Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/27/20
Area Forecast Discussion
National Weather Service Fort Worth TX
628 PM CST Thu Nov 26 2020
...New Short Term, Aviation...
.SHORT TERM... /NEW/
/Tonight through Friday Night/
A cold front continues to sweep south through the Plains
this evening and will likely advance south of the Red River by
midnight. Initially, the front will slide through without much in
the way of precipitation across North Texas. Winds will turn to
the north and there will be an increase in cloud cover. As the
front approaches Central Texas, however, low level moisture
coupled with increasing large scale ascent will result in the
development of precipitation (showers and storms). Pockets of
fog---some dense---will be possible near and just behind the
front as low level moisture convergence occurs. The most probable
area for fog will be across East Texas and the Brazos Valley.
Instability will steadily increase with MUCAPE values approaching
800-1000 J/kg. With mid-level flow increasing, a sufficient combo
of shear and instability may exist to facilitate strong to
marginally severe storms. At present time, the primary concern
would be hail, though this threat looks greatest farther south
into the Texas Coastal Plain and Hill Country. We`ll continue to
monitor trends, however, as latest HRRR suggests that a few strong
to near severe storms could be possible near and south of the
I-14/US HWY 79 corridor in our forecast area.
As 925-850mb WAA increases across Central TX and the Big Country,
I anticipate additional showers and storms will develop later in
the day. I`ve nudged PoPs upward some from the previous forecast
given the strong large scale ascent. Decent surface pressure rises
upstream will also drive a breezy north wind and speeds will range
between 10 and 20 mph. It`ll also be cooler Friday with highs in
the 50s and 60s.
Bain
&&
.LONG TERM... /Issued 134 PM CST Thu Nov 26 2020/
/Friday night through next Thursday/
The cold front will be well to our south near the TX SE Coast,
but the breezy north winds are expected to continue Friday night
into Saturday. Rain chances will also increase, especially across
the Central TX zones, where better moisture and ascent is
forecast. Overnight lows Friday night will be a few degrees cooler
than tonight`s temps.
The upper closed-low upstream of the cold front will slowly move
across the southern plains over the weekend. Plenty of isentropic
lift and rich moisture ahead of this system will bring widespread
rain chances through at least Sunday morning. Rainfall rates will
remain on the light side, but we can`t rule out some brief periods
of moderate/heavy rain. Most of the enhanced rainfall and
convection will remain across the Gulf Coast. Rainfall totals for
our area are expected to remain between half an inch to around 1.5
inches through this period. Saturday`s temps will stay on the
cool/chilly side due to the rain, breezy north winds, and cloudy
skies. We`re looking at highs ranging from the mid 40s (western
counties) to mid 50s (eastern counties).
Both medium and long-range models are pretty consistent on showing
the upper level low moving to our east on Sunday. Behind that,
another surge cold cold advection will travel southward as we head
into next week, keeping the steady north winds and well below normal
temps. Many locations will see light freezes Monday morning, with a
few spots across the northwest reaching the upper 20s. The
coldest night still appears to be Monday night into Tuesday
morning, where widespread freeze is in the forecast. Temperatures
will range from the upper 20s to lower 30s. If the forecast
verifies, we are looking at the first freeze of the season for
DFW Airport, and the third freeze for Waco.
Most of our area will remain in this cool/chilly and dry weather
pattern through mid-week before we see the next system. At this time
it looks like rain chances will return to North and Central TX next
Thursday and Friday with the approach of another cold front.
Sanchez
&&
.AVIATION... /NEW/
/00 UTC TAF Cycle/
Concerns---FROPA and ceiling trends.
VFR will prevail over the next 4-6 hours across area aerodromes
before stratus invades. At North Texas TAFs, post-frontal MVFR
stratus is anticipated everywhere in the 08-12 UTC time frame.
The exception will be AFW where dry air will maintain VFR. The
window for MVFR (cigs around 1200 feet) looks to be on the order
of 2-4 hours elsewhere, with DAL likely experiencing the longest
breadth of cigs near 1200 feet. In addition to MVFR cigs,
northerly winds will increase to around 12-15 knots. Some gusts to
near 20 knots are possible. The potential for SHRA or TSRA looks
limited, but will need to be monitored for the 30 hour D/FW TAF in
future forecasts.
At Central TX, MVFR stratus will develop in the southerly flow
regime. As the cold front slides southward, it`ll interact with
greater moisture for a longer duration stratus event. Lift will
also result in pockets of SHRA with embedded TSRA. The best
instability will reside south and east of ACT and I`ll omit TSRA
from the TAF at this time. Northerly breezes around 15 knots are
also expected here.
Bain
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 51 59 46 49 41 / 5 10 20 60 70
Waco 54 62 50 52 41 / 10 50 50 80 60
Paris 50 59 43 51 41 / 5 5 5 30 80
Denton 45 60 42 48 37 / 0 5 20 60 60
McKinney 49 59 44 50 40 / 5 5 10 50 70
Dallas 52 61 48 50 42 / 5 10 20 60 70
Terrell 55 61 47 50 41 / 10 10 20 50 70
Corsicana 58 64 52 54 44 / 20 40 40 70 70
Temple 56 62 49 52 39 / 20 70 60 80 50
Mineral Wells 45 59 42 47 37 / 0 10 30 80 50
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Lincoln IL
930 PM CST Thu Nov 26 2020
.SYNOPSIS...
Issued at 233 PM CST Thu Nov 26 2020
Dry weather and seasonable temperatures will dominate central and
southeast Illinois into this Thanksgiving weekend. Lows overnight
will be in the 30s. Highs Friday will be in the mid to upper 40s
in central IL and lower 50s in southeast IL.
&&
.UPDATE...
Issued at 922 PM CST Thu Nov 26 2020
Updated the forecast for some adjustments in sky cover and cooler
lows west of I-57 where low clouds cleared, allowing quicker temp
drop. Low clouds with bases of 1.5-2.5k ft were east of I-57 at
mid evening and slowly eroding eastward. Thin cirrus clouds
covered rest of central and western IL, with another batch of low
clouds over much of WI, central IA and se MN. These clouds were
behind a cold front that was over se WI to near the IA/IL border.
Temps have cooled to mid to upper 30s west of I-57 where low
clouds have clearing with Galesburg and Macomb at 34F and
Jacksonville down to 33F.
Latest CAMs bring cold front southeast toward the IL river by
sunrise Fri, and near I-57 by noon Friday. Models show some
increase in low clouds overnight in central IL ahead of
approaching cold front with fairly light south to sw flow. Also
the 00Z ILX sounding shows a strong inversion from 1.8-3k ft which
could trap low level moisture and HRRR, RAP and GFS lamp data
showing patchy fog developing overnight east of the IL river, and
mainly west of I-57. Will need to watch for this possible fog
development overnight into early Fri morning as temps already
close to dewpoints. Lows tonight in the low to mid 30s west of
I-57 and upper 30s to near 40F from I-57 east, mildest readings
near the Wabash river where low clouds likely remain thru the
night and into Fri morning.
&&
.SHORT TERM...(This evening through Friday)
ISSUED AT 233 PM CST Thu Nov 26 2020
18z surface map indicated a weak cool front from northeast into
central IA, while 1020 mb high pressure was centered over the
lower Mississippi Valley. Resulting southwest low level flow was
working to erode the low level cloud deck, and had advanced east
of the IL River by 2 pm. Expect clearing to continue through much
of the central CWA into this evening, then cloud cover should
redevelop ahead of the advancing cold front. These clouds should
persist well into Friday morning, then begin to decrease from the
west towards midday. Due to the rather persistent cloud cover, low
diurnal temperature ranges will be observed with lows in the
mid/upper 30s tonight, and highs in the upper 40s Friday.
.LONG TERM...(Friday night through Thursday)
ISSUED AT 233 PM CST Thu Nov 26 2020
Cool and quiet weather will be seen Saturday as 1025 mb high
pressure builds across central and southern IL.
The pattern begins to turn more active Sunday, when a northern
stream wave pushes a dry cold front into the area. Meanwhile a
southern stream disturbance will move into the lower Mississippi
Valley. 12z guidance still shows varying solutions on how quickly
the waves will phase, but the overall deterministic and ensemble
solutions favor this process occurring from the Ohio Valley
towards the Appalachians. This would bring higher impact winter
weather to Indiana and points east/northeast Sunday night through
Monday. NBM guidance brings chances for light rain into the
southeast third of the CWA Sunday evening, changing to snow after
midnight as the column cools below freezing behind the front. Any
minor accumulations would diminish on Monday east of I-57. Still
plenty of time for changes in the track of this system, as the
northern stream energy is still off the Pacific coast.
Higher confidence that a period of below normal temperatures will
impact the area Monday through Wednesday while low pressure
occludes over the eastern Great Lakes. This should result in highs
in the 30s with breezy northwest winds.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 559 PM CST Thu Nov 26 2020
Stratus/stratocumulus clouds with MVFR ceilings 1.5-2k ft
affecting DEC and CMI early this evening while low clouds have
scattered out at SPI and BMI and clear of low clouds at PIA with
some passing cirrus clouds. DEC on western edge of low clouds may
see these clouds scatter out to for a time next few hours. But
broken to overcast MVFR clouds likely to return to central IL
during late evening/early overnight. Some models like HRRR even
show more fog developing after 08Z/2 am overnight and for now
added MVFR vsbys from 09-15Z. A cold front over se parts of WI/IA
into nw MO to push se toward IL river/PIA by 12Z/6 am Fri and to
DEC and CMI by late Fri morning and should pass thru dry. MVFR
clouds to scattered out behind the cold front by Fri afternoon.
South to SW winds 5-10 kts early this evening to weaken to around
5 kts next few hours. Winds switch NW with passage of cold front
during Fri morning at 5-10 kts.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...07
SYNOPSIS...25/07
SHORT TERM...25
LONG TERM...25
AVIATION...07
Area Forecast Discussion
National Weather Service Jacksonville FL
927 PM EST Thu Nov 26 2020
...DENSE FOG LATE TONIGHT AND EARLY FRIDAY MORNING IN THE
SUWANNEE VALLEY AND INLAND SOUTHEAST GA...
.UPDATE...
Evening surface analysis depicts a weakening cold front stretching
from the Mid-Atlantic coast southwestward across the southern
Appalachians and through the Deep South to the Louisiana and Texas
Gulf coast region. Aloft...fast zonal flow prevails as a
strengthening subtropical branch of the jet stream is nosing into
our region from the northern Gulf coast. Meanwhile, a potent
shortwave trough was diving southeastward from the Canadian
prairies through the Dakotas and troughing was cutting off from
the main flow over the Desert Southwest. Latest GOES-East derived
Total Precipitable Water imagery indicates that deeper moisture is
gradually advecting into our region from the west ahead of the
decelerating frontal boundary, with PWATS of 1.3-1.5 inches in
place across our area and values in excess of 1.5 inches noted
over the western FL panhandle. Scattered convection that developed
along a prefrontal trough ahead of the upstream cold front this
afternoon over the Suwannee Valley and along the Altamaha/Ocmulgee
Rivers has since dissipated, with debris cloudiness thinning out
along the I-10 corridor and coastal southeast GA. Meanwhile,
GOES-East nighttime infrared imagery already shows an expanding
area of low stratus cloudiness to the west of the Suwannee River
in north FL and west of I-75 in south GA. Temperatures and
dewpoints at 02Z were only slowly falling through the 60s
across our region.
Support aloft for the frontal boundary to our northwest has
weakened, while shortwave energy embedded within the strengthening
subtropical branch of the jet stream was developing scattered
convection along the boundary over the lower Mississippi Valley.
Debris cloudiness from this convection will migrate across our
skies after midnight, which may impact the extent of dense fog
formation for locations south of I-10 late tonight. Short-term,
high resolution guidance such as the last several HRRR runs as
well as the 15Z SREF suggests that low stratus ceilings will
advect eastward into the northern Suwannee Valley and inland
southeast GA after midnight and will expand eastward towards
coastal southeast GA and along the I-10 corridor during the
predawn and early morning hours. Low stratus and fog may arrive at
or just after sunrise in metro Jacksonville and along the
southeast GA coast, with lower confidence in fog reaching southern
portions of the St. Johns River basin and coastal northeast FL.
Shortwave energy migrating into the FL panhandle from the west
late tonight could also spark a few showers towards sunrise just
ahead of the front near the Altamaha/Ocmulgee Rivers. Lows tonight
will only fall to the 60-65 degree range as surface winds
decouple around midnight.
Troughing aloft digging southeastward from the Upper Midwest and
the western Great Lakes region on Friday will nudge the frontal
boundary southward towards the Altamaha and Ocmulgee Rivers by
sunset on Friday. Widely scattered showers and possibly a few
thunderstorms will be possible on Friday afternoon ahead of this
front, mainly for inland locations north of I-10. Increasing
multi-layered cloudiness should keep highs in the upper 70s for
most of southeast GA, with lower 80s elsewhere, except mid 80s for
north central FL. An afternoon sea breeze will move slowly inland
from coastal locations, with isolated convection also possible
along this boundary during the mid to late afternoon hours.
&&
.MARINE...
A weakening cold front will move slowly southeastward on Friday
and will cross our coastal waters early on Saturday. High pressure
will briefly build over the Ohio Valley in the wake of this front
on Saturday night and will then progress eastward, moving off the
Mid-Atlantic coast by Sunday afternoon as low pressure rapidly
strengthens over the lower Mississippi Valley and begins to
accelerate northeastward. A brief period of onshore winds are
expected in the wake of the weak frontal passage on Saturday night
and Sunday. Showers and thunderstorms will then increase on Sunday
afternoon as the front returns northward. Low pressure will
continue to deepen as it traverses the Appalachians on Sunday
night and Monday morning, driving a strong cold front across our
waters by midday on Monday. A few strong thunderstorms will be
possible on Sunday night and early Monday ahead of this front,
with Small Craft Advisory Conditions developing offshore. Strong
low pressure will then remain nearly stationary over the Great
Lakes region through midweek, with breezy offshore flow continuing
over our waters and elevated seas prevailing offshore.
Rip Currents: A lingering long period easterly ocean swell will
likely keep a low-end moderate risk at the northeast FL beaches
on Friday.
&&
.PREV DISCUSSION [708 PM EST]...
.NEAR TERM [Through Tonight]...
A broken pre-frontal squall line of showers and isolated
thunderstorms is moving eastward into inland southeast Georgia and
Suwannee Valley this afternoon into evening. A few stronger storms
will be possible given elevated shear and marginal diurnal
instability as a nose of upper 60s dew pts edges inland across the
Suwannee River Valley from the GOMEX this afternoon. Potential
strong storm hazards today include small hail with below climo 500
mb temps of -13 to -14 degC under 45-50 kts within the hail growth
zone. There could also be some gusty winds from stronger
downdrafts with 40-50 mph at the surface and 0-6 km shear near 40
kts (38 kts TAE and 43 kts JAX 12z RAOBs). Low level subsidence
will keep mostly dry conditions over northeast Florida. With the
loss of diurnal instability, showers will come to an end later
tonight. Widespread patchy fog will be possible tonight into the
early morning hours with the increase of low level moisture.
Locally dense fog will also be possible. Lows tonight will be
above normal in the 60s.
.SHORT TERM [Friday Through Saturday Night]...
A weak cold front will stall over southern Georgia on Friday and
drift southward into north Florida on Saturday. Embedded weak
impulses will move through zonal flow aloft contributing to the
development of scattered showers and isolated storms mainly north
of the I-10 corridor. Temperatures will remain above average with
temperatures closer to average on Saturday.
.LONG TERM [Sunday Through Thursday]...
On Sunday, an upper low over the TX/OK border will move eastward
as a surface low deepens over the lower Mississippi valley. The
lows will lift northeastward toward the southern Appalachians by
Monday morning. This will cause the frontal boundary over north
Florida to lift northward as a warm front on Sunday. Widespread
rainfall with embedded thunderstorms will affect the area with
isolated strong storms possible. A strong cold front will then move
through the region Monday morning bringing a much colder and
drier airmass for early next week. Temperatures will drop below
normal and could bring our first freeze of the season. Lows will
drop into the 30s Monday night and Tuesday night. Widespread
freezing temperatures will be possible across southeast Georgia
Tuesday night. Brisk winds will likely produce windchill
temperatures in the upper 20s and 30s.
.AVIATION...
[Through 00Z Saturday]
VFR conditions will prevail through at least 05Z. Low stratus and
fog will overspread the Suwannee Valley and inland portions of
southeast GA after 06Z, with LIFR ceilings of 200-400 feet
reaching GNV towards 09Z and VQQ towards 10Z. These low stratus
ceilings and fog should then reach JAX and CRG between 11Z-12Z.
Confidence was too low to include the coastal terminals of SSI and
SGJ in the LIFR ceilings at this time, but there may be a period
of low stratus at these terminals after 12Z through around 15Z.
VFR conditions should then prevail at the regional terminals by
16Z. Southerly surface winds sustained around 5 knots this
evening will become calm towards midnight, followed by
southwesterly surface winds of 5-10 knots beginning around 15Z.
The Atlantic sea breeze boundary will then develop at the Atlantic
coast, crossing the coastal terminals by 18Z and then the Duval
County terminals by 21Z. Surface winds will shift to east-
southeasterly around 10 knots following the passage of this
boundary.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 63 77 61 71 56 / 30 30 50 60 10
SSI 65 77 64 70 61 / 10 30 40 50 10
JAX 62 80 63 73 61 / 10 30 40 60 10
SGJ 65 81 65 74 64 / 0 20 20 40 20
GNV 61 82 63 76 60 / 10 20 20 50 10
OCF 62 83 62 78 63 / 0 20 10 30 10
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1055 PM EST Thu Nov 26 2020
.UPDATE...
Issued at 1055 PM EST THU NOV 26 2020
The stratus deck has been building south some over the past
several hours now. It does appear that portions of the Cumberland
Valley and far southeast could remain mostly clear through the
night. Therefore, you can see some fog in the river valleys and
this is well placed in the grids. Hourly temperatures have been
complicated since this stratus has been tougher to predict where
it will develop or track. The Cumberland Valley and east have seen
shaper temperature drops and adjusted for this in the hourly grids,
but will likely have to be refined given the complicated cloud
cover forecast. Also updated the sky grids to once again match the
latest trends and favored the HRRR in terms of guidance.
UPDATE Issued at 658 PM EST THU NOV 26 2020
We are seeing a deck of stratus this evening mainly north of the
Mountain Parkway and it has been pulling back northwest. However,
another wave will ride east and pull the stratus back across the
remainder of the area later tonight. The valleys have seen a
little quicker drop offs in the east and across the Cumberland
Valley and adjusted the temperatures to better capture this.
Otherwise main adjustments were to the sky grids to better reflect
the current obs and trends.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 345 PM EST THU NOV 26 2020
As of mid afternoon, an upper level ridge was centered in the
vicinity of the Bahamas, an upper level low was moving through the
northeast Conus, while an upper level trough extended from the
Hudson Bay region to the southwest Conus. This pattern leaves the
lower OH Valley in generally southwest flow aloft between he
ridge to the southeast and the trough to the northwest and west. A
weak shortwave moving through the OH Valley is moving east of
East KY at this time, while a more substantial shortwave was
upstream over the southern Plains and an upper level low was
currently over the southwest Conus but should not affect the
weather in the OH Valley until the end of the weekend. At the
surface, a ridge of high pressure extended from TN Valley into the
OH Valley, while a cold front was upstream of the area extending
from the Hudson Bay area to the Plains. Meanwhile, clearing has
worked into the southeastern half of the region and continues to
work to the northwest.
This evening and tonight, low level moisture trapped below a
subsidence inversion as weak mid level ridging builds across the
area is expected to persist in the 925 mb to 850 mb layer tonight
and into the day on Friday, despite sfc high pressure building
into the area. This low level moisture is finally expected to thin
as Friday progresses as the upstream cold front and associated
shortwave trough begin to approach from the west and northwest.
However, mid level moisture will arrive within a few hours of the
low level moisture thinning with the cold front moving across the
area from late Friday into Friday night preceding a mid level
trough.
As for sensible weather in the near term, plenty of clouds should
be experienced across much of the area during the entire near
term period. Clearing of low clouds should continue moving a bit
further northwest this evening, but guidance suggests this
stratocu and stratus should spread back to the southeast later
this evening and overnight. Some of the south or southwestern
sections may remain clear for several hours and with light winds
some valley fog may develop there in locations such as the
Cumberland River valley. The low clouds, however, should finally
thin out on Friday morning to Friday afternoon, before clouds
arrive ahead of the front and mid level arrive.
Temperatures during the near term period are expected to average
above normal for both highs on Friday as well as lows tonight and
Friday night with cloud cover anticipated.
.LONG TERM...(Saturday through Thursday)
Issued at 356 PM EST THU NOV 26 2020
The beginning of the extended consists of a fairly benign forecast.
We start by seeing heights rise with the exit of an upper level
trough, while sitting on the backside of its associated surface
front. High pressure builds in from the west behind this front
through the day, keeping things dry as skies begin to clear.
Temperatures take a dip for Saturday, but it`s not overly
significant.
Moving into the beginning of the workweek is where more of the
impactful weather takes place. Guidance has come to more of an
agreement over this system`s progression. A closed upper level low
over the southwestern US moves east over the weekend, before
gradually phasing with a trough moving through the northern stream.
This supports the formation of a surface low along the western Gulf
coast on Sunday. This low moves northeast through the Tennessee
Valley and up the Appalachians on Monday, strengthening significantly
as it does so. Eventually this low stalls above the Ohio Valley near
the Great Lakes Tuesday. In terms of sensible impacts, this system
starts by bringing us rain late Sunday through the first part of
Monday. However, temperatures take a drop as cold air moves in,
allowing for a transition to snow Monday night. Snow continues
through Tuesday as moisture wraps around the system, potentially
impacting evening and morning commutes. Confidence is growing for
this to be the first accumulating snow of the season, however, it is
still too early to nail down any specific accumulation amounts.
Transitioning into the latter half of the workweek, PoPs are on the
decrease as the low pressure system begins to weaken, filling in as
it moves away to the northeast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 639 PM EST THU NOV 26 2020
The latest trends in the satellite data and obs shows the primary
area of stratus pushing back north and west this evening. This is
allowing for most sites to clear outside of JKL/SYM who remain in
MVFR to start the period. There is a weaker shortwave aloft that
should pull this deck back east later tonight and this will affect
all the TAF sites once again bringing MVFR CIGs. The clearing
through the evening could allow for a little fog to develop in the
Cumberland Valley later tonight and this could affect SME/LOZ,
but this will be dependent on the progression the stratus deck
through the night. Finally by morning we will see improvements to
any VIS restrictions, and a return to VFR across the board by
Friday afternoon. The winds will remain light and variable through
the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...DJ
SHORT TERM...JP
LONG TERM...HAS
AVIATION...DJ
Area Forecast Discussion
National Weather Service Pueblo CO
310 PM MST Thu Nov 26 2020
.SHORT TERM...(This evening through Friday)
Issued at 247 PM MST Thu Nov 26 2020
Current water vapor imagery and upper air analysis is indicating
moderate southwesterly flow aloft across the region, as a broad
upper trough is shearing apart across the Intermountain West at this
time. Water vapor imagery is indicating the main portion of the
trough translating across the Northern Rockies with shear axis into
northwestern Colorado at this time, as secondary energy digging down
the backside of the system is developing a mid level circulation
across the southern Great Basin at this time. IR satellite and
regional radars indicating cloud top cooling with scattered echoes
along the shear axis stretching from east central Utah, through
northwestern Colorado and into northeastern Wyoming, with mainly
clear skies across southeast Colorado at this time.
Latest models remain in good agreement of the main trough continuing
to translate east into the Upper Midwest tonight, as secondary
energy cuts off an upper low across southern Arizona by 12Z Friday.
This will allow for weak uvv to slowly shift south and east across
the central Rockies through the evening as the shear axis dissipates
through the overnight hours. Models indicating the best lift and
moisture to remain across the northern and central mountains through
the late afternoon and evening, with the HRRR the most aggressive at
spreading light qpf south across the Pikes Peak region and into the
southeast mountains after midnight, as north to northeast upslope
flow develops behind the passing system`s weak cold front. At any
rate, current forecast keeps isolated to scattered pops across
central mtns tonight, with isolated pops spreading south and west
across the higher terrain through the evening into early Friday
morning. Lack of available moisture remains a limiting factor for
snowfall, with accumulations of a few inches possible across the
higher terrain of the ContDvd, and mainly flurries if anything over
and near the eastern mts.
For tomorrow, the southern Arizona upper low is forecast to start to
lift out across the southern Rockies, with some differences in the
track, though most keep it too far south to bring widespread
precipitation to the area. Best chances of generally light snowfall
will be across the eastern San Juan mountains Friday morning, with
pops spreading east into the southern Sangre de Cristo mountains
through the day as southerly flow aloft becomes more east to
southeast Friday afternoon. Otherwise, dry conditions are expected
across the area with temperatures near to slightly cooler than
today`s readings.
.LONG TERM...(Friday night through Thursday)
Issued at 247 PM MST Thu Nov 26 2020
Better agreement among the models through Monday before large
discrepancies arise for next week. Ensemble spreads continue to be
large, and operational solutions all over the place with little
run to run consistency. This continue to lead to very low forecast
confidence for next week.
Friday night and Saturday...a slow moving upper level low will be
tracking eastward across the Desert Southwest into the Texas
Panhandle. The GFS and ECMWF remain in agreement with the storm
track, while the NAM continues to be the northerly outlier.
Expecting light snow over the San Juan Mountains and southern
Sangre de Cristo range Friday night into Saturday morning. Not
anticipating much in the way of accumulations, with 1 to 3 inches
possible through Saturday morning. Continued with low pops along
the New Mexico border for Saturday morning based on the NAM, but
wouldn`t be surprised if everything remains to the south of the
Plains. If precipitation does fall on the Plains along the New
Mexico border, it will be in the form of rainfall, as afternoon
high temperatures are expected to be in the 50s.
Saturday night into Monday...a secondary trough will pass into the
northern Plains Saturday night sending a cold front south across
the Plains. This will bring about a 10 degree cool down for
Sunday. This frontal boundary will come through dry, with the main
issue being gusty north winds across the Plains throughout Sunday.
Expected continued dry conditions to continue on Monday under
broad northwesterly flow aloft. Temperatures will rebound back
into the 50s across the region.
Tuesday through Thursday...very low confidence in the forecast
evolution during this period. The GFS pattern evolution seems a
bit far fetched, developing an upper low over Colorado and
wobbling it around the Intermountain West through the end of the
week. The ECMWF is a bit more feasible, dropping an upper level
low out of the Northern Rockies, but then has no idea where it
wants to take it. The ECMWF would bring chances for rain and snow
to the area Tuesday into Wednesday. But given the uncertainty and
large ensemble spreads, confidence in any solution is very low at
this point. For now, just have low chances for precipitation over
the Mountains through the middle of next week, which will likely
need to be either raised or removed if we can gain any run to run
model consistency. Mozley
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 247 PM MST Thu Nov 26 2020
VFR conditions expected at COS, PUB and ALS over the next 24 hours,
as an upper level disturbance translates across the Rockies. This
system will bring increasing clouds to the area tonight. Isolated to
scattered snow showers are expected across the northern and central
mts this afternoon and evening, with a few showers possibly moving
into the Pikes Peak region later this evening.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MW
LONG TERM...MOZLEY
AVIATION...MW
Area Forecast Discussion
National Weather Service Tulsa OK
915 PM CST Thu Nov 26 2020
.DISCUSSION...
Weak cold front has pushed into wrn Osage/Pawnee/Creek Counties at
this time, and will continue to move through much of our CWA
overnight. Increasing low level moisture/isentropic upglide will
result in low clouds overspreading southeastern Oklahoma and west
central Arkansas tonight. Latest HRRR and RAP as well as 00z NAM
suggest some light rain is possible in that area overnight, as
isentropic upglide in 290k through 300k surfaces increases with
condensation pressure deficits decreasing to only 10mb. In addition,
seven of twenty 18z GEFS members produce measurable precip sern OK
tonight. Will introduce slight chance pops/light qpf 06-12z, with
lift expected to shift south and east of our CWA after 12z. Remainder
of forecast elements trending well. Happy Thanksgiving y`all!
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...69