Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/28/18
Area Forecast Discussion
National Weather Service La Crosse WI
540 PM CST Sat Jan 27 2018
.UPDATE...
Issued at 540 PM CST Sat Jan 27 2018
Pesky batch of convective showers has continued to march across
the area late this afternoon, driven by a weak lead shortwave in
concert with some pretty impressive 850-500mb lapse rates of 8+
C/km (what month is this again?). Don`t see any reason those won`t
continue moving east the next few hours and given trends, have
raised PoPs for many areas out ahead of those showers, though no
real accumulation expected (maybe even a little rain out east
where surface temps still near 40 in spots).
Bigger thing to watch is a stronger shortwave cruising
southeastward from southern North Dakota at the moment, slated to
track across our area later tonight. Per recent guidance and
observational trends, appears snowfall associated with this
feature (already ongoing across east-central South Dakota) may end
up a touch farther north than earlier expected - slightly closer
to I-90, though will need to watch trends closely the next few
hours. Upshot is we may realize a little more snow in some spots,
though less than an inch still appears likely. Will update as
needed the next few hours, and may end up needing to add in at
least some flurries on Sunday as lower clouds overtake the area
from the north where they`re currently widespread while much of
the cloud deck sits in the DGZ. For reference, widespread flurries
and even some light snow are ongoing to the north at the moment
and have been there all day. Welcome back to winter - the brief
respite was nice!
&&
.SHORT TERM...(This evening through Sunday)
Issued at 328 PM CST Sat Jan 27 2018
At 3 PM, a cold front was producing a broken 6-10K deck of clouds
across southeast Minnesota and northeast Iowa. These clouds will
move across western Wisconsin late this afternoon and early this
evening. Temperatures were in the 30s and 40s ahead of this front
and ranged from the mid 20s to lower 30s.
Further upstream, a much stronger short wave trough was located
over the Dakotas. This system will move through the region after
midnight tonight and then depart the region on Sunday morning. The
RAP quickly saturates the air mass up to 700 mb along and south of
Interstate 90. While there is only about 50 to 75 mb in the
dendritic growth zone, it is co-located with the best omega. This
will increase the snow to liquid ratios into the 15-20 to 1 range.
With liquid totals up to 0.02 inches, snow totals will likely
range from a trace to around a half inch.
With 925 mb temperatures falling into the -9 to -15C range, high
temperatures will only range from the teens to upper 20s on
Sunday.
.LONG TERM...(Sunday night through Saturday)
Issued at 328 PM CST Sat Jan 27 2018
On Tuesday afternoon and evening, a warm front will move east
through the region. Like the past couple of days, it looks like
the best saturation will take place north of Interstate 94. It
continues to look like snow totals will be up to 2 inches.
On Wednesday morning, a cold front will move southeast through the
region. It continues to look like this front will only produce
some light snow with its passage. There is still some uncertainty
on how warm it will get ahead of this front. The ensembles are
ranging anywhere from 2 to 4 standard deviations with their
maximum temperatures.
For Friday night into Saturday, the models continue to differ on
whether a low pressure system will move east through the mid
Mississippi River Valley. While the operational ECMWF continues to
show this, there are many different solutions amongst its family
members. Some of these are even in agreement with the operational
GFS, therefore, there remains much uncertainty on the snow
chances and temperatures for this time period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 540 PM CST Sat Jan 27 2018
Fast-moving and narrow batch of precipitation will impact LSE
through 01Z with some rain/snow showers, but little impact
expected, save for perhaps a brief period of MVFR conditions.
Bigger thing to watch is later tonight as a stronger system tracks
across the area. Per current trends, looking like this one may end
up a little farther north than earlier expected, with increasing
potential for a 2 or 3 hour window of mainly light snow for both
LSE and RST, during which conditions could touch IFR at times but
with any accumulation mainly under an inch. Will be watching this
closely the next few hours with some slightly refinements to the
forecast possible. As that system departs, a more widespread MVFR
cloud deck should arrive along with much colder air by late
morning and through the afternoon, with some occasional flurries
or even light snow also possible under those clouds. Winds will
shift northwest then more northerly tonight into Sunday, holding
mainly 7 to 12 knots but potentially a little more gusty behind a
passing cold front this evening.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
UPDATE...Lawrence
SHORT TERM...Boyne
LONG TERM...Boyne
AVIATION...Lawrence
Area Forecast Discussion
National Weather Service Charleston SC
1047 PM EST Sat Jan 27 2018
.SYNOPSIS...
High pressure will move offshore tonight, then a frontal system
will impact the area Sunday and Sunday night. Cooler high
pressure will then return for the first part of next week,
before moving into the Atlantic during the middle of the week.
A cold front may affect the area next Friday.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
As of 1045 PM: A few areas of light rain have developed over
southeast SC and off the GA coast. Latest run of the HRRR
indicates that trends will slowly increase during the overnight
hours. I will adjust PoPs slightly higher into the late night
hours. Latest guidance continues to support the heaviest rain
arriving Sunday afternoon and evening.
As of 830 PM: Regional composite continued to indicate that
lower based marine showers tracking to the NW as higher based
showers inland were traveling toward the NE. Surface based
observations indicate that light rainfall was associated with
dBZ of 20 or greater. I will update the forecast to adjust PoP
timing and trends through tonight.
As of 635 PM: Regional radar composite indicated several small
showers across the forecast area. However, the primary band of
rain remained from coastal AL NE along the east facing slopes of
the Appalachians. The potential for rainfall will begin to
increase across the CWA later tonight. I will update the
forecast to increase sky cover and indicate slow cooling of
temperatures through the overnight hours.
Previous Discussion:
Remainder of the afternoon: Mostly cloudy skies will persist
with mild temps close to 70 degrees many areas falling back to
the mid 60s around dusk. Regional radars continue to show light
showers moving onshore in southeast GA and a few in SC, most of
this activity has failed to measure but we maintained slight
chance POPs in the forecast.
Tonight: The mid level ridge axis off the Mid Atlantic coast
will move further offshore while a series of short waves approach
from the west. Deeper moisture from the Gulf of Mexico will
surge into the lower Gulf Coast region while moist Atlantic air
in the lower level advects northward across the forecast area.
Widespread layered clouds will persist overnight with potential
for stratus well inland late. While the moisture builds, the
rain chances will mainly be in the chance range rain overnight
as better upper forcing will not arrive until late. There is a
potential for some fog in southern GA, especially if breaks in
the clouds develop overnight, or we see stratus develop sooner
than later and then build down. Since there are quite a few
uncertainties, we opted to leave mentions out of the grids but
we still may need some fog additions later tonight.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
Sunday will be quite an active day across the region. A broad upper
trough will begin to amplify as it shifts towards the east coast,
with several shortwaves to eject out of the southwest flow and cross
the forecast area. At the surface, a cold front will be approaching
from the west. There are still discrepancies between models on the
location and potential for a couple weak areas of low pressure to
develop later in the day - one over interior GA/SC and one over the
Gulf. These will eventually merge as they, and the cold front, push
off the coast early Monday. Given large scale forcing (vort energy,
upper divergence from the favorable right entrance region of the
upper jet, isentropic ascent) and abundant moisture, it should be a
fairly wet day. Categorical PoPs have been maintained. Instability
still looks minimal, so no mention of thunder in the forecast.
Forecast rainfall totals on average will be 1/2 inch to 1 inch, with
locally higher amounts. Should be able to squeeze another "warmer"
day with highs in the mid to upper 60s. Temperatures Sunday night
will be mild given rain and clouds around. Lows forecast in the low
to mid 50s.
Much quieter weather expected later Monday and Tuesday following
frontal passage. Surface high pressure will build in from the
northwest allowing cooler and drier conditions to return. The
stronger cold advection doesn`t set in until later Monday into
Tuesday so high temperatures will reach the low 60s on Monday, then
dropping to low 50s by Tuesday.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Cool high pressure will eventually move off the coast by late
Wednesday, bringing an increase in southerly flow and warming
temperatures. A cold front will move through Friday and Friday
night, potentially bringing a round of showers, followed by
somewhat cooler weather next weekend.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
High and mid clouds will continue to thicken through tonight,
likely remaining VFR before daybreak Sunday. Low pressure is
forecast to track from the FL panhandle at 12Z Sunday to the
midlands of SC by 0Z Monday. Forecast soundings and MOS agrees
that ceilings will lower through the daylight hours, with MVFR
conditions common at both KCHS and KSAV. Moderate showers should
become widespread by the early afternoon, reducing vis to MVFR
levels. IFR ceilings may arrive from the west during the final
3-4 hours of the 0Z TAFs, I will highlight with a PROB30 along
with moderate showers.
Extended Aviation Outlook: Flight restrictions are likely through
Monday morning as a cold front slowly moves through. Low ceilings
will be the primary issue, though visibility will be reduced at
times in rain.
&&
.MARINE...
Tonight: Onshore flow will continue near shore with winds
veering southeast seaward of the cool shelf waters. Speeds
should continue to be light overnight, less than 15 kt. The main
concerns are swell and perhaps some late night reductions in
vsbys from sea fog or low stratus along the southern GA coast.
We have seen 6 ft swells at Gray Reef this afternoon and expect
similar 5-6 ft heights will persist overnight. We capped seas in
all near shore waters at 4-5 ft in our forecast and maintained
the Small Craft Advisory in GA waters from 20-60 NM offshore.
The potential for sea fog late does not look great as the flow
will struggle to become more southerly, at least through daybreak.
Sunday through Thursday: A cold front will approach from the west
Sunday and cross the waters early Monday. Winds will turn to the
north/northwest following frontal passage as high pressure builds
in. The best cold advection doesn`t set in until later Monday into
Tuesday, so that`s when we have the highest wind speeds. Small Craft
Advisories will be possible. An advisory will be ongoing in the
outer GA waters for persistent elevated seas (6+ ft in the outer
reaches of the marine zone).
The surface high will shift overhead Wednesday and then into the
Atlantic on Thursday with winds and seas expected to subside. No
additional small craft advisories are expected.
&&
.EQUIPMENT...
The KCLX radar remains out of service until further notice.
Adjacent radars include: KLTX, KCAE, KJGX, KVAX and KJAX.
The Downtown Charleston observation site (CHLS1/KCXM) is having
occasional data issues so please use the data with caution.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 11 AM EST Wednesday for AMZ374.
&&
$$
NEAR TERM...NED
SHORT TERM...ECT
LONG TERM...ECT
AVIATION...ECT/NED
MARINE...ECT
EQUIPMENT...
Area Forecast Discussion
National Weather Service State College PA
1028 PM EST Sat Jan 27 2018
.SYNOPSIS...
A weakening cold front will move through overnight and settle
south of the region Sunday. Cooler weather will move in behind
the front to start next week. A weak upper air disturbance will
move through Monday night and Tuesday. A more significant storm
is possible late next week.
&&
.NEAR TERM /THROUGH SUNDAY/...
The light rain is progressing across the region pretty much on
schedule with the weakening cold front entering central PA as of
10PM.
The HRRR shows the rain ending over the NW around or shortly
after midnight, and continuing to taper off from north to south
into the wee hours. There are indications the front will slow as
it moves to the Mid Atlantic coast, possibly causing the rain to
linger into at least mid day Sunday over my far SERN zones.
With the slow infiltration of the cold air, I removed any
mention of a mix or change to snow as precip winds down.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/...
Sunday looks like a great day with nearly full sun over much of
the area. A little light rain may linger over the far SE in the
AM, however conditions will improve as the day continues with
only high clouds expected. The cold air advection will dampen
maximum temperatures tomorrow, however they will still be around
10 degrees above normal.
High pressure moving in from the NW will be interrupted by a
very potent short wave trough rolling over the lower lakes and
srn into Sunday night. So, we may see some cloud cover and
perhaps a flurry in the north, but it should remain dry.
The main forecast trouble in the whole short-term is how much
snow may occur on Monday/night as a much more significant trough
digs to our west and slides overhead on Monday night. GEFS and
SREF plumes are showing only about half the members of each
forecast system generating precip/snow. Likely POPs for the
north look OK, but the lack of moisture is troubling. The trough
does kick up a low off shore. But, the flow over the region is
generally from the N/NW, and that would bring only moisture from
the Great Lakes.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Dry air associated with the surge of cold air arriving on
Tuesday should make it feel pretty cold and blustery. The
thermal trough remains over us for only a day or so, and another
climb up the rollercoaster hill ensues for the second part of
the week.
The next system arrives heading into Groundhog Day and should
bring the risk for mixed precipitation. There is still
uncertainty in the details but there is above average confidence
concerning precip potential late next week given pretty good
model agreement this far in advance.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
Deteriorating flying conditions this evening, as a cold front
and associated rain overspread Pennsylvania from the west. At
00Z the northwest mountains (KBFD) already reporting IFR cigs
and model soundings support a high confidence of continued IFR
cigs there through at least 04Z, with improvement thereafter as
drier air arrives behind front. Initially, a downsloping SSW
flow will keep cigs up at KJST. However, a wind shift to the
west with passage of the front and subsequent upslope flow is
likely to yield IFR/LIFR cigs at KJST after 03Z.
Elsewhere, the lower elevation airfields across the eastern
half of the state appear likely to experience predominantly MVFR
conditions with passage of the front later tonight. Near term
model output suggests arrival of MVFR cigs will occur around 03Z
at KAOO/KUNV/KIPT and around 05Z-06Z at KMDT/KLNS. A core of
strong southwest winds aloft will result in LLWS across eastern
Pa this evening, then relent after midnight, as the strong upper
level winds exit the region.
Cold front and associated band of rain should exit most of
central Pa early Sunday morning. Most places are expected to
return to VFR conditions by 12Z, but rain/cig reductions could
linger until late morning at KLNS. By afternoon, there is a high
confidence of VFR conditions across the entire region, as high
pressure settles over the state.
Outlook...
Mon...PM snow showers/vis reductions western half of Pa.
Tue...AM snow showers/vis reductions possible. Wind gusts
20-25kts from ~330 degrees.
Wed...No sig wx expected.
Thu...Light snow possible western Pa.
&&
.HYDROLOGY...
Hydro concerns continue on Susquehanna River below Marietta
where ice is jammed and water levels are slowly backing up
above the Turkey Hill constriction. A flood advisory was issued
for the area as there is a jam in progress that is causing
minor flooding. The flood watch will continue until early
Sunday evening. Water levels are generally falling on the river
and hopefully the ice jam threat will finally diminish this
weekend. The rain we expected today/tonight should make nary a
dent (bump) in the stream flows.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Sunday evening for PAZ065-066.
&&
$$
SYNOPSIS...La Corte
NEAR TERM...La Corte
SHORT TERM...Dangelo/Ceru
LONG TERM...Steinbugl/Tyburski
AVIATION...Fitzgerald
HYDROLOGY...
Area Forecast Discussion
National Weather Service Green Bay WI
558 PM CST Sat Jan 27 2018
Updated aviation portion for 00Z TAF issuance
.SHORT TERM...Tonight and Sunday
Issued at 247 PM CST Sat Jan 27 2018
The latest RAP analysis and satellite/radar imagery show broad
troughing over the northern Plains to western Great Lakes early
this afternoon. Embedded within this trough are several
shortwaves, one over southern Minnesota and another over southwest
Dakota. Little to no snow showers are being reported with the
southern MN shortwave. However, surface obs are showing widespread
light snow and flurries over northern Minnesota, just ahead of a
cold front positioned just north of the Minnesota-Canadian border.
As this front moves south and interacts with the above mentioned
shortwaves, snow shower chances are the main forecast concern.
Tonight...The weak shortwave trough over southwest Minnesota will
move across central to northeast WI this evening. Progged
soundings are not optimistic about deep saturation associated with
the trough, and upstream obs indicate that chances of flurries or
light snow showers are pretty low. So will just indicate a low
chance of flurries south of route 29. Meanwhile, the arctic front
will slowly shift south across northern WI after midnight. With
widespread flurries/light snow being reported over northern MN,
and winds turning to the northwest off Lake Superior with passage
of the front, think snow chances are looking solid late tonight
across the northwoods, and will increase snow chances. Perhaps a
half inch of accumulations are possible. Lows ranging from the low
teens in the north to low 20s in the south.
Sunday...The front will continue to march south across northern
and central WI. With help from another shortwave moving across
central WI, should see light snow showers and flurries make a push
south into central and east-central WI by late morning to early
afternoon. Kept the highest chances over northern WI though where
there should be some contribution from Lake Superior. Eventually
however, dry air will push south across northern WI by mid to late
afternoon, and should see snow shower/flurry activity gradually
diminish. With plenty of clouds and a colder airmass incoming,
high temps will range from near 20 over Vilas to the upper 20s in
east-central WI.
.LONG TERM...Sunday Night Through Saturday
Issued at 247 PM CST Sat Jan 27 2018
Northwest upper flow is expected for early next week. Wind directions
are not favorable for lake effect snow other than some flurries in
the far north Sunday night through Monday and with dry weather elsewhere.
A clipper system well to our north should bring us some light snow
Tuesday night and early Wednesday, with much colder air to follow
for the end of the week. Wind chills of -20 or colder are possible
in central and northcentral Wisconsin Thursday night and perhaps Friday
night. A winter weather system looks possible Sunday as upper flow becomes
west southwest, and an inverted surface trough sets up from the central
Plains to Wisconsin.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 548 PM CST Sat Jan 27 2018
A weak short-wave trof may bring a few flurries to parts of
central and east central WI this evening, but most of the
precipitation should remain to our south. A cold front over
the Upper Peninsula of MI and far northern WI will sag south
tonight into Sunday morning. This front, combined with another
upper trof, will cause MVFR ceilings and flurries to spread south
across the region overnight into Sunday. Snow showers with MVFR
vsbys are expected over north central WI, where precipitation
will be aided by lake-effect.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......RDM
AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Houston/Galveston TX
917 PM CST Sat Jan 27 2018
.UPDATE...
The cold front that has slowly worked its way across SE TX today
is currently draped across Jackson, Harris, and Liberty counties.
Most of the showers have dissipated behind the front, while
showers still remain over the nearshore and offshore waters as of
850 PM. A stalled boundary situated in the northeastern Gulf of
Mexico is acting to provide surface convergence, while also
overlapping with the best moisture available with dewpoints in
the 70s. Therefore showers have continued to develop along this
boundary, which should continue to shift southeast of the offshore
waters through the overnight period.
A few changes were made to the forecast in tonight`s update. Both
the HRRR and SREF peg the coastal counties, bays, and nearshore
waters for the possibility of patchy fog. Although the cold front
should continue to slowly push southeastward and eventually
offshore by Sunday morning, went ahead and added the chance for
patchy fog through the early morning hours before the winds get a
chance to swing out of the north. Cloud cover will also play a
factor this evening, as short term guidance has slowed the
clearing line behind the front. The low level broken to overcast
cloud deck that is in place should help to regulate temperatures
overnight. Therefore, decided to warm overnight low temperatures
keeping them in the low to upper 50s. Clear skies are not expected
to prevail at the coast until late afternoon to early evening
Sunday. This should not allow for too much of a diurnal swing
Sunday, allowing high temperatures to possibly warm into the low
to mid 60s. As skies clear and the cold air advection pattern
really gets underway, temperatures and dewpoints will quickly
fall as northerly winds continue to advect in a colder and drier
airmass late Sunday.
Hathaway
&&
.PREV DISCUSSION /Issued 538 PM CST Sat Jan 27 2018/...
.AVIATION...
Dreary day across the area, though the bulk of rain has moved
offshore. A smaller area of rain exists near the coast, and
mentions for that remain for coastal sites. Indeed, a couple
convective cores have me leaving TS mentions at LBX just to be
safe. Scattered light showers exists farther inland, prompting
the VCSH mentions for all but CLL, which appears to be done.
Beyond the rain, low ceilings and patchy fog continues, and IFR or
worse conditions can be expected through the night and into
Sunday. As we`ve seen late this afternoon, we`ll probably see
temporary breaks in the low clouds early in the period, but
expecting those to fill in quickly this evening and not even
confident enough for a TEMPO at this time. Am more optimistic
than the guidance as far as fog goes - suspect the wind will be
up enough at sites the models hit hard with fog to keep visibility
from really crashing. Indeed, webcams around Galveston Bay are at
or near the best they`ve been all day. Not that it matters, as
ceilings will keep flight categories down anyway.
We should see slow improvement through the afternoon to
MVFR, but lingering low moisture will keep the full post-frontal
clearing delayed until late afternoon up north and beyond the end
of the forecast period near the coast. Eventually we`ll get to
something like SCT250, but it will take some time.
Luchs
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 54 64 40 64 35 / 20 0 0 0 0
Houston (IAH) 59 64 42 63 38 / 30 0 0 0 0
Galveston (GLS) 58 61 46 60 44 / 40 10 0 0 0
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Dense Fog Advisory until 4 AM CST Sunday 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 SHOULD EXERCISE CAUTION until 6 AM CST Sunday 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.
&&
$$
UPDATE...08
AVIATION...25
Area Forecast Discussion
National Weather Service Wilmington OH
1035 PM EST Sat Jan 27 2018
.SYNOPSIS...
Rain will continue to end as a cold front moves through the
area and weak high pressure builds in from the west. An upper
level disturbance along with another cold front will bring
cooler temperatures and a chance for some light snow on Monday.
&&
.NEAR TERM /THROUGH SUNDAY/...
Surface cold front evident on radar/sfc observations moving
though south central Ohio and northeast KY. This front will
clear ILN/s FA with rain coming to an end around midnight.
A period of a couple of hours of post frontal clouds will be
followed by clearing as weak surface high pressure builds into
the area overnight.
Clear skies, light winds and moist ground will lead to the
development of fog. Question revolves around how dense the fog
becomes overnight. Latest RAP forecast soundings show very shallow
low level moisture. Have added mention of fog in the forecast
and issued SPS for locally dense fog and updated HWO product.
With drier air advecting into the region uncertainty exists
on potential dense fog and coverage. This will have to be
watched for the potential for a dense fog advisory.
Lows tonight will range from the upper 20s in the northwest to
the mid and upper 30s across the southeast.
&&
.SHORT TERM /SUNDAY NIGHT/...
A weak axis of surface high pressure will be situated
southwest to northeast across the region by early Sunday
morning. This will slowly weaken through the day as mid level
short wave energy approaches from the west Sunday afternoon into
Sunday night. The airmass will remain relatively dry through
the day on Sunday but then gradually begin to moisten up from
the west Sunday night. This will lead to an increase in clouds
Sunday night and a chance for a few snow showers late. Highs on
Sunday will be mostly in the mid 40s with lows Sunday night
falling into the upper 20s.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Period starts with an upper trough approaching from the west. Ample
lift generated by a mid level short wave combined with limited
moisture will produce light snow Monday, with a few tenths of an
inch accumulation indicated. Trended toward drier model blend that
is lower than moister ECMWF which produces around an inch.
Dry and cold weather is expected Tuesday under 1031mb surface high
pressure. Breezy and milder conditions are forecast for Wednesday as
the high travels east, leaving the Ohio Valley in a southerly flow.
For Thursday, current models suggest that snow developing along a
cold front near the Ohio River may result in higher snowfall amounts
in southern counties. Position, timing and intensity of this event
will be further resolved by later model runs. Cold and drier weather
will follow for Friday and Saturday with high pressure centered to
the south.
Highs in the near normal 30s are forecast for Monday, before
readings slip to around 30 on Tuesday. A recovery to the low 40s is
expected Wednesday under sunshine and warm advection. Reading will
drop to the 30s Thursday, then down to the 20s Friday and Saturday
in response to cold advection associated with the front.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Surface cold front pushing across ILN/s FA. Widespread rain
along and ahead of this front is coming to an end across all TAF
sites. MVFR CIGS with a brief period of IFR will be observed
this evening. Weak surface high pressure will build into the
region by morning. Skies will clear and with winds becoming
light and lingering moisture for will likely develop. Have
MVFR to possibly IFR vsbys restrictions developing overnight due
to this fog. Fog will improve Sunday morning with VFR conditions
returning.
OUTLOOK...MVFR ceilings and MVFR/IFR visibilities possible on
Monday and again on Thursday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...JGL
NEAR TERM...AR
SHORT TERM...JGL
LONG TERM...Coniglio
AVIATION...AR
Area Forecast Discussion
National Weather Service Blacksburg VA
629 PM EST Sat Jan 27 2018
.SYNOPSIS...
A cold front will move into the mountains tonight, before
pushing east of the region late Sunday afternoon. An Arctic
front will cross the area Monday, with any lingering moisture
changing over to snow showers and flurries. Cold high pressure
builds in with drier weather for the middle of next week.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 600 PM EST Saturday...
Lowered PoPs this evening based on latest HRRR and current
radar trends. Light rain to spread across the VA-NC border
counties between 7p-9p. Showers associated with the front will
enter the far west (SW VA-SE WV) around 10p then move eastward
through Sunday morning. Increased PoPs after midnight to 100
percent as a good soaking of rain (0.25-0.50 of an inch) is
likely.
As of 230 PM EST Saturday...
Split flow regime as depicted by a cold front to the west and low
pressure along the Gulf coast will gradually come more into
phase by Sunday making for widespread rainfall later tonight
through the end of the weekend. Models have again slowed up
given an initial slower cold frontal arrival into Sunday morning
per parallel southwest flow, and following added digging of
another shortwave into the dominant northern stream trough to
our west on Sunday. This should help to hold best lift over the
region Sunday as these separate pieces of energy come in line
along/east of the mountains. However heaviest rainfall looks to
remain to the south and east where more convection may mix in
and moisture/theta-e will be best. Thus have slowed up
widespread pops some this evening with most light rain along the
Blue Ridge early on, before showers expand across the south
along the southern jet, and over the northwest ahead of the
front espcly after midnight. Should see these areas basically
merge overnight and then linger in periodic fashion Sunday as
weak added waves slide up the boundary which may take until late
Sunday to clear the east.
Forecast QPF perhaps a bit more given a slower solution with
possibly a half to three quarters of an inch overall, except
locally better than an inch through Sunday along the southern
Blue Ridge, and less central sections between the merging
systems. Otherwise temps warm enough for all liquid with lows in
the 40s this evening before perhaps rising some late just ahead
of the front. Continued southwest low level flow for much of
Sunday before the front crosses supports highs mostly 50s Blue
Ridge east and around 50 west.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 345 PM EST Saturday...
Waves along the front will continue to slow the progression of the
boundary and expect lingering synoptic to couple with sufficient low
level moisture to allow for a gradual west/east decrease in POPs Sunday
night, but expect rain showers will keep going east of the Blue Ridge
through Monday morning before winding down. Some colder air will seep
in from the west and may result in some wet snow with minimal
accumulation late Sunday night through Monday at the higher elevations
west of the Blue Ridge.
The arrival of much colder air will be delayed by the slow movement of
the frontal boundary and expect the arctic front will not surge through
until early Monday night, accompanied by another round of
precipitation in the form of snow showers. The best period for
accumulation snow in upslope snow showers west of the Ridge will be
overnight Monday night into Tuesday when a couple inches of
accumulation is expected a the higher elevations. However, synoptic
support is quite good as vigorous short wave energy will be rotating
through the region and combined with steep lapse rates expect show
showers with some light accumulation to extend further east and past
the Ridge into the piedmont late Monday night into Tuesday morning,
which may affect the Tuesday morning commute. Snow showers will
gradually wind down to lingering flurries west of the Ridge by Tuesday
evening as a large area of high pressure settles over the region
Tuesday night.
Winds on Tuesday will be quite blustery as the low level wind field
amplifies and a well mixed boundary layer allows for good downward
momentum transfer. At this time it does not look like winds will meet
advisory criteria but we can expect gusts of 30MPH to 40MPH. These
winds will combine with the cold temperatures in the advancing arctic
airmass to create single digit wind chill values west of the Blue
Ridge by late Tuesday afternoon.
Temperatures will be taking a tumble through the first part of next
week with readings expected to be well below normal.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 345 PM EST Saturday...
The progressive upper pattern will allow for a brief break in the
action through midweek with a trend for temperatures retuning at or
above normal levels by Thursday. The next frontal system will then
begin to affect the region Thursday night through Friday. There will be
a good amount of precipitation with the front and early indications
are that cold air moving in on the backside of the system may be quick
enough to couple with the moisture and generate another round of wintry
precipitation Friday night.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 605 PM EST Saturday...
Should see a gradual deterioration in cigs this later this
evening as low level moisture expands northeast along the Blue
Ridge and deeper moisture ahead of a cold front to the west
approaches. However not expecting all locations to drop to sub-
VFR until around midnight with a slow increase in showers after
05Z/12AM.
Will then see more widespread showers spread across the region
from the south and west overnight with rainfall including poor
flying conditions lingering through much of Sunday. This will
include MVFR/IFR or worse cigs and MVFR to ocnl IFR vsbys in
rain/fog espcly after midnight through Sunday. Winds should be
light and mainly southerly below 10 kts through the weekend.
Extended Discussion...
VFR weather will generally return to east of the Blue Ridge
Monday with perhaps a period of MVFR Monday night within a band
of light precipitation along the arctic front. Lingering
upslope northwest flow in the mountains brings more MVFR/IFR
clouds and scattered to numerous snow showers Monday into
Tuesday. VFR then returns to all sites mid- week as high
pressure builds in from the west.
Another weather system will approach the area late in the week
with the potential for rain and/or winter precipitation and
widespread sub-VFR ceilings by Friday.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...JH
NEAR TERM...JH/RCS
SHORT TERM...MBS
LONG TERM...MBS
AVIATION...JH/RCS