Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/30/21
Area Forecast Discussion
National Weather Service Dodge City KS
555 PM CST Fri Jan 29 2021
...Updated Aviation...
.SHORT TERM...(This evening through Saturday)
Issued at 331 PM CST Fri Jan 29 2021
The boundary layer is showing southerly flow at around +14 to +16
deg C at 850 mb impinging on a very cold surface layer over northern
Kansas, where a stationary front is straddled east to west just
north of the I-70 corridor. The widespread freezing fog has
remained north the Hays vicinity though the early afternoon and
temperatures elsewhere have been slow to respond given the
increasing/extensive cloud cover over the area. The HRRR and
RAP13km/HiResARW models all keep the redevelopment of dense fog
north of I-70. However GFSLAmp indicated high probability for
VLIFR type ceilings to rapidly develop around 09Z as the rain and
possibly brief freezing rain lifts rapidly north into central
Kansas before dawn. Basically, we do not anticipate high
probability of needing a dense fog advisory at this time, however
if conditions deteriorate late this evening, those areas along
and north of I-70 would be the prime areas.
.LONG TERM...(Saturday night through Friday)
Issued at 331 PM CST Fri Jan 29 2021
Warm conveyer belt type surge of lift and moisture will spread over
roughly the southeast third of the area, with reasonably high
confidence. Surface dew points surge into the 40s. Far southeast
sections of the area should see at quarter inch of rain or
possibly much higher. The NAM12 prints out areas of minimal, but
still some convective precipitation inferring some instability
present southeast of Dodge City.
The period of rain will be brief as the low pressure moves out
quickly and deep northwest flow takes over the rest of the
afternoon. Strong 30-35 knot winds in the boundary layer should
result in very strong gusts through the daytime hours, and even
"weaker" still windy conditions going into the evening hours over
western Kansas. Right now the GFSLAMP guidance is showing strong
wind speeds around 30-33 knots sustained in the early afternoon
Saturday across the most windy region (GCK/LBL), with gusts around
40 knots. Model output from the IEM meteograms generator for
momentum transfer indicate potential for 50 knot gusts for a
couple of hours, but many more remain well below the 50 knot gust
threshold for High Wind.
The extended period still looks active as the westerlies buckle
to a longwave ridge over the Great Plains Monday and Tuesday with
the high probability of a negatively tilted synoptic scale cyclone
impacting the central plains by mid to late week (Wednesday night
into Thursday night). At this time, the consensus of ECMWF/GFS
would place best chances for the heavy precipitation axis
somewhere from western Iowa into northwestern Kansas.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 552 PM CST Fri Jan 29 2021
VFR flying conditions are expected at all terminals for roughly
the first 12 hours of this TAF period. Around 12Z tomorrow, low
cigs and associated rain will move in from the south bringing DDC,
GCK, and HYS into MVFR/IFR through the early afternoon. LBL will
likely avoid a drop in flight category, but a glancing blow of
MVFR cannot be ruled out. There is also a slight chance of
freezing rain/sleet near HYS in the late morning and early
afternoon, but confidence is too low to mention in the TAFs.
Shortly before sunset, all precipitation is expected to move out
of southwest Kansas, and all terminals should return to VFR.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 38 50 29 49 / 40 90 0 0
GCK 32 50 27 49 / 20 40 0 0
EHA 36 57 29 53 / 10 10 0 0
LBL 40 57 28 53 / 30 20 0 0
HYS 30 40 26 42 / 20 50 0 0
P28 44 55 30 49 / 100 90 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Russell
LONG TERM...Russell
AVIATION...Springer
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
541 PM CST Fri Jan 29 2021
...AVIATION UPDATE...
.DISCUSSION...(This evening through Friday)
Issued at 351 PM CST Fri Jan 29 2021
Main concerns are dense fog tonight, wintry mix late tonight
through Saturday evening, and blowing snow potential from strong
north/northwest winds Saturday afternoon/night.
The last of the fog finally lifted, or at least improved in
visibility in our west, no thanks to the low sun angle of January.
The HRRR did a pretty good job with this compared to other
models/guidance. With conditions similar tonight and HRRR
indicating a return of fog from generally west to east, I have
high confidence of dense fog returning. Look for some light icing
from freezing fog, which will possibly impact roadways and make
them slick. Went with CONSRaw for lows tonight considering the
cloudy conditions and light fog developing, favoring a warmer
solution. Went with CONSShort/NBM temp combo for highs Saturday.
Adding insult to injury will be the potential for wintry mix/light
freezing drizzle with a stubborn dry mid-level forecast quite
consistently. Both the HRRR and NAM advertise the potential of
freezing drizzle through Saturday evening, save the short period
Saturday afternoon when we may be just above freezing. Models have
generally held ground or shifted southeast with the precip band of
a low moving across Kansas, with the noticeable exception of the
GFS ensembles nudging a bit northwest over the past few runs. The
NAM has even been trending southeast with precip. Taking this all
into account, I backed off QPF, shifting it southeast. Ice
accumulation, if any, would be light and same for any skiff of
snow that may occur. Still could be a bit of blowing snow,
especially farther northwest where it would be less likely to get
freezing drizzle to tamp down blowing snow. since we don`t have at
least likely POPs for Saturday, I opted away from issuing a winter
weather advisory. I did highlight slick conditions from freezing
fog development tonight/Saturday. In reality, it may be from both
freezing fog and freezing drizzle. The importance would be that
folks know that slick conditions are definitely possible.
Focused less for later in the forecast, but still on track for
moderating temps early next week and a significant system for
Wednesday night/Thursday, and could very well be a larger weather
maker than what we are getting tonight through Saturday night.
.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Saturday)
Issued at 1158 AM CST Fri Jan 29 2021
Biggest concerns are visibility and fog. Fog has held on longer
than earlier forecast and may stick around for at least a short
while this afternoon before returning. Most models and satellite
trends indicate that we will get a temporary reprieve from the
fog, especially in the more eastern terminal of KGRI. Fog is
almost a sure thing to come back and develop tonight along with
LIFR ceilings. Confidence is quite high in fog redevelopment and
there is widespread agreement among numerical models.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday)
Issued at 533 PM CST Fri Jan 29 2021
Another foggy night ahead, looking very similar to
today/yesterday. Cigs are expected to remain rather low...mostly
IFR and LIFR though there may be the occasional pocket of MVFR.
However, this will likely be inconsequential with dense fog
expected to develop over the next several hours (with
visibilities expected to be generally around 1/4 mi or less)
which will likely persist through most of the day tomorrow. During
the daylight hours though, visibilities may improve slightly to
around 1-2 mi.
Slight precip chances exist tomorrow afternoon, mainly for KGRI,
and both terminals will likely see blowing snow later in the
afternoon tomorrow and into the evening hours, with wind speeds
expected to pick up to around 20kts with gusts to around 25-30kts.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...Dense Fog Advisory from 9 PM this evening to noon CST Saturday
for NEZ039>041-046>049-060>064-072>077-082>087.
KS...Dense Fog Advisory from 9 PM this evening to noon CST Saturday
for KSZ005>007-017>019.
&&
$$
DISCUSSION...Heinlein
AVIATION...Shawkey
Area Forecast Discussion
National Weather Service Jacksonville FL
820 PM EST Fri Jan 29 2021
.UPDATE...
Forecast on track rest of tonight with light winds and clear
skies enabling excellent radiational cooling. Temps expected to
bottom out in the lower to mid 30s inland, with mid 30s to around
the lower 40s toward the coast. In addition to frost potential
inland areas, very patchy fog will be possible, mainly over inland
northeast FL, due to the influx of some low level moisture from
the east to northeast flow today. This is supported by HRRR and
SREF guidance.
.MARINE...
Just slight changes to the forecast to make wave dominant period
long period swells around 12 seconds rest of tonight, as wave
models about 12 hours behind on the east-northeast swell train.
Seas nearshore a little low some bumped up slightly. Otherwise, no
change to headline offshore.
&&
.PREV DISCUSSION [639 PM EST]...
.NEAR TERM [Tonight Through Saturday]...
High pressure extending over the Ohio and Tennessee Valleys will
weaken slightly and slowly shift east tonight and tomorrow, which
will keep conditions dry. Surface high pressure to our north will
result in light northeasterly winds tonight that will shift to be
easterly tomorrow as the high shifts to our northeast. Overnight,
winds will be calm and skies will be clear, resulting in strong
radiative cooling and cold temperatures. Low temperatures tonight
will be in the low-to-mid 30s in SE GA and mid-to-upper 30s in NE
FL. Low temperatures will be slightly warmer in the lower 40s in
north central FL and at the coasts. Frost is expected again
tonight at inland locations. Saturday will be warmer than today
with high temperatures in the lower 60s in SE GA and mid-to-upper
60s in NE FL. Cloud cover will begin to build throughout the day
ahead an approaching low pressure system moving east across the
Midwest.
.SHORT TERM [Saturday Night Through Tuesday]...
High pressure will be northeast of the region Saturday night, then
to the east on Sunday. A cold front will move southeast into western
counties late in the day Sunday, with much of the precipitation
expected to be on a prefrontal trough just ahead of the front
itself. The front will push to the southeast of the forecast area
Sunday night. Saturday night is expected to remain dry across
region, with much of Sunday day light hours dry as well for NE FL.
For far inland SE GA counties a line of showers, with embedded
thunderstorms to move in early afternoon. This area will move across
SE GA and Suwannee valley through the remainder of the afternoon
hours, then into coastal NE FL Sunday evening. Temperatures will
have a chance to surge east of this line along with dewpoints,
especially for NE FL, so potential for a few strong storms exist.
This potential will exist in SE GA as well due to better upper
support, despite the cooler temperatures.
Region will be between departing low to the northeast and building
high from the west Sunday night through Monday, as an upper trough
pivots southeast into area. Cold advection expected during this
period. Due to pressure gradient winds will remain elevated Sunday
night and become breezy during the day Monday. The upper trough will
help keep clouds across area, despite building surface high
pressure. The combination of winds and clouds will help keep
temperatures from falling off too fast for Sunday night. The cold
advection and cloud cover will yield a below normal day for Monday.
The upper trough will push toward the east Monday night as surface
ridge builds closer. This will yield decreasing clouds through the
night, with temperatures into the lower 30s inland. The continued
pressure gradient is expected to keep winds stirring enough to limit
frost potential though.
Sunshine is expected for Tuesday, but the cooler than normal airmass
will remain in place.
.LONG TERM [Tuesday Night Through Friday]...
The surface high will build overhead Tuesday night through Wednesday
morning, then toward the east late Wednesday. This pattern will
provide clear skies and fairly light winds. Tuesday night will
likely be the coldest night of the week, with a fairly widespread
frost and freeze potential away from coast. A sunny day is expected
for Wednesday, with temperatures rising closer to seasonal averages
as the afternoon flow trends more from the south due to position of
the high.
The high will build toward the east northeast Wednesday night through
Thursday. This will yield an increasingly warm southerly flow.
As the high moves further to the east Thursday night, and a cold
front approaches from the west, moisture will increase across the
area. Models do diverge in timing of this frontal system. GFS brings
front in later in the day Friday, while the ECMWF keeps it to the
west through this period. Given expected strength of the high,
the slower progression to the low makes sense, so will trend with
toward the drier solution late in this period. This will keep the
warm southerly flow going into Friday, with temperatures well
above normal.
.AVIATION...
[Through 00Z Sunday]
Light to calm winds and nearly clear skies will prevail through
Saturday morning. Winds will become easterly Saturday mid-morning,
then east-southeast Saturday afternoon near 10 knots. Increasing
onshore flow will lead to more cumulus/cloud coverage during the
aftn. SREF guidance suggesting MVFR ceilings for Saturday around
and after 18Z, but due to chances being below 40 percent, it was
not placed in the TAFs.
.MARINE...
High pressure will build to the northeast of the region Tonight
through Saturday night. The high will build more toward the east
Sunday, as a cold front approaches from the west. The cold front
will move southeast across area Sunday into Sunday night. On Monday
the region will be between low pressure to the northeast and high
pressure building to the northwest. The high will continue to build
from the west Monday night through Tuesday, then overhead for
Wednesday. The high will build toward the east Thursday, with a cold
front approaching from the west Friday.
Rip Currents: SE GA Moderate through Saturday
NE FL Trending toward High for Saturday
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 32 62 47 68 45 / 0 0 20 80 40
SSI 39 59 52 69 48 / 0 0 10 50 70
JAX 36 64 52 74 48 / 0 0 10 20 60
SGJ 43 64 54 74 50 / 0 10 0 10 60
GNV 37 68 50 74 48 / 0 0 0 20 70
OCF 38 70 51 76 50 / 0 0 0 10 70
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1025 PM EST Fri Jan 29 2021
.UPDATE...
Issued at 1025 PM EST FRI JAN 29 2021
Mostly clear skies, light winds, and dry dewpoints are leading to
a good night of radiational cooling with a small ridge to valley
temperature split opening up. This will be mitigated somewhat by
high clouds moving in from the northwest later tonight. The
current forecast has this all well in hand and have mainly just
touched up the T and Td grids per the latest obs and trends. These
freshened grids have been sent to the NDFD and web servers.
UPDATE Issued at 645 PM EST FRI JAN 29 2021
23z sfc analysis shows high pressure over the Ohio Valley
and keeping skies mostly clear and winds light this evening.
Temperatures are running in the upper 20s to lower 30s while
dewpoints are mostly in the mid teens. Have updated the grids
mainly to add in the current obs and trends for the T/Td ones.
These updates have been sent to the NDFD and web servers.
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 425 PM EST FRI JAN 29 2021
Late this afternoon an upper level low was centered southeast of
Cape Cod while an upper level ridge extended from Mexico north
through the central Conus. Northwest flow aloft is currently in
place across eastern KY at this time between the trough to the
east and the ridge axis to the west. Further west, a trough was
moving across the southwestern Conus. Mid level clouds had been
rather persistent near and just east of the northern and eastern
fringes of eastern KY, but has begun to diminish. At the surface,
an area of high pressure a ridge of high pressure extends from the
Great Lakes across the OH Valley and into the southeast Conus.
With the airmass starting to moderate, temperatures outside of the
high terrain reached the 30s. The airmass remains dry, however,
with dewpoints ranging through the teens.
Tonight, the trough to the northeast and east of the area is
expected to begin to shift east of the area while the axis of the
upper level moves into the eastern Conus. At the same time, the
trough moving across the southwestern Conus will work across the
Four Corners and reach the plains late. Sfc low pressure should
begin to develop/organize to the lee of the Rockies over the high
Plains in the western OK panhandle vicinity in advance of this.
The axis of the upper level ridge is expected to move east of the
area during the day on Thursday while the trough closing off to an
upper level low moves quickly across the Plains and nears the mid
MS Valley Saturday evening. The upper level low should track into
the northern IL vicinity by the end of the period. Meanwhile, the
sfc low is expected to track into western MO early on Saturday
evening and reach near the confluence of the OH and MS Rivers late
in the period. Isentropic lift associated with a warm front and
forcing in advance of the upper level low/trough and deepening
sfc low is expected to lead to increasing as well as thickening
and lowering clouds on Saturday, particularly from late in the
morning through the afternoon. Moistening up from the top down
appears likely despite a dry airmass to begin the day and
measurable precipitation may fall during the evening as the warm
front lifts northeast across the area.
The initial dry air and associated wetbulbing of the column may
result in a mix of rain and snow with this band lifting northeast.
As the lower levels continue to saturate a brief window where
freezing rain may be possible if temperatures reach the freezing
mark cannot be ruled out along the northern and eastern fringes of
the area in the higher terrain generally above 2500 feet. These
highest elevations could also experience snow on the leading edge
of the main band of precipitation associated with this low that
arrives later in the evening and into the overnight. Continued
warm air advection should lead to all rain in the highest
elevations toward dawn. The 18Z HRRR appears holds onto snow
about as late as any guidance and has a few inches on the top of
Black Mountain. The 12Z HREF PMM has much less for the top of
Black Mountain. Overall, opted to go with a compromise among the
guidance, allowing for wetbulbing of the lower levels to lead to a
rain and snow mix generally over the north and east with the
initial band in the late afternoon and evening as well as with the
leading edge of the main band of precipitation late in the
evening into the early portion of the overnight. Most locations
should be too warm not experience any accumulation, but some light
accumulations cannot be ruled out north of the Mtn Pkwy.
especially near and north of I 64 as well as in the elevations
above 2500 feet.
Sfc and upper level ridging shifting across the area will set the
stage for the eastern and northeastern valleys to be the coldest
tonight, with readings as low as the mid teens anticipated there.
Ahead of the increase in clouds on Saturday, temperatures should
moderate to the 40s outside of the highest terrain. How heavy the
precipitation is with the leading edge is uncertain and this will
modulate how much wetbulbing occurs late in the afternoon and
evening, leading to uncertainty in hourly temperatures there.
.LONG TERM...(Sunday through Friday)
Issued at 514 PM EST FRI JAN 29 2021
The long-term period begins Sunday morning with troughing over
the heart of the nation and its parent cutoff upper level low
centered over northern Illinois. A building upper level ridge will
be situated well to our west along the Continental Divide. At the
surface, an ~1000mb surface low will be found over southern
Illinois. Multiple fronts and troughs will originate from this
surface low, the first of which will be a warm front along the
Ohio River. This warm front will be responsible for a period of
rain and mixed precipitation Saturday night and early Sunday
morning. Another cold occluding front will extend southward from
the low into Tennessee. A secondary cold front and multiple
surface troughs will be radiating outward like spokes along the
western and northern portions of the low.
12z Sunday-00z Wednesday...
Rain showers, associated with the leading warm front, should
taper off for most locations Sunday morning as a dry slot wraps in
around the southern side of the storm system. GFS and HRRR model
soundings suggest that the clouds should thin enough for at least
partial sunshine to break out during the morning and early
afternoon, particularly south of the Mountain Parkway. The clouds
and a few spotty showers will likely remain more stubborn north
of the Mountain Parkway due to the proximity of the surface low
passing along the Ohio River. Temperatures should be quite mild,
warming into low to mid 50s south while northern locations stuck
under the clouds will probably stay in the 40s. Late in the day,
the low`s occluded front will push from west to east across the
forecast area. Model soundings appear to supportive of a broken
line of shallow convection with this front, but equilibrium levels
warmer than -10C would not be supportive of thunder.
During the overnight on Sunday night, the filling surface low
will move to near Huntington, WV while a new triple point low
takes shape along the North Carolina Coast. As this occurs, a
secondary surface cold front will pivot around the backside of the
filling low turning winds more northerly over the Commonwealth
which will usher in colder air and wrap-around moisture. At the
same time, the upper level trough/low will amplify sharply,
causing the coastal to low to blossom into a full-fledged
nor`easter off the Mid-Atlantic and Northeast coast. While we
won`t see direct impacts from this storm, a tightening pressure
gradient and deep troughing will keep plenty of low to mid-level
moisture and a northwest to northerly upslope flow over the
forecast area Monday into Tuesday. This will lead to a periods of
upslope snow showers, likely enhanced by upper level vort energy
Monday afternoon and night. However, model soundings are rather
unimpressive, showing fairly stable conditions above a shallow
boundary layer and the best omega generally below the dendritic
growth zone. Thus mainly smaller crystals are expected leading to
lower SLRs and a denser snow. Additionally, temperatures will
only be marginally cold at lower elevations, causing some or most
of the snow which falls during the daylight hours to melt. Above
1,500 feet, daytime temperatures will be a little cooler, around
freezing or colder, which will be more supportive of some light
daytime accumulations. Some impacts on the Monday
afternoon/evening commute are possible through the higher gaps.
Temperatures cooling off into the mid and upper 20s Monday night
will be supportive of light accumulations area-wide.
Any notable upper level forcing exits early Tuesday morning as a
subsidence inversion lowers ahead of incoming ridge axis; but,
trapped low-level moisture in the northerly flow off of the Great
Lakes will likely result in continued cloudiness and scattered
upslope flurries over the hills and mountains east of I-75 through
much of the day on Tuesday. Daytime temperatures will again be
chilly only topping out in the low to mid 30s, although a few
upper 30s are possible west of I-75 where more in the way of
sunshine is expected.
00z Wednesday-Friday
The timing of the clearing Tuesday night will be dependent on how
quickly our northerly moisture feed cuts off, but most models do
suggest that high pressure will eventually prevail and clear the
skies. The combination of light winds, very dry air aloft, and any
lingering snow cover will be nearly ideal for rapid radiational
cooling once the skies clear. Lows are currently forecast to range
from the upper teens to lower 20s; but, if the clearing occurs
earlier in the evening, temperatures could drop several degrees
lower, especially in those sheltered snow-covered valleys. After
a cold morning, high pressure will ensure a mostly sunny day on
Wednesday with temperatures rebounding into the 40s. As the next
system approaches Wednesday night, significant differences are noted
among the models. The operational Canadian appears to be an
outlier solution and has been ignored. Both the GFS and ECMWF show
a rapidly deepening low lifting from near the Oklahoma Panhandle
to near James Bay by the end of the forecast period but disagree
on the system speed and track. The GFS features a faster and more
northerly tracking system with some light WAA precipitation
Wednesday night followed by a cold front and a period of rainfall
from late Thursday into Friday. The ECWMF keeps the WAA
precipitation north of the forecast area and is about 12 hours
slower and quite a bit wetter with the cold front. Regardless of
how this system plays out, thermal profiles indicate that the
precipitation will probably remain all liquid. Temperatures on
Thursday should easily reach in the 50s before cooling off behind
the cold front.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 655 PM EST FRI JAN 29 2021
VFR conditions and light winds will continue through the period
as a ridge of high pressure slides across the area. Late in the
period, moisture will begin to increase ahead of an approaching
system, with an increase in high clouds and some mid clouds likely
arriving towards 18Z. These clouds start to lower with a band of
light mixed pcpn expected to pass through the terminals by 00Z
Sunday.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...JP
LONG TERM...GEERTSON
AVIATION...JP/GREIF
Area Forecast Discussion
National Weather Service Marquette MI
1022 PM EST Fri Jan 29 2021
.SHORT TERM...(This evening through Saturday)
Issued at 238 PM EST FRI JAN 29 2021
Water vapor imagery and RAP analysis shows a closed low off the
coast of New England with troughing from ne Canada into the ne
CONUS. Another mid-level trough is moving onto the West Coast.
Between these flanking troughs is a broad ridge centered across the
Plains states. As models indicate shortwave energy rounding the base
of the long wave trough through southern CA this afternoon, it will
then split and drive through the Southern Rockies tonight and the
Southern Plains on Sat. This will effectively amplify the mid-level
ridging into the Western Great Lakes tonight into Saturday which
should result in mostly dry conditions, except for some nw flow
flurries into the eastern counties this morning and maybe a light
dusting of WAA snow/flurries west half Sat morning. WAA/isentropic
ascent ahead of the Plains system will result in increasing mid-
level clouds late tonight into Saturday for the west and central
U.P. while the eastern part of the U.P could see some clearing late
this evening into Sat morning before clouding over Sat afternoon.
Min temps will be tricky tonight as there will likely be a window
over the interior west half this evening where temps could fall
pretty quickly into the single digits under clear skies and
generally light winds. Lake clouds and flurries persisting into the
east this evening under a light nnw flow will keep temps a bit
warmer there into the evening. Conditions will then flip overnight
as se winds and mid-level clouds increase west and central ahead of
approaching trough from system over the Plains and temps likely
level off or rise overnight. Out east, clearing will occur with
light ese winds developing and the Canadian model indicates drier,
cooler air getting pulled in from Ontario. Went on the colder end of
temp guidance over the far eastern counties where min temps should
drop into the single digits, perhaps into the single digits blo zero
for the se half of Luce County.
Saturday, model soundings show the column moistening up with
increasing WAA isentropic lift across the area so there could be a
dusting of light snow/flurries mainly in the morning over the west
half. Some WAA mid-clouds will also work into the eastern cwa in the
afternoon. Despite the increase in WAA clouds across the area, there
will also be minimal warming in a ese flow with max temps generally
rising into the mid to upper 20s.
.LONG TERM...(Saturday night through Friday)
Issued at 258 PM EST FRI JAN 29 2021
Overall, the long term period starts warm and mostly dry, but more
active weather is expected late next week. A vertically stacked low
over Missouri at 00z Sunday will track east on Sunday then transfer
to the east coast on Monday. Weak warm air advection and associated
isentropic lift northeast of this low could squeeze out a couple
hundreths of QPF as light snow along the MI/WI border by Sunday
morning. A dry layer near 850 mb is the primary inhibiting factor
for more widespread light snow.
A more amplified upper level flow regime impacts our CWA next week
with ridging expected over the Great Lakes region Monday night
through Thursday. As a result, another period of much above normal
temperatures and generally dry weather is expected across the U.P.
early to mid next week. NBM guidance indicates high temperatures
near 32F Monday-Thursday ahead of a cold front late Thursday/early
Friday.
A western trough enters the plains on Wednesday resulting in surface
low development across the Central Plains. This low is expected to
track northeast into the Great Lakes region Thursday into Friday.
Warm air advection precipitation could begin as early as Wednesday
night, but more substantial synoptic scale precipitation is expected
on Thursday into Friday. Ensemble guidance indicates the low will
track across the U.P. implying more substantial impacts for western
zones, but overall confidence is low. NBM guidance indicates about 1
inch of QPF across the U.P. falling as wet snow, cold rain, or a mix
of both. A much colder air mass behind the low should allow synoptic
precipitation to transition to lake effect snow for Friday into
Saturday.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1022 PM EST FRI JAN 29 2021
VFR conditions will continue into Sat morning at all terminals. WAA
mid-clouds will move in later tonight ahead of a system moving
through the Plains. MVFR clouds will move in Saturday morning at all
sites.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 238 PM EST FRI JAN 29 2021
With a ridge of high pressure moving over the lake today, winds will
remain on the lighter side. As the high shifts east tonight, E to SE
winds will increase to around 20 knots west and north central late
tonight, before increasing to 20 to 25 knots across the lake
Saturday afternoon. Could be some gusts approaching 30 knots west
half Sat afternoon. Easterly winds will remain around 20 knots
through Saturday night and then generally fall blo 20 knots on
Sunday as a system passes to the south through the Ohio River Valley
on Sunday afternoon. Beyond Sunday, high pressure will remain over
the lake through the middle of the week, with light winds
prevailing. E-NE winds will likely increase toward gales late next
week with the expected approach of system from the central Plains.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...EK
AVIATION...07
MARINE...Voss
Area Forecast Discussion
National Weather Service Pocatello ID
135 PM MST Fri Jan 29 2021
.SHORT TERM...Tonight through Sunday night. Early afternoon
satellite imagery was showing a split upper through moving onshore
with the drier looking NRN branch advancing through
Washington/Oregon and the more dynamic SRN branch pushing east
through SRN California. The trough axis and associated instability
are expected to work from west to east across SRN Idaho late this
afternoon and evening promoting an enhanced band of rain and snow
showers across the area. The trough clears the Wyoming border early
Saturday morning with a drier west flow trailing across the region.
We do expect one last punch of snowfall across the mountains this
evening with the passing trough and thus have extended to current
hazards (Warnings and Advisories) until 10 PM. We should see drying
across the west later this evening and overnight as the storm
activity transitions into the ERN mountains. Accumulations run up
into Advisory levels at higher elevations across the ERN mountains
overnight and thus have blanketed the region with a Winter Weather
Advisory through Saturday morning. A ridge of higher pressure begins
to build across Idaho Saturday afternoon and night as the next
Pacific storm system advances into the NW coastal waters. With the
ridge overhead Sunday morning we might see areas of freezing fog and
low clouds (stratus) within the Snake River Plain. Little change is
noted in the overall pattern through Sunday night as several
disturbances cycle about the low. That should change sometime
Monday/Monday night (more on that below). Seasonable temperatures
should prevail through the forecast period. Huston
.LONG TERM...Monday through next Friday. Models develop upper
troughing off the Pacific coast and deepen it into WA/OR/CA by
Tuesday. The moisture ahead of the trough should begin to impact the
Central Mountains late Monday night. Moisture is expected to spread
to most of the forecast area by Tuesday. Both the GFS and ECMWF cut
off an upper low over UT/AZ on Wednesday, though the GFS is still
about 12 hours faster than the the ECMWF with the track of the low.
Ensemble clusters indeed show variance in the position of the upper
trough with the members favoring their deterministic counterparts.
One final system impacting the region next week is a reinforcing
upper trough moving in from the northwest Thursday night through
Friday per the GFS/EC. The Canadian model also shows this feature,
but brings it to Idaho about 24 hours later than the GFS/EC.
Hinsberger
&&
.AVIATION...A moist southwesterly flow will continue through this
evening. KSUN is still getting upslope conditions contributing to
the reduced ceiling/visibility. KPIH and KBYI will be strongly
downsloped again today until the surface cold front passes through
later this evening. The front may produce a quick burst of
snowshowers. HRRR forecast reflectivity is indicating strong
convection along the front--possibly generating some thunder. NBM
guidance is keeping some MVFR ceilings in behind the cold front,
though it`s less likely at KDIJ and KSUN. Hinsberger
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 10 AM MST Saturday for IDZ064.
Winter Storm Warning until 10 PM MST this evening for IDZ066-067-069-
073>075.
Winter Weather Advisory until 10 PM MST this evening for IDZ052-068-
072.
Winter Weather Advisory from 10 PM this evening to 10 AM MST
Saturday for IDZ060>063-065-066.
&&
$$
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
700 PM EST Fri Jan 29 2021
.DISCUSSION...
Late afternoon analysis has upper level ridging stretching north
over the nation`s mid-section...with an axis along the Mississippi
River Valley. Surface high pressure centered in the upper Great
Lakes region sprawls down into the Gulf of Mexico. The RAP model
slides these features into the eastern states by late Sat. A
stable and generally dry air mass prevails across the area.
However the boundary flow shifts from light northeast tonight to
east then southeasterly during Sat. This will allow temperatures
to warm and also provide a subtle increase in moisture...just
enough for a few to scattered clouds. Tonight will again be on the
chilly side but not as low as last night. Patchy frost will be
possible with the most likely locations in the north.
&&
.AVIATION...
30/00Z. VFR. SKC gives way to FEW-SCT CU/CI AFT 14-15Z. Light NE
winds become E then SE to S Sat AOB 10KT.
&&
.MARINE...
High pressure slides across the eastern US and out over the
Atlantic during the weekend with winds slowly veering...at 15
knots or less. The high pressure moves away Sun night as a cold
front approaches with showers and a few thunderstorms. Winds shift
and increase...up to 20 knots...as high pressure builds in Mon.
&&
.Preliminary Point Temps/PoPs...
TPA 49 71 58 74 / 0 0 0 10
FMY 51 75 59 76 / 0 0 0 0
GIF 46 73 54 77 / 0 0 0 0
SRQ 49 73 58 75 / 0 0 0 10
BKV 40 73 52 77 / 0 0 0 10
SPG 51 70 59 72 / 0 0 0 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
DISCUSSION/AVIATION/MARINE...09/Rude
UPPER AIR...04/Sobien
DECISION SUPPORT...04/Sobien