Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/12/23
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1017 PM EST Wed Jan 11 2023
.SYNOPSIS...
Clouds will thicken and lower overnight ahead of a warm
front with some light snow developing south and west of the Capital
Region. A storm system will bring widespread precipitation to the
area Thursday into Friday. The precipitation will be mainly rain,
however some light snow, sleet and or freezing rain will occur
during the day mainly across the southern Adirondacks and southern
Greens. Rain will occur Thursday night into Friday, as the system
moves to our east Friday, colder air will move back in changing the
rain to snow as it tapers off. Some lingering snow showers will
continue into Friday night with fair weather returning Saturday.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
.UPDATE as of 945 pm EST...Clouds continue to thicken and lower
across eastern NY and western New England. A weak mid-level
short-wave and sfc trough is moving across eastern NY and
western New England depicted on the latest RAP, water vapor
imagery and sfc analysis with some light radar returns showing
up over the western Mohawk Valley/southern Adirondacks/Lake
George Region and Catskills. The low-levels remain dry with sfc
dewpoints mainly in the mid teens to lower 20s over eastern NY
in the NYS mesonet and the western New England observations this
hour. Some flurries or an isolated snow shower is possible. We
adjusted the PoPs slightly and some scattered dustings or an
isolated tenth of an inch is possible over higher terrain. The
NYS mesonet does not show any measurable pcpn as of yet in the
ALY forecast area, though a few of the web cams show a few
flurries over the southern Dacks.
Some clearing is noted over western NY, but the clouds should
hold in place overnight, as we kept it cloudy/mostly cloudy in
the wake of this lead disturbance. The warm front is still over
the Ohio Valley and the Mid Atlantic States. The boundary should
lift slowly northward in the early to mid morning hours
allowing the isentropic lift to increase towards daybreak for
some light snow to break out especially south of the Capital
Region. We did trim the timing and PoPs back slightly based on
the latest 3-km HRRR and NAMnest. The initial surge of moisture
is spotty based on the observations to the south over the mid
Atlantic States. Temps will only cool slightly with the clouds
and some minor wet bulbing towards daybreak, as lows will be
mainly in the 20s to around 30F in the mid Hudson Valley with a
few upper teens over the southern Adirondacks and the southern
Greens. We should have a south/southeast breeze increase towards
daybreak over the higher terrain and the confluent area of the
Capital District.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
Winter Weather Advisory has been issued for the southwest
Adirondacks including all of Herkimer County, and higher
elevations in southern Vermont from 7 am Thursday to 5 am Friday
for mixed precipitation including snow, sleet and freezing rain.
The region will be impacted by a low pressure system through
the period. Despite what the calendar says it will bring mainly
rain to the area.
A southern stream system will move out of the Southern Plains
and deepen over the Ohio Valley as northern stream energy comes
in play. The system`s surface low is expected to track across
northern New York keeping the area on the warm side of the
system. Initially as warm air advection precipitation overspreads
and develops over the area; it will be cold enough for light
snow. Warmer air will move in aloft and the boundary layer will
warm. A changeover to rain is expected as the day progresses,
however across the southern Adirondacks and southern Vermont
snow will linger longer and a period of freezing rain and sleet
is expected as surface temperatures take longer to warm and we
have warmer air aloft. Looking at light snow accumulations of up
to two inches and ice accumulations of up to around one tenth
of an inch. This prompted the issuance of the Winter Weather
Advisory.
Far from typical for January, rain will occur through Thursday
night into Friday morning. It will be unpleasant with
temperatures only in the mid 30s to lower 40s. The QPF will be
heaviest Thursday night as the system`s warm front approaches
and lifts through. The QPF amounts will be lighter across the
Schoharie Valley and the Capital District due to downsloping.
The surface low will move across the area Friday morning with
colder air be ushering back in its wake with rain mixing with
changing to snow across the higher terrain as the precipitation
tapers off Friday.
Southeast flow ahead of the warm front will brisk in brisk and
gusty southeast winds across the higher terrain east of the
Hudson River and across the Adirondacks and Caskills. The
strongest winds associated with the system will remain to the
southeast of the local area.
Temperature will rise is the warm sector Friday to the south
and east of the Capital District. Expecting rather steady
temperatures in the mid/uper 30s across the southern Adirondacks
with temperatures rising in the 40s to lower 50s across the rest
of the area. Temperatures will drop back into the teens and 20s
Friday night in cold air advection with some lingering snow
showers in the cyclonic flow on the backside the system.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Departing system could allow for some lingering clouds, and perhaps
spotty snow showers/flurries Saturday morning, especially north of I-
90. It will be somewhat breezy with west/northwest winds possibly
gusting 20-25 mph, particularly within the Mohawk Valley/Capital
Region and Berkshires. Seasonably chilly temperatures in the 20s to
lower/mid 30s are expected.
High pressure looks to bring fair weather for Saturday night through
Monday. Overnight lows will be cold, especially across the southern
Adirondacks where single digits or slightly colder mins are possible
Sat nt. Highs mainly in the 20s and 30s Sunday, and 30s to lower 40s
Monday.
Weakening system approaches for Tuesday, possibly bringing spotty
light precipitation to the region. Depending on start time, there
could be some light snow or a wintry mix, especially north of I-90,
otherwise mainly rain. Generally fair weather and above normal
temperatures return for Wednesday, although clouds will likely
persist, and a few showers of rain/snow could occur across the
southern Adirondacks.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Lowering Cigs overnight, with Cigs initially 4000-5000 FT AGL,
lowering to MVFR from south to north between 08Z-12Z/Thu.
An approaching warm front will bring some light snow to the TAF
sites Thursday morning, beginning between roughly 12Z-15Z/Thu. A
period of MVFR/IFR Vsbys is likely once the snow begins. Light
snow should then transition to a mix of sleet/rain, before
changing to rain/drizzle by 18Z-20Z/Thu. There is a slight
chance that some freezing rain could occur during this
transition at KGFL, which could linger as late as 22Z/Thu.
Mainly MVFR Vsbys, and MVFR/IFR Cigs are expected Thursday
afternoon.
Light/variable winds overnight will become east to southeast by
late Thursday morning into the afternoon, and increase to 5-10
KT, with perhaps a few gusts up to 15-20 KT in the afternoon at
KPSF.
Low level wind shear will be possible by late Thursday
afternoon, as winds around 2000 FT AGL increase from the
south-southeast to 30-40 KT, while surface winds remain
generally less than 10 KT from the east/southeast.
Outlook...
Thursday Night: High Operational Impact. Definite RA.
Friday: Moderate Operational Impact. Breezy. Likely SHRA...RA.
Friday Night: Low Operational Impact. Chance of SHRA...SHSN...SN.
Saturday: Low Operational Impact. Slight Chance of SHSN.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
Martin Luther King Jr Day: No Operational Impact. NO SIG WX.
&&
.HYDROLOGY...
Rises along area streams and rivers expected Thursday night and
Friday in response to runoff from expected rainfall, however no
flooding is expected at this time. There is essentially no snow
pack to melt south of the Adirondacks and higher elevations of
the Green Mountains, so snow melt will not be a hydrologic
factor except for our far northern counties. Ponding of water on
roadways may occur where heavier rainfall occurs.
For details on specific area rivers and lakes, including observed
and forecast river stages and lake elevations, please visit the
Advanced Hydrologic Prediction Service /AHPS/ graphs on our
website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Winter Weather Advisory from 7 AM Thursday to 5 AM EST Friday
for NYZ032-033-038-042-082.
MA...None.
VT...Winter Weather Advisory from 7 AM Thursday to 5 AM EST Friday
for VTZ013-014.
&&
$$
SYNOPSIS...IAA/Wasula
NEAR TERM...Wasula
SHORT TERM...IAA
LONG TERM...KL
AVIATION...KL
HYDROLOGY...IAA
Area Forecast Discussion
National Weather Service La Crosse WI
500 PM CST Wed Jan 11 2023
.DISCUSSION...(This evening through Wednesday)
Issued at 220 PM CST Wed Jan 11 2023
Key Messages:
- Seasonal temperatures for the rest of the week with highs in
the 20s and 30s--warmer weather for the weekend.
- Flurries may occur tonight in southeast Minnesota and again
Thursday east of the Mississippi River.
- Next chance of impactful weather still on the docket for Monday
and Wednesday of next week.
Tonight into Thursday: Scattered Flurries
An elongated upper trough is sinking southeastward over north-
central North Dakota this afternoon with increasing northwesterly
surface flow taking place as a broad low pressure pushes along the
WI/IL border. A few flurries are possible with its passage,
mainly west of the Mississippi River as hinted at by the HRRR
along a low-level frontal surface. A second wave rotating
southeastward behind its counterpart during the day on Thursday
interacts with the frontal zone--now over central Wisconsin--and
may fuel another round of light flurries/snow showers. Impacts are
expected to be minimal, though the CAMs are more robust with
their simulated reflectivity fields. Thus, cannot rule out a
light dusting of snow in a few locales.
Friday into Sunday: Warming for the Weekend
The upper tropospheric pattern amplifies for the end of the week
with ridging over the West Coast shifting eastward through the
central CONUS Friday into Saturday. Low to mid-level tropospheric
warm air advection ensues Friday night on the backside of a
departing surface ridge and continues through the day on Sunday.
Highs for Saturday and Sunday should warm 5-8 degrees over the
previous days, with readings in the upper 30s to low 40s for
Sunday. Dry conditions are expected during this time under the
ridge.
Monday and Wednesday: Next Round(s) of Wintry Precipitation
Longwave troughing carves out the western CONUS for much of next
week with several fast-moving shortwaves propagating through the
flow at various points during the week. The overall synoptic
pattern is well-resolved by the global models, with the devil in
the details on the timing/placement of the embedded southern
stream shortwaves. The first wave ejects into the High Plains on
Monday with increasing isentropic ascent and theta-e advection
ahead of the low fueling widespread precipitation through the Mid-
Mississippi River valley. The forecast area sits on the northern
side of this precipitation shield where precipitation type will
come into play, though about 20-30 percent of the ensembles are
trending southward with the placement of the precipitation and
keeping parts of the area dry. After a brief lull in the activity
on Tuesday, the second wave digs into the Four Corners and lifts
northeastward, once again bringing widespread wintry precipitation
to the central U.S.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 500 PM CST Wed Jan 11 2023
CIGS; sub 1 kft cigs return as low stratus flows back across the TAF
sites. Expecting some minor improvement for Thu afternoon, but cig
restrictions aren`t likely to give way until later in the day Friday
as high pressure pushes in from the west.
VSBY: fog will drop vsbys sub 1sm at KRST this evening, mostly MVFR
for KLSE. Expect some improvement overnight as drier air presses in
from the northwest and winds kick up a bit.
WINDS: northwest winds will be on the increase overnight, staying
brisk for much of Thu with tightening sfc pressure gradient. Could
see a few gusts around 20 kts at KRST on Thu, although mixing is
relatively shallow and not much above the expected sustained speeds.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...Skow
AVIATION.....Rieck
Area Forecast Discussion
National Weather Service Billings MT
515 PM MST Wed Jan 11 2023
.UPDATE...
Miles City and Baker airports continue to report visibility of a
half mile or less, and web cameras show very poor visibility from
Baker to Ekalaka. Have updated weather grids to raise fog coverage
to "areas" rather than "patchy" right now near the Dakotas
border, and also brought mention of fog later tonight as far west
as Treasure and western Powder River counties (per recent HRRR
runs). Obviously, the dense fog advisory is in good shape and will
make no changes.
Next few days will be quite mild, especially Friday & Saturday
when many places will see 50F or warmer. Air mass itself will be
warmest Friday (700mb temps near +3C) but Saturday temps will be
aided by increased mixing behind an early morning shortwave. Have
tweaked some temps up Thursday-Saturday based on latest guidance
and ensembles...as well as recent NBM performance.
JKL
&&
.DISCUSSION...
Through Friday Night...
Satellite imagery this afternoon an upper trough moving across
Colorado into the plains while an upper ridge axis prevailed over
the northern Rockies. Low clouds and fog was indicated across the
Dakotas and into portions of northern and eastern Montana.
Fog conditions have improved a bit over east central Montana, but
pockets of low clouds and fog still lingered thanks to the cold
air advection of this mornings backdoor cold front. High-
resolution models suggest another night of dense fog possible from
Forsyth to Miles City and east to Baker and Ekalaka. Some of this
might even develop into Treasure and northeastern Yellowstone by
Thursday morning. We have extended the Dense Fog Advisories for
Northern Rosebud, Custer and Fallon tonight through noon Thursday.
Slick roads, sidewalks and especially bridges are possible as
temps will be well below freezing.
The other forecast issue is gap winds at Livingston. As high
pressure sets up over SE Idaho, a pressure gradient looks to form
over south-central MT in a favorable position for gap winds at
Livingston and Nye. Latest local guidance shows winds increasing
tonight, and peaking Thursday night, with a 57% chance for gusts
to exceed 50 mph, and a 28% chance to exceed 58 mph. We will
forego any wind highlights for now, but message the potential for
crosswinds on I-90 near Livingston. The winds are expected to
slowly back off Friday, but remain brisk.
Otherwise, strong high pressure aloft will prevail over the
Rockies and adjacent high plains through Friday. A few snow
showers may linger tonight over the Absarokas/Beartooths, but
otherwise dry conditions are expected with afternoon highs
above normal.
Lows tonight will range from mid 20s west to teens east. Expect
slightly warmer temperatures Thursday with highs in the mid 40s
west to mid 30s east. Highs by Friday will be near 50 west to
lower 40s east. BT
Saturday through Wednesday...
This period looks unseasonably warm and dry. Ridging continues
Saturday with widespread highs in the 50s Saturday and Sunday. Cluster
analysis is in good agreement in the ridge breaking down through
the afternoon Sunday into Monday. This is expected to bring
cooler temperatures in the mid 40s Monday before temps hover near
40 the rest of the forecast period. Main impacts at this point
looks to be southwest mountain snowfall near the end of the
forecast period with near 40% chance for four inches in some
areas. Torgerson
&&
.AVIATION...
Areas of dense fog and low clouds will continue from over far NE
Rosebud County to KMLS to KBHK S through Carter County through 18Z
Thursday. Conditions will be LIFR to VLIFR. Further W...there will
be patchy fog and low clouds W of the dense fog areas, affecting
far eastern Musselshell, far NE Yellowstone, Treasure, the
remainder of N. Rosebud and Powder River Counties. Some of the
patchy fog will be dense. Otherwise, VFR conditions will prevail.
Arthur
&&
.PRELIMINARY POINT TEMP/POPS...
Thu Fri Sat Sun Mon Tue Wed
-----------------------------------------------------------
BIL 026/046 033/052 036/053 029/045 028/041 026/042 025/042
00/U 00/B 01/B 11/B 21/B 11/B 11/B
LVM 025/046 034/055 036/050 029/043 025/041 023/038 022/039
00/N 00/N 11/N 12/S 32/S 11/B 12/S
HDN 016/041 022/050 025/050 024/043 023/038 021/038 018/041
00/B 00/B 01/B 11/B 21/B 11/B 11/B
MLS 017/034 020/043 024/044 024/039 023/033 021/033 019/035
00/F 00/B 01/E 01/B 11/E 11/E 00/B
4BQ 019/041 024/049 028/049 027/045 026/039 024/038 022/040
00/B 00/B 00/B 01/B 12/S 11/B 11/B
BHK 015/034 019/042 025/042 023/037 020/033 018/030 015/032
00/F 00/B 00/B 01/B 11/B 11/E 10/B
SHR 017/043 024/052 029/050 024/042 022/038 020/037 017/039
00/U 00/B 01/B 01/B 22/S 11/B 11/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Dense Fog Advisory in effect until noon MST Thursday FOR
ZONES 31>33-37.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Dodge City KS
851 PM CST Wed Jan 11 2023
...updated for current trends...
.UPDATE...
Issued at 849 PM CST Wed Jan 11 2023
Minor update to cover radar trends and spatial – temporal extent
of wintry precipitation/snow accums. Mesoscale analysis has 850
mb low just east of the DDC area moving into central Kansas.
Surface temperatures seem to be falling either right with HREF
probability of freezing trends or even faster. Not really much of
a frontogenesis field, but 850 mb temp advection differential is
likely the reason a small are of enhanced snowfall was occurring
north to Garden into Lane county. Adjusted QPF to the HRRR values
and the FB is giving us up to an inch in that narrow, sub- county
corridor. Highway 4 east of Scott State lake was already snow
covered last hour. No other real changes to mention.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 1212 PM CST Wed Jan 11 2023
18Z observations are showing a 5480 dm 500 mb low located just
southwest of Goodland and a 1004 surface low located north of
Lamar, Colorado. Skies have cleared in the vicinity of the low
pressure centers with high and mid level clouds continuing to move
to the east for areas along and east of highway 283. Post frontal
and backside low snow and rain has developed in the front range of
the Rockies and this will be the areas of focus for our rain/snow
chances tonight.
For tonight the general trend in short term observations and model
output is that the surface and upper level low should move in a
more southeast direction which would take the upper level dynamics
more across our forecast area. Despite the better lift this system
is moisture starved as it has crossed the mountains with little
surface moisture available from the gulf. As a result a post
frontal mesoscale band of rain/snow will move from northwest to
southeast across the CWA tonight with the potential of 0.5 inch of
snow roughly along our I-70 counties where the coldest air and
best chance of higher QPF still exists. Elsewhere as you move
further south the chances of QPF fall quite a bit to where we may
only see a few hundredths for areas south of highway 50. Winds
will also sharply increase as the low departs later tonight to
where we could see widespread winds sustained to 30 mph and gust
potential to over 50 mph for a few hours between midnight and
sunrise. Lows should fall back into the 20s.
Thursday as the low departs and a high pressure center moves in
the winds should diminish during the day and clouds will clear.
Overall we should be left with a typical January day as highs get
into the 40s.
Thursday night with high pressure in the central plains it should
be light winds and clear skies with lows in the upper 10s to lower
20s.
.LONG TERM...(Friday through Wednesday)
Issued at 141 PM CST Wed Jan 11 2023
Generally quiet conditions for the long term. We will start with
an upper level ridge moving into the central and northern plains
for Friday and Saturday and this should allow winds to turn back
to the south to southwest and help to warm us into the 50s and
60s.
On Sunday deterministic and ensemble models are all showing a fast
moving trough moving into the southern plains which will intensify
a surface low in southeast Colorado. This will increase the
surface winds out of the southwest and help to warm us into the
lower 60s. Most models are showing the bulk of the precipitation
staying to the east of the CWA as the upper level forcing looks to
be stronger as the cold front passes Sunday night. Overall will
keep some slight POPs for areas mainly along the I-70 corridor.
Early next week we start off with an upper level ridge and then
another storm system looks to be on the horizon for next
Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 450 PM CST Wed Jan 11 2023
A low pressure center will move across the area in the first 6
hours of this TAF window. The result will be diminishing winds in
the southwest region with time (LBL area) as a diurnal transition
from very strong gusts above 40 knots weakens but remains
moderately windy through the evening. Farther north, a
deterioration of the ceilings, mainly into an MVFR category,
through mid evening coupled with a limited IFR visibility impact
in about a 4 to 5 hour window of scattered precipitation of -RASN.
Following that, weakening northwest surface winds and diminishing
clouds are expected heading into the day Thursday.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 26 48 21 48 / 30 0 0 0
GCK 24 47 19 51 / 30 0 0 0
EHA 25 51 24 58 / 20 0 0 0
LBL 25 50 21 55 / 0 0 0 0
HYS 24 43 19 43 / 60 0 0 0
P28 29 47 22 45 / 10 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Russell
SHORT TERM...Tatro
LONG TERM...Tatro
AVIATION...Russell
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
911 PM CST Wed Jan 11 2023
...Short Term Update...
.UPDATE...
Issued at 911 PM CST Wed Jan 11 2023
Regarding very short term weather trends through sunrise Thursday
(next 6-10 hours):
1) Far southern CWA snow potential (north central KS):
- It took a while, but within the last hour or so we have finally
seen automated airport obs and a ground-truth report from Rooks
County KS dispatch confirming that some wet, slushy snow
accumulation has gotten underway in our extreme south-southwest
coverage area (CWA). Light precip is also evident within mainly
Osborne/Mitchell counties, but this could still be light rain
(yet to change over).
- Going forward, while overall situation discussed by day shifter
below remains very valid with regard to snow accumulation
potential in our far southern KS zones (mainly 0.5" or less),
very latest HRRR suggests that perhaps especially southern Rooks
County could end up closer to 1" before the main snow band
finally departs south of the area by around midnight. So a non-
zero chance for some minor/nuisance travel issues as some slushy
snow accumulates on roads (and possibly "overachieves" our
official forecast a bit), but with overall accumulation still
looking like 1" or less within the vast majority of that area,
still cannot justify a formal Winter Weather Advisory...especially
with only a few hours of accumulation potential left before
precip vacates entirely. Have at least boosted snow chances
(PoPs) to 70-80 percentages this evening to acknowledge the
reality that precip is actually occurring.
2) Far northern CWA fog potential:
- Although not expecting it be a "big deal", have introduced some
"patchy fog" to the forecast for overnight for mainly a handful
of far northern counties (mainly
Valley/Greeley/Nance/Sherman/Howard), as upstream obs over
northern NE along with higher-res visibility guidance from HRRR
suggest that at least light fog will advect southward into the
area, likely driven in part by enhanced low-level moisture from
lingering snow cover. Thanks to steady north winds of 10-20 MPH,
truly dense fog should really NOT be an issue, but felt at least
a generic "patchy fog" forecast inclusion was warranted. For
now, only have this in the official forecast through 6 AM, and
will defer to overnight shift to see if it may need extended
beyond that.
&&
.DISCUSSION...(This evening through Wednesday)
Issued at 335 PM CST Wed Jan 11 2023
Key Messages:
* Brief bout of rain changing to wet snow this evening/overnight.
Little to no snow accumulations.
* Dry and cooler Thursday before nice warming trend develops
Friday and continues into the weekend.
* Pattern trends cooler and at least somewhat more active early
next week
Forecast Details:
Relatively quiet day, thus far, but both clds and winds are on the
incr as low pressure deepens over the central High Plains
underneath a rather potent upper level trough. Latest satellite
data depicts a distinct and organized area of vorticity currently
crossing the state line from E CO into W KS and models are in good
agreement in shifting it E along KS/OK border as a semi-closed
upper low. This is a little further S compared to 24hrs ago, esp.
w/r/t the H7 low. Yesterday`s early runs of the HRRR/RAP were
fairly aggressive with QPF and snow amnts (for at least S half of
CWA) this eve/night w/ an H7 low tracking from roughly GLD to ICT
while remaining mostly closed. Now that the low has crossed the
Rockies and satellite data shows a very potent/distinct vort max
near Lamar, CO with clear momentum to the SE lends credibility to
model trends of now keeping majority of QPF just S of CWA. May
still have a 3-6hr window for pcpn to reach the ground after
sunset and before 09Z, but some of this may initially be rain or
rain/snow mix. Thus, not expecting much, if anything, for snow
accums besides perhaps areas S of Cambridge, NE to Beloit, KS. for
a dusting to half inch. Otherwise, more sensible wx issue for most
will be chilly, brzy N winds and arrival of low stratus.
System quickly departs to the SE by dawn Thu, but low clds and
chilly N winds will continue into the daytime hrs, at least for
the AM hrs. This will lead to wind chills in the single digits and
teens for Neb zones, with highs only in the upper 20s to 30s. Kan
zones may get a bit warmer with some clearing, upper 30s-low 40s.
Models are in good agreement showing a nice warming trend Fri into
the weekend as upper heights build over the Rockies then shift E
onto the Plains. Upper flow turns SWrly and sfc troughing deepens
over lee of the Rockies by Sun, which should lead to warmest day
in the upper 40s to upper 50s. Winds will be a bit brzy out of the
S on Sat, but should be much lighter for Sun. Overall, not a bad
weekend by January standards.
Upper pattern transitions to somewhat more active and cooler
pattern as we head into next week. GFS and EC are in good
agreement bringing a weak/progressive shortwave across the area
Sun night into Mon, and possibly a stronger/deeper wave towards
Wed/Day 7. The Sun night system looks to have a potentially
favorable track for snow in our CWA (sfc low moving from SW KS
into central IA). However, with lack of cold air to work with and
progressive nature of wave, neither snow or QPF in general look
very impressive attm with 12Z EPS probs for at least 0.1" of QPF
only 10-20 percent. The midweek system could be stronger and have
more moisture to work with, as evident by at least 40-60 percent
probs for at least 0.1" of QPF. Temps will cool off mid to late
next week, but probably only back to near-normal levels.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday)
Issued at 450 PM CST Wed Jan 11 2023
An IFR ceiling is forecast to form over the TAF sites this
evening behind a cold front. Behind the front expect northerly
winds to gust into the mid 20s until tomorrow afternoon. Wouldn`t
be surprised at some flurries this evening, otherwise will keep
the forecast dry as not expecting to many impacts to the TAF
sites.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...Pfannkuch
DISCUSSION...Thies
AVIATION...Beda
Area Forecast Discussion
National Weather Service Grand Rapids MI
1018 PM EST Wed Jan 11 2023
LATEST UPDATE...
Update
.UPDATE...
Issued at 1013 PM EST Wed Jan 11 2023
Low pressure is pushing a cold front across the cwa at this time.
A few showers have developed over the northeast cwa and we updated
the pops to reflect this. Generally a cloudy night expected.
Latest HRRR shows the precipitation moving southeast of the CWA
Thursday. We`ll wait for other guidance to come in before
modifying PoPs for Thursday.
&&
.DISCUSSION...(This evening through next Wednesday)
Issued at 245 PM EST Wed Jan 11 2023
- Lowering chances for precipitation Thu into Thu night
The models have been trending toward less of a potential for
precipitation with the next storm system. Most models track the
system through southeastern OH. This more southern track allows
for drier air to filter into the system from the north from about
850 mb to 700 mb. The deeper moisture is mainly confined to the
Jackson region in our CWA...which is where we will feature the
highest POPs. With the temperature above freezing for most of the
event...the potential for impacts is limited. One item to monitor
is after midnight Thursday night. This is when the surface
temperatures fall to below freezing and the DGZ is only marginally
saturated. Thus a small window of possible freezing precipitation
may exist...however confidence on this occurring was not high
enough to feature it in the forecast.
- Above normal temperatures Sunday into Wednesday
High pressure strengthens as it tracks eastward into the Central
Appalachians Sunday into Monday. Deep warm and moist air
advection occurs early next week. One low pressure systems is
shown to track up through the Western Great Lakes region on
Monday. This will put the CWA in the warm sector. So high/low
temperatures will trend to above normal values. Then a cold front
weakens as it tracks into the CWA Tuesday. Weak high pressure then
ridges in for Wednesday...which should allow for some sunshine.
With no arctic air around...we should still climb to above normal
temperature values for the middle of next week.
- Above normal precipitation next week
The Gulf opens up next week and the stream of moisture into the
Great Lakes region is well above normal for this time of the year. PWAT
values make a run toward an inch. A deep upper low south of AK
advances eastward through the period. Ahead of this low...several
southern stream waves track into the Great Lakes region...one on
Monday and a second Thursday. With multiple rounds of widespread
rain...we will likely end up with above normal qpf next week. This
does show up in the latest 6 to 10 day outlook from CPC.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 643 PM EST Wed Jan 11 2023
Latest nephanalysis shows MVFR cigs developing over far southwest
Lower with IFR/LIFR over northern Indiana associated with low
pressure crossing Lake MI. Short range progs show the IFR...with
potential LIFR cigs...moving north tonight over the terminals.
Didn`t include LIFR but can`t rule it out for a couple of hours
after midnight. Light rain is expected at JXN Thursday afternoon.
Conditions will improve late in the period.
East/southeast winds will become northerly after the cold front
associated with the low moves through.
&&
.MARINE...
Issued at 245 PM EST Wed Jan 11 2023
The winds and waves will increase from the north Thursday as the
low pressure system pulls off to the east. It looks like we mostly
mix into the 20 to 30 knot winds over the nearshore zones. Cold
air advection will also support building waves. There is still a
risk for a low end gale event...mainly over the southern zones.
The hazardous conditions will likely linger through Friday given
the relatively tight pressure gradient that stays in place.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Gale Watch from Thursday afternoon through Friday morning for
LMZ844.
&&
$$
UPDATE...04
DISCUSSION...MJS
AVIATION...04
MARINE...MJS
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1010 PM EST Wed Jan 11 2023
.SYNOPSIS...
Surface high pressure will move offshore tonight. A strong cold
front will move through the area Thursday afternoon and evening,
bringing rain and thunderstorms. Cold high pressure will build in
behind the front on Friday and linger through the weekend with a
warming trend expected early next week. Another cold front will
likely bring more precipitation on Tuesday.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 1000 PM EST Wednesday: Main update needed this evening was the
decreasing of PoPs through Thursday morning based on the latest CAM
guidance. Otherwise, the fcst remains on track. Flat upper ridging
remains in place across the Southeast, with an upper low currently
centered over the OK/KS border and expected to rapidly dig across
the Great Plains overnight, deepening the associated surface low as
it does so. For the Carolinas, though, little change is expected
apart from thickening of the existing cirrus and strengthening of a
SW wind across the area. A diffuse warm front continues lifting
northward across the region...leaving us in a moist WAA regime for
the remainder of the near-term forecast period. Tonight, conditions
will begin to deteriorate as heights start falling and the Plains
trough drifts into the Ozarks. Model profiles become saturated at
the low levels after midnight, especially across the western half of
the forecast area...supporting light showers for the upslope-
enhanced mountain zones and perhaps even patchy drizzle for parts of
the Upstate. Fog looks to remain confined to the mountain valleys
again tonight, with too much cloud cover and too little BL moisture
elsewhere. Lows should be easily 15 degrees above climo, only
dropping into the upper 40s.
Little improvement is expected tomorrow as the atmosphere becomes
increasingly unsettled. A 250mb jet streak will dip into the
Carolinas through midday while heights continue to fall and
a band of strong DPVA works into the region by mid-afternoon.
Although widespread cloud cover is anticipated most of the day,
models are in good agreement that the mid-level moisture needed to
support rainfall will hold off until shortly before the arrival
of a convective band during the afternoon hours...precluding
much of a chance of any working over of the atmosphere ahead of
the system. Instead, most CAM guidance depicts some 500-1000
J/kg of sbCAPE values across the western Upstate by late afternoon
when the convective band arrives...with the ARW and FV3 depicting
markedly lower values than the NAMnest and RDPS, which fall on the
higher end of this range. In any case, HREF members are in good
agreement that as a potent 850mb LLJ crosses the Appalachians and
into the CWA after daybreak, effective shear values will skyrocket
to at least 45kts and potentially much higher. The new 12z HREF
has trended upward in depicting excellent SRH values supportive
of rotating updrafts (although instability is shallow enough
that this doesn`t really get captured by its updraft helicity
product)...and with shear vectors oriented at roughly a 45-degree
angle to the approaching boundary, both discrete convection as
well as QLCS-type storm mode are supported. A potential major
caveat to this is that NAMnest and RDPS soundings both depict
a weak capping inversion before the main line arrives...which
may suppress discrete convection ahead of the line. Indeed, the
HRRR and ARW depict some discrete cells, but not until after the
system has shifted too far east for those cells to impact our CWA.
Regardless...excellent low-level SRH will be enough for a passing
tornado threat, at least within the convective line before it
moves off to the east during the late evening hours.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 205 pm Wednesday: Convective band will be moving east of the
CWA at the start of the period, or shortly thereafter, with cold air
advection likely well underway across the mountains in the wake of
the front Thursday evening. As such, snow levels will be steadily
falling as the northwest flow machine begins to crank up, and 1-2
inches of snow appear to be a good bet across the high elevations
along the TN border by daybreak Friday. There is likely to be a bit
of a lull in snow shower coverage Fri morning, before everything
ramps up again Fri afternoon and evening as the main upper trough
sweeps across the area. This will be the most likely time frame for
accumulating snow showers, as moisture depth and very well
mixed/unstable boundary layer will be at their deepest and thermal
profiles will be most favorable (temps as cold as -13C at the top of
the moist layer). In fact, the NAM has consistently been depicting
weak sbCAPE in the upstream air mass across the TN Valley, while
backward model trajectories clearly indicate a Great Lakes
connection in the low level flow by Fri evening.
For the time being, this looks to be a solid Advisory-level event
for at least the higher elevations along the TN border, with total
amounts in the 2-6" range and locally higher amounts by the time the
event winds down early Saturday. Additionally, would expect a few
snow showers to break containment of the usual TN border areas when
instability and upper forcing are at their nadir Fri afternoon/
evening, producing spotty amounts ~1 inch or less across portions of
the central NC mountains. Otherwise, winds will be gusty across the
higher terrain in the cold advection regime, but the forecast
surface gradient and H8 wind magnitudes suggest minimal Wind
Advisory conditions at worst. Temperatures will otherwise be a few
degrees below climo through the period.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 210 PM Wednesday: The extended forecast picks up at 00z on
Sunday with broad and deep upper trofing moving off the Atlantic
Coast and upper ridging building over the Southeast in its wake.
On Monday, an embedded, southern-stream upper trof will lift out
of the southern Plains and ride up the ridge. The latest extended
guidance still has the trof axis passing to our north on Tuesday
and moving offshore by early Wednesday. As it does, the upper ridge
will amplify over the Southeast and remain in place for the rest
of the period. At the sfc, broad Canadian high pressure will be
spreading over our region from the NW as the period begins late
Saturday. The center of the high will move over our area on Sunday
and begin to move offshore by late Monday as another cold front
approaches from the west. The front is currently progged to move
through our fcst area on Tuesday and be east of our CWA by early
Wednesday with drier air behind the front. As for the sensible wx,
no significant changes to the fcst were needed, with dry wx for
Sunday and Monday and precip chances ramping up by early Tuesday.
Thunderstorm potential appears minimal at best for the fropa on
Tuesday with little (if any) instability present over our area
on Tuesday. There will likely be a brief lull in precip activity
on Wednesday, however a stronger cold front is expected to impact
the fcst area on Thursday. Otherwise, temps will steadily warm
thru the period with values well-above climatology by day 7.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Cloud cover is noted across the entire fcst
area this evening. Cigs are ranging mostly from high-end MVFR to low-
end VFR east of the mtns. However, MVFR cigs are noted at KAVL.
Moisture will gradually increase ahead of an approaching cold front
tonight into daybreak. KAVL has the potential to see LLWS early
Thursday morning ahead of the FROPA, so have this mentioned in the
TAF. This potential should diminish once boundary layer mixing gets
going. The approaching FROPA will allow cigs and vsbys to gradually
lower overnight into daybreak Thursday. Should see cigs becoming IFR
to LIFR around daybreak, with vsbys mostly ranging from IFR to MVFR,
although brief LIFR vsbys cannot be ruled out. These cigs should
last through much of the 00Z TAF fcst period as the cold front is
not expected to track across the western CWA until late Thursday
afternoon or early Thursday evening. Vsbys should gradually improve
outside of SHRA/TSRA Thursday afternoon. Confidence remains low
regarding the exact timing of the line of convection as CAMs are not
in agreement. Plus, there is the potential for showers and possibly
isolated thunderstorms well ahead of the main line of convection.
So, went with PROB30s for SHRA during the morning to early afternoon
hours Thursday, and prevailing SHRA with VCTS for locations east of
the mtns during the afternoon and early evening hours. However, went
TSRA late Thursday afternoon into early Thursday evening at KCLT.
Should see cigs and vsbys gradually improving towards the end of the
00Z TAF fcst period as the FROPA progresses eastward. Terminals
could see MVFR cigs by early Thursday evening.
Outlook: A cold front will move east of the region Thursday night,
producing gusty NW winds and snow showers in the mountains Friday
and Saturday morning. Dry high pressure returns for the rest of the
weekend.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...JPT
NEAR TERM...AR/MPR
SHORT TERM...JDL
LONG TERM...JPT
AVIATION...AR
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
916 PM EST Wed Jan 11 2023
.SYNOPSIS...
An area of low pressure will move northeast through the region
tomorrow, bringing rain and a few thunderstorms to the area.
Colder air is expected by tomorrow night, with snow showers
going into the day on Friday. Dry weather is expected over the
weekend, with temperatures slightly below normal.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Low level moisture remains abundant across our CWA with a warm
front draped just south of the OH River. Main concern overnight
will be impacts from fog, which could be dense at times (quarter
mile or less) for some locations. Recent trends in observations
have shown visibility bouncing around, but the lowest
visibilities do remain in our eastern IN / western OH counties.
Will consider issuance of Dense Fog Advisory if there becomes a
more consistent signal for widespread dense fog in that area.
For now, have kept just an SPS mention for patchy dense fog
development, but many locations along/NW of I-71 may will have
reduced visibilities of one mile or less tonight into early
Thursday morning.
Continued to keep a drizzle mention in the grids as several
ASOS/AWOS stations show this weather type, and several mPING
reports indicate drizzle presence as well. Periods of drizzle
will be possible for the better part of the night.
Lows remain pretty mild in the middle 40s to lower 50s. Non-
diurnal temperature structure in place overnight, with temps even
slightly increasing overnight, especially across our southern
half of the CWA.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
On Thursday morning, a gradually strengthening area of surface
low pressure will be moving northeast, generally along the path
of the Ohio River. A strengthening feed of theta-e just off the
surface will bring some elevated instability into the area, as
LLJ forcing and upper divergence aid the development of
widespread showers and embedded thunderstorms. This initial
round of storms will ride NE through the ILN forecast area, with
perhaps some slight diminishing in precipitation coverage
before the surface low and cold front make their way through the
area.
There are several potential concerns with this activity, though
no high-confidence threats as of now. For one, the 12Z model
suite (and 18Z HRRR / 3kmNAM) has generally trended a little
bit further south with the axis of heaviest precipitation -- now
suggesting a swath of 1.0" to 1.5" across the forecast area
near the Interstate 71 corridor. There were a few outlier CAMs
suggesting isolated higher totals. The location of this swath
could still change, as occurred during the forecast phase of
the January 3 event, but current trends suggest some potential
for heavy rain in this area during the 12Z-20Z time frame (and
the majority may be with the elevated activity in the 12Z-16Z
time frame). Compared to the January 3 event, the forecasts are
much lower in magnitude, with lower QPF amounts and lower
precipitable water values (about an inch tomorrow). Overall, the
flood risk is low, as long as the rainfall amounts stay near or
just above an inch. The potential concerns would be if the
heavy rain falls a little further south than currently expected
(NE Kentucky, S Ohio, where the heavy rain fell about a week
ago) or if rainfall amounts anywhere get closer to 2" than 1".
Those will be the factors to watch tomorrow.
There is also a very conditional low-end severe threat in the
far southern sections of the forecast area. The morning activity
will be elevated, and seems unlikely to produce severe weather.
Some of the CAMs (including the 18Z HRRR) suggest some surface
based instability may advect into the southern / southeastern
CWA after 16Z. Temperatures near 60 and dewpoints in the lower
50s are not, from a typical standpoint, particularly favorable
for a severe weather threat. However, with relatively cold air
aloft and plenty of wind energy (typical for January), some
low-end threat for strong or severe storms (primarily wind) may
exist. Any further adjustments southward of the overall
precipitation shield / surface low track would likely shift this
conditional threat out of the area.
Later in the day and into the evening, winds will shift to the
NW (with some 20-25 knot gusts) and additional precipitation is
likely to form in a frontogenesis band behind the surface low.
Based on forecast thermal profiles, this activity will likely
change to snow fairly quickly after 00Z, but amounts are
expected to be light and will be unlikely to measure in most
locations. Any steady light snow will taper off to snow showers
heading into Friday morning.
Temperatures will be non-diurnal through the period, generally
rising ahead of the surface low / cold front, and falling behind
it. That will result in falling temperatures most of the day
Thursday in the far northwestern CWA, while temperatures will
rise much more appreciably in the southeast. A quick drop into
the 30s is expected Thursday night into Friday morning.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Amplified mid level flow with 5H trof over the area Friday. Low
level CAA will lead to steepening low level lapse rates and
scatter snow showers. This along with favorable flow coming off
Lake Michigan will likely lead to minor snow accumulations. GFS
and ECMWF ensemble probabilities for snowfall over an inch
between 20 and 50 percent across the far north. Have forecast
snow accumulation of generally an inch or less across the area.
Expect little diurnal rise of temperatures Friday. Have trended
temperatures a little colder than NBM and therefore adjusted
p-type to more snow Friday. Expect highs from the lower 30s
north to the mid/upper 30s south.
Surface high pressure to build across the area Saturday into
Sunday with dry weather expected across the area. Cold
temperatures several degrees below normal Saturday with highs
from the lower 30s north to the upper 30s south. Readings
moderate above normal Sunday with forecast highs ranging from
near 40 north to the mid/upper 40s south.
Moisture will return as a mid level short wave and surface low
lifts northeast into the Great Lakes Monday/Monday night. This
will bring the potential for more rain showers by Monday
afternoon. With a consistent signal for rain have opted for
likely to categorical pops Monday night. Rain chances diminish
Tuesday with high pressure at the surface and aloft building to
the Ohio Valley.
Rain chances increase later Wednesday ahead of next surface low
pressure system.
Mild temperatures around 10 degrees above normal Monday with
highs from the mid/upper 40s north to the lower 50s south, warm
to between 50 and 55 Tuesday and Wednesday.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Primary complex of showers has shifted east of the terminals,
but a light drizzle will continue for a good portion of the
night, so kept that mention in the tafs for a prolonged period.
Majority of terminals in a favored position to maintain IFR CIGs
through majority of the period, with some LIFR CIGs also
possible, especially at KDAY/KILN.
Visibilities will gradually reduce overnight due to BR. In some
locations, FG may form and reduce vsbys to near 1/2 mile or
less. FG does seem favored at all terminals with the exception
of KCVG/KLUK. Still uncertainty if vsbys would reduce to 1/4
mile or less, but KDAY would be most favored spot, so included
a TEMPO mention for this possibility.
A moderate to heavy band of showers moves in from the southwest
shortly after daybreak on Thursday, which will impact all
terminals. Some thunder may be possible as well, especially for
our southern-most terminals near the OH River. Rain should
become lighter in the afternoon, allowing for some minor
improvement of vsbys back to MVFR. CIGs still likely to remain
IFR/LIFR through most of the daytime hours Thursday.
Winds increase behind the cold front to around 10-15 kts from
the WNW, with some gusts up to 25 kts possible.
Note that while not included yet, some light snow may work its
way in Thursday night.
OUTLOOK...IFR conditions will likely continue Thursday night
into Friday, with MVFR to IFR ceilings persisting into Friday
night.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Hatzos
NEAR TERM...Clark
SHORT TERM...Hatzos
LONG TERM...AR
AVIATION...Clark
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
857 PM CST Wed Jan 11 2023
.UPDATE...
Issued at 854 PM CST Wed Jan 11 2023
Behind the departing low stratus deck, patches of dense fog have
developed just beyond the western and southern peripheries of the
CWA. This fog is expected to progress into the area this evening as
diurnal cooling continues beneath the encroaching mid-high level
deck. Additionally, areas of fog are already evident across parts
of northwest IN, though nothing too dense from what we can see at
the moment. Sometime around 09 or 10Z, winds are expected to
readily pick up to just under 10 mph after veering to northerly on
the backside of the departing low. The stronger winds will likely
do well in dissipating much of whatever fog develops across the
area. Forecast soundings from the RAP and HRRR show fog carrying
on into the morning. However, 10-15 mph winds by daybreak will
make it difficult for fog to persist, at least across most areas.
Therefore, we`re not expecting this to be an issue for the morning
commute, especially not across the Chicago metro. Otherwise, no
additional updates to the forecast. Mid-high level clouds are
beginning to build in north of the warm front which will lead to a
cloudy Thursday ahead featuring some decent rain chances across
the southern CWA in the morning and afternoon followed by some
evening snow chances.
Doom
&&
.SHORT TERM...
Issued at 230 PM CST Wed Jan 11 2023
Through Thursday night...
We have had another March-like day today, with temps over-
performing into the mid 50s from the Kankakee River Valley into
the Chicago metro. Thanks to a rapid thinning of mid-level clouds
earlier in the day, increased sunshine allowed much of the area to
mix through a shallow inversion and stave off some of the
northward advance of lower stratus. This has even fostered a lake
breeze over Lake and Cook counties. A shallow warm front ahead of
a weak surface low near the Quad Cities has thus become rather
diffuse in the CWA. Even so, low stratus has taken hold north of
the boundary in east-central Illinois. Expect this area to lift
northeast into northwest Indiana with some haze and possibly
patches of patchy fog through at least this evening.
Guidance continues to delay Thursday`s phasing of a northern wave
with a stronger southern wave currently shifting into the central
Great Plains. This has now pushed the best focus for appreciable
precip to our far southeast CWA or even outside of the CWA during
the day Thursday. Rather, precip chances for most of the area will
likely be driven by the approaching northern wave acting on
existing shallow low-level moisture. In fact, locations north of
the Kankakee River/I-55 will likely see nothing more than patchy
drizzle. Overall thermal profiles support precip likely remaining
all liquid through the daytime hours.
Modest CAA will lift mixing heights to around 5kft with
associated saturated cloud depths of at least 3kft sufficient for
precip generation area-wide Thursday night. A mix of embedded vort
maxima and a secondary trough rotating around deep cyclonic flow
combined with the CAA will provide necessary forcing. Thermal
profiles favor primarily low-SLR snow given increased mixing from
the CAA, though they may be warm enough for drizzle to mix in
early in the evening. Marginal 850hPa/SST delta Ts also support
lake-enhancement on NNW flow into northwest Indiana, especially
late evening and overnight. Overall, locally up 1" of wet snow is
possible in Lake/Porter counties, with around a quarter inch of
snow possible elsewhere in the forecast area.
Kluber
&&
.LONG TERM...
Issued at 239 PM CST Wed Jan 11 2023
Friday through Wednesday...
Main forecast messages and concerns:
* Continued lake effect snow showers on Friday into parts of
northwest Indiana
* Chance for isolated thunderstorms on Monday
* Well above normal temperatures Saturday PM onward
The weather Friday through early Saturday will be a blip of
seasonable winter chill in a sea of well above normal warmth.
Friday will be blustery as ~1035 mb high pressure builds in from
the northern Plains while deep low pressure tracks from northern
New York into northern New England. Temperatures will only be able
to warm into the low 30s, resulting in wind chills in the teens
and lower 20s. The long fetch of unidirectional northerly winds
gusting up to 30-40 mph will be favorable to maintain lake effect
snow showers into northwest Indiana, particularly eastern Lake
County, Porter County, and northeastern Jasper County, where high
chance to likely PoPs are indicated.
Regarding the lake effect setup, the 850 mb to lake surface delta
Ts and lake induced CAPE are marginal, offset some by respectable
convergence, inversion heights pushing 7kft, and synoptic ascent
still over the region. Could also see some spotty flurries persist
past sunrise Friday away from the lake effect activity. Current
expectation is for the lake effect snow bands to stay mainly east
of downtown Chicago, though it might be close. Quickly falling
inversion heights Friday afternoon will bring lingering snow
showers to an end. Overall marginal thermodynamics should keep
additional accumulation under one inch, with main impacts reduced
visibility and patchy slushy spots on roads.
Surface high pressure will pass to the south Friday night into
Saturday, with the ridge axis shifting overhead likely enough to
result in light to calm winds and favorable radiational cooling as
skies average out mostly clear to partly cloudy. Typical cool
spots west of the Fox Valley in northern Illinois may dip down to
the mid teens, with otherwise upper teens-low 20s (mid 20s
downtown Chicago and Indiana shore). An amplified ridge will shift
east on Saturday, with return warm advection, lack of snow cover,
and a good amount of sun yielding afternoon highs in the upper 30s
to around 40F.
Steady southerly winds on Saturday night will limit the
temperature drop, then brisk southerly flow between low pressure
over the Plains and high pressure off to our east on Sunday will
result in highs in the low-mid 40s despite mostly cloudy skies.
Next period of interest in the forecast will arrive Sunday night-
Monday as the Plains low pressure organizes into a low center
forecast to track near or west of the MS River into Wisconsin.
This will place us in the gusty warm sector, with warm and moist
advection ramping up as large scale ascent increases.
Expecting shower coverage to ramp up late Sunday night and become
fairly widespread on Monday until the system dry-slot sweeps
across later in the day into the evening. The 500 mb trough
approach will cool mid- level temps down below -20C, steepening
mid-level lapse rates, likely enough for some minor MUCAPE and
isolated embedded thunderstorms Monday afternoon and evening. Have
indicated slight chance thunder near and south of I-80 for now.
Pattern Monday favors stratus streaming northward, though still
think highs in the upper 40s to lower 50s are a decent bet.
Cold advection in the wake of the system cold front will merely
cool temperatures down to not as far above normal, with forecast
highs in the low-mid 40s still on Tuesday. Another mid-latitude
cyclone may affect the region toward the end of current day 7
(Wednesday) and beyond, with signs pointing toward a cooler but
not very cold and continued active pattern into next weekend.
Castro
&&
.AVIATION...
For the 00Z TAFs...
MVFR CIGS expanded and now blanket much of the region. Cold front
will move across the terminals overnight tonight with a period of
IFR CIGS expected late tonight into Thursday morning behind the
front. Expect some slow/gradual lifting of the CIGS to MVFR during
the day Thursday, though CIGS will likely remain MVFR through the
TAF cycle.
Nearly calm winds this evening should pick up from the north
overnight behind the cold front. While there could be some
sporadic gustiness overnight, gustiness should become more
prevailing Thursday morning.
Some flurries or light snow showers are possible Thursday evening
toward the end of the 30 hour TAF cycle at ORD and MDW, but
confidence is fairly low so opted to hold off on introducing any
precipitation into the TAFs at this time.
- Izzi
&&
.MARINE...
Issued at 230 PM CST Wed Jan 11 2023
Winds will veer north and strengthen overnight into Thursday as a
deepening low pressure tracks along the Ohio River Valley. A
period of NNW gales to 35 knots are expected within modest cold-
air advection over southern Lake Michigan Thursday afternoon into
Friday morning. The primary focus for more sustained gales will be
into the Indiana nearshore, where a Gale Warning is now in
effect. Along the Illinois nearshore, more marginal conditions
warrant a Small Craft Advisory with a mention for some gale force
gusts at this time.
Kluber
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...LMZ743-LMZ744-LMZ745...4 AM Thursday to
noon Thursday.
Gale Warning...LMZ743-LMZ744-LMZ745...noon Thursday to 10 AM
Friday.
Small Craft Advisory...LMZ740-LMZ741-LMZ742...4 AM Thursday to
10 PM Friday.
&&
$$
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Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
848 PM CST Wed Jan 11 2023
.UPDATE...
Issued at 846 PM CST Wed Jan 11 2023
Keeping an eye on the potential for a couple of shots of impactful
weather over the next 12-15 hours. First up is the chance for
severe weather in southeast MO overnight. Latest surface analysis
depicts a warm/stationary front roughly Effingham, IL to near
Rolla, MO. South of this boundary, steep lapse rates atop a near
isothermal boundary layer should result in at least marginal
elevated instability. The last several runs of the RAP have been
highlighting the potential for 1-2k J/kg of CAPE, whereas the HRRR
has been more modest. Regardless, even just 500 J/kg of CAPE
coupled with very strong effective bulk shear (in excess of 60kts)
may be enough to support a few strong to severe storms as the
upstream cyclone moves through the forecast area. The elevated
nature of these storms will significantly limit the potential for
severe winds or tornadoes, making hail the primary threat. The
most likely timing for any strong to severe storms will be between
midnight and 3am.
The second point of concern is the expected snowfall in Mid-Missouri
tomorrow morning. Latest high-res guidance continues to show a band
of frontogenetically forced precipitation along the back side of the
low beginning around 3am. The very strong forcing coupled with steep
low level lapse rates will support moderate to occasionally heavy
precipitation rates for several hours as the band moves SE through
central MO. The vast majority of the 00z high-res guidance is now
showing pockets of more than 0.5" of liquid precip, largely
focused on an area from Morgan county toward near Hermann, MO.
This precip will begin as entirely rain, but we`re still
expecting snow to mix in beginning around 4am as cold air filters
into the region. The latest RAP and HRRR profiles are only
marginally supportive of snow, so I expect the mix of rain and
snow to persist through the morning. Given this mix of rain and
snow and warm ground temperatures, I think accumulations will be
largely limited to elevated surfaces. The exception will be
beneath the heavier precipitation, where the heavier precip rates
may support occasional transitions to mostly snow. I`m not
confident exactly where this heavier precip will set up, but I do
expect it to result in pockets of 1-2" of snowfall before ending
in the late morning.
BSH
&&
.SHORT TERM... (Through Late Thursday Afternoon)
Issued at 253 PM CST Wed Jan 11 2023
The system that will bring precipitation to the region late this
evening into tomorrow morning is making its way off the lee of the
Rockies.
It is likely that there will be a strengthening of large scale
ascent as the CWA will be in the left exit region of the upper level
jet Thursday morning. A low level jet is expected to strengthen
through the early morning hours, enhancing moisture transport into
the region ahead of the system. A surface low pressure system and
associated cold front is expected to move over southeastern MO
through the morning hours bringing with it precipitation region
wide. Recent guidance has suggested that the deformation zone has
trended south compared to prior guidance.
The key questions with this system continues to be the thunderstorm
and snow potential. 12z guidance is hinting at MUCAPE values up to
1000 J/kg in the southern most portions of the CWA where
isentropic lift is the greatest. Severe weather is not expected
but small hail cannot be ruled out in the strongest storms.
Precipitation will likely start as rain and transition to a rain/
snow mix as temperatures cool towards freezing into south central
MO. Soundings allude to a fine gradient between a cool rain and snow
due to a deep isothermal layer right along 0 degrees C. The
timeframe of accumulating snow will be limited to a 2-4 hour window
at any given location. Accumulation amounts depends on how fast rain
transitions to snow and snowfall intensity. Accumulations on grassy
and elevated surfaces are expected to be up to an inch however
localized higher accumulations cannot be ruled out where the the
heaviest snow falls.
As the deformation zone moves quickly eastward through the morning
and early afternoon hours, the chances of accumulating snow will
cease as temperatures towards the Mississippi River and points
downstream will remain in the mid to upper 30s.
MMG/Gosselin
.LONG TERM... (Thursday Night through Next Wednesday)
Issued at 253 PM CST Wed Jan 11 2023
(Thursday Night - Friday Night)
The continuation of much cooler weather will continue Thursday night
through Friday night. Lows each night are forecast to be in the 20s,
with some upper teens possible Friday night into Saturday morning.
Friday`s highs are forecast to be in the low to mid 30s, a few
degrees below normal for the date and a rarity so far this January.
Mostly dry weather is forecast this period, though did add a chance
of flurries roughly along/east of the Mississippi River overnight
Thursday night. A vorticity maxima is forecast to slide
south/southeast down the mid-Mississippi Valley. Some deterministic
guidance actually shows some light QPF in our south-central Illinois
counties. However, continued low-level dry advection (mixed boundary
layer, relatively high cloud bases) suggests more of a flurry regime
than snow showers.
(Saturday - Sunday)
Model guidance is in good agreement with a mid/upper level ridge
moving across the area this weekend. Rising mid/upper level heights
combined with increasing southerly return flow around a departing
surface anticyclone will lead to temperatures warming back up above
normal. The warmer of the two days will be Sunday, with highs
climbing back into the upper 40s to low 50s across the bi-state area.
(Sunday Night - Wednesday)
An active weather pattern appears increasingly likely next week.
Multiple disturbances embedded with southwest flow aloft will
transverse the mid-section of the country next week. For our area,
both of these systems are likely to stay all liquid given expected
storm tracks across or just south of the forecast area. Given some
lingering dryness and the low flows on some of the mainstem rivers
(namely the Missouri), multiple rounds of widespread rainfall should
be quite beneficial.
The first of the two systems of interest is in the Sunday night -
Monday time frame. This first system is likely to be the further
northwest of the two, with the EPS/GEFS mean track of the surface
low more across the mid-Missouri Valley. Widespread rain showers are
forecast along/ahead of a cold frontal passage. A few thunderstorms
may also be possible in southern sections of the forecast area,
though any severe potential at this time appears minimal given
deeper moisture return (60+ degree dewpoints) stays well to our
south in the lower Mississippi Valley.
The second system is likely to come through Tuesday night -
Wednesday night. However, there is more uncertainty with respect to
both the track and timing of this system as WPC 500-hPa height
clusters show a lot more spread in the pattern across the CONUS.
Early indications are for this system to track further south as the
mean baroclinic zone gets pushed equatorward behind the initial
system. However, even with a further south track, it appears that
most if not all of the precipitation will fall as a cool rain.
Gosselin
&&
.AVIATION... (For the 00z TAFs through 00z Thursday Evening)
Issued at 532 PM CST Wed Jan 11 2023
Confidence remains high that an area of precipitation will move
into the area late this evening and overnight, along with reduced
cigs and visbys. Isolated to scattered thunderstorms are likely in
SE MO and southern IL and I couldn`t rule out a few lightning
strikes as far NE as the STL metro. That said, confidence in
thunder that far north is low, so I`ve left it out of the TAFs.
Cigs should quickly fall to MVFR with the onset of the
precipitation, and guidance has come into strong consensus that
we`ll see IFR cigs areawide by roughly sunrise. Around that time,
we`ll likely see some wet snow begin mix in with the rain in
central MO. We`re also expecting pockets of relatively heavy
precipitation in those areas, but guidance continues to indicate
that these pockets will be predominantly rain. Nevertheless, I do
anticipate there to be an area of accumulating light snow
somewhere toward mid-MO, though I have very little confidence
where exactly it will fall. Should it occur at COU or JEF, visbys
will very likely fall lower that what`s in the current TAFs.
BSH
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
709 PM EST Wed Jan 11 2023
.SHORT TERM...(Through Tonight)
Issued at 256 PM EST WED JAN 11 2023
Water vapor imagery and RAP analysis show a shortwave approaching
Upper MI. This wave has brought deeper moisture over the area and
introduced ice crystals into the low-level cloud deck, changing the
-fzdz that occurred earlier today to -sn. Boundary layer is warm
enough for some -ra as well, at least over s central Upper MI, in
particular closer to Lake MI. Under another day of cloud cover,
temps haven`t risen a lot. Temps range thru the 30s F, with most
areas now above freezing.
With aforementioned shortwave moving e of the area tonight, ongoing
-sn and some -ra will exit during the evening. At the sfc, broad sfc
troffing currently extending from nw of Lake Superior to the Mid-
Mississippi Valley will sharpen up some as it shifts e across Upper
MI this evening. In its wake, light nw winds will shift more
northerly and begin to strengthen overnight, and weak caa will
begin. By 12z Thu, 850mb temps will only be down to -6 to -8C, not
sufficient for pure LES. However, with mid-level troffing over the
area along with relatively deep moisture and low-level flow becoming
weakly cyclonic, weak lake enhanced snow may develop, mainly off of
western Lake Superior as air mass will be coldest there. There is
also weak deep layer q-vector convergence noted over the w,
suggesting some synoptic forcing. In the end, the pcpn may end up
being forced mainly by the upsloping nww low-level flow. Any snow
accumulation will be less than 1 inch. Examination of fcst soundings
does suggest there may be some times where moisture may not extend
to the -10C isotherm, raising the prospect of some -fzdz again. That
potential appears to be greatest into n central Upper MI where there
is more consensus for moisture depth to be a bit shallower. Fcst
will reflect some -fzdz, mainly in that area.
.LONG TERM...(Thursday through Wednesday)
Issued at 256 PM EST WED JAN 11 2023
Key Messages:
-Light lake effect Thursday into Friday
-Quiet weather for weekend
-Next precip maker Monday/Tuesday, potentially messy
While the main bulk of synoptic forcing will stay well south of the
Upper Peninsula, subtle shortwaves in the midlevel flow will help
provide some lift for some snow showers through the end of the week.
850mb cold advection will help bring lake-850mb delta-T`s to
marginal lake effect thresholds, with the northerly surface winds
meaning the highest snow potential will be in the north wind belts.
However, surface layer heights are quite shallow, often around 3kft
or less according to bufkit soundings for Thursday and Friday, and
with dry air aloft, the precipitating layer will be quite shallow
and thus snow totals are only expected to be around an inch or 2,
though north-facing slopes of higher terrain could see locally
higher amounts. Another factor inhibiting snowfall is that soundings
often keep the bulk of the saturation below the DGZ, so a lack of
ice nucleation mayt lead to further freezing drizzle or just light
snow, especially in the east-central UP.
Ridging moves in late Friday, and the subsidence from the negative
500mb vorticity advection and backing winds will spell the end of
precipitation for the weekend. The coolest air of the forecast
period will be Saturday morning, as NBM brings single digits to the
interior west, though some lingering lake clouds could keep
temperatures from bottoming out too much. High pressure and dry
weather will last through Sunday evening.
The next precipitation system is coming to start the next work week
with a shortwave trough passage Monday. Ensemble guidance is
consistently pushing an approx. 1000mb low through the Upper Great
Lakes, though the 06Z GEFS has it pushinhg more towards the southern
Lower Peninsula, which would leave us drier and more prone to post-
low passage lake effect, though the 00Z EPS still keeps the low
track very close to the Upper Peninsula, which given the ENS PWAT
values at 99.5 climo percentiles, could be a very wet system. As the
temperatures are above the ENS 90th climo percentiles, the p-type is
going to be a concern. For now, forecasting rain and snow possible,
and while other p-types can`t be ruled out, left them out of the
gridded forecast for now. Beyond the system, LES is possible but
model solutions diverge enough that confidence is low in any details
beyond. The GEFS has postive temperature anomalies through the end
of next week, but the last several runs have brought negative
temperature and 500mb height anomalies for the last week of January,
so there may be hope for cooler air ahead!
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 709 PM EST WED JAN 11 2023
Flight restrictions will persist for the duration of this TAF period
as light snow continues with a weak low. Visibilities will be
especially bad with fog formation at KIWD and KCMX. LIFR will be
the predominant flight category at those TAF sites with MVFR/IFR at
KSAW by early tonight. Meanwhile, winds will be northwesterly and
strongest at KSAW tomorrow afternoon with sustained speeds above the
12 kt threshold and some gusts up to 22 kts.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 256 PM EST WED JAN 11 2023
Winds are imminently going to fall below 20 knots across Lake
Superior if they have not already done so. Winds remain below 20
knots through Wednesday night. Northerly gusts pick up to 20 to 25
knots Thursday morning, first in the central portions of the lake
and by Thursday evening overspreading Lake Superior at 25 to 30
knots. Gusts fall below 20 knots in the west half Friday morning,
with the east half falling below 20 knots Friday afternoon. Winds
remain below 20 knots until Saturday night, when southerly gusts
pick up to 20 to 25 knots over the east half. Sunday, southerly
gusts may occasionally reach 25 to 30 knots, but fall below 20 knots
lakewide by overnight Sunday into Monday.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...GS
AVIATION...TDUD
MARINE...GS
Area Forecast Discussion
National Weather Service San Francisco Bay Area
324 PM PST Wed Jan 11 2023
.SYNOPSIS...Rain and flooding concerns persist for the North Bay
into early Thursday. A brief break from rain for the Bay Area,
Monterey Bay and Central Coast Thursday, before more rain returns
for Friday into the weekend. Hydro concerns will continue.
&&
...Rain and Flooding Concerns Persist...
.DISCUSSION...as of 01:25 PM PST Wednesday...
Key Points--
* Scattered light to occasionally moderate showers will continue
this afternoon before diminishing tonight.
* Highest amounts through this evening expected in the North Bay
hills where a Flood Watch remains in effect.
* A more impactful system brings a greater risk for heavier rain
rates on Friday morning into the weekend.
* A few thunderstorms are possible on Friday and Saturday with
lightning, heavy rain, and small hail as the primary impacts.
* Gusty winds are possible through this evening and again on Friday
into Saturday. Gusts of 30-45 mph are possible, with higher gusts
in the hills.
* Rain chances persist into early next week.
Discussion--
Today and Tonight:
A focused moisture plume is evident via moisture channel imagery and
extends from near Hawaii towards NorCal. Precipitable water values
within this plume are notable and on the order of 1 to 1.25 inches.
Showers are ongoing across the area this afternoon within a warm
advection regime as a surface warm front lurks offshore. With time
the focus of this plume will shift north with the greater potential
for showers aiming at the North Bay into this evening. This is the
area where the greatest rain totals are anticipated with a Flood
Watch continuing into Thursday morning. Additional rain amounts will
be greatest in the North Bay hills and within the coastal ranges (~1-
2"), with much lower amounts expected in the valleys. There remains
a potential for gusty winds over 45 mph in the hills into this
evening and a Wind Advisory remains in effect. Given saturated soils
it won`t take much of a gust to bring down trees. Hydrologic issues
will persist in and near many of the mainstem rivers where flooding
is ongoing.
SPM
&&
.PREV DISCUSSION...as of 03:55 AM PST Wednesday...
Thursday through Early Next Week:
Thursday will be an interesting day as the upper low and
associated upper level trough off the West Coast deepen/dig. The
question will be how much digging and will the associated moisture
shift/remain north or linger over the North Bay. Most guidance
shifts the moisture/rain northward. However, recent runs of the
HRRR say otherwise. Not totally convinced yet, but the HRRR keeps
precip streaming over the North Bay with no shift northward
Thursday. Obviously this would be a bad scenario as rainfall
totals would pile up. Additionally, this would also coincide with
main stem river crest (Russian River). This will have to be
watched closely. Regardless, the offshore/northern precip will
finally move S and E as the upper trough associated front move
through Friday into Saturday. Upper level jet dynamics and surface
forcing will help generate another round of heavier rain Friday
through Saturday. Can`t rule out a thunderstorm or two. No major
changes to the precip totals: North Bay Valleys 1-2", North Bay
mountains, Santa Cruz mountains, Santa Lucia mountains 2-4", East
and South Bay 0.5- 1.5", and Monterey Bay 0.5-1" .
Storm door remains open as another low pressure moves in from the
west bringing another round of widespread rain to the region
Sunday night into Tuesday.
Hydro - continue to watch Russian River at Guerneville with
flood forecast hitting flood stage Thursday. Flood stage ongoing
for Salinas River at Bradley and forecast for Salinas River
Spreckels later today. Monitor stage for Pajaro River ongoing.
MM
&&
.AVIATION...As of 3:25 PM Wednesday...For the 00Z TAFs. Expect a
continuation of rain throughout our region through this evening
with North Bay ending later into tonight. A mix of IFR/MVFR/VFR
conditions throughout the region, with North Bay terminals having
the least favorable flight conditions and Monterey Bay terminals
having the best conditions. Moderate confidence on visibility for
North Bay terminals overnight through early tomorrow morning, but
expect potential IFR conditions. Expect conditions to slightly
improve overnight with high chances of VFR prevailing for most
terminals by late tonight and North Bay by tomorrow afternoon as
drier conditions return momentarily. High confidence that winds
will decrease over night and become less gusty but low confidence
on exact speed. High confidence that winds will remain southerly
throughout the TAF period.
Vicinity of SFO...MVFR conditions through the evening as showers
continue to linger. VFR conditions are expected tonight through the
remainder of the TAF period. Expect winds to remain breezy until
tomorrow morning with a slight chance of gusty winds tonight into
early tomorrow morning, but had low confidence to include in TAFs
at this moment.
SFO Bridge Approach...Similar to SFO.
Monterey Bay...Expect showers to end early this evening therefore
expect VFR conditions to prevail through the TAF period. Winds are
expected to remain strong with high chance of gusty southerly winds
for Salinas Valley through the TAF period. KMRY winds is expected to
start diminishing overnight and remain light/moderate through the
TAF period.
&&
.BEACHES...Large westerly swell enters the waters Thursday
afternoon leading to large breaking waves at area beaches Thursday
into Friday. West facing beaches will see the greatest impacts
with large breaking waves of 20-25 feet late Thursday afternoon
and evening, before diminishing Friday morning. A High Surf
Advisory is in effect for the Central California coastline from
Thursday afternoon through Saturday morning. Please stay well back
from the water`s edge, and stay off rocks, jetties, and
outcroppings.
&&
.MARINE...as of 03:24 PM PST Wednesday...Gales continue in the
coastal waters through Thursday, strongest in the northern water.
A new, long period westerly swell arrives Thursday bringing
hazardous seas peaking over 20 feet in the outer waters, gradually
diminishing through the weekend.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...Wind Advisory...CAZ006-502>506-508>510-512>518-528>530
Flood Watch...CAZ502>506
SCA...SF Bay
GLW...Pt Arena to Pt Reyes 0-10 nm
GLW...Pt Reyes to Pigeon Pt 0-10 nm
GLW...Pigeon Pt to Pt Pinos 0-10 nm
GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm
GLW...Pt Arena to Pigeon Pt 10-60 nm
GLW...Pigeon Pt to Pt Piedras Blancas 10-60 nm
&&
$$
PUBLIC FORECAST: MM/SPM
AVIATION: SO
MARINE: Lorber
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Area Forecast Discussion
National Weather Service Raleigh NC
850 PM EST Wed Jan 11 2023
.SYNOPSIS...
High pressure will shift offshore tonight as a warm front lifts
north through the area. A cold front will move through central NC
late Thursday night into Friday. High pressure will slowly migrate
eastward from the Mississippi Valley into the Southeast and mid-
Atlantic through the weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 850 PM Wednesday...
One primary change to the forecast with the evening update was to
slightly raise low temperatures across the east. Cloud cover has
moved in faster than expected, which will limit the amount of
radiational cooling that can occur and keep temperatures warmer
overnight. Still think that most low temperatures should occur
between 1-3am areawide, with temperatures then remaining steady or
slightly increasing through the rest of the night.
The other primary change to the forecast is to not go quite as far
east with the potential for light rain and/or drizzle overnight.
Some high resolution models are suggesting that an area of more
concentrated rain could develop between the US-1 and I-95 corridor
around sunrise, but otherwise think that the chance for
precipitation will remain farther to the west overnight. Previous
discussion follows.
As of 240 PM Wednesday...
The afternoon surface analysis showed an area of low pressure over
eastern IA, with a trailing warm front over the OH valley. The warm
front sags south into the TN valley, west of the Appalachians and
stretching from northeast GA into far southern SC. Surface high
pressure was extending into the area from the far northeast US.
North of warm front, dewpoints across central NC were in the upper
30s to lower 40s. South of the warm front, dewpoints were in the 40s
and 50s across AL/GA. Low-level WAA, maximized at 850 mb, is well
evident over the TN valley and western NC. This deck of low clouds
is what will reach the Triad in the next few hours and overspread
much of central NC tonight from the southwest to east-northeast.
High clouds have all but exited into far eastern NC as a weak
disturbance tracks offshore.
Little change in tonight`s low temperatures from the morning update.
Overnight lows will drop into the mid to upper 40s across the
central/west and lower 40s in the east/northeast, about 12-18
degrees above normal. Relative clearing over the Coastal Plain this
evening will allow a brief period of good radiational cooling into
the low 40s. Temperatures will then slowly rise or remain steady
overnight as the low-clouds overspread the area amid the WAA.
Isentropic ascent atop the northward moving warm front will allow
for some patchy light rain or drizzle just about anywhere overnight,
but probably most favored over the northwest Piedmont where a CAD
wedge will remain in place. Any amounts will be light.
&&
.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 240 PM Wednesday...
A vigorous upper-trough over MO/AR early Thu will track east-
northeast into the TN valley and Mid-Atlantic region during the
evening/overnight, reaching the upper Mid-Atlantic by early Fri. At
the surface, low pressure over southern MO/IL will race northeast
into the OH Valley in the aftn/eve and eventually reach upstate NY
early Fri. the system will bring the warm front through all of
central NC in the afternoon, with broad southerly flow into the
evening hours. A cold front will advance through by late in the
period, reaching the western Piedmont by early Fri.
Some patchy light rain or drizzle in the morning should give to dry
conditions into early afternoon, except across the western Piedmont,
where the continued WAA/isentropic lift will favor some scattered
light showers. Low-level thicknesses rise some 30 meters from Wed,
supporting highs about 10 degrees or so warmer than Wed. Cloud cover
may limit the full warmup, but strong WAA may be able to overcome
this and support lower 60s in the west to the upper 60s to lower 70s
along/east of US-1 (15-20 degrees above average). Southerly flow in
the 925-850 mb layer starts out in the 30-40 kt range, increasing to
40-55 kt Thu night in advance of the cold front. As a result, wind
speeds in the 10-15 mph range will increase in the evening between
15-20 mph, along with gusts in the 25-35 mph range.
As for precipitation, the best forcing looks to be from late
afternoon into late evening, from about 4pm until 1-2 am Fri, when
deep upper-divergence from a jet streak combined with height
falls/DPVA combines with strong moisture transport and
frontogenetical forcing. After this time, a dry slot looks to punch
in from the southwest, ending the showers/storms from west to east
by early Fri. A marginal risk (level 1 out of 5) remains across the
western/southern Piedmont for Thu. The shear/dynamics continues to
look very favorable, but the limiting factor continues to be
dewpoints only rising in the west to the mid to perhaps upper 50s.
The 12Z HREF shows the highest probability of SBCAPE greater than
300 J/kg along/west of US-1, though some guidance such as the HRRR
indicates upwards of 500 J/kg of MLCAPE possible in this area.
Further east, dewpoints may mix out into the upper 40s over the
Sandhills/Coastal Plain, limiting any storm potential as the line of
showers moves east. For this reason, have only a chance of thunder
across the west Thu. Prefer the faster solutions of the GFS/CMC/HRRR
for the timing of showers/storms ahead of the cold front, which
matches up with the aforementioned timing thoughts. The NAM-NEST/NAM
appear a tad slow based on the synoptic forcing and showers likely
racing ahead of the actual front (HRRR has been consistent with
this).
The cold front may get hung up along the Appalachians Thu night, but
likely move through the Triad and along/west of US-1 by early Fri.
Overnight lows will range from the low 40s NW to the low 50s SE.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 223 PM Wednesday...
Through the phasing of at least 2/3 prominent shortwave troughs, a
high amplitude long wave trough will dig south into the Eastern US
Friday with the potential for the system to close off over the
Carolinas Friday night and early Saturday before moving offshore.
Friday and Friday night: While the primary pre-frontal convective
band will be in the process of moving out to sea, cannot completely
rule out a lingering shower or two across the far eastern/coastal
plain counties as the lead surface cold front promptly exits the
area around daybreak. Thereafter, episodic strong DCVA rotating
through the area will result in periods of enhanced stratocu and
altocu through Friday night/Saturday morning. A fleeting/passing
sprinkle or flurry is also possible, but model signals are pretty
unimpressive. Friday will be the transition day with the onset of
strong CAA delayed until Friday night. Highs ranging from near 50 NW
Piedmont to upper 50s SE with some steady mild gustiness of 17 to 22
mph through the day. Lows 30 to 35, with some mid/upper 20s in the
colder locations.
Saturday through Sunday: Chilly, below-normal temperatures are
expected over the weekend as the parent sfc high builds into the SE
US through Sunday. Saturday and Saturday night will be the coldest
24 hour period. Highs in the lower/mid 40s north to upper 40s/near
50 south. Lows in the lower to mid 20s, which is several degrees
below normal. Under strong synoptic scale subsidence and warming
aloft, temperatures Sunday moderate every so slightly. Highs in the
mid/upper 40s north to lower 50s south.
Monday through Wednesday: Temperatures will further moderate on
Monday as the sfc high moves off the SE US coast. A glancing shot of
forcing and moisture transport from a shortwave trough moving
through the mid MS Valley and into the Great Lakes region late
Monday and into Tuesday will likely result in a quick hitting, light
precipitation event to central NC during that period, followed by a
return to dry conditions on Wednesday.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
As of 650 PM Wednesday...
24 hour TAF period: VFR conditions at all terminals to start the TAF
period. MVFR cigs will creep into the western terminals (KINT and
KGSO) late this evening and persist through the night. All terminals
could experience MVFR/IFR cigs early Thu morning, roughly between
10Z and 15Z before lifting and scattering to MVFR/VFR between 15Z
and 19Z Thu. Highest confidence in lowest cigs at KINT and KGSO,
lowest confidence forecast at KRDU, KFAY, and KRWI. There is a
possibility KRWI could stay VFR through the period. Brief, spotty
light rain is possible Thu morning. Winds should increase late
morning into early afternoon, with gusts of 25-30 kts expected area-
wide by Thu aft/eve, decreasing a bit after sunset. Fore the most
part expect the line of convection to hold off until after 00Z Fri.
Looking ahead: A period of LLWS is expected ahead of the line of
convection, beginning around 00Z Fri, with a 40-50 kt LLJ still
expected to develop, most likely at KRDU, KFAY and KRWI. The line of
showers/storms should move through central NC from west to east
between 02Z and 09Z Fri, gradually weakening as it progresses
eastward. Reduced cigs and vsbys are possible with the showers,
especially at KINT, KGSO and KRDU. VFR conditions should return to
all terminals by Friday afternoon and prevail through the weekend.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...KC
NEAR TERM...Green/Kren
SHORT TERM...Kren
LONG TERM...CBL
AVIATION...KC
Area Forecast Discussion
National Weather Service Blacksburg VA
1022 PM EST Wed Jan 11 2023
.SYNOPSIS...
A warm front moves north of the region overnight with isolated
precipitation. A cold front crosses the area Thursday with
showers and a few thunderstorms, then gusty northwest winds
behind it for Thursday night into Saturday. Mountain snow
showers are also expected Friday into Saturday.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 1020 PM EST Wednesday...
Minimal changes for tonight...
Coverage of any precipitation overnight is expected to be
isolated and light. Have made minor adjustments to temperatures
based on latest gridded LAMP and RAP guidance, along with
current observations.
Previous discussion...
This warm front lifts north with rain ending by midnight.
Heights and southerly flow will increase behind the warm front
overnight. Along with a thick blanket of clouds, mild
temperatures are expected tonight with lows ranging from the mid
to upper 30s north of highway 460 and lower to mid 40s south.
A sharp trough over the Mississippi Valley may become negative-
tilted as it moves over the Ohio River Valley late Thursday.
The cold front and associated showers will begin to track over
the mountains in the afternoon then east of the Blue Ridge and
into the piedmont during the evening. Frontal forcing and a 50
kts low level jet will have linear convection producing isolated
damaging wind gusts. The area south of a line from Bluefield WV
to Danville VA is under a Marginal Risk for severe weather
tomorrow. High temperatures (mid 50s to lower 60s) for Thursday
will peak before frontal showers enter an area.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 145 PM EST Wednesday
An active period of weather is expected during the short term
period, as a dynamic upper level system seen on water vapor
satellite imagery across the western plains becomes negatively
tilted and sweeps through our area Thursday night. At 00Z Friday (8
PM EST Thur) a cold front should be in our forecast area. The low
level forcing associated with this front combined with PWAT values
150-200+ percent of normal, and strong UVM in place with a 95+
knot upper level jet sweeping through, will allow a line of
showers with perhaps embedded storms to be in the eastern half
of the forecast area. Heavy downpours (long/skinny CAPE profile
at KDAN) and locally damaging winds (0-6km bulk shear values
great than 60 knots), are possible in this short window before
the front exits our CWA.
In the wake of this system, a northern stream system will push
southeast through our area Friday, resulting in a prolonged period
of cold air advection and accumulating upslope snow showers along the
western slopes of southeast WV/southwest VA and northwest NC. With
snow showers expected from early Friday morning through Saturday
morning, even light rates may result in advisory level accumulation
amounts in at least western Greenbrier county, and this will
continue to be highlighted in the HWO.
Gusty synoptic winds are expected, especially in the mountains, late
Thursday night/Friday with a brief period of pressure rises and a
40+ knot 850mb jet. Forecast soundings at TNB indicate winds
will approach advisory criteria and this will also be
highlighted in the HWO.
With the strong CAA, trended toward the colder guidance values for
temperatures.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 1230 PM EST Wednesday...
Confidence continues to increase for rain chances on Tuesday...
While there is general agreement in the deterministic long
range models that an upper level ridge over our area to start
the long term period on Sunday will shift east in response to an
upper level trof passing Tuesday, the EPS, GEFS and CMCE
ensembles show high uncertainty with the amplitude of both the
departing upper level ridge and upper trof. A small majority of
members suggest a slightly less amplified pattern.
Confidence is above average that temperatures during this
period will be above normal, especially later in the long term
period as the NCEP Ensemble 850mb temps are 1 to 2 sigmas above
normal.
As for precipitation, depending on when the precipitation
begins, there is a small chance that the precipitation may
initially start as freezing rain early Tuesday morning in the
Alleghany Highlands/Greenbrier Valley with fairly dry air
initially in place. For a large portion of our area, the
precipitation will begin and end as liquid. With a healthy low
level southwest jet in advance of the Tuesday system will also
have to monitor for the potential for isolated thunder.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
As of 700 PM EST Wednesday...
Dew points and amount of moisture in the atmosphere will
continue to increase tonight as a warm front lifts north through
the Mid Atlantic region. Isolated to scattered light rain along
and north of the warm front will move into central and eastern
Virginia by 03z/11PM. Ceilings will start at VFR in the
4000-8000 ft range and lower throughout the evening down to
MVFR.
A sharp trough over the Mississippi Valley may become negative-
tilted as it moves over the Ohio River Valley late Thursday.
The cold front and associated showers will begin to track over
the mountains in the afternoon then east of the Blue Ridge and
into the piedmont during the evening. Have held off the arrival
of showers until 21Z/5PM or later. Ceilings will lower to IFR
after 15Z/11AM over the mountains and piedmont of Virginia and
North Carolina.
The low level jet from the southwest increases into the 40 to 60
knot range after 15Z/11AM. Some of the wind gusts will work down
to the surface and some LLWS is expected, but not widespread
enough to include in the local TAFs at this time.
Average confidence for ceiling, visibility, wind and timing of
precipitation.
EXTENDED OUTLOOK...
Winds shift northwest Thursday night behind the front and
increase through Friday and Friday night. These upslope
trajectory winds will help maintain rain to snow showers across
the mountains Friday morning through Saturday morning with MVFR
clouds and visibility.
By Saturday afternoon winds veer to the north and the uplsope
ends. Cloud coverage will decrease as well.
A building upper ridge will provide for VFR conditions Saturday
night into Sunday. Although, there could be pockets of late
night/early morning river and valley fog. Monday looks dry and
VFR, but moisture arrive Monday night.
&&
.EQUIPMENT...
As of 1210 PM EST Saturday...
A communication hardware outage at the Lewisburg, WV airport,
KLWB, will prevent automated observation from being distributed
between 7PM and 9AM every night. The restoration time is
unknown.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...AMS/RCS
NEAR TERM...AMS/RCS
SHORT TERM...AS
LONG TERM...AS
AVIATION...AMS/RCS
EQUIPMENT...RCS
Area Forecast Discussion
National Weather Service Shreveport LA
957 PM CST Wed Jan 11 2023
...New SHORT TERM...
.SHORT TERM...
(Tonight through Thursday Night)
Issued at 941 PM CST Wed Jan 11 2023
Going forecast is right on track with some I-30 convection this
evening well out ahead of the front. The west winds are nearing
Paris TX and will zip into our area before midnight. The HRRR is
showing I-20 initiation right in east TX near Shreveport and
quickly moving across nearly all the cwa by daybreak. No changes
needed pops or weather or lows at this point, with limited new
guidance and a sure end to the near record warmth we enjoyed
today. The gusty S/SW winds will begin to veer to W and NW by
midnight in our E TX and OK counties. So far speeds are behaving
with the stronger winds keeping 2 to 4 feet up an no advisory
criteria for now. Storm motion is caught up in that 50KT plus
layer right near the cap, and some hail and damaging wind remain
an overnight threat for any strong thunderstorms, mainly in our AR
counties where moisture will be deeper. /24/
&&
.LONG TERM...
(Friday through next Tuesday)
Issued at 317 PM CST Wed Jan 11 2023
By 12z Friday post-frontal NW flow at the sfc and aloft will
continue to overspread the FA with the progression of the 850mb cold
air advection to the Four State Region. At the sfc, high
temperatures Friday will reflect the passing boundary with highs in
the mid to upper 50s, nearing 60 to the southwest. Overnight Friday
and into Saturday morning, lows at or slightly below freezing appear
likely areawide, with the possibility for upper 20s to exist along
and north of the I-30 corridor. With the idea that we may or may not
hold on to some wind through the overnight, frost potential is still
in question. If calm winds are to prevail, area frost would be
expected.
As the trough departs east Friday evening, an upper level ridge will
set up across the Mountain West, with a sfc ridge advancing
southward ahead of the ridge axis, originating out of eastern
Saskatchewan. The Canadian surface high will set the tone for much
of the weekend keeping conditions dry ahead of increasing rain
chances entering next week. With the sfc high exiting to the south
and east, return flow will be in order for Sunday, with the bulk of
the moisture return on tap for Monday as a sfc low moves east across
the Plains. This would aid the development of PoPs in the forecast
south and west of an advancing warm front moving into the
Mississippi River Valley. For now, can`t rule out a few
thunderstorms. Rain chances look to return once more by mid-week
next week.
Along with the moisture advection, the return to
southerly flow both at the sfc and aloft will allow for a layer of
warm air advection to generate a steady increase in temperatures
through the weekend and into next week, with highs in the mid 70s by
the end of the forecast period.
&&
.AVIATION...
(00Z TAFS)
Issued at 541 PM CST Wed Jan 11 2023
For the ArkLaTex terminals, Approaching cold front is rolling down
the OK/TX Red River valley this evening and gusty winds will be
shifting from S/SE this evening to SW and eventually W/NW before
daybreak. Limited moisture and a solid cap will inhibit convection
coming in, but may eventually develop some showers or even an
isolated thunderstorm before clearing KMLU. High pressure will be
arriving all day Thursday with gusty NW winds settling down gusts
anyway by late day, but still sustained 15-20KT until sunset. /24/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 52 61 36 56 / 20 0 0 0
MLU 57 65 35 54 / 30 10 0 0
DEQ 43 54 30 54 / 30 0 0 0
TXK 49 57 34 54 / 20 0 0 0
ELD 49 59 31 51 / 20 0 0 0
TYR 48 58 35 57 / 0 0 0 0
GGG 49 58 34 56 / 10 0 0 0
LFK 52 62 37 60 / 20 0 0 0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
SHORT TERM...24
LONG TERM....53
AVIATION...24
Forecast Discussion:
At 20Z, water vapor imagery shows our next storm system spinning
over the KS/CO state line. An attendant surface low is noted on
surface maps slightly south of there near the OK panhandle. The
surface low will track across OK this evening as the mid-level low
progresses eastward across southern KS.
With this forecast package, there has been a slight southward shift
in the higher QPF and associated snowfall accumulations with the
better frontogenetical forcing now looking to occur near and south
of Interstate 35 late tonight. Forecast soundings from both the RAP
and HRRR along and north of Interstate 70 are now showing more dry
air between 900 and 700 mb, which should limit overall precipitation
and snowfall amounts. Soundings south of I-35, however, show the
stronger forcing and a more saturated column in the 07Z to 10Z
timeframe. Even with higher snowfall rates in those locations, the
fast nature of the system along with warm surface temperatures will
limit accumulations. Thus, the highest totals are expected to range
from 0.5" to 1.5" inches south of the Kansas Turnpike.
A cooler air mass will then work into the region as a surface
ridge builds in from the north through the end of the workweek.
Strong southerly return flow sets up this weekend with efficient
WAA taking temperatures back to near 60 by Sunday afternoon.
Another system is set to impact the area Sunday night and Monday
as another low tracks across the state. The temperature profile
will be well above freezing through the lower atmosphere so rain
is the expected precip type at that time. Long range models are
also showing some elevated instability, so a few thunderstorms may
also occur.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 528 PM CST Wed Jan 11 2023
VFR conditions exist across the terminals at the moment and will
persist for another few hours before a rain/snow mix moves in
from the west. Precipitation will drop ceilings into IFR criteria
and diminish visibilities at times, especially in heavier snow
bands. A TEMPO group has been kept for any heavier bands of snow
that drop visibilities to a mile. Snow showers will move off to
the east between 9-10z with improving visibilities. Winds will
remain gusty out of the north, gusting up to 35 mph at times. IFR
ceilings will continue through the morning (especially at KTOP and
KFOE) before mixing out to MVFR and VFR status by Thursday
afternoon.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Teefey
AVIATION...Griesemer