Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/28/20
Area Forecast Discussion
National Weather Service Goodland KS
1000 PM MDT Tue Oct 27 2020
.SHORT TERM...(This evening through Friday)
Issued at 220 PM MDT Tue Oct 27 2020
Main concern will be the upper low moving across the southern
plains and whether or not the associated precipitation makes it
into the forecast area. Secondary concern will be impacts of
lingering snow cover on temperatures.
Models in better agreement today on how far north precipitation
will move tonight through Wednesday night. GFS keeps all
precipitation south of the area while the ECMWF has only very
light amounts in northwest Kansas south of Highway 40, and really
most south of Highway 96. Latest runs of the HRRR support the dry
GFS solution. So will remove any mention tonight through Wednesday
morning of weather and precipitation. Wednesday afternoon and
evening may see some very light rain move into the southeast
corner of the area, Logan and Gove counties, possibly a rain/snow
mix after sunset, but even then precipitation likely to remain
south. By late Wednesday night, thinking all the precipitation
chances will be moving east. In summary, not expecting any impacts
in the forecast area from this system moving to the south.
As for temperatures, will be dependent on melting of the snowpack
in most areas. Southern areas appear to have received less snow
per visible satellite, but fairly broad swath runs from Norton
County to Cheyenne County in Colorado. Well lean towards the
cooler guidance in those areas, and blend towards the model mean
in the southern areas. Tonight will be cold again with lows in the
teens, but wind chills will remain well above criteria. Highs
tomorrow will be in the 30s and 40s with increasing clouds also
impacting temperatures. Wednesday night we will be closer to
normal with lows in the 20s. Thursday and especially Friday will
be much warmer, with highs in the 40s/50s Thursday and 50s/60s by
Friday and mostly sunny skies both days and light winds.
.LONG TERM...(Saturday through Tuesday)
Issued at 100 PM MDT Tue Oct 27 2020
For the long term, Saturday will start with a shortwave trough aloft
and a potential cold front near the surface. The front is starting
to appear more in the guidance than previous days, though there is
still lingering uncertainty with this front. Latest guidance moves
the front`s passage to midday which would cap high temperatures
during the early afternoon if this were to happen. Precipitation is
not expected with this front as a dry air mass is forecasted to be
over the area at least through Tuesday. However, latest runs have
some more moisture aloft, albeit not enough to currently justify
rain with this front. Will be worth watching in the upcoming days.
High`s are currently forecasted to reach the upper 50`s but this
could change in the coming days.
Sunday sees high pressure, associated with the colder air mass, move
into the Plains. However, the air mass looks to be east of our area
right now which would leave our Eastern locales with cooler high
temperatures than those near the Colorado border. The front the
prior day is still not expected to lower temperatures too much as
highs for Sunday are forecasted to remain in the 50`s across the
area. The main effect looks to be on the low temperatures for Sunday
morning as they are forecasted to drop into the mid to upper 20`s.
For Monday and Tuesday, the current forecast calls for dry
conditions and highs in the 60`s as surface high pressure remains
nearby and an upper ridge moves in from the west. Worth noting is
that the models really start to diverge from each other on the
timing of the passage of the ridge during the day Monday. However,
there should be no change in the general pattern for Monday and
Tuesday if the dry air mass remains in place for those two days.
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 957 PM MDT Tue Oct 27 2020
VFR conditions expected for the TAFs. Noticed that KMCK has a
slight reduction in visibility. Not expecting the dew points to
increase through the night, so am not anticipating fog to form.
Otherwise LLWS is occurring at KGLD, and should continue until mid
Area Forecast Discussion
National Weather Service Green Bay WI
1031 PM CDT Tue Oct 27 2020
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Wednesday
Issued at 225 PM CDT Tue Oct 27 2020
The latest RAP analysis and satellite/radar imagery show high
pressure centered across the central Plains to the southern Great
Lakes early this afternoon. Meanwhile, low pressure is diving
southeast across central Canada. Skies are mainly clear across
northeast Wisconsin, but clouds are surging southeast across North
Dakota and Minnesota within a mid-level warm advection zone ahead
of the low. Light wintry precip is falling over North Dakota
where the strongest warm advection is occurring. As this system
tracks southeast, light precip chances followed by temps are the
main forecast concerns.
Tonight...Low pressure will move towards northwest Lake Superior,
while the warm advection zone spreads east into northern WI and
the Upper Peninsula. Periods of broken cloud cover will likely
occur as ceilings lower overnight. But moisture is disjointed, so
mid-clouds depart as the lower clouds arrive late. As a result, no
precip is expected. However, the clouds and a breezy southwest
winds will keep temperatures much warmer than last night. Lows
ranging from the middle 20s to lower 30s.
Wednesday...A stronger shortwave will push a cold front across the
region. Forcing ahead of the shortwave and cold front is more
aligned, which may result in deep enough moisture for a chance of
light rain and snow near the U.P. border. Have kept a slight
chance of precip from the late morning through the mid-afternoon
in this area. Otherwise, west winds will be breezy under partly
sunny to mostly cloudy skies. Temps will be warmer and range from
the lower to middle 40s.
.LONG TERM...Wednesday Night Through Tuesday
Issued at 225 PM CDT Tue Oct 27 2020
Main concerns in the extend forecast will be the colder than normal
temperatures through the work week before warming toward the weekend.
Wednesday night: A weak trough axis is expected to pass through the
area Wednesday evening, before shifting to the east overnight. An
associated cold front will also pass through the area around the
same time period. Moisture looks to be fairly limited, with the main
precipitation remaining in the north to north-northwest wind lake
effect snow belts in of Vilas/Oneida County. Moisture looks to be
just deep enough to introduce ice crystals late in the night as
850mb temperatures drop to the -8C to -10C range. This would give
delta-T values across Lake Superior around 18C to 22C. Moisture is
fairly shallow, so not expecting much accumulation at this point
just some light snow showers or flurries. Lows are forecast to be in
the mid 20s to low 30s.
Thursday through Friday night: A surface ridge is expected to build
across the area through this time period as the mid-level flow
begins to flatten. This will lead to quiet conditions after any
morning lake effect snow showers end Thursday morning. Northeast
Wisconsin will be sort of the inflection point of rising height to
the west and troughing to the east, which will keep temperatures a
little below normal through this time period. Highs are expected to
be in the upper 30s to low 40s across much of the area. Overnight
lows will be mainly in the 20s.
Saturday through Sunday: As the surface ridge slides off to the east
of the area on Saturday, an area of low pressure will slide across
the Canadian/US border. The low is expected to slide from southern
Manitoba Saturday morning to western Quebec by Sunday morning. This
will drag a cold front across the area Saturday afternoon into
Saturday night. The system looks to be moisture starved, so not
expecting much precipitation from the system. Aloft, mid-level
heights rise through Saturday, allowing temperatures to warm into he
upper 40s to low 50s across much of northeast Wisconsin. Overnight
lows will drop into the upper 20s to low 30s.
Rest of the extended: Quiet weather is expected to continue into the
first part of the workweek as high pressure build into the area once
again. Temperature trends are expected to be near normal to begin
.AVIATION...for 06Z TAF Issuance
Issued at 1028 PM CDT Tue Oct 27 2020
Clouds dropped a little farther south than earlier anticipated,
but it`s a mid-deck so the flight category is still VFR. Expect
VFR conditions to prevail until very late tonight or Wednesday
morning, then lower clouds arriving in the north with result in
MVFR conditions. LLWS continue to SE across the area tonight.
Area Forecast Discussion
National Weather Service Louisville KY
951 PM EDT Tue Oct 27 2020
Issued at 945 PM EDT Tue Oct 27 2020
While KLVX radar is quiet, neighboring radars show some very light
returns in southern Indiana, which matches up well with the latest
HRRR for the upcoming 02z timeframe. Forecast sfc temperatures are
right on track, and match up with current Kentucky Mesonet obs. No
changes needed to the forecast, but just refreshed the upcoming
grids for the overnight hours with latest hi-res data. Still
thinking to see light drizzle or sprinkles overnight and into
Wednesday morning along with a very low cloud deck that is evident
on model soundings. Due to minimal changes, no updated products are
needed at this time.
.Short Term...(This evening through Wednesday)
Issued at 255 PM EDT Tue Oct 27 2020
Expect light rain across southern Indiana to diminish leading to
possible light drizzle or sprinkles overnight into Wednesday morning
before showers move in from the south Wednesday afternoon. Model
soundings continue to show a drizzle/sprinkle signal as low levels
are saturated to above 850mb beneath a subsidence inversion.
Isentropic lifting north of the quasi-stationary boundary draped
across southern TN will provide subtle lifting, adding some
confidence of seeing light liquid precip overnight into the morning
Cut off upper low over the SW US will continue its eastward
progression through the short term and be positioned roughly over
northern TX by Wednesday evening. This feature will interact with TS
Zeta as it makes landfall on the LA coast and continue to move NE.
This interaction will result in increased chances of showers by
Wednesday afternoon with more moderate to heavy rainfall possible
across our southernmost counties by early evening. Impacts and
accumulations will be discussed in the long term section below.
.Long Term...(Wednesday night through Tuesday)
Issued at 230 PM EDT Tue Oct 27 2020
...Heavy Rain Wednesday Night and Thursday...
...Frost and Freeze Saturday and Monday...
Widespread rain will be ongoing at the start of Wednesday evening
for most of Kentucky, and spreading into Indiana if not already
there. Precipitable water pushing 2 inches will be pooled near the
warm front as it hangs up near the Ohio River. Initial wave of rain
could drop a fairly uniform 1.5 to 2 inches of rain during the
course of Wednesday night, and we`ll have to watch where the warm
front hangs up before the upper wave pushes through on Thursday.
Currently looks like our southern Indiana counties, and probably the
northernmost tier of counties in Kentucky could pick up an
additional 1-2 inches on Thursday before the deep moisture pushes
off to the east in the afternoon. Main bust potential is across
southern Kentucky where a dry slot could cut into rainfall totals.
By Friday night, Canadian high pressure over the Great Lakes will
sprawl SW across the Ohio Valley, giving us a cool air mass and
favorable radiational cooling conditions. Sat morning min temps in
the mid 30s and light winds will support frost in just about any
non-urbanized area, but wet ground will be the main limiting factor.
A weak front swings through on Sunday, and the models try to
generate some very light QPF. However, this system appears quite
moisture-starved at this time, so precip chances are actually very
slim. A stronger sfc ridge and cold advection pattern will follow,
so frost and even freezing temperatures are possible Sunday night
and Monday night, perhaps ending the growing season.
.Aviation...(00Z TAF Issuance)
Issued at 730 PM EDT Tue Oct 27 2020
Not much change from the previous aviation forecast. Expect to see
continued MVFR and even IFR conditions through tonight and tomorrow.
KLVX continues to show light rain/drizzle across southern Indiana,
which should continue for the overnight hours at all sites. Winds
will remain light and mostly from the north throughout the first 12
hours, but look to become northeasterly after 16z or so. We could
see some improvements to MVFR (above fuel alternate) for HNB/SDF
after 16z, but showers from the south will be ramping up and will
extend restricted cats for BWG (and eventually all other sites
further beyond this TAF period).
Issued at 230 PM EDT Tue Oct 27 2020
Widespread heavy rain is expected Wednesday night and Thursday, with
total rainfall of 3-4 inches possible in portions of the area. With
the rainfall spread over a 24-36 hr period, we don`t expect flash
flooding, but where the heaviest rain falls, substantial rises will
be possible on streams and rivers later Thursday into Friday.
Expect a fairly uniform 1.5 to 2 inches of rainfall on Wednesday
night, which could result in some short-term ponding, especially in
poor drainage areas, but will mostly just saturate the ground. Where
the rain band stops moving north on Thursday morning, an additional
1-2 inches of rain will be possible, and could result in localized
flooding of small streams, and eventually rivers approaching flood
stage. Current forecasts suggest the greatest risk of river flooding
will be on the Blue and Muscatatuck Rivers in Indiana, the Green and
Rough Rivers in Kentucky, and Drakes Creek and Elkhorn Creek.
The best chance of excessive rainfall will be over southern Indiana,
but the exact placement of this rain band remains uncertain. A
Hydrologic Outlook will be issued for the whole area, but we will
hold off on any Flood Watches until we can refine where the heaviest
rain will fall.
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
650 PM CDT Tue Oct 27 2020
308 PM CDT
Through Thursday night...
Through Thursday night the first weather message of note is a
chilly night tonight with 20s for lows, although how far into the
20s and how much of the area being dependent on cloud cover.
Second, the likelihood of some rain south of I-80 late Wednesday
night into Thursday. The trend with this has been slightly further
south which looks to keep the potential for higher impact weather
also to the south of the CWA.
The pesky drizzle is finally shunting eastward this mid-
afternoon, being escorted by the right entrance region of a 150
kt upper level jet and a 90 kt mid level speed maximum. Visible
satellite imagery still indicates thicker cloud cover in the
southeast forecast area (along and east of I-55 -- especially
northwest Indiana). Low-level isentropic ascent in the 285-290K
layer has weakened from earlier but still subtle ascent indicated
by the RAP through early evening, and light echoes on TDWR data
continue to translate across the southeast forecast area with
spotty drizzle observations. So with the idea of some collision
and coalescence in the lower clouds there, have a mention of
patchy drizzle through early evening.
The low clouds have been gradually getting shunted out of the
northern forecast area, however mid and high clouds are reaching
the far northern CWA, being slung up here ahead of the potent
closed upper low over New Mexico. This makes it particularly
challenging to time cloud cover departure tonight. No matter what
it should be gradual over the central and southern CWA, with the
overall thought being by daybreak that much of the CWA is clear
with flow aloft turning more westerly as opposed to southwesterly.
Also adding a little wrinkle into things is that southwesterly
low-level flow starts to increase over the north by overnight,
which may result in temperatures flat-lining after reaching
minimums near midnight or so. Have lows forecast in the mid 20s in
outlying areas north of I-80 while trending more lower 30s south
and in the central part of the Chicago metro. It should be noted
there is a fair amount of bust potential especially on the hour-
by-hour temperature forecasts. Also it`s a non-zero potential
there could be some fog mainly in the central and southern CWA if
that area can clear without seeing a large drop in dew points.
Wednesday will have southwesterly winds which should bring some
gusts to 20 even 25 mph. The flow pattern does steer up 850 mb
temperatures around 8C, although that`s likely to be above the top
of the mixed layer (not surprising for late October), so 925 mb
temperatures of 5C seem more reflective on where highs could
reach. Climatology would favor lower to mid 50s with those values
and there should be a fair amount of sun at least in the morning.
Our next chance for precipitation will come late Wednesday night
into Thursday as a closed upper low tracks eastward into the
southern Plains and encroaches upon the path of Hurricane Zeta,
which will be making landfall in southeastern Louisiana Wednesday
evening. The two systems will interact and the end result of this
will feature a conglomerate of moderate to heavy rainfall expanding
northward into the Ohio Valley and southern Great Lakes. Some of
this precipitation should end up crossing into our southern CWA, but
exactly how far north that will be remains to be seen. Guidance has
trended towards keeping the northern extent of the precip shield a
bit farther south than indicated yesterday, but areas along the
Kankakee River Valley and southward still look to have a good chance
of at least seeing a few hours of rain overnight Wednesday into
Thursday. Areas north of I-80 are currently looking they should stay
mostly dry during this period, but even if this precip shield does
stay confined farther to the south, there is a non-zero potential
for some light lake-effect rain to develop along the Illinois
Lakeshore Thursday afternoon.
The surface pressure gradient will tighten in response to the
approaching surface low, and as a result, north-northeasterly winds
could become quite gusty Thursday afternoon. Will have to continue
to watch for the potential for some minor lakeshore flooding as
waves on Thursday look poised to make this a problem along both the
Illinois and Indiana shores. Otherwise, cloud cover will help keep
high temperatures only around 50 again on Thursday.
243 PM CDT
Friday through Tuesday...
Heading into the Halloween weekend through early next week, a
progressive pattern will continue to support dry conditions and
variable temperatures with highs ranging from the upper 40s to mid-
upper 50s and lows generally in the 30s...or close to norms for late
October and early November.
Friday looks like a repeat of Thursday in terms of temperature
trends but with a surface ridge moving in overhead the breezy
northeast winds should be diminishing. This would allow for a
slightly more comfortable afternoon on Friday compared to Thursday.
Halloween itself looks like it will fit its climatology
almost perfectly with highs in the mid 50s and lows that night in
the mid-upper 30s. This would be about 20-25 degrees warmer than
last year, and without any snow. The one inconvenience looks to be a
return of breezy winds, this time from the south, that could gust
over 20 mph for a while that afternoon.
A cold frontal passage Saturday night looks dry but will bring a
return of cooler and possibly even gustier northwest flow for
Sunday. The passage of the next surface ridge quickly follows and
allows the area to move back into the milder southerly flow on its
back side for Monday and Tuesday. Tuesday actually could see some
locations push toward 60 degrees, but again with gusty southwest
For the 00Z TAFs...
Drier air continues to press into the region here this evening,
with the last vestiges of IFR and MVFR cigs peeling out of MDW and
GYY. An expansive mid-level deck will take a bit more time to push
south of the terminals. The main question tonight is the degree of
clearing that we see which will essentially dictate the potential
for brief IFR cigs and/or patchy BR. Upstream satellite imagery
reveals a rather expansive area of mid-level stratus and high
cloud cover which will curtail the degree of cooling/moistening in
the near-surface layer this evening. Some guidance hints at a bit
of thinning taking place towards midnight, and if this were to
take place, dewpoint depressions of only a handful of degrees
would be quick to fall to near 0 supporting the development of at
least localized BR and IFR/LIFR cigs. At this time, confidence is
too low to justify any formal mentions of reduced cigs/vsbys in
the TAFs, but MDW and GYY would seem to have the main potential
given their location away from the slightly faster flow
immediately off the deck and higher dewpoints. We`ll keep an eye
on trends this evening.
Otherwise, no significant aviation weather concerns through
tomorrow with increasing high-level cloud cover through the day
ahead of the robust upper low spiraling across the New Mexico
Bootheel. Could mix into some sporadic 20 kt gusts by late morning
and into the afternoon. We`ll then turn our attention to a cold
front which will deliver a (gradual) northwest wind shift
Wednesday evening, and a more noticeable breezy northeast wind
shift overnight into Thursday morning.
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Area Forecast Discussion
National Weather Service Nashville TN
854 PM CDT Tue Oct 27 2020
FOR EVENING DISCUSSION.
Isolated light shower activity indicated on the radar this
evening. Hrrr indicating that these returns will continue
overnight with an increase in coverage and intensity across
southern areas as we approach dawn. Current regional radar showing
the more widespread activity across the south half of AL. Models
in agreement with deeper moisture spreading northward across AL
For the update, will begin the slight chance of showers a little
earlier this evening and will update the grids accordingly to
reflect this. Remainder of fcst looks to be in good shape. Current
dewpoints are very close to expected lows. Update out shortly.
00Z TAF DISCUSSION.
After some MVFR cigs this afternoon, conditions will begin to
worsen overnight into tomorrow. Expect cigs to lower slowly
through the night with periods of mist/fog in the early morning.
Widespread shower coverage will move from south to north through
the daytime likely impacting all terminals with low cigs and vis
at times. Expecting IFR to LIFR conditions across the area
beginning with CSV in the morning, followed by BNA/MQY around
lunchtime, and CKV by tomorrow afternoon.
Winds will remain light through the TAF period, gradually shifting
from northerly to more easterly by tomorrow afternoon.
Area Forecast Discussion
National Weather Service Blacksburg VA
808 PM EDT Tue Oct 27 2020
A frontal boundary will remain stalled over the region as Zeta
makes landfall on the Gulf coast by Wednesday night. As Zeta
approaches the Appalachians and central mid Atlantic region, it
will interact with the stalled frontal boundary to bring
widespread rainfall to the area by daybreak Thursday. A cold
front will move through on Friday, sweeping away the remnants
of Zeta and ushering in much colder weather for the weekend.
.NEAR TERM /THROUGH WEDNESDAY/...
As of 750 PM EDT Tuesday...
No significant changes are planned at this time. Temperatures
and dewpoints were running a bit higher than advertised, so they
were lowered accordingly to match current observations. Minimum
temperatures overnight were raised a few degrees in accordance
with the HREF/HRRR latest guidance. Finally, added more fog as
latest HRRR visibility shows similar situation to last night
across the Piedmont, although am a bit concerned that an
increase in clouds may preclude this somewhat.
As of 215 PM EDT Tuesday...
GOES-East visible satellite imagery shows that much of the early
sunshine was self-destructive as moisture in the boundary layer
bubbled up a robust Cu/Sc field. Expect there may be some decrease
in clouds this evening before clouds bloom once again overnight
and fog develops.
Any improvement Wednesday morning will give way to deteriorating
conditions as Zeta approaches and buckles the flow, generating a
good push of isentropic lift into the region later in the day
and spreading showers into the area from the southwest.
Temperatures will be seasonable with lows tonight in the 50s and
highs tomorrow ranging from the middle 70s east of the Blue
Ridge to the mid/upper 60s west.
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 400 AM EDT Tuesday...
The short range portion remains focused on the remnants of Zeta
passing over the area while an upper level low/trough follows
shortly behind. While this tropical system will be moving very
quickly, the provided environment when it passes will be more than
efficient to drop very heavy rainfall in a short period of time,
meaning flash and river flooding risks are high. Likewise, the
strong winds aloft for both Zeta and the trough pose a wind damage
threat, especially once factoring in the saturated ground once the
rain starts. While not a high/widespread threat, shear provided by
Zeta will provide a low but ever present threat of a tornado or two
with low topped, rotating, supercells Thursday.
Breaking down the forecast, Wednesday night will start with a warm
front being driven northward with high pressure situated off the
southern Atlantic coast while Zeta makes landfall. These two systems
together should work to drive abundant tropical moisture northward
into the Mid-Atlantic. PWATs Wednesday night into Thursday are
expected to swell past 2", which is roughly 3 standard deviations
above normal...so a very saturated airmass moves into place. This
lifting warm front will already provide the lift needed to drive rain
chances up, but upslope flow following behind the front thanks to
the Blue Ridge and NC Mountains, as well as potentially the eastern
side of the western slopes, should help drive locally higher
amounts. All of this said has lead to me bumping the rainfall
forecast up by .25" to .5".
During the day Thursday, guidance continues to lock onto a forecast
track that brings Zeta directly over our forecast area. That means
that strong, cyclonic winds area expected to pass directly overhead.
Based on guidance, I upped winds from the last forecast package. As
mentioned in the summary paragraph, this strong wind, now combined
with saturated soils, could lead to downed trees (thankfully leaves
are starting to fall as we near the end of the growing season, so
there won`t be as much drag). With strong cyclonic winds overhead,
it goes without saying that there will be an isolated tornado
threat: all of the shear components are there for this event, we
just lack CAPE for tall, defined supercells. Instead, anything will
come from low topped supercells. Location wise, they will be most
likely across the Piedmont, up again the Blue Ridge. However, with
an environment this sheared, I don`t think they could be ruled out
even up against the western slopes, which is further west than SPC`s
marginal risk. Heavy, persistent rainfall remains likely through
Thursday as we hit the peak in PWATs, with lighter rainfall taking
over Thursday night as Zeta exits to the east and synoptically driven
rainfall takes place. By Thursday night, we should be seeing the
peak in rivers across the region: current forecasts from RFCs don`t
bring any of our rivers to flood stage, but I think that may change
in the coming updates. Once again, the growing season is a big
contributor in this: while past tropical systems have come through
while everything has been growing and using up the water quickly, I
think this time around more water will make it into the rivers with
vegetation slowing down now for the season.
We dry and cool off Friday as the trough passes overhead, bringing
the cold front through. This brings a big change in temperatures as
we head toward the weekend with highs Friday expected to only top
off in the low 40s/upper 50s mostly. Cooler weather Friday night
could bring the need for frost/freeze headlines for parts of the
east where the growing season remains in affect.
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 215 PM EDT Monday...
A cold front moving through the Mid-Atlantic brings cooler weather
for the weekend. Despite high pressure building in for the day
Saturday, max temps will remain below normal making for a very cool
Halloween. High pressure over the region doesn`t last long with
another front expected Sunday to bring a reinforcing shot of cold
air. This second blast of cold air looks more than poised to bring
widespread FF headlines for the entire east based on current
guidance Monday AM. After that front, high pressure returns for the
region as we gradually see temperatures warm, trying to get us back
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 800 PM EDT Tuesday...
Generally poor to fair aviation conditions expected through the
TAF valid period. For tonight, the main concern will again be
fog. Models showing similar situation to last night with dense
fog developing quickly after sunset across the Piedmont area.
Confidence in this occurring to the degree of last night is less
because of greater amount of cloud cover. However, light winds,
moist ground, and some late afternoon/early evening clearing
does bode for fog development. Have tried to indicate the
potential for dense fog without hitting it too hard and too
long. Trends over the next few hours now will better determine
the degree to which fog will occur tonight. At any rate with the
long nights, available moisture, light southeast winds for the
most part, and favorable time of year, fog will most likely
develop in most if not all areas later tonight. The intensity is
the main question. Thinking MVFR to IFR a pretty good bet at
most sites except perhaps ROA and BLF.
For Wednesday, look for mostly MVFR ceilings after the fog
dissipates by mid-morning with ceilings hovering in the 020-040
range at most sites. Ceilings will begin to lower once again and
also mid and high levels will become overcast by afternoon as
the remnants of Zeta rapidly approach the region from the
southwest. Expect sprinkles or light rain to develop from the
south/southwest by 21Z and reach most TAF sites by 00Z. Heavier
rain will come after 06Z Thursday.
Winds will be light and variable but favor the southeast
overnight, then southwest during the morning Wednesday, then
begin backing toward the southeast and east and slowly
increasing in speed by Wednesday evening as the remnants of Zeta
approach from the southwest. Speeds through this period will
remain generally less than 7kts.
/Confidence Levels in Forecast Parameters/
Ceilings - Moderate to High Confidence in sub-VFR ceilings
throughout the TAF valid period,
Visibility - Moderate Confidence in sub-VFR visibilities
Winds - Moderate Confidence in SSE-SSW wind direction and High
Confidence in speeds of 5-8kts through the TAF valid period.
.Extended Aviation Discussion...
Thursday will bring widespread rain and potentially some low end
gusty winds associated with the remnants of Zeta, mainly 06Z
Thursday through 18Z Thursday. Then a strong and highly
kinematic upper trough will quickly follow behind Zeta for late
Thu-Friday. Poor aviation conditions and mainly MVFR or worse
are expected Thursday into Friday morning. High pressure and
much cooler/drier conditions are expected in the wake of these
weather systems by the weekend. Westerly flow may result in some
lingering clouds across the western mountains into Saturday, but
this should not last long into the weekend.
Area Forecast Discussion
National Weather Service Shreveport LA
852 PM CDT Tue Oct 27 2020
Stalled frontal boundary continues to be located just offshore the
SE TX Coast into Central MS with a weak sfc trough located near a
Huntsville, Tyler Texas to Idabel Oklahoma line. Taking a look at
01z temps, temperatures near and northwest of the I-30 Corridor
were either at their fcst min temp or a degree or two below it as
patchy fog (dense in some places along with patchy drizzle) has
resulted in temperatures falling below their dewpoint
temperatures. As we go through the remainder of the night, would
not be surprised to see temperatures warm slightly but did lower
temps near and northwest of the I-30 Corridor just a few degrees.
Concerning pops, quite a spread in the guidance as to just how
much precipitation we will see overnight as the HRRR is trending
on the drier side of guidance with the 18z NAM very wet with
increasing PVA from the south. For the update, have shaved pops
just slightly near and south of a Tyler to El Dorado line, still
keeping pops in the likely category but north of this line,
keeping middle end chance pops going. Feel like any chance of
seeing isolated TSRA will likely be reserved for after midnight
towards sunrise Wed so made this change as well.
All other grids are in the ballpark with a very wet day expected
areawide on Wednesday as the upper level trough continues to
approach our region from the west.
.PREV DISCUSSION... /issued 646 PM CDT Tue Oct 27 2020/
Widespread IFR ceilings will only detiorate as we go through the
night with the development of scattered to numerous areas of
precipitation and that will continue through the day Wednesday as
well as a deep upper level low approaches our airspace from the
west. Lapse rates are not all that great but did include some TSRA
through at least the morning hours across our airspace on
Wednesday. Should see precipitation trying to come to an end
across the western third towards the tail end of this TAF period
along with a frontal passage from west to east during the tail end
of the TAF period as well.
.PRELIMINARY POINT TEMPS/POPS...
SHV 57 62 44 57 / 60 100 50 10
MLU 58 70 48 61 / 60 100 70 10
DEQ 50 57 43 54 / 40 90 80 10
TXK 50 56 43 54 / 50 100 70 10
ELD 51 60 45 57 / 60 90 80 10
TYR 50 55 41 55 / 60 90 20 0
GGG 54 58 42 57 / 60 90 30 0
LFK 59 64 43 61 / 60 90 20 0