Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/25/21
Area Forecast Discussion
National Weather Service Lincoln IL
907 PM CST Wed Feb 24 2021
.SYNOPSIS...
Issued at 906 PM CST Wed Feb 24 2021
Expect partly cloudy skies overnight, with northwest winds at 5 to
10 mph. The rest of the work week will be dry, with temps near
normal on Thursday before climbing above average for the weekend.
A few light precipitation chances return this weekend, but there
will be plenty of dry time.
&&
.UPDATE...
Issued at 906 PM CST Wed Feb 24 2021
A band of clouds was moving south through central Illinois this
afternoon into evening. It`s forward progress has slowed a bit as
the back edge reached just south of the I-72 corridor. HRRR and
RAP guidance show the clouds should continue slow movement
southward overnight. However, sporadic redevelopment of low
clouds could occur later tonight, especially farther north, mainly
north of Peoria. Have gone with more clearing in the sky forecast,
and subsequently have lowered the low temps slightly. We still
have some snow cover north of Galesburg to Lacon, so that area
could see lows dip toward the teens. The remainder of our forecast
area should generally bottom out in the 20s for lows.
The pressure gradient and pressure rises have weakened as the cold
front from this morning advances farther away to the southeast. NW
winds will sustain in the 5 to 10 mph range the rest of the night.
Our counties NW of the IL river could see winds become light and
variable as the surface ridge axis approaches that area, which
would also support the colder low temps.
&&
.SHORT TERM...(This evening through Thursday)
ISSUED AT 323 PM CST Wed Feb 24 2021
A low pressure system moved from the Great Lakes to the northeast
today, and its associated cold front exited Illinois earlier this
afternoon. In its wake, breezy northwest winds will gradually
taper off, becoming light overnight. This evening, an area of low
clouds are set to move northwest to southeast across the area.
The best chance for clearing overnight will be northwest of the
Illinois River valley, where lows are expected to be in the low
20s. Elsewhere, lows will be in the mid to upper 20s. A dry,
pleasant day is on tap tomorrow, with near normal temps and
lighter winds as high pressure builds.
.LONG TERM...(Thursday night through Wednesday)
ISSUED AT 323 PM CST Wed Feb 24 2021
Over the next week, an active pattern develops, with multiple
waves expected to move across the country. However, central IL
looks to remain relatively dry compared to the upper Midwest or
the Tennessee Valley. Areas north of I-74 and south of I-70 stand
the best chance of seeing precip from these systems.
The first wave is progged to move through the southern branch of
the jet stream during the day on Friday. The precip associated
with this wave is expected to remain well south of central IL. A
better chance for precip across all of central IL comes Friday
night into Saturday as an upper trough lifts from the central
Plains into the Great Lakes. The precip will primarily be rain but
a few snowflakes may mix in at times in locations north of I-74.
Later in the weekend, a boundary stalls across the Tennessee
Valley resulting in prolonged precipitation chances south of I-70.
A sharp gradient in precip amounts appears likely, with the
heaviest amounts south of the ILX CWA. The current expectation is
for around 0.25 inches of QPF in ILX counties south of I-70, which
would be light enough to limit any additional river flooding
concerns.
Temps will be above normal through the weekend, with the warmest
temps expected on Saturday as clear skies and southwesterly winds
result in highs climbing into the mid to upper 50s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 556 PM CST Wed Feb 24 2021
A band of MVFR clouds will pass across the terminal sites during
the first 2-4 hrs of the 00z TAF period. High pressure building in
the rest of the night should provide VFR conditions, but a brief
period of MVFR clouds and fog could develop just north of PIA late
tonight. Have included that trend in this set of TAFs for planning
purposes, but confidence is low to medium that those conditions
will affect the PIA airport directly. The gusty northwest winds
will continue to subside this evening, but sustained 10KT levels
could linger through 03-04z. Once winds diminish to 06-07KT, wind
speeds are expected to remain less than 10kt for the remainder of
the 00z TAF period.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SYNOPSIS...Deubelbeiss/Erwin
SHORT TERM...Deubelbeiss/Erwin
LONG TERM...Deubelbeiss/Erwin
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Marquette MI
756 PM EST Wed Feb 24 2021
.SHORT TERM...(This evening through Thursday)
Issued at 351 PM EST WED FEB 24 2021
WV imagery and RAP analysis indicated mid/upper troughing from
Hudson Bay into the north Central CONUS. The shortwave and sfc low
that brought snow through Upper Michigan early today has departed
toward Quebec leaving clearing skies as drier air moves in on nnw
winds. An upstream shrtwv into southern Manitoba and its weak sfc
reflection supported sct -shsn into eastern ND and northwest MN.
Tonight and Thursday, expect a period of mostly clear skies this
evening that will give way to increasing clouds overnight as the
Manitoba shrtwv approaches the area. Favorable radiational cooling
before the clouds arrive will allow temps to drop into the single
digits inland with teens near the Great Lakes. Sct -shsn will move
into the west late tonight. Ice cover on Lake Superior will be
patchy enough so that 850 mb temps to around -13C along with
convergent westerly winds will aid the snow showers. Given the
marginal instability and forcing from the shrtwv, Any snowfall
amounts should remain light, generally less than an inch. Diurnal
heating may also boost the -shsn as the shrtwv moves through the
central and east into the afternoon. Highs should climb to around 30
north and the low to mid 30s south.
.LONG TERM...(Thursday night through Wednesday)
Issued at 339 PM EST WED FEB 24 2021
The long-term period looks active with a lot of back-and-forth in
temperatures and multiple snow chances, but at the moment, no
significant storms.
Thursday night will be seasonably cool with ridging overhead
initially. However, as the night goes on, SW winds will increase as
a trough approaches from the NW. Despite skies partly cloudy or even
mostly clear, these increasing winds should help keep the PBL mixed
to keep temps in the teens for lows rather than in the single digits.
This stronger wind will continue into Friday as a 40-50 kt LLJ
overspreads the U.P. from west to east. There should initially be
enough sunshine Friday morning to help mix down some higher gusts
around 25-35 mph from the SW. Cloud cover will increase in the
afternoon leading to decreased mixing, but this lack of mixing will
be compensated by winds aloft increasing and reaching their peak in
the evening thus maintaining SW 25-35 mph gusts through the day and
into the evening. The early-day sunshine and downslope wind should
allow temps to climb above most raw guidance into the upper 30s and
low 40s for highs.
Two weak disturbances will move through the area this weekend, one
late Friday night into Saturday morning and the other Sunday
morning. They are expected to take similar tracks. Both will be
quick movers, and neither will have significant moisture to work
with. The Friday night snowfall will mainly affect areas east of a
line from Iron Mountain to Marquette. The snow from the Sunday wave
looks to be displaced a little bit to the east of that. Neither wave
should cause accumulations of more than an inch, and most of what
falls Friday night will melt on Saturday with highs getting into the
upper 30s and low 40s. Things begin to turn colder on Sunday with
the first in a series of two cold fronts.
The second cold front will likely move through late Sunday night or
early Monday morning. However, there remains some uncertainty in
just how cold the air will be behind it. The 06z GFS 850 mb temp of
around -27 C was near the bottom of the distribution of the GEFS
around 12z-18z Monday, and the 12z run is similarly cold.
Deterministic EC and UKMET from 00z are warmer (around -15 C and -23
C, respectively). WPC cluster analysis shows a signal for
underdispersion of the ensemble systems, especially in regard to the
speed/placement of the mid-level short wave that is responsible for
ushering in the brief cold shot. While 80% of 00z GEFS members fall
into two clusters with a deeper trough, 76% of the EC Ens members
fall into the other two clusters with a much flatter upper-level
pattern. Even the warmer members should still support some lake-
effect snow in the NW wind snow belts Monday afternoon, albeit
briefly.
Regardless of how cold and/or snowy Monday ends up being, models
show an amplifying ridge and WAA Monday night followed by strong SW
flow on the western edge of the ridge Tuesday. Raw models get temps
into the mid 30s for highs on Tuesday but if not much snow
accumulates the day before, the gusty SW flow and some sunshine with
the March sun angle could easily drive temps even higher. With a
pretty good ensemble consensus for 850 mb temps around -2 to -3 C,
some sunshine, and a stiff SW wind, it seems very unlikely that
highs will stay below freezing as suggested by the NBM
deterministic. For now, went with the NBM 75th percentile for high
temps, which is about 6-8 F warmer than the NBM deterministic. This
puts temps mostly in the upper 30s, with some low 40s west half.
Wouldn`t be shocked if some places get into the mid 40s though.
The warmth looks to continue into the end of next week. The CIPS
Analogs for the GEFS for the period next Thursday to next Sunday
show ~75% of matching analogs with above-normal temps and median
highs in the low 40s (and even 30-40% chances are highs in the 50s
near the Wisconsin line).
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 606 PM EST WED FEB 24 2021
VFR conditions will briefly lower back down to MVFR later tonight
and Thursday morning as a shortwave and associated weak sfc
trough move through the area. Onshore westerly flow could even
result in some light lake effect snow into KIWD and KCMX. KSAW
will see an increase in clouds toward 12Z and could see a brief
period of MVFR cigs, but westerly downsloping flow there should
limit the period of MVFR conditions to a few hours. Expect
general improving conditions to VFR Thursday afternoon as ridging
builds in from the west low-level flow backs to the southwest.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 351 PM EST WED FEB 24 2021
Northwest winds of 25 to 30 knots over the east will diminish
quickly this evening and back westerly tonight. Southerly winds
increase with 35 knot gales over the east possible Friday. Winds
then dies down to 25 knots out of the northwest on Saturday.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Watch from Friday afternoon through Friday evening for
LSZ249>251-266-267.
Lake Michigan... None.
&&
$$
SHORT TERM...JLB
LONG TERM...RJC
AVIATION...Voss
MARINE...JLB
Area Forecast Discussion
National Weather Service New York NY
1016 PM EST Wed Feb 24 2021
.SYNOPSIS...
High pressure gives way to a cold front that moves through the
area overnight. High pressure then returns, building in from
the west Thursday into early Friday. The high over the region
early Friday moves off the coast as a frontal system approaches.
The frontal system impacts the area Friday night and Saturday.
Another frontal system moves through the region Sunday into
Monday. High pressure briefly returns Tuesday. Another frontal
system may impact the area Wednesday.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Forecast has been updated to reflect the latest obs. The main
adjustment was for a slightly faster decrease in clouds,
especially further west later in the overnight.
A deepening low traveling from the Eastern Great Lakes will be
moving across Northern New England overnight and eventually
into the Canadian Maritimes by early Thursday. This low will
have its associated cold front at the surface move across the
local region overnight. The front and mid and upper level trough
will have a lack of moisture as there will be mostly westerly
flow and highest positive vorticity advection will be displaced
well north of the local region. The HRRR conveys some
reflectivity echoes crossing the region for the first half of
the night. POPs in the forecast are no greater than 30 percent
for any light rain showers tonight.
Precipitation type in this case is just rain showers as ambient
temperatures will be mainly in the 40s during the frontal
passage. Some locations may very well stay dry with the lack of
moisture in the trough and cold front. Despite the southerly
flow earlier, there will remain enough dry air in the sub cloud
layer to preclude much in the way of any meaningful shower
activity from making it down to the ground. Lows will be in the
lower to upper 30s using a blend of model data with an emphasis
on MOS consensus. These temperatures will be reached by early
Thursday morning. The temperature range will not be as vast as
radiational cooling will be somewhat mitigated with gusty winds
in the boundary layer with wind direction becoming more west to
northwest late tonight.
Clouds decrease late tonight into Thursday as a ridge of high
pressure builds in at the surface.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
For Thursday and Thursday night, high pressure builds in from
the west at the surface and aloft, there will be zonal flow.
Thursday will still have a steep pressure gradient and while
cold air advection will result in a colder day relatively
compared to the previous day, high temperatures forecast are
still expected to be above normal. Boundary layer vertical
mixing adiabatically up to around 875mb is expected, relatively
deeper than the previous day. With this gusty NW flow, coastal
locations are expected to be warmer with downslope flow. Highs
for much of the region will be from the low to upper 40s with
those upper 40s temperatures for NYC Metro and Long Island. Wind
gusts will reach near 25 to 30 mph with a few locally higher
gusts possible up to around 35 mph at times.
Winds will decrease Thursday night with a weakening of the
pressure gradient. Gusts will diminish late. This will be as
the center of the high pressure area gets closer to the local
area. The decrease in winds with still mostly clear sky
conditions will allow for more optimal radiational cooling. This
will present a more vast range of lows, from the upper teens to
lower 30s.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
A mainly zonal upper flow remains across the country through
the extended period with the northern stream dominating as a
series of shortwaves moves across the northeast Friday night
into Saturday, with another Sunday into Monday, and possibly yet
another wave Wednesday. Models have been more consistent with
the timing of the low impacting the area Friday night into
Saturday, and with more certainty have increased probabilities
to likely during Saturday. Thermal profiles Friday night as
showing the precipitation beginning as light snow and then
quickly warming as warm advection increases through the day
Saturday. During the morning into early afternoon the
precipitation transitions from snow to all rain. There is little
cold air expected to move into the region behind the low
Saturday night as weak ridging briefly builds into the
northeast. Then yet another shortwave and low track to the north
of the area Sunday into Monday. With the warm air remaining
across the region this system will be all liquid.
After this system model guidance becomes uncertain with the
potential for another weak system to move through Wednesday. The
GFS keeps near zonal flow and surface high pressure to the
south while the ECMWF and Canadian develop the low in the
southern stream and moves this system into the region. There is
also uncertainty with any phasing with the northern stream. With
the uncertainty will only have slight chance probabilities at
this time.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
A cold front passes overnight. The front should move through the
city terminals in the 6-7z time frame.
VFR through the TAF period, with only a few sprinkles possible with
the frontal passage overnight. Confidence of sprinkles / showers is
too low to include in TAFs. Any LLWS should subside towards 6z.
Wind gusts should resume again overnight behind the frontal
passage and a wind shift to the NW at 5-9z. NW winds with gusts
in the 20-25kt range are expected on Thu.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Low confidence especially with regard to timing with gusts
shutting off, and then starting up again overnight into early
Thursday morning with amendments possible.
.OUTLOOK FOR 0Z FRIDAY THROUGH MONDAY...
.Thursday night...VFR. WNW winds diminish.
.Friday...VFR.
.Saturday...MVFR or lower with rain. A wintry mix possible at the
onset.
.Sunday...Chance of rain and MVFR.
.Monday...Strong NW winds possible behind a cold front.
Detailed information, including hourly TAF wind component forecasts,
can be found at: http:/www.weather.gov/zny/n90
&&
.MARINE...
No changes made to winds or seas at this time.
Small craft advisories are in effect for all waters through
Thursday morning. Then, for Thursday afternoon, small craft
advisories remain for Eastern Long Island Sound, Peconic and
Gardiners Bays as well as the ocean zones. For Thursday evening,
the small craft advisory continues for the ocean east of Fire
Island Inlet. All waters are below SCA conditions for late
Thursday night.
Southwest winds have increased across the waters with the
development of some gusts to near 25 kt. Ocean seas are 4 to 5
ft east of Moriches Inlet and more in the 3 to 4 ft range to the
west of Moriches Inlet. Wind gusts expected to increase to near
25 kt mid to late this afternoon and for all waters tonight with
ocean seas building to 5 to 7 ft.
Widespread gusts in the 25-30 kt range are expected tonight into
Thursday morning. On the ocean waters, some gusts closer to 35
kt will be possible tonight, but just occasional in frequency.
There will be a significant inversion that will really limit the
high gusts and mixing down of gale force winds. The 25kt gusts
will likely linger across the eastern waters and ocean waters
for Thursday afternoon. Ocean seas stay elevated in a 5 to 7 ft
range tonight through Thursday afternoon.
Conditions for both winds and seas lower Thursday night allowing
for eventual return to sub-SCA conditions gradually for the
forecast waters.
Winds and seas will be below SCA conditions Friday with high
pressure over the waters. As a frontal system impacts the waters
Saturday winds and seas on the ocean waters will increase to
SCA levels. Winds diminish late Saturday night into Sunday as
high pressure builds back into the waters, however, ocean seas
will remain elevated into Sunday night. Small craft conditions
return once again on the ocean waters Monday and remain into
Monday night as yet another frontal system impacts the waters.
The non ocean waters are expected to remain below SCA levels
Friday through late Monday. With a gusty northwest flow
developing behind the departing low as strong high pressure
builds SCA conditions will be possible as all the forecast
waters Monday night.
&&
.HYDROLOGY...
Showers through tonight will amount to less than a tenth of an
inch. No hydrologic impacts are anticipated through Wednesday.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until noon EST Thursday for ANZ335-338-
345.
Small Craft Advisory until 6 PM EST Thursday for ANZ330-340-
355.
Small Craft Advisory until 9 PM EST Thursday for ANZ353.
Small Craft Advisory until 11 PM EST Thursday for ANZ350.
&&
$$
SYNOPSIS...JM/MET
NEAR TERM...JM/MET
SHORT TERM...JM
LONG TERM...MET
AVIATION...JE
MARINE...JM/MET
HYDROLOGY...JM/MET
Area Forecast Discussion
National Weather Service Pueblo CO
846 PM MST Wed Feb 24 2021
.UPDATE...
Issued at 843 PM MST Wed Feb 24 2021
Have updated forecast to bump up snow amounts 1-2" mainly across
El Paso county. Some areas have received 2-3" of snow and snow is
still coming down at a pretty good rate across the county. HRRR
still shows the heaviest is yet to come during the predawn hours
Thursday morning. Pueblo should get into the act around 1 AM.
/Hodanish
&&
.SHORT TERM...(This evening through Thursday)
Issued at 241 PM MST Wed Feb 24 2021
An upper level trof will be moving toward the area from the
northwest overnight, with its axis expected to lie from over
southern wy to northwest AZ by 12Z Thu. The HRRR and RAP are slow to
develop precip over the area, with only some isolated evening
showers over El Paso and Teller Counties, but not really showing
high chances for snow over the Palmer Divide and northern Teller
County until around midnight, along with scattered or likely chances
over portions of Lake County. The RAP and HRRR then spread the snow
south through Teller and El Paso Counties, and into Fremont County
and the Wet mtns, and more into the central mtns as well. Up
through 10Z, these models keep the rest of the forecast area dry.
Then by 12Z the snow is expected to spread all along the eastern
mtns and I-25 corridor. The GFS is fairly similar to the RAP and
HRRR, although it shows some evening showers over the eastern mtns
and portions of the plains, with little QPF. The NAM is rather dry
as well through 06Z, but does have some showers over the eastern
mtns and the Palmer Divide. The NAM also shows the bulk of the
precip after midnight, and especially toward morning, and also
include areas north of Highway 50 over the southeast plains. The NAM
continue to show higher chances and accumulations of precip than the
other models, over portions of the San Luis Valley and southwest
mtns.
On Thu, the upper trof slowly moves southeastward over CO, with the
mtns and portions of the I-25 corridor still being the areas with
the highest snow chances, and mainly through noon. The forecast
models have backed off on precip amounts for portions of the
southern I-25 corridor, south of Walsenburg. Thu afternoon the
precip should decrease over most locations, but the southern mtns
will probably have fairly high chance of light snow through the
afternoon.
There are still uncertainties as to how much snow may fall,
especially in the San Luis Valley and southwest mtns, and over
portions of the southeast plains, mainly Crowley and Kiowa Counties.
However, confidence is probably the highest over Teller and El
Paso Counties.
Will leave the current Winter Weather Advisory as is for now. Even
if snowfall amounts in some of the advisory area end up not being
all that much, there could be enough snow to make driving a little
challenging through midday Thu.
.LONG TERM...(Thursday night through Wednesday)
Issued at 241 PM MST Wed Feb 24 2021
The next system to pass over the area will be a weak trough slated
to move over Colorado during the day on Friday. Models have been
trending warmer for the high temperatures, so adjusting along with
guidance bumped up high temps a few degrees across the board,
leaving high 40s to low 50s over the plains and 30s-40s over the
higher terrain. As the trough swings down Friday afternoon,
stability and moisture should be good enough to trigger some brief
snow over the Continental Divide, but any accumulations are expected
to be very light, and even then snow amounts in general have been
trending down the last 24 hours in the model guidance. Winds are
also expected to pick up later in the day over the mountains, but
gusts should still stay below the 50 mph mark.
Snow over the Continental Divide will likely continue into Saturday
after a seasonably cool evening. As the next upper trough makes its
way over Colorado. Along with this system, a cold front is expected
to make its way south across the plains during the late afternoon,
and while it will bring in some brief gusty winds and bring
temperatures down Saturday night and Sunday, any snow associated
with this front will likely stay confined to the Continental Divide.
Current runs of the GFS and EC both show a closed low being sent far
south of our area Sunday night into Monday, which could put a little
snow on the south part of the area near the Raton Mesa. Confidence
in the models that far out is low when considering snow chances and
amounts, but the synoptic set up is possible. After Monday, the
models diverge more, but an upper ridge is expected to build in
Tuesday and give us a brief dry and warm period through the first
half of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 324 PM MST Wed Feb 24 2021
Updated for spelling errors and updates to timing on snowfall.
KALS...VFR conditions are expected throughout the day today along
with gusty southwest winds up to 35 mph. Starting around 05Z snow
will be in the vicinity of the terminal which may lower cigs
depending on how close they get. Models have been inconsistent
today on the exact coverage of the snow, but confidence iS
moderately high that snow could begin falling close to KALS around
10Z, limiting vis and cigs to potential IFR-LIFR conditions for a
few hours. The snow is expected to decrease in coverage tomorrow
afternoon, but will likely linger around the TAF site through the
end of the forecast period.
KCOS...Low-mid level clouds and gusty winds have persisted at KCOS
this afternoon, although the gusts have decreased over the last few
hours. The low clouds are expected to persist through the rest of
the night as snow is expected to set in within the next few hours.
While the intensity and the extent of the snow has been inconsistent
in the models today, there is moderately high confidence that the
snow will set in near the TAF site by 01-02Z and last into
tomorrow morning, resulting in IFR-LIFR conditions prevailing for
several hours at a time. Will continue to monitor trends. After
the snow dissipates tomorrow VFR conditions are expected to
return.
KPUB...Gusty east winds and low clouds continue over the TAF site
and will likely persist through the forecast period. Snow is
expected to develop over the area by about 04Z, and could move
over the TAF site as early as 04Z, although it is notable that
models have been inconsistent today on the extent of the snowfall.
Based on recent guidance, there is moderately high confidence
that the snow will last over the terminal until around 17Z
tomorrow, generally light but becoming locally heavy at times,
which will keep things in the IFR-LIFR range through tonight. Once
the snow dissipates tomorrow MVFR-VFR conditions will return for
the rest of the forecast period.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 5 AM to 1 PM MST Thursday for
COZ074-075-087-088.
Winter Weather Advisory from 1 AM to 11 AM MST Thursday for
COZ072-073-076>080-083-085-086.
Winter Weather Advisory until 11 AM MST Thursday for COZ081-082-
084.
&&
$$
UPDATE...HODANISH
SHORT TERM...28
LONG TERM...GARBEROGLIO
AVIATION...GARBEROGLIO
Area Forecast Discussion
National Weather Service Blacksburg VA
704 PM EST Wed Feb 24 2021
.SYNOPSIS...
A weak cold front will cross the area from the northwest
tonight with a chance of showers across the mountains. High
pressure will return for Thursday before widespread
precipitation arrives for Friday and into the weekend.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 704 PM EST Wednesday...
...Light Mountain showers possible tonight as a cold front
moves through...
A cold front to our west across the Ohio Valley will drop
southeast tonight into Thursday. The regional radars showed
scattered showers along the frontal boundary. The HiResW-ARW-
East, HRRR and NAM indicated showers will weaken as they hit the
western mountains and dry air. This evening 00z RNK sounding
highlighted the dry air with a PWAT around 0.23 and a west flow.
Made some minor adjustments to temperatures for this evening
into tonight utilizing the latest surface obs, their trends and
blended in the NBM. Made some minor adjustments to pops and
weather allowing for a few showers to work into the west. More
changes later tonight.
As of 110 PM EST Wednesday...
Forecast remaining on track so far this afternoon thanks to the
decision to go above most guidance for temperatures this
afternoon, as temps east of the Blue Ridge are already in the
low to mid 60s. No changes for the forecast since this AM.
Previous Discussion...
As of 1135 AM EST Wednesday...
Warm Afternoon Ahead: Light Mountain Showers Tonight With
Front...
Temperatures continue to quickly warm this morning with high
pressure settled over the Mid-Atlantic today. No changes made to
the forecast temperatures today, which should top off 15 to 20
degrees above normal. Ironically though, still not close to
record breaking thanks to a notable spike in temperatures in
1943.
A SW wind should pick up through the afternoon ahead of a front
that is currently pushing along the Ohio Valley and Mid-South.
While this return flow should help ushering a slightly more
saturated airmass, overall return flow looks rather weak thanks
to the dry airmass in place it needs to overcome over the
southeastern states.
Arrival time for the front remains pretty similar to the
previous forecast, with earliest arrival being roughly 10PM. Any
appreciable accumulation remains confined to the far western
slopes, while more so just some traceable precipitation is
expected further west to the Blue Ridge. Dry air that will
remain in place combined with downslope drying should keep
things dry through the event for areas east of the Blue Ridge:
just an increase in clouds for the overnight. Temperatures
through the night will remain above freezing, besides for the
far western slopes where temperatures will drop below freezing:
it`s here that we could see some of the light showers transition
to light snow showers with accumulations not worth batting an
eye at. Shower chances drop off as quickly as they arrived by
sunrise Thursday AM.
For Thursday, low level clouds in the west will gradually mix
out while clouds in the east will already be decreasing when
most wake. Behind the front comes cooler weather for the region,
bringing us back to near normal for highs Thursday. However, we
aren`t completely down with the front because it stalls out to
our south Thursday, and will gradually start to slip back
northward, increasing our upper level clouds through the
afternoon and evening.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 243 PM EST Thursday...
An active end to the workweek as multiple storm systems parade
our way...
Cloud cover will continue increase over the area Thursday night with
high pressure sliding off the coastal Delmarva and our front
remaining stalled along the southern Appalachians. This front will
be the trigger point for pieces of shortwave energy coming in from
the Midsouth/Southern Plains region Friday and Saturday.
Meanwhile our aforementioned area of high pressure above will leave
a cold wedge of air in place for a brief shot of wintry
precipitation especially at higher elevations Friday night into
Saturday. Earlier model runs bring precipitation in earlier
Friday but with the high slow to move east most of the model
guidance is a bit slower due to residual dry air in place. As of now
precip looks to move from south to north late Friday morning into
early Friday afternoon mostly in the form of rain. As for the chance
of wintry precipitation the NAM, Euro, GFS, and Canadian are all in
good agreement in regards to keeping the wedge firmly in place
Friday afternoon/evening with the bulk of our wintry precipitation
west of the Blue Ridge. Highest confidence for any light
accumulations look to be from the North Carolina mountains back into
the southwestern Virginia and West Virginia mainly west of the Blue
Ridge Saturday morning. Once again though this will hinge on
marginal surface temperatures and a more established warm nose
taking over aloft Friday night into Saturday midday.
The good news is that we look to dodge any sort of major winter
weather impacts this weekend as temperatures warm with a warm front
lifting north behind our exiting trough and out ahead of our next
cold front incoming from the west for the latter half of the
weekend. Overall it`s all about the need for the umbrella and rain
gear Friday and Saturday. Rain amounts will be on the order of a
half an inch to three quarters of an inch of rain ending by midday
Saturday. Some leftover showers will remain Saturday afternoon and
evening before our next wave of moisture moves in.
Our coldest day looks to be Friday with the wedge in place we can
expect highs close to 40 degrees west of the Blue Ridge with low to
mid 40s out east. By Saturday everyone warms back into the low to
mid 50s in the west to close to 60 degrees south of the US-58
stretch.
Confidence remains moderate in the short term based upon the
strength of the cold air wedge that looks to settle in and overall
placement of where the heaviest axis of precipitation will set up
late Friday into Saturday.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 243 PM EST Wednesday...
..The pipeline of moisture continues on into early next week...
Our overall pattern doesn`t really budge too much in the long term
period. High pressure remains firmly entrenched over the central
Gulf of Mexico and central Atlantic leaving us with continued
chances for rain due to waves of energy caught in between. Our next
shot of rain arrives Sunday as another front and resultant piece of
energy moves our way from the Mid-South and Ohio River Valley. This
should be the wettest day of the weekend with rain mostly throughout
the day continuing into the early part of the new workweek as the
front sinks through. Both the Euro and GFS allow the front to sink
south by Monday afternoon leaving us with mild temperatures as high
pressure to our north settles in. Highs on Sunday and Monday
especially out east will once again be back in the upper 50s and low
60s while areas west of the Blue Ridge remain slightly cooler.
Beyond Monday the models get a bit murky. The Euro wants to bring
another area of low pressure in with a resultant front from the Ohio
River Valley Tuesday into Wednesday while the GFS keeps us under the
control of high pressure. For now I decided to keep chance Pops in
place with temperatures returning back to seasonal levels for the
midweek stretch.
Confidence remains moderate in the long term period.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
As of 637 PM EST Wednesday...
VFR flight condition will prevail this evening into tonight.
Winds will diminish slightly this evening, but remain out of
the southwest ahead of a cold front that will move into the
region overnight. With limited moisture to work with over the
area, KBLF and maybe KLWB will be the only TAF sites that could
pick up some measurable precipitation overnight. Otherwise, only
a brief light shower is possible for all other sites.
SCT to BKN MVFR clouds are possible in the west especially
at KBLF and KLWB. Areas along and east of the BLue Ridge should
remain VFR through the period. Following the front moving
through, ceilings will remain impacted in the west while clouds
quickly mix out for the east. Behind the front, winds will
shift to the north to northwest Thursday. VFR conditions will
prevail Thursday afternoon into Thursday night.
Medium confidence in ceilings, visibilities and winds during
the taf period.
Extended Aviation Discussion...
Prolonged periods of sub VFR flight conditions are expected
Friday and through the weekend with a frontal boundary stalled
across the region. Numerous waves of low pressure will move
along the front, bringing numerous chances for precipitation.
Rain with Sub-VFR conditions are likely Monday with chance for
snow Monday night into Tuesday.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...PM/RR
NEAR TERM...KK/RR
SHORT TERM...ET/PM
LONG TERM...ET
AVIATION...KK/RR
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
705 PM EST Wed Feb 24 2021
.UPDATE...
Despite a relatively warm day, we saw dewpoints cooperate across
the northern half of the CWA as surface high pressure over the NE
Gulf has kept us slightly drier air courtesy of a light
northwest/north wind. Overnight PWAT values are expected to flirt
with 0.30 inches which suggests a very dry atmosphere will be in
place. Due to the dry airmass, clear skies, and calm winds
(especially across the Nature Coast), have opted to nudge low
temps several degrees cooler to align closer to MOS guidance as
all these things indicate a strong radiational cooling night.
Thinking low/mid 40s across much of the Nature Coast and low/mid
50s across the I-4 corridor.
RAP forecast soundings at KCTY and KINF shows a saturated and
decoupled boundary layer due to the aforementioned cooling. With
the added support from hi-res visibility models, went ahead and
included Areas of overnight fog for parts of the Nature Coast.
Much farther south, favorable conditions over Miami`s area may
bleed into some of our neighboring counties - so some patchy
wording was also introduced into these areas. However, certainty
here is much lower than the Nature Coast due to less low level
moisture.
&&
.AVIATION...
VFR conditions through the period with perhaps some FEW/SCT clouds
near 030 during late morning into early afternoon across northern
sites. Otherwise, the forecast consists mainly of subtle wind
shifts between NNE and NW. These winds will generally remain AOB 8
knots.
&&
.MARINE...
High pressure over the area will keep warm, dry, and otherwise
very pleasant boating conditions for the next several days.
Strengthening surface high over the Atlantic will lead to an
increase in southeasterly winds by the weekend. However, these
winds are still expected to remain just below cautionary
headline thresholds, so no hazards are anticipated into early
next week.
&&
.FIRE WEATHER...
High pressure over the northeast Gulf of Mexico is helping to
filter in some drier air into the area through tomorrow. Strong
daytime mixing will result in relative humidity levels dipping
below critical values during the afternoon, especially south of
I-4 and east of I-75. While ERCs will also be elevated across the
area, a lack of strong wind speeds will preclude the issuance of
Red Flag Warnings. Moisture increases beginning on Friday and
continuing into the weekend with no major fire weather concerns
expected.
&&
.Preliminary Point Temps/PoPs...
TPA 55 79 59 81 / 0 0 0 0
FMY 59 83 62 86 / 0 0 0 0
GIF 54 81 57 84 / 0 0 0 0
SRQ 54 79 59 82 / 0 0 0 0
BKV 42 80 50 84 / 0 0 0 0
SPG 61 76 62 79 / 0 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION/MARINE/FIRE WEATHER...42/Norman
UPPER AIR/DECISION SUPPORT...24/Hubbard