Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/01/23
Area Forecast Discussion
National Weather Service Corpus Christi TX
559 PM CST Tue Feb 28 2023
...New AVIATION...
.SHORT TERM...
(Tonight through Wednesday night)
Issued at 246 PM CST Tue Feb 28 2023
Not a lot of change in the short term period as we are under the
control of ridging at the moment. A weak shortwave will push
around the north side of the ridge tonight into tomorrow, but
without any deeper moisture to work with, will not expect much
expect some mid level clouds with it. Fog potential tonight is a
bit lower as a moderate LLJ develops, especially over the Coastal
Plains. Think we`ll still see some marine fog developing late
evening into the overnight, but expect vis reductions to be
limited. Even farther inland, surface winds still 8-10kt should
keep dense fog from developing. Low temps tonight will again be in
the mid and upper 60s for most of the area.
Temperatures will continue to inch up with values tomorrow a touch
higher than we are seeing today. Currently have no record in the
forecast, but all 3 climate sites will be within just a few
degrees, so it can`t be ruled out! While probabilities of 90
degrees or better are quite high for the Rio Grande Plains and
Brush country, 100 degree probs are pretty low...generally under
50%. We will expect breezier conditions in the late morning and
early afternoon for the eastern part of the area as the lingering
LLJ mixes down. Gusts over 30 mph will be possible. Wednesday
night looks a lot like tonight with surface winds remaining
elevated to limit fog to mainly coastal areas and low temps in the
upper 60s.
&&
.LONG TERM...
(Thursday through next Monday)
Issued at 246 PM CST Tue Feb 28 2023
Key Messages:
- Hot with near record highs possible Thursday
- Fire Weather Watch in effect from Thursday afternoon through Friday
morning
- Marginal to Slight risk of severe thunderstorms Thursday into
Thursday night
Well above normal with near record breaking temperatures can be
expected across South Texas on Thursday ahead of an approaching
frontal boundary Thursday afternoon/evening. Ensemble members from
both the GFS and ECMWF indicate over 90% probability of temperatures
exceeding 100 degrees over portions of the Rio Grande Plains
Thursday, with near 100% exceedance of 90 degrees temperatures
across the western half of the CWA. Current forecast calls for highs
to range from the mid 80s across the Victoria Crossroads to near 102
degrees over portions of the western Brush Country.
An upper level low over the Desert Southwest early Thursday morning
is progged to transition across the Southern Plains Thursday
afternoon into the evening hours, sending an associated cold front
into the region. Very dry and breezy conditions can be expected
ahead and behind this boundary, leading to Elevated to Critical fire
weather concerns across most of South Texas. A Fire Weather Watch
remains in effect beginning Thursday afternoon and continuing
through Friday morning. Minimum RH values will fall into the teens
out west, with values below 30% along the coast Friday. The front
will also bring a chance for isolated thunderstorms mainly heading
into the evening period Thursday night. SPC is highlighting eastern
portions of the CWA under a Marginal to Slight risk of severe
thunderstorms during this period. However, confidence in occurrence
is not very high at this time, as the window of opportunity is
expected to be short. In general, there will be enough instability
with SBCAPE values above 1000 J/kg, forcing from the boundary, some
energy from the parent upper level system, and potentially enough
moisture. But, models continue to indicate a stout cap in place,
which would hinder development. Portions of Webb and La Salle county
could also briefly experience windy conditions to Advisory levels
Thursday evening.
High pressure is expected to take a hold over the weekend, putting
an end to the rain/storm chances and maintaining dry and benign
weather conditions. Onshore flow is expected to return by Saturday,
with moisture gradually increasing as we head into early next week.
A gradual warming trend will also follow into next week, with highs
bouncing back into the 90s over portions of the Brush Country by
Tuesday.
&&
.AVIATION...
(00Z TAFS)
Issued at 559 PM CST Tue Feb 28 2023
MVFR ceilings will continue to affect the Victoria Crossroads
early this evening while gusty southeast winds linger over the
Coastal Bend. Low level flow will strengthen to 25-35 knots over
the coastal plains this evening. SREF probabilities for IFR ceilings
increase by mid evening over the coastal plains with HRRR model
depicting IFR ceilings moving inland to the eastern Brush Country
by 06Z. With stronger low level flow, fog that develops over the
coastal plains overnight is expected to be MVFR. IFR ceilings
may reach COT/LRD between 11-15Z. Ceilings will lift to MVFR over
the coastal plains by mid morning and VFR by early afternoon.
Southerly winds will become gusty over the coastal plains by 16Z
and continue through Wednesday afternoon.
&&
.MARINE...
Issued at 246 PM CST Tue Feb 28 2023
Moderate southeasterly flow continues tonight and Wednesday with
sea fog once again possible tonight. Patchy sea fog development
is possible again tonight into early Wednesday morning. A strong
cold front will move across the coastal waters Thursday night into
Friday with a strong offshore flow developing in its wake,
leading to Small Craft Advisory conditions. Gusts to near gale
force (34 knots or greater) will be possible over the offshore
waters. Winds will diminish through the afternoon Friday, then
return to onshore Friday night. A generally weak to moderate
onshore flow will then persist through the weekend.
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 69 88 69 90 / 0 0 0 0
Victoria 69 87 69 86 / 0 0 0 20
Laredo 70 96 68 102 / 0 0 0 0
Alice 68 94 68 96 / 0 0 0 0
Rockport 70 84 69 80 / 0 0 0 10
Cotulla 69 96 67 100 / 0 0 10 0
Kingsville 69 93 68 96 / 0 0 0 0
Navy Corpus 68 85 69 83 / 0 0 0 0
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...Fire Weather Watch from Thursday afternoon through Friday
morning for TXZ229>232-239>246-342>346-442-443.
GM...None.
&&
$$
SHORT TERM...PH
LONG TERM....ANM
AVIATION...TMT/89
Area Forecast Discussion
National Weather Service Des Moines IA
602 PM CST Tue Feb 28 2023
...Updated for the 00z Aviation Discussion...
.DISCUSSION.../Tonight through Tuesday/
Issued at 246 PM CST Tue Feb 28 2023
Key Messages:
-- Light precipitation into tonight; mainly northern half of Iowa
-- Areas of fog possible tonight
-- Increasing winds, wintry precipitation spreads into portions of
southern of Iowa later Thursday into Friday
Details: GOES upper level water vapor imagery shows a trough
dropping along the Pacific Northwest coast with west-southwesterly
flow into the central part of the country. Ahead of this trough, a
shortwave trough will eject from the Intermountain West into the
Dakotas tonight while at the same time surface high pressure departs
the state to the east. Surface winds have started to respond with
mainly easterly winds, but winds at 925mb and 850mb have started to
turn to the southeast and will later turn to the south. Warm air
advection has already started ahead of the approaching shortwave,
but the moisture return flow vector and time period before the
system arrives is short such that moisture continues to look quite
marginal. Forecast soundings today compared to yesterday continue to
show the mid-level saturation, which is apparent on visible
satellite, with saturation occurring top down into the low levels.
The period of phased mid and low level saturation is very short
lived and less than yesterday at this time. Already, light showers
with even perhaps a brief bout of sleet via recent mPING from around
Omaha is lifting out of southwest Iowa this afternoon. Thus, a few
to several hour window of light rain or snow at a given location
remains in the forecast over central and later northern Iowa into
this evening. What still remains uncertain is as dry air works into
the mid-levels and ice introduction is lost on the backside of the
main light precipitation shield, how long and how much moisture
remains in the lowest 1km to support any drizzle or freezing
drizzle. While the 12z GFS dries out the column, the morning runs of
the HRRR, RAP, and NAM all show a 3 to 6 hour period of close to 1km
of saturation. More recent runs of the HRRR and RAP continue to show
marginal if not less saturation depth leading to the decision to
forgo any mention outside of here and briefly in the weather story.
Will need to monitor radar and sounding trends into tonight.
While moisture depth may not be as great elsewhere in the forecast
area, the moisture that does remain below a 1km does lend itself to
fog development. Winds are a bit stronger over northern Iowa so at
this point the higher chance of fog will be over southern into
central Iowa.
The trough that is arriving over the Pacific Northwest today will
dig into the southwestern US and eject into the southern Plains
Thursday night. As this trough lifts northeastward through the
Ozarks and towards Michigan on Friday, it will deepen with both the
00z NAEFS and ECMWF ensemble showing this pressure being at the
minimum percentile of the model climatology. With this strong low
pressure passing southeast of Iowa, stronger winds, especially over
the southern half of the state, is fairly certain, though the
magnitude will vary depending on exact track and eventual pressure
gradient field. At this point, forecast continues to teeter on
advisory. As for precipitation and type, this too will depend on the
low track as that will dictate thermal atmospheric profiles and how
far north the moisture gets into Iowa. The latest cluster analysis
shows an increased number of clusters compared to this time
yesterday. However, the clusters with the most QPF (farther north,
stronger with 500mb low) and the cluster with almost no QPF (weaker,
faster with 500mb pattern) are outliers with around a 10%
probability of occurrence each. With the remaining clusters, each
would have QPF into at least our southern forecast area with the
highest amounts into southeastern Iowa. The northern extent will be
controlled not only by low track, but also by high pressure over
southeastern Canada. This high in conjunction with the storm`s low
will feed dry, easterly air into the northern part of the
precipitation shield, which will result in a quick tailing off of
precipitation with northern/northwestward extent. Further, this dry
air feed will likely delay precipitation onset by several hours over
what is currently shown.
After this system departs into the Great Lakes Friday night,
Saturday through the day Sunday will be dry. There is not a strong
push of cold air behind the Friday system such that temperatures
will be similar on Saturday as they were Friday in the 30s and 40s
and more centered in the 40s to perhaps low 50s south on Sunday.
&&
.AVIATION.../For the 00Z TAFS through 00Z Wednesday evening/
Issued at 601 PM CST Tue Feb 28 2023
Main concern will be increasing moisture, fog and lower cigs aft
05-06z. Light precipitation with some uncertainty in coverage,
possible central to north. For now will cover with VCSH. Will
watch for potential FZDZ at MCW, but currently expect precip to
exit prior to temps falling to below 32. Cigs will improve aft
17z. /rev
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Ansorge
AVIATION...REV
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
532 PM CST Tue Feb 28 2023
...New AVIATION...
.SHORT TERM...
(Tonight through Wednesday night)
Issued at 239 PM CST Tue Feb 28 2023
Synopsis/Mesoanalysis: The beginning of the period will be marked by
continued well above normal high temperatures for early March
standards. A loosely-defined dryline will be draped near and just
west of the area, and could possibly mix east into portions of Val
Verde and Edwards County on Wednesday afternoon. A pair of subtle
mid-level impulses -- both unconnected to the primary upper
disturbance arriving later on Thursday -- will pass near or over the
area tonight and tomorrow night, bringing slight chances for showers
and thunderstorms across the southern Edwards Plateau, Hill Country.
While expected to be limited in their coverage, an isolated
strong/severe storm cannot be ruled out as the second impulse
arrives tomorrow night and into Thursday morning.
Tonight: Another round of patchy fog is possible across Hill
Country, the Coastal Plains, and I-35 corridor. Some of this could
become locally dense by early morning. The first of the two impulses
discussed above will track largely to our north through the period,
keeping most shower and storm potential north of our area. Can`t
completely rule out an isolated shower over Burnet, Llano, and
Williamson Counties.
Tomorrow: Well above normal temperatures continue. Should the
dryline mix east into Edwards and Val Verde County, a combination of
dry air and breezy west winds could support isolated near-critical
fire weather conditions.
Predawn Thursday: Discussed in the synopsis, a second perturbation
is forecast to emerge from Mexico and cross northern portions of the
area early Thursday morning. Likely tied to forcing provided by the
feature, a handful of the 12Z HREF members depict the development of
isolated convection across the southern Edwards Plateau shortly
after midnight. These forecasts then show this activity clipping our
Hill Country counties prior to its exit to Central Texas by sunrise
Thursday/the conclusion of the period. Despite the nocturnal
timing/stable surface layer depicted in forecast soundings, steep
mid-level lapse rates would provide between 1000-2000 J/kg of MUCAPE
in this activity. Combined with 60+ knots of effective bulk shear,
this would likely support at least some potential for large hail in
any storms that manage to develop. This is confirmed in 12Z HRRR
Neural Network guidance, which shows an area of 10-15% large hail
probabilities in storms forming during this period. We will continue
to closely monitor trends during this portion of the short term.
&&
.LONG TERM...
(Thursday through Tuesday)
Issued at 239 PM CST Tue Feb 28 2023
A cold front will move through the CWA during the day Thursday. Deep
moisture will be limited to the eastern half of the area and this is
the only part of the CWA with chances for rain. The best timing will
be during the afternoon and evening. Models are showing sufficient
instability and vertical wind shear for storms to be strong to
severe. SPC has our eastern counties in a Slight risk for severe
thunderstorms and a Marginal risk farther west. Behind the front
strong northwesterly winds will bring drier air. Winds will be 20 to
30 mph with gusts up to 60 mph. A Wind Advisory will likely be needed
and a High Wind Warning will be possible over the southern Edwards
Plateau and Rio Grande Plains. The combination of dry air and strong
winds will also make for critical fire weather conditions and we have
a Fire Weather Watch in effect for Thursday afternoon and evening.
Temperatures will be cooler behind the front. Temperatures Friday
will be about 15 degrees cooler than Thursday. Dry weather will
settle in for the rest of the period. A slow warming trend will start
over the weekend and continue through Tuesday.
&&
.AVIATION...
(00Z TAFS)
Issued at 531 PM CST Tue Feb 28 2023
Generally high clouds and winds under 12 knots through around
midnight. Low clouds and areas of fog return tonight, with MVFR/IFR
ceilings, possibly LIFR at times, favored over the I-35 corridor
sites. Dense fog looks most likely over the southern Edwards Plateau
and Hill Country, although it could reach SAT in the early morning
hours. These low clouds look to lift and clear around 17-18Z with
southerly flow under 15 knots expected through the afternoon hours.
VFR conditions are forecast through the period at DRT, with breezy
westerly wind expected in the afternoon hours.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 67 85 67 84 / 10 10 20 40
Austin Bergstrom Intl Airport 66 85 66 86 / 10 10 20 40
New Braunfels Muni Airport 66 87 65 88 / 10 10 20 20
Burnet Muni Airport 64 83 64 83 / 10 20 20 40
Del Rio Intl Airport 65 95 66 92 / 0 0 10 0
Georgetown Muni Airport 66 84 66 84 / 10 20 20 40
Hondo Muni Airport 65 90 64 92 / 0 10 20 10
San Marcos Muni Airport 66 86 65 87 / 10 10 20 30
La Grange - Fayette Regional 68 83 68 82 / 10 10 10 40
San Antonio Intl Airport 67 88 66 89 / 10 10 20 10
Stinson Muni Airport 68 90 67 92 / 10 10 10 10
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
&&
$$
Short-Term...Quigley
Long-Term...05
Aviation...27
Area Forecast Discussion
National Weather Service Grand Forks ND
953 PM CST Tue Feb 28 2023
.UPDATE...
Issued at 953 PM CST Tue Feb 28 2023
No major changes to the forecast as of the mid evening update. A
band of heavier snow currently centered just north of the I-94
corridor correlates well with a region of 700 hPa frontogenesis,
as analyzed by RAP mesoanalysis. This has lead to reductions in
visibility under 1 mile, with brief reports down to 1/4 mile at
times. Generally expecting this area of snowfall to lift east-
northeastward into west central Minnesota over the next few hours
and weaken as it becomes detached from the more favorable forcing.
As the surface low over west central South Dakota continues to
progress eastward, the expectation within latest ensemble guidance
is for the lower level frontogenetical features to introduce the
next band or bands of heavier snowfall to southeastern North
Dakota. Prolonged periods of 1" per hour rates are anticipated
underneath these heavier bands, that will result in accumulating
heavy snow in some areas. Will continue to monitor the progression
and evolution of this surface low and its attendant forcing
features through the overnight hours.
UPDATE Issued at 729 PM CST Tue Feb 28 2023
As of early this evening, made some minor adjustments to the
forecast. Latest RAP mesoanalysis indicates an area of 700 hPa
frontogenesis over east central North Dakota leading to some
enhanced snowfall rates over Griggs and Steele counties. Further
southward near the border of the Dakotas, a few regions of 850
hPa frontogenesis were analyzed, coinciding with a lifting band of
enhanced snowfall rates over southeastern North Dakota. Within
these bands, there have been reports of visibility dropping as low
as 1/4 mile at times, despite winds in the 10-15 kt range. Did
adjust PoPs and QPF slightly northward to account for the area of
700 hPa frontogenesis. Otherwise, the winter storm generally
remains on track at this time, but will continue to monitor short
term trends as the system evolves.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 301 PM CST Tue Feb 28 2023
Key Messages
- The Winter Storm event is still pretty much on track, the only
change on this shift was to add Mahnomen/South Clearwater into
the advisory
- Banded snow events bring sharp gradients across individual
counties, but not all areas will get the higher end snow
amounts
- Where the snow bands occur may not be known until they set up,
so further refinements are still possible
Starting off with the late afternoon into tonight period, cloud
cover continues to expand across the area. The surface low is now
in western South Dakota. Although the regional radar shows echoes
along the Interstate 94 corridor already, this is just mid level
virga, as no stations are reporting anything at the surface. So
the onset of light snow may not arrive until early evening. The
time period with the heaviest snow rates (1 inch or more per hour)
will likely be tonight, with the rates slowly tapering off from
west to east on Wednesday.
The Interstate 94 corridor southward toward the North and South
Dakota border still looks to be the favored area for the most
snow. Models continue to show weak CAPE and a potential prolonged
period of frontogenetical forcing there. There could still be a
slight north or southward shift to this area. And not all areas
within the warning will see the higher end amounts. There will
likely be large gradients across individual counties. As mentioned
above, where these heavier snow bands set up may not be evident
until late, so further refinements to these headlines are
possible.
Another uncertainty is how fast the heavier snow rates end, and
the gustier northeast winds kick in. Visibilities in blowing snow
are always the worst when there is falling snow. If the snow tails
off sooner on Wednesday, the increasing winds may not result in
continued low visibilities. Overall, the winds do not look to be
that strong. If they are stronger than anticipated, that would
also play into conditions being worse for longer on Wednesday.
For now, think that there will be some blowing and drifting, but
not as bad as some events. So stay tuned for further updates.
.LONG TERM...(Thursday through Tuesday)
Issued at 301 PM CST Tue Feb 28 2023
Key Message:
There is around a 20% chance of at least advisory-type impacts from
accumulating snow and wintry mix starting Sunday, lasting through at
least Thursday.
Discussion:
Going through this weekend, the upper pattern shifts from zonal flow
aloft behind a compact upper low moving through Upper Midwest (all
outcomes suggest a track well west of our area), with weak troughing
at the surface moving through the region Friday. This weak troughing
may bring some light snow, although no impacts are expected from
this at this time. Ahead of this surface trough, winds become breezy
out of the southwest as the pressure gradient strengthens some,
bringing the potential for some patchy blowing and drifting snow.
Getting into next week, the synoptic pattern starts to become more
conducive for increased precipitation chances. Aloft, ridging builds
over the Northern Plains downstream of a stout upper trough digging
into the PacNW. Waves of energy and moisture ejecting out of this
trough is expected to traverse the Rockies into the Northern Plains,
eventually through our area as early as Sunday. Ensemble guidance
starts to deviate on the number and magnitude of these waves,
although most depict this scenario with generally increased precip
chances. Differences in how strong and orientation/placement of the
downstream upper ridge will influence how the deep the PacNW upper
trough digs, directly influencing the ejected waves and moisture.
Ultimately, starting Sunday there are multiple chances next week for
several periods of snow and wintry mix, and thus impacts as well.
With the potential for multiple waves to bring accumulating snow and
wintry mix, there is around a 20% chance for one or more periods of
advisory-type impacts between Sunday and next Thursday.
Current ensemble guidance suggests any one wave will not be robust
enough to favor warning-type impacts, although cannot be ruled out
as a potential outcome at this time. This is especially true if the
upper trough in the West finally breaks eastward into the Plains. A
cluster of ensemble members signal this break as early as next Thu-
Sat timeframe. Ultimately, chance for warning-type impacts through
next Thursday is currently less than 10%, although will be something
to watch given the potential for the upper trough to break eastward,
especially getting toward late next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 556 PM CST Tue Feb 28 2023
This evening, conditions will continue to deteriorate, especially
at FAR, as a system lifts northward out of South Dakota. Moderate
to heavy snowfall rates will lead to visibility reductions across
southeastern North Dakota through the overnight hours into
Wednesday morning. Increasing winds by Wednesday morning will also
lead to potential aviation impacts from BLSN as well. Further
northward, impacts are expected to be lesser, with only light snow
anticipated, although any accumulating snow with increasing winds
may result in BLSN impacts. Otherwise, an improvement in overall
conditions is expected by Wednesday afternoon as snowfall chances
and gusty winds begin to subside.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Winter Weather Advisory until 3 PM CST Wednesday for NDZ024-
028>030.
Winter Storm Warning until 3 PM CST Wednesday for NDZ038-039-049-
052-053.
MN...Winter Weather Advisory until 3 PM CST Wednesday for MNZ002-
022>024-027-028-030>032-040.
Winter Storm Warning until 3 PM CST Wednesday for MNZ003-029.
&&
$$
UPDATE...Rick
SHORT TERM...Godon
LONG TERM...CJ
AVIATION...Rick
Area Forecast Discussion
National Weather Service Morristown TN
1103 PM EST Tue Feb 28 2023
...New UPDATE...
.UPDATE...
Issued at 1055 PM EST Tue Feb 28 2023
Forecast remains on pretty good track this evening. Blended in
NBM10th to the dewpoints as they were running a tad high,
otherwise, everything else was left unchanged aside from
interpolating most recent observations. Light winds and relatively
lower moisture in the air will result in favorable cooling
conditions. That will be somewhat balanced with high clouds
advecting in overnight. Overall, lows will still be above normal.
&&
.SHORT TERM...
(This evening through Wednesday)
Issued at 312 PM EST Tue Feb 28 2023
Key Messages:
1. Dry conditions will continue through most of Wednesday with
rain chances in southern areas by the evening.
2. Unseasonably mild temperatures will continue.
This Evening/Tonight
Currently this afternoon, a fairly benign pattern is in place
with zonal flow aloft and high pressure near the Great Lakes
region. A frontal boundary is well to our south near the Gulf
where much of the moisture is also in place to its south.
Overnight, high pressure will shift eastward with some height
rises and strengthening of the upper jet to our north, where
another low will move into the Northern Plains. This will
gradually increase southerly flow towards morning with
unseasonably mild temperatures continuing.
Wednesday
Increasing southerly flow will continue during the day on
Wednesday, pulling the aforementioned frontal boundary and Gulf
moisture to the north. It is also during this time that another
upper jet streak will extend out of the Deep South, leading to
increasing upper divergence as the left-exit region moves
overhead. For the near-term period, the main result will be an
increase in low-end rain chances by the early evening, mainly in
southern portions of the area. With some instability in place, a
few thunderstorms are possible as well. However, the notably
active weather is expected to be after the near-term period.
&&
.LONG TERM...
(Wednesday night through next Tuesday)
Issued at 312 PM EST Tue Feb 28 2023
Key Messages:
1. Moderate to heavy Rain is expected late Wednesday night through
Thursday morning with the potential for localize flash flooding.
Main area of concern is across the Plateau and central and southern
sections of the Tennessee valley.
2. Strong to severe storms are possible across southeast Tennessee
and southern Plateau late Wednesday night and early Thursday
morning. Main concern is damaging winds and potential of isolated
tornadoes.
3. A stronger system will impact the area on Friday with strong
winds likely area-wide, especially across the Mountains and
Foothills.
4. A line of showers and thunderstorms will move across the area
Friday, mainly in the morning. Some of these storms could be severe
with damaging straight line winds and isolated tornado possible.
Discussion:
For Wednesday night, a jet streak will move across the lower Ohio
and Tennessee valley strengthening the fronto-genetic forcing along
a west-east frontal boundary over Tennessee. Very strong fronto-
genetic forcing evident over the area which will produce widespread
showers and storms. NAEFS shows high anomaly of PW and 850mb
transport winds along with good warm rain process. Any training of
storms along this boundary may produce flash flooding.
Another concern is the potential of severe storms late Wednesday
night and early Thursday morning. Model soundings are showing 0-1km
shear of 40kts, effective shear of 50-55kts, 0-3km CAPE of 100-150
and low LCL heights. Latest HRRR and HREF show potential of 2-5km
updraft helicity tracks into the southern Plateau, southeast
Tennessee and Cherokee and Clay counties of North Carolina.
Will be monitoring the potential of tornadoes across these area
during the next 24 hours.
For later Thursday, frontal boundary becomes quasi-stationary just
south of the area. A very strong upper level system lifts northeast
from the southern Plains toward the Ohio and Tennessee valley
Thursday through Friday. Strengthening upper level jet increasing to
155 kts will move across Tennessee into the central Appalachians.
Interesting that a distinct tropopause intrusion is noted across the
Tennessee valley strengthening the overall wind field. NAEFS
shows anomaly strong 700-850mb jet over the region for late
Thursday night and Friday.
This strong jet energy and large scale ascent will produce a line of
showers and thunderstorms that will move across the region Friday.
Another potential of damaging straight line winds and isolated
tornadoes will be a concern.
The strong wind field and associated tight pressure gradient will
produce strong winds ahead and behind this line of storms friday.
Wind advisories valley to high wind warnings mountains and foothills
are expected.
For Friday night, this system lifts away from the area with return
of more tranquil conditions through early next week.
&&
.AVIATION...
(00Z TAFS)
Issued at 631 PM EST Tue Feb 28 2023
VFR conditions and light winds 10kts or less for the 00Z TAF
cycle. Clouds will increase throughout the day Wednesday, with low
SCT/BKN VFR cigs possible at CHA/TYS late Wednesday afternoon into
the evening. Perhaps a shower or storm near CHA before 00Z but not
enough confidence to include in TAFs at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 51 76 61 71 / 0 30 100 80
Knoxville McGhee Tyson Airport, TN 48 76 58 69 / 0 10 100 70
Oak Ridge, TN 46 74 57 69 / 0 10 100 70
Tri Cities Airport, TN 43 74 55 67 / 0 10 100 60
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...BW
LONG TERM....DH
AVIATION...KRS
Area Forecast Discussion
National Weather Service Pittsburgh PA
834 PM EST Tue Feb 28 2023
.SYNOPSIS...
Dry, warm weather will return tomorrow as a ridge builds across
the Ohio River Valley. Shower activity returns along a warm
front early Thursday morning. A strong low pressure system will
bring widespread rainfall and wintry mix near I-80 on Friday,
headlines may need to be issued.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Only change to the overnight period was to tweak low
temperatures down a degree or two in some spots, given the
relatively dry and calm air mass with crossing high pressure.
Still, temperatures may steady out towards dawn as the high
moves east, allowing warm advection to commence ahead of a
Middle Ohio Valley warm front.
The remaining low clouds will continue to erode across areas
north and east of Pittsburgh, but will be replaced by mid clouds
over the same region, streaming from Michigan. Surface wind will
settle on an easterly direction by sunrise.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
The first day of meteorological spring is certainly going to feel
like spring (meteorological spring begins Mar. 1 while astronomical
spring starts on the equinox). During the morning on Wednesday, a
shortwave trough embedded within an elongated ridge will pass
through the region. Precip chances will be lacking with increase
subsidence. However, wind gusts will increase throughout the
day with stronger vertical wind shear from the southwest. Hi-
Res models suggest winds just above the surface ranging between
25-30kts. Gusts will likely be stronger during peak heating.
Combined with the warmer air, temps are expected to rise into the
60s for most of the forecast area, with some places up north of I-80
potentially remaining below 60 and some locales south of I-70
possibly reaching 70 degrees! See the climate section below
regarding the potential for record highs.
For Wednesday night into Thursday morning, convection should
return to portions of the region, mostly south of Pittsburgh,
warm front advances into the region over southern Ohio. The NAM
is considerable aggressive with moisture and a few model
soundings suggest the potential of strong thunderstorms give the
low-level wind shear profile. However, the HRRR and RAP analysis
are suggesting the mixing of dry air due to elevated subsidence
and snuff out instability chances. Given the range of
possibility, kept a slight chance of thunder for areas I-70. The
passage of a cold front from the Northeast will likely clear out
precip chances. Temperatures will still remain above average
through Thursday with some potential clearing and weak cold
advection.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Long term models continue to eject a strong upper-level low out
the West Coast and mid-week and enter the Ohio River Valley by
early Friday morning. However, ensemble models have certainly
backed off the the potential for widespread snow and wintry mix
given a dominate ridge along the East Coast. With a mostly
westerly track of the center of the low, warm advection will
likely overspread the eastern Ohio/western PA/and northern West
Virginia. Isolated areas, near I-80, could see the potential
for light ice accumulation given a strong surface high north of
NY instilling dry, cool conditions at the surface. Also, with
the noted dry air, wet bulbing could drastically change the
temperature profile and even sleet and wet snow could briefly be
observed. Updated the Hazardous Weather Outlook (HWO) for the
threat for mixed precipitation for a few counties to our north,
a Winter Weather Advisory may need to be issued in the future if
confidence increases.
Elsewhere, heavy rainfall may create a rapid rise along our
small creeks and streams. The 50% percentile of the NBM is over
an inch of QPF for a majority of the region (with higher amounts
over eastern OH), however short range models have been accounted
for during this time period. Model soundings at the moment have
aggressive Precipitable Water values (above 1.0 for numerous
hours), however with rapid intensification of the this system, a
dry slot may setup earlier than expected and wain precip
amounts. A Marginal risk is noted for Excessive Rainfall on the
Weather Prediction Center site. However, there still remains a
large amount of uncertainty areas exceeding flash flood
guidance.
The backside of the low pressure system will likely to be
experienced until Saturday due the system being rather large in
scale. There is a chance that precip will change from rain to
snow with northwest flow and lake enhancement. However, strong
fetch across Lake Erie at the moment looks unimpressive at only
20-25kts.
High pressure will likely build across the region Sunday into
Monday and warm dry weather will return.
GFS ensemble models are foreseeing the return of a ridge axis
midweek. However, the center of the axis may be positioned
further west than the current one we are under. If that outcome
develops, we could be seeing cooler than average temperatures
for mid-March.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
MVFR stratocu should continue to erode this evening as high
pressure builds across the region. Clearing is expected at PIT
by 03Z, though FKL and DUJ will likely see stratocu cigs until
after 06Z. Wind will veer to the east toward morning ahead of an
approaching warm front. A low level jet across Ohio will also
result in a potential for LLWS at ZZV.
Southerly surface wind gusts from 20-25kt are expected by mid
to late morning after the passage of the warm front. Mid level
cigs are expected, and FKL and DUJ could also see a shower with
FROPA where slightly more favorable moisture and ascent is
progged.
.OUTLOOK...
Restrictions in showers are possible Wednesday night and early
Thursday with a crossing cold front. Widespread restrictions and
rain are expected late Thursday night through Friday night with
low pressure, though FKL and DUJ could see a wintry mix at
precip onset. Gusty wind and a period of LLWS is also expected.
Restrictions are then expected to continue through Sunday in
cold W-NW flow and upper troughing.
&&
.CLIMATE...
Record of near record high temperature is expected Wednesday.
Below is the current record in jeopardy for March 1st, and the
forecast high.
Station...Record/Year...Forecast High
HLG 65/2016 66
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Hefferan
NEAR TERM...CL
SHORT TERM...Hefferan
LONG TERM...Hefferan
AVIATION...WM
CLIMATE...50
Area Forecast Discussion
National Weather Service Raleigh NC
1035 PM EST Tue Feb 28 2023
.SYNOPSIS...
Weak high pressure building into the area from the north will push a
dry, secondary cold front into the area this evening. This front
will lift north as a warm front Wednesday. A deepening low pressure
system crossing the Ohio Valley and Great Lakes regions will drag
a cold front through the area late Friday.
&&
.NEAR TERM /TONIGHT/...
As of 1035 PM Tuesday...
Still anticipate fairly quiet weather for the rest of tonight, but
the possibility exists for an hour or two of gustiness overnight.
The latest surface analysis shows last night`s frontal system well
to our E and NE, with a surface high centered over NY/PA drifting
eastward, its cooler and denser air poised to build down into NC via
a backdoor front noted over E VA and extreme NE NC. Area 00z
soundings including at GSO remain dry, and dry air is noted upstream
(to our NW and W) from 925 mb on up, although near-surface RH is
higher esp over E VA/NE NC near and NE of the backdoor front. This
front will continue pushing to the SW overnight, and numerous high-
res models depict a brief surge of higher sustained winds and gusts
from the NE as the denser air arrives. As such, have included this
short uptick in winds overnight spreading NE to SW, but have trimmed
back speeds a bit from what high-res guidance was showing, given
that these predicted stronger gusts have yet to be realized over SE
VA. Otherwise, expect mostly clear skies giving way to high clouds
in our SW sections associated with the next frontal system now over
the S Plains. Made minor adjustments to temps/dewpoints the rest of
tonight, but overall still expect lows in the 40s except around 50
in the far S. -GIH/AA
Earlier discussion from 242 PM: A weak and transitory surface high
building south into the NE and mid-Atlantic States will will push a
dry, secondary cold front into the area this evening, before
stalling along the SC-NC state line.
Gusty westerly winds of of 17 to 22 mph will gradually diminish
through the remainder of the afternoon with winds becoming light
this evening and tonight as the surface ridge briefly shifts south
over the area. Skies across the forecast area will remain mostly
clear overnight. The exception could be across the far southern
zones, where some stratus could develop INVOF the stalling front.
&&
.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
As of 235 PM Tuesday...
The surface front stalled along the SC-NC state line will lift back
north as a warm front on Wednesday. The RAP and GFS show a rather
extensive stratus/stratocu deck within the initial surge of strong
low-level warm moist air advection. Cannot rule out a stray shower
or sprinkle, but it should remain mostly dry through the afternoon.
Highs will be comparable to today, perhaps a few degrees cooler,
ranging from lower 70s north to upper 70s/near 80.
A lead upper disturbance and zone of strong WAA embedded within a 35-
40kt SWLY LLJ will result in widespread showers overspreading the
area during the late evening and overnight hours, with latest timing
showing a very wet morning rush hour commute for most of central NC.
Lows in the mid/upper 50s north to lower 60s elsewhere.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
As of 350 PM Tuesday...
Showers and isolated storms Thursday morning will start the morning
wet as a disturbance moves across the area. By the afternoon on
Thursday this disturbance will move out of the region and Central NC
is expected to have a lull from wet weather for the afternoon. As
the next low pressure system moves across the Mississippi Valley
precip chances will return late Thursday night/ early Friday morning
as warm front will move across the region from southwest to
northeast late Thursday night. This will generally affect the more
of the western and northern portions of the FA, but all areas have
some precip through the day. After the warm front lifts across the
region, the surface low with an extending cold front into the Gulf
Coast will moves across the TN and OH valley and into the region by
Friday afternoon and evening. While shear vales continue to show
strong values in the upper 30s to low 40kts, CAPE vales remain under
500 J/kg. This does not rule out however the chance of thunderstorms
with a few of these thunderstorms becoming severe. The time frame
expected for the thunderstorms will be afternoon Friday and
diminishing by late Friday night. One thing to note is that as the
front approaches the region Friday expect wind gusts to pick up in
the morning to be around 20kts and by the afternoon around 30 to
35kts. Winds will be expected to decrease by Saturday morning as the
actual front moves across the region.
Temperatures Thursday will be low 70s in the north to low 80s in the
south. As the frontal boundaries move through the area Friday
temperatures will be a tad tricky as timing will be everything, for
now high temps will be in the low/mid 70s north to upper 70s and low
80s south.
By Saturday the surface and upper level forcing will be displaced
well north of the area. The surface cold front will take its time
moving through NC, ultimately not making it all the way through and
off the coast until Saturday night. Thus, temps will remain above
normal with highs in the upper 60s. Weak ridging aloft will build
across the area Sunday into next week, with cooler and drier air
settling in place. Highs will generally reach the low to mid 60s,
with overnight lows ranging from the upper 30s to the mid 40s. Dry
weather through the period.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 657 PM Tuesday...
There is high confidence in mostly VFR conditions at all terminals
through the 24 hr TAF period. A weak cold front is expected to push
through the area tonight, maintaining mostly clear skies with light
enely turning sfc winds. A warm front will then move north Wednesday
spreading low-level moisture across our area. Associated periods of
MVFR ceilings will be possible at KFAY/KGSO/KINT/KRDU mid Wednesday
morning through early afternoon before scattering back to VFR by
early evening. Confidence in how thick these low-level clouds will
be is a little low at this point, but think these terminals have the
best chance for MVFR ceilings to form in that time span. Otherwise,
sfc flow should remain light and turn more swly Wednesday afternoon.
Outlook: A lead upper disturbance and zone of strong WAA embedded
within a 35-40kt SWLY LLJ will result in widespread showers and
associated sub-VFR restrictions overspreading the area Wednesday
night and into the day on Thursday. The LLJ will likely bring a
threat of LLWS Wednesday night as well. A significantly stronger
storm system and attendant cold front will impact the area on
Friday, bringing another round of showers and possibly storms, with
associated sub-VFR conditions to central NC Thursday night and
Friday. Strong SWLY winds with frequent gusts of 30 to 40 kts is
also expected Friday ahead of the cold front.
VFR conditions will return Friday night and should remain
predominately VFR through the weekend.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...CBL/Badgett
NEAR TERM...Hartield/AA/CBL
SHORT TERM...CBL
LONG TERM...CA/Leins
AVIATION...Luchetti/CBL
Area Forecast Discussion
National Weather Service Blacksburg VA
723 PM EST Tue Feb 28 2023
.SYNOPSIS...
High pressure builds in briefly through Wednesday before
another system drifts into the region Thursday, bringing showers
and possibly storms. Another wave of low pressure develops
Thursday night into Friday, keeping rain chances in the
forecast. Temperatures remain above normal.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 710 PM EST Tuesday...
Clouds develop late tonight...
Wind speeds have diminished and the combination of light wind
and clear sky will result in good cooling conditions this
evening. Early Wednesday morning as low level winds turn to the
east and southeast, low clouds will develop along and east of
the Blue Ridge. High clouds also fill from the west so the
temperature toward sunrise will be small. Added the late night
cloud cover in and made minor adjustments to low temperatures,
otherwise no changes for the forecast tonight.
As of 1240 PM EST Tuesday...
Sunny skies prevail across the entire area, and winds, while
still gusty in spots, are trending lower in speed. This trend
should continue through the afternoon, and become even more
noticable after sunset.
Temperatures also continue to climb faster than the pace of the
ongoing forecast. Have adjusted the hourly forecast trends
accordingly and increased the high temperature forecast by a
category at most location. Have also trended a little lower on
dew point trends through the afternoon. Both trends have yielded
lower expected minimum relative humidities, especially in the
eastern sections.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 200 PM EST Tuesday...
A few rounds of rain for the second half of the week...
A warm front passes over the forecast area starting late
Wednesday. Despite being fairly detached from the central low in
the Western Great Lakes, high shear, modest instability and
PWATs in excess of 1 inch will assist in rain processes
overnight Wednesday into Thursday morning.
There`s little break between this system and an approaching
better formed system tracking out of the southern plains. The
attendant warm front will cause the formation of showers
Thursday afternoon, and as the low moves into the OH valley into
Friday morning, the cold front will pass over the area Friday
afternoon and evening. Instability will be minimal, but given
stronger dynamics than the previous warm fronts, and a strong
shear profile, have included a slight chance of thunder for most
of the CWA on Friday with the cold frontal passage. For all of
Wednesday, Thursday and Friday`s fronts and rain, total rainfall
amounts look to range from 1-1.5" inches, with some localized
amounts up to 2". This is not raising any strong concerns for
flooding threats given it will fall over a 60 hour period, but
rain rates will be given strong consideration in the forecast
over the coming days.
A warm air mass behind Wednesday`s front will reintroduce the
above normal temperatures that have been customary of late.
Highs in the 60s and 70s on Thursday will only be tempered by
showers and a cold front a little on Thursday, dropping
temperatures to the upper 50s and 60s. The moist environment and
clouds will hold temperatures from falling much below 50 in the
overnight periods.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 230 PM EST Tuesday...
Dry weekend ahead...
Behind Friday`s cold front, strong pressure rises will lead to
strong winds Saturday as a broad surface high establishes its
presence over the Mid-Atlantic. This is the most exciting
weather all weekend, the high pressure suppresses any precip
chances. The next opportunity for precipitation will be a Rocky
low expected to spin through the plains on Monday, and reach our
area by Monday night or Tuesday. The drier conditions over the
weeknight will be a change of pace from the wet week we have
had, but temperatures will remain above normal in the extended
portion of the forecast.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 1230 PM EST Tuesday...
Wind speeds have diminished to less than 10 knots. Early
Wednesday morning as low level winds turn to the east and
southeast, MVFR clouds will develop along and east of the Blue
Ridge. This is supported by GLAMP, HRRR and 3KM NAM guidance. High
clouds also fill from the west.
Once mixing begins Wednesday morning, winds become southwest and
some gusts of 15 to 20 kts are likely in the mountains. Any
rainfall associated with the approaching will not arrive until
after the 00Z end of the TAF forecast period.
Average confidence for ceiling, visibility, and wind.
Extended Aviation Outlook...
Wednesday night through Friday night will be a very active
period with multiple rounds of showers, and perhaps some daytime
thunderstorms on Friday. There will be of periods for sub-VFR
conditions, especially Wednesday night and Thursday, and again
Friday and Friday night.
Gusty conditions are expected before and after the cold frontal
passage Friday afternoon through early Saturday.
Saturday into Sunday a return to mainly VFR conditions are
expected with dry high pressure.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...DS/SH
NEAR TERM...AMS/DS
SHORT TERM...VFJ
LONG TERM...VFJ
AVIATION...AMS/DS
...Update to aviation forecast discussion...
.DISCUSSION...
Issued at 235 PM CST Tue Feb 28 2023
Main focus of the forecast is on the storms system expected
Thursday and Friday morning. It looks like the forecast is going
to come down to the track of the system, which models continue to
show variation in. So confidence in the forecast is marginal. In
general the system initially looks warm for rain across a good
chunk of the area with some snow on the tail end that could amount
to an inch or two.
20Z water vapor imagery shows a broad upper trough over the
northwestern half of the CONUS. A jet streak was noted on the
western side of the upper trough just off the west coast. Another
shortwave was lifting through the northern plains. At the surface, a
weak trough of low pressure bisected the forecast area with
southerly winds to the south and a more easterly wind north of the
boundary. A surface low was noted over the northern high plains.
Models continue to show a closed upper low lifting across the
southern and central plains Thursday night. Good synoptic forcing
for vertical motion is expected to lead to some light precip
developing on Thursday. Though the better dynamics could impact
the forecast area mainly during the overnight hours Thursday and
into Friday morning. 00/06Z guidance showed the NAM to be an
outlier with the track of the closed upper low shifted northwest
of the other solutions. But the 12Z ECMWF has trended slightly
towards a solution similar to the NAM while the GFS and Canadian
continue to show a track mainly south and east keeping the heavier
QPF axis to the southeast of the forecast area. So there remains
a fair amount of uncertainty in the track of the storm system. To
complicate the forecast, models don`t have a whole lot of cold air
in place until the upper low begins to lift north. So precip
could be liquid for a majority of the forecast area into Thursday
evening. Have continued with the national blend with only minor
changes for the forecast. This brings generally light
precipitation into the area during the day Thursday with a gradual
change to a wintery mix through the night. Models show a narrow
corridor where a warm nose over falling temps could produce a
brief period of freezing rain. This looks to be short lived and
any ice accumulations should be minor. As for snow, I have
questions with the NAM`s solutions which shows the potential for a
lot of snow. 15Z SREF ensemble plumes at MHK have outcomes
ranging from nothing to over 15 inches. The NAM is the deepest
with the low pressure system and wraps up more cold air into the
back side. Looking at the NBM, the probability for 4 or more
inches of snow around 10 to 20 percent. Again think the track of
the system, whether it is south or a little further to the
northwest, will be the deciding factor in snow amounts and don`t
have a great deal of confidence in those values just yet.
For tonight through Wednesday, dry weather is expected to persist
with limited moisture and forcing anticipated. The main change to
the forecast was to include some patchy fog and low stratus across
northeast KS late tonight and through mid morning Wednesday. The
last several runs of the RAP have shown some consistency with a
saturated boundary layer developing behind a weak frontal
passage. With clear skies and light winds ahead of the boundary,
there could be some radiational fog develop around midnight.
Better mixing behind the front is expected to favor more stratus
than fog towards sunrise. The clouds should mix out by noon
leaving good insolation. This however looks to be offset by some
weak low level cold air advection. So highs Wednesday should be a
little cooler with readings in the middle and upper 50s. Lows
tonight are forecast to drop back into the 30s.
For the weekend and into next week, A shortwave is progged to pass
over the central plains Saturday morning. Moisture looks to be
limited with this wave so POPs are only around 10 percent. Then
models develop a nearly zonal pattern that slowly becomes more
southwesterly into next week. This should help temps moderate and
think highs could be around 60 or a little warmer by Sunday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 521 PM CST Tue Feb 28 2023
Main concern for this forecast will be the potential for ifr/lifr
vsbys and cigs at TOP and FOE as forecast soundings show the
potential for fog development along with low stratus from 09Z-14Z.
Forecast soundings for MHK show less mist potential, so mainly
have mvfr vsbys after 09Z. Winds becoming light and variable then
become northwest generally 10kts or less after 10Z. Outside of any
fog development vfr conditions are expected.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Wolters
AVIATION...53