and frontal wave. Latest high resolution guidance supports a
slightly larger and warmer warm sector ahead of the wave. This
will result in temperatures slowly rising in a few areas,
especially along parts of southern South Carolina. Lows will
range from the lower 60s well inland to the mid-upper 60s at the
Conditions appear favorable for areas of fog to develop across
interior Southeast Georgia early Monday in the wake of the
surface wave. The fog will be the result of stratus build-down
and there are a number of guidance packages supporting dense
fog with vsbys 1/4 mile less. Latest NARRE-TL shows
probabilities of 60-70% for vsbys <1/4 mile roughly along/west
of an Allendale-Glennville line. Maintained "areas of fog" in
this region and will update the HWO include a mention for
possible dense fog development.
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
Shortwave troughing aloft will continue to dampen as it rides
northeast along the longwave trough as a trailing shortwave begins
to deepen while sliding east. By late in the day, this trough
develops more of a positive tilt while over the central U.S.
Locally, the forecast area remains near the broader mid-upper
longwave trough while better model agreement suggests the coastal
trough slides inland and weakens through the day, bringing
precipitation potential for much of the day, declining later in the
evening. Mostly dry conditions over land zones are expected
overnight into early Tuesday.
A surface cold front trailing a strengthening low pressure system
moving northeast across the Great Lakes region will cross the
forecast area late Tuesday night into early Wednesday morning. The
best forcing and associated risk of severe weather is expected to
remain farther inland and north of the forecast area. At least a
period of drying is anticipated behind frontal passage, but synoptic
models show the front stalling just south of the area, with moist
southerly flow likely leading to some degree of overrunning
precipitation which could spread over the forecast area Wednesday,
mainly during the afternoon and evening. Because of this, slight
chance to chance POPs will be maintained.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A broad upper trough remaining over the central United States
results in lower than normal forecast confidence in the long
term. Models have shown poor run-to-run consistency beyond
Thursday as there will be the potential for a series of fronts
to develop and affect the Southeast during the period. The one
feature that continues to appear is a cold frontal passage
Friday or Friday night.
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
KCHS: Showers will impact the terminal in some form through
about 05z with the bulk of the activity pushing east/northeast
as a wave of low pressure develops along the coastal trough.
Risk for tstms is low. MVFR vsbys/cigs will be possible during
this time with MVFR cigs lingering through mid-morning Monday
before lifting. Best chances for IFR look to remain west and
southwest of the terminal.
KSAV: Rain showers will impact the terminal through about 03z
after which the bulk of the activity will push northeast of the
terminal as weak low pressure develops along the coastal trough.
As the low pulls away, expect low stratus to overspread the
terminal from the west as the coastal trough is forest to
remain just offshore. The lowest conditions still look to remain
west of the terminal, but still expect IFR cigs to move in.
Right now, do not anticipate cigs any lower than 700 ft and
vsbys in light fog no lower than 4SM. MVFR will return by mid-
morning with VFR by noon.
Extended Aviation Outlook: Periods of flight restrictions will be
possible at both terminals through Tuesday due primarily to low
ceilings. Additionally, fog will be possible overnight Monday into
Tuesday, and shower and/or thunderstorm activity could briefly
reduce surface vsbys.
Tonight: The tightest pressure gradient is working up the coast
this evening ahead of a weak surface low developing along the
coastal trough. Extended the Small Craft Advisory for the South
Carolina waters through 1 AM for gusts to 25 kt. Winds are
expected to diminish as the coastal trough works to the coast
and low pressure develops along it. Advisory through 10 PM looks
fine for now.
Monday through Friday: Generally onshore flow 10-15 knots will
persist into Tuesday before veering northeast behind a passing
cold front late Tuesday into early Wednesday with a coincident
uptick in windspeeds which are still expected to remain below
Small Craft Advisory levels. Anticipate northeast flow to
persist through Thursday. The greatest chance for winds/seas
reaching Small Craft Advisory criteria will be Friday night into
Saturday behind a stronger cold front.
MARINE...Small Craft Advisory until 1 AM EST Monday for AMZ350-352.
Area Forecast Discussion
National Weather Service Memphis TN
910 PM CST Sun Nov 4 2018
A few light showers continue to affect portions the Mid-South this
evening as an upper trof continues to move through the area. The
trof will lift into the Ohio Valley by midnight. This should bring
an end to the chances of rain. The HRRR indicates that dense fog
may develop during the overnight hours especially across North
Mississippi and portions of West Tennessee. The forecast already
has mention of patchy fog, but will monitor for a possible Dense
Fog Advisory. For now, current forecast looks good.
.DISCUSSION... /issued 322 PM CST Sun Nov 4 2018/
Skies have cleared across much of east Arkansas with cloudy skies
over the remainder of the forecast area. Temperatures this
afternoon range from the mid 50s to lower 60s. A large area of
light rain continues to move across much of north Mississippi and
a small portion of west Tennessee with some additional showers
about to cross the Mississippi River. All of this activity is
ahead of a weak cold front which is just west of the forecast
As this front moves through the forecast area tonight, rain should
move out of the region tonight. Skies should clear some overnight
and with light winds and wet grounds, some patchy areas of fog may
develop. Temperatures will be on the cool side with lows Monday
morning in the mid 40s to around 50 degrees.
On Monday morning, the cold front will lift back north through the
region as a warm front with some isolated showers possible. Behind
the warm front, milder air will move into the region allowing
temperatures to warm into the mid 60s to lower 70s. By Monday
afternoon, a strong cold front will be moving across the southern
plains and into western Arkansas. Numerous thunderstorms are
expected to develop ahead of this front and move into the forecast
area. As the front moves closer to the Mississippi River, there
will be a better chance for some of these thunderstorms to become
severe. The main threat with these storms will be damaging winds.
Tornadoes, locally heavy rainfall and large hail are also
possible. The main time frame for severe weather in our area will
start around 2 pm in east Arkansas and end around 2 am in
By Tuesday, the cold front will be east of the region so rain will
be ending in the morning over far eastern sections of the forecast
area. Temperatures will not be that much cooler than Monday with
highs in the mid 60s to lower 70s.
On Wednesday, another cold front will drop into the region from
the north. This front will produce some additional rain showers
for both Wednesday and Wednesday night. By Thursday, a storm
system will move into west Texas and move rapidly northeast
reaching the Ohio Valley by Friday morning. This system will bring
another cold front through the forecast area with more rain
expected for Thursday, Thursday night and Friday.
High pressure will start to build into the region by Friday
afternoon bringing dry weather and colder temperatures. The dry
and colder weather will continue through much of next weekend.
Low temperatures both Saturday morning and Sunday morning will be
in the 30s so some frost and even a freeze is possible.
Band of rain is moving very slowly east as a cold front stalls
and weakens. Clouds are breaking up across KJBR and KMEM with VFR
conds expected through much of the night. Fog is possible later
tonight. KMKL should keep a MVFR cig overnight as clearing line
will likely stall to the west. Low cigs will remain at KTUP with
dense fog likely late tonight. As the front lifts back north as a
warm front some dense fog could lift north into KMEM early Monday
morning. Confidence is not high enough to place in the TAF but
will be on the lookout. Low clouds will spread across the entire
area Sunday morning with south winds around 10 kts. A potent
system will push into the region Monday afternoon with numerous
SHRAs and TSRAs during the latter parts of the period.
Area Forecast Discussion
National Weather Service Marquette MI
641 PM EST Sun Nov 4 2018
.SHORT TERM...(This evening through Monday)
Issued at 317 PM EST SUN NOV 4 2018
WV imagery and RAP analysis indicated a mid/upper trough into the
central CONUS with a vigorous shortwave trough lifting northward
through central WI which supported a broad area of light to
moderate precipitation from ern MN through WI into IL. Colder air
north of the low has also resulting in bands of moderate to
briefly heavy snow from nw WI into western Upper Michigan snow has
accumulated to 1 to 3 inches. However, radar trends and sfc obs
showed that the snow was diminishing near KIWD/KLNL/KEGV with a
changeover to rain at KPBH/KRHI. Snow as finally increasing over
the higher terrain in north central Upper Michigan with minimal
Tonight, expect the snow to continue to diminish from south to north
as the stronger WAA/295k isentropic ascent lifts quickly to the
north. As the low moves toward western Lake Superior, warmer air
moving in from the south will also change the remaining to snow to
rain this evening. Temps should also climb to around 40 west half
to the low to mid 40s over the eastern cwa. The more significant
pcpn will shift into the east overnight in line with the stronger
moisture transport and remaining 700-300 mb qvector conv and
isentropic lift. With the dry slot moving into the west, much of
the pcpn may be drizzle with little pcpn where downslope sse low
level flow prevails.
Monday, there may some leftover light rain or drizzle in the
morning over mainly the east until the sfc trough axis moves
through the area. SW low level flow will bring slightly drier air
into the region. However, enough low level moisture will remain to
maintain the cloud cover and limit high temps to around 40 west
to the mid 40s east.
.LONG TERM...(Monday night through Sunday)
Issued at 258 PM EST SUN NOV 4 2018
Overall, we`re looking at an active weather week with chances for
precipitation almost every day with a couple of systems tracking
across the region and the arrival of what looks to be the first real
good shot at accumulating lake effect/enhancement snow later this
week and weekend. There is still quite a bit of uncertainty in how
these systems will evolve as they move across the Great Lakes;
however, we certainly will be on a cooling trend through the
upcoming weekend. The earlier part in the week expect day time highs
in the low to mid 40s and overnight lows in the low to mid 30s.
Through the end of the week, temperatures will gradually cool into
the teens and upper 20s for overnight lows and low to mid 30s for
Tuesday/Wednesday, the complicating factor with this time period is
the multiple waves moving across the Great Lakes Region. The first
is the southern stream lifting northeast out of the Plains and up
across the eastern Great Lakes, with the deepening area of low
pressure tracking further south and east than what model guidance
suggested over the last couple of days. Given the further southeast
storm track, impacts from this system will be well removed from the
Upper Peninsula. We will however see precipitation from the second
wave progged to dig across the northern Plains and over across the
Western Great Lakes. This wave will result in either the development
of a secondary low pressure system, or an extension of troughing off
of the main low pressure system well east of the region. With the
colder air still behind this secondary wave, it appears that most of
the precipitation will remain all rain through much of Tuesday.
Tuesday evening into Wednesday as the main 850mb low pivots east
across the area, colder air moving in from Canada will support the
transition over to snow. Expect lingering lake effect/enhanced snow
showers Wednesday across the northwest wind snow belts in western
Upper Michigan as cold air advection continues to drop across Lake
Superior. Further east, the colder air doesn`t look to arrive until
Wednesday night, switching lake effect/enhanced rain showers over to
Thursday through this weekend, lingering lake effect snow will become
enhanced at times as another wave digs south across the Upper Great
Lakes and supplies additional lift/support to deepening ongoing
convection. This will mean that at times snow showers will push
further inland from the typical lake effect snow bands. With 850mb
temperatures progged to drop as low -12 to -15C, certainly not out
of the question we could see moderate to heavy lake effect snow
showers at times.
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 640 PM EST SUN NOV 4 2018
As a weakening low pres system lifts from western WI this evening to
northern Ontario on Mon, pcpn will diminish tonight at all
terminals. Any snow or snow/rain mix at the beginning of the fcst
period will change over to all rain by mid evening. While prevailing
IFR conditions are expected at KSAW tonight, KIWD/KCMX will likely
fluctuate btwn IFR and low MVFR. Overnight, KSAW will probably slip
down to LIFR under an upslope sse wind. Slightly drier air will
arrive on Mon, and that will likely lead to prevailing MVFR
conditions developing at all terminals.
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 258 PM EST SUN NOV 4 2018
East-southeast gales of 35 to 40 knots have begun to
overspread Lake Superior as low pressure lifts northeast this
afternoon. Expect these winds to continue through the overnight
hours, before gradually diminishing to 20 to 30 knots from the
southwest Monday morning. Winds look to further diminish to less
than 15 knots Tuesday as the pressure gradient relaxes with broad
troughing expected to develop over Lake Superior. However, this
period with lighter winds will be short-lived as winds become
northwesterly 20 to 25 knots Tuesday night through Thursday as
colder air works down across the Upper Great Lakes. Towards the end
of the week, another low pressure system progged to develop over the
Upper Great Lakes will need to be monitored for the potential for
Winter Weather Advisory until 7 PM EST /6 PM CST/ this evening
Gale Warning until 4 AM EST Monday for LSZ250-251-264-266-267.
Gale Warning until 10 PM EST /9 PM CST/ this evening for LSZ162-
Gale Warning until 1 AM EST Monday for LSZ244-245-263-265.
Gale Warning until 4 AM EST Monday for LMZ248.
Gale Warning until 1 AM EST Monday for LMZ221-250.
Area Forecast Discussion
National Weather Service Blacksburg VA
630 PM EST Sun Nov 4 2018
Low pressure forms along a coastal front tonight and sends clouds
and rain back into the area overnight. Cloudy skies along with
intervals of light rain and fog for Monday as a shallow wedge of
high pressure builds back southward. A stronger storm system
affects the region on Tuesday bringing a threat of showers and
thunderstorms, followed by drier weather under high pressure on
.NEAR TERM /THROUGH MONDAY/...
Update as of 630 PM EST Sunday...
Previous forecast looks fairly on track. Did adjust PoPs up
slightly along the Blue Ridge at the onset of precipitation
based on latest ConShort and HRRR. Increased moisture from the
south as mentioned in the previous discussion is beginning to
show itself in observations as cloud heights are noticeably
lowering across the forecast area. As this moisture continues to
increase ahead of the approaching frontal system, still can
reasonably continue to forecast precipitation becoming more
widespread across the forecast area around midnight.
As of 335 PM EST Sunday...
Established wedge in place across the mid-Atlantic, Appalachians and
Carolinas remains in place this afternoon with a continued dry
forecast through the late afternoon hours. Will start to see an
increase in clouds early this evening across our NC counties and
advancing northward across VA/WV into the mid-evening, as Atlantic
moisture associated with the southern end of a frontal boundary
which moved off the Atlantic seaboard late last week returns
northward atop the wedge. This shield of steady rains should be
infused by a southerly low-level jet progged to increase to 40-45
kts, eventually linking up with an occluding frontal system moving
into the eastern Ohio Valley and western Appalachians. Think the NMM-
WRF and the 3-km NAM showing steady rain in the Piedmont starting
early this evening is overdone. Have followed the later HRRR and the
GFS which supports rain beginning closer to midnight near and east
of the Blue Ridge. Areas including far southwest VA and into
southeastern WV likely will see steady rain beginning in the wee hrs
of Monday morning tied to the frontal occlusion. Overall expect rain
to be at least steady light to moderate-intensity. Rain should be
moving along to the northeast at a good clip given the strong winds
aloft, with rain moving into the Shenandoah Valley and north-central
VA toward the Monday morning commute. In terms of rain amounts,
stayed largely with a blend of WPC and the NAM, with rain totals
around a third to half-inch across the Southside and Piedmont,
quarter to a third of an inch across the Mountain Empire into
southeast WV, with higher amounts of half to three quarters an inch
along either side of the Blue Ridge. Opted for a non-diurnal
temperature trend with most areas seeing temperatures tending to
hover or slowly rise overnight with best warm advection. Lows mainly
in the 40s except low/mid 50s in the NC Piedmont and Southside.
Majority of model guidance shows the wedge, which had briefly
weakened/retreated north with the rain from overnight, eventually re-
settling back southward across the area on Monday. Other than in our
far southwestern counties, expect a cloudy, gray Monday across
the forecast area as moisture remains trapped under a stout
temperature inversion. Though the bulk of the steadier rains
will have ended early Monday, have shown limited chances for
very light rain or drizzle, and with light north winds did
include patchy mist or fog. Temperatures likely to rise only
very slowly on Monday mainly in the 50s given overcast, though a
few lower 60s possible towards the Mountain Empire into Mercer
County where some breaks in overcast look likely.
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 230 PM EST Sunday...
Dynamic upper trough to the northwest Monday night will push its
associated cold front to just west of the Appalachians by daybreak
Tuesday. This should also aid deepening warm advection allowing the low
level wedge to break down from southwest to northeast overnight as a
warm front lifts north across much of the region by Tuesday morning.
Some degree of warm advection showers likely with the passage of this
boundary and also within the increasing warm sector through midday
Tuesday. However coverage remains uncertain espcly given much stronger
lift/convergence with the cold front to the west, but appears still
enough for increasing pops to likelys west Monday night at this point.
Other concern with winds mainly along the western ridges as the 85h jet
ramps up to around 50 kts later Monday night. This may produce gusts to
around advisory levels BLF vicinity late Monday night into early
Tuesday. However these potential higher speeds may be more associated
with showers given more of a southwest trajectory, and model soundings
showing the stronger winds above the near surface stable layer. Lows
overall in the 50s espcly early before likely rising with the exodus of
the wedge late.
Cold front crosses the region from the west on Tuesday with guidance
perhaps a bit slower than previous given best support lifting by well
to the northwest. Scenario still appears to suggest residual showers
over the mountains Tuesday morning with either these fading or some
redevelopment of narrow bands just east of the Blue Ridge Tuesday
afternoon. These bands again low topped with perhaps little thunder and
possibly embedded within the very strong unidirectional wind field
aloft. Latest models suggest best shot at organization and wind
producing severe storms across the southeast counties around mid
afternoon before quickly exiting to the southeast per consensus. More
expansive shower/cloud coverage early on could also play into limiting
already weak instability, but likely overcome by shear espcly given
helicity off latest progged soundings. Thus will beef up pops some for
more linear aspects to shower/storms and keep severe mention in the HWO
per the going DAY3 outlook. Otherwise breezy and mild with highs 60s
mountains to low/mid 70s east.
Front exits the region Tuesday evening allowing a very fast zonal flow
aloft to take shape with high pressure bridging in from the northwest
into Wednesday night. This looks to bring in much drier air espcly
aloft by Wednesday under west/northwest flow. Brief punch of stronger
winds will be possible Tuesday night behind the front but given only a
25-30 kt 850 mb jet and weak cool advection, appears will stay below
advisory levels, with less wind Wednesday into the overnight under the
ridge axis. Also post frontal upslope moisture quite shallow so expect
only some spotty showers at most far northwest Tuesday night before
things clear out Wednesday despite lingering high clouds. Will see
temps lower about a category or two behind the front but overall still
above normal with mostly 60s Wednesday, except around 70 east given
.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 215 PM EST Sunday...
Flat 500 mb flow will again sharpen up from the southwest heading into
the end of the week in response to the next strong upper low pivoting
east toward the Great Lakes by Saturday. This backing flow should again
start to bring overrunning moisture back northeast toward the area
during Thursday with possible deeper moisture over the region Thursday
night into Friday evening. However model spread has become even larger
today with quite a difference in some phasing northern/southern energy
and others much flatter under more sheared upper support. This would
include the wetter operational GFS/CMC solutions from yesterday, that
have switched to a much more shunted scenario per weak low pressure
either offshore or to the south. This in contrast to the stronger 12z
ECWMF and FV3-GFS which support a more pronounced swath of deeper
moisture heading up across the region later Thursday night into Friday
with a subsequent frontal passage Friday night. Since this remains more
consistent with trends from yesterday and still supported by a few GFS
ensembles members will keep higher pops during this period before
tapering off Friday night when a few snow showers could still occur
over the west. Otherwise highs mostly in the 50s to lower 60s
Thursday/Friday pending clouds and eventual rainfall to end the week.
Secondary shortwave swings by to the north over the weekend allowing
better cold advection to get a southeast push resulting in drier and
colder weather for the weekend. Latest progs suggest that the coldest
air will remain north but enough cold advection Saturday to keep highs
40s west to low 50s east and similar Sunday but under less wind.
Coldest night also likely Saturday night as the surface high settles
overhead allowing for lows mostly in the 20s to around 30 east.
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 630 PM EST Sunday...
Poor flying conditions are expected through the TAF period as
increasing moisture riding into the region on a low level jet
will combine with an approaching frontal system to drop ceilings
and visibility to sub-VFR in low clouds, rain, and fog. Any
location that will begin in VFR will see those conditions
deteriorate within the next couple of hours. Rain could be heavy
at times overnight, particularly out east. By the morning,
heaviest rains should be finished however the wedge that will
weaken slightly with passage of the front will re-establish
itself creating gloomy conditions for Monday with continued low
ceilings and lingering drizzle and fog at many locations
throughout the day.
Winds will be from the east/southeast and light, but a bit more
pronounced, going into the forecast period than it will become
tonight, changing to very light and variable tonight through the
end of the forecast.
Forecast confidence is high on conditions being sub-VFR through
this TAF period, but does wane as far as timing out and severity
of MVFR and IFR conditions. Further, latest LAMP guidance does
suggest that LIFR conditions could be possible for short periods
of time at some locations, however have opted not to advertise
it in the TAFs themselves as enough uncertainty is already in
play regarding changes to the conditions.
Sub-VFR to continue into Monday night with trapped moisture
under wedge, periods of low clouds and intervals of mist likely.
The first of a couple of major weather systems digs into the
southeast U.S. on Tuesday. Winds, low ceilings, and low
visibilities in showers and thunderstorms can be expected, with
a period of high winds possible.
Improvement in ceilings/visbys likely Wednesday though still
breezy until Wednesday evening. Second major weather system
affects the region on Thursday with good potential for sub-VFR.