Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/24/20
See below for an aviation forecast discussion for the 00Z TAFs.
&&
.SHORT TERM...(This Evening through Monday Night)
Issued at 315 PM CST Sun Feb 23 2020
A storm system tracking southeast across the region Monday through
Tuesday will be the main forecast challenge in the short term. A dry
high pressure over the region this afternoon is producing breezy
northwesterly winds, mainly across the James River valley and points
east. The winds will diminish through this evening. Even with
increasing clouds later tonight, low temperatures should drop into
the teens and low 20s. Patchy to areas of fog will be possible
tonight, mainly in the James River valley.
An area of low pressure and upper level trough will move into the
western Dakotas on Monday with light pcpn possible in the
northwest portion of the CWA. Am concerned with the dry easterly
flow keeping a good portion of the CWA dry until Monday afternoon.
NAM/GFS buffer soundings for the Aberdeen area suggests dry
conditions until 3Z Tuesday. Accumulating snow in the Mobridge
area could be delayed until early afternoon if dry layer between
850-700 mb in the NAM is correct. Saturation looks best after 0Z
Tuesday, mainly west of the James River Valley. Snowfall amounts
of one to three inches appears likely, especially along the
Missouri River where isolated 4 inch amounts could be possible.
With the accumulating snowfall occurring Monday night into
Tuesday, will hold off on issuing a winter weather advisory. Half
km winds of 25 to 35 knot late Monday night into Tuesday morning
could cause patchy to areas of blowing and drifting snow. Of note,
the 18Z is slowing down the progression of the storm, with snow
moving into north central SD during the mid to late afternoon
hours on Monday. A narrow band of snow does appear possible with
this system. The latest models suggest the band will set-up in ND,
and perhaps as far south as northeast SD. Higher snowfall amounts
will be possible with this band.
.LONG TERM...(Tuesday through Sunday)
Issued at 315 PM CST Sun Feb 23 2020
Surface high pressure will settle in over the area Tuesday night,
and looks to be the dominant feature through Friday night. This will
keep somewhat cooler air over the region Wednesday and Thursday,
with high temperatures in the teens and 20s. As the high then exits
to the east, will see WAA develop as the region becomes situated
between the high and a low pressure trough to the west. High
temperatures will range from the upper teens east to the mid 30s
west on Friday, then will be in the 30s and 40s Saturday and Sunday.
Overnight lows will generally be in the single digits and teens
through much of the period, with the exception of Saturday night
when temperatures will only fall into the lower to mid 20s. Cannot
rule out a few periods of light precipitation during the period, but
there is no model agreement on location or timing and any impacts
would be minimal, therefore will keep conditions dry for now.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 547 PM CST Sun Feb 23 2020
Looks as though prevailing VFR conditions are going to erode into
some MVFR/IFR conditions within the next 12 to 24 hours.
Prior to the onset of the next low pressure system on Monday,
there could be some sub-VFR fog/visbies developing later this
evening in the James River valley toward 06Z at KABR; between 06Z
and 15Z in the James River valley and up on the Prairie Coteau at
KABR and KATY.
When the low pressure system works through the region Monday and
Monday night, expect widespread coverage of lower (MVFR/IFR) cigs
and reduced (MVFR/IFR) visbies in snow across central South
Dakota (KPIR/KMBG), with intermittent sub-VFR cigs at KABR/KATY.
Precipitation may also extend east as far as the KABR/KATY
terminals during this next precipitation event, but probably not
until some point beyond the current 24 hour TAF valid period.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Dorn
SHORT TERM...SD
LONG TERM...Parkin
AVIATION...Dorn
Area Forecast Discussion
National Weather Service Dodge City KS
504 PM CST Sun Feb 23 2020
...Updated Aviation Discussion...
.SHORT TERM...(This evening through Monday)
Issued at 220 PM CST Sun Feb 23 2020
A significant precipitation event is still on track to affect much
of southwest, central, and south central Kansas this evening into
the overnight hours. Latest satellite imagery showed cumulus
expanding in coverage across northeastern New Mexico into adjacent
Texas Panhandle as the mid level cold pool aloft was moving slowly
east. Temperatures warmed into the upper 60s to around 70 degrees
across portions of the eastern Panhandles with 60 degree isotherm as
far north as Dodge City at 19Z. The HRRR and RAP did a very good job
with the 2-meter temperature forecast, whereas the NAM12 performed
quite poorly in this department. The cold outlier NAM12 solution is
just not trusted with this storm system, and this goes for tonight
as well, and as such the snow amounts have been lowered tonight.
Total precipitation, however, still looks very good with an axis of
1.5" plus from Dodge City east into central/south central Kansas.
As far as the severe weather risk goes, since it is warmer like the
HRRR and RAP, more instability was developing into far southwest
kansas. As the cold pool aloft continues to approach southwest
Kansas by early this evening, low level convergence will also
continue to increase, which will help dewpoints continue to increase
to the 48-50F range as far north as Seward and Meade County. This is
the portion of our forecast area we are most concerned with for any
severe weather. Given the time of year and development of SBCAPE up
to 600 to 800 J/kg, the only real severe weather risk would be large
hail up to the size of about a quarter or so. There will be enough
low level shear to support low level mesocyclogenesis, perhaps
supporting a weak, brief tornado, which is something that will have
to be watched along the Oklahoma border. Once the convective portion
of the event winds down later this evening, the comma-head structure
of the storm will take shape overnight as the precipitation becomes
more stratiform in nature. It still appears this deformation zone
will be focused along the Arkansas River valley in the 06-12Z time
frame overnight/early Monday morning.
.LONG TERM...(Monday night through Sunday)
Issued at 220 PM CST Sun Feb 23 2020
The next upstream system will bring strong northwest winds and
another round of (light) precipitation Monday Night and again on
Tuesday. This system now appears to be digging south a little bit
farther west across Kansas, and as such we will maintain some 20-30
POPs through Tuesday. The first of the two light rounds Monday Night
will start off as a cold rain but then change to a wet snow some
time around midnight Monday Night. 850mb cold advection ramps up
late Tuesday into Tuesday Night as the next lobe of upper level
energy swings south into Kansas. The mid levels will be very cold
late Tuesday into Tuesday Night, so any little bit of moisture will
likely result in some light snow late Tuesday/Tuesday Evening.
Another (much weaker) northwest flow wave will reinforce the
longwave trough pattern late Thursday-Thursday Night, which will
really do nothing more than delay any substantial warm up that we
otherwise would be seeing as overall heights increase out west
across the Great Basin region. By Friday and especially the upcoming
weekend, we will see temperatures warming back into the 50s and
eventually 60s for daytime highs.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 437 PM CST Sun Feb 23 2020
Mainly VFR conditions for all TAF sites except for MVFR visibility
for HYS due to light rain falling on station as depicted on radar.
Expect showers and isolated thunderstorms to push into far
southern Kansas out of the Oklahoma panhandle giving way to SHRA
and VCTS first at LBL then DDC and GCK by 01Z with ongoing rain
for HYS not expecting thunderstorms to push that far north due to
the colder air sinking in from northwest and north central Kansas.
This will turn to a wintery mix for all locations by 05-11Z with
MVFR ceilings expected as low stratus pushes across along the
frontal boundary turning winds out of the northwest gusting up to
25-30kts. Improving skies after 12Z as stratus burns off with
daytime heating before gusty winds push in after 20-21Z for GCK
and HYS before increasing for DDC and LBL after the end of the
period due to being along the backside of the low pressure system
making its way out of the CWA to the east and southeast.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 33 52 28 38 / 100 40 30 10
GCK 30 50 25 37 / 100 10 20 10
EHA 30 54 26 38 / 80 10 20 10
LBL 31 53 26 40 / 90 10 30 10
HYS 33 53 29 37 / 80 30 30 40
P28 40 56 33 45 / 100 70 30 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Lowe
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
938 PM CST Sun Feb 23 2020
.UPDATE...
Evening AMDAR Aircraft soundings out of SAT and AUS continue to show
a stout capping inversion around 800mb. This cap is the likely reason
that the evening high resolution model suite from SPC and multiple
runs of the HRRR have backed way off on precipitation along the front
late tonight and into tomorrow morning. Forecast soundings do show
that cap eroding gradually later tonight so have only pulled back
PoPs by 10 to 20 percent across parts of South Central Texas. In
addition, with the cap in place the likelihood of a thunderstorm
being produced continues to decrease, but can`t completely rule out
an isolated rumble of thunder, especially across areas east of I-35.
For the most part the forecast is on track though with the front
arriving overnight and most of the precipitation clearing the area
by sunrise. Skies will clear tomorrow with a northwest wind behind
the Pacific front, but temperatures won`t turn cooler until the next
front arrives Tuesday.
&&
.PREV DISCUSSION... /ISSUED 534 PM CST Sun Feb 23 2020/
AVIATION...
VFR conditions have broken out across all of South Central Texas this
afternoon. While DRT will be VFR through the period with the Pacific
front arriving by 06z, the I-35 terminals will see deteriorating
ceilings through the evening. The front is currently along a KPEQ
(Pecos) to KLBB (Lubbock) to KAMA (Amarillo) line and should be to
the I-35 corridor by 15z Monday morning. Ahead of the front MVFR
cigs will begin around 04z with IFR and possibly a few pockets of
LIFR between 08z and 12z. Light right is already showing up on area
radars across the Hill Country with showers expected overnight along
the I-35 corridor as the front approaches. An isolated thunderstorm
is possible, especially around AUS, but should the capping inversion
hold the majority of the precipitation should be rain showers so have
taken out the mention of thunder from the AUS TAF for now due to the
low confidence forecast. Winds along the I-35 corridor will go from
south easterly this evening to west and northwest by 14z Monday
morning.
PREV DISCUSSION... /ISSUED 228 PM CST Sun Feb 23 2020/
SHORT TERM (Tonight through Monday Night)...
Aircraft soundings this afternoon from AUS and SAT indicate a strong
capping inversion around 850mb. Abundant stratocu is ongoing beneath
the cap, with the exception of the southwest CWA. The cap will be
key to convective chances later tonight ahead of a Pacific cold
front. While the core of the main forcing aloft will pass north of
the region, the tail end of the forcing will assist with weakening
of the cap just ahead of the cold front across portions of the Hill
Country and I-35 corridor. 12Z GFS as well as latest runs of the
HRRR and NMM WRF soundings indicate a complete erosion of the cap
between 9PM and 3AM, allowing deeper convection to develop along and
ahead of the front across portions of the Hill Country and I-35
corridor, north of San Antonio. 12Z 3KM NAM, ARW WRF, and Texas Tech
WRF soundings do weaken the cap during the same time, but not as
fast, leading to mainly weak showers ahead of the front. The
majority of SREF members are indicating precip ahead of the front,
along and north of U.S. 90, so we have raised PoPs slightly for
showers in this forecast package. However, due to the uncertainty
with the cap and deeper convection being able to be realized we will
keep thunder chances at 20%.
Drier northwest flow and clearing skies will develop behind the cold
front Monday morning. The Pacific nature of the front and
downsloping flow will actually allow for warmer afternoon high
temperatures tomorrow compared to today. Many areas will reach the
mid 70s to near 80. Closer to the Rio Grande, elevated fire weather
conditions are forecast where low RH values in the teens combined
with occasional wind gusts near 20mph occur. Clear and cool
conditions are forecast Monday night.
LONG TERM (Tuesday through Sunday)...
An upper level low will move across the Central Plains Tuesday and
send a cold front through South Central Texas. Winds will become
northerly bringing cooler, drier air. Cold advection will continue
through Wednesday when the pressure gradient will intensify and winds
will be breezy. High temperatures Wednesday will be mostly in the
50s. Thursday morning low temperatures will drop below freezing
everywhere except the Rio Grande Plains and the Winter Garden region.
Lows in the Hill Country and Edwards Plateau will be in the middle
20s. The dry air and breezy winds will make for elevated to near
critical fire weather conditions Wednesday afternoon. Surface high
pressure will meander around the eastern half of Texas during the
second half of the week with no dominant flow regime. This will mean
dry weather and gradual warming through the end of the week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 59 74 47 65 38 / 40 10 0 0 0
Austin Bergstrom Intl Airport 58 75 41 67 38 / 50 10 0 0 -
New Braunfels Muni Airport 58 76 45 69 38 / 50 10 0 0 -
Burnet Muni Airport 53 71 42 62 34 / 30 0 0 0 0
Del Rio Intl Airport 54 79 46 71 39 / 10 0 0 0 0
Georgetown Muni Airport 57 73 41 63 36 / 40 - 0 0 -
Hondo Muni Airport 56 78 43 72 38 / 30 0 0 0 0
San Marcos Muni Airport 59 75 43 68 38 / 50 10 0 0 -
La Grange - Fayette Regional 61 75 47 69 40 / 60 30 0 0 -
San Antonio Intl Airport 59 77 46 69 40 / 40 10 0 0 -
Stinson Muni Airport 60 78 47 72 41 / 40 10 0 0 -
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...Treadway
Long-Term...Hampshire
Area Forecast Discussion
National Weather Service Grand Forks ND
948 PM CST Sun Feb 23 2020
.UPDATE...
Issued at 944 PM CST Sun Feb 23 2020
Mainly clear over the area at 03z. West winds are diminishing as
expected. Did change pops in our far west and southwest after
coord with BIS as 00z NAM and latest short term models still
indicate a farther south/west band of snow Monday. The narrow zone
of frontogenetical forcing that forms Monday and gives the risk of
a higher snowfall band now looks safely south/west of the fcst
area more so between BIS/JMS. Thus lowered pops further in DVL
basin and kept highest pops more so BIS/JMS.
Main challenge will be to see if idea of low clouds and fog
development in NW/WC MN occurs starting 05z/06z. It would be
radiational as skies mainly clear and winds light. Confidence in
development and expanse of this overnight into Mon AM over MN fcst
area is quite low.
UPDATE Issued at 652 PM CST Sun Feb 23 2020
Biggest chance was done to add fog to areas east of the Red River.
Strong signal in short range ensembles that fog will form 04-05z
time period over WC MN and spread north. Winds will go near calm
this evening, so radiational fog situation seems plausible. But
still some doubts as had west wind all day, but trends on
ensembles and aviation HRRR hard to ignore.
Also some chat with ABR and looking at latest RUC/HRRR and 18Z GFS
would indicate a less chance for snow into our SW fcst area. RUC
still has that narrow band of a bit heavier snow (1-2 inches)
extending southeast but that area has been shifting south and it
now Valley City to maybe Lisbon. Indications are strong that
Fargo, Wahpeton, Devils Lake north and east will be dry.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 331 PM CST Sun Feb 23 2020
Quiet weather this evening with decreasing winds and mostly clear
skies. Mild temps once again this afternoon despite the weak cold
front passage, helped by lots of sunshine. Expect cooler lows if we
remain clear, with surface high migrating over our CWA and
light/variable winds. We may see some single digits at colder spots,
but event that would be near seasonal normals.
Main focus will be on the closed trough expected to migrate from
Montana across western ND and eventually into South Dakota. Main
mid/upper low track is still west of our CWA limiting larger scale
synoptic forcing/moisture advection. Considering this, consensus
most likely amounts will be less than 1" through Monday evening.
At the same time there is still a signal for a mesoscale band
associated with brief deformation east of the 700MB low center, and
positive frontogentic forcing within axis of WAA nosing into the
southern Devils Lake Basin and southeast ND. Soundings tend to show
a persistent dry layer that may need to be overcome/saturated and
there isn`t any instability of note. HREF and NBM both show a low
probability signal though for 4" amounts (generally 20% or less)
where this band may form and track in our western CWA maybe as far
east as the souther Red River Valley, and most deterministic models
are trying to resolve it (but varying in location). Due to the brief
nature of this deformation/frontogensis, and lack of instability it
may be more likely to achieve rates of 0.25-0.5" per hour at most
(matching HREF mean). Still, with morning rush and at least
"potential" for 2" or greater over a narrow/localized area we
decided to introduce mention to HWO and graphics for minor travel
impacts.
Luckily winds are not going to be too strong and will be
slower to increase (later Monday night). Any blowing/drifting
snow impacts Monday night/early Tuesday morning will likely
depend on what movable/blowable snow is in place, and right now
peak gusts will generally be in the 25-35 mph range (likely not
high enough to break up existing snow pack).
.LONG TERM...(Tuesday through Sunday)
Issued at 331 PM CST Sun Feb 23 2020
Little impactful weather is expected in the long term period as
northwest flow aloft shunts moisture away from the region. Closer to
seasonable temperatures are expected through the work week
before another warming trend ensues late in the period.
As an upper low moves out of the central Mississippi Valley into the
Great Lakes region, northwest flow aloft will dominate through the
work week before riding aloft develops out of the west. This will
prevent return flow of any appreciable moisture return from the GoM.
Within this flow, there is expected to be one of more passing quick
shortwaves. These clippers may acquire moisture from the Pacific
source and produce a chance for light snow, although spread in
ensemble and lack of appreciable forcing signal negates its
inclusion into the forecast. Thus the forecast reflects mostly dry
conditions Tuesday through Sunday.
With northwest flow aloft and troughing to the east, temperatures
are expected to become more seasonable with highs generally in the
teens above zero and lows in the single digits below zero. Later in
the period towards the weekend, ridging aloft develops increasing
the chance for another warming trend with highs near or above
freezing.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 602 PM CST Sun Feb 23 2020
Model blends all indicate the potential for low clouds and fog to
form just east of the Red River in the 06z-14z period. Winds will
go calm this evening allowing for radiational fog formation and
then low clouds. Models are bullish on this and in good agreement
but west flow at the sfc this aftn not advecting low level moist
air in, so should be radiational fog driven. With that, high
variability location to location with impacts for MN TAF sites.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Riddle
SHORT TERM...DJR
LONG TERM...CJ
AVIATION...Riddle
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
515 PM CST Sun Feb 23 2020
...AVIATION UPDATE...
.SHORT TERM...(This evening through Monday)
Issued at 257 PM CST Sun Feb 23 2020
Closed low over the four corners region this morning continues to
track east and will be the impetus of some potential precipitation
for our north central Kansas counties tonight. Latest runs of the
NAM/HRRR indicate that the surface low is still on track to travel
east near the Kansas/Oklahoma border, and probably siding on the
Oklahoma side as the NAM has been trending slower and farther south
with this track and the HRRR and RAP have consistently placed the
surface low on the Oklahoma side and slower to arrive still than the
NAM. This all points to less precipitation expected for our north
central KS counties, as has been clearly the trend over the past
couple of days, and I concur with this direction from the previous
forecast. Precipitation amounts continue to look like, and perhaps
could start as early as late this afternoon into the evening. The
Nebraska side of our CWA still looks pretty much bone dry tonight as
has been the trend over the past few model runs.
Although latest runs of the HRRR and RAP indicate that precipitation
will likely be all rain tonight, I do think that dynamic cooling
could very well end our precip with a little bit of slushy wet snow
toward the end of precipitation, especially along the
west/northwest fringe of the precipitation shield.
Almost as soon as this system exits, we have yet another chance of
some precipitation coming primarily in the Monday night through
Tuesday frame as another wave dives in from the northwest.
.LONG TERM...(Monday night through Sunday)
Issued at 257 PM CST Sun Feb 23 2020
A period of snow showers is expected, primarily for Monday night
into Tuesday evening as a quick-moving wave comes through from the
northwest. Overall, qpf/snowfall is backed off in model world and
WPC has trended less with snow amounts a bit. Generally one to
two inches is possible in the northeast half of the CWA, with
highest amounts generally northeast.
By Wednesday, we will be within predominantly northwest flow between
the mean trough axis over the Ohio and Tennessee Valleys and the
broad ridge over the western United States. Going with a blend of
GFS/ECMWF ensemble blend in the long term. There still appears to be
some agreement between the GFS and ECMWF that a weak perturbation
will swing through Thursday night into Friday. It appears that there
will be at least some shot at some sprinkles/flurries in this time
frame, but models are also in agreement that any precipitation would
be rather light.
Still looks like a moderating scenario heading toward the weekend as
the ridge is encouraged to translate east by an eastern Pacific
trough and the exit of the eastern CONUS trough. However, tends in
both the ECMWF and GFS ensembles indicate a slower dislodging of
colder air through Friday. Still looks like a relatively mild
weekend for this time of year, and there is consensus in ensembles
that the weekend will be dry.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday)
Issued at 509 PM CST Sun Feb 23 2020
An area of low pressure moving over OK will keep mid and high
level clouds over the area. Winds will gradually shift from NE to
W as the low moves east into AR. VFR expected through the period.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...Heinlein
LONG TERM...Heinlein
AVIATION...Beda
Area Forecast Discussion
National Weather Service North Platte NE
612 PM CST Sun Feb 23 2020
.SHORT TERM...(This evening through Monday night)
Issued at 259 PM CST Sun Feb 23 2020
Concerns in the near-term revolve around the potential for rain/snow
and snow chances Monday into Tuesday with the next disturbance
moving into the area. The period begins with relatively zonal flow
aloft as a compact h5 cut-off trough currently ejecting onto the
Southern Plains moves into southeast Colorado and parts of southwest
Kansas into the OK/TX Panhandles. This feature has been well
advertised for a few days now with concerns that the area could see
impacts from its northern fringes of precipitation. Light echos have
been prevalent on radar much of the daytime as modest fgen is thrown
north from the main trough. This fgen has generally weakened as it
lifts now, however, has managed to produce a few pockets of perhaps
sprinkles across southwest Nebraska. Inherited forecast contained
"Slight Chance" and "Chance" PoPs across these areas but these were
removed owing to the abundance of dry air in the lowest 2 km. Both
the RAP and HRRR were quick to pick up on this and thus supported
the decision to remove and replace with just a mention of sprinkles.
Dew point depressions of nearly 40 degrees Fahrenheit and cloud
bases of 9k feet AGL or greater back up this thought. Expect these
light echoes and possible sprinkles to linger for areas along and
south of Interstate 80 through the evening before moving off the
south and east, following the stronger mid-level fgen bands. Weak
surface high pressure will approach from the north late tonight with
a strengthening low pressure further south towards the KS/OK border.
Lows tonight will fall into the 20s to near 30 in proximity to the
Pine Ridge.
Attention quickly turns to the quick approaching shortwave trough
moving out of the Pacific Northwest and onto the Central Plains
during the day on Monday. Biggest forecast-to-forecast change has
been to slow the arrival of precipitation to the area as strongest
height falls and vorticity advection look to occur post-sunrise on
Monday. Lee-cyclogenesis will begin across western South Dakota
during the morning hours, leading to increasing southerly flow across
much of western Nebraska. As this low develops and treks east along
Interstate 90, an attendant surface cold front will sweep through
the region from west to east. It`s this feature and associated lift
coincident with it that`ll lead to increasing PoPs through the
morning hours into the afternoon. These PoPs will be greatest for
areas north of Interstate 80 through Monday evening. Daytime highs
will climb into the upper 30s to 40s, with thoughts that any
precipitation should be rain or a rain/wet snow mix. Dry air at the
surface will also need to be overcome as this system isn`t bringing
much moisture with it and residual dry air from Sunday will remain
in place. General thoughts are little to no QPF is expected during
the day on Monday. Winds behind this frontal boundary will increase
out of the west with gusts as high as 35 mph for portions of the
eastern Panhandle and 30 mph or less for further east. Elevated
winds will continue into Tuesday as h85 flow remains elevated with
30 to 40 knots of flow through the event. The approaching trough
will begin cutting off immediately upstream and with this occurring
will slow its progression Monday evening into Tuesday, becoming
centered over western Nebraska by early Tuesday morning. Strong
isentropic ascent, particularly on the 290-295K surfaces, along with
peaking differential vorticity advection will lead to increasing
precipitation towards sunrise on Tuesday. By this time, temperatures
will be well cold enough to support all snow across the region as
h85 temperatures approach -8 degrees C and h7 temperatures
approaching -20. The main h5 cutoff will have shifted south and east
of the area by late morning Tuesday, with subsidence behind the
departing wave and downglide across the lowest isentropic surfaces.
This should bring a quick end to precipitation through the afternoon
and into the evening. Current thinking is the heaviest precipitation
will be confined to areas north of Highway 2 with generally 1-3" of
snowfall expected and localized amounts closer to 4" possible. Did
discuss potential for Winter Weather Advisory with neighbors
considering expected snow totals and strong winds, but opted to
defer to later forecasts for now given lingering uncertainties with
where heaviest snowfall occurs. Tuesday will be well below-normal
for temperatures with highs in the 20s and 30s and lows in the
single digits to teens. Combined with strong winds, feels-like
temperatures will remain in the single digits to teens all day
making it feel very raw for late February.
.LONG TERM...(Tuesday through Sunday)
Issued at 259 PM CST Sun Feb 23 2020
Beginning 12z Wednesday. The extended period begins with highly
amplified northwesterly flow as the area is caught between the
departing trough and developing ridge along the west coast. Both the
ECMWF and GFS advertise a weak clipper-like system moving through
the area sometime in the Thursday/Friday timeframe. Both model
outputs are similar in thinking with respect to this potential
disturbance, although they differ on timing by 6 to 12 hours.
Because of this, opted to leave the forecast as is which has a small
coverage area of "Slight Chance" PoPs across north central Nebraska
Thursday. That appears to be the only blemish on an otherwise dry
forecast as the aforementioned ridging pushes eastward onto the
Plains by the weekend. This will allow temperatures to climb
Wednesday through Friday from the 20s/30s to 30s/40s. Then, as the
main ridging arrives overhead by Saturday, temperatures will jump
back into the 40s/50s with potential for some 60s on Sunday and dry
conditions. For the start of next week, another stout trough will
move onshore and approach the region in the Monday/Tuesday time
frame. Some uncertainty remains with where the greatest impacts will
be seen from this system as the GFS and ECMWF have vastly different
evolutions. Either way, be mindful of potentially active weather for
next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 608 PM CST Sun Feb 23 2020
VFR conditions will rule through noontime Monday. Mid and high
clouds will prevail with light winds. A cold front will move into
the area Monday afternoon with winds shifting to the northwest
with gusts up to 25 kt. In addition some scattered light rain or
snow will be possible. An area of MVFR ceilings will accompany the
front across northern portions of Nebraska including the KVTN
terminal.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Jurgensen
LONG TERM...Jurgensen
AVIATION...Taylor
Area Forecast Discussion
National Weather Service Marquette MI
742 PM EST Sun Feb 23 2020
.SHORT TERM...(This evening through Monday)
Issued at 340 PM EST SUN FEB 23 2020
Water vapor imagery and RAP analysis show a rather vigorous
shortwave moving across Lake Superior. Despite its strength, sunny
skies have prevailed across the fcst area today after some thin
stratus quickly exited/dissipated this morning. Under the sunny
skies, it`s been another warm Feb aftn across the fcst area. Similar
to yesterday, temps have again pushed above 50F at some locations
across the w half of Upper MI. SSW wind off Lake MI is again keeping
the e cooler. Cold front associated with the shortwave is currently
moving across central Upper MI. Postfrontal winds are fairly
strong/gusty as expected. Winds across western Upper MI are gusting
above 30mph at many locations with winds across the Keweenaw higher.
KCMX has had peak gusts btwn 44 and 51mph over the last couple of
hrs.
Cold front will clear the fcst area over the next several hrs. With
incoming pres rises around 2mb/3hr, modest CAA and waning solar
heating, winds will remain fairly strong/gusty over the w. Gustiness
will spread eastward with fropa, though cooler conditions over the e
as well as the start of boundary layer cooling with setting sun will
keep winds quite a bit lower than over the w. Over the Keweenaw,
expect gusts to around 45mph over the next few hrs as lingering
daytime heating and caa support deeper mixing to winds of 40-45kt.
Upstream, a narrow band of low clouds is streaking se into northern
MN. With the setting sun and diminished mixing, will probably see
these low clouds expand some as they push into the fcst area this
evening. With 850mb temps only falling to -5 to -8C across Lake
Superior, lake effect pcpn will not be a concern tonight. Min temps
will be in the 20s.
High pres ridge will build into the area from the nw on Mon,
resulting in nw winds veering northerly during the aftn. Fcst
soundings, particularly the NAM, indicate quite a bit of low-level
moisture and thus more clouds Mon. Other than the band of low clouds
dropping se thru northern MN, have to go quite far to the nw to get
into more expansive cloud cover. Low-level flow should advect this
moisture toward the area, but low-level flow will also become more
anticyclonic on Mon. In the end, painted a partly to mostly cloudy
sky across the area. High temps will fall back closer to normal, but
still above normal for late Feb, ranging from the lower 30s near
Lake Superior to about 40F far s central.
.LONG TERM...(Monday night through Sunday)
Issued at 338 PM EST SUN FEB 23 2020
As the area begins to feel the influence of the developing low
pressure system in the Mississippi Valley, winds will veer to NE
Monday night. under 850 mb temps of about -7 C at 06z Tuesday,
dropping to about -9 C by 12z, the upslope component of this wind
along with lake moisture from the still mostly ice-free Lake
Superior could end up generating some freezing drizzle over the
higher terrain of the NE wind lake-effect belts. NAM and GFS
soundings show saturation that is somewhat marginal for precip - only
about 2500 to 3000 ft - but that`s ended up being enough several
times before recently. With very dry air just above about 3 kft (or
just about -8 C) this precip would almost certainly be FZDZ to
start, transitioning to a mix of snow showers and FZDZ during the
day Tuesday as temps aloft cool and deeper moisture slowly creeps
northward. Actual accumulations of snow or ice look minimal, but
given that the roads are mostly clear now from a couple days of
melting, and in some spots have had the salt washed clean by
meltwater, there could end up being slick spots on the roads for the
Tuesday morning commute. So this will need to be watched closely.
After that attention turns to what still looks like a significant
storm system developing over the Central Plains. Models continue to
struggle somewhat with the exact timing and locating of the phase
between a northern stream short wave diving southeastward through
the Plains and a vort max on the southern stream ejecting out of the
SW U.S. Contrary to yesterday, the trend in the models today has
been back east somewhat and thus towards less synoptic/system snow
for the U.P. This includes the GFS and the GEFS, which yesterday
were more amplified outliers. Rather than windshield-wiping any more
on POPs, mostly kept the chance to low-end likely POPs generated by
the NBM for now in case there end up being another shift back west.
Regardless of how much "system" snow the area ends up seeing,
prospects for a long duration of moderate to perhaps heavy lake-
effect snow are increasing for Wednesday night through Thursday
night. The GFS and EC are in good agreement that as another short
wave merges into the upper level low late Wednesday, an inverted
upper level trough develops to the west over Lake Superior which
allows moisture to remain deep as strong CAA occurs. The combination
of 850 mb temps in the -17 to -20 C range and saturation to, at a
minimum, 700 mb, should support plenty of LES for the N to NW wind
snow belts, especially on Thursday. Therefore, have increased POPs
to likely or higher in those areas at that time. Still too early to
talk about potential accumulations though, except to say that while
several inches looks possible, this will probably be a long duration
of on-and-off snow showers, and a fluffier snow more typical of lake-
effect, both points which should reduce the overall impact. That
system finally moves out somewhere around Friday. With high pressure
expected to build in behind it, next weekend right now looks dry
save for any lingering lake-effect snow showers over the eastern
U.P.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 738 PM EST SUN FEB 23 2020
Colder air moving in this evening in the wake of a frontal passage
will continue to result in gusty winds this evening with gusts to
25 kt at KIWD and to 30 for a few hrs at KCMX. Post frontal MVFR
cigs should also develop at KCMX/KIWD this evening and perhaps at
KSAW though downsloping may prevent a bkn or ovc cig from
developing. Winds will diminish during the night. As winds become
more n-ne Mon afternoon expect MVFR cigs to develop at KSAW as
well. &&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 340 PM EST SUN FEB 23 2020
Cold front is currently extending s across central Lake Superior.
Expect gales of 35-40kt to continue following the front as it exits
the lake over the next several hrs. Winds will then diminish to blo
gale force from w to e during the night tonight. Winds will diminish
further to blo 20kt on Mon. As low pres slowly lifts across the Ohio
Valley, Great Lakes and into Quebec Tue thru Thu, n to ne winds will
increase to at least 20-30kt. In fact, over central and eastern Lake
Superior, it is looking a little more likely that gales to 35-40kt
will occur late Wed night thru early Fri. Winds will then
gradually diminish from w to e during the day Fri.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Warning until 5 AM EST Monday for LSZ251-267.
Gale Warning until 4 AM EST Monday for LSZ243>250-264>266.
Gale Warning until midnight EST /11 PM CST/ tonight for
LSZ240>242-263.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...RJC
AVIATION...Voss
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Nashville TN
759 PM CST Sun Feb 23 2020
.UPDATE...
FOR EVENING DISCUSSION.
&&
.DISCUSSION...
Radar continues to show light echoes mainly south and west of
Nashville. Dew points continue to rise and the atmosphere has
undergone considerable moisture advection during the last 12
hours, but the layer below ~800 mb is largely dry and ceilings
remain VFR. The HRRR shows only light precipitation until closer
to 12Z. Hourly grids are holding up well thus far, so no forecast
changes are planned this evening. Will update the public forecast
shortly for wording only.
&&
.AVIATION...
00Z TAF DISCUSSION.
Light returns are showing up across the area on radar at this
time. Low levels are still dry so only a few light showers have
reached the ground at BNA and MQY. It will still take a few more
hours to moisten the low levels enough for cigs to fall below VFR.
Eventually cigs will drop to MVFR/IFR and possibly LIFR at CSV.
The probability of showers is high enough to mention through the
end of the taf cycle. There could even be a stray storm late
Monday afternoon at CKV but probability is not high enough to
include VCTS. Winds will be southerly through the taf forecast and
become gusty by Monday midday.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION......08
AVIATION........Reagan
AREA FORECAST DISCUSSION
National Weather Service Charleston WV
932 PM EST Sun Feb 23 2020
.SYNOPSIS...
High pressure exits tonight. Warm front lift north Monday.
Surface low pressure and associated cold front pass Wednesday.
&&
.NEAR TERM /UNTIL 9 AM MONDAY MORNING/...
As of 930 PM Sunday...
Adjusted minimum temperatures down at some of the higher
elevations based on guidance. Also adjusted dewpoint
temperatures for the next several hours to better represent the
current conditions. Sky cover was increased for parts of the
area for the next few hours to be more representative of current
satellite.
As of 143 PM Sunday...
Surface high pressure exits east tonight as a surface low pressure
located over western KY approaches from the west.
Models differ on the onset of QPF with the associated warm front.
The NAM model is the slower of synoptic models bringing the onset of
rain across the WV and KY border by 12Z Monday. Preferred the high
resolution RAP model which is even slower and weaker onset of
precipitation. Coded chance PoPs with by 12Z and likely PoPs
spreading from south to north by 18Z Monday. However, periods of
rainfall will continue into Tuesday afternoon. Expecting close to
0.50 inches of rain accumulations across the extreme southern
portions of the area, and around 0.25 inches elsewhere. Flash flood
guidance range from 1.5 to over 2 inches across the southern
coalfields, so flooding problems are not anticipated.
After sunset, temperatures will drop into the mid to upper 30s
across the lowlands, ranging into the upper 20s higher elevations.
It could be not as cold if cloudiness persist tonight, but skies are
expected to clear later this evening. There could be a brief period
of mixed precipitation along the mountains early Monday morning if
pcpn reaches the cold spots by this time, but chances are very
low.
&&
.SHORT TERM /9 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/...
As of 147 PM Sunday...
Short term period starts out with light rain across the CWA, with
an upper shortwave and surface low across the midwest. Temps Monday
night should remain rather steady, owing to a southerly flow across
the area. Much of Tuesday will dry out across the area as the
surface low lifts north. However, a stronger upper trough/closed low
will develop across the central U.S., and eventually trek northeast
into the Great lakes region by Wednesday, sweeping a cold front
across the area. Much colder temperatures, and gusty winds will
occur during this period, and will see a change over to snow area
wide by Wednesday night, with light accumulations possible mainly
across the higher terrain.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 148 PM Sunday...
Gusty winds and much colder conditions can be expected to start the
long term period, along with overall drier weather taking hold as
low continues to move off to the northeast. Another disturbance is
possible over the weekend, bringing a reinforcing shot of cold air,
and light precipitation.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
As of 625 PM Sunday...
Sites will continue to see VFR conditions for the beginning of
the period. Ceilings will begin to lower as the next system
moves in from the southwest. MVFR conditions in ceilings should
occur at the sites in the morning on Monday, starting from the
southwest and lowering toward the northwest over the day on
Monday. Some sites will see rain during this TAF period,
particularly CRW, HTS, and BKW. Visibilities may begin to
slightly lower as this rain moves in.
Winds will mostly be light and variable throughout the period.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z TUESDAY...
FORECAST CONFIDENCE: High.
ALTERNATE SCENARIOS: Timing of MVFR conditions could vary.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE MON
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11
EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 00Z TUESDAY...
IFR possible in rain Monday night through early Tuesday, and
then Wednesday and Thursday in rain and snow.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...None.
OH...None.
KY...None.
VA...None.
&&
$$
SYNOPSIS...ARJ/SL
NEAR TERM...ARJ/CG
SHORT TERM...SL
LONG TERM...SL
AVIATION...CG