Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/03/23
Area Forecast Discussion
National Weather Service Columbia SC
722 PM EST Thu Mar 2 2023
.SYNOPSIS...
Isolated to scattered showers are possible through tonight as a
frontal boundary lifts north of the forecast area. A cold front
will move through the Carolinas Friday evening with showers and
thunderstorms possible along with strong and gusty winds. The
front will slowly move off the coast Friday night with high
pressure and dry air over the region for Saturday through
Monday. Another front and increased moisture will move into the
region Tuesday and Wednesday.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Skies remain mostly cloudy across the region this evening.
Isolated to scattered showers continue moving through the
forecast area, favoring northern and western counties which are
closer to a stationary front over North Carolina. Isentropic
lift is expected to increase as a weak front boundary passes
through the CWA. This boundary and lift combined with ample
moisture is enough to warrant chance PoPs gradually decreasing
from south to north through the overnight hours. Clouds and
rain keep temperatures from falling much meaning another warm
night is in store with lows mostly in the lower 60s.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
Friday and Friday Night: A strong and deepening surface low
will move northeastward from the mid MS Valley into the Ohio
Valley on Friday then shift to the New England coast Friday
night. The stalled boundary over the forecast area will shift
northward through the day as strong southwesterly flow develops
and overspreads the region as the pressure gradient tightens in
response to the deep low to our west. Some light showers will be
possible in the morning hours mainly north of the I-26 corridor
and over the western Midlands with pops decreasing into early
afternoon as isentropic lift shifts northward. Pops then
increase again late afternoon and evening as the front moves
into the region.
The threat of severe weather continues for our area late Friday
afternoon and evening, although the timing of arrival continues
to look closer to the evening for our area and confidence is
limited in overall impact. While forecast soundings and HREF
guidance showing limited but sufficient instability (SBCAPE
500-700 J/kg) combining with extremely strong shear with 0-6km
values around 70-75 knots the most significant upper forcing
will remain to our northwest. Another limiting factor is a mid
level capping inversion due to warm 700mb temps. The frontal
boundary by 00z Saturday is forecast to be just entering the
Upstate and then pushing through the forecast area Friday
evening. Any isolated storms that develop ahead of the front
look to be limited by the capping inversion and Hi-res guidance
suggests a line of convection along the front but weakening as
it pushes through the area. The greatest severe threat appears
to be west of the I-20 corridor and during the 5pm-11pm time
frame. Damaging wind gusts will be the primary through but an
isolated tornado cannot be ruled out. SPC has updated their day
2 outlook and shifted the slight risk further west with only our
western Midlands and upper CSRA counties in the slight risk,
with the remainder of the forecast area in a marginal risk.
Aside from the severe weather threat, winds are expected to be
breezy Friday and Friday evening due to the strong pressure
gradient with southerly winds increasing by late morning and
becoming gusty with max wind gusts still expected in the 35 to
40 mph range but remaining below our wind advisory criteria.
After collaboration with CHS we will be issuing a Lake Wind
Advisory from noon Friday through 7am Saturday. Temperatures
will be a little tricky depending on cloud cover and how
fast/slow the warm front develops and shifts northward.
Saturday and Saturday night: Cooler, dry high pressure will
build into the forecast area on Saturday with PWATs less than
0.5 inches and no rain chances. Skies should be mostly clear
with plenty of sunshine and some weak downsloping low level flow
offsetting the weak cold advection. Temperatures are expected
to be a bit cooler with highs ranging from around 70 northwest
Midlands to mid 70s eastern Midlands. Strong radiational cooling
is expected Saturday night as the surface high settles over the
central Appalachians with a clear and dry air mass in place.
Overnight lows should fall into the 40s.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
The extended forecast will feature generally benign weather
with ensemble mean 500mb flow fairly zonal throughout the entire
period.
Surface high pressure will be over the forecast area on Sunday
with a dry air mass in place with PWATs less than 0.5 inches.
However, high pressure will shift offshore on Monday allowing a
more southerly flow to develop. This will enable some warm and
moist advection back into the region (PWATs back to 150-200% of
normal) ahead of the next frontal boundary which is expected to
move into the area midweek as shortwave energy moves across the
Great Lakes into New England over the top of a broad upper
ridge. Increased chances of rain are expected midweek but there
is uncertainty regarding the specific details and will lean
toward the NBM for pops. Temperatures will remain above normal
through the period with Sunday being the coolest day of the
forecast then a gradual warming trend early next week.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Mainly VFR this evening then then deteriorating to MVFR toward
morning.
Pressure ridge centered south of the area with High low-level
moisture across the region. Weak front or trough to the north
of the terminals. The boundary may be near the CAE/CUB terminals
around 12z then lift north. Radar indicating showers mainly
focused near the trough. Ceilings VFR at the moment with
widespread strato- cumulus and some higher clouds. HRRR and
other guidance indicating clouds will lower to MVFR toward 12z
Friday and continuing through late morning. Can`t rule out some
IFR stratus. As strong mixing develops by afternoon in response
to a deepening low pressure system moving northeast out of the
Plains, expect ceilings to rise to VFR. Light and variable
winds overnight then becoming south to southwest 15 to 25 knots
with higher gusts in the afternoon. Can`t rule out some light
showers overnight but impacts to terminals should be minimal.
Some showers possible in the morning. During the afternoon,
convection will be approaching from the west but not expected to
impact terminals until closer to 00z Saturday.
EXTENDED AVIATION OUTLOOK...A strong cold front will cross the
region Friday night with restrictions near frontal passage
associated with potential strong thunderstorms. Strong west
winds behind the front diminishing Saturday morning.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...Lake Wind Advisory from noon Friday to 7 AM EST Saturday for
GAZ040-063>065-077.
SC...Lake Wind Advisory from noon Friday to 7 AM EST Saturday for
SCZ016-018-020>022-025>031-035-037-038-041-115-116-
135>137.
&&
$$
Area Forecast Discussion
National Weather Service Des Moines IA
554 PM CST Thu Mar 2 2023
...Updated for the 00z Aviation Discussion...
.DISCUSSION.../Tonight through Thursday/
Issued at 303 PM CST Thu Mar 2 2023
Key Messages:
-- Trend southeastward continues with a glancing shot of wintry
precipitation Friday morning
-- Monitoring fog potential tonight northern and central Iowa
-- Another wintry precipitation round Sunday into Monday morning
Details: Low clouds over the state this morning are now relegated to
northern Iowa with mid and high level clouds moving into southern
Iowa. These latter clouds are streaming well ahead of a positively
tilted shortwave trough that is departing the Desert Southwest as a
150knot, 250mb jet streak has moved across the central part of the
country. Comparing 12z observations to 12z initialized model
guidance, the strength of the 500mb low is within a mb or two and
location is similar as well. Overall, overnight model runs and this
morning`s runs today have continued to increase confidence that a
more southerly track will occur, which will give more of a glancing
shot of wintry precipitation to areas well south and east of Des
Moines with the highest impacts over southeastern Iowa. The trough
over the southwest will move eastward today, sparking an expected
high end severe weather event over the Arklatex region. As this
trough lifts northeastward tonight, a negative tilt and deepening of
the 500mb low and surface low are still on track. The 12z and 18z
NAM remains on the northern side of the envelope of surface low
pressure tracks, but it is now passing near or just south of St.
Louis versus north of St. Louis as in previous days. Rest of 12z
deterministic models are south of St. Louis and as far south to near
the Kentucky border.
Well to the northeast of the surface low will be the surface high
pressure, which will play a critical role in delivering dry air on
winds from the east. Currently, this high is centered over the
southeastern Ontario province with an extension down toward Lake
Superior. As the high pushes east into southern Quebec and the low
lifts into the middle Mississippi Valley, will see that dry air
funneled into the 900 to 750mb layer per forecast soundings. The 9z
RAP/12z HRRR only have shallow saturation indicating just clouds
with their south tracks. The 12z/18z NAM at Centerville and Ottumwa
both show the effects of the mid-level dry air delaying deep
saturation and precipitation onset while the 6z/12z GFS struggles to
deeply saturate at all. As mentioned above with the southerly track
and this dry air, forecast focuses PoPs and QPF over our far south
central into southeastern counties with snow amounts under an inches.
While the NAM remains an outlier with its track, if it were to
verify soundings and cross sections show a short period of moderate
omega with an isothermal profile just below 0C in the lesser known
dendritic growth zone. This would yield a fairly wet, sticky snow
with rates that could approach an inch per hour. However, our
current forecast is not the NAM at this time and the precipitation
that does fall will exit the area by early Friday afternoon. While
our winds will become gusty as a strong pressure rise/fall couplet
follows the path of the low, confidence is that the strongest winds
will be south of the state and below advisory level in our forecast
area.
The other thing to monitor tonight will be the fog potential over
central into northern Iowa. The HRRR and the 12z HREF both show the
potential for lowered visibility toward Friday morning. However,
soundings are split on whether this will end up being a low stratus
deck or fog. Winds look to become more favorable toward and after
3am and have added a little patchy fog in a few places, but will be
something for the evening and overnight shifts to update.
Not far behind as Friday`s low tracks away from the area will be a
shortwave trough passing through the northern Plains into the Great
Lakes on Saturday. Forecast soundings show limited and short-lived
saturation such that have kept the forecast dry outside of a mention
of sprinkles and flurries over northern Iowa. Another sheared out
shortwave moves toward Iowa by late Sunday into Monday with a
baroclinic zone setting up south of the state. Stronger QG
convergence and warm air advection will help to saturate the column,
though ice introduction may not last long before it is lost. Also
seen in forecast soundings is a warm, above 0C layer centered around
850mb over northern Iowa. So, as hydrometeors fall, they will melt
in this layer. At this time, surface temperatures will largely be
above 32 degrees to keep the precipitation either rain or snow. This
precipitation will exit the state during the day Monday. Beyond
Monday, the upper level pattern diverges amongst the deterministic
models with more zonal flow in the GFS/CMC and a longwave trough
in the ECMWF by Wednesday. At this point, it does look like
another window of precipitation will be possible toward midweek,
but confidence is low in the details.
&&
.AVIATION.../For the 00Z TAFS through 00Z Friday evening/
Issued at 544 PM CST Thu Mar 2 2023
Continue to see some MVFR stratus residing over northern Iowa with
areas near to just north of the IA/MN border seeing some ceilings
drop into IFR with these lingering clouds. Have continued with the
lower clouds over at least KMCW for the next few hours, but the
clouds may not fully move out before additional clouds increase
again tonight into the overnight hours. Continuing to monitor
trends for the development of fog and/or low stratus, mainly
between 09-15Z Friday, with HREF probabilities suggesting a
moderate (40-60%) chance for the development of low visibilities
or ceilings over parts of central into northern Iowa. Confidence
in exact impacts remains on the lower side so updates are likely
in future issuances. Additionally, some light precipitation may
reach towards the vicinity of KOTM Friday morning with increasing
winds due to a system passing south of the state.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Ansorge
AVIATION...KCM
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
548 PM CST Thu Mar 2 2023
.Discussion...
Issued at 312 PM CST THU MAR 2 2023
Overview:
Rain and a rain snow mix will be possible overnight. Minimal
accumulations are expected, but slushy conditions may be possible
in a few locations Friday morning. Dry weather with above normal
temperatures return over the weekend.
Thursday night and Friday:
Model agreement has certainly improved
as we head into the Thursday night into Friday system. Confidence
still remain quite low though due to a handful of determinist and
ensemble outliers and borderline temperatures.
Thankfully more models are now in agreement of the slight east
shift of the track of the low which will bring the deformation
zone to north and eastern parts of the area. As far as
temperatures go, NAM continues to be a bit of an outlier, bringing
in much cooler temperatures faster allowing for a transition to
snow by Friday morning. If this scenario pans out, there is
potential for seeing multiple inches of snow across central and
northern parts of the area. Other deterministic models continue to
lack and cold air, and delay cold air advection until after the
passage of precipitation. In these scenarios, most would remain
primarily rain with only a little potential for a rain snow mix
Friday morning. This would bring snow accumulations to less than
an inch and mainly in eastern and northern parts of the area.
Looking at some of the shorter range models, most remain on the
warmer side, limiting snowfall accumulations to under 1 inch. A
few models, such as the 12z HRRR keep our precipitation all rain
and any snowfall accumulation will remain well east of our
forecast area.
Now for a look at some of the ensembles, a similar picture is
painted. Looking the the euro ensembles, a vast majority of
members limit much snowfall with limited cold air. On the other
hand, there are some that do bring snowfall up to about 5 inches
in far eastern parts of the area near Kirksville. The ensemble
mean however, is just for trace amounts of snow. The GFS
ensembles keep precipitation all rain for the most part, though a
few members hint at potential for a change to snow for a few
hours.
With all this information, confidence is highest in remaining
primarily rain or a rain snow mix with minimal accumulation. But
due to persistent model spread a scenario is certainly not out of
the question that a narrow band of heavy wet snow develops across
northern Missouri. With a narrowing of forecast spread, have
decreased snow totals a bit in this forecast, due to increasing
confidence in a primarily rain scenario. But keeping in mind that
a snowfall event is certainly not out of the question, and the
spacial gradient for highest amounts will be fairly tight.
Snowfall and precipitation potential is expected to end quickly
for west to east on Friday morning. Surface temperatures will
also quickly warm to well above freezing across the area.
Therefore any locations that do see snow may be dealing with a
slushy mess on roadways early Friday morning.
Besides precipitation, winds will also be a factor. A strong
pressure gradient can be expected on the back side of this
anomalous low pressure. Sustained winds out of the north of 25 to
25 mph can be expected Friday morning. With the slight eastward
shift in models, the strongest wind gusts will remain east of our
area, however gusts up to about 40 mph will still be a
possibility.
Rest of the forecast:
After this system comes to an end Friday afternoon, quiet weather
will return for the remainder of the forecast. Near zonal upper flow
will persist over the weekend. On Saturday sunshine will return with
highs already back to above normal, and in the 50s across the
area. Sunday will be a pleasant day as well with most in the 60s
and a few locations reaching near 70. Fairly quiet conditions
continue as we head into the work week, but a few shortwaves to
the north may bring several low end chances to see precipitation
again.
&&
.Aviation...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 543 PM CST THU MAR 2 2023
VFR conditions ahead of incoming rain later tonight. A few showers
have tried to work their way south this afternoon, however the
bulk of showers should start arriving at our terminal airspace
closer to the midnight hours. Rain is anticipated to transition to
a sloppy rain/snow mix close to sunrise, with minimal if any
accumulation is expected. Conditions will drop to MVFR overnight,
and possibly to IFR Friday morning. CAMs have weather drying up by
late Friday morning, with breezy winds upwards of 15-20 knots.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...HB
Aviation...Klaus
Area Forecast Discussion
National Weather Service Goodland KS
840 PM MST Thu Mar 2 2023
.SHORT TERM...(This afternoon through Friday night)
Issued at 1245 PM MST Thu Mar 2 2023
Overview: Height rises /shortwave ridging/ aloft will prevail
over the region tonight into Friday -- as a robust upper low
progresses ENE from the Southern Plains to the Central MS River
Valley. Broad cyclonic flow aloft will prevail over the region
thereafter. A small amplitude wave -- presently situated ~500 mi
west of Vancouver Island, B.C. -- will move ashore the PAC NW
tonight -- progress southeastward into the central Rockies (Fri
evening) then eastward across the Central Plains (Fri night).
Through Tonight: With the upper low (and strongest upper forcing)
progressing eastward across TX/OK this aft/eve -- well south of
the Tri-State area -- forcing will be relegated to the passage of
a SW-NE oriented shear-axis. Current and recent runs of the HRRR,
RAP, and NAM NEST indicate little -- if any -- measurable
precipitation in association with this feature. With mostly clear
skies, light/variable winds, and a relatively moist airmass
(characterized by dewpoint depressions ~15F this afternoon) over
the region.. patchy fog cannot be ruled out AOA sunrise Friday
morning (mainly in the 09-14Z time frame).
Fri-Fri night: With height rises /shortwave ridging aloft/ --
expect mostly clear skies and a warming trend. Mid-upper level
cloud cover will increase from the west Fri evening.. as the
aforementioned small amplitude wave approaches from the WNW. Light
precipitation /snow/ may accompany this feature as it progresses
eastward across the Tri-State area Friday night. The progressive
nature of the upper wave -- i.e. relatively short `window of
opportunity` and small amplitude suggest that significant/
impactful precipitation is unlikely. Simulated reflectivity and
precipitation forecasts via the latest runs of the HRRR and NAM
NEST presently indicate liquid equivalent precipitation on the
order of a few hundredths of an inch (a dusting to ~0.5" snow
accum) -- mainly during the late evening and overnight hours
(03-12Z Sat).
.LONG TERM...(Saturday through Thursday)
Issued at 123 PM MST Thu Mar 2 2023
A rather unsettled pattern looks to setup across the plains for the
extended period with a prolonged period of well below normal
temperatures. Synoptically, a long wave trough originating from
the NW will slowly work its way towards the plains with weak waves
of energy emanating from it for the weekend and into the early
part of the week.
Saturday, will be cooler in wake of some rain/snow chances the night
before. Cloud cover will linger for the majority of the day allowing
temperatures to remain cooler in the upper 30s to low 50s. Focus
then turns to Sunday as warm front moves north across the area as
winds becoming more SSW throughout the day. High temperatures for
the day are forecast in the mid 50s to upper 60s across the entire
area. The warm temperatures and SW wind will lead to a drier
airmass moving into the area which will lead to near critical to
perhaps a few hours of critical fire conditions for locations
south of Interstate 70 where RH values are forecast to be in the
mid teens. Forecast soundings show breezy winds around 15-20 mph
with gusts of 25-30 mph possible if mixing can be fully realized.
A cold front will then move into the area Sunday evening/night
(uncertainty with timing exists) allowing for a wind shift to the
NW.I`m not seeing any stronger winds with the frontal passage
currently despite decent pressure rises, winds aloft are actually
weaker than near the surface. With the dry conditions in place and
an anticipated wind shift first responders will want to continue
to keep up to date with the current forecast especially if a fire
were to ignite.
Monday through the remainder of the forecast period will see below
to well below normal temperatures. The above mentioned long wave
trough approaches the area as it does so colder air will advect into
the plains as the trough blocks warmer air from returning northward.
A Sudden Stratospheric Warming Event has happened recently across
the Arctic. When this occurs it leads to a displacement of the polar
vortex which allows the cold air from the Arctic to move southward
into the mid latitudes. This events lead to the potential for cold
air outbreaks, past Sudden Stratospheric Warming Events occurred
in January of 2019 and January of 2021. Guidance so far does keep
the coldest of the air over the upper Midwest for this period.
Confidence is high in the below normal temperatures occurring for
this period, after collaboration with surrounding offices trended
the forecast to the 25th percentile NBM for temperatures. Those
with farming/agricultural interests will want to keep up with the
most up to date temperatures forecast.
Periods of snow also do appear possible throughout the week with
light accumulations currently appearing possible. It is
interesting to note that the GFS forecast soundings do indicate
some SB CAPE present which would lead to the perhaps some quick
hitting bursts of snowfall. Uncertainty is high regarding the
exact location and timing to currently nail down exact locations
of snow fall.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 840 PM MST Thu Mar 2 2023
KGLD...VFR conditions are expected through the period. A west wind
around 6kts at taf issuance will increase slightly Friday morning
before veering to the northwest at 12-14kts with gusts around
20kts from 17z-21z. After 22z, winds veer to the north at speeds
up to 10kts. Some light snow is forecast to move through the area
and could impact the terminal around/shortly after 05z.
KMCK...VFR conditions are expected through the period. A west wind
around 6kts at taf issuance will continue through Friday morning
before veering to the northwest at speeds of 11-12kts from
17z-22z. After 23z, north winds up to 10kts quickly become light
and variable. Its possible for some light snow to be near/at the
terminal after 05z. For now, just have a mention in the vicinity.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...Vincent
LONG TERM...Trigg
AVIATION...99
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
949 PM EST Thu Mar 2 2023
.SYNOPSIS...
An active cold front approaches the area from the west Friday
morning. There is a potential for severe thunderstorms ahead of this
front, after which dry high pressure will arrive over the weekend
and linger into the first part of next week.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 945 PM Thursday: Scattered to numerous showers continue to
stream eastward across the area this evening. Coverage will increase
overnight to occasional showers as the boundary moving south across
the area now moves back northward as a warm front. Temps have slowly
cooled this evening, with overnight temperatures to remain nearly
steady or warm slightly. No storms are expected tonight with precip
generally light. Lows will be nearly 20 degrees above normal, close
to the normal highs for this time of year.
The bigger story for the area is expected to happen tomorrow as a
deepening upper low and negatively tilted trough ejects across the
TN and Ohio Valley. The low and associated strong cold front are
anticipated to cross the CWA Friday afternoon into the evening.
Ahead of the front, a warm front should slowly lift to the north and
settle near or about the I-40 corridor. Southerly surface flow
should allow for a moist boundary layer. Guidance suggests surface
based instability ahead of the front around 500-1000 j/kg, which is
expected to contribute to strong and possibly severe thunderstorms.
Currently, CAMs have 0-1km SRH hovering around 300-500 m2/s2,
however the possibly limiting factor to severe weather is the warm
layer at the mid-levels. This could inhibit some of the severe
potential with dry air entrainment reducing the potential for
stronger updrafts. With this said, latest CAM guidance from the HRRR
does has high STP values across the CWA, especially along the I-85
corridor, which does raise concerns and confidence at the potential
for a semi-discrete mode. Wind will be the primary threat for this
system, but given the environment these storms will have to work
with, we cannot rule out the possibility for tornadoes east of the
Carolina foothills. For the winds associated with the cold front a
Wind Advisory will be in effect from 1pm Friday through 7am Saturday
for the Carolina mountains. Showers and storms should linger through
this forecast period and taper off overnight from west to east.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
As of 1250 PM EST Thursday...A strong sfc cyclone continues to track
northeast of the area early Fri night as an attendant frontal zone
likely produces showers and thunderstorms across the FA. This
activity will be short-lived, possibly exiting east by midnight with
lowering chances of severe activity. Soundings across the ern zones
show limited to no potential of sfc-based instability aft 00z Fri,
yet stg deep-layered shear could help generate a few cells capable
of producing strong outflows. A southern stream area of high
pressure builds in from the west with little llvl CAA, however,
mixed winds remain quite strong and a tightening p/grad will keep
winds elevated with advisory level gusts possibly reached/maintained
across the higher NC mtn elevations thru mid-morning Sat. Deeply dry
air builds thru the day Sat and persists into Sun with a developing
broad ulvl ridge axis approaching thru the period. Good subs will be
had and LCLs remain quite dry, while any sigfnt Ci is relegated
north. Thus, expect very good early March insol which will allow
temps to remain abt 8-10 degrees abv normal each day. Winds will
also weaken during this time with no new products anticipated. The
flow on the front side of the high will advect in lowering sfc tds
mainly across the NC/SC Piedmont Sun and RH values will probably
drop into the 25-30 percent range, yet winds will be a limiting
factor for much of a notable fire-wx concern.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 1245 PM Thursday...No major changes were made to the ext range
fcst. The guidance continues to show a stg ulvl ridge dominating the
pattern Mon with a deeply dry airmass maintained over the SE region.
A better chance of fair-wx Cu developing during the afternoon Mon
with Ci crossing the ridge, however, max temps shud have no problem
reaching a few cats abv normal in an unchanged airmass. The upper
pattern becomes more zonal Tue into Wed while an upper s/w supports
a sfc cyclone pushing into the Glakes area. Upper forcing remains
quite weak over the srn states and instability will be low-end ahead
of an approaching weak frontal zone Tue. For now, have kept thunder
mention nil as upper-level cloud cover increases thru the day and
parcel ascent is shunted underneath an h75 inversion. Still expect
rain showers with the front, mainly across the NC mtns and NE GA,
with an unsettled and moist airmass persisting into Wed possibly
instigating more widespread shower activity. Max temps will remain
quite warm Tue with highs in the u70s possible east of the mtns and
arnd 70 F in the mtn valleys. On Wed, expect a cool down behind the
front, yet max temps shud still reach abv normal levels by a few
degrees.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: VFR expected into the evening with periods of
light showers moving across the area. A boundary dropping south
across the area has turned winds to the NW. Winds will remain
generally light but may return to the SW through the early overnight.
The boundary returns north toward daybreak with winds turning NE to
SE. MVFR cigs develop at this time with more widespread showers then
Winds turn S to SW and gusty by afternoon as a cold front approaches
from the west. Vsby becomes VFR but cigs remain IFR to low MVFR.
Have a PROB30 for TSRA during the afternoon as storms move in ahead
of the cold front.
Outlook: Skies clear and precip ends Friday evening as the cold
front moves east of the area. Gusty NW winds are expected. Dry and
somewhat cooler high pressure with diminishing winds returns for the
weekend with VFR conditions prevailing through Monday. A frontal
system may bring precip and restrictions on Tuesday.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...Wind Advisory from 1 PM Friday to 7 AM EST Saturday for NCZ033-
048>053-058-059-062>065-501-503-505.
SC...None.
&&
$$
SYNOPSIS...SBK
NEAR TERM...CP/RWH
SHORT TERM...SBK
LONG TERM...SBK
AVIATION...RWH
Area Forecast Discussion
National Weather Service Lincoln IL
844 PM CST Thu Mar 2 2023
.SYNOPSIS...
Issued at 210 PM CST Thu Mar 2 2023
A storm system will bring heavy rain to much of central Illinois
starting around or after midnight tonight and continuing into
Friday afternoon. Rain will transition over to snow for portions
of the region, especially along and north of I-74 Friday afternoon
where some accumulations are expected. Strong northeast winds
will gust 40 to 50 mph much of the day Friday. Dry weather returns
to the forecast this weekend along with mild temps in the 40s and
50s.
&&
.UPDATE...
Issued at 844 PM CST Thu Mar 2 2023
After an early look at the 00z models and coordinating with
surrounding offices, issued a Winter Weather Advisory for McLean,
DeWitt, Piatt, Champaign, and Vermilion counties. This is where we
currently have higher confidence that a mesoscale band of wet,
f-gen driven snow will develop Friday afternoon. 1-2" snowfall
rates are being shown by some of the high-res solutions, which
combined with northeast to north winds gusting near 45 mph would
cause very low visibility. Snowfall amounts are still in question
with the complicating factors of warm/wet ground and afternoon
snowfall during higher March sun angle, all of which could drive
SLRs down to 5 or 6:1. We will continue to assess the suite of
guidance overnight with tweaks to snowfall amounts/locations and
possible headline changes on the 3 AM forecast package.
UPDATE Issued at 744 PM CST Thu Mar 2 2023
Early evening water vapor imagery indicated a deep closed mid-
level low spinning over western TX. In the difluent flow ahead of
this feature, low pressure was developing over southern TX, and is
forecast to race northeast into southern IL by 18z Friday.
Scattered showers were already moving into southern/southwest IL
this evening in response to strong warm advection aloft. This will
slowly advance north overnight, fighting a very dry layer below
700 mb noted on forecast soundings and the 00z ILX sounding. By
midnight we expect good coverage of showers south of I-70, with
this area expanding north of the I-72 corridor by daybreak.
Heaviest QPF overnight is focused south of I-70, with totals
around 0.75-1.00" by 12z. Northeast winds will gradually
strengthen as the MSLP gradient tightens between surface ridging
north of the Great Lakes, and low pressure deepening to sub-990 mb
in central Arkansas by 12z. 25-35 mph gusts will be common late
tonight. With thickening cloud cover and a well mixed boundary
layer lows should only drop about 5 degrees from current readings,
reaching the mid 30s to lower 40s for most of the CWA.
&&
.SHORT TERM...(This evening through Friday)
ISSUED AT 210 PM CST Thu Mar 2 2023
A deep, closed H5 low is spinning over southern New Mexico this
afternoon and is progged to reach ArkLaTex region by late tonight.
Strong surface cyclogenesis will occur in response to this wave as
the surface low lifts across Arkansas overnight to near the
bootheel of Missouri midday Friday. Strong warm air advection will
begin to overspread central Illinois overnight and continue into
Friday morning resulting in widespread rain across the region. As
the surface low passes into Indiana Friday afternoon, strong
frontogenetical forcing will result in dynamic cooling of the
column that will cause rain to change over to snow for portions of
the forecast area, mainly near/north of the I-74 corridor.
* Heavy Rain: There continues to be a strong signal for heavy rain
across portions of central and southeast Illinois. Precip
amounts of 1 to 2 inches are favored southeast of I-55 and there
could be some localized amounts in excess of 3 inches south of
I-70. HREF LPMM indicates a narrow swath of 3-5 inches may fall
across portions of southern Illinois including our far
southeastern counties where some instability is present
supporting a thunderstorm threat. See the hydro section below
for information on area rivers.
* Severe Weather: A severe threat will be present near and south
of the low track which may clip our far southeastern forecast
area (south of I-70). RAP indicates that dew points pooling in
the upper 50s and lower 60s will be present immediately ahead of
the low which will contribute to MLCAPE values of 500-700 J/kg
within a strongly sheared environment. Strong 0-3km shear
vectors oriented perpendicular to an expected line/broken line
of storms in the warm sector may contribute to a threat for
mesovorticies with an attendant wind and tornado threat. While
the severe weather threat is more favored to our south, we will
have to closely monitor the low track and see if we get a
glancing blow in our far southeast counties.
* Winter Weather: Forecast changes giving you whip lash? You`re
not alone. Initial northward (more rain) trends in guidance have
since reversed bringing heavy snow potential back into portions
of central Illinois. That said, there still remains uncertainty
with placement of the heaviest snow fall and snow amounts due
to temps near the freezing mark and lingering uncertainty in
where the strongest mesoscale forcing from frontogenesis sets
up. A band of strong frontogenesis is still in play Friday
afternoon with the latest RAP suggesting a band will set up in
the vicinity of the I-57 corridor and slowly translate northeast
through the afternoon. Steep lapse rates atop this strong
forcing should allow a deep vertical response and set the stage
for dynamic cooling that will allow precip to transition over to
snow with heavy snow rates in excess of 1 inch per hour
possible at times. This window for heavy snow does appear to be
fairly short lived across central Illinois which will limit
accumulations. In terms of snow efficiency, there remain a
number of concerns or limiting factors. The dendritic snow
growth zone remains relatively shallow with steeper lapse rates
cutting through this zone. Strong low level winds and shear will
also act to fracture ice crystals further lowering snow-to-
liquid ratios. Surface temperatures may remain at or above the
freezing mark, and pavement temperatures may also stay on the
warmer side given the recent mild/warm spell over the region.
Probabilistic guidance continues to paint a picture of
significant uncertainty. Mean snow accumulations from the HREF
are several inches higher than the 50th percentile, likely due
to a few heftier snow totals skewing the mean, in part due to
unrealistically high snow ratios. At the peak, anticipate SLR
ratios as high as 8 or 9 to 1. While cannot completely rule out
some of the beefier snow totals advertised by some models, have
adjusted the snow amounts down slightly given the aforementioned
concerns and shifted the axis of heaviest snow slightly further
east where there is better model agreement. No headlines
currently planned, but an advisory may be needed at some point
if trends hold.
* Strong synoptic winds: Northeast winds will strengthen
overnight into Friday as the surface low tracks just south of
the I-70 corridor. Wind gusts will peak in the 40 to 50 mph
range Friday afternoon. Will expand the existing Wind Advisory
another tier of counties northward. Winds should very gradually
ease as they back to the northwest behind the departing low
Friday evening and overnight.
.LONG TERM...(Friday night through Thursday)
ISSUED AT 210 PM CST Thu Mar 2 2023
Mercifully, the remainder of the forecast is not anywhere near as
challenging as the first 24 hours. The main upper flow through the
weekend continues to be of Pacific origin, so no particular cold
snap will follow the exiting storm system. Main challenge would be
with temperatures in areas that managed to get any decent snow
cover tomorrow, but even then, the snow should melt quickly and
highs in the 50s will otherwise prevail this weekend. Monday looks
to be the warmest day of the upcoming period, mostly in the 60s.
Main forecast concern for next week will be with a pair of storm
systems Monday and midweek. Initially, the models are showing
decent agreement with keeping the bulk of the Monday impacts to
our north, with mainly some scattered showers southward to about
I-72/Danville. Getting into midweek though, the European model
continues to advertise a broad trough over the western CONUS,
gradually digging into the 4-corners region late in the week. This
solution would have more of a precipitation threat here, but also
fed by a stiff northeast flow which would stunt some of the
moisture spread into Illinois until Wednesday night. The GFS and
Canadian models, meanwhile, keep more of a zonal flow going and
any precipitation largely limited to the Gulf Coast region. The
lack of a moisture flow would favor the drier solutions,
especially at this distance in the forecast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 526 PM CST Thu Mar 2 2023
A strong low pressure system will track into southern IL around
18z/Friday. This will cause increasing northeast winds overnight,
with gusts as high as 40 kt after 15z, veering north during the
afternoon with similar high gusts. Rain and MVFR ceilings will
spread north across the terminals around 11-12z, with ceilings
lowering to IFR a couple hours later. Periods of heavy rain will
mix with or change to snow at KPIA/KBMI/KCMI, with ceilings and
visibilities possibly dropping to LIFR (currently most favored at
KBMI). Conditions will begin to improve toward 00z as precipitation
becomes lighter.
&&
.HYDROLOGY...
Issued at 210 PM CST Thu Mar 2 2023
Still some significant concerns with rivers given the amount of
rain projected from this system. Southeast half of the forecast
area would be most impacted, with the Little Wabash and Embarras
Rivers likely to see very sharp rises on Friday and flooding
develop by late Friday or early Saturday. Steady rises expected on
the mainstem Wabash into the middle of next week.
On the Illinois River, impacts from the heavier rain over the last
week in northern Illinois are working their way down, and there is
a good chance of at least minor flooding from Peoria upstream
early next week. Downstream, more of the impacts from the upcoming
system come into play, and moderate flooding is expected to
develop at Havana and Beardstown toward Monday or Tuesday.
Renewed rises are also expected on the Sangamon River, though
probabilities of minor flooding developing this weekend are highest
on the west and east ends of the river.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from noon to 9 PM CST Friday for ILZ038-
043>046.
Wind Advisory from noon to 9 PM CST Friday for ILZ042>057-
061>063-066>068-071>073.
Flood Watch from midnight tonight to 6 AM CST Friday for ILZ057-
063-067-068-071>073.
Flood Watch from Friday afternoon through Friday evening for
ILZ057-063-067-068-071>073.
&&
$$
UPDATE...25
SYNOPSIS...Deubelbeiss
SHORT TERM...Deubelbeiss
LONG TERM...Geelhart
AVIATION...25
HYDROLOGY...Geelhart
Area Forecast Discussion
National Weather Service North Platte NE
515 PM CST Thu Mar 2 2023
.SYNOPSIS...
Issued at 243 PM CST Thu Mar 2 2023
- A period of light snow is expected Friday night with 1 to 3
inches of accumulation possible across the northwest Sandhills.
- A more active weather pattern arrives next week with
snow chances and temperatures trending to well below normal.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 243 PM CST Thu Mar 2 2023
An upper trough will cross the Pacific Northwest and reach western
MT, ID and nern NV by 12Z Friday. This will bring an increase in
mid and high cloudiness overnight. A pre-frontal surface trough
will turn winds to light westerly overnight. Lows will range in
the lower 20s.
On Friday, a weak cold front will progress through the area. Highs
from 40-45 across nctrl NE, to 45-50 across the south. with the
approach of the upper trough, there will be a chance for rain or
snow across the far northwest Sandhills.
Friday night, the northern stream trough will pass through the
area. The 12Z GFS and 18Z HRRR area in good agreement focusing
light snow accumulations across north central Nebraska. Expanded
NBM POPs eastward to include eastern portions of the north
central Nebraska. HAve likely POPs across the Pine Ridge, and 30
to 50 POPs across the remainder of Cherry and Sheridan County with
snowfall amounts from 1 to 3 inches. This is an increased trend
from the previous forecast. Some low POPS also exist further
south across the southeast pnhdl and southwest Nebraska overnight.
.LONG TERM...(Saturday through Thursday)
Issued at 243 PM CST Thu Mar 2 2023
A chance for light snow is possible Saturday morning across the
northeast as the upper trough exists the area. Slightly cooler
with weak mixing expected.
An upper trough will persist across the northwestern U.S through
Monday of next week, as medium range models diverge on the
synoptic scale pattern through Thursday of next week. Ensemble
guidance supports a progressive quasi-zonal flow pattern through
Thursday of next week. Amplification in deterministic models
exists. Much cooler temperatures are likely as the main cold
front gets pushed south into the Gulf of Mexico by Thursday of
next week. This cooler air will likely get dammed up against the
Front Range with highs only in the upper 20s to lower 30s by next
Wednesday and Thursday.
Regarding snow chances, POPs increase to at least 30 to 40
percent Tuesday night through Thursday. While some of next week
may remain dry, model differences in timing are pronounced.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 514 PM CST Thu Mar 2 2023
Some scattered high cloudiness will move into the area later
tonight. Ceilings will be generally in the 20000 to 25000 FT AGL
range. Toward the end of the forecast period, ceilings will lower
to around 5000 FT AGL at the KVTN terminal late Friday afternoon.
Winds will shift around to the west, then northwest overnight.
Wind speeds will be in the 10 to 15 KT range at both terminals.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Roberg
SHORT TERM...Roberg
LONG TERM...Roberg
AVIATION...Buttler
Area Forecast Discussion
National Weather Service Morristown TN
1008 PM EST Thu Mar 2 2023
...New UPDATE...
.UPDATE...
Issued at 958 PM EST Thu Mar 2 2023
The main change with this evening update was a downward trend in
temperatures as most sites have dropped lower than what the
previous forecast values were. Low temperatures were lowered
slightly with PoPs updated to reflect the slow northward
progression of showers. The main focus continues to be on the high
winds and possible strong/severe storms tomorrow. The latest
high-res model guidance continues to illustrate the extreme nature
of gradient winds expected area-wide with indications for gusts
above 60 mph in lower elevation areas. There has also been a
decent consensus on a more robust broken line of convection to
move through the area during the afternoon. The amount of
available instability continues to be in question, along with the
extreme amount of shear that could almost be too much for storms
get organized. Overall, the message remains the same this evening.
&&
.SHORT TERM...
(This evening through Friday)
Issued at 303 PM EST Thu Mar 2 2023
1. Widespread high winds to impact the area on Friday. Southwest
winds gusts of 50 to 60 mph are expected across the valley
locations, and gusts of 70 to 80 mph across our higher elevations
of the east TN mountains and foothills. Due to the saturated
ground, conditions are more susceptible to down trees and power
lines which will likely cause power outages.
2. A broken line of showers and thunderstorms will move across
the area Friday afternoon. Some of these storms could be strong to
severe with damaging straight line winds the main threat, and an
isolated tornado possible. The greatest potential of tornadoes
will be across the northern Plateau.
Discussion:
For Tonight, a strong upper trough will lift northeast toward the
Ohio and Tennessee valleys. The strong jet structure will allow
the strong cyclogenesis to lift northeast pulling a frontal
boundary north across the region. Isentropic lift will produce
scattered showers over the area. The pressure falls will begin to
tighten the pressure gradients across the Tennessee valley toward
day break with the boundary layer jet strengthening.
Strong mountain wave high winds will initially develop across the
far east Tennessee mountains and foothills before 12Z.
For Friday, the upper level system and associated strong
cyclogenesis will lift northeast toward the Ohio valley.
Impressive 850-700mb jet with NAEFS showing anomaly high wind
field over the Tennessee valley. The 850mb jet of 75kts+ will move
across the region with strong momentum transfer of the low-level
jet to the surface. Even though the wind gusts of 50-60 mph in the
valley may be below warning criteria, saturated ground will make
conditions more susceptible to down trees and power lines. Power
outages Friday are likely.
Beside the gradient induced high winds, a severe threat also
exists. Damaging straight line will be the main concern. Isolated
tornadoes are also possible as 0-1km and effective shear are off
the charts. Limiting factors are the low-CAPE and possible high
LCL heights. Also, the strongest of the synoptic forcing lift
north of the area.
Will need to monitor the potential of tornadoes closely. Latest
HRRR model does show an increasing potential but HREF CAMS showed
the best 2-5km updraft helicity tracks over Kentucky.
For Friday night, southwest winds will slowly diminish with
rainfall ending in the evening.
&&
.LONG TERM...
(Friday night through next Thursday)
Issued at 303 PM EST Thu Mar 2 2023
Key Messages:
1. Not as active during the longterm but still a few chances for
rain, mainly Monday night/Tuesday then again Wednesday/Thursday.
Rainfall amounts will be very light, generally less than a few
tenths of an inch.
2. Temperatures will range from near normal to above normal through
the period.
Quiet weather expected over the weekend and into Monday behind
Friday`s frontal passage. Temperatures near seasonal normals
Saturday as we are under zonal flow, warming back to well above
normal by Monday as ridging builds back in from the south.
Monday night into Tuesday, an upper low will move across the Great
Lakes, with a trailing cold front that will move through our area
from north to south on Tuesday. Precip chances back in place Monday
night through Tuesday due to the frontal passage. Colder
temperatures, back down to normal, on Wednesday. A deep longwave
trough moves into the Rockies/Great Planes Wednesday/Thursday which
causes the previous cold front to lift back north into the area.
Precip chances in place during this time to account for the warm
front in the vicinity.
&&
.AVIATION...
(00Z TAFS)
Issued at 629 PM EST Thu Mar 2 2023
For tonight, the main concern will be periods of lower ceilings
due to periods of light showers, especially at CHA. Reductions to
MVFR or even briefly IFR are possible, in addition to brief
visibility reductions. The main concern with aviation will be
related to winds as an extremely robust system tracks to our
northwest. LLWS is certainly possible for a brief period in the
morning hours but was not included in the TAFs as it will likely
be isolated. Throughout the day, southerly winds will increase to
above 25 kts sustained ahead of showers and storms with
impressively strong widespread gusts to 50+ kts expected by the
afternoon hours. Within any stronger storms, even more intense
winds are possible. These winds will likely continue into the
evening.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 57 74 43 63 / 70 80 10 0
Knoxville McGhee Tyson Airport, TN 56 75 42 59 / 90 70 20 0
Oak Ridge, TN 55 73 41 61 / 90 60 10 0
Tri Cities Airport, TN 52 71 41 56 / 60 80 60 0
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...Wind Advisory from 10 AM Friday to 1 AM EST Saturday for
Cherokee-Clay.
TN...Wind Advisory from 10 AM Friday to 1 AM EST Saturday for East
Polk.
High Wind Warning from 10 AM Friday to 1 AM EST Saturday for
Anderson-Campbell-Claiborne-Grainger-Hamblen-Jefferson-Knox-
Loudon-Morgan-North Sevier-Northwest Blount-Northwest Cocke-
Roane-Scott TN-Union.
High Wind Warning from 10 AM Friday to 4 AM EST Saturday for
Hancock-Hawkins-Johnson-Northwest Carter-Northwest Greene-
Southeast Carter-Southeast Greene-Sullivan-Unicoi-
Washington TN.
High Wind Warning from 4 AM Friday to 1 AM EST Saturday for
Blount Smoky Mountains-Cocke Smoky Mountains-Sevier Smoky
Mountains-Southeast Monroe.
High Wind Warning from 7 AM EST /6 AM CST/ to 10 PM EST /9 PM
CST/ Friday for Bledsoe-Bradley-Hamilton-Marion-McMinn-
Meigs-Northwest Monroe-Rhea-Sequatchie-West Polk.
VA...High Wind Warning from 10 AM Friday to 4 AM EST Saturday for Lee-
Russell-Scott VA-Washington VA-Wise.
&&
$$
SHORT TERM...DH
LONG TERM....SR
AVIATION...BW
Area Forecast Discussion
National Weather Service Pueblo CO
333 PM MST Thu Mar 2 2023
.SHORT TERM...(This evening through Friday)
Issued at 331 PM MST Thu Mar 2 2023
Key Messages:
1) Light, briefly moderate, snow across the southeast plains will
end early this evening.
2) Light snow showers return to the central mountains Friday
afternoon, and potentially the Palmer Divide late.
Latest radar imagery showing snow continuing to develop across the
southeast plains, along with scattered showery development over and
near the mountains. Dry advection has really helped to limit overall
coverage and intensity wit any snow today, and expect that trend to
continue through early evening. The snow across the southeast
plains, which is already quickly diminishing, will continue to
diminish while any remaining scattered snow also quickly diminish
early this evening. Limited additional impacts expected and with
this expected trend, have decided to cancel the remaining winter
weather headlines this afternoon.
Dry weather tonight into Friday morning, though increasing westerly
flow will help return snow showers to the central mountains Friday
afternoon. Relatively mild conditions likely across the plains on
Friday, with RH values expected to fall in the 15 to 20 percent
range in spots in the afternoon. At this time, winds don`t appear
overly strong during that time though. Potential for showery
development across the Pikes Peak region and Palmer Divide late,
though stronger ascent/focus appears to be just to the
north/northwest.
.LONG TERM...(Friday night through Thursday)
Issued at 331 PM MST Thu Mar 2 2023
Long term AFD:
Key messages:
1) Snow showers will be possible over the higher terrain, as well as
rain/snow over the plains for areas mainly north of Highway 50,
tomorrow night through early Saturday.
2) Fire weather concerns will be widespread over the plains on
Sunday afternoon. There could also be fire weather over portions of
the southern plains Monday afternoon.
3) A storm moving over the region through the mid part of next week
has the potential to bring significant amounts of snow to southeast
Colorado, especially over the mountains.
Detailed discussion:
Tomorrow night through Saturday...
Troughing with a weak open wave is going to propagate over the
region from Friday through early Saturday. With this disturbance,
will be a chance of snow over the higher terrain, Palmer Divide, and
possibly snow, or a rain/snow mix, over portions of the plains,
mainly north of Highway 50. A cold frontal passage will occur during
early Friday evening after an associated surface low pressure ejects
out over the plains around the Arkansas River and then transitions
southeastward. The consensus with the timing of this is relatively
similar with all of the higher resolution models, although the HRRR
does have the winds beginning to switch northerly over El Paso
County a little sooner than some of the other models, right around 5
PM. The better chance of snow will be over the Palmer Divide, given
the northerly wind component at the surface, with some upsloping.
There will be some lower stratus forming over much of the plains by
later in the night and into the morning on Saturday. When analyzing
the lastest soundings, there is not a lot of lift showing up in the
models for Colorado Springs until the later part of the morning.
Some of the soundings display a relatively shallow moisture layer
that is below the DGZ with relatively drier air aloft, therefore it
is possible that some of the precip could be in the form of light
freezing drizzle, especially on the northern side near Monument.
Lows will be dropping into the upper teens to low 20s for most of
the plains tomorrow night. It will also get quite cold with colder
air aloft moving over and then clearing out over some of the higher
terrain towards the early morning hours, with lows generally getting
down into the single digits, and even some values below 0F for the
highest mountain valleys and particularly in the upper Rio Grande
River valley. On Saturday, clearing will occur by later in the day,
with any lingering light snow over the peaks and some of areas of
the plains north of Highway 50 ending by around noon or shortly
thereafter. Temperatures will be on the cooler side, but approaching
the seasonal average for most locations for highs on Saturday.
Sunday through Monday...
Upstream, a longwave trough over the western states is going to
continue to slowly approach the region, and this will allow for a
tightening of the pressure gradient and increasing winds out of the
southwest. These downsloping winds, along with a relatively drier
airmass moving in over Colorado is going to cause for there to be
widespread critical fire weather conditions over much of the plains
for the afternoon hours on Sunday. It will also allow for
temperatures to adiabatically warm up for the lower elevations, with
highs topping out in the upper 60s to low 70s for much of the
plains, and also slightly above the seasonal average for the upper
Arkansas River Valley and San Luis Valley. On Monday, as the
longwave trough nears, the airmass will begin to cool and become for
modified, so relative humidity values will not be quite as long, and
there will only be some areas of spotty critical fire weather
conditions over portions of the southern plains. High temperatures
on Monday will also be closer to average for the lower elevations
and a cold frontal passage by later in the day will help to further
cool the plains by late Monday evening. There will also be some snow
beginning to move in over the central mountains.
Tuesday through Thursday...
Ensembles and deterministic models alike are in relatively close
agreement that there will be a deepening trough beginning to move in
over the region at this period in the forecast. However, there
noticeable differences with the timing, progression, and
amplification of this trough as it moves over Colorado. The ECMWF
has the trough much more amplified, with an associated major
shortwave propagating over Colorado later in the day on Tuesday
through early Wednesday, with a low pressure undergoing cyclogenesis
as it moves out over the plains on by later in the day on Wednesday,
and wrap around moisture providing lingering snow showers over areas
of the plains into the early morning hours on Thursday. The GFS has
a much more different take on what the progression of this longwave
trough will do, with the trough becoming more flattened and zonal,
and only a weak perturbation in the trough providing a chance of
snow over the plains by later in the day on Tuesday, and again on
Wednesday. The GFS also has most of the precip confined to the
northern half of the CWA, whereas the ECMWF drops the precip further
south, with higher QPF showing up over the Raton Mesa region. The
Canadian model parallels more with what the GFS is showing.
Looking at EPS and GEFS anomalies, there is a of a lower
anomalies northward within the trough of what the GEFS is displaying
in comparison, so it could be having more of a difficult time
resolving the progression of this trough. It is important to note
that this is far out in the forecast, and there is still a lot of
time for things to change, but if the European ensembles and
deterministic models verify, there could be potentially much more
widespread snow and higher impacts to southeast Colorado during the
mid part of next week. -Stewey
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 331 PM MST Thu Mar 2 2023
VFR conditions and dry weather are expected across all of the TAF
sites this period. Isolated light showers are possible early this
evening, however, don`t expect any big impacts across the terminals.
Generally lighter winds are expected across the TAF sites tonight
into Friday morning, with steadier south southeast winds returning
Friday afternoon at COS and PUB and west southwest at ALS. Potential
for isolated snow showers to develop late Friday afternoon near COS
but at this time, think the development will stay just to the north
of the terminal.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RODRIGUEZ
LONG TERM...STEWARD
AVIATION...RODRIGUEZ
AREA FORECAST DISCUSSION
National Weather Service Charleston WV
928 PM EST Thu Mar 2 2023
.SYNOPSIS...
Strong low pressure system will affect the area late tonight
through Friday night. Mainly dry weather expected this weekend.
Another system brings a cold front with showers Monday night.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 925 PM Thursday...
Made some additional tweaks to lower temperatures further where
some clearing of upper level cloudiness has taken place this
evening, mainly Charleston and points northeast. As additional
cloud cover moves in should see radiative cooling slow through
the remainder of the night.
As of 620 PM Thursday...
Lowered temperatures a couple degrees this evening to be more in
line with observed trends.
Also made some minor modifications for areas favored for cold air
damming during the day Friday. Generally expect marginally sub-
freezing temperatures to work into extreme eastern Randolph, and
portions of eastern Pocahontas County for much of the day as low
pressure approaches from the west. Along the highest ridges, moist
upslope could also yield some subfreezing temperatures with stout
flow just off the deck struggling to erode out these stable pockets.
A stout (+10C) warm nose should yield liquid hydrometeors impinging
on sub-freezing surfaces, however, the extreme nature of the warm
nose and marginal nature of any freezing temperatures, combined with
antecedent warm ground conditions will likely limit any minor ice
accumulations to trees and lines. Given very limited areal extent,
and limited potential for impacts, do not plan to hoist any winter
highlights at this time.
Finally, an important note about messaging wind impacts for
tomorrow:
There is still some uncertainty as to how much momentum is able
to be transferred to the surface with the presence of very
strong low level warm advection with a substantial low level
inversion. Typically in warm advection, WRF based (NAM) and HRRR
tend to overdo bringing winds to the surface, and think this is
the case, at least in areal extent, if not speeds. Would
generally expect some localized down gliding off the higher
terrain to approach warning level - if this occurs it would
likely be quite localized culminating in a hydraulic jump, with
surface winds significantly lighter downstream. Think the
overall message with a wind advisory adequately covers the
expected outcome while we are warm advecting.
The most significant wind impacts however, will likely come
from a narrow line of showers/thunderstorms and cold advection
immediately behind it before winds aloft begin to weaken. These
should have good potential for near full value mix down of top
of the boundary layer winds. These will likely be addressed with
severe thunderstorm warnings, and would not be surprised to see
some enhanced tags for wind speeds with some of these.
As of 215 PM Thursday...
For much of the remainder of today/tonight, cloudy but mild
conditions, with frontal boundary stalled out along our southern
border. This front will lift back north as a warm front early Friday
as a strong low and upper shortwave moves northeast towards the
Great Lakes region out of the south central U.S. Strong pressure
gradient and winds aloft will result in gusty winds across the CWA,
and have elected to expand the wind advisory outside of the
mountains. PW values will soar to around 1.3 inches with the strong
southerly flow, and did elect to hoist a ffa for parts of se ohio
and northeast KY. There is the possibility for a period of a wintry
mix including freezing rain across the higher terrain Friday,
depending on how cold surface temperatures are able to get tonight,
with moist SE upslope flow over any colder air at surface. But think
risk is pretty low/brief, and have no plans for winter headlines.
SPC has expanded the slight risk across southern/western zones of
the CWA. This appears to be yet another low cape/high shear type
event, with the potential for the aforementioned strong winds aloft
to come to the surface with any convection, and the possibility for
tornadoes, owing to low LCL heights/turning of winds in lower
levels. At least some small hail is possible, but any large hail
will really depend on how well developed/tall a storm can get, which
storms should generally be rather low topped in this scenario. Thus,
damaging winds are the primary threat.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 130 PM Thursday...
Starting this period the potent low will be forecast right off
the western side of our CWA border heading northeast. The low
level jet will still be in place promoting the possibility of
winds mixing down up to 40mph+ although soundings indicate
strong inversions in the boundary layer along with virtually no
instability. This will make it very difficult for winds to be
drawn down unless certain areas have winds below the inversion,
therefore we cannot rule out widespread strong winds lasting
into the late morning on Saturday. Other than that,
thunderstorm activity will be diminishing along with any
flooding potential as precipitation tapers off from south to
north through the morning as the cold front occludes and slides
through the area. On the tail end of this system, rain may
changeover to snow in the highest peaks and ridges in the
northeast mountains although accumulations will be very light,
if any. The rest of Saturday and Sunday is forecast to be dry
and around seasonable.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 130 PM Thursday...
High pressure gives most of Monday dry weather although
precipitation chances start to rise as high pressure drifts off
to the east allowing a weak system to approach the area from
the west. This system will drag through a weak frontal boundary
which will bring some rain showers to the area with decent
chance POPs (on the high end) from late evening through Tuesday
afternoon. A short warming trend will last from Monday and
Tuesday then temperatures will sink back down to around average
for this time of year. All long range models agree on this
solution, therefore accepted blended guidance. The Canadian and
EURO both have a disturbance to our south on Wednesday, however
the GFS does not. Models start to diverge greatly thereafter so
decided to trim back some POPs from central guidance to show a
fairly dry day on Wednesday except to our southern most portions
of WV and southwest VA representing the Canadian and EURO.
Also, left most of the area dry for Thursday except for the
northeast mountains due to models showing nothing but the
mountains having chances for precipitation.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
As of 620 PM Thursday...
VFR conditions are expected through early Friday morning. A potent
storm system will approach early Friday morning bringing rain, gusty
winds, and low level wind shear to all terminals. Northwest of the
higher terrain, substantial downslope will yield a dry period for
BKW/CRW and perhaps HTS heading into the afternoon while rain
continues across the north. A significant convective line is then
expected to cross in the late afternoon/evening. While limited
instability may yield more showers than thunderstorms, they will
nonetheless be able to transport very strong winds to the surface.
For the western terminals where convection arrives prior to 00Z,
have included a PROB30 group for near severe level gusts.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SATURDAY...
FORECAST CONFIDENCE: High.
ALTERNATE SCENARIOS: Timing of precipitation and associated
restrictions may vary from forecast.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE FRI
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11
EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H M
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 00Z SATURDAY...
IFR conditions are possible in continuing showers and storms
Friday night.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Wind Advisory from 7 AM Friday to 7 AM EST Saturday for
WVZ005>011-013>020-024>034-039-040.
Wind Advisory from 7 AM Friday to 1 PM EST Saturday for
WVZ515>526.
OH...Flood Watch from 4 AM EST Friday through late Friday night for
OHZ066-067-075-076-083>087.
Wind Advisory from 7 AM Friday to 7 AM EST Saturday for OHZ066-
067-075-076-083>087.
KY...Flood Watch from 4 AM EST Friday through late Friday night for
KYZ101>103.
Wind Advisory from 7 AM Friday to 7 AM EST Saturday for
KYZ101>103-105.
VA...Wind Advisory from 7 AM Friday to 7 AM EST Saturday for VAZ003-
004.
&&
$$
SYNOPSIS...SL/JZ
NEAR TERM...JP/SL
SHORT TERM...JZ
LONG TERM...JZ
AVIATION...JP