Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/31/22
Area Forecast Discussion
National Weather Service Burlington VT
946 PM EST Sun Jan 30 2022
.SYNOPSIS...
A weak boundary will produce scattered snow showers across northern
New York into Vermont late tonight into Monday afternoon. Snowfall
accumulations will be a dusting to 2 inches in the most persistent
snow shower activity, mainly over northern New York. Temperatures
will be cool tonight, but warm to seasonable levels on Monday and
Tuesday, with above normal values for Wednesday into Thursday. A
widespread precipitation event is expected for late week.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
As of 941 PM EST Sunday...As expected, the rate of cooling has
been a smorgasbord of trends between clouds and light south to
southwest winds or clear skies. Even in clear skies, some spots
are radiating efficiently, while other areas have struggled to
sink. Massaged the hourly temperatures as best as possible.
Otherwise, the area of light lake effect has developed as
anticipated. Webcams across Edwards, Tupper Lake, and Saranac
Lake in New York are showing this light activity. Thus, the
forecast is on track. Have a great night!
Previous Discussion...
Water vapor shows mid/upper lvl trof acrs the ne conus with
several weak embedded 5h vorts. First weak s/w is approaching
the Ottawa Valley this aftn, with secondary vort located btwn
Hudson Bay and the northern Great Lakes. These disturbances in
the jet stream winds aloft wl interact with a weak sfc boundary
to produce periods of light snow shower activity acrs northern
NY into the mtns of northern VT late tonight into Monday. In
addition, cloud layer flow of 15 to 25 knots from the southwest
ahead of approaching boundary wl help in advection of slightly
deeper Lake Ontario moisture into our northern NY zones
overnight into Monday. Have noted the NAM3KM/NAM12KM RAP and
HRRR all support this general idea of light snow showers
developing aft 06z and prevailing at times thru 21z Monday.
Soundings indicate depth of moisture is only thru 10kft or
700mb, but highlights RH>80% thru the favorable snow growth with
some weak instability present. Have continued with chc pops for
now, but could see some likely pops from northern NY into the
mtns of northern VT, on Monday. Precip amounts wl be <0.10 but
given some fluff factor an inch or two of snow is possible in
the most persistent snow shower activity. Have noted several
high resolution runs of the BTV4km and RAP13 highlight enhanced
llvl convergence and associated slightly higher qpf values of a
few hundredths acrs the northern CPV on Monday aftn, as boundary
sags south, so potential for an inch of snow is possible at
BTV/PBG and Highgate. Outside of the snow shower activity very
quiet with main concern temps tonight into Monday. Thinking lows
ranging from -10 to -15F NEK to +5F parts of the CPV/SLV. Of
course if skies stay clear and winds decouple for several hours
this evening, lows could be much lower, but feel winds wl change
to the south/southwest and clouds increase helping limit the
free fall tonight. Monday highs generally in the upper teens to
mid 20s and should feel nice given our recent very cold spell.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
As of 322 PM EST Sunday...High pressure will remain in control of our
weather Tuesday and Tuesday night with dry conditions expected.
Should see plenty of sunshine Tuesday with daytime temperatures
moderating into the upper 20s to lower 30s for highs on Tuesday, and
generally holding in the mid 20s Tuesday night (except teens in the
Adirondacks and far nern VT). Should see our first high temperature
at or above freezing since January 20th at BTV. As the center of the
1040mb surface high drifts ewd into the Canadian Maritimes, a
southerly return flow will set up across the North Country with an
increasing pressure gradient. Surface winds generally S-SE 10-15 mph
by Tuesday afternoon, and then increasing Tuesday night to 10-20
mph, and locally 15-25 mph in the Champlain Valley with gusts to 35
mph near Lake Champlain.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 322 PM EST Sunday...Potential heavy frozen precipitation event
remains the primary focus of the long-term period, with the
potential for moderate to heavy snow and/or mixed wintry
precipitation Thursday thru Friday AM based on 12Z NWP model suite
and relatively good run-to-run consistency thus far.
Wx conditions begin seasonable mild, as strong surface ridge drifts
east of Nova Scotia and upstream frontal boundary remains across
sern Ontario into the Ohio Valley. Despite some increasing mid-upper
level clouds from the west, Wednesday should be our warmest day of
the week with continued south winds and high temperatures reaching
the upper 30s to around 40F. The frontal zone gradually pushes sewd
across northern NY Wednesday night, and should push into southern VT
during the early morning hours Thursday. This will allow colder air
to gradually filter in at low levels, with the potential for some
intermittent light rain changing over to a wintry mix or snow across
the north by early AM Thursday. Have indicated 70-90% PoPs by 12Z
Thursday associated with the initial frontal convergence and
frontogenesis. There may be some winter travel impacts for the AM
commute Thursday as the sub-freezing air filters in on N-NW flow. We
may have some continued light/steady precipitation throughout
Thursday driven by continued frontogenesis forcing extending from
WSW-ENE somewhere across our region.
Question then becomes whether the strong 925-850mb frontal zone
stalls across our region, or if it gradually settles off to our
south ahead of the main shortwave trough. The mid-level flow is
parallel to the frontal zone, and a vigorous shortwave trough is
expected to translate newd from the lower Mississippi River Valley
later Thursday. This feature is associated with significant moisture
advection from the Gulf of Mexico. Potential for PW values of 0.6-
0.75" across the southern half of our forecast area Thursday night.
If 850mb frontal zone can become quasi-stationary, as currently
indicated by the 12Z GFS, 12Z Canadian, and 12Z ECMWF, should see a
period of strong frontogenetic forcing and potential for heavy
snowfall Thursday evening through Thursday night somewhere across
our CWA, likely ending Friday morning as best QG forcing shifts to
our east. Relatively long duration event possible, and impressive
QPF signatures with 12Z GFS indicating an axis of 1-1.25" liquid
equivalent precipitation across central and southern VT. The 12Z
GEFS mean QPF and 12Z operational ECMWF are similar, so we are
seeing good consistency at this point. PoPs late Thursday and
Thursday night generally 70-90%, which is high for a Day 4-5
forecast. Best potential for possible sleet and freezing rain based
on current indications would be across s-central VT, but it`s early
at this point to be confident in the thermal profiles. One concern
is that the strength of the surface anticyclone across Quebec
(1042mb per 12z GFS) may favor displacing the frontal zone further
south, and perhaps the axis of heaviest precipitation further south
than currently shown. Still 100-120hrs from the event, so we`ll
continue to refine as the details become more apparent. Those with
travel plans Thursday into early Friday should carefully monitor the
latest forecasts.
Weather returns cold and quiet for next weekend. With clearing
Friday night, below zero low temperatures are likely, with highs
only in the teens for Saturday and lower 20s for Sunday.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Through 00Z Tuesday...VFR conditions prevailing, with west winds
trending towards calm to variable and terrain-driven. Periods of
light, lake effect snow showers will be possible across KMSS and
KSLK from about 04Z to 16Z. These may only drop visibilities to
about 4 SM and ceilings perhaps just under 3000 ft agl. A weak
trough will shift east about 16Z, and gradually taper off snow
across KMSS and KSLK, with snow showers shifting towards KPBG
and KBTV. Will wait to see how expansive coverage is before
noting impacts to aviation conditions, and have VCSH for now,
expected from about 20Z Monday through 03Z Tuesday. Winds
becoming south ahead of trough feature by 15Z, around 5 knots.
Activity will likely to dissipate, and not impact other
terminals while winds briefly shift west, before becoming light
and variable beyond 00Z Tuesday.
Outlook...
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. NO SIG WX.
Tuesday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Wednesday: Mainly VFR, with local MVFR possible. Slight chance
SHRA.
Wednesday Night: MVFR/IFR conditions possible. Likely SN, Chance
RA.
Thursday: Mainly MVFR, with areas IFR possible. Definite SN,
Definite RA.
Thursday Night: Mainly MVFR and IFR, with local VFR possible.
Definite SN.
Friday: MVFR. Chance SN.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Taber
NEAR TERM...Haynes/Taber
SHORT TERM...Banacos
LONG TERM...Banacos
AVIATION...Haynes/Taber
Area Forecast Discussion
National Weather Service Cleveland OH
938 PM EST Sun Jan 30 2022
.SYNOPSIS...
A ridge of high pressure will build into the Ohio Valley late
tonight and influence the region through Monday night as it
slowly moves into New England. A warm front will lift across the
region Tuesday followed by a strong cold front Wednesday. This
front will stall over the Ohio Valley and act as a focus for a
potent low pressure system tracking out of the southern Plains
late Wednesday through Thursday.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
Areas of haze are being reported at various sites across the
area this evening. This is due to a surface inversion becoming
established, trapping moisture near the surface. This will
result in visibilities reduced to 3-5 SM, although locally lower
is possible.
Previous Discussion...
A band of light snow or flurries has remained persistent across Lake
Erie into far NE Ohio and NW PA this afternoon. The axis of the main
mid/upper shortwave trough associated with the clipper is crossing
northern Ohio as of mid afternoon based on latest water vapor loops
and RAP analysis. The weak 1012 mb surface low is currently moving
into West Virginia while the 850 mb low is crossing central Ohio.
There appears to be a wing of weak warm air advection and very weak
isentropic ascent to the N and NE of the 850 mb low, and this is
likely driving this persistent snow band. The good news is that RAP
BUFKIT forecast soundings are showing that the best Omega within the
5-10 thousand foot DGZ has already moved out, and only moisture
remains within the DGZ. This is leading to little to no additional
accumulation within this band of persistent light snow because the
lack of lift is causing very fine snow flakes or flurries. Forecast
soundings show the remaining moisture within the DGZ rapidly exiting
between now and 00Z. With all of this in mind, held onto PoPs
slightly longer the rest of this afternoon in NE and east central
Ohio, but limited additional accumulations to a trace to 0.2 inches.
The snow is still on track to end in both eastern Ohio and NW PA by
00Z as the system moves E/SE of the region.
Behind the exiting clipper, a strong 1022 mb surface high will build
into the western Great Lakes and Upper Mississippi Valley tonight
and reach the Ohio Valley by Monday morning. At the same time,
another mid/upper shortwave trough will drop through the deep NW
flow aloft and cross the region late tonight through Monday morning.
The aforementioned surface high will bring a large amount of dry air
and subsidence, so the shortwave will come through dry. Forecast
soundings show an increase in moisture in the 10 to 20 thousand foot
layer late tonight into Monday morning while the low-levels remain
dry, so this will just result in keeping cloudy skies in place as
the wave passes. Removed the mention of fog from the previous
forecast tonight since any clearing early in the night will quickly
fill back in with clouds. Some lift ahead of the shortwave will
generate a weak band of lake-effect snow, but a land breeze and
overall WSW flow will keep this over the lake and into the Buffalo
area. Lows tonight will stay up a bit due to the cloud cover with
upper single digits to low teens (coldest in far eastern Ohio and NW
PA).
The shortwave trough will quickly exit Monday morning with mid/upper
shortwave ridging building in from the west through the day. This
combined with the surface high moving toward the NE CONUS will set
up return light SE flow resulting in a rise in temps. We should
finally reach the low 30s in many areas Monday afternoon along with
increasing sunshine during the afternoon as the aforementioned
shortwave ridge builds in. This will feel nice after the recent
cold! The surface high remaining over New England and shortwave
ridge overhead will maintain fair and milder weather Monday night
with lows in the upper teens to low 20s as warm advection continues
to increase ahead of a major mid-week storm. See the short term
section for details on that.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Main focus today continues to be a long-duration, potentially high
impact storm with all precipitation types and various impacts
possible Wednesday through Thursday or Thursday night. Trend to back
off on the arrival of rain Tuesday into Tuesday night continues.
Basically have a dry forecast for Tuesday now, though west of I-75
may still get close. With highs in the 40s, if you have some pesky
snow or ice around the outside your home or business to take care
of, Tuesday is your day to do it. Timing the initial arrival of rain
Tuesday night ahead of the approaching cold has trended a bit slower
the last couple of cycles as ridging pumps up on the East Coast,
though it should spread into northwest Ohio and at least into the
western and central lakeshore by Wednesday morning...but may not get
farther than that. The bulk of precip through dawn Wednesday will be
rain area-wide, though the Toledo area and points west may get close
to starting to mix with / change to snow by then. Temperatures over
parts of Northeast OH and into PA may be near freezing if rain
arrives early enough on Wednesday, so will have to watch for a brief
mix with sleet or freezing rain at the onset there...but should be
fairly brief if it occurs at all.
While details are still murky and caution is advised in terms of
viewing and sharing "bonkers" snow and ice accumulation outputs from
some models at this range from a messaging standpoint, there`s been
enough consistency in the general evolution the last couple of days
to start sketching out a general conceptual idea of the evolution
and potential impacts and adjust / fine tune from there.
Here is the rough conceptual idea at the moment:
A cold front will gradually work northwest to southeast across our
area Wednesday and Wednesday night. A wave of moisture streaming
along the front will cause precipitation (mainly rain) to break out
Tuesday night into Wednesday, with a wave of low pressure along the
front causing the heaviest precipitation to occur Thursday into
Thursday night. Rain will gradually transition to snow behind the
front starting Wednesday in northwestern Ohio, though this
transition may take more than 24 hours to work across our forecast
area, with concern for a zone of wintry mix persisting if the
transition zone gets "hung up" across our region.
Key takeaways and uncertainties:
1) An initial round of light to moderate precipitation is expected
late Tuesday night / Wednesday into Wednesday night across the
region. There may be a relative lull (but unlikely to be a complete
break) late Wednesday night before the heaviest precipitation of the
event occurs Thursday into Thursday evening. Synoptic precipitation
exits Thursday night into Friday leaving a bit of lake effect.
2) Rain will gradually begin to change to snow from northwest Ohio
east into the lakeshore counties Wednesday into Wednesday evening.
There may be some brief sleet with this initial transition, but it
doesn`t look significant. There is still some uncertainty in how
quickly this transition occurs, especially outside of northwest
Ohio. This may have implications on the Wednesday evening commute
along the lakeshore in the rest of Ohio, including Cleveland. A
slower transition would mean just a cold rain during the commute
Wednesday evening in Cleveland.
3) The cold front will slowly move south across the rest of our area
Wednesday night into Thursday morning, with surface temperatures
dropping below freezing north of the front as it progresses. How
quickly this front progresses is still uncertain, which will impact
when places like Mansfield, Akron/Canton, and Youngstown points
south change from rain to "something wintry" Wednesday night into
early Thursday.
4) The greatest concern for a swath of wintry mixed precipitation is
later Wednesday night into Thursday. Confidence is growing in
Northwest Ohio remaining mainly snow in this timeframe. Confidence
is also moderate to high that places like Canton to Youngstown won`t
change to all snow until later Thursday or Thursday night, meaning
precipitation will either be rain or a wintry mix (depending on the
surface temperatures) through a good chunk of Thursday. Places in
between, such as Mansfield, Akron, Ravenna and Meadville are likely
to see temperatures fall below freezing between Wednesday evening
and early Thursday, and may see either mixed precipitation or snow
in this timeframe depending on the exact track of the low. The
lakeshore is favored to be mainly snow in this timeframe, but we`ve
seen mixing work farther north than expected before so that will be
a tricky aspect we watch for as we hone in.
5) Colder air rushes in aloft later Thursday into Thursday night,
which will change any lingering wintry mix or rain over our
southeastern counties to snow before the system exits Thursday night
or early Friday. The drop in temperatures will cause any snow,
slush, or ice on the ground and roadways after the storm to freeze
into a solid block of ice that won`t be going anywhere next weekend.
6) A widespread 1.25 - 2.50" of QPF is likely across our entire area
for the duration of the event. Where the bulk of this QPF falls as
snow accumulations will be significant. Where more of this QPF falls
as rain or perhaps freezing rain, we need to continue to monitor for
hydrological concerns. Of particular concern is the Canton to
Youngstown area, where a larger portion of the precip will likely
fall as "not snow" and where 2" or more of water is held in the snow
pack. Frozen rivers may contribute to ice jam problems as some
melting occurs, and the frozen ground will cause any rain / snowmelt
to immediately run off. Both factors may cause a concern for river
flooding on the "rainy side" of the storm. A narrow zone of
problematic sleet or freezing rain accumulations may occur late
Wednesday night into Thursday given the amount of QPF forecasted if
a zone of wintry mix develops and stalls for a period of time.
Meteorological comments:
The overall evolution remains similar to the last couple days with
an initial wave of overrunning causing a round of light to moderate
precipitation Wednesday into Wednesday night. This will be followed
by a larger piece of the trough ejecting out of the west and
sparking a wave of low pressure that moves across the Ohio or
Tennessee Valley Thursday into Thursday night, bringing the heaviest
precip of the event. Models show a period of 50+ knots of flow up a
very steep 300K isentropic surface on Thursday across the area, with
the region under the right-entrance quadrant of a 150+ knot jet
streak. With PWATs of over 1" over the Ohio Valley flowing into all
of this lift, moderate to heavy precip rates are looking likely
Thursday into Thursday evening. With soundings showing near-neutral
lapse rates in the mid-levels for a time on Thursday amidst the
outstanding lift, slantwise convection may occur and help focus
bands of heavy snow where it`s cold enough for snow to fall in this
timeframe. Have high confidence in 1.25-2.50" of QPF from this event
across our entire area at the moment given the prolonged nature,
good jet support, anomalously high moisture advecting into the Ohio
Valley from the Gulf / Caribbean and period of strong lift Thursday.
Will watch trends in the track and evolution for changes to the
QPF...am not quite ready to go all-in on the GFS 3.00"+ of QPF yet,
that`s almost un-heard-of for a winter storm around here.
Feel that today`s runs of the 12z GFS, 12z European, and 0z Canadian
models are a good place to start for a conceptual model of how this
event plays out (though would not focus on exact amounts any model
is spitting out yet, and expect some tweaks to the track still).
There was a modest eastward bump in the track of this system Friday
into Saturday, due to greater influence from the polar vortex near
Hudson Bay and a trend to eject the trough out of the west a bit
slower. However, today`s model and ensemble runs have halted that
trend. We will still have to watch the overall synoptic evolution
for trends as we`re still 3-4 days out from the bulk of this storm
occurring...a relative eternity for a tricky meteorological
forecast. Overall gut feeling with a strong ridge over the eastern
US and trough over the west is that the more amplified solution is
favored, but the set-up is still sensitive to how organized the
trough coming out of the west is and how much the polar vortex to
our north presses down on the situation. There are enough ensemble
members with a more suppressed solution (which would yield more snow
area-wide, but somewhat less QPF overall) to not rule out a trend
that way yet, though the current lean is against adjustments in that
direction.
The initial transition from rain to snow Wednesday into Wednesday
evening looks fairly clean, with forecast soundings not showing much
of an elevated warm nose in that timeframe. Where the concern for a
wintry mix increases is late Wednesday night into Thursday, as the
approaching frontal wave increases warm air advection aloft while
the surface boundary continues to inch south due to Arctic air
seeping in from the north. Most deterministic solutions have
depicted a zone of significant wintry mix somewhere in the region
over the last few days, and feel that`s a legitimate concern unless
the whole thing trends much flatter and colder. Have introduced a
mix from late Wednesday night through Thursday evening in the grids
today...a rough first pass for now, expect fine tuning. Mixing finds
a way to inch farther north than expected in these kinds of systems,
which could be a key factor in figuring out eventual accumulations
in the Cleveland area.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
Lingering light synoptic snow may linger into Friday over the south
and east...models not in agreement on when it completely exits yet.
Some lake effect likely follows into Friday night before the ridge
moves overhead. High pressure will keep Saturday dry, with a weak
system possibly approaching on Sunday (no POPs yet). Big story
Friday into the weekend will be the cold again, with sub-zero
overnight lows possible (especially where fresh snowfall occurs) and
highs in the 10s to lower 20s.
&&
.AVIATION /00Z Monday THROUGH Friday/...
Snow showers have finally moved out of the area, but mostly
cloudy skies are expected to continue through the TAF period.
VFR conditions will persist for KTOL, KFDY, and KERI, but the
remaining terminals may drop down to MVFR visibilities between
8Z-15Z. Models are suggesting that a strong surface inversion
will develop and trap moisture in the lowest levels. Conditions
are not favorable for dense fog, but lower ceilings and
visibilites near 4SM are possible. Winds overnight will be
light and variable, inhibiting any mixing of the moisture.
Ceilings will be more gradual to improve, but once winds begin
to increase from the southeast to 5-10 knots on Monday, all
terminals should return to VFR conditions. Timing of this
improvement remain uncertain for the far eastern terminals, but
will continue to monitor the progression of the high pressure
and increase in winds.
Outlook...Non-VFR conditions are likely in widespread rain
and/or snow Tuesday night through at least Friday morning.
&&
.MARINE...
Gusty southerly winds develop on the lake Tuesday and Tuesday night
ahead of an approaching cold front. Winds turn north-northeast
Wednesday and Thursday behind this front, and gale-force winds can`t
be ruled out if the storm causing these winds ends up on the
stronger side. Expect ice to shift quite a bit with all of the wind
through this week.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...Garuckas
NEAR TERM...Campbell/Garuckas
SHORT TERM...Sullivan
LONG TERM...Sullivan
AVIATION...Campbell
MARINE...Sullivan
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
611 PM CST Sun Jan 30 2022
.AVIATION...
Currently we have VFR conditions across the region, waiting on a
vigorous upper low over NM to makes its way to the SE. With the
system`s approach overnight, low level flow will increase out of the
south with some 20-30 kt of S wind expected in the lowest 850 MB.
Isentropic analysis shows good overrunning will take place
especially after 06z with a gradual moistening of the lowest levels.
Expect some low clouds to start showing up on satellite and
observations shortly after midnight with guidance from most models
showing IFR conditions expected at all sites by or around 12Z.
Precip will likely hit DRT first and then shift east toward
SAT/SSF/AUS by the early morning hours. Have prevailing -RA or RA
through most of the morning with a rain chances going down from west
to east across the region by the late afternoon. Could be some SHRA
in there, but any TS will likely be east of the AUS/SAT/SSF sites. DRT
precip will end in the early morning but clouds wont clear until
afternoon. SAT/SSF could start to see improvements by mid-late
afternoon Monday...with AUS hanging onto IFR and RA until early
evening past 00z as the system will be slow mover.
Winds will be tricky because various models show slightly different
tracks of the surface low. If it stays north of AUS, then most sites
will keep with NE winds tomorrow. The consensus was somewhere between
SAT and AUS...keeping SAT/SSF/DRT mainly with S winds until it
passes by in the afternoon with a NW shift in the PM hours. AUS
should be somewhere at a NE wind in the AM, becoming E, then backing
to a NE wind again late in the day. Speeds look to be 10kt or less.
A farther look into Monday night shows clearing out in DRT, but
AUS/SSF/SAT at least with some MVFR ceilings and maybe some fog if
partial clearing does occur somewhere and the ground remains wet from
the expected Monday rainfall.
.PREV DISCUSSION... /ISSUED 317 PM CST Sun Jan 30 2022/
SHORT TERM (Tonight through Monday Night)...
Temperatures are in the 60s for most locations this afternoon under
plenty of sunshine. With mostly clear skies and dewpoints in the 30s
and 40s across the area, one would not expect for widespread
beneficial rainfall for much of the area beginning late tonight.
However, things will quickly change overnight as a strong closed low
begins to impact the region. The center of the low is currently
entering southern New Mexico and will move into West Texas after
midnight. As it does, widespread forcing for ascent will overspread
South-Central Texas. The lift will also be aided by the associated
upper level jet streak entering the region at the same time, placing
the area in a favorable region for upward motions as well. Ahead of
the system this evening and tonight, southerly flow at 850 mb around
20-25 knots will increase moisture in the lower levels of the
atmosphere, leading to PW values in our eastern counties up to 1.35
inches by tomorrow afternoon. All of these ingredients signal a
decent rainfall event for most of the area, outside of the
western/southwestern CWA, where moisture values do not have time to
increase ahead of the best lift.
High-res models show the rain initially developing over the Edwards
Plateau region after midnight with more isolated to scattered
activity across the eastern area. The more substantial rain out west
will move eastward into the Hill Country by 3-4 AM, into the I35
corridor around 6 AM and into the eastern counties by 8 AM. Rainfall
will end from west to east by late Monday evening. The upper low
will not be moving too fast and with PW values well above
climatological normals, rainfall amounts could pile up mainly along
and east of the I35 corridor where that better moisture is expected.
Some of the latest guidance from the high-res models has really
increased the progged rainfall totals. The HREF mean is approaching
4 inches with some isolated 6+ inch totals in the max QPF field
across the eastern counties. The 12z HRRR and FV3 and ARW also show
some similar totals. The global models show totals to be more in the
1-3" range with some isolated higher totals. For the official
forecast, have bumped up rainfall totals for areas mainly east of
the I35 corridor to show the 2-4 inch areal average totals. Because
of this, have increased wording in the Hazardous Weather Outlook and
other messaging to mention localized flooding where the higher
totals occur. The dry soils from recent weeks should soak up most of
this rainfall to alleviate any widespread flooding concerns, but we
will continue to monitor for any further increase to the potential
flooding messaging through tomorrow.
In addition to the potential for heavy rainfall, afternoon CAPE
values in the southeast CWA will approach 750 J/kg and with some
decent mid-level lapse rates and weak effective shear a strong storm
could be possible, but overall chances for severe storms is pretty
low. Lows tonight and tomorrow night will be in the 40s and 50s with
highs tomorrow near 60 where rain is expected for much of the day
and will range up to the lower 70s in the west.
LONG TERM (Tuesday through Sunday)...
Daytime Tuesday begins with most areas seeing a light and variable or
light northeast breeze and some wrap-around moisture possibly
holding the clouds and perhaps some patchy fog in place. With clouds
to decrease by midday and a zonal flow pattern aloft over TX, we
should get a good day of warming with highs in the 70s almost area-
wide.
An amplifying pattern upstream brings a quick return of overnight
cloudiness over the area Tuesday night, and then a dramatic weather
change by late Wednesday when an arctic front arrives. Wednesday
afternoon should see a partial fropa into the Hill Country to leave
us with a good sized Max T gradient from north to south. We trended
warmer with these maxes as the 12Z deterministic runs deepened the
upstream trough to signal a stronger and slower moving upper low.
This will also translate to the overnight temperatures to reverse
slightly, the cooler trend that was noted for the 00Z forecast
cycle. Another shifting trend is that QPF output continues to grow
for the first 18 hours behind the front, and that could further slow
down the rate of cooling at least before the very cold dew point
temperatures arrive after daybreak Thursday.
Thus while we a showing slightly increased confidence in the freezing
line advancing south to set the scenario for a winter mix Thursday
morning, predominant precipitation types of rain and freezing rain
versus sleet or potentially some light snow at the end of the precip
event hasn`t changed much. Overall amounts of QPF are trending
wetter, but this could also wind up compressing the time window for
rain to change over to a mix before the conveyor belt of moderate to
heavy precip rates pull to the east early Thursday. Thus we`ll
continue to leave our ice accumulation amount forecast minimized
until there becomes a more consistent timing of the change-over.
The 12Z model cycle continues to so sharp drying late Thursday and no
significant trailing dynamics to move over our part of TX for any
potential snowfall of significance. However, some silent 10 percents
are offered in the PoPs to suggest a low potential going into
Thursday night. Friday night continues to be a good bet for a
widespread hard freeze. The Friday high temps are forecast to creep
above Freezing before another hard freeze settles in Friday night. A
weak disturbance in the westerlies could set up a brief wintry mix
opportunity Saturday, but there aren`t enough model groupings to
warrant any mention of weather chances outside of some light rain
showers through Sunday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 52 59 51 70 53 / 50 100 20 0 -
Austin Bergstrom Intl Airport 49 59 50 71 52 / 50 100 30 - 10
New Braunfels Muni Airport 52 62 51 73 52 / 70 90 10 0 10
Burnet Muni Airport 49 57 49 71 50 / 50 90 10 0 0
Del Rio Intl Airport 51 74 47 78 51 / 60 - 0 0 0
Georgetown Muni Airport 49 57 50 69 52 / 40 90 20 0 -
Hondo Muni Airport 54 67 46 76 51 / 80 70 - 0 -
San Marcos Muni Airport 51 60 50 72 51 / 60 100 20 0 10
La Grange - Fayette Regional 54 61 54 71 55 / 30 100 50 10 10
San Antonio Intl Airport 53 63 51 72 53 / 70 90 - 0 -
Stinson Muni Airport 54 65 51 76 55 / 60 90 - 0 10
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...09
Long-Term...17