Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/14/20
Area Forecast Discussion
National Weather Service Caribou ME
931 PM EDT Fri Mar 13 2020
.SYNOPSIS...
Low pressure will move east of the forecast area tonight. High
pressure will build toward the region later Saturday through
Sunday, then move east on Monday. A frontal system is expected
to move into the region on Tuesday. High pressure returns
Wednesday.
&&
.NEAR TERM /THROUGH SATURDAY/...
915 PM Update...The the Winter Weather Advisory was allowed to
expire. The St. John Valley came out the winner w/this latest
storm. The St. Agatha and Madawaska are received 10 and 12
inches of snow respectively. Less amounts as one travels east
and to the south. The NWS Office in Caribou measured 4.2 inches
of snow. Snow has come to an end as seen on the latest radar
loop. Some fog has developed this evening as winds have dropped
off significantly and llvl moisture remains. The thickest fog
is across the St. John Valley. The fog is expected to lift over
the next few hrs as winds start to pick up. Adjustments were
made to the hrly temps and snowfall amounts. Slight adjustment
to the winds to start them out lighter than previously expected.
The 18Z NAM and latest RAP had things handled well.
Previous Discussion...
The pressure gradient will remain very strong tomorrow between
the roughly 990 mb trough off to the north and a 1032 mb ridge
over the Ohio River Valley. Clearing and advection of cold air
aloft will lead to efficient mixing of winds to the surface
during the day Saturday, with gusts very close to wind advisory
criteria based on forecast soundings. Self-destruct
stratocumulus will develop and could slightly hinder fullest
mixing potential. Higher elevation sites could see gusts up to
around 50 mph, but most locations should peak around 45 mph.
Isolated snow showers are possible over higher terrain favored
by the upslope flow. Winds will diminish gradually during the
evening as a weak surface inversion begins to form. Blowing snow
will be possible across the far north where heavier
precipitation ends as snow, but coverage and intensity may be
limited by current above freezing temperatures.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
Cyclonic flow conts Sat night into Sun as low departs into the
Maritimes. In it`s wake stratocu wl continue ovr the north and west.
Cannot rule out a flurry or two over favored areas but does not
appear likely given dry airmass moving in.
Sfc high pressure wl be building twd the area out of Canada on Sun
night and with winds decoupling and skies clearing hv undercut
guidance by about 3-5 degrees for the deeper vlys in the North
Woods.
High builds offshore drg the day on Monday leaving sunny skies along
with light swrly winds in the aftn. After a cold start to the day
expect that highs wl rise to blo normal values with m/u20s expected
over the north and l/m30s for Downeast areas.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
High pressure builds off the coast and return flow wl spread pcpn
into the area on Tue, likely starting as snow across the north and a
rain/snow mix over central areas as well as rain along the coast.
Cold front quickly moves thru Tue night with temps on Wed dropping
down to near normal after an above normal day on Tue. A return to
high pressure will keep systems at bay on Thursday before an active
wx pattern returns next Friday.
&&
.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
NEAR TERM: IFR conditions will improve to VFR overnight. Low
level wind shear will be possible overnight as winds aloft shift
W and strengthen while surface winds decrease. Brief periods of
MVFR are possible across the north in isolated -SHSN.
SHORT TERM:
Sat night-Mon night...VFR at all terminals. KFVE may see MVFR
cigs Sat night before improving. NW winds 10-20kts Sat night/Sun
with gusts to 20kts. Light winds Mon morning becoming SW around
5kts.
Tue-Tue night...IFR due to cigs and rain/snow moving in Tue
morning increasing to MVFR/VFR Tue night at Downeast terminals.
S 10-20kts and gusty on Tue becoming W late Tue night.
Wed...Becoming VFR across the north. W 5-15kts.
&&
.MARINE...
NEAR TERM: Gales continue across most of the waters tonight
through the forecast period with a very brief break of a couple
hours as winds shift from south to west and increase again by
midnight. Competing swells will create choppy seas overnight and
into tomorrow along with maintaining wave heights over 6 feet.
Lengthy SCA conditions are expected over the intracoastal waters
after midnight tonight, when gales expire over these waters
only.
SHORT TERM: Gales drop off to strong SCA conditions Sat evening
and below SCA Sun morning. Seas also diminish to blo 5ft Sun
morning and remain below until increasing in southerly swell on
Tuesday before dropping again Wed. Gales will be possible again
on Tue.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...Gale Warning until midnight EDT tonight for ANZ052.
Gale Warning until 8 PM EDT Saturday for ANZ050-051.
&&
$$
Near Term...Hewitt
Area Forecast Discussion
National Weather Service Cheyenne WY
948 PM MDT Fri Mar 13 2020
.UPDATE...
Issued at 939 PM MDT Fri Mar 13 2020
We are sending out another update to expand the Freezing Fog
Advisory further east to Pine Bluffs overnight. Latest water vapor
loop was showing the potential vorticity anomaly continuing to
shift eastward with quite a bit of potential vorticity advection
taking place in the central Nebraska panhandle. In fact,
Scottsbluff has dropped to 1/4 mile in snow/blowing snow during
the last hour or so. As a result, they could pick up a total of 3
to 4 inches of snow before ending. The Pine Ridge could even
pickup a little more. Thus, the Winter Storm Warning still looks
valid for that area. Meanwhile, the dense fog will persist
especially along the Cheyenne Ridge where southerly flow will
persist through at least daybreak and perhaps through mid morning
Saturday. Overnight shift may need to expand the Dense Freezing
Fog Advisory further east into the Nebraska panhandle, due to
moist upslope flow.
UPDATE Issued at 825 PM MDT Fri Mar 13 2020
We are sending out a quick update to introduce freezing drizzle in
portions of the southern Nebraska panhandle.
Latest observations from Sidney was reporting freezing
rain/drizzle across that area during the past couple of hours.
In fact, webcams are showing some icing taking place on them.
Latest water vapor loop/IR imagery was showing a dry slot over
that region, but it appears to be filling in during the last 30
minutes. Regardless, it will most likely create slick conditions
in this region through midnight. Meanwhile, IR imagery was showing
some heavier bands of snow developing along and north of a Bayard
to Alliance line. We just had a spotter call in just north of
Bayard and reported low visibility and blowing snow in this
region. The latest Hi-Res models are showing this band of snow
exiting the panhandle by around midnight.
UPDATE Issued at 340 PM MDT Fri Mar 13 2020
Southeast upslope winds continuing this afternoon. Does not look
like they shift through the overnight hours. Latest CYS ASOS
reporting 1/4 mile in FZFG. Went ahead with a Freezing Fog
Advisory for central Laramie County...as well as the eastern
foothills as well as the Summit through 12Z Saturday. Updates have
been sent.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 220 PM MDT Fri Mar 13 2020
Forecast concerns deal with snow accumulations today through
Saturday morning.
Currently...Surface low pressure system over eastern Utah and
western Colorado this afternoon. Arctic boundary lays across South
Dakota into southern Montana. Southeasterly upsloping winds east
of the Laramie Range with over running mid level moisture from
the southwest low moving into the I-80 Corridor from the southern
Panhandle over to Evanston. Getting some banded snow being seen on
radar over Cheyenne at this time...but it is shifting north.
Latest HRRR and Hires guidance showing a band developing over the
northern Nebraska Panhandle late this afternoon...persisting
through at least midnight before shifting north of the CWA.
GFS...NAM and ECMWF all in good agreement with close to 1/2 inch
QPF over the northern Panhandle late this afternoon through 06Z.
NAM most bullish still at 3/4 inch. In an earlier
update...upgraded advisories to warnings for the northern half of
the Nebraska Panhandle.
Snow looks to taper off significantly after 12Z Saturday and we
may need to cancel the winter headlines earlier than what we have
in now. Later shifts can handle those issues.
.LONG TERM...(Saturday night through Friday)
Issued at 220 PM MDT Fri Mar 13 2020
By the end of the weekend, a broad upper level ridge will be
centered over the Central US as an upper level low positions
itself off the Pacific NW Coast. The progression of this trough
will shape the weather for the upcoming week.
For Sunday and Monday, dry weather temporarily returns to the
region as areas south of the North Platte River Valley could see
temperatures warm up into the mid-50s by Monday afternoon. A cold
front will push through during the day Monday resulting in areas
to the north remaining colder in the low-40s and upper 30s. This
front may trigger a few snow showers early Tuesday morning along
the Cheyenne Ridge, however these should remain light. A weak
shortwave looks to eject out from the Pacific low Tuesday which
could bring another chance for light precipitation Tuesday
evening across the southern NE Panhandle and farther east into
central Nebraska. Looking ahead, the Pacific low will begin to
propagate eastward resulting in a active weather pattern mid- to
late-week.
Currently, both the GFS and Euro slowly propagate the closed low
down the Pacific Coast before interacting with the sub-tropical jet.
As the upper low moves inland, models begin to depict strong lee
cyclogenesis over eastern Colorado starting Thursday morning. The
GFS deepens the sfc low to 994 mb while the Euro is slower and
stronger with a 990 mb sfc low slightly farther north. Both
solutions have a rather large precipitation field on the NW side
of the sfc low over much of eastern Wyoming and Nebraska and
strong northerly sfc winds in a rather tight pressure gradient
near the NE/CO border. With differences in positioning and timing
of the 500 mb low, upcoming shifts will need to keep a close eye
in the coming days.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 529 PM MDT Fri Mar 13 2020
Snow showers should become more scattered Rawlins east to Sidney
through the evening hours, even though periods of low ceilings and
freezing fog could be an issue for those areas, especially 02z-06z
before the winds become more southwesterly and downslope. Farther
east, periods of snow with visibilities and ceilings down to
IFR/LIFR through late evening before starting to taper off toward
morning. Low ceilings will likely hold across most western
Nebraska Panhandle sites tonight given favorable low level winds,
with the exception of Chadron which could see a downslope
component late tonight.
&&
.FIRE WEATHER...
Issued at 300 PM MDT Fri Mar 13 2020
Minimal fire weather concerns over the next several days. Areas of
southeast Wyoming likely to see accumulating snow...especially for
the mountains and areas east of the Laramie Range into the
Nebraska Panhandle. A low pressure system near the Four Corners
area this afternoon will continue to track towards the northeast
bringing this widespread snow. Snow ends Saturday morning...but
new snowpack will be in place to keep fuels wet. Dry Sunday and
Monday as high pressure moves over the area. Next chance for snow
looks to be Thursday into Friday next week as a strong low
pressure system tracks across northeast Colorado.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Weather Advisory until noon MDT Saturday for WYZ102-108-
112.
Freezing Fog Advisory until 6 AM MDT Saturday for WYZ116>118.
NE...Winter Storm Warning until noon MDT Saturday for NEZ002-003-021-
095-096.
Winter Weather Advisory until noon MDT Saturday for NEZ019-020-
054-055.
&&
$$
UPDATE...REC
SHORT TERM...GCC
LONG TERM...MB
AVIATION...JG
FIRE WEATHER...GCC
Area Forecast Discussion
National Weather Service Des Moines IA
632 PM CDT Fri Mar 13 2020
...Updated for 00z Aviation...
.DISCUSSION.../Tonight through Friday/
Issued at 312 PM CDT Fri Mar 13 2020
Tonight into Saturday...main forecast concern was focused on the
light snow potential across the central and southern sections of
the forecast area. The latest HRRR/RAP/NAM in decent agreement
with timing of the snow starting and location of the high amounts.
A slight change to the western portions of the forecast area with
higher QPF and thus higher snow amounts. Confident the precip type
will be either rain/snow with complete saturation in the
dendritic layer. Decent frontogenetical band of forcing sets up
from around Denison south-southeast through Des Moines down to
Lamoni and this area has a better chance to see the 2-3 inches
(isolated 4") of snow by late Saturday morning. This
frontogenetical band should be strong enough to overcome the deep
dry layer near the surface, but lower confidence with any snow
amounts further north, especially northward toward Highway 20 as
the forcing remains weak that far north and shouldn`t be enough to
overcome the surface dry layer. There looks to be a sharp
gradient of snow amounts and generally along and south of
Interstate 80. The latest RAP and GFS via Bufkit soundings are a
bit concerning with the slightly higher snow amounts in the Des
Moines area but did trend up the totals. However, roads
temperatures this afternoon range from 60-70F over central to
southern Iowa, so there will be plenty of melting before the snow
begins to accumulated. Obviously higher totals are likely on
grassy and elevated surfaces. The other caveat are the winds as
they will increase out of the east Saturday morning and look to be
enough to cause some visibility concerns, especially in the
aforementioned frontogenetical heavier band. The forcing and
moisture quickly move east of the forecast area past 18z Saturday
and thus pops rapidly drop off. Enough snow and wind to hoist a
wintery weather advisory over the west and south and there is the
potential it may need to be extended further northeast to include
the Des Moines metro if the snow amounts come in a bit higher.
Sunday into Wednesday...large surface high pressure dominates the
weather pattern providing a cool and dry period for much of the
state. Still looking at a cold front through Monday night, but the
bulk of the moisture remains north and kept the forecast dry for
now.
Thursday and Friday...ECMWF and GFS have come into decent agreement
with the timing and location of a fairly strong surface low to
eject out of the OK/TX Panhandles. The ECMWF is a bit slower and
a shade further south, but overall for 156-180 hour forecast,
surprisingly in good agreement. The majority of the forecast are
remains the warm sector and provides thunderstorm chances, but
there looks be a snow band to set up across the north to northwest
portions of Iowa Thursday night into Friday.
&&
.AVIATION.../For the 00Z TAFS through 00Z Saturday evening/
Issued at 632 PM CDT Fri Mar 13 2020
VFR conditions this evening will give way to deteriorating
conditions overnight through the day Saturday, primarily at
southern sites as snow moves across the state. KOTM/KDSM will see
IFR visibility towards sunrise as the heaviest snow arrives, with
MVFR cigs. Included a -SN mention at KFOD, however for now have
kept at VFR conditions as this will be the far northern extent of
the precip.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 1 AM to 3 PM CDT Saturday for
IAZ044-045-057-058-070>072-081>084-092>097.
&&
$$
DISCUSSION...Podrazik
AVIATION...Hagenhoff
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
1055 PM CDT Fri Mar 13 2020
.UPDATE...
Issued at 1050 PM CDT Fri Mar 13 2020
Have made some minor adjustments to POP and WX grids based on
radar, satellite and model trends. Thoughts below:
1) Have added some drzl/frz drzl. Areas without significant radar
returns are probably seeing this due to lack of saturation in DGZ.
These areas are transient and given marginal sfc temps near
freezing, doubt there will be much impacts. Perhaps some lt glaze
on elevated surfaces.
2) We`ve been in a lull late this eve, but models show uptick in
QPF in the 06Z- 12Z time frame. Thus, have not made any
significant changes to snow amounts. There`s still factors of
warm ground and wet snow/low ratios fighting against higher
amounts. Still think most areas in advisory will see 3-5", with
some isolated areas near 6" still possible. However, so far,
impacts to roads has been fairly minimal.
3) Didn`t make any headline changes on this shift, but may very
well need to move up the end time as most, if not all, appreciable
QPF should be done by ~15Z. Caveat to this could be lingering
potential for fzdz. However, even by 18Z will likely see temps
rise 1-2 deg, which combined with March sun angle, would be
enough to eliminate icing threat. Will let midshift coordinate
with neighbors on this potential update.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 342 PM CDT Fri Mar 13 2020
Aloft: As has been the case since mid-Nov...mainly zonal flow
remains over the CONUS. Aircraft wind obs and RAP dynamic
tropopause analyses indicated anticyclonic WSW flow over NEB/KS. A
shrtwv trof extended from the UT-CO border down into AZ. This
trof will lift NE and cross the CWA late tonight into tomorrow AM.
Heights will rapidly rise in its wake...with a broad ridge
forming over the Plns in response to the next low diving S along
the W coast.
Surface: 1050 mb high pres over Wrn Canada extended SE into the
Cntrl USA. The cool front that moved thru here Thu AM was over
Cntrl TX and the Gulf Coast states. Weak low pres will form along
that front tonight into tomorrow...while high pres conts to
dominate acrs Srn Canada. That will keep E winds over the CWA thru
tomorrow.
Rest of this afternoon: Radar mosaic shows predominantly -SN
overtaking the CWA. The leading edge is not reaching the ground
due to low-lvl dry air. Where temps have climbed into the low
40s...the leading edge of pcpn reaching the ground was falling as
-RA. Expect RA/SN to cont advancing NE.
NDOT traffic cams indicated snow accumulating on grassy areas
along Hwy 136 W of Riverton. Snow is probably accumulating over
Gosper/Phelps counties as well. With temps above frzg and
concrete/pavement still absorbing insolation...the snow was
melting on contact. So roads were just wet attm.
Tonight: Snow will overtake the entire CWA. Once the sun goes
down and roads and temps cool...snow will begin accumulating on
roads. Temps will fall to near 32F and hold steady. The latest
blend of mdl QPFs came in a touch higher than prvs fcsts. Snow
ratios were capped at 10:1 given near-frzg temp profile. That
still resulted in some 6" amts over parts of
Dawson/Gosper/Phelps/Furnas counties.
Winter Wx Advy conts as posted at 4 AM...but the possibility of 6"
amts necessitated upgrading Dawson/Gosper/Phelps/Furnas to a
wrng.
Given that this is a weak system...and no strengthening
expected...and initial melting and compaction due to warm
ground...most locations should remain at or below 5". Expect a
gradient of 1-5" from SE-NW acrs the CWA with isolated 6" psbl in
the warning area.
Sat: Snow will taper off and end during the morning from SW-NE.
There`s a chance a little snow could linger into early afternoon N
and E of I-80...but the accumulating snow will be over. Highs in
the 30s.
Wind will not be a big issue with this system as there is no sfc
low anywhere nearby. E 10-20 mph with some gusts around 25 mph at
times.
The wet character of the snow will minimize blowing and drifting.
After the snow ends...remaining cldy. There is a chance that some
patchy drzl could occur.
.LONG TERM...(Saturday night through Friday)
Issued at 342 PM CDT Fri Mar 13 2020
Aloft: Low-amplitude anticyclonic W-WSW flow will cont over
NEB/KS thru Tue...as a strong low sinks down the W coast...a low
remains over Hudson Bay...and a subtropical high remains parked
over the Caribbean. The W coast low is fcst to creep slowly inland
Wed and this will back winds to SW over the CWA. Some
acceleration is psbl Thu as another low dives into the backside of
the longwave trof. The last 2-3 runs of the EC/GFS-FV3/CMC are
now consistent on lee cyclogenesis Thu night with a new low
forming and briefly intensifying over NEB. It is then fcst to
weaken on its way into the upr Midwest Fri.
Surface: The strong high over Srn Canada will head E Sun. A very
wk cool front will form over the Nrn Plns Sun night and it will
cross the CWA Mon eve. Behind this front...another big Canadian
high will gradually slide ESE into New Eng by Wed. In the
meantime...the cool front will become stationary over the Srn
Plns. Lee cyclogenesis will begin over CO Wed. This will force the
front to lift back N as a warm front. The CO low will intensify
Thu. This is still a week out...so there are timing/location diffs
between the mdls...but that low is fcst to eject out acrs NEB/KS
Thu night into Fri. The warm front will probably lift as far N as
the state line. Meanwhile...a Canadian cold front will drop S Thu
night and merge with this system...increasing the temp grad.
Temps will average at or below normal thru next Fri. The
chilliest day will be Sun. Don`t expect much increase in temps
before Thu as this entire fcst is looking very cldy. We could see
a temporary pop in temps Thu as the warm front gets close...but
the cool front will quickly follow Fri.
Precip: As with yesterday...NBM has a lot of pops/precip chances
that I really don`t think are warranted for large portions of time
between Sat night thru Mon night. Am not saying it will be
completely dry...but whatever falls will be very light and minor.
Changed the character of the precip to drzl as clds will be very
shallow and all liquid/no ice. The next legit rain chances will
arrive Tue night into Wed and then Thu-Fri. Rumbles of thunder
still possible...espcly Thu night. This Thu-Fri system could be a
soaker for S-cntrl NEB...espcly W and N of the Tri-Cities. Hvy wet
snow will be psbl NW fringe of the CWA.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday)
Issued at 653 PM CDT Fri Mar 13 2020
Significant wx: Prolonged period of IFR conditions.
Tonight: High confidence for IFR CIGs and VSBYs. Minimum CIGs and
VSBYs could drop to LIFR at times during heaviest bands. E winds
will gradually incr this eve, with gusts 20-25kt overnight. Expect
2-5 inches of snow accumulations during this time.
Saturday: High confidence IFR CIGs through much, if not all of
daytime hrs Sat. IFR VSBYs will most likely be ongoing at start
of the period in continued -SN. Additional inch or so of
accumulation expected 12-18Z. Eventually, expect VSBYs to improve
to MVFR levels by mid to late morning as snow decr, but lingering
boundary layer moisture and upslope component to winds may allow
light fog to continue thru daytime. Expect continued IFR CIGs and
return to IFR VSBYs Sat night.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory until 4 PM CDT Saturday for NEZ039>041-
046>049-061>064-074>077-083>086.
Winter Storm Warning until 4 PM CDT Saturday for NEZ060-072-073-
082.
KS...Winter Weather Advisory until 4 PM CDT Saturday for KSZ005-006.
&&
$$
UPDATE...Thies
SHORT TERM...Kelley
LONG TERM...Kelley
AVIATION...Thies
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
948 PM CDT Fri Mar 13 2020
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
Only a few light showers over the far north indicated on radar,
but not going to rule out a few more overnight overtop the stalled
boundary over south MS. Of greater concern will be the fog
potential over the southeast after midnight. HRRR has been
persistent with areas of dense fog moving into these areas, but at
present, closest fog showing up in buoy data well offshore./GG/
Prior discussion below:
Tonight and Tomorrow:
The front is now lingering along the I-20 corridor this afternoon
with all of the precip developing to the north of the boundary.
Precip continues to be light and showery throughout those areas. To
the south of the boundary, clouds are breaking up and temperatures
have risen nicely into the upper 70s and lower 80s. Going into
tonight, the showers are expected to diminish as the limited
instability decreases even more. Patchy fog will develop along the
Gulf Coast overnight and spread northward into our Pine Belt region.
The boundary will begin a shift northward early Saturday morning and
winds will shift out of the south again. As for Saturday, with the
warm front lifting ever farther north into eastern OK to the Mid-
Mississippi Valley, only limited rain chances are expected within
our CWA. The counties/parishes in our northwest CWA and closest to
the boundary may see some showery activity in the morning. With warm
air advection picking back up throughout the area, temperatures
areawide will warm into the upper 70s to lower 80s. /10/
Saturday night through next week...
Chances for showers and isolated thunderstorms remain in the
forecast through most of the period. With ridging over the
region, the best chances for this activity will remain across the
northern part of the forecast area. Ridging will dampen some
Saturday night into Sunday as another front drops into the region.
This will allow for quasi-zonal flow to be in place, with
disturbances passing through every day or couple of days. Again,
the best chances for rain will be in the north. During this
period, temperatures will be very springlike, especially across
the southern sections of the ArkLaMiss, which may not see as much
rain. Across northern parts, thanks to clouds and rain, highs will
be in the 60s and may reach 70. However, highs will easily reach
the 70s and even some lower 80s in the south through the week.
Overall, it looks to be a rather wet period through much of the
week with multiple disturbances moving through. /28/
&&
.AVIATION...
00Z TAF discussion: A cold front, south of a TVR-JAN-MEI line,
will become stationary this evening and begin moving back to the
north Saturday morning. To the north of the front, MVFR ceilings
and isolated showers will continue through much of the period as
winds stay from the northeast at around 10 knots. To the south of
the front, southerly winds around 5 knots early will diminish by
mid evening. Thereafter, IFR and LIFR conditions will develop from
the south as areas of fog move inland from the Gulf of Mexico.
These conditions will continue until mid morning then slowly
improve through the afternoon./GG/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 63 80 61 74 / 15 13 24 21
Meridian 61 81 61 77 / 17 7 17 24
Vicksburg 64 80 61 70 / 18 20 27 25
Hattiesburg 61 82 59 83 / 10 5 3 7
Natchez 64 80 62 76 / 10 12 13 17
Greenville 53 75 53 58 / 23 32 79 44
Greenwood 57 77 56 62 / 23 27 73 46
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
Area Forecast Discussion
National Weather Service Midland/Odessa TX
649 PM CDT Fri Mar 13 2020
.DISCUSSION...
Please see 00Z aviation discussion below.
&&
.AVIATION...
Sfc winds have increased around 12-15 kts this evening out of the
ESE ahead of a strong upper-level system. Isold -TSRA have
developed INVOF CNM and PEQ and will continue to migrate ENE
through tonight affecting all terminals through 06Z. Currently
IFR VIS w/FG has set in behind a cold front at MAF and HOB and
gradually improvent is likely tonight as -TSRA move through
remaining TAF sites. Some storms could produce hail and gusty
erratic winds. CIGS/VSBY should improve to VFR at most terminals
between 04-06Z.
&&
.PREV DISCUSSION... /issued 126 PM CDT Fri Mar 13 2020/
DISCUSSION...
Kinematic and thermodynamic parameters are setting up for a round
severe wx starting late this afternoon as a 130kt 3h jet moves
across the area into the overnight. Deep convective initiation will
likely be delayed due to limited insolation and thus importance of
jet. Initiation on high resolution models is probably a few hrs
early, but is expected to occur in the far wrn CWFA. Storms and
attendant threats will largely be determined by a cold front that
will be located INVOF Pecos River and its potential to move n as a
warm front into the overnight. Of course there is some uncertainty
WRT the frontal position and therefore temps and CAPES this PM.
For now we are most concerned about the discrete supercells in and
around Reeves, Winkler, Ward, Pecos, Crane, Midland, Ector, Upton,
Reagan, and srn Lea Counties. Concerns could be farther s and w
depending on the front and when it starts to move back to the n.
Derived severe wx indices/parameters and soundings are indicative
of tornadic potential and splitting supercells. 12Z-15Z HRRR
simulated radar suggestive of multiple discrete cells with long-
lived strong updraft helicity tracks across wrn/srn PB and Pecos
County. We have collaborated with SPC/SJT and risk has been
increased to enhanced earlier today. Tornadoes are possible today
(see SPC TOR probabilities), even a strong tornado cannot be
ruled out and the most favored area for a tornado will generally
be bound between I-20 and I-10. Storms that move farther n in wake
of the front will be elevated, but nonetheless still maintain
severe potential, parcels lifted from 85h still result in CAPES
around 1000 J/KG. We are also concerned that instability could be
maximized in the Lower Trans Pecos and the Big Bend area, there
are lots of vacationers down at BBNP and we have increased PoPs
there. Sat temps will increase and conditions will dry in wake of
the exiting system. The cold front will surge back s late Sat
night-Sun AM setting up SUN PM to possibly be much cooler (NAM12
has highs in the 40s for much of the PB!). Another mid-level speed
max in the sw flow aloft will attempt to generate some light
precip in combo with low-level waa aloft the front. A mid-level
speed max will come out of MX Sun night with a cluster of storms
moving across Trans Pecos, somewhere from the Davis Mtns-Terrell
Co. Cold air may be slow to erode out the PB Mon? Active and
probably wet sw flow still advertised Tue-Thur.
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 53 74 50 60 / 80 0 20 80
Carlsbad 47 74 48 67 / 10 0 10 50
Dryden 62 82 61 77 / 30 0 10 40
Fort Stockton 54 77 58 74 / 30 0 20 60
Guadalupe Pass 43 63 47 64 / 10 0 0 30
Hobbs 46 72 47 60 / 50 0 10 70
Marfa 46 76 48 77 / 10 0 0 20
Midland Intl Airport 53 76 53 63 / 70 0 20 80
Odessa 53 76 53 64 / 70 0 20 80
Wink 51 77 53 68 / 40 0 10 70
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&
$$
24
Area Forecast Discussion
National Weather Service Pueblo CO
542 PM MDT Fri Mar 13 2020
.UPDATE...
Issued at 539 PM MDT Fri Mar 13 2020
Based on current observations (CDOT Cams) and a variety of
guidance, have issued a dense fog advisory for El Paso County into
tomorrow morning. Conceptually, with upslope flow continuing
through tonight, moist airmass already in place and trough still
to our west, dense fog will be possible and it will likely be
widespread. We may also need a dense fog advisory for the far
eastern plains later this evening.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 333 PM MDT Fri Mar 13 2020
Upper low shearing eastward and weakening across Colorado this
afternoon, with main warm advection band and associated precip
shifting eastward into KS. Still a good deal of instability driven
convection across the area, and even a couple lightning strikes
noted along the crest of the nrn Sangres as of 21z. For this
evening and overnight, HRRR suggests one last band of heavier
precip developing over Fremont/El Paso/Pueblo counties toward 00z,
which seems plausible given increasing convection over the
Sangres/Wets late this afternoon. Will keep relatively high pops
in place over/downstream of the eastern mountains to account for
this, then precip fairly quickly fades away after sunset. Not
expecting big snow accums, but a few spots along/west of I-25
could get a quick inch or two. Elsewhere, still a few more hours
to go of scattered to numerous snow showers, and will hold on to
current set of highlights into the evening. Latest look at mid
level temps suggests column should stay cold enough for mainly
snow this evening, with perhaps a rain/snow mix in areas south of
the Arkansas River where surface temps are well above freezing.
Some patchy fog likely over nrn El Paso county given continued
sely upslope, though soundings and most numerical guidance begin
to improve visibility after midnight as flow weakens and some
slightly drier air begins to mix in. Expect bulk of any precip to
be done by midnight, with just some lingering light snow through
the night along the Continental Divide. Clouds may be slower to
clear, especially over the plains where ely component to the
surface flow persists.
On Saturday, mainly dry across the area in the wake of departing
trough, with only a few -shsn along the Continental Divide in the
afternoon. Max temps will be warmer over the mountains and
interior valleys, while temp forecast on the plains is rather
problematic with easterly surface flow persisting for much of the
day. Still expect I-25 corridor to warm with more sun, while areas
close to the KS border where stratus may linger will stay mainly
in the 40s.
.LONG TERM...(Saturday night through Friday)
Issued at 333 PM MDT Fri Mar 13 2020
Much of the extended period appearing to remain active, beginning
Saturday night into Sunday morning and again possibly Sunday
night into Monday morning. Southwesterly flow expected to remain
in place for much of the weekend into early next week. In this
pattern, a period of WAA appearing likely across much of the
region, especially along the eastern plains. As conditions moisten
or remain relatively moist, could first see light precip
development Saturday night over parts of the lower elevations and
plains especially with low level upslope flow in place. With
forecast soundings showing this low level moisture along with some
weak ascent, could see some light precip development. Most
guidance is indicating this possibility, with developing some
light qpf. With some increased confidence for this potential, did
add pops to the forecast late Saturday night. At this point, any
development is appearing to remain light and did add drizzle
wording. With the potential for temps to be around freezing, did
also include some freezing drizzle wording. Highest confidence for
this potential is over the plains closer to the Kansas border,
however, it is possible for this development to reach parts of the
I- 25 corridor. Similar setup appearing possible again Sunday
night, though upslope flow not expected at this time.
Quiet and warm conditions expected on Monday for much of the
area, with highs expected to rise into the 60s and 70s. This
warmth looking to be brief, as a front expected to drop south
across the region late Monday into Tuesday. In it`s wake, guidance
showing easterly upslope flow to support our next chances of
precip during this time frame, and possibly lingering into early
Wednesday. Not as much cold air with this front, so precip should
stay mainly rain but can`t rule out a rain snow mix. By the middle
of next week, will begin to focus on a potential larger system to
move across the western CONUS and towards the region. Definitely
some big difference among guidance on overall evolution and timing
of this system. However, more widespread precip chances are
appearing more probable by middle/late of next week. Not only is
wintry precip expected, but potential increases in moisture and
instability could support thunder across parts of the area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 333 PM MDT Fri Mar 13 2020
At KCOS, still some fog and flurries at the terminal late this
afternoon, with IFR/LIFR conditions persisting. Still one more
period of heavier snow 23z-02z before precip ends later tonight.
While model guidance suggest cigs/vis improving to MVFR late this
evening, suspect clearing/improvement will be much slower given
southeast surface winds, and will hold on to lower clouds until
winds weaken toward 12z Sat. VFR then expected Sat.
At KPUB, MVFR cigs will persist, with a brief period of IFR cigs/vis
due to snow showers possible 23z-02z. Slowly improving cigs then
expected late tonight, with VFR conditions on Sat.
At KALS, still a risk of a brief shower with MVFR cigs/vis into the
evening, before precip ends 03z-06z. VFR conditions then expected
overnight into Saturday.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until midnight MDT tonight for COZ068.
Dense Fog Advisory until 9 AM MDT Saturday for COZ084-085.
Winter Weather Advisory until midnight MDT tonight for COZ073-
075.
&&
$$
UPDATE...HODANISH
SHORT TERM...PETERSEN
LONG TERM...RODRIGUEZ
AVIATION...PETERSEN