Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/14/21
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
553 PM MST Sat Mar 13 2021
.UPDATE...
Updated the Winter Weather Advisory to remove the western zones given
current web cams showing little to no impact to roads, latest HRRR
and HREF showing very little additional accumulation and our forecast
of fairly low PoPs overnight. A couple northwest zones may need
fresh advisories for Sunday morning given an 2nd round of snow
developing on the backside of the then departing upper low. The
northern mountains still look to benefit from this event, which will
continue through Sunday, with over one foot possible on the peaks
and higher west-facing slopes.
11
&&
.PREV DISCUSSION...436 PM MST Sat Mar 13 2021...
.AVIATION...
00Z TAF CYCLE
A mixed-bag of strong winds, dust and snow across our area this
evening, with VFR to LIFR conditions and areas of mountain
obscurations. IFR conditions at KROW in blowing dust are forecast to
improve to VFR later this evening. LIFR conditions in snow at KFMN
forecast to improve to MVFR early evening, but may dip back down to
IFR Sunday morning with another round of snow forecast to move
southeast around the backside of the slowly departing upper low. This
second round of snow is forecast to impact KGUP Sunday morning as
well, but with MVFR conditions. Otherwise, the big story is the
strong winds that will continue overnight and through Sunday. Strong
westerly winds may bring the redevelopment of blowing dust at KROW
Sunday afternoon, but kept VFR for now. The northern mountains and
portions of the western mountains will be obscured all day Sunday.
11
&&
.PREV DISCUSSION...325 PM MST Sat Mar 13 2021...
.UPDATE...
Update was made to add the Sandia/Manzano mountains zone as Wind
Advisory for the overnight hours.
31
&&
.PREV DISCUSSION...313 PM MST Sat Mar 13 2021...
.SYNOPSIS...
As severe thunderstorms continue to shift east of the New
Mexico/Texas border, the focus turns to the low pressure moving over
the Four Corners Region. This winter storm will bring accumulating
snow to the northern and western portions of the state, with a few
inches expected across the lower elevations west of the Continental
Divide and up to a foot or more total across the highest peaks.
Stronger to potentially damaging winds are expected on Sunday with
gusts of 60-65 mph possible, and rain and snow showers continuing
through Sunday night. A brief break on Monday occurs, before another
storm system brings windy conditions, cooler temperatures, and
another round of snow for the northern mountains. Quieter weather is
forecast for the remainder of the week.
&&
.DISCUSSION...
SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)...
A broad and strong upper level low pressure system will continue to
produce accumulating snow mainly over western and northern areas as
it passes eastward along the CO/NM border tonight through Sunday.
Wrap around moisture will cause showers to linger over the northern
mountains into Sunday night as the system exits to the northeast. A
few to several inches of additional snow accumulation are expected
in the northern and western mountains, with the heaviest amounts of
over 6 inches above 8500 feet in the northern mountains. Lower
elevations of the north and west should also accumulate an inch or
so of additional snow, except for up to 3 inches around Zuni and
Fence Lake, as well as from Cuba to Dulce.
The storm is also steering a strong speed maximum in the polar jet
stream over the state with 700 mb winds expected to peak from 40 to
65 kt across western and central parts of the forecast area on
Sunday. The flow will begin to strengthen over higher elevations
tonight, so we will keep a Wind Advisory going through tonight over
the central and south central mountains including Clines Corners.
With the storm system passing eastward along NM`s northern border, a
fair amount of cloud cover is expected on Sunday, which is known to
inhibit atmospheric mixing and result in weaker winds, so we opted
not to upgrade the High Wind Warning yet. Will let the nigh shift
factor in the latest model data and sky cover forecast in the
warning decision. At this time it does look like higher peaks and
Clines Corners have the best chance of 60 mph gusts on Sunday.
Initially these winds will blow out of the west, but they will shift
out of the northwest as the day progresses. Winds will weaken as the
jet migrates east of NM Sunday evening.
LONG TERM...(MONDAY THROUGH SATURDAY)...
As a shortwave ridge passes overhead on Monday, temperatures warm
5-10 degrees compared to Sunday`s highs. Breezy to locally windy
conditions will continue, mainly east of the central mountain chain,
as a leeside low develops over NE NM/SE CO.
Another upper level low treks south and east from northern CA into
the Four Corners region by Tuesday. While 12z models differ on the
exact placement and timing of this system, this quick-hitter will
bring light snow accumulations to the northern mountains, with a
couple inches possible. In addition, soundings indicate strong
mixing up to 500-600 mb and a 100+ kt 300 mb jet, so another round of
strong westerly winds is possible Tuesday afternoon. 700 mb winds are
highest over the Sierra Blanca Mountain Range, indicating speeds of
50-60 kts. The ECMWF keeps wrap around precipitation lingering across
the northeast corner of the state through Wednesday morning and with
higher QPF, while the GFS is quicker to exit eastward. Didn`t stray
much from NBM POPs, keeping slight chance and chance for rain and
snow showers Wednesday morning.
A weak ridge begins to build to the west late Wednesday and shift
over the state by Thursday, but temperatures aren`t forecast to warm
to above normal across a majority of the state until Friday and
Saturday. While wind speeds will be generally lighter than earlier in
the week, breezy to locally windy conditions are forecast by
Saturday afternoon, as southwesterlies strengthen aloft. There is the
potential for another system to arrive late next weekend. Stay
tuned.
44/31
&&
.FIRE WEATHER...
A storm system will continue to bring accumulating snow to northern
and western areas tonight through Sunday, as well as strong west and
northwest winds to the entire forecast area on Sunday. Breezy
southwest winds will return in the wake of the exiting system on
Monday. Another storm system will move in from the west on Tuesday
with more strong winds over a broad area. Temperatures will cool
below normal Tuesday, except across the east where humidities will
be low enough for fire weather concerns. The Tuesday system will
probably bring more snow accumulation to the northern and western
mountains. A ridge of high pressure will then cross from the west
during the latter half of the week with warming temperatures,
relatively light winds and dry weather.
44
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
High Wind Watch from 6 AM MDT Sunday through Sunday evening for the
following zones... NMZ206>208-219>224-226-233-239>241.
Wind Advisory until 6 AM MDT Sunday for the following zones...
NMZ223-226.
Wind Advisory until 6 AM MDT Sunday for the following zones...
NMZ221.
Winter Weather Advisory until midnight MDT Sunday night for the
following zones... NMZ210-211-213-214-227.
Wind Advisory until 7 PM MST this evening for the following zones...
NMZ233>240.
&&
$$
as of this forecast discussion and it looks like how the system
is evolving we will probably see areas roughly from Liberal to
Pratt getting in on the slightly milder air this evening. Overall
the heavy rain event with totals from 1 to 3 inches this evening
and Sunday morning still looks to be a good bet for much of
southwest Kansas.
Detailing the severe weather threat this evening many of the CAM
models are suggesting a fast growing upscale bow echo from around
Lubbock, TX to Syracuse late this afternoon and racing eastward
through this evening. 0-6 km bulk shear values from SPC
mesoanalysis are high already (70-80 kts out of the southwest) and
will continue to stay that way as this large dynamic system moves
closer to the plains. From looking at forecast skew-t models the
convection will have mainly elevated CAPE and the threat will be
mainly strong winds and large hail. Tornado threat isn`t looking
all that great outside of perhaps a brief QLCS tornado spin
up...but even this threat remains low at this point as the
forecast bow echo would be running pretty much parallel to the 0-3
km bulk shear direction. Storm motion will also be fast this
evening going at about a 40 kt clip as it moves through southwest
Kansas. The main upper low looks to move into southeast Colorado
by Sunday morning and we should see a gradual ending to the rain
from west to east after midnight tonight. With the large amount of
rain and inversion with light winds I also included fog potential
again for areas west of Dodge City which may need expansion
depending on when the rain ends in our eastern zones.
For Sunday it looks like a large dry slot on the southwest side of
the low will move across southwest Kansas during the day clearing
out most of the rain before noon and we could also see some
sunshine breaking through. By the afternoon we could see some
showers and thunderstorms develop with the lifting in the vicinity
of the upper low in northwest Kansas. Overall should be a day
where most of us will dry out and highs should reach into the 50s
and 60s.
.LONG TERM...(Sunday night through Saturday)
Issued at 102 PM CST Sat Mar 13 2021
The storm system from the short term will slowly start to move
northeastward on Monday and we could see some wrap around
precipitation mainly for areas near I-70 Monday morning and by the
afternoon the precipitation chances should exit the region. The
upper level winds turn southwest for Tuesday ahead of the next
upper level storm system which will be located near the four
corners region.
Next chance of rain will be with a closed low that moves from the
four corners region into the Texas panhandle Tuesday night into
Wednesday. Rain will overspread much of southwest Kansas Wednesday
morning and we could see QPF values in the 0.50 inch or more range
again with this mid week system. Colder air looks to wrap into the
system Wednesday evening so the potential for snow will need to be
monitored but at this point it looks like we should stay above
freezing for the event. Once the storm system exits the region we
should stay in a regime of colder air through the end of the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 503 PM CST Sat Mar 13 2021
Expect very poor aviation conditions to continue through 12z Sun.
Widespread IFR/LIFR cigs and/or visibility will continue with
stratus, areas of fog, and mist. Additionally, numerous showers
and thunderstorms will impact all airports and all of SW KS
through tonight. Rain will be very heavy at times. Following the
HRRR on timing, the back edge of the rain/thunderstorm shield
should reach GCK/LBL/DDC around 10z Sun, and HYS by 12z Sun.
Expect VFR to quickly return after 12z Sun, continuing daylight
Sunday. After 15z Sun, strong S/SE winds are expected at all
airports, gusting 30-35 kts.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 39 59 35 54 / 100 10 10 10
GCK 36 56 33 52 / 100 30 10 10
EHA 31 56 32 57 / 50 10 10 0
LBL 31 58 33 56 / 80 10 10 0
HYS 44 61 36 52 / 100 60 20 40
P28 48 65 39 59 / 100 30 10 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Sunday afternoon for KSZ030-031-045-046-
064>066-078>081-088>090.
&&
$$
UPDATE...Turner
SHORT TERM...Tatro
LONG TERM...Tatro
AVIATION...Turner
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
608 PM CST Sat Mar 13 2021
.DISCUSSION...(This evening through Saturday)
Issued at 415 PM CST Sat Mar 13 2021
Main concerns are rain amounts and strong winds over next 24-36
hours, then the potential for another storm system middle of next
week.
Rain has been on the incr during the day today, and even seeing
some weak convection and lgtn per latest ENTLN plots. Can`t
completely rule out an isolated strong storm with mainly a
marginal hail threat given steep lapse rates/cool mid level temps
and strong shear. SPC has southern areas clipped by Marginal risk.
Short term hi-res guidance and 12Z HREF are in good agreement in
bringing nearly continuous waves of shwrs/weak convection thru the
area tonight and into Sun AM. Other than the small hail potential,
main concern will be potential for areas of moderate or locally
heavy rain given well advertised abundant deep layer moisture and
persistence of rain. Latest NAEFS output places PWs near
climatological max (above 99th percentile) and latest ECMWF EFI is
nearly maxed out. Luckily MUCAPE values remain weak, which should
help keep rates in check and allow dry soils to absorb much of the
pcpn tonight. Winds will be on the incr as sfc low deepens over
the High Plains, with gusts of 40-45mph possible overnight.
The primary upper low will cross the Rockies onto the High Plains
Sun AM, become vertically stacked, and move very little Sun thru Sun
night. As the upper low occludes, expect the arc of moderate to
locally heavy rn to gradually lift N/NE thru the day as dry air is
wrapped in from the SW. Some guidance continues to indicate
potential for some wet snow to mix in over the far N as early as
Sun aftn. This seems a bit bullish, and even if this happened, wet
sfc conditions and temps in mid to upper 30s would likely negate
the potential for any snw accums. Further S, it`ll be interesting
to see exactly where a potential clearing line and occluded bndry
set up as, in theory, this could be a focus for widely scat low
topped convection during the aftn. Latest HREF/SREF show the
potential for as much as 500-750 J/kg of SBCAPE over KS zones by
21Z, in the presence of 30-45kt deep layer shear. Hodographs in
this area are fairly straight or even a bit counter-clockwise in
the 1-3km layer and WBZ levels are quite low. This suggests
potential for small hail in the more sustained updrafts. Of
course, this is conditional upon tstm development at all. It`s
certainly a cold core system, so it just wouldn`t take much sfc
clearing/heating to take advantage of steep lapse rates. Something
to keep an eye on for tmrw aftn.
The other issue for Sun will be strong winds. Latest guidance
gives 25-30kt of sustained E-ENE sfc winds, with very strong
winds in excess of 60kt in a layer between 2000-5000ft AGL.
Obviously, mixing won`t be that deep given E component and thick
cld cover, but mixing to even 1000 ft could result in some
40-45mph gusts, perhaps as high as 50mph, mainly along and N of
I-80 during the daytime hrs. So certainly very RAW conditions
given continued rain and cool temps in the 40s. Areas further S
could rise into 50s to near 60F depending on aforementioned
clearing.
Pcpn rates will continue to decr Sun night as upper low fills and
dry air continues to wrap in. Nonetheless, rain/snow chcs continue
into Mon as core of upper low pivots NE right over the CWA. With
the cold mid level temps overhead will still have potential for
some wet snow mix in thru the AM for N/W portions of CWA, but
again, not expecting any accums/impacts. Winds will be lighter and
still be out of the E, so the upslope component and abundant low
level moisture could support some fog development Sun night into
Mon AM. Otherwise, below normal temps continue with highs in the
40s to near 50F.
Yet another upper level disturbance will swing thru the Central
Plains late Tue into Wed. This system has trended deeper and more
closed compared to a couple days ago. Both EC and GFS track the
upper low S of the area, from TX/OK Panhandles into the Ozarks,
with the GFS it`s usual fast bias relative to the EC. Given the
closed nature of the low, favor the slower EC. The current
forecast track would place the deformation band over roughly S/SE
half of CWA, and would typically expect this to be a band of
heavy/wet snow. However, latest operational models show a distinct
lack of negative H85 temp anomalies, suggesting little in the way
of Arctic air in place ahead of system to work with. Thus, the
system would need to create its own cold air to produce snow.
This remains possible, but not overly likely attm. So forecast
generally calls for cold rain or rain/snow mix.
Should finally see some warmer and drier conditions return towards
the end of next week into next weekend.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday)
Issued at 603 PM CST Sat Mar 13 2021
Widespread heavy rainfall is expected through early Sunday
afternoon. Even by later Sunday afternoon we could still be
getting some decent rain, but the heaviest will likely fall
between now and early Sunday afternoon. We are seeing some
lightning around the area and that will likely continue for at
least the next few hours with more isolated lightning as we get
later into tonight. The wind will be rather strong and gusty out
of the east especially Sunday morning with some gusts to around 45
mph. Strong low level wind shear is also possible at times Sunday
morning.
&&
.HYDROLOGY...
Issued at 415 PM CST Sat Mar 13 2021
As mentioned above, still think most areas will be fine in terms
of hydrological concerns given antecedent dry conditions and
limited rain rates. However, latest HREF 48hr PMM and QPF output
from longer runs of HRRR and RAP suggest localized areas could see
total rain amounts as high as 4-4.5", esp. for areas from near
GRI northeast towards OLU. There has also been a bit of an uptick
in latest SREF means. As a result, overall total QPF has trended
about 0.25-0.50" higher over past 12-24hrs. We have several river
forecast points that forecast to reach action stage, with a few
possibly rising into minor flood stage. This suggests to me that
some localized minor flooding could occur over next 48hrs, mainly
in known trouble spots for areas generally NE/E of the Tri Cities.
Not enough has changed to go with formal Flood Watch, but did
mention isolated minor flooding potential in latest HWO.
&&
.CLIMATE...
Issued at 435 AM CST Sat Mar 13 2021
How unusual is the March rainfall we have in the forecast over the
next 2 days? Looking back, the largest 2 day totals for rainfall
during the month of March are 3.12 inches in Hastings (1987) and
3.33 inches in Grand Island (1979). Given the current forecast,
both these precipitation totals could be challenged over the next
48 hours, so this is a pretty significant event which could have
very beneficial impacts on existing drought conditions. To put
things in perspective, during a "normal" March, about 1.8 inches
of precipitation is recorded in Grand Island.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
DISCUSSION...Thies
AVIATION...Wesely
HYDROLOGY...Thies
CLIMATE...Rossi
Area Forecast Discussion
National Weather Service Grand Junction CO
450 PM MST Sat Mar 13 2021
.SHORT TERM...(Tonight through Sunday night)
Issued at 251 PM MST Sat Mar 13 2021
As models had predicted, the mid-level low pressure system has
closed on the Four Corners region early this afternoon and RAP
analyses had the system`s center over Page, Arizona as of 20Z.
Upglide and broad mid-level upward forcing depicted in q fields
has resulted in snow and a rain/snow mix over southeast Utah with
snow across elevations above ~5500 feet. Snow cams at the
Telluride and Purgatory ski areas indicated light snow and 1
inch of new snow. The dry slot which was over the Rockies this
morning largely kept snow out of those areas, but snow has begun
to develop and will be increasing as the day progresses.
Later this afternoon and tonight the low tracks eastward along
the southeast Utah/southwest Colorado borders moving over the
southern San Luis Valley, then to the southeast Plains of
Colorado by morning. The moisture wrapped system will deepen
moisture depth across the area while broad mid-level upward
forcing persists. Consequently, precipitation will become
widespread with areas of rain or mixed precipitation in the lower
elevations largely changing over to snow. However, warm surface
temperatures will cause some melting, limiting accumulations.
Mountain snow, on the other hand, will begin to accumulate in
earnest.
The storm center moves little on Sunday so expect little change in
conditions across the area. Daytime warming, however, will cause
another shift in precipitation state for the lower elevations.
Finally, on Sunday night, the storm center is expected to kick
eastward over the central Plains which will result in a drying
trend from west to east during the night. Latest highlights
appeared to be on track, so will make no changes with this
forecast package.
Temperatures appeared too cold tonight and tomorrow night given
cloud cover in the absence of cold air advection so raised them
following MET/ECS guidance. Similar thinking and methodology
applied to Sunday`s temperatures which are expected to run close
to 10 degrees below normal.
.LONG TERM...(Monday through Friday)
Issued at 420 AM MST Sat Mar 13 2021
Lingering showers will taper off as the last of the current system
drags across the divide on Monday. A second low pressure system
will sit over northern California Monday morning and then slowly
move eastward toward the four corners region on Tuesday. While some
uncertainty remains as to the exact depth and timing of this system,
models seem to be in better agreement this cycle. The trough axis
then continues eastward...moving onto the plains by Wednesday. All
said and done, it appears that this second system will bring very
little QPF in the low valleys with around 3/10 inch to much of the
high country...which translates to around 3-6 inches of new
snowfall. With a large mid level low remaining in place off the
Pacific Northwest, a ridge then builds in over the Intermountain
West on Thursday and is expected to last through at least the first
half of the weekend.
Temperatures in the long term start out around 5 to 10 degrees below
normal in the midst of the mid levels lows. Conditions will slowly
warm moving toward the weekend as high pressure builds into the
region. Highs will sit 5 to 10 degrees above normals by Friday
(nearly 20 degrees warmer than today in many low / mid
elevations).
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 450 PM MST Sat Mar 13 2021
Expect numerous amendments this evening as main part of this storm
tracks across southwest Colorado into the northeast part of the
State. MVFR or lower flight criteria will become more widespread
as many snow form as moisture wraps around the system. MVFR or
worse conditions will continue well into Sunday as cold air and
light to moderate snowfall impacts flight conditions. Large spread
in guidance for cigs and vsby by 12Z in many places for very low
confidence forecast beyond 09Z.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory until 6 PM MDT Sunday for COZ003-017.
Winter Weather Advisory until 6 AM MDT Monday for COZ018-019.
Winter Storm Warning until 6 AM MDT Monday for COZ010-012.
Winter Weather Advisory until midnight MDT Sunday night for
COZ004-009-013.
Winter Weather Advisory until noon MDT Sunday for COZ001.
UT...Winter Weather Advisory until 6 PM MDT Sunday for UTZ025-028.
Winter Storm Warning until 6 PM MDT Sunday for UTZ023.
&&
$$
SHORT TERM...NL
LONG TERM...KJS
AVIATION...TGJT
Area Forecast Discussion
National Weather Service North Platte NE
539 PM CST Sat Mar 13 2021
.SHORT TERM...(This evening through Sunday night)
Issued at 257 PM CST Sat Mar 13 2021
NDOR cameras on I-80 and elsewhere indicate snow levels this
afternoon have dropped to 4000ft across the Panhandle and this
progression is occurring from south to north; associated with the
northward propagation of cold air aloft from the deep storm over
Colorado.
Excluding the warmer GFS model, time series plots of hourly
temperatures Sunday across the Sandhills strongly suggest slowly
falling temperatures throughout the day Sunday and on into the
evening and overnight hours. Cold air aloft will continue to
propagate north into Nebraska Sunday as an h700mb low across the
Rockies moves east into KS. This should support a changeover to snow
at elevations below 4000ft by morning and then down to 3000ft during
the day Sunday. Coordination with neighbor offices suggest snow
levels could drop a bit lower but remain mostly above 2500ft.
The latest snow forecast uses 35F as a threshold for all snow which
is probably correct for dynamic cooling events. This produced 3 to
around 14 inches of snow from about midnight tonight through 00z
Sunday evening. The models are in good agreement showing easterly
500m AGL winds around 25 to 35kt Sunday which supports sfc winds
around 25 to 35 mph. If not for the heavy wet nature of the snow and
temperatures near freezing, blizzard warnings would be obvious in
some areas. Blizzard warning is now in effect across Sheridan county
where temperatures will be below freezing Sunday morning. This
warning may need to be expanded east into western Cherry county
depending on the progress of the storm.
For this forecast, an upgrade to a Winter Storm Warning is in place
across Grant and Cherry counties and winter weather advisories are
in place across much of the Sandhills. The new winter storm warning
and weather advisories across the Sandhills are in place from 12z
Sunday to 12z Monday. The most widespread accumulating snow should
fall during the day Sunday but this weather system has been plagued
with timing problems- the models have been too fast. The makes
continuing the winter weather warnings and advisories until 12z wise.
The spectre of this storm affecting the remainder of ncntl Nebraska
Sunday night looms on the horizon as the GFS and ECM suggest the
potential for significant wet snow in that area Sunday evening.
Thus, depending on the progress of the storm winter, advisories may
need to be extended east with later forecasts.
The NAM and RAP model continue to show areas of a few hundred joules
of elevated CAPE tonight and early Sunday morning. Isolated
thunderstorms are in place across the southern Sandhills and
southwest Nebraska during this time.
.LONG TERM...(Monday through Saturday)
Issued at 257 PM CST Sat Mar 13 2021
The last vestiges of the weekend storm will depart Monday morning
with light snow ending across wrn and ncntl Nebraska.
A second storm will be crossing the srn Rockies Tuesday, taking aim
on the Central Plains Wednesday. The track of the storm for this
forecast appears to be across KS and the midsouth. Chance POPs are
in place across wrn and ncntl Nebraska Tuesday night through
Wednesday night. Temperatures are very marginal for snow. The
forecast is dry Thursday and beyond.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 539 PM CST Sat Mar 13 2021
A powerful springtime storm will continue to bring significant
moisture to western and north central Nebraska. Rain will
transition to snow in the northwest tonight, with the switchover
moving east throughout the day Sunday. Multiple aviation weather
hazards exist with this system, including low ceilings, strong
winds, heavy precip, and reduced visby. Expect continued IFR cigs
in the far west and south (KLBF), while conditions worsen tonight
north central (KVTN). East surface winds will gust to 30 kts
overnight and to 40 kts Sunday.
&&
.HYDROLOGY...
Issued at 257 PM CST Sat Mar 13 2021
The MBRFC ran a contingency forecast for the North Platte river
at North Platte which predicts a near bankfull rise to just below
action stage which is 5.5 feet. The forecast uses and expected
rainfall of about 2 inches. Model QPF plumes at this location
range from 2 inches in the 12z ECM to 4 inches in the down-scaled
NAM. WPC has responded by raising storm total rainfall to 2 to
nearly 4 inches with highest totals across ncntl Nebraska
including Custer county. Hourly rainfall rates of up to 1/4 inch
are likely tonight and Sunday. Wave after wave of moderate to
briefly heavy rain should occur with breaks in between. This will
likely lead to overland flooding in the valleys and low lands but
not flash flooding.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from midnight CST /11 PM MST/ tonight to 7
AM CDT /6 AM MDT/ Monday for NEZ005-023-094.
Winter Weather Advisory from 7 AM CDT /6 AM MDT/ Sunday to 7 AM
CDT /6 AM MDT/ Monday for NEZ006-008-024>026-035>037-057.
Winter Weather Advisory from 11 PM MST this evening to 6 AM MDT
Monday for NEZ022-056.
Blizzard Warning from 11 PM MST this evening to 6 AM MDT Monday
for NEZ004.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Snively
HYDROLOGY...CDC
Area Forecast Discussion
National Weather Service Mobile AL
929 PM CST Sat Mar 13 2021
.NEAR TERM /Now Through Monday/...Upper level ridging fades away
Sunday evening as an upper level trough swings negative and
occludes over the central Plains into western Great Lakes. As
this occurs, overall flow becomes westerly aloft through Monday.
Surface high pressure gradually shifts east with a general
pressure gradient setting up over the southeastern U.S. as low
pressure begins to weaken and move into Missouri on Monday. A
surface cold front moves into eastern Mississippi Monday morning
becoming stalled out and serving as better focus for convective
potential. The associated pressure gradient will promote
continued southerly flow over the region, and continue to
perpetuate warmer temperatures and higher moisture content across
the area. A couple of notable weather features are worth noting,
with most imminent being dense fog potential tonight, and the next
being a non-zero threat for severe weather on Monday afternoon
and evening. Both will be discussed below.
Dense fog will likely develop again tonight with overall regime
unchanged from last nights dense fog event. Expect fog to begin to
develop across coastal areas shortly after midnight tonight,
becoming more widespread and spreading inland through our coastal
counties in Alabama and the Florida Panhandle, as well as far
southeastern Mississippi counties during the overnight hours. A
dense fog advisory is in effect for this area through 10 AM CDT
Sunday. Dense fog will dissipate by mid to late morning, giving
way to partly to mostly cloudy skies. Morning temperatures in the
middle to upper 50`s will quickly rise once dense fog lifts, with
daytime highs topping out in the upper 70`s and lower 80`s for
most areas. Sunday night lows will be very warm with increased
cloud cover and increasing low level moisture, with lows in the
middle 60`s.
Now we get into the more uncertain part of the forecast with
Monday afternoon into evening. A low end chance for strong to
severe thunderstorms exists Monday afternoon and evening. The
aforementioned upper level trough and weakening surface low over
Missouri along with stalled frontal boundary over eastern
Mississippi stretching northeastward into central Alabama will
provide for some modest large scale ascent over our area. This
could foster the potential for shower and thunderstorm development
Monday afternoon. Modeled soundings suggest that a moderately
sheared environment will be present over the area, with general
consensus of near 30 to 40kts of sfc-6km shear, and curved,
elongated hodographs. In addition to this, it seems reasonable to
believe that MLCAPE values will be generally on the order of 500
to 1000 J/kg. It is important to note, however, that hi-res
guidance such as HRRR/NAM3KM support the higher range of MLCAPE
nearer 1000J/kg, with HRRR even upwards of 1500J/kg. Despite the
slight questions in CAPE, one persistent feature on forecast
models is the presence of a 700mb EML (Elevated Mixed Layer) that
could act as a cap that can limit convective coverage. This is
especially noticeable on the hi-res guidance, and unsurprisingly
they are rather meager on coverage of showers and thunderstorms
Monday versus the global models that have better coverage without
resolving the EML as clearly. All this considered, it seems
evident that the ingredients are present for potential strong to
severe thunderstorms, however to even realize that potential we
need sustained updrafts associated with deeper convection over the
area. For now, have opted to continue to keep chance to likely
PoPs over much of the CWA, with better chances over the northern
tier of counties in interior southwestern Alabama and interior
southeastern Mississippi where forcing is a little bit more
favorable for convection to fire in closer proximity to the
stalled surface front. IF more robust, sustained updrafts can
materialize, a low end potential for all severe hazards including
isolated instances of large hail, damaging winds, and even a brief
tornado are possible. This potential will continue to be monitored
as we move forward. Otherwise on Monday, anticipate afternoon
highs to top out in the lower 80`s for most locations, with upper
70`s along the immediate coast. Some patchy fog may be present
early morning but will quickly lift as southerly low level flow
increases with a tightening pressure gradient over the area. A
HIGH RISK of rip currents continues through Monday evening. MM/25
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...Dense Fog Advisory until 10 AM CDT Sunday for ALZ261>266.
High Rip Current Risk through Monday evening for ALZ265-266.
FL...Dense Fog Advisory until 10 AM CDT Sunday for FLZ201>206.
High Rip Current Risk through Monday evening for FLZ202-204-206.
MS...Dense Fog Advisory until 10 AM CDT Sunday for MSZ075-076-078-079.
GM...Dense Fog Advisory until noon CDT Sunday for GMZ630>636.
&&
$$
This product is also available on the web at:
http://weather.gov/mob
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
511 PM CST Sat Mar 13 2021
.SHORT TERM...(This evening through Monday Night)
Issued at 149 PM CST Sat Mar 13 2021
The main takeaway of the forecast is that the best chances for
snowfall remain the watch area, with the best chance for heavy snow
in the watch area near the Iowa/Minnesota border. Areas to the
northeast of the current watch, including the Twin Cities, have the
greatest uncertainty where there will still be a sharp cutoff.
Tonight and Sunday - high pressure will sag southward as the surface
low continues across Colorado. This will cause the westerly winds to
switch direction and become easterly overnight. The easterly winds
will increase into Sunday ahead of the next storm system.
Sunday night into Monday - The main impact in this period continues
to be the large system impacting the central CONUS. Little has
changed as the synoptic forecast of a large system with strong
moisture transport remains high confidence. The lower confidence part
remains how far north the QPF will go before the air dries out. As
the low moves east and occludes moist air will be transported farther
north into parts of the Upper Midwest. Model soundings in southern
Minnesota show a well defined dendritic growth zone favoring higher
snow ratios, although with the near freezing temperatures will
counteract that to suggest near climatology snow ratios.
One change since the previous forecast is a trend towards a slightly
later start Sunday night which greatly increasing the chances that
this will fall as all snow rather than rain near the start. The
greatest challenge with this forecast remains in the northern extent
of this precipitation. So where does the dry air win out and where do
the precipitable water values, as seen in many model soundings of
around 0.6 which is above the 90% for this time of year at MPX, lead
to notable QPF? Ensemble data like the NBM and GEFS suggest that the
best chances for accumulating snow remain south of the Minnesota
River where the moisture is more certain. Farther north between the
Minnesota River and I-94 there is much more variability between
ensemble members and deterministic models moisture transport. Some
guidance like the Canadian RDPS have little to no QPF in this area
while others like the RAP take it farther north and even into parts
of the southern Twin Cities metro area. On the ensemble side, GEFS
members at MSP range from 0.05 to 0.9 inches in accumulation
displaying continued high variability in the forecast here.
Looking ahead, much colder air arrives Monday as the snow ends which
will bring our streak of above average temperature days to an end
with highs in the 30s.
.LONG TERM...(Tuesday through Saturday)
Issued at 149 PM CST Sat Mar 13 2021
Tuesday into the next weekend - a warming trend returns with
temperatures back near normal by midweek and above normal by next
weekend. This warming trend is supported by the lack of snowpack and
warming ground temperatures such that once cold air masses move out
we can warm back to at or above average temperatures much quicker.
Tuesday into the end of the week is less certain on a precipitation
front. As there is another upper wave moving across CONUS right
behind Mondays system. Most deterministic and ensemble members
keep this to the south of the Upper Midwest right now, but the
interaction between the cutoff low from Mondays system and this
advancing upper wave mid-week adds some uncertainty to the forecast.
Bottom line: quieter weather most likely after Monday, but another
round of precipitation is still possible.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 500 PM CST Sat Mar 13 2021
Very little impacts during this TAF period with winds becoming
northeast/east during the next 6 to 12 hours, and gusty after 12z.
Most of the MVFR/IFR conditions will occur after 06z/15.
KMSP...
No additional concerns.
/OUTLOOK FOR KMSP/
Sun Night...VFR. Poss MVFR aft 09z. Wind E 10G20 kts.
Mon...MVFR/IFR, mainly aft 15z. -SN likely. Wind SE 10-15 kts.
TUE...MVFR cigs with IFR possible early. Wind Lgt and Vrb.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Winter Storm Watch from late Sunday night through Monday afternoon
for Blue Earth-Brown-Faribault-Freeborn-Le Sueur-Martin-
Nicollet-Redwood-Renville-Sibley-Steele-Waseca-Watonwan-Yellow
Medicine.
WI...None.
&&
$$
SHORT TERM...JRB/NDC
LONG TERM...NDC
AVIATION...JLT
Area Forecast Discussion
National Weather Service New York NY
957 PM EST Sat Mar 13 2021
.SYNOPSIS...
High pressure over the region will give way to an approaching
cold front late tonight. This cold front will move across during
the day Sunday, followed by high pressure from Sunday night
into Monday night. High pressure will then move out into the
Atlantic Tuesday into Tuesday night. Meanwhile, a weak wave of
low pressure will move off the Mid-Atlantic coast Tuesday night
into Wednesday. A larger area of low pressure approaches
Wednesday night and will move across Thursday night. The low
will move east of the region on Friday with a strong high
pressure area building in from the north and west going into
next weekend.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Forecast is on track with only minor changes needed to reflect
current observations.
High pressure will slowly give way to an approaching cold front
from the north and west. The pressure gradient will be weak
this evening and winds will be decreasing into late this
evening across the interior with a light breeze along the coast.
Winds will slightly increase late tonight into daybreak Sunday
as a cold front approaches from the north and west. Mostly
clear skies will continue through tonight and temperatures will
bottom out in the upper 20s across the interior to low to mid
30s closer to the coast and within NYC.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
A weak trough heads through the area on Sunday morning as high
pressure builds into the Great Lakes. Winds will shift northwest
and a pressure gradient again sets up across the region. A deep
mixed layer, up to about 4k ft, is also progged to set up by
mid morning as surface temperatures warm. This will increase the
potential for strong gusts, with model soundings indicating
near 50kts at the top of the mixed layer. HRRR 10m max wind
gusts are also suggesting 35-40kts over land, with 40-45kts over
the ocean waters. There is decent agreement amongst the models
that this is a late morning through later evening event, with
the strongest winds occurring mid afternoon Sunday. So, with
this in mind, have collaborated a Wind Advisory for the entire
forecast area starting at noon Sunday. The peak gusts will occur
in the mid to late afternoon, when momentum transfer is
maximized.
Increased cloud cover in the afternoon is also likely, with a spotty
shower possible across the interior as an upper trough swings
through to the north. Confidence is very low in any sprinkle
occurrence, however, given the depth the dry layer near the
surface.
Temperatures in the upper 40s and low 50s are expected with the
good mixing, even with a bit of cloud cover in the afternoon.
With the dry airmass in place with low RH values, gusty winds,
lack of any recent rainfall and favorable vegetation state, fire
weather concerns continue into Sunday for parts of the area.
See the Fire Weather section below for additional details.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
High pressure builds in from Southeast Canada Monday into
Monday night with ridging aloft. The ridge will be flattening
going into Tuesday and surface high pressure at that time will
be moving out into the Atlantic.
A series of shortwaves move across Tuesday night through
Wednesday. At the surface, a weak wave of low pressure will
approach from the west but will stay well south of the region.
The precipitation associated with the wave may reach far enough
north to get into the local forecast region Tuesday night into
Wednesday. Chance POPs were shifted more towards Tuesday night
with snow showers in the forecast. Slight chance POPs for rain
showers are in the forecast for Wednesday. Overall though, the
wave of low pressure is not expected to produce much
precipitation so any precipitation is expected to be light.
A weak pressure gradient resides over the area Wednesday before
another area of low pressure approaches. This will be a larger
area of low pressure with a deeper trough aloft associated with
it. The low pressure area and trough continue to approach on
Thursday and move across Thursday night into early Friday.
Slight chance POPs are also forecast for Wednesday and increase
to chance POPs for Thursday through Friday morning. Mainly a
rain event expected with possible mixing with snow on the
backside of the low on Friday with increasing cold air
advection. The precipitation could linger into Friday afternoon
so slight chance POPs are in the forecast for Friday afternoon.
A return to dry conditions is forecast for Friday night and into
next weekend as high pressure returns. A strong high will build in
from the north and west.
Regarding temperatures, below normal temperatures for highs are
expected Monday (low to upper 30s) and Tuesday (mainly upper 30s).
Temperatures forecast to rebound closer to normal values for
Wednesday (mainly upper 40s) and even slightly above normal Thursday
(mainly lower 50s) with slightly below normal values (mainly lower
40s) for Friday and next Saturday.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
High pressure weakens tonight as a deepening low moves into
Northern New England.
VFR through the period.
West winds 10 kt or less overnight. Winds will then turn back
to the northwest on Sunday with increasing speeds and gusts.
Expect gusts 25-30 kt during the morning and 30-40 kt by mid to
late afternoon. Gusts begin to diminish after 00Z Monday.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No unscheduled amendments expected tonight. Amendments may be
needed Sunday with start time of gusts and strength of gusts.
.OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY...
.Sunday night...VFR. NW 20-25kt with gusts 30-35kt in the
afternoon, diminishing throughout the night.
.Monday...VFR. NW 15-20kt.
.Tuesday...MVFR.
.Wednesday...MVFR early possibly becoming VFR late.
.Thursday...MVFR or lower in rain.
Detailed information, including hourly TAF wind component forecasts,
can be found at: http:/www.weather.gov/zny/n90
&&
.MARINE...
Winds are expected to continue to diminish tonight with high
pressure over the waters. This high will be giving way to an
approaching cold front late tonight. This cold front moves
across during the day on Sunday.
NW Gales are likely on all waters Sunday afternoon/night, with
sustained winds 20-30kts and gusts approaching 40kts. The peak
winds will occur Sunday afternoon, and as a result a Gale
Warning is in effect for all waters Sunday. Seas will build 4-7
ft across the ocean waters and 3-4 ft across the Sound on Sunday
afternoon as well.
Widespread SCA gusts Monday morning with possible gales on parts of
the ocean waters. SCA gusts expected on all the waters Monday
afternoon and just on the ocean east of Fire Island Inlet Monday
night, mainly during the evening. Then, wind gusts are below SCA
levels Tuesday through Thursday, with a return to SCA level gusts
forecast Thursday night.
For the seas, residual SCA seas on the ocean are forecast on Monday
with ocean seas below SCA thresholds thereafter until Thursday
late day and Thursday night, when ocean SCA level seas are
forecast once again.
&&
.FIRE WEATHER...
Sunday afternoon into the evening could also see min RH values
around 20-30% percent and NW winds gusting over 30 mph. As such,
and after coordination with WFO PHI and state partners, have
issued a Fire Weather Watch for northern NJ counties starting at
7am Sunday. With minimum RH values potentially increasing to
over 30% on Sunday afternoon, will continue to treat the
potential for enhanced brush fire spread with an SPS, elsewhere.
&&
.HYDROLOGY...
No hydrologic concerns are expected.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Wind Advisory from noon Sunday to midnight EDT Sunday night
for CTZ005>012.
NY...Wind Advisory from noon Sunday to midnight EDT Sunday night
for NYZ067>075-078>081-176>179.
NJ...Wind Advisory from noon Sunday to midnight EDT Sunday night
for NJZ002-004-006-103>108.
Fire Weather Watch from 8 AM EDT Sunday through Sunday evening
for NJZ002-004-006-103>108.
MARINE...Gale Warning from 6 AM Sunday to midnight EDT Sunday night for
ANZ330-335-338-340-345-350-353-355.
&&
$$
SYNOPSIS...JM/DBR
NEAR TERM...JM/JP/DBR
SHORT TERM...DBR
LONG TERM...JM
AVIATION...JP
MARINE...JM/DBR
FIRE WEATHER...
HYDROLOGY...JM/DBR
Area Forecast Discussion
National Weather Service Pueblo CO
353 PM MST Sat Mar 13 2021
.SHORT TERM...(This evening through Sunday)
Issued at 228 PM MST Sat Mar 13 2021
Upper low over the 4 corners region continues to send rounds of
rain/snow showers northward across the forecast area within the
warm conveyor belt region of the storm. Rain-snow line has been wavering
between 5000-6000 feet this afternoon. A quick 2 to 3 inches of
snow has been reported across the Pikes Peak region and southern
I-25 corridor as of early this afternoon. With another round of
snow expected to move into El Paso county shortly, this area could
end up with another 1 to 3 before 6 PM. Melting across the lower
elevations has limited accumulations some, but as we head into the
evening and temperatures cool...we should see some better
accumulations across southern El Paso county and eastern Fremont
county as the system crosses the mountains between 06z-09z and
pulls wrap around precipitation back southward into the northern
I-25 corridor and southeast mountains. Models keep slowing down
the upper low, and EC and 18z GFS pull the wrap around
precipitation farther south across the plains on Sunday as the
low deepens across southeast Colorado. So there is still some
uncertainty with how much additional snow will fall but forecast
generally looks on track and will keep highlights as is for now as
their is a chance that wrap around precipitation could be a little
heavier than what grids portray. Winds increase Sunday afternoon
so blowing snow will become more of a concern across northern El
Paso county as the day goes on though it looks like heavier
snowfall rates will be done by then, so strongest winds and
heaviest snow are not quite as well juxtaposed for blizzard
conditions.
As for severe thunderstorm potential across the far southeast CO
plains, this is looking less likely as the front has stayed well
south of the area with dew point recovery only in the upper 30s so
far. Latest HRRR keeps majority of stronger convection to the
south of the forecast area which looks reasonable. Given shear and
elevated thunderstorm possibility, can`t rule out a marginally
severe storm with some small hail possible...but risk for stronger
storms looks greatest to the south of the area. -KT
.LONG TERM...(Sunday night through Saturday)
Issued at 228 PM MST Sat Mar 13 2021
Precipitation still ongoing Sunday night across the plains and
Continental Divide region but may be shutting down across the
southeast mountains south of highway 50 a bit earlier as though EC
and NAM which split the difference in the divergent tracks of the
faster farther south GFS and farther north Canadian do hang on to
some snow until 06z. Given the differences in the models kept the
highlights unchanged for now. All highlights are set to come down
at 12z Monday as the upper low pulls off to the east.
Attention turns towards the next storm system which drops just
south of the 4 corners region on Tuesday and moves across northern
New Mexico Tuesday night. This system is more quickly moving but
its farther south track could actually bring more snow to the
plains than the previous one with its overnight timing and better
chance for rain/snow switch over across all of the lower
elevations of the plains Tuesday night. System could bring some
significant snow to the southeast mountains and Raton Ridge if it
maintains the more southerly track solution and potential for
northeast upslope flow. There are some track differences however
between the extended range models and with current storm still a
factor in the shorter ranges, will need to address these details
a bit later when things become more certain. For now grids are
carrying generally advisory snowfall numbers for the southeast
mountains and adjacent southern I-25 corridor in the
Tuesday/Tuesday night.
The weather dries out and warms up for the remainder of the work
week with another storm system moving through the western U.S. for
next weekend. -KT
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 228 PM MST Sat Mar 13 2021
IFR to LIFR conditions expected into the evening for KCOS and KPUB.
As the upper low crosses the mountains this evening winds will
shift out of the north for KCOS and KPUB with another round of
snow this evening through the overnight hours. IFR VIS/CIGs will
be possible through tonight with some improvement expected Sunday
morning for both terminals. Winds will increase on Saturday with
gusts up to 30-35 kts possible for KCOS and lighter gusts around
25 kts for KPUB. Could see another round of -SHSN though cigs
though northerly winds off the Palmer Divide may keep cigs more in
the MVFR range.
KALS will see generally VFR conditions with periodic -SHRASN
through the overnight hours. Cigs could briefly drop into the MVFR
range. Winds will increase out of the northwest on Sunday with
gusts to around 25 kts. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 6 AM MDT Monday for COZ058>063-
072>076-079>082-084.
Winter Storm Warning until midnight MDT Sunday night for COZ077-
078-083-085.
Winter Weather Advisory until 6 AM MDT Monday for COZ066-068.
&&
$$
SHORT TERM...KT
LONG TERM...KT
AVIATION...KT