Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/28/23
Area Forecast Discussion
National Weather Service Amarillo TX
655 PM CDT Mon Mar 27 2023
...New AVIATION...
.SHORT TERM ...
(This evening through Tuesday night)
Issued at 257 PM CDT Mon Mar 27 2023
Outside of breezy winds this afternoon through this evening,
fairly quiet weather is expected through Tuesday night. A cold
front will cool down temperatures and highs tomorrow will be in
the 50s. Outside of a small chance for a stray shower in the
northern OK Panhandle later today, dry conditions will persist.
So far this afternoon, southerly to westerly winds continue across
the Panhandles with gusts up to 25 to 30 mph across the CWA. Some
scattered cumulus is beginning to develop and move eastward across
the Oklahoma Panhandle at the time of this writing. KAMA radar is
starting to pick up on some very light returns associated with
these clouds and they could produce some very light precipitation
later on this afternoon/evening.
Based on the 27/18z RAP H500 mb analysis, a shortwave trough is
moving across central CO and entering western KS early this
afternoon. This feature is aiding in developing the clouds
mentioned above across the OK Panhandle into western KS. Just
enough PVA at the base of the shortwave may move over the far
northern OK Panhandle. Some mid level moisture looks to remain
over this area when looking at forecast soundings, so some light
precipitation may fall across this area this evening. Main
limiting factor would be the dew point depressions at the surface,
which may be too large for any precip to reach the surface. Either
way, have kept low end mentions of PoPs across this area to
account for the possibility. A cold front will move across the
Panhandles later this evening and northerly winds will prevail
behind the front. H850 temperatures behind the front will fall
down to near or just below 0 C tonight. Below freezing
temperatures are expected area wide and some locations in the
north may drop down into the lower to mid teens. Southerly winds
will return tomorrow afternoon and the cooler air will begin to
retreat to the north and east. Highs will be cooler tomorrow, with
highs in the 50s, and will be well below average for late March.
A 45 to 50 kt low level jet will form over the Panhandles on
Tuesday night and breezy winds are expected heading into Wednesday
morning.
Muscha
&&
.LONG TERM ...
(Wednesday through next Sunday)
Issued at 257 PM CDT Mon Mar 27 2023
Key points: The main area of concern for the long-term will be high
wind and fire weather on Thursday and Friday. A secondary cause
for concern is severe weather potential on Thursday in the east,
but there are uncertainties that lower confidence in it occurring
in our area.
Details: Heights aloft will be rising on Wednesday ahead of a large
West Coast upper-level trough. Highs will largely be in the low to
mid-70s across the area with breezy southwesterly winds. A cold
front pushes into southwest Kansas Wednesday evening, with NAM being
the most aggressive by pushing it into the northern Oklahoma
Panhandle. The models have been too timid with cold fronts pushing
south lately, so won`t be surprised if we ultimately see the cold
front push through the Oklahoma Panhandle. It would still be
unimpactful aside from some cooler lows for those behind the front.
Lee cyclogenesis will begin Wednesday night off to the northwest in
response to the approaching upper-level trough, intensifying in the
afternoon, culminating in a sub-1000mb surface low. The surface
pressure gradient will tighten, resulting in 20-30 mph sustained
southerly winds across most of the area Thursday, with 30-35 mph
southwesterly winds in the northwest.
A 700mb jet will move through the area in the afternoon, and
forecast soundings show that tapping at least into that layer
shouldn`t be an issue for most. The area of greatest concern for
winds is in the northwest, where mixing is expected to be deepest,
perhaps up to 600mb. Additionally, the northwest will be in the
right exit region of the 500mb jet streak, introducing subsidence
which should help bring some very strong winds aloft down.
Currently forecasting wind gusts to reach or exceed 55 mph in that
area.
Later in the day, while the wind and fire threats are ongoing,
severe weather may join the mix. The main question right now is
about where the dryline will be. Currently, most guidance shows low
to mid-50 dew points will hang on in the southeastern counties. GFS
has been trending toward higher dew points, with 12z GFS bringing in
upper-50 dew points. In any case, forecast soundings show that the
cap may erode by 7 pm, but with weak 0-3km lapse rates, instability
should stay below 1000 J/kg. Between the modest instability and the
idea that convective initiation will likely occur in the eastern
half of the Texas Panhandle, confidence isn`t high that storms will
be able to strengthen to severe threshold before moving out of the
area. However, won`t rule out a severe thunderstorm. Will monitor
trends as the severe weather threat would increase if the dryline
trends west.
20-30 mph sustained winds will remain through the evening, and
combined with the subsidence of the right exit region, some areas
could stay mixed post-sunset. If this scenario does pan out,
strong wind gusts could continue because 700mb winds are expected
to strengthen in the evening.
A tight pressure gradient will remain for the Panhandles Friday,
resulting in 30-35 mph sustained winds in the southern half of the
Texas Panhandle. 700mb winds will strengthen in the afternoon, and
again, we should be able to mix up to or beyond that layer. We will
still be seeing subsidence associated with the jet streak, but
this time with the left entrance region. Therefore, wind gusts up
to or exceeding 55 mph will be possible in the southern half of
the Panhandles.
The trouble-making system will move out of the Plains on Saturday
and we`ll return to quiet weather. Some models are hinting at a
shortwave moving through the area at sometime on Sunday. However,
there may not be enough time between systems to get sufficient
moisture return for a chance for precip.
Deterministic models, backed up by their respective ensemble means,
are suggesting another upper-level trough will dip down into the
Western US on Tuesday. This could produce some kind of weather later
next week.
Vanden Bosch/Goehring
&&
.AVIATION...
(00Z TAFS)
Issued at 644 PM CDT Mon Mar 27 2023
For the 00Z TAFs, a cold front will move south of KAMA by the
beginning of this cycle with gusty north winds to around 40 knots
for a few hours this evening at the terminal sites. An Aviation
Weather Warning is in effect until 04Z for KAMA. In addition,
areas of blowing dust will accompany this front, resulting in
locally reduced visibilities to around 5 miles at times early this
evening. Winds will diminish late tonight, then become southeast
to south Tuesday afternoon.
02
&&
.FIRE WEATHER...
Issued at 257 PM CDT Mon Mar 27 2023
Thursday, fire weather concern will be greatest in the northwest.
RH values are forecast to be in the upper single digits. Combined
with 30-35 mph sustained southwesterly winds, RFTI could be as high
as 8 in Cimarron county. Wind gusts could reach or exceed 55 mph.
Fire weather could continue through much of the evening as winds
will only weaken to 20-30 mph and RH values remain below 15%.
Friday, the concern shifts into the southern half of the Texas
Panhandle. 30-35 mph sustained westerly winds are expected with RH
values in the upper single digits. Currently forecasting RFTI values
of 7 to 8 for that area. Wind gusts could reach or exceed 55 mph.
&&
.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX 24 55 34 73 / 0 0 0 0
Beaver OK 21 53 34 72 / 10 0 0 0
Boise City OK 16 51 34 71 / 0 0 0 0
Borger TX 25 57 36 76 / 0 0 0 0
Boys Ranch TX 23 56 33 75 / 0 0 0 0
Canyon TX 24 56 33 73 / 0 0 0 0
Clarendon TX 28 56 33 73 / 0 0 0 0
Dalhart TX 19 52 30 72 / 0 0 0 0
Guymon OK 19 53 33 72 / 0 0 0 0
Hereford TX 23 57 32 74 / 0 0 0 0
Lipscomb TX 23 53 33 73 / 0 0 0 0
Pampa TX 24 54 33 73 / 0 0 0 0
Shamrock TX 28 56 31 71 / 0 0 0 0
Wellington TX 30 56 32 71 / 0 0 0 0
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...Red Flag Warning until 8 PM CDT this evening for TXZ001-006-011-
016.
OK...Red Flag Warning until 8 PM CDT this evening for OKZ001.
&&
$$
SHORT TERM...05
LONG TERM....52
AVIATION...02
Area Forecast Discussion
National Weather Service Billings MT
244 PM MDT Mon Mar 27 2023
.DISCUSSION...
Tonight through Tuesday...
Radar showed a few convective snow showers along the NE Bighorns
this afternoon, otherwise the snow had stopped across the area,
with low clouds breaking up. SREF kept the airmass unstable from
700-500 mb tonight into Tuesday under cyclonic flow. The
instability will support a few evening snow showers over the
Beartooths/Absarokas and NE Bighorns. Otherwise, energy moving
through the cyclonic flow will push a back door cold front into
the NE zones overnight with a 20-30% chance of snow for areas from
NE Musselshell County ESE through KMLS and KBHK. The probability
for greater than an inch of snow for these areas was less than
10%. HRRR also suggested patchy fog from around K3HT to KBIL to
KSHR E, so added this to the grids through early Tuesday. Gusty
SSW winds will develop at KLVM and Nye late this evening as the
pressure gradient tightens up. However the gradient will not be
very strong and 700 mb winds will only be 20 kt based on the
NAEFS. Thus, kept wind speeds sub-advisory and will continue the
wind chart for 50 mph winds for KLVM. A 20-30% chance of snow will
develop over and near the mountains Tue. afternoon due to low-
level upslope flow and moisture advecting in from the W.
Lowered temps below the NBM tonight and Tuesday due to the heavy
snowpack. Arthur
Wednesday through Monday...
Main forecast concerns are periods of snow late Wednesday into the
weekend.
Overall forecast confidence is high through Friday. WPC Cluster
members are showing overall good agreement in the large scale
pattern over the western CONUS. Consulting NBM probabilities for
greater than 2 inches of snow, probabilities are indicating high
chances (50-80%) of exceeding 2 inches of snow over the
mountains/foothills areas of south central Montana, including the
Absaroka/Beartooth, Pryor, and Bighorn Mountains. The probability
for exceeding 6 inches is very low (20%) and mainly confined to
higher elevations above 8 kft. Consulting ECMWF Ensemble members,
the timing for the onset of snow at Red Lodge looks to be between
12 and 18Z on Thursday with an ending time of around 18 to 00Z
Friday. Expect some travel impacts from this light snow event.
Flow aloft looks to transition to more zonal late in the weekend
with temperatures moderating just a bit. Saturday looks to be the
warmest day with a chance (~50%) for highs to exceed 50 degrees
at Billings. With the possibility for these warmer temperatures,
this may create increasing runoff into area rivers, possibly
increasing the potential for ice jams. The next chance for
precipitation looks to arrive later Saturday into Sunday with the
potential for mountain snow and some rain at times in the lower
elevations.
&&
.AVIATION...
Expect areas of MVFR ceilings into this evening, otherwise
conditions will be VFR. A 20-30% chance of snow will move into
KMLS and KBHK by 03Z and move E of the area by 12Z. MVFR/IFR
conditions are possible with the snow. Patchy fog will develop
overnight and persist into Tuesday morning. SSW surface winds will
increase at KLVM tonight with gusts to 40-45 kt, and diminish
Tue. morning. Expect areas of mountain obscuration this evening
and on Tuesday. E flow will develop Tue. afternoon, bringing in
MVFR/IFR ceilings. Arthur
&&
.PRELIMINARY POINT TEMP/POPS...
Tue Wed Thu Fri Sat Sun Mon
-----------------------------------------------------------
BIL 013/030 017/035 024/036 024/044 031/050 030/045 024/041
01/E 10/E 26/S 31/B 01/B 34/S 44/S
LVM 015/037 020/037 027/037 022/045 030/048 028/041 022/038
02/S 11/E 47/S 21/B 13/O 55/S 55/S
HDN 009/033 014/039 018/036 021/043 023/051 026/046 021/043
01/B 10/B 26/S 51/B 01/B 34/O 44/S
MLS 018/030 015/044 025/041 022/043 028/055 033/049 026/042
20/E 00/U 12/S 21/B 00/B 22/O 23/S
4BQ 018/034 017/045 025/043 024/041 026/056 032/048 027/044
00/B 00/B 13/S 52/S 00/B 22/R 33/S
BHK 011/025 007/037 019/037 016/036 021/051 027/046 022/039
30/B 00/U 12/S 21/B 00/U 22/S 23/S
SHR 005/031 012/037 018/035 019/037 018/046 023/040 017/037
00/B 10/B 16/S 72/S 00/B 23/S 44/S
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Corpus Christi TX
835 PM CDT Mon Mar 27 2023
...New AVIATION...
.SHORT TERM...
(Tonight through Tuesday night)
Issued at 303 PM CDT Mon Mar 27 2023
Key Messages:
- Patchy sea fog expected through the night
- Marginal Risk of Severe Weather this afternoon across the
Victoria Crossroads
- Marginal Risk of Severe Weather on Tuesday for the southern
half of the CWA
MSAS analysis reveals a frontal boundary stalled out to the north of
the CWA. This feature has been sitting there through much of the day
as upper level forcing has been lacking to push it further south.
Meanwhile, onshore flow continues to funnel low level moisture
into the region. This morning`s KCRP 12Z sounding showed PWATs of
0.86". The few GOES TPW pixels that can be seen through the dense
stratus indicates those numbers have risen to near 1.45" across
the Coastal Bend. A few spotty showers can be seen on radar as of
writing. Would expect a slight increase in cover, generally east
of Highway 281, with potentially an isolated thunderstorm mixing
as instability continues to climb. In addition, patchy fog has
been lingering along the coast through the day. Visibilities have
generally ranged from 2- 4 miles with a few spots dropping below 1
mile at times. This trend will continue through this evening with
SREF probs adding higher confidence to dense fog developing
overnight.
As we head into the overnight period, an upper level shortwave will
provide the forcing need to push the front further south. The front
looks to be across our northern tier of counties by 12Z and pushing
offshore by mid day. SPC currently has the majority of South Texas
in a Marginal Risk for Severe Weather tomorrow. It looks like we
have potentially 2 rounds of showers and storms:
1) Showers and thunderstorms will be possible during the morning
hours as low level forcing is increased maximized the boundary
along with support aloft via mid to upper level shortwaves.
Sufficient instability (2500+ CAPE), shear (40-50 knots), and mid
level lapse rates near 8C/km would support a hail and winds
threat. A few select soundings do show over 1000 DCAPE with a
rather moist low level profile. Recent runs of the HRRR have been
inching further south towards Deep South Texas with this first
round of storms. This is similar to where the 12Z HREF shows the
highest probabilities for heavy rainfall. This round of activity
looks to clear the region during the early afternoon hours
2) Isentropic lift around the 305K level will keep some moisture in
place across the region. During the evening and overnight hours,
another shortwave will rotate through the region as the RRQ of a jet
streak passes by. This upper level forcing, along with some elevated
instability, should be enough to encourage another round of
convection. Any convection that does develop will fizzle out at our
support leaves the area during the early morning hours Wednesday.
After a mild night tonight, we are in store for a slight cool down
behind the front. Highs on Tuesday will struggle to reach the mid 70
with lows falling into the mid 50s inland overnight.
&&
.LONG TERM...
(Wednesday through next Sunday)
Issued at 303 PM CDT Mon Mar 27 2023
Key Messages:
- Chance of showers continues through Wednesday, then isolated
showers or thunderstorms will be possible at times across the Rio
Grande Plains the remainder of the week.
- Temperatures more seasonal Wednesday then warming back up to
above normal the rest of the week.
- Minor coastal flooding and moderate to high rip current
risk possible Wednesday and Thursday.
Sufficient moisture behind Tuesday`s front will continue into
Wednesday with models indicating a weak isentropic upglide pattern
developing. Combined with an embedded upper level short wave in a
quasi-zonal west flow aloft moving east across S TX Wednesday, will
contribute to scattered showers on Wednesday. MOdels indicate some
drying in the mid levels by Wednesday afternoon with the rain
diminishing across the area.
Overnight Wednesday, low level flow across the Rio Grande Plains is
progged to strengthen from the south and southeast. This will
strengthen isentropic lift across the western CWA and will combine
with yet another short wave aloft to bring a slight chance to chance
of showers.
At the surface, a southeast to south flow will strengthen across S
TX through Thursday, bringing moisture and warmer temperatures back
into the area through the remainder of the week.
A mid level high pressure system centered along the coast of Mexico
is progged to shift east toward the Yucatan as an upper low swings
across the Midwest Thu/Fri. This will bring a long wave trough
toward TX the latter part of the week which will push a weak cold
front and/or develop a surface trough across S TX Saturday. This
will lead to a slight chance of showers, possibly a thunderstorm or
two by the weekend.
A weak to moderate northeast then east flow Wed into Thu may lead to
minor coastal flooding and/or moderate to high rip current risk.
Confidence is low that this will occur as swell periods are progged
to be around 6-7 seconds, but the NWPS Rip Current Probability shows
an increase in swell heights. In addition, P-ETTS shows an increase
in tide levels Wed/Thu.
&&
.AVIATION...
(00Z TAFS)
Issued at 828 PM CDT Mon Mar 27 2023
Expect a mixture of MVFR/IFR ceilings tonight through early
Tuesday morning, along with weak onshore flow. Expect areas of
fog with MVFR/IFR visibilties near the immediate coast. Scattered
showers and isolated thuderstorms, with brief IFR
ceilings/visibilities, are expected to develop from north to south
across South Texas along and in advance of a cold front, during
the approximately 10-16z Tuesday period. Afterward, predominate
MVFR ceilings/VFR visibilities, with moderate/breezy
north/northeast wind, which will continue until the end of the TAF
period.
&&
.MARINE...
Issued at 303 PM CDT Mon Mar 27 2023
Patchy sea fog is expected to linger along the coast through this
evening with visibilities generally ranging from 2-4 miles.
Another round of patchy fog is possible late tonight ahead of an
approaching cold front. A cold front will move across the coastal
waters Tuesday and bring a chance for showers and thunderstorms.
Northeast winds will increase to around 20 to 25 knots behind the
front. A few gusts to gale will be possible across the offshore
waters. Winds will begin to relax through the morning hours
Wednesday. Moderate northeast winds will continue over the Gulf
waters Wednesday along with a chance of showers. The flow will
become easterly Wednesday night and southeasterly by Thursday.
Moderate to at times strong onshore flow is expected through the
remainder of the week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 68 76 58 70 / 30 40 50 40
Victoria 64 74 56 69 / 40 20 30 30
Laredo 67 73 57 67 / 50 60 40 30
Alice 65 76 56 69 / 30 40 50 40
Rockport 66 77 60 72 / 30 30 40 30
Cotulla 65 76 56 69 / 40 40 30 20
Kingsville 67 76 58 70 / 20 50 50 40
Navy Corpus 67 76 62 72 / 30 50 60 40
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory from 10 AM to 7 PM CDT Tuesday for GMZ231-
232-236-237.
Small Craft Advisory from 10 AM to 10 PM CDT Tuesday for GMZ250-
255.
Small Craft Advisory from 10 AM Tuesday to 3 AM CDT Wednesday
for GMZ270-275.
&&
$$
SHORT TERM...TC
LONG TERM....TE
AVIATION...WC/87
Area Forecast Discussion
National Weather Service State College PA
1155 PM EDT Mon Mar 27 2023
.SYNOPSIS...
Drier and cooler conditions move in for Tuesday. A cold front
will cross the region Wednesday night with rain and snow showers
followed by cold conditions on Thursday. The weekend looks
milder but unsettled with widespread showers. No fooling, April
will arrive with rain, a threat of storms, and a big drop in
temperatures as a cold front sweeps through.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Precip has largely moved east of the area. Clouds linger mainly
across the NW and Laurels. Some drizzle or light snow flurries
are possible in these areas, but most spots will stay dry.
Temps will dip to mins in the upper 20s across the north and
mid to upper 30s in the SE Valleys.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Zonal flow and the passage of a SW-NE ridge of sfc high
pressure brings mainly dry and cooler than normal temperatures
for the bulk of the time Tuesday and Wednesday. Some waviness in
a zonal upper level pattern may produce a few showers on
Tuesday night. Any such accumulation would be minimal with rain
across the south and perhaps some snow farther north.
A cold front will bring a brief period of precipitation
Wednesday afternoon and evening for most of the region. With a
deep layer of steep lapse rates ahead of the strong front, a
linear band of heavier rain and snow showers is possible,
potentially making for slick road conditions north of I-80 if
it comes in towards/after dark. Temps drop off quickly in the
wake of the cold front with winds gusting to 35 or 40 mph in the
northwest mountains. Winds stay up overnight and Thursday
morning will be the coldest of the week with temperatures near
20 up north and near freezing in the southeast.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
In the wake of the cold front, expect a brief cool down, with
high temperatures on Thursday running a few to several degrees
below normal. It will be quite dry as well with plenty of
sunshine. RH values will dip into the 20s percent Thursday
afternoon and could even drop into the teens. Although winds
will be lighter, there may still be gusts above 20 mph
especially through the Susquehanna valley.
High pressure will slide off the East Coast Thurs night, with a
southerly flow developing. This should lead to significantly
milder temperatures for the end of the week and into the first
part of the weekend. Current guidance supports temperatures in
the 50s and 60s on Friday with an additional 10 degrees added to
those highs on Saturday afternoon. The realization of such warm
temperatures on Friday and Saturday will be dependent on the
extent of precipitation during the day and how quickly a strong
cold front moves through. There remains some uncertainty in
timing and extent of precipitation, but confidence is high in a
widespread soaking rainfall and mild temperatures.
Widespread stratiform rain during the Friday and Friday night
timeframe will precede the arrival of a strong cold front. As
the front sweeps through, timing will be important for the
potential threat of severe weather. Arrival in the afternoon
during peak heating on Saturday would lean toward more storms
and perhaps higher severe weather chances. Earlier/later arrival
in the morning or late evening would limit the severe threat,
but it bears watching.
Ahead of and after the cold front sweeps through, expect gusty
winds to develop thanks to a deepening surface low over Quebec.
The wind threat looks formidable with this system and gusts in
excess of 40mph appear plausible for most of the area.
Temperatures will drop of considerably by Sunday with 24 hour
temperature changes forecast to be -20 to -30 by Sunday
morning. High pressure builds in for Sunday, bringing plenty of
sunshine, calmer winds, and gradual warming into the first full
week of April.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
The main focus overnight will be on developing low cigs across
the W Mtns associated lingering low level moisture and an
upsloping northwest flow. Observations at 03Z show a ribbon of
IFR cigs extending from Ohio across the western NY state. The
latest RAP 925mb 90pct RH fields, which align well with this
area, suggest IFR/LIFR cigs over NW Mtns will expand southward
into the Laurel Highlands by around 05Z-06Z. Ensemble prob
charts indicate IFR/LIFR will then remain likely through early
Tuesday morning over the W Mtns. Elsewhere, a downsloping
northwest flow should yield progressively better conditions
downwind (southeast) of the Alleghenies, with VFR conditions
likely across the Susq Valley.
High pressure building in from the Grt Lks should result in
rising cigs/breaking clouds across central PA Tuesday. Model RH
profiles and ensemble probs suggest VFR conditions are likely
across the entire region by afternoon. However, borderline high
MVFR/low VFR cigs appear likely to linger over the NW Mtns
until early evening.
Outlook...
Wed...Evening snow squalls possible, mainly NW Mtns.
Thu...No sig wx expected.
Fri...PM rain/low cigs possible, esp NW Mtns.
Sat...AM showers/reduced cigs possible, then turning windy.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Lambert/Colbert
NEAR TERM...Lambert/Colbert
SHORT TERM...Lambert/Colbert
LONG TERM...Colbert/Banghoff
AVIATION...Fitzgerald
Area Forecast Discussion
National Weather Service Dodge City KS
538 PM CDT Mon Mar 27 2023
...UPDATE TO AVIATION...
.SHORT TERM...(This evening through Tuesday night)
Issued at 338 PM CDT Mon Mar 27 2023
This afternoon, a compact yet intense storm system was moving across
northeast Colorado into adjacent far northwest Kansas and far
southwest Nebraska. RAP analysis was showing very cold 500mb
temperatures with this system -- as cold as -37C in the cold pocket
across the northern Colorado Rockies. This resulted in very steep
lower and mid level lapse rates with surface-based Lifted Indices
right around zero or slightly below zero (upwards of 100 J/kg CAPE)
across some portions of the eastern Colorado High Plains. Showers
continued to develop during the mid afternoon hours across eastern
Colorado into far western Kansas, but observations and RAP analysis
were showing precipitation type as rain southeast of roughly
Cheyenne Wells to La Junta, CO line. As the system continues to move
east, the freezing level will drop across a larger portion of west
central and some portions of southwest Kansas (down to 1000 feet AGL
or lower), supporting dominant precipitation type of snow. Most
areas northwest of a Garden City to La Crosse line should see wet
snow around sunset, but the longevity of the precipitation event as
snow will not be very long, thus no impacts are expected with the
snow -- other than perhaps a couple slick bridges and overpasses as
the sun lowers and precipitation rates are high enough.
Precipitation will end across our forecast area late tonight, around
03 or 04Z. There will be a brief period of fairly strong northwest
wind up until late tonight, but after 05Z or so, winds just about
everywhere will drop to 10 mph or less. As we head into Tuesday,
surface high pressure will be centered across the western half of
Kansas leading to light and variable winds. Temperatures will be
slow to rebound through the 40s, but by late afternoon with some
insolation, we should see afternoon highs top out around 50 to 53
degrees.
.LONG TERM...(Wednesday through Monday)
Issued at 338 PM CDT Mon Mar 27 2023
Sensible weather at the beginning of the Long Term period will be
largely the result of the next big storm system approaching the
western Great Plains Thursday and Friday. In between storm systems
on Wednesday, we will be watching for a sneaky cold front to push
south, thanks to a subtle shortwave trough rotating around the
southern periphery of a larger polar gyre centered across central
Canada. An anomalously cold airmass awaits upstream, so this front
on Wednesday could really disrupt the current temperature forecast.
Latest models today now show a stronger cold front and stronger low
level cold air advection as a result. There will likely be a 35-
degree surface temperature gradient across the front Wednesday
afternoon (30s north of the front across southern and central
Nebraska to around 70 across southern Kansas). The current forecast
calls for a high in the mid 50s along I-70 on Wednesday, but that
could very well be early in the day with falling temperatures in the
afternoon. This is one component of the forecast that will likely
see some continued modification as we get closer to Wednesday
afternoon.
The cold front will reach a terminus some time Wednesday evening
across southwest Kansas. The front will stall out then begin to lift
back north Wednesday night as a warm front, thanks to the
approaching storm out west. The initial southwest flow aloft will
impinge on the High Plains early Thursday with a deep leeside trough
developing as a result. Wind speeds will increase and temperatures
likely will, too, during the night. Most areas may be waking up to
temperatures in the upper 40s to lower 50s along and south of the
Arkansas River Thursday morning.
Winds will only further increase in strength during the day Thursday
as a deep surface low forms within the leeside trough across east
central Colorado-far west central Kansas. Low level Gulf of Mexico
moisture will be increasing out of the south thanks to the intense
low level jet with lower to mid 50s surface dewpoints by late
afternoon across the eastern half of the DDC CWA (along and east of
U283). The latest NBM winds are showing afternoon winds 30 to 40 mph
sustained on both sides of the dryline. Gusts in excess of 50 mph
are looking more and more likely especially along/west of the
dryline where mixing depth will be greater. Blowing dust will be in
the grids where current wind gust forecast is in excess of 45 mph.
The next question centers around probability of severe weather
across south central Kansas east of the dryline. The Day 4 SPC
Convective Outlook has a 15% area including our southeastern
counties, although this may be a bit ambitious, as a capping
inversion due to a fairly robust elevated mixed layer (EML) will be
in play. It would take some intense mid level cold advection to
erode a strong EML as suggested by some of these early model runs.
The latest EPS 500mb height anomaly fields for 00Z Friday show the
greatest negative height anomalies still way out across western
Arizona into Utah, which would certainly support a mid level cold
front well to the west of the dryline late Thursday. It would not be
too surprising to see the next SPC Convective Outlook pull back a
little bit on the 15% risk area given this timing issue and such
strong convective inhibition east of the dryline Thursday evening.
The best forcing for ascent will be coming out across western Kansas
some time early Friday morning, and by that time, the low level wind
field will be veering out too much pushing all the Gulf of Mexico
moisture too far east into southeast Kansas. GEFS and EPS 500mb
anomaly fields for 18Z Friday are in pretty good agreement with
negative height anomaly centered from northwest KS into southwest
NE, so any cold sector precipitation on Friday will be confined to
far northwest KS into western Nebraska. As such, a dry forecast will
continue for west central and southwest Kansas behind this low.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 535 PM CDT Mon Mar 27 2023
MVFR cigs will linger in vicinity of KHYS, KGCK, and KDDC through
early evening as a band of low level stratus shifts eastward across
southwest and central Kansas. Periods of light rain/snow can also
be expected. Otherwise, widespread VFR conditions are expected to
develop overnight and persist through early Tuesday. Northwesterly
winds around 15 to 30kt are forecast to develop immediately behind
a cold front moving through southwest/central Kansas this evening,
then subside overnight.
&&
.FIRE WEATHER...
Issued at 338 PM CDT Mon Mar 27 2023
Along and west of the dryline on Thursday, critical fire weather
conditions are appearing more and more likely as there is high
confidence in both very strong southwest winds and very low relative
humidity. Latest forecast will continue to show minimum afternoon
relative humidity in the 10 to 15% range generally west of Highway 83
to the Colorado border. The SPC Fire Weather Outlook already has a
70% Risk area for Critical Fire Conditions across our far southwest
counties. Placement of the dryline from mid afternoon through early
evening will certainly be very important in how far 3-hr or longer
Critical conditions can extend east/northeast across southwest
Kansas. We will also have to watch the Oklahoma border county areas
Friday afternoon, depending on how far south the cold front will
reach, as south of the cold front Friday afternoon there will likely
be another day of large scale Critical Fire Weather. SPC Day 6
Outlook (Valid Friday) has an even larger area of 70% Critical risk
area encompassing the Texas and Oklahoma Panhandles, bordering on
the Kansas state line.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 22 52 33 67 / 20 0 0 0
GCK 19 51 31 62 / 10 0 0 0
EHA 19 53 35 70 / 0 0 0 0
LBL 20 53 31 70 / 10 0 0 0
HYS 21 51 30 57 / 60 0 0 0
P28 27 54 30 69 / 30 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...JJohnson
FIRE WEATHER...Umscheid
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
258 PM PDT Mon Mar 27 2023
.SYNOPSIS...A potent cold front will bring strong and gusty south
winds to Northwest California tonight. Winds will diminish after
frontal passage early Tuesday morning, however gusty winds will
redevelop by Tuesday afternoon as a compact low approaches from
the northwest. Heavy snow is forecast tonight, generally above
2000 feet, and will impact the region Tuesday through Wednesday.
Colder and drier conditions are forecast for the latter portion of
the week, before another weaker system brings lighter amounts of
rain and mountain snow next weekend.
&&
.DISCUSSION...A surface low has been developing just west of 130W
almost due west of Pt St George and moving NE this afternoon.
This area of low pressure will continue to deepen this afternoon
and evening (down to 992mb) while an occluded surface boundary
moves toward the North Coast. Several higher elevation RAWS have
been reporting gusts around 50 mph this afternoon, while a few
coastal headland sites (KCEC) have reported gusts near 55 mph.
High resolution model guidance continues to indicate a coastal
barrier jet strengthening to 60-70kt late this afternoon into
this evening as the occlusion approaches. HRRR surface gusts ramp
up to 52-63mph across the coastal plain this evening. A high wind
warning for gusts to 60 mph or more for the coastal Humboldt and
for gusts to 70 mph or more for the higher elevations of Humboldt
remains in effect through the late tonight. HRRR and multi-model
blended guidance shows wind dropping off significantly after
frontal passage, between about 2 to 4 AM. Elsewhere, a wind
advisory remains in effect for gusts to 45 to 55 mph, primarily
for the upper elevations and ridges. Portions of the Mendocino and
Del Norte County may also have stronger wind gusts to 60-70mph
and an upgrade to warning may be necessary this evening.
Later this afternoon and evening frontal precipitation moves
onshore. The big challenge of the forecast is the snow levels. For
now it looks like the snow levels will be around 1500 to 2000 as
the heaviest precip moves onshore. These are expected to rise
slightly later tonight everywhere expect Trinity county. This will
limit impacts on hwy 101, but confidence is low on how quickly
snow levels will rise. Confidence is highest that Trinity county
will see significant impacts from the heavy snow, possibly even in
Weaverville. The south southeast slopes where strong winds will
enhance upslope. This will also help to keep snow levels low.
Tuesday is expected to see the rain diminish once the front
moves through and before the showers really start to increase in
coverage later in the day. Tuesday evening and overnight is when
the showers really look to increase and the winds will increase
again as well. There is still some disagreement in how quickly
this low will move down the coast. In general showers look to
taper off through the day on Wednesday. An additional wind advisory
may be needed in Humboldt and Del county depending how quickly
the surface low fills.
Mainly dry conditions are expected with some shortwave ridging in
between systems. Friday is expected to some showers, but these are
expected to be minimal. Saturday another frontal boundary looks to
move onshore, but it will generally be light and snow levels will
be over most of the highway passes. Snow levels may drop Sunday as
the upper level low potentially drops over the area.
&&
.AVIATION...Ceilings have stayed high near 8 kft today allowing VFR
conditions to prevail despite increasing south winds. A front will
sweep across the area early this evening, sharply increasing south
winds along the coast by 1800. Gusty winds will continue to build
this evening reaching as high as 55 mph in exposed areas in Humboldt
and Del Norte Counties. Sustained winds as high as 65 mph at 2 kft
will lead to widespread low level windshear tonight. Light rain will
build in behind the front with ceilings dropping near 4 kft
overnight. Brief IFR conditions are likely in showers.
Despite the storm, mostly VFR is expected until around 0300 Tuesday
morning when MVFR to IFR conditions are possible with falling
ceilings and visibilities, especially in stable inland valleys like
around UKI. Mostly VFR conditions are expected by late morning
Tuesday as ceilings lift and precipitation becomes more showery.
Isolated thunder is possible tomorrow right along shore as showers
lift over the coastal mountains. /JHW
&&
.MARINE...Strong southerly winds will continue to increase this
evening with gale force gusts throughout the waters. Storms force
gusts are expected in the northern outer waters with gusts as high
as 55 kts. Short period seas will increase with the winds reaching
around 14 to 17 feet late tonight.
Storm force winds will ease by early Tuesday, though widespread near
gale to gale force gusts will continue until early Wednesday
morning. Similarly, short period seas up to 15 feet will continue
with the wind, mostly in the northern waters. At the same time, a
mid period swell around 12 feet at 11 seconds will build in the
waters, though current model guidance show it being short lived,
totally decaying by the end of the day Wednesday.
As the storm system lumber south, gentle north winds will arrive
Thursday with seas falling below 6 feet. A weaker system is expected
this weekend with moderate to strong southerly winds returning by
Saturday. /JHW
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
Wind Advisory until 5 AM PDT Tuesday for CAZ101-102.
Winter Weather Advisory until 5 AM PDT Wednesday for CAZ102.
High Wind Warning until 1 AM PDT Tuesday for CAZ103.
High Wind Warning until 5 AM PDT Tuesday for CAZ104>106.
Winter Storm Warning from 5 PM this afternoon to 5 AM PDT
Wednesday for CAZ104>108.
Wind Advisory from 5 PM this afternoon to 5 AM PDT Tuesday
for CAZ107.
Wind Advisory from 6 PM this evening to 5 AM PDT Tuesday
for CAZ108>111.
Winter Weather Advisory from 5 PM this afternoon to 5 AM
PDT Wednesday for CAZ110-111.
Wind Advisory from 8 PM this evening to 5 AM PDT Tuesday
for CAZ112>115.
Winter Weather Advisory from 8 PM this evening to 5 AM PDT
Wednesday for CAZ114-115.
NORTHWEST CALIFORNIA COASTAL WATERS...
Gale Warning until 9 PM PDT Tuesday for PZZ450-455-475.
Storm Warning until 3 AM PDT Tuesday for PZZ470.
&&
$$
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For forecast zone information
see the forecast zone map online:
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Area Forecast Discussion
National Weather Service Goodland KS
1003 PM MDT Mon Mar 27 2023
.UPDATE...
Issued at 1000 PM MDT Mon Mar 27 2023
While very light snow or occasional flurries may persist for
another hour or two.. accumulating snow has ended. As a result,
the Winter Weather Advisory has been cancelled.
&&
.SHORT TERM...(This evening through Wednesday Night)
Issued at 305 PM MDT Mon Mar 27 2023
At the start of the short term period, the latest RAP analysis shows
the CWA with a west-southwesterly flow aloft being under the front
part of an upper air trough that has a positively tilted axis just
to the west of the CWA. Current surface observations as well as
radar imagery shows a surface low slowly traveling across eastern CO
allowing with some stronger winds in the southwestern quadrant of
the CWA with light to moderate snow continuing in areas along and
north of I-70. Forecast models show the axis of the trough passing
over the CWA during the evening allowing for a westerly flow aloft.
At the surface, the Winter Weather Advisory continues through
midnight MDT with the current snowfall continuing. Will monitor this
in case an early cancellation is warranted, but chances for snow
look to end west to east with the movement of this surface low
across the CWA. A Blowing Dust Advisory continues for the
southwestern quadrant of the CWA due to the possible stronger wind
gusts observed which were around 55 mph that caused some blowing
dust within the area. Will monitor this as well in case an early
cancellation is needed if conditions improve, but areas that saw
lesser snowfall have been reporting some blowing dust visibility
reductions. Overnight lows for tonight look to be in the lower teens
to the lower 20s with minimum wind chills near the zero degree mark
in the far western portions of the CWA.
On Tuesday, the front part of a trailing ridge moves over the CWA
during the morning hours as the trough departs to the east. A
generally west-northwesterly flow is seen over the CWA going into
the night as the axis of the ridge stays to the west of the CWA
while an upper air low moves over the coast of northern CA
overnight. A shortwave disturbance is seen over the CWA during the
evening hours as well. At the surface, the southwestern quadrant may
be seeing some elevated fire weather concerns during the afternoon
hours with minimum RH values in the upper teens. Another surface low
is seen in the models in CO allowing for some breezy winds. However,
the quicker southerly winds that look to gust up to around 35 kts in
southern portions of the CWA look to be during the evening and into
the night. Will monitor the timing on these winds in case they start
to coincide better with the driest conditions. Daytime highs on
Tuesday look to range between the middle 40s and lower 50s while
overnight lows are forecasted between the upper teens and upper 20s.
For Wednesday, models forecast the ridge moving more eastward with
the axis reaching over the CWA during the evening hours giving the
CWA a westerly flow aloft. The aforementioned western upper air low
is projected to make its way inland behind the ridge as well. At the
surface, some models show a cooler airmass moving slightly into the
region in the morning with a northeasterly surface flow during this
time that turns easterly during the day as models show the CWA
between a high out over IA and another low over northern NM. Fire
weather does not look to be a concern on Wednesday. Daytime highs
look to be between the upper 30s and middle 50s on Wednesday
followed by overnight lows in the lower 20s and lower 30s range.
.LONG TERM...(Thursday through Monday)
Issued at 115 PM MDT Mon Mar 27 2023
Deep trough will be located over the western CONUS to start the
period. It will move into the central plains on Friday with a cut
off low developing over western Nebraska. Over the weekend will
see more of a zonal flow or weak ridging aloft. Early next week,
another trough digs into the western CONUS with broad
southwesterly flow ahead of it into the plains.
Thursday will be windy, warm and dry, with the potential for
critical fire weather conditions and perhaps blowing dust south of
Interstate 70 in Colorado and Kansas. Highest confidence is in
the fire weather, especially south of Highway 40, where humidity
will drop below 15 percent. Low to moderate confidence at this
time in the wind and blowing dust potential, although furthest
south locations stand to see the best chance of both. Lapse rates
are supportive of the blowing dust, and forecast soundings show a
deeply mixed boundary layer which potentially taps into 40 to 50
mph winds at 2km Thursday afternoon. Highs will be in the 60s and
70s. As the upper low cuts off to the north, the area will
initially be dry slotted. However, wraparound precipitation will
move into the northern parts of the area late Thursday night and
into Friday. Precipitation will be mainly rain showers, but might
see a rain/snow mix at times, especially in the morning. Friday
will also be breezy with potential for northwest winds gusting up
to 40 mph indicated at this time. Temperatures on Friday will cool
off into the 40s and 50s.
The weekend looks dry under the zonal flow. Temperatures will be
slightly above normal on Saturday (60s) and much above normal on
Sunday (60s and 70s). With the warmer temperatures will also be
fire weather concerns. Humidity does drop to under 20 percent
south of Interstate 70 both days. However, wind speeds currently
marginal for critical conditions, with gusts under 20 mph
forecast. If that continues, may see more elevated fire weather
conditions as opposed to critical.
A front slips into the area Sunday night with east to southeast surface
winds forecast on Monday. Temperatures cool slightly with highs
in the 50s and 60s, assuming no clouds. Precipitation chances look
to stay west of the area through Monday night.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1000 PM MDT Mon Mar 27 2023
MVFR ceilings and/or visibilities will prevail at the beginning
of the TAF period. Improvement to VFR is possible overnight..
though any clearing trend may precipitate fog/stratus development
during the pre-dawn hours (08-12Z) Tue morning. VFR conditions and
mostly clear skies will prevail thereafter.. through the day on
Tuesday. 10-15 knot northerly winds will back to the W and
decrease to 7-12 knots overnight becoming variable Tue morning.
Winds will shift to the S-SSW and increase to 15-20 knots during
the latter portion of the TAF period (~21Z Tue at GLD, closer to
00Z Wed at MCK) as surface high pressure over the region
progresses east toward the Central MS River Valley and a surface
trough deepens in the lee of the Rockies.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...Vincent
SHORT TERM...076
LONG TERM...024
AVIATION...Vincent
Area Forecast Discussion
National Weather Service Gray ME
1047 PM EDT Mon Mar 27 2023
.SYNOPSIS...
A low pressure system will bring a mixture of rain and snow
tonight, but with little to no wet snow accumulation expected.
High pressure builds in Tuesday afternoon into Wednesday with
quiet weather. A strong cold front approaches Wednesday night
with gusty winds Thursday.
&&
.NEAR TERM /OVERNIGHT/...
1045 PM Update...Quick, minor update to tighten northern edge of
PoP further and reduce on the northeastern bound over Maine.
Still all rain on surface observations, besides snow up at
MWNObs. Overall the forecast remains well on track with little
change to running forecast thinking. Dew points in the river
valleys have crept above freezing... eliminating accumulation
potential for the most part there. However modeled soundings
indicate wet accums are still on the table elsewhere, though
still keeping the logic that we`ll top out around 1-2" along
peaks and ridges.
805 PM Update...More comprehensive forecast update now that the
aviation forecast is out the door. Primary edits aside from the
usual blending in of obs were to sharpen PoP trends through the
remainder of the evening and the overnight period with dry air
proving to be more stubborn than prior model runs has indicated.
Thus I trimmed PoP along the northern edge of the existing
forecast... except at elevation... and boosted PoP a little bit
toward the Mass border and into the Sunapee region where better
forcing and moisture depth is likely through tonight. At the end
of the day however the snowfall forecast remains about the same
with light amounts up to 1-2" possible in the higher terrain of
southwestern New Hampshire.
640 PM Update...Minor tweaks to T/Td trends. Surface obs still
not indicating precipitation reaching the ground in SW NH.
Previously...
Cirrus continues to spread into the region this afternoon after
a gorgeous morning. With high pressure exiting and sfc temps
pushing towards the mid 50s across the interior, a light sea
breeze has also been observed from mainly Portland south along
the NH seacoast.
This evening, precip from an approaching low pressure system
will onset. With large dewpoint depressions at the surface,
don’t expect any measurable precip to begin for a couple more
hours. Rain is expected initially, with snow mixing in first
across higher elevations of NH. Lower elevations won’t see snow
mix until precip rates pick up and sun goes down. Monitoring a
snowband tool, there are some low chances of deformation precip
bringing steadier rates of snow near the NH/MA border late
evening and around midnight. Continuing to mention very light
accumulations due to warm ground and low snow ratios, with
perhaps an inch at higher elevations of southern and central NH.
Visibility may be more impactful if snow rates do perform well.
North of this area, precip should be fairly light. The mix of
rain/snow may also be more widespread as rates elsewhere may not
allow as much dynamic cooling.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
All precipitation should lose intensity come early Tuesday
morning. Just a slight trough will remain in wake of the low,
allowing some spotty rain showers to continue near the coast and
interior.
Tuesday AM will be in stark contrast to this morning, where it
should be fairly damp and cooler through the morning. Temp
trends do warm up, but it should run a couple degrees off normal
for the day, remaining mostly cloudy. With remaining moisture
and the heating, could see a few air mass rain showers develop
in the afternoon. But these will be largely driven by steep low
level lapse rates which aren’t too high confidence at this
point. The better chance for these may be where breaks in clouds
develop...with the HRRR suggesting near central ME and portions
of the interior to SE NH.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Generally quiet weather for Wednesday with seasonable
temperatures from the mid 30s over the higher terrain, to 40s
and some low 50s south. Wednesday night lows will drop into the
low to mid 20s for the higher terrain, and into the mid and
upper 20s elsewhere. Attention turns to a strong arctic cold
front and associated low tracking east across Quebec and the
Great Lakes. The feature will retrograde back towards the Hudson
Bay, so precipitation will not be noteworthy locally. There
will be an uptick in precip that develops along the front as it
crosses the area late Wednesday night into Thursday. The precip
will be primarily snow especially as temps drop behind the
front. No accumulations expected. The main impact from this
front will be an uptick in winds as cold air advection supports
deep mixing with gusts 30 mph or greater, higher in the
mountains.
Temps will rebound on Friday as we see returned flow. Meanwhile, a
larger storm system will move out of the Rockies ahead of a mid-
level low and trough. The surface feature will become better
organized as it moves east on Friday with moisture streaming into
the area Friday night. Snow and rain showers will increase with the
fropa, and as the sfc low approaches the area the showers will
continue to fill in. Steadier rain will transition to showers
Saturday afternoon, and then taper off on Saturday night as snow.
The track of the system will influence the wind magnitude and temp
advection, with the region firmly in the warm sector limiting the
snowfall potential. Should have a better idea on magnitude as we
approach the end of the week. Cold front will trail behind the
system with dry conditions Sunday.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Short Term...VFR conditions this afternoon will lower to IFR
across southern NH late this evening and overnight. SN/RA mix
will move across the region tonight, with a few showers
remaining Tuesday morning. AUG/RKD may escape some of the lower
restrictions as vis and cig impacts remain to terminals south.
Tuesday will see MVFR conditions remain during the morning, and
trend VFR in the afternoon. N to NW wind will carry a few more
gusts than Monday. VFR also expected Tuesday night.
Long Term...Non-VFR possible with a cold front Wednesday
night/Thursday.
&&
.MARINE...
Short Term...Below SCA criteria conditions as low pressure
passes well south of the waters this evening and overnight. Will
see rain/snow move across the area, with some visibility
restrictions possible. Waves remain mainly 1-2 feet.
Long Term...Conditions will be favorable on Wednesday but the
passage of a strong cold front early Thursday will introduce small
craft conditions to the waters, with gusts to gale force possible.
Some improvement by weeks end as the gradient relaxes Friday
allowing winds to subside. However, another storm system expected to
impact the coastal waters this weekend, though there remains much
uncertainty on the track and subsequent wind magnitude.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
UPDATE...Casey
NEAR/SHORT TERM...Cornwell
LONG TERM...Jamison
...UPDATED AVIATION FORECAST DISCUSSION...
.SYNOPSIS...
Issued at 357 PM CDT Mon Mar 27 2023
Key Messages:
- Several inches of snow expected this afternoon and evening
across southwest Nebraska into the western Sandhills.
- Winter Storm Warnings and Winter Weather Advisories are in
effect through this evening portions of the western Sandhills
and southwest.
- The potential for another system with accumulating snow mainly
across north central Nebraska Thursday night through Friday.
Convectively enhanced snowfall continues to develop across
portions of far southeast Cherry, Garden, Grant, Arthur, McPherson
into Keith County. This area from the latest HRRR and RAP
mesoscale models indicates 200-400 J/KG of elevated instability
exists in this area. A more widespread light to moderate snow
along and south of Interstate 80.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 357 PM CDT Mon Mar 27 2023
As an upper level trof currently located over southwest Nebraska
into far northwest Kansas with a surface low in the Texas
panhandle. Synoptic forcing with this system will be fairly strong
with an area of strong frontogenesis along the western side of
the H7 low late this afternoon and evening. The latest RAP model
shows elevated instability from 200-400 J/KG focused across
portions of Garden, Arthur, and Keith County. This convectively
driven/enhanced area of snow will be aligned along the
deformation axis. Given steep lapse rates and instability some
thundersnow certainly seems possible, particularly within the
deformation zone from southwest Nebraska up through the western
Sandhills.
Snow accumulations were increased in line with an HRRR and RAP
blend through this evening. With these model showing some
consistency, snowfall amounts from 5 to 10 inches are forecast
over eastern Garden, Arthur into Keith County. These counties are
now upgraded to a Winter Storm Warning. Heavy snow with
visibilities of a quarter mile or less can be expected, with
snowfall rates up to 2 inches per hour. Across the counties under
the Winter Weather Advisory, 3 to 5 inches of snowfall are
expected. locally higher amounts are possible. A tight gradient
in accumulations on the eastward side from Mullen through North
Platte and Brady, where less than an inch is expected and none
further east.
Snow diminishes after 03Z with northerly winds into this evening
mainly from 5 to 15 mph, so blowing and drifting will be minor.
Some clearing after midnight tonight, with lows from 15 to 20.
Expect quiet weather tomorrow with a return of afternoon sunshine.
Temperatures will be warmer but still below normal as highs range
from the lower 40s across southwest Nebraska to around 50 further
to the northeast. Winds will be westerly at 10 to 20 mph.
.LONG TERM...(Wednesday through Monday)
Issued at 357 PM CDT Mon Mar 27 2023
Medium range models including the GFS and ECMWF depict a
progressive pattern with some upper ridging building over the
region Wednesday night into Thursday. This will keep the region
dry, yet cool in the 30s on Wednesday behind a cold front and dry
and much warmer on Thursday with highs upper 50s to upper 60s.
A change by Thursday night as a deep upper trof moves through the
Rockies and Four Corners Region drives a strong cold front
through western Nebraska. This will drop temperatures significantly
and combine with increasing chances for precipitation to bring
snow back to Nebraska Thursday night into Friday. Ensemble QPF
plumes continue to show considerable spread so there remains a
good degree of uncertainty with this system late next week, but
probabilistic guidance currently indicates the most likely locations
to see impactful snow accumulations will be mainly north of
highway 2. Expect this forecast to change in the days ahead as new
guidance becomes available. Behind this system upper ridging
brings warmer and generally dry conditions to the area for next
weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 623 PM CDT Mon Mar 27 2023
Snow along with areas of MVFR/IFR will continue across the
western Sandhills into southwest Nebraska through tonight
(impacting KIML, KOGA, and KLBF terminals). Snow will gradually
taper off around midnight brining a return to VFR conditions
through the end of the TAF period. Winds will remain light
overnight at generally 5kts or less. These winds will shift
towards the west/southwest in the morning before increasing for a
brief period in the afternoon with gusts up to 20kt possible.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until midnight MDT tonight for NEZ022-035-
057.
Winter Weather Advisory until 1 AM CDT /midnight MDT/ Tuesday
for NEZ023-024-036-056-058-059-069>071-094.
&&
$$
SYNOPSIS...Roberg
SHORT TERM...Roberg
LONG TERM...Roberg
AVIATION...Viken
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1014 PM EDT Mon Mar 27 2023
.SYNOPSIS...
A cold front moves through tonight. Low pressure will pass well
offshore Tuesday night, with an upper shortwave bringing
showers. High pressure then builds in from the north and west
Wednesday and Thursday, before sliding offshore Friday. The next
frontal system will impact the area over the weekend.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of 1010 PM Mon...Frontal boundary has gotten a bit hung up
across the Piedmont of NC but has steady advanced southward
across VA, driving a small complex of showers and storms around
the Williamsburg area. The HRRR shows this complex gradually
easing southeastward towards OBX, but this same model has been
too aggressive with convective coverage most of the day. Could
see some light decaying showers move over the area and
maintained PoPs for that scenario. Otherwise, rest of the
forecast is on track.
Prev disc...A deepening area of low pressure will push off the
Delmarva Peninsula later this afternoon with the trailing cold
front pushing across the area this evening. Despite some
instability and available shear in place, very scant moisture
and weak lapse rates will prohibit vigorous TS development.
Can`t rule out an iso shower or storm early this evening, and if
one does form, it will be mainly along/N of Hwy 64. Temps
remain mild tonight with only weak CAA behind the front, with
lows generally in the 50s expected.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
As of 303 PM Mon...Quiet conditions expected with transitory
high in place before next system moves in. Highs will be
seasonably mild, generally around 70 S and W with upper 50s OBX.
Skies partly cloudy with light E to NE flow.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
As of 245 AM Mon...Unsettled weather Tuesday and Tuesday night
will be followed by a pleasant string of days mid to late week.
The next frontal system will impact the area next weekend,
though the precip characteristics of this front remain
uncertain.
Tuesday night and Wednesday... Low amplitude H5 trough moves
over the eastern US, with an embedded shortwave near the base of
the trough crossing the area Tuesday night into Wednesday.
Falling heights aloft will prompt the development of a wave
within the front well offshore, with increasing NE flow bringing
in a cooler maritime airmass. While overall moisture will be
limited, upper dynamics should be sufficient to squeeze at least
scattered showers out of the airmass Tuesday night into
Wednesday morning. Overall QPF will be low, only a few tenths of
an inch at most, but there is an increasing signal that much of
the area will see at least a little rainfall before sunrise
Wednesday.
Skies gradually clear midday through the afternoon Wednesday,
but persistent CAA will keep temps well below normal.
Wednesday night through Friday...General H5 height rises begin
later Wednesday and continue through the second half of the
workweek, with the upper ridging reaching its strongest later
Friday. At the surface, high pressure builds overhead Wednesday
night into Thursday, then is reinforced by stronger high
pressure building in from the Great Lakes region Thursday night.
This high moves offshore Friday, with surface return flow/WAA
developing in through the day. Dry conditions and ample sunshine
prevails through these several days, with temps trending back to
normal Thursday, then well above normal for Friday.
Saturday through early next week...Height falls ensue once
again next weekend as upper troughing moves over the eastern US.
Associated strong surface low lifts across the Great Lakes next
weekend, with the associated warm front possibly lifting
through ENC Friday night/Sat AM, anchoring our area within the
warm sector until cold frontal passage Sunday AM.
Pre-frontal flow Saturday/Saturday night currently looks to
have a strong westerly component, which is often an indicator of
a moisture starved front (a characteristic that the global
models can be slow to latch on to), and have limited POPs to low
end chance accordingly. Still, this period will require
monitoring for convective potential given the well above normal
temps and a lifting mechanism (cold front).
High pressure builds in from the south and west in the wake of
the cold front later Sunday into early next week, with
moderating temps and mainly dry conditions.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
SHORT TERM /through 00Z Wed/...
As of 730 PM Mon...High confidence in VFR conditions through the
period. Weak front, currently over the Piedmont, is expected to
begin crossing the region from the northwest after 04z. Some
guidance is quite aggressive with shower and tstorm development
along the boundary tonight, but lack of appreciable deep
moisture pokes a hole in this idea and maintained a dry
forecast. Behind the front, light N to NE winds are expected,
then veering easterly at the end of the period.
LONG TERM /Tuesday through Saturday/...
As of 3 AM Mon...Tuesday night brings the next chance of sub
VFR flight cats as at least scattered showers cross the area
under a passing shortwave. Later Wednesday through Friday brings
high pressure building in with relatively light winds and VFR
conditions. A frontal system this weekend could bring gusty
winds and shower/storm chances beginning later Friday through
Saturday.
&&
.MARINE...
SHORT TERM /through Tue/...
As of 303 PM Mon...Swrly gradient inc a bit late this afternoon
and marginal SCA cont for ctrl/srn waters S of Oregon Inlet.
Seas may build to 6 ft esp Ocracoke to Oregon Inlet leg. A cold
front will push across the waters overnight with a nly surge
keeping SCA winds in place for ctrl portions of the waters.
LONG TERM /Tuesday night through Saturday/...
As of 2 PM Mon...Low pressure developing offshore and high
pressure inland will bring breezy to strong N to NE winds
Tuesday night into Wednesday, with SCAs likely needed. Latest
guidance has trended a bit stronger with the NNE surge Wed
morning (HRRR and NAM in particular). There is potential for a
few hours of gale force winds, mainly south of Hatteras, between
8-12z. Will go ahead with SCAs for the Pamlico Sound and Neuse
River...which will need to be expanded to the coastal waters,
and possibly the northern sounds, when current SCAs expire. High
pressure builds overhead later Wednesday through Friday
morning, with mainly light to moderate winds, and minimal marine
hazards expected. The next stronger frontal system will impact
the area late Friday through the weekend, with current guidance
suggesting a prolonged period of gusty SW winds later
Friday/Friday night through Saturday night, with solid SCA
conditions expected, and gale force winds possible.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...Small Craft Advisory from 2 AM to 4 PM EDT Wednesday for
AMZ135.
Small Craft Advisory from 2 AM to 2 PM EDT Wednesday for
AMZ137.
Small Craft Advisory until 6 AM EDT Tuesday for AMZ152-154.
&&
$$
SYNOPSIS...MHX
NEAR TERM...TL/MS
SHORT TERM...TL
LONG TERM...CQD/CB
AVIATION...CB/MS
MARINE...TL/CB
Area Forecast Discussion
National Weather Service Raleigh NC
735 PM EDT Mon Mar 27 2023
.SYNOPSIS...
A cold front will move southeast across the Carolinas tonight. A mid
and upper-level disturbance will cross the region late Tuesday and
Tuesday night.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 735 PM Monday...
Central NC continues to be under the influence of strong SW flow
aloft between a mid-level disturbance currently over the eastern
Great Lakes/northern Mid-Atlantic and a subtropical ridge over the
Caribbean. At the surface, a 1010 mb area of low pressure is
currently centered over western VA, which will continue to move east
and offshore the Delmarva coast this evening. As it does so, it will
drag a prefrontal trough and cold front through central NC the rest
of this afternoon and this evening. The cold front is currently
located just west of the Triad, where dew points quickly dropping
into the 40s are now being observed, and the warm front has pushed
north into central VA. Thus all of central NC is still in the warm
sector, and dew points in the lower-to-mid-60s are being observed.
Skies have become partly cloudy for most of our region outside of
the far SE, so temperatures have warmed into the mid-to-upper-70s.
This has allowed MLCAPE to increase to as high as 1000 J/kg over the
western Piedmont according to latest SPC mesoanalysis, and latest
RAP forecasts have it continuing to increase to 1000-1500 J/kg
across much of central NC from now through early evening. Steep low-
level lapse rates (7-9 C/km) are also being observed in the NW
Piedmont, but the best mid-level lapse rates are over southern and
eastern portions of central NC. Temperatures aloft are fairly warm
and there is considerable dry air aloft at and above 700 mb. In
addition, there is a lack of large-scale upper forcing for ascent.
Despite these limiting factors, a line of showers and isolated
storms has already begun to develop along the cold front and
prefrontal trough, and it is currently pushing SE over the Triad.
The line will push SE through the rest of central NC over the next
several hours. Effective bulk shear is quite impressive, as high as
70 kts over the NW Piedmont, so if any updrafts are able to get high
enough, some hail will be possible, which looks to be the main
threat. Given there is less instability in our far southeastern
counties where widespread cloud cover stayed around longer today,
and given the timing of the line not getting there until after dark,
the threat is lower there. The line will diminish and exit the
Coastal Plain after about 03z. Winds will shift to the NW and N
behind the cold frontal passage, and skies will clear, before more
high clouds move in overnight from the west ahead of the next mid-
level disturbance. Thus increased forecast low temperatures a bit,
in the upper-40s to mid-50s.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
As of 315 PM Monday...
Behind the cold fropa, cold/dry advection is expected to briefly
continue through the early morning hours as the front continues to
sag south over the Southeast before stalling in a west/east
orientation extending from the SC coast to just north of the central
Gulf coast states. A 120-150kt upper level jet streak over the OH
Valley extending into the lower MS Valley will sag slightly
southeast and strengthen as a shortwave over the Mid MS Valley
shifts ESE into the lower OH Valley by 00z. This will position the
southern Mid-Atlantic within the optimal location underneath the
right-entrance-region of the upper jet, strengthening mid-level
flow, and glancing DPVA to lead to excellent upper level support for
upward motion. As this upper forcing approaches the Mid-Atlantic and
the Southeast, a weak wave of low pressure is expected to develop
over the Gulf Coast along the remnant baroclinic boundary from the
fropa mentioned above. This area of low pressure should track
northeast into the Carolinas by 00z, coincident with the best upper
forcing. As the low approaches, 700mb WAA maximizes along with low-
level FGEN support at 925-850mb within the deformation zone to
blossom precipitation directly over central NC Tuesday evening.
Significant drying at 500mb will likely be punching into central NC
ahead of the shortwave, but deep saturation below this layer co-
located with ample multi-layer ascent should sustain precipitation
over central NC for roughly a 6-8 hour period until the shortwave
pushes through the area late Tuesday night and promotes deep layer
subsidence in its wake. A broad area of 1027mb high pressure will
shift into the OH Valley by early Wednesday morning promoting a
secondary, reinforcing fropa leading to 6-8mb surface pressure rises
into Wednesday morning. CAA should lead to a well mixed boundary
layer overnight and may promote wind gusts up to 25 mph over the
Sandhills and southern Coastal Plain between 2AM and 8AM.
Precipitation totals range from a tenth of an inch across the
southern tier to up to a third of an inch across the northern
Piedmont into the central/northern Coastal Plain were the best
overlap of deep layer forcing exists. A pencil thin layer of
orographic cirrus near the Triad extending up into VA should be
present early Tuesday morning with very thin cirrus elsewhere. Upper
level cloudiness within the moist upper level flow should thicken
and lower through the day, tempering temperatures a bit during the
afternoon with forecast highs peaking in the low/mid 60s (N) to low
70s (S). Lows will largely be driven by CAA behind the reinforcing
fropa and expected to bottom out in the 40s with upper 30s possible
in the coldest spots.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
As of 230 PM Monday...
Wed-Fri AM: Upper ridging will slowly build east from the Rockies on
Wednesday to across the Carolinas by Friday. While the upper ridge
builds in, surface high pressure will build east from the Mid-
Mississippi River Valley Wednesday to across the Carolinas Wednesday
night and offshore Thursday. Another surface high will build from
the northern Plains Wednesday to the Ohio Valley Thursday and off
the Mid-Atlantic Coast by early Friday. These features will maintain
dry weather across central NC through early Friday. Highs will
increase from 5 degrees below normal on Wednesday to around 10
degrees by normal on Friday as subsidence increases across the
region. Slightly below normal lows Wednesday will increase to just
above normal by Friday morning.
Fri PM-Sat PM: As the surface ridge moves offshore, a prefrontal
trough may approach the region Friday afternoon, increasing chances
for showers from NW to SE throughout the day and night. By Saturday,
a cold front will approach from the west, and an upper trough will
swing east from the TN Valley to NC by Saturday night. These
features will provide a better chance of precipitation compared to
Friday. Additionally, strong low-level and deep-level shear, along
with weak instability, could generate thunderstorms across the
region, with the best chances closer to the Coastal Plain where
surface dewpoints in the low 60s remain. Winds will increase through
the period, and especially Saturday as a lower-level jet moves into
the area and pressure gradients increase. SW wind gusts could be as
strong as 30-40 mph on Saturday, then begin to diminish Saturday
night behind the front. Widespread mid-70s to low 80s are expected
for highs, with lows around 60, which is around 20 degrees above
normal.
Sun-Mon: Surface high pressure then builds east from the Midwest
Saturday to the Mid-Atlantic Sunday and off the coast around Monday.
At the same time, weak upper ridging returns as it builds in from
the west and will help keep conditions dry to start the next week.
Cold air advection behind Saturday`s front will help lower highs to
the 60s and 70s Sunday, then increasing subsidence and warm air
advection Monday increase highs to the 70s area-wide.
&&
.AVIATION /00Z MONDAY THROUGH SATURDAY/...
As of 800 PM Monday...
Although there are still a few showers across the region, all sites
are currently VFR and expected to stay VFR through the night, unless
a stray shower passes over a terminal. The front is currently still
west of the NW Piedmont. As it moves through the region, expect a
wind change overnight from southwesterly to northerly by early
morning. Northerly winds will continue for most of the day Tuesday
with another round of sub-VFR conditions possible near the end of
the TAF period.
Outlook: The approach and passage of a mid/upper-level disturbance
will result in a chance of rain and sub-VFR restrictions Tue night.
After a period of dry weather from Wednesday through Friday, a cold
front will bring another chance of showers/storms and sub-VFR
restrictions on Saturday.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$ SYNOPSIS...CA/MWS
NEAR TERM...Green
SHORT TERM...Swiggett
LONG TERM...JJT
AVIATION...CA/MWS