Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/25/21
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1037 PM EDT Sun Oct 24 2021
Rainfall is expected to move in from west to east
overnight, tapering to showers from south to north Monday morning.
Highs Monday will range from cool across the north to mild across
the south on either side of a front under cloudy skies. A stronger
system will bring periods of rain, moderate to heavy at times,
Monday night into Tuesday night. Dry weather is expected to return
for Wednesday and Thursday.
.NEAR TERM /THROUGH MONDAY/...
Update...As of 1037 EDT...Clouds continue to thicken and lower
from southwest to northeast over the forecast area. The leading
edge of the warm advection rainfall has reached the Capital
Region and NW CT. We timed the light rain/showers moving into
the entire forecast area between 10 pm and midnight. The lower
troposphere will gradually saturate prior to midnight. The
rainfall will pick up in intensity thereafter, as the isentropic
lift increases ahead of the warm front. Low temps will wet bulb
into the upper 30s to the northeast to upper 40s to the south.
The latest GFS, ECMWF, NAM and HRRR are similar with the
placement of the heavier rainfall basically along and in the
vicinity of I-90 with a third of an inch to an inch expected
with some locally higher amounts over the Berkshires and
northern Catskills based on the 00Z NAM. The rain is expected
will taper off late Monday morning as ridging briefly builds
Previous near term...
The warm front is forecast to move into local area, however the
question how far north will it get. There is high pressure
position to our north across eastern Canada and it`s forecast
to strengthen. The consensus is the boundary should stall just
south of I-90. The thermal gradient across the boundary is
impressive and the weather to the north and south of it will be
quite different. We are expecting to experience a 20-degree
different in temperatures across the local area Monday with
highs in the mid 60s in the mid-Hudson Valley with mid/upper
40s across the southern Adirondacks and southern Vermont.
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
The forecast gets complicated as multiple short waves, northern
and southern stream energy phase with a coastal low developing
off the Southeast Coast by Monday night. The primary, inland,
low will weaken as it moves across PA as the coastal low deepens
as it moves northeastward up the coast. The coastal low will
become the primary low and be drawn back toward the coast Tuesday
near the east end of Long Island and Cape Cod. The low is then
expected to remain fairly stationary (wobble) Tuesday afternoon
and evening with the low expected to begin to move eastward
Rain will once again overspread the area by from the east this
time with heavy rainfall expected late Monday night into Tuesday.
At this time, expecting 2 to 4 inches across western New England
with amounts decreasing as you head westward with 1 to 1 1/2
inches across the western Adirondacks. These amounts could end
up be higher especially east of the Hudson River Valley as there
is uncertainty in exactly how close to the coast the low ends
up. The rain is expected to taper off late Tuesday night. A
flood watch may be needed. There are low to moderate probabilities
of some forecast points reaching minor flood stage. There is
the possibility some points could reach moderate flood stage if
the higher QPF is realized. Also can`t rule out some areal or
Winds will pick up Tuesday and Tuesday in the north-northeast
flow on the back side of the deep low especially across western
New England. Gusts up to around 30 mph are expected.
Expecting lows in the 40s both Monday and Tuesday nights with
highs Tuesday in the 50s below 1500 feet and in the 40s above
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Main headlines for the long-term period will continue to focus on
the continued active/wet weather pattern. Early to mid week, a
second, yet more potent piece of upper energy is expected to
detach/separate from the parent anomalous upper trough over the
eastern Pacific/Gulf of Alaska (GOA) region. At the surface, a mid-
latitude cyclone, associated with the upper level feature mentioned
above will track cross-country during the week ahead becoming
occluded/negatively tilted in the process. Ultimately, this will be
our next rain maker in the Friday-Sunday timeframe.
We start off the period on Wednesday-Thursday, when the ALY forecast
area will be getting a reprieve, albeit brief, from the wet weather
as a narrow surface high pressure moves into the region in the wake
of a departing powerhouse low (discussed in the short-term forecast
period). With subsidence over the area via the narrow surface high,
Wednesday through Thursday will be dry and tranquil with cloud
coverage expected to decrease leaving the area with a mix of clouds
and sun. High temperatures Wednesday and Thursday will top out in
the upper 50s along the river valleys (upper 40s to mid 50s higher
Friday through Sunday, we continue to keep close eye on a mid-
latitude cyclone that has the potential to bring another round of
widespread, soaking rainfall. This system has the potential to
translate to a Nor`easter. According to the latest suite of
guidances, rainfall coverage is expected to increase from southwest
to northeast Friday afternoon into Saturday. Friday night through
Saturday is the time period to when we expect the rainfall to be
heaviest at this time. The storm system as mentioned previously is
expected to slow as it becomes negatively tilted/occluded. As a
result, rain could linger into Sunday before finally moving out
Sunday PM into Monday.
As far as temperatures, highs are expected to top out in the mid to
upper 50s along the river valleys (upper 40s to lower 50s higher
elevations). Low temperatures during the extended period will mainly
be in the 40s (with some 30s in the higher elevations). Overall,
anomalies will run slightly warmer than normal for the period.
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
A warm front will bring rainfall into the region tonight through
tomorrow morning. The rain will taper to scattered showers and
patchy drizzle in the afternoon. A lull in the pcpn is expected
into tomorrow night, before rain moves back in late Monday
VFR conditions will lower to MVFR/IFR levels between 03Z-
06Z/MON with the warm advection rainfall with the rainfall
moving into KGFL/KALB/KPOU/KPSF. Cigs will quickly lower in the
rainfall, and vsbys should follow. Expect widespread IFR
vsbys/cigs to materialize between 06Z-12Z/MON. The flight levels
may even lower briefly to LIFR by 12Z/MON. Expect a gradual
improvement to low MVFR cigs/vsbys in the late morning into
the early afternoon from KPOU northward. KPSF may hang at IFR
cigs until 21Z/MON to 00Z/TUE. We expect KPOU/KALB/KGFL to each
low MVFR cigs in the 1.0-2.0 kft AGL range between 18Z-21Z/MON.
The winds will be light and variable in direction at 5 kts or
less overnight. The winds will vary from east/southeast to
northeast at 4-8 kts in the late morning into the afternoon.
Low- level wind shear will become an issue for KPOU/KPSF 06-14Z
/Mon with a south/southeast LLJ around 30-35 kt moving in
Monday Night: High Operational Impact. Definite RA...TSRA.
Tuesday: High Operational Impact. Definite RA.
Tuesday Night: High Operational Impact. Likely SHRA...RA.
Wednesday: Low Operational Impact. Slight Chance of SHRA.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: Low Operational Impact. NO SIG WX.
Friday: Moderate Operational Impact. Chance of SHRA.
Periods of rain tonight through Tuesday night will keep fire weather
from being a concern. After a brief dry stretch Wednesday and
Thursday, additional periods of rain will be likely Friday into next
Two periods of rainfall are expected early this week. The first will
come tonight into Monday morning resulting in 0.5 to 1 inch of
rainfall. Then, a coastal storm will develop with the potential for
periods of moderate to heavy rainfall Monday night into Tuesday
night. Total rainfall amounts during this second event could range
from 1 to 4 inches, heaviest from the Capital District to points
south and east. There is still considerable uncertainty in the
placement of the low track and axis of maximum rainfall. Latest
MMEFS forecasts based on the NAEFS and GEFS still point to low to
moderate probabilities of some forecast points reaching minor flood
stage. Some spots could reach moderate flood stage if QPF on the
higher end of the solution envelope is realized. Some areal or
flash flooding cannot be ruled out as well.
After a brief period of dry weather Wednesday through Thursday,
another system may bring periods of rain Friday into next weekend.
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
Area Forecast Discussion
National Weather Service La Crosse WI
1030 PM CDT Sun Oct 24 2021
.SHORT TERM...(This evening through Monday)
Issued at 255 PM CDT Sun Oct 24 2021
Early afternoon water vapor imagery showed a strong shortwave
trough across eastern NE/KS with its associated surface cyclone
along the MO/KS border. Regional radar mosaics indicated the well-
advertised rain shield spreading north into northeast IA/southwest
WI. This precip is largely tied to mid-level warm advection and
frontogenesis north of the surface warm front. Overall, guidance
is in very good agreement with this deformation rain shield
continuing to slowly spread north into this evening before
pivoting east overnight, exiting southwest WI around sunrise.
Little in the way of even elevated instability will reach into the
area, so thunder/convective potential remains quite low. The
highest rain chances still should hold near and south of the I-90
corridor, in line with placement of the stronger mid-level
frontogenesis via the RAP fields. Higher probabilities (>50%) for
at least half an inch of rain remain along/south of the MN/IA
border with the NBM indicating 60 to 70% probabilities of at least
1 inch of rain across far southwest WI and adjacent portions of
IA. Due to plenty of dry air to the north and an easterly track to
the trough/deformation band tonight, a sharp cut-off in rain
amounts is likely with potential for little rainfall north of the
I-90 and I-94 corridors.
There also continues to be a signal for strong, gusty winds later
this afternoon into tonight as the pressure gradient tightens
between high pressure nosing into the Upper Midwest and the
surface cyclone passing into central IL. 950-850 mb winds
strengthen to around 40 to 50 kts this evening over southwest
WI/northeast IA, and it wouldn`t take too much mixing to bring
down some of those higher winds. The rain/clouds could limit
mixing, but gusts up to around 40 mph are possible this evening
for southern areas.
High pressure will build over the region on Monday with clearing
skies and seasonable highs in the upper 40s to mid 50s.
.LONG TERM...(Monday night through Sunday)
Issued at 255 PM CDT Sun Oct 24 2021
For the longer term, the attention remains focused on the mid-
week system. In the big picture, the models all remain consistent
and have fairly similar solutions on how the overall pattern
evolves. As the mean long wave trough currently off the West Coast
moves across the Rockies, some of the energy from this system
will stay to the north and move across southern Canada with
another piece of energy in the equatorial side of the long wave
trough forming an upper level low over the Lower Plains. The main
differences between the models revolves around how quickly this
upper level low forms and how much energy will remain in the long
wave trough between the upper level low and the energy over
southern Canada. The 24.00Z ECMWF and 24.12Z NAM and GEM all form
the upper level low Wednesday while the 24.12Z GFS holds off until
Thursday and forms the low over the mid-Mississippi River Valley.
The ECMWF and GEM are in the camp of having less energy north of
the upper level low and actually show a hint of weak ridging from
the departing upper level ridge holding over the area while the
GFS does not show this ridging being more progressive and later
with the formation of the upper level low. No matter when or where
the models form the upper level low, they all end up moving it
off into the Ohio River Valley by the end of the work week with
ridging building back into the Upper Midwest.
The main point of contention between the models based on the
upper air differences is how fast the rain moves into the local
area. With that bit of ridging holding of over the area, the ECMWF
and GEM would suggest that the rain would hold off until
Wednesday night. The NAM and GFS have more support for the
possibility of rain moving in Wednesday with moderate QG
convergence in the 1000-700 mb layer, some weak frontogenesis in
the 850-700 mb layer and up to 2 ubar/s of upglide on the 295K
isentropic surface. There are still a few members of the 24.00Z
ECMWF EPS that support the faster solutions so will plan to hold
onto at least some rain chances on the leading edge for Wednesday.
The rain chances then look to be a good bet for the entire area
Wednesday night into Thursday night before pulling out of the
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1030 PM CDT Sun Oct 24 2021
Cigs: MVFR cigs continue to sit just south of the TAF sites, and
most short term models favor keeping them there. Will continue to
follow suit. The mid level deck will eventually scattering/clearing
out toward 12z Mon. SKC/SCT conditions favored through Tue as the
area comes under the influence of a ridge of high pressure.
WX/vsby: northern fringe of rain shield (to the south) has not
reached KRST/KLSE and doesn`t look like it will anymore -
northeast/easterly winds continues to push drier air into the local
area while the parent low pressure system tracks east.
Winds: tight pressure gradient will keep it blustery/gusty from the
northeast overnight, decreasing and becoming more northerly Mon
Area Forecast Discussion
National Weather Service Charleston SC
858 PM EDT Sun Oct 24 2021
Low pressure will develop off the coast late tonight then push
offshore Monday. A cold front will pass through the area Monday
night into early Tuesday, followed by high pressure through mid
week. A low pressure system is expected to impact the region
later in the week.
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
The forecast is evolving as expected. The core of the pressure
falls offshore are centered just east of Tybee Island. The only
major change that was made for the late evening update was to
increase pops to 70-80% across the Georgia coastal counties,
including the Savannah Metro Area, as high-res guidance along
with the 18z HREF continue to increase the pops along the coast
Surface cyclogenesis will rapidly take shape off the Georgia and
South Carolina coasts tonight as shortwave energy moving across
the Deep South pivots across the Southeast States. 24/23z
surface plots already show a coastal trough beginning to
sharpen across the coastal waters with east to northeast winds
prevailing within 20 NM of the coast and a pronounced veering
of winds to the southeast noted at buoy 41004 over the past
several hours. Surface pressures are also beginning to show up
offshore suggesting the beginning stages of cyclogenesis are
likely already underway. The atmospheric column is quite dry
early this evening with RAP soundings show a bone dry sub-cloud
layer with PWATs averaging less than an inch. A plume of
tropical moisture with PWATs 1.50-1.75" will advect north
overnight as a southwesterly low-level jet intensifies across
Florida and into the South Carolina/Georgia coastal waters.
Shower activity is expected to see a steady uptick over the
Atlantic overnight as the surface low takes shape within the
coastal trough and deep-layered forcing intensifies ahead of
the approaching shortwave and left exit region of a subtropical
jet streak propagating across the northern Gulf of Mexico.
There remains some uncertainty on exactly how far inland the
rain shield will penetrate overnight as the surface low deepens
offshore. The RAP and H3R are much more bullish in pushing
measurable rainfall well inland while the HREF and other CAMs
keep rainfall pinned closer to the coast. Given the way the
guidance tracks the 850-700 hPa moisture plume, suspect a
compromise between the HREF and RAP/H3R is likely the best way
to go until trends can be better established overnight. The
updated forecast pretty much keeps pops in the 20-30% range well
inland pops, but were increased to 70% along the coast through
24/12z. Any meaningful instability will likely remain just
offshore, but some data do show some negative lifted indices
reaching into the coastal counties after midnight as the low
begins to form. A slight chance of tstms was introduced to
account for this. QPF will generally average 0.15-0.45 along the
coast through daybreak. Lows will range from the lower 60s
inland to around 70 at the beaches.
.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
A mid and upper level disturbance will be moving through the area at
the start of the period. Scattered showers and perhaps numerous
showers at the beginning of the period, especially near the coast
will quickly shift off to the north and east as the disturbance
moves quickly into the western Atlantic and takes a swatch of deep
moisture with it. A larger more dominate upper level area of low
pressure over the Ohio Valley will then begin to impact the area
Monday afternoon and into Monday night and this and an associated
cold front approaching the area and then moving into the area could
bring mainly a slight chance of showers and perhaps an afternoon or
evening thunderstorm. Limited moisture and only modest assent
precludes higher rain chances at this time. Drier air moves into the
area behind the cold front resulting in the end of the threat for
precipitation by first thing Tuesday morning. Highs on Monday should
range from the upper 70s at the coast to mainly lower to mid 80s
Then as a deep upper level low develops over the western Atlantic,
high pressure will build into the area for Tuesday and Wednesday
bringing in more seasonable and much drier conditions. Highs will
cool into the lower 70s north to the mid to upper 70s south by
Wednesday. Lows Tuesday night will range from the upper 40s inland
to the upper 50s at the coast Tuesday night.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A narrow high amplitude upper level ridge over the area at the start
of the period will shift east as a deep mid level and initially
negatively tilted upper trough and associated surface low moves from
the Mississippi River Valley eastward to the East Coast. By the end
of the period, it appears the system will be weakening as it moves
into the western Atlantic. There is fairy good model agreement on
the large scale pattern. It appears that clouds will be increasing
and thickening Wednesday night with a threat for showers moving into
southeast Georgia counties after midnight, with decent threat for
showers across the entire area Thursday and Thursday night, possibly
lingering into Friday. There could be a threat for some locally
heavy rainfall. A few thunderstorms could be possible in the south
and along the coast mainly Thursday and Thursday night. However did
not include in the forecast at this time due to uncertainly with
regard to the northward movement of the warm front. Afterwards it
appears a cool dry weekend is in store for the area. Highs mainly
mid to upper 70s Thursday will cool to mainly near 70 by Saturday
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
VFR this evening will give way to light rain and lower cigs
overnight as low pressure develops offshore. The rain looks to
remain fairly light, but could become moderate at times
especially along the immediate coast, including KJZI. Vsbys
were held at 6 miles in light rain at all sites, but a TEMPO
group for 3SM RA BR was introduced at KJZI 10-13z and 4SM at
KSAV 06-09z per latest simulated reflectivity output from the
H3R. Cigs are expected to drop to MVFR at all three terminals,
but will have to watch for possible IFR at KSAV closer to
daybreak as rain clears and some lower clouds and possibly some
fog tries to push in from the west and southwest. VFR should
return to all sites by mid morning.
Extended Aviation Outlook: VFR conditions expected to prevail
through mid week. Chance for flight restrictions in showers will
increase starting on Thursday, possibly lingering into late
Tonight: High pressure offshore the Mid Atlantic will cause
winds to shift out of the southeast late this evening with
speeds around 10 knots. Seas will average around 2-3 feet. A
disturbance will allow numerous showers and possibly a few
thunderstorms to develop just before midnight over the Georgia
waters initially, then expanding northward into the South
Carolina waters by the early morning hours. Low pressure could
develop over the waters by early morning causing winds to weaken
slightly and enhancing the coverage of showers.
Monday through Friday: Light and variable winds will become
southerly across all waters by late Monday with speeds expected to
be no greater than 10 knots except in and near any thunderstorms.
Winds and seas will increase Monday night into Tuesday and then
linger into Tuesday night as a cold front approaches and then passes
through the area. It appears that conditions will remain below Small
Craft Advisory thresholds during this time period. High pressure
will then prevail across the area Wednesday and Wednesday night with
winds no higher than about 12 knots and seas 2-4 feet. A low
pressure system will then impact the region and this will result in
increasing winds and seas Thursday into Friday with a possible
threat for Small Craft Advisories for at least portions of the
coastal waters during this time period.
Area Forecast Discussion
National Weather Service Goodland KS
1000 PM MDT Sun Oct 24 2021
Issued at 850 PM MDT Sun Oct 24 2021
Immediate concerns tonight include the Frost Advisory and threat
for dense fog.
Presently just a few cirrus clouds moving across the area with
temperatures in the middle 30s to middle 40s. Winds were generally
under 10 mph.
A stratus deck currently over northeast and eastern Nebraska is
forecast to back in to our northeast zones around 07z, continuing
to move west toward the CO/KS border by 12z. The stratus deck is
expected to remain along or just inside the CO/KS border through
15z then dissipate quickly from west to east through the rest of
the morning. The expected increase in low cloud cover and cirrus
moving in from the west may prevent low temperatures from reaching
the previous forecast values in the lower to middle 30s which in
turn would prevent the development of frost. At this time the
western portions of Sherman and Cheyenne counties of Kansas would
be void of low cloudiness and have a chance of reaching the middle
30s which may produce some frost. For these reasons I will keep
the Frost Advisory going and let the midnight shift take another
As the stratus moves in from the west visibilities are expected to
fall below one mile and very likely closer one quarter mile which
would require a Dense Fog Advisory. At this time will be holding
off from issuing the advisory and let the midnight shift get some
time to look at newer model guidance before making the final
.SHORT TERM...(This evening through Tuesday)
Issued at 203 PM MDT Sun Oct 24 2021
RAP analysis indicates a potent low pressure system departing Kansas
with high pressure building in over the High Plains. Morning cloud
cover dissipated mid morning leading to clear skies and breezy
winds, as some winds have gusted as high as 35 mph so far this
afternoon. The winds are anticipated to die down around sunset as
diurnal heating wanes and the low moves off into Missouri and
Illinois. Afternoon high temperatures still appear to be on track
in the 60s to perhaps the 70s in spots (especially over Greeley
and Wichita counties). Tonight, low clouds and areas of fog are
expected to increase from the north along and east of Highway 83
from Oakley to McCook. The fog doesn`t look to be as widespread or
dense as last night but a few locales could still get down to
around 1 mile in visibility at times. The fog is expected to lift
mid morning Monday. The other factor to watch tonight is expected
frost development with cooler temperatures. A Frost Advisory has
been issued from midnight through 8am MDT for Sherman, Cheyenne
(KS) and Yuma counties. The fog/cloud to mainly clear sky gradient
looks to lineup across Thomas to Rawlins to Hitchcock counties
leading to more expected clearing and winds less than 10 knots
will lead to frost development for the advisory counties. Guidance
has been a little shaky on how far west the clouds will make it
overnight, so if they do end up further east then Hitchcock,
Rawlins and Thomas may need to be added to the advisory.
Monday, looks to be warmer than today as a SSW wind dominates the
area along with clear skies ahead of the next storm system which
sends a warm front across the area. Winds will be breezy to gusty as
winds may gust up to 30-35 mph through the afternoon as the pressure
gradient strengthens. Afternoon highs are currently forecasted in
the upper 60s through mid 70s across the area. Monday night, winds
stay breezy from the south at 10-20 mph. Overnight low
temperatures are forecasted to be warm (for late October
standards) as they range from the mid 40s to lower 50s under clear
.LONG TERM...(Monday night through Sunday)
Issued at 221 PM MDT Sun Oct 24 2021
The focus in the long term revolves around the low pressure
system moving east of the Rockies and across the High Plains
between Tuesday afternoon and Wednesday afternoon.
Concerns include gusty winds south winds along with the dry and
warm conditions along the eastern Colorado border ahead of the
system Tuesday afternoon and transition to a possibility of severe
thunderstorms Tuesday evening and Tuesday night mainly east of a
line from McCook, Nebraska to Gove, Kansas. High temperatures will
be in the middle 70s to lower 80s ahead of a cold front. RH values
along the Colorado border will drop into the upper teens for 2-3
hours with winds gusting around 30 mph. This will produce elevated
to near critical fire weather conditions for a few hours Tuesday
afternoon. As the cold front moves further east proceeded by the
lift ahead of upper trough, storms develop in the warm sector
where the instability and moisture is more favorable. Most recent
model output suggest the area of severe storms may be east of the
forecast area with additional precipitation developing in the
wraparound on the back side of the system overnight Tuesday night
into early Wednesday morning that moves east of the area by mid
day on Wednesday.
Gusty northwest surface winds continue on the back side of the
system Wednesday and again on Thursday as the low pressure center
at the surface sweeps across the southern plains and lifts out
across the Mississippi Valley area. Dry and cooler conditions with
gradually warming temperatures are expected as the upper ridge
expands eastward across the Rockies and High Plains through the
end of the week and into the beginning of the weekend. Dont
expect any dust concerns with the gusty winds as any
precipitation, depending upon how much the area gets, should keep
the the soil from blowing around.
Late this week, there is a potential for some areas to see near
freezing temperatures during the early morning hours. Confidence
in any one area needing any kind of frost/freeze statement is low
and will have to be reevaluated following the currently issued
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1000 PM MDT Sun Oct 24 2021
KGLD...VFR conditions are expected through 12z then again after
16z. From taf issuance through 12z winds generally from the
southeast approaching 11kts. From 13z-15z stratus and fg/br
remains on track to back in to the terminal from the northeast
producing sub VFR conditions. Winds during this time initially
from the southeast around 11kts but picking up with gusts up to
25kts. From 16z through the rest of the period VFR conditions
return with southeast winds gusting over 30kts. Wind shear
increases after 02z.
KMCK...VFR conditions are expected through 08z then again after
17z. From taf issuance through sunrise winds generally very light
from the east. From 09z-16z stratus and fg/br remains on track to
back into the terminal producing sub VFR conditions. Winds during
this time period will be from the southeast under 10kts. After 17z
VFR conditions return with southeast winds gusting up to 30kts.
From sunset through the rest of the period east-southeast winds
remain around 12kts with wind shear increasing.
KS...Frost Advisory until 8 AM MDT /9 AM CDT/ Monday for KSZ001-013.
CO...Frost Advisory until 8 AM MDT Monday for COZ090.
Area Forecast Discussion
National Weather Service Springfield MO
706 PM CDT Sun Oct 24 2021
Issued at 702 PM CDT Sun Oct 24 2021
Surface low pressure continues to track east-northeast across
northern Missouri with a cold front extending south from the low
across western Missouri. A surface trough/low level convergence zone
also extends south from the low across the eastern Ozarks. The warm
front associated with this low extends east into central Illinois,
thus areas of the Missouri Ozarks east of the cold front are well
into the warm sector of this system.
Two distinct areas of thunderstorms are ongoing at the 00Z hour. A
loose cluster of showers and thunderstorms is located across the
eastern Ozarks. We suspect these storms are slightly elevated as
cloud base observations across this region have been around 5000
feet agl. Large hail will be the primary threat with this activity.
It is possible that a few of these storms could become surface based
as they push out of our eastern counties. If this occurs, we may see
a brief window of increased tornado potential as low level shear
increases owing to a strengthening low level jet.
Meanwhile, we expect thunderstorm coverage and organization to
increase along the cold front this evening as upper level jet energy
digs into the region and the mid levels continue to cool. MLCAPE
values of 1200-2000 J/kg will be in place with deep layer shear of
40 to 50 knots. The 00Z KSGF sounding measured MLCAPE values of 1683
J/kg with 0-1 km SRHs now up to 290 m2/s2.
With increasing linear forcing and cold pool conglomeration, we
think that a broken line of storms will continue to materialize
including the potential for QLCS and supercell tornadoes. The last
few runs of the HRRR support this well with multiple updraft
helicity tracks. The threat for damaging straight-line winds will
also increase throughout the evening with QLCS bowing structures.
The good news is that the cold front will continue to move east at a
good clip with most of this activity out of the eastern Ozarks by 11
PM, thus ending the severe threat.
.SHORT TERM...(This evening through Monday)
Issued at 124 PM CDT Sun Oct 24 2021
Main message: Severe storms are likely early in the period with
supercell thunderstorms. Tornadoes, damaging wind, large hail will
also be possible. Storms will be brief.
Sfc low over northeast KS with a trailing cold front over eastern
KS will shift east over the next few hours. A weakly capped warm
sector ahead of the front has kept convection to a minimum, but
have started to see signs of the cap weakening with weak updrafts
along the MO/KS line. Cold air aloft/height falls/lift with an
upstream low amplitude shortwave over KS will overspread the area
further weakening the cap. Moderate MLCAPE values of around 1500
j/kg and deep layer shear of 40-45kts will support organized
storms/super cells. Will see convection increase in coverage over
the next couple of hours with supercells, and eventually a broken
line of storms develop. Prefrontal storms are also possible, with
some cams showing some prefrontal convection as well as the cap
breaks. All modes of severe weather will be possible. Somewhat
veered near surface flow, does not look the best for tornadoes,
but flow may back somewhat toward sunset, especially over the
eastern cwfa. Will be monitoring the storm environment closely.
Storm cell motion will be quite fast given the winds aloft, and
some will occur after dark over the eastern cwfa before exiting
our eastern counties 10pm-11pm.
.LONG TERM...(Tuesday through Sunday)
Issued at 124 PM CDT Sun Oct 24 2021
Tuesday-Wednesday: Big storm system off the U.S. west coast will
move inland over the next couple of days and out into the Plains
Wednesday. Showers and a few thunderstorms will spread east into
the region Tuesday night and continue Wednesday. Sfc low track
looks to be south of the area over OK/AR with limited instability
this far north. While the severe storm risk looks low, will need
to watch rainfall amounts with possible heavy rain over the region
with the slow moving/high amplitude system.
Thursday-Sunday: The slow moving vertically stacked upper system
and sfc low will shift east of the area with some clouds/precip
lingering into the latter part of the week. Will see a ridge of
high pressure move into the region by the weekend.
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 613 PM CDT Sun Oct 24 2021
A quick moving cold front was pushing through the area this
evening. This front has already pushed through the JLN area and no
additional convection is expected there tonight. The thunderstorms
will affect the SGF area from 23z through 01z and BBG area from
00z through 02z. Mainly expecting VFR conditions outside of
convection and some MVFR to brief IFR within the convection. Later
tonight some stratus is expected to move into the area with
ceilings in the MVFR category continuing into early Monday
Winds will become westerly behind the front and eventually shift
to the northwest and north by Monday morning.
Area Forecast Discussion
National Weather Service San Diego CA
838 PM PDT Sun Oct 24 2021
A cold front moving down the coast tonight will bring rain Monday,
mainly in the afternoon and evening. Strong gusty winds will occur
Monday in parts of the mountains and deserts. Tuesday will be a dry,
cool day, followed by warmer weather and weak offshore flow the
second half of this week.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
Low clouds are developing just off the coast this evening with
high clouds continuing to move east across the northern areas.
Breezy southwest to west winds are ongoing across the mountains
and deserts with gusts mostly below 35 mph. Winds will continue
overnight, then strengthen Monday morning. A wind advisory remains
in effect for the mountains and deserts except the Coachella
Valley Monday morning through early Tuesday morning.
The Atmospheric River is still aimed at northern California,
soaking the Bay Area into the Sierras with several inches of rain
in the past 24 hours. This feature will slowly sag south and lose
steam as it moves into So Cal tomorrow. Everything remains on
track so no changes were made to the forecast.
The elephant in the room is the strong atmospheric river currently
moving through northern California. Once it moves into SoCal Monday,
it will have weakened, but CW3E maps still indicate IVT values of
around or slightly over 500 kg/m/s Monday afternoon over our area
based on the ECMWF/GFS/NAM inputs. ECMWF EFI show effectively record
values for both QPF and surface winds in central California today
though nothing outstanding from LA south. Model time-height cross-
sections show most of the moisture at/below 650 MB along with 850 MB
winds from the west/southwest of 20-30 knots, so that will be
favorable for decent orographic precipitation, though without the
instability and dynamics being fairly brief with the cold front,
precip amounts will not be too impressive at the coast. ENS/GEFS
ensemble members are fairly consistent with each other and run-to-
run with mostly around 0.2" at SAN and 0.4" at SNA, though the
latest deterministic HRRR is showing a little bit higher values
around 0.5" in some coastal locations. Orographic precip will be
greatest in the San Bernardino County Mountains as local values
could exceed 2", though most mountain locations, especially
farther south, will be closer to 1". Given that the nearly-
saturated layer only goes up to about 650 mb, it will be difficult
for the deserts to get anything substantial, but the high deserts
could get up to 0.25" with the lower deserts mostly below 0.1".
Timing will mostly be Monday afternoon to early evening, with
Orange/San Bernardino Counties coming before San Diego/Riverside
Counties. Local wind gust potential of around 55 MPH Monday on the
desert mountain slopes which will warrant a wind advisory for
then. Regarding snow, the freezing level mostly remains at/above
10000 ft MSL when the moisture is in place, with only a drop below
at the end of the storm, so little or no snow will fall on any
roadways, even at Onyx Pass.
After Monday night, the trough of low pressure associated with the
atmospheric river will shift east towards the Rockies while broad
zonal high pressure aloft covers much of the eastern Pacific. That
high will amplify and move east over the western US Wednesday
through Friday. Models are having a tough time past then, with some
troughing or possibly a closed low moving by to the north over the
weekend. Some offshore flow at the surface will occur as well
Wednesay and Thursday, but nothing strong. Daytime highs should
increase to above seasonal normals with ENS indicating some 90s in
the valleys and especially lower deserts by Thursday, with a slight
cooling trend over the weekend. Sunshine should be abundant most of
Tuesday through Friday, maybe Saturday.
250300Z...Coasts/Valleys/Mountains...Low clouds with bases 1500-2500
ft MSL expected to develop along the coast around 06Z Mon, spreading
inland through 12Z Mon. Higher terrain becoming obscured in clouds
after 12z Mon. RA expected to start in Orange County around 21Z,
with isolated SHRA possible ahead of the main front as early as 17Z
Mon. RA will move from northwest to southeast, reaching San Diego
County around 00Z Tue. Vis will be reduced to 2-4 SM and cigs may
become locally under 1000 ft MSL at times in areas of RA. Dry
conditions expected for all areas after 06Z Tue. Bases 3000-5000 ft
MSL expected overnight Tue.
Strong southerly winds with strong up and downdrafts
along with wind shear near mountains and adjacent mountain slopes
Monday as winds increase to 20 to 30 knots with gusts approaching 50
knots at times. Gusty southwest winds expected at coastal TAF sites
after 21Z Mon.
Deserts...SCT-BKN high clouds AOA 20000 ft MSL through 00Z Mon.
After 00Z Mon clouds with bases 5000-7000 ft MSL, showers, and
deteriorating conditions expected through Tue AM. Gusty north to
northwest winds expected after 21Z Mon. Gusts 25-30 kt
expected. Strong up and downdrafts near the mountains.
An approaching storm system will bring gusty southwest winds, that
will transition to northwest winds after 5 PM Mon. Gusts of 20-25
knots expected in the outer waters and closer to 20 knots across the
inner waters Monday afternoon and Tuesday. Combined seas of 6-10 ft
expected, highest in the outer waters. Please see the Small Craft
Advisory and Coastal Waters Forecast for more information.
A long period west swell and a long period south swell will result
in high surf and a high rip current risk at all beaches Monday
through early Wednesday. Surf of 6 to 8 feet is expected, with sets
up to 10 feet possible in southern San Diego County. Please see the
High Surf Advisory for more information.
Skywarn activation will not be needed tonight, but may be
CA...Wind Advisory from 10 AM Monday to 2 AM PDT Tuesday for Apple
and Lucerne Valleys-Riverside County Mountains-San
Bernardino County Mountains-San Diego County Deserts-San
Diego County Mountains-San Gorgonio Pass Near Banning.
High Surf Advisory from 11 AM Monday to 3 AM PDT Wednesday for
Orange County Coastal Areas-San Diego County Coastal Areas.
PZ...Small Craft Advisory from 11 AM Monday to 5 AM PDT Tuesday for
Coastal Waters from San Mateo Point to the Mexican Border
and out to 30 nm-Waters from San Mateo point to the Mexican
Border Extending 30 to 60 nm out including San Clemente
Area Forecast Discussion
National Weather Service Shreveport LA
1016 PM CDT Sun Oct 24 2021
Convection has been slow to develop along the approaching cold
front this evening, with the front reaching from near a FSM, to
just NW of Hugo, to DAL and just N of CPT line as of 03Z.
Instability ahead of the front has begun to wane, with SBCapes of
only 500-1000 J/Kg, contributing to the lack of strong updrafts
which has limited lightning this far this evening. Instability
will remain rather meager as we continue through the overnight
hours, with the strongest forcing beneath the shortwave trough
expected to remain just NNE of the region over Cntrl/Ern AR. Still
can`t rule out an isolated strong storm over Nrn McCurtain County
OK during the next hour, and thus will allow the current Tornado
Watch #532 to remain in effect until its 04Z expiration, but have
taken out severe wording for the Nrn zones overnight, while also
lowering pops slightly to mid and high chance for the Nrn zones
as well. This convection should gradually diminish late tonight
as the best forcing slips ESE into the Mid-South region, with the
front reaching the I-20 corridor of E TX/N LA around daybreak
Monday. Only very minor adjustments were needed to the forecast
min temps, but did delay the onset of the increased cloud cover
given the lack of cigs currently over the Wrn half of the region.
The front remains progged to drift S into Cntrl LA and Deep E TX
Monday afternoon before pulling up stationary, resulting in a
gradual clearing of cigs over all but Lower E TX through the day.
Did maintain slight chance pops through mid-morning through for
portions of Srn AR/Nrn LA along the front, with drier conditions
trending during the day as the deeper wedge of drier air advects
SSE in wake of the fropa.
Zone update already out...but will send another zone update
shortly after 04Z with the expiration of the TOR Watch.
.PREV DISCUSSION... /issued 707 PM CDT Sun Oct 24 2021/
VFR conditions will continue through the evening, although MVFR
cigs are expected to develop after 06Z Monday across portions of
Deep E TX/N LA, and gradually lower through daybreak ahead of a
cold front that will progress SE into the region by/after 06Z. Sct
convection has already developed along the front this evening
across Ern and SE OK, which will shift ESE into SE OK/adjacent SW
AR between 02-06Z. These storms should affect TXK between 05-07Z,
and ELD between 07-10Z, producing gusty winds to 30+kts, locally
reduced vsbys, and low MVFR cigs, before the convection gradually
weakens just prior to daybreak as it enters portions of NCntrl LA.
Have held off thunder mention for MLU given the lower confidence
in the convection reaching this terminal, but will be monitored
for possible amendments overnight. In addition, areas of IFR/LIFR
cigs and FG should develop after 08Z across portions of Deep E and
SE TX, affecting LFK through 14Z before lifting. The front will
reach the I-20 corridor of E TX/N LA between 12-15Z Monday, with
cigs scattering out with the passage of the front, as it enters
Cntrl LA/Deep E TX by early afternoon before becoming stationary.
Thus, any remaining cu field will diminish during the afternoon,
although some will linger across portions of Lower E TX and
NCntrl LA through the end of the TAF period. S winds 4-8kts this
evening will become WSW around 5kts after 06Z. Winds will then
become NNE 5-10kts with the fropa after 12Z. /15/
.PREV DISCUSSION... /issued 410 PM CDT Sun Oct 24 2021/
Zone update just sent for the issuance of TOR Watch #532 for
McCurtain County OK. The latest visible satellite imagery
indicates an area of agitated cu developing to our NW over ECntrl
and Srn OK, along a cold front steadily progressing E across the
state into NW TX. It still will be some time before the narrow
line of convection develops and affects McCurtain County, with the
latest HRRR depicting this not occurring until around/after 02Z.
While not particularly high, enough of a threat warrants a
watch as isolated strong to severe convection may affect the NW
and Nrn zones late this evening into the early morning hours
Monday. Will continue to monitor the evolution and progression of
the convection for a possible extention of the watch into SW AR
late this evening.
.PRELIMINARY POINT TEMPS/POPS...
SHV 69 89 62 85 / 20 10 0 0
MLU 69 89 55 81 / 30 20 0 0
DEQ 58 83 53 79 / 40 10 0 0
TXK 65 85 58 82 / 30 10 0 0
ELD 65 84 52 78 / 50 20 0 0
TYR 67 89 66 87 / 10 10 0 0
GGG 69 89 62 87 / 10 10 0 0
LFK 69 91 67 88 / 10 10 0 0