Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/01/19
Area Forecast Discussion
National Weather Service La Crosse WI
550 PM CST Sat Nov 30 2019
.SHORT TERM...(This Evening through Sunday Night)
Issued at 231 PM CST Sat Nov 30 2019
Quite the weather system across the region at the moment, with an
impressive closed/stacked low and mid level circulation meandering
slowly east through Nebraska. That feature is expected to continue
an eastward jaunt the next 24 hours, eventually ending up over the
lower Great Lakes by midday Sunday, continuing to impact our region
with a myriad of weather conditions. First up, quite the PV
advection streamer ahead of the upper low continues to blossom an
axis of more widespread precipitation, in the wake of an earlier
return to mainly drizzle. Some thunder is occurring as that band
sweeps northeastward across the area with MUCAPE values spiking
to a rather impressive 200-500 J/kg (highest east of the
Mississippi River), with precipitation type a little tricky owing
to an initial loss of ice/warm nose aloft south of I-94 but
additional lift from any convective processes likely enough to
briefly overcome that warming and give more of a rain/snow/sleet
setup. Farther north is where the most concern lies (mainly
Clark/Taylor counties in our area) where strong lift and dynamic
cooling north of the upper low looks to result in mainly snow,
with a few hour period of heavy snow very much possible in that
convective band. Going forecast snow amounts already has this idea
messaged well, with not too many changes foreseen, save for
raising amounts across Clark County per near-term guidance trends,
where will upgrade the advisory to a warning.
Otherwise, looking like we will again lose the deeper moisture into
this evening as pronounced dry slotting arrives, even up to and
north of the I-94 corridor, suggesting a return to light
precip/drizzle is most likely at times for a few hours. Things
change again quickly after 02Z (per current trends) with a
tightening of the low/mid level temperature gradient north of the
low, with a subsequent uptick in 900-600mb frontogenetical
forcing, particularly near and north of I-90. That should help
force redevelopment of additional precipitation (tricky type
initially closer to I-90 given residual warm nose/loss of ice),
with deformation forcing kicking into gear late tonight into
Sunday driving a final axis of precipitation back south through
the area before ending Sunday evening.
As alluded to above, overall precipitation type(s) are somewhat of a
disaster to forecast through tonight given loss of ice at times and
periods of a more enhanced warm nose, particularly through this
evening. However, one bonus is that surface temperatures across much
of the area south of I-94 have warmed above freezing, helping
mitigate any freezing rain risk. Additionally, areas north of
Interstate 94 do look to remain primarily snow with plentiful ice
nuclei and any warm nose 1C or less, with 4 to 8+ inches of
additional accumulation expected, pending exactly where the axis
of heaviest precipitation "pivots" tonight. Farther south, we
should eventually erode the warm nose late tonight into Sunday,
with precipitation becoming all snow before ending. Envision a
swath of 1 to 3 inches generally near/north of I-90 and south of
I-94 during the late night and into Sunday, perhaps locally higher
should any bands line up over the same areas for longer, with
less than an inch farther south as forcing wanes quickly into the
afternoon.
As for headlines, will tack on Clark County, WI to the warning,
while also re-issuing an advisory for Monroe, Juneau, and Adams
Counties where the heavier snow band may pivot later tonight. May
eventually need to add additional counties farther west along I-90
with the potential for sloppy end of weekend/holiday travel into
tomorrow, but will allow later shifts to assess that need.
.LONG TERM...(Monday through Saturday)
Issued at 231 PM CST Sat Nov 30 2019
Quiet weather expected for the work week with seasonable
temperatures for early December. The region is mainly under Pacific-
influenced zonal to slightly northwest flow aloft with periodic
ridges and troughs crossing the region over the course of the week.
Low chances for snow return near the end of the period for northern
Wisconsin, but confidence in any details out that far remains low.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 550 PM CST Sat Nov 30 2019
RAP soundings continue to show that there will be no ice seeding
from aloft through much of the night, therefore, the surface
temperature will be the primary driver of the precipitation type
at the surface. Meanwhile aloft planes will have to deal with
icing. As the case through the afternoon, there may be brief
periods of ice pellets with any convection. In addition, there may
be some thunder along the wave lifting out of central Iowa.
However, there are some question in the RAP/HRRR whether it will
even get into the TAF sites.
Late tonight and Sunday morning, ice aloft returns with the
deformation band. This is when the snow will return. Snow at the
TAF sites will likely range between 1 and 3 inches.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from midnight tonight to 6 PM CST Sunday
for WIZ042>044.
Winter Weather Advisory until 6 PM CST Sunday for WIZ032>034.
Winter Storm Warning until noon CST Sunday for WIZ017-029.
MN...Winter Weather Advisory until 6 PM CST Sunday for MNZ079.
IA...None.
&&
$$
SHORT TERM...Lawrence
LONG TERM...Peters
AVIATION...Boyne
Area Forecast Discussion
National Weather Service Cheyenne WY
756 PM MST Sat Nov 30 2019
.UPDATE...
Issued at 749 PM MST Sat Nov 30 2019
Strong winter storm finally beginning to push east of the area
with slowly improving conditions this evening. Decided to cancel
most of the High Wind Warning and replace it with Winter Weather
Advisories since blowing snow is becoming the main hazard. Kept
the Blizzard warning going for far eastern Wyoming and the
northern/central Nebraska panhandle. Webcams, observations, and a
few spotters are still reporting blizzard conditions with blowing
snow and quarter mile or near quarter mile visibilities. Will give
this a few more hours and then consider downgrading to an Advisory
for blowing snow since the falling snow associated with the storm
has pretty much ended for the night.
Otherwise, kept the Blizzard Warning going for the wind prone
areas that are still receiving observing very low visibilities in
blowing snow with winds over 60 mph.
UPDATE Issued at 439 PM MST Sat Nov 30 2019
...Please see latest 0Z aviation discussion...
&&
.SHORT TERM...(This evening through Sunday)
Issued at 245 PM MST Sat Nov 30 2019
...POWERFUL WINTER STORM CONTINUES TO BRING BLIZZARD CONDITIONS
TO WESTERN AND NORTHERN PORTIONS OF THE CWA INTO TONIGHT...
Recent WV imagery and RAP analysis show the deep upper level low
continuing to push east over north-central Nebraska with a 988 mb
sfc low per mesoanalysis. This surface low will continue to
provide moisture to portions of the CWA before pulling off farther
east. Strong pressure gradients are present along with 60-70 kt
flow aloft from 800-700 mb resulting in strong winds and
widespread blowing snow across Southeast Wyoming and Western
Nebraska. Wind gusts observations along I-80 between Cheyenne and
Laramie have consistently been in the 55 to 70 MPH range all day.
Additionally, received numerous reports of power line damage in
the Nebraska Panhandle from strong winds. Blizzard conditions
began developing across the South Laramie Range and South Laramie
Range Foothills in Wyoming in addition to Banner County in
Nebraska. These zones were upgraded to Blizzard Warnings with the
morning update and have since met the 3 hour criteria. WYDOT and
NEDOT webcams have shown whiteout conditions with snow drifts
across many roadways. Other zones within the High Wind Warning
have seen significant blowing snow at times as well.
Falling snow seems to be wrapping up with the exception being the
eastern most counties in the CWA. Recent radar reflectivity shows
returns south of the Black Hills through Chadron where snow
reports of 1 foot were received this morning. Other sites farther
south through the Panhandle are still reporting snow where radar
is most likely overshooting bands of snow. An additional 1 to 3
inches may fall in these eastern zones. As snowbands continue to
push east this evening, stronger winds will move in over fresh
snowfall which will result in additional blowing snow over the NE
Panhandle. Winds will begin to decrease this evening, but will
still remain elevated into early Sunday morning as 50 kt winds
aloft will remain in place until then.
The current Winter Storm and High Wind Headlines continue through
5 AM MST Sunday. Hazardous travel will continue through the night
as slick/snow covered roads, reduced visibility in blowing snow,
and strong winds continue.
.LONG TERM...(Sunday night through Saturday)
Issued at 245 PM MST Sat Nov 30 2019
Upper level ridging will slide in in the wake of the strong sfc
low that that has brought snow/blowing snow and strong winds
across the CWA. Temperatures will begin to warm back to near
normal in the low 40s east of the Laramie Range and 30s west
starting Monday with mostly dry weather. Breezy winds will also
return Monday with an approaching shortwave and tightening
gradients. WRKBRX is around 50% with 50-60 kt westerlies at
700-800 mb. A cold front will move in from the northwest Monday
night which will bring the chance for snow across the higher
elevations, but only light accumulations expected at this time.
Afterward, zonal flow aloft takes over as a progressive shortwave
moves through the southern Rockies Thursday. Recent model guidance
has shifted this shortwave south so chances of precipitation with
this system seem unlikely. Looking towards week`s end, models
hint at our next large scale disturbance making its way into the
Pacific Coast, but plenty of model uncertainty with strength and
timing of the trough are present. 12z GFS currently pushes this
disturbance through relatively quickly while the 00z Euro digs the
trough farther south, potentially too far south for any
precipitation over our CWA. CPC`s 6-10 day outlook suggests above
normal temperatures and above normal precipitation heading into
next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 439 PM MST Sat Nov 30 2019
While ceilings across southeast Wyoming and the Nebraska Panhandle
are improving, visibility continues to be impacted by blowing
snow. Categories are down IFR and LIFR. Visibility will gradually
improve overnight west to east as high winds taper off. Flight
conditions will be much more favorable tomorrow especially after
18Z.
&&
.FIRE WEATHER...
Issued at 314 AM MST Sat Nov 30 2019
No fire weather concerns w/ deep snow pack already in place over
a large part of the area. Widespread snow & strong winds, along
with areas of blizzard conditions can be expected over the next 12
hrs.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Blizzard Warning until 5 AM MST Sunday for WYZ102-108-110-116-
117.
Winter Weather Advisory until 5 AM MST Sunday for WYZ101-106-107-
118-119.
High Wind Warning until 5 AM MST Sunday for WYZ106.
NE...Blizzard Warning until 5 AM MST Sunday for NEZ002-003-019-020-
095-096.
Winter Weather Advisory until 5 AM MST Sunday for NEZ021-054-055.
&&
$$
UPDATE...TJT
SHORT TERM...MB
LONG TERM...MB
AVIATION...CW
FIRE WEATHER...CLH
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1003 PM EST Sat Nov 30 2019
.UPDATE...
The first phase of mid level isentropic ascent produced a couple
rounds of radar returns across the Saginaw valley and Thumb during
the early to mid evening. The forcing and moisture supply slightly
overachieved compared to the newest model data and was still barely
able to reach the surface with some trace amounts of rainfall.
However, given the added moisture aloft, substantial erosion of the
low level dry air is occuring as suggested by the DTX 00Z sounding.
The sounding also shows elevated warm air solidly established in the
850 to 700 mb layer and reaching near +6 C at about 800 mb. Granted
there remains some wet bulb cooling that takes place as the first
round of significant moisture arrives but cross sections of RAP data
indicate the warm nose surging well north into the Saginaw valley
prior to sunrise at about +3 C to ensure complete melting of
hydrometeors. Freezing rain then remains the expected precipitation
type primarily along and north of the I-69 corridor with some leakage
south into northern Livingston, northern Oakland higher terrain, and
northern Macomb counties, although brief in these areas. Wet bulb
cooling potential is shown in late evening observations across the
area along with cold and dry air advection from southern Ontario.
Expect surface temperatures to settle into the 30-32 F range resulting
in high end advisory icing assuming no increase in liquid QPF that
averages 0.25 to 0.5 inch during the night. The QPF seems reasonable
based on plentiful coverage of convection indicated upstream along
with more than a handful of lightning strikes.
Some questions remain on additional precipitation type transitions
for the second surge of moisture set to peak during the morning hours
after sunrise. Forcing during this phase of the event is driven by
strong deformation within a large/high amplitude trowal that has all
the elements of outstanding vertical motion response. The occlusion
process appears to quickly displace the mid level warm nose eastward
resulting in a thermal profile supporting a change to snow around or
shortly after sunrise most likely along and north of M-46. The 00Z
runs of the NAM and RAP both offer additional QPF in the 0.25 to 0.5
inch range in the 12-18Z time period. This is likely a reflection of
the strong vertical motion response in convective instability on the
south flank of the trowal axis. Moisture availability is already well
established leaving uncertainty due to the actual position and
residence time of the precipitation axis. That being said, it is
possible higher additional snow accumulation could occur after
sunrise on top of any icing prior to sunrise which together could
require a headline upgrade for the Tri Cities and northern Thumb in
upcoming forecast updates.
&&
.PREV DISCUSSION...
Issued at 708 PM EST Sat Nov 30 2019
AVIATION...
A large low pressure system over the Plains moves into the Midwest
tonight presenting a wide range of aviation weather challenges for SE
Michigan tonight through Sunday. The first is ceiling trends during
the evening as strengthening easterly low level wind attempts to
erode stratus across the terminal corridor. The incoming dry air also
affects the onset of higher precipitation rate set to begin mainly
after midnight with some trace amounts possible during the evening.
Once underway, precipitation type ranges from all rain in the DTW
area to a wintry mix of freezing rain, sleet, and snow in the FNT
to MBS area. Increased precipitation rate and the approach of the
associated warm front lead a downward trend in ceiling and visibility
with IFR entrenched across the region by sunrise. Gusty east wind
tonight diminishes and becomes variable in direction Sunday morning
as the surface low slides across southern Lower Michigan. The track
of the system also leads to a decrease in precipitation from south to
north during the morning while borderline IFR/LIFR with drizzle and
fog holds along and north of the surface low. The DTW corridor likely
breaks out into low end VFR in SW flow Sunday afternoon.
For DTW... Breaks in low cloud coverage lead to fluctuation between
VFR and MVFR during the evening on a gusty east wind. Surface
temperature remains in the mid to upper 30s resulting in just rain
as coverage and intensity increase after midnight. The approach of
the low pressure system and leading pattern of rain both work to
return flight conditions to IFR by sunrise through Sunday morning.
DTW THRESHOLD PROBABILITIES...
* High for ceiling at or below 5000 feet tonight through Sunday.
* High for rain as precipitation type tonight and Sunday.
* Low for thunderstorms late tonight.
PREV DISCUSSION...
Issued at 340 PM EST Sat Nov 30 2019
DISCUSSION...
Occluding vertically stacked mid latitude cyclone centered over
eastern Nebraska late this afternoon will steadily eject east-
southeast over the next 36 hours, arriving at the MI/OH border
region by Sunday evening. Blossoming corridor of mid level warm air
advection tied to increasing southerly flow along the downstream
flank of this system will lift into lower Michigan tonight.
Meaningful saturation tied to early stages of the corresponding
isentropic lift met with some resistance locally through the evening
period, the resident dry profile held within easterly flow
continuing to define conditions outside of perhaps a few pockets of
light radar returns. Surface temperatures easing down into the lower
and middle 30s through this time.
A pronounced period of mid level forcing will emerge during the
early-mid morning hours, driven by favorable upper jet dynamics and
strengthening deformation engaging the inbound elevated warm frontal
slope. This will translate into a period of widespread precipitation
during this time. Diminishing deep layer stability given the
dynamics and high theta-e content will offer some heavier convective
bursts/possible thunder. Precipitation type ultimately defined by
both magnitude and northward expanse of the elevated warm nose,
working across a surface temperature that remains tenuously near or
just below freezing. The advective process expected to sufficiently
overwhelm the column for areas generally along/south of the M-59, so
any light wintry mix will be brief and confined to the early stages
as saturation/wet bulbing commences. A surface temperature still in
the vicinity of freezing will offer a several hour window for
freezing rain across the I-69 corridor (and perhaps far northern
Oakland/Macomb counties), before temperatures nudge above 32F.
Precipitation type transition and ice/snow accumulation potential
remains more complex across the Saginaw valley and northern thumb
region. An unsurprising mixed model signal on precipitation type
residence time over this corridor, owing to differences in the
strength of the warm nose at this latitude and influences of higher
precipitation rates on this warm layer. Meaningful precipitation
rates likely remain below 6 hours in duration, while a mixed phase
scenario places an additional ceiling on possible snow/ice
accumulation. Ice accretion efficiency will be aided by a firm
southeast wind gusting up to 30-35 mph, but perhaps muted too some
degree by marginal temperatures still in the 30 to 32 degree range.
This lends more confidence in witnessing advisory levels conditions
over this corridor.
Steady decline in precipitation coverage from southwest to northeast
through late morning as the cold frontal occlusion pivots through
and the attendant mid level dry slot takes residence. Substantial
component of low level moisture left behind ensures a cloudy and
dreary day. Some additional pockets of light rain or drizzle a
possibility as low level convergence increases beneath the mid level
cyclonic flow, but greater ascent currently projected to develop
across the Ohio valley during the latter half of the day. Broader
distribution in highs Sunday - mid 40s south to mid 30s north. Low
level flow backs to northerly upon the eastward exit of the upper
low, allowing colder air to funnel back in Sunday night.
Stretch of dry and cooler conditions will define the early week
period. Low stratus likely holds firm Monday within residual low
level thermal troughing. Any clearing as warm air advection
commences Monday night will then be replaced by thicker high cloud
Tuesday in advance of an inbound weak northern stream wave. This
wave will glance across the northern great lakes Tuesday night and
Wednesday. Moisture content will be lacking with this system, so
simply a low end potential for light snow/flurries mainly north
during this time.
MARINE...
With a slight southward deviation in the track from yesterday`s
forecast, stronger winds are a much higher possibility for southern
Lake Huron with gale force gusts likely tonight. Gale force gusts
still remain likely in northern and central Lake Huron with a period
of time Sunday morning of sustained gales possible. This increase in
wind strength is also due to the track change as north/central Huron
will remain in the cold sector of the storm creating a longer
duration unstable thermal profile.
For the nearshore zones, gales are likely for the Thumb and Saginaw
Bay through the night. Waves will remain elevated above small craft
advisory thresholds through Sunday, possibly into Monday. For Lakes
St. Clair and Erie, there could be a brief window of gale force
gusts late tonight into early Sunday morning. Waves will quickly
respond in those lakes with the east wind late this evening leading
to the small craft advisory starting at 3Z.
HYDROLOGY...
An area of precipitation will lift across southeast Michigan
tonight. The heaviest precipitation will occur during the early and
mid morning hours Sunday. A bulk of the precipitation will fall as
rain south of the I-69 corridor with a mix of snow, sleet, freezing
rain and rain further north. Precipitation will then taper off
Sunday morning as the system crosses the area. Total rainfall will
generally range between one half and three quarters of an inch.
Ponding of water in low-lying areas and rises on area rivers is
expected. However, widespread flooding is unlikely given the higher
permeability of upper layer soils which still have yet to freeze.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 10 AM EST Sunday for MIZ047>049-
053>055-060>063.
Lakeshore Flood Advisory until noon EST Sunday for MIZ049-055-063.
Lakeshore Flood Advisory until 7 AM EST Monday for MIZ048.
Lake Huron...Gale Warning until 10 AM EST Sunday for LHZ421-422-441>443-462>464.
Gale Warning until 10 PM EST Sunday for LHZ361>363.
Lake St Clair...Small Craft Advisory until 10 AM EST Sunday for LCZ460.
Michigan waters of Lake Erie...Small Craft Advisory until 10 AM EST Sunday for LEZ444.
&&
$$
UPDATE.......BT
AVIATION.....BT
DISCUSSION...MR
MARINE.......KDK
HYDROLOGY....MR
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion...Updated
National Weather Service Peachtree City GA
1000 PM EST Sat Nov 30 2019
.Update...
No changes planned for the forecast. Rain and a few thunderstorms
will gradually spread east and south across the area. There has
been a general weakening trend to the thunderstorms as they move
east.
41
.Previous...
.SHORT TERM /Tonight through Sunday Night/...
Main concern is the potential for strong/severe storms in NW and WC
GA after 9 PM tonight. Low level moisture increasing from the west
across AL today and faster than indicated by recent HRRR runs,
though there is substantial dry air over eastcentral GA. Concerned
that instability will be a tad higher than forecast. With HREF mean
0-1km SRH progged over 400 m2/s2 will be sufficient for a brief
tornado or two. Some HREF members also hinting that activity could
sneak into NW corner by 8 PM but more likely from 9 PM-midnight.
As line of convection spreads east, strong winds still possible it
should weaken as large scale forcing and environment (mainly
instability) become less favorable. Will likely see little or no CG
lightning except for a few strong cells before 3 AM. Line will move
through steadily and should be clear of the CWA by noon Sunday with
strong and gusty west winds. Could be close to advisory criteria,
but initial indications are it will remain below criteria.
As second shortwave dives into TN valley Sunday night, could see
some snow showers produce very light accumulations in elevations
above 2000ft. Surface temps have come in a bit colder than previous
guidance so have a little more snow showers than this time
yesterday. Accumulations will mainly be in grassy areas and less
than 1 inch. Roads should remain ice free as temps remain steady in
the lower 30s then climb to mid to upper 30s by noon Monday. Again
higher elevations will stay cooler with steep lapse rates and very
cold air aloft in this pattern. Will need to monitor for possible
advisory criteria in higher elevations.
SNELSON
&&
.LONG TERM /Monday through Saturday/...
The long term forecast picks up on Monday just as wrap around
moisture on the back side of a low pressure system will be passing
across northern Georgia with precipitation coming to an end. The
forecast area should remain dry through about early Friday when
the next system is expected to impact the area.
There are some disagreements between models for timing of another
upper level trough expected to impact the area Friday. The GFS
has a quicker progression east than the ECMWF leading to earlier
precipitation across the area early Friday. Have gone with a blend
for pops, bringing slight change to chance pops early Friday with
chances lingering through early Saturday. Models aren`t really
showing much instability with this system, so have continued just
chances for rain.
Monday is expected to be the coolest day of the long term forecast
with highs in the upper 30s and lower 40s across the north and in
the mountains with upper 40s and mid 50s across central Georgia.
Overnight lows into Tuesday morning will also be chilly with
widespread temps in the upper 20s and lower 30s expected across the
area. Temperatures will begin to moderate after that with highs
through the extended generally in the 50s and 60s with lows in the
30s and 40s.
Reaves
&&
AVIATION...
00Z Update... VFR conditions expected thru 06Z-09Z when line of
showers and some MVFR to near IFR cigs and vsbys move through.
Isolated thunder possible but chance too low to include in taf at
this point. Improvement expected shortly after precip moves out
after 14z. Winds will stay southwest 10 to 15kts then west and and
increasing to 12-16kts with gusts to 25+ kts after the line of
showers moves thru and persisting all day Sunday.
//ATL Confidence...00Z Update...
Medium on MVFR/IFR cigs tonight.
Medium-high on precip timing.
High on all other elements.
41
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 58 66 38 49 / 90 90 5 5
Atlanta 59 63 37 45 / 90 70 5 5
Blairsville 53 57 31 39 / 100 70 30 20
Cartersville 56 63 35 45 / 100 50 5 5
Columbus 63 68 40 51 / 80 80 5 5
Gainesville 58 63 37 46 / 100 70 5 5
Macon 59 69 40 51 / 60 80 5 5
Rome 55 61 36 45 / 90 30 5 5
Peachtree City 58 65 37 47 / 90 70 5 5
Vidalia 59 72 43 54 / 20 80 10 0
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...41
LONG TERM....Reaves
AVIATION...41
Area Forecast Discussion
National Weather Service North Platte NE
528 PM CST Sat Nov 30 2019
.SHORT TERM...(This evening through Sunday night)
Issued at 321 PM CST Sat Nov 30 2019
Wrap around light to moderate snow is expected to continue most of
the night across north central Nebraska and exit early Sunday
morning. The NAMnest model appears to have the best handle on the
snow wrapping through wrn and ncntl Nebraska. Much of the snow/snow
shower activity along Interstate 80 should dissipate around sunset
or early this evening.
The HRRR model and the consensus MOS plus bias correction was the
basis for the wind forecast tonight and Sunday. This suggested gusts
to near 60 mph this evening with speeds falling off after midnight;
especially where breaks in the overcast develop across swrn
Nebraska. The corridor of high winds across the srn Nebraska
Panhandle and swrn Nebraska should shift east toward ncntl Nebraska
tonight. The overcast skies across ncntl Nebraska tonight should
maintain a mixed layer with strong or high winds continuing. This
philosophy is backed up by the strong mixed layer winds shown by the
RAP model.
The short term model blend was the basis for the snow forecast
tonight and it indicates 1 to 3 inches this evening and overnight.
The Blizzard Warning will continue as wind speeds should increase as
the sfc low begins to pull away from wrn and ncntl Nebraska.
The temperature forecast overnight through Sunday night leans on the
bias corrected short term model blend which was cooler than the
deterministic short term model blend and the guidance blend. Lows
should fall into the single digits for a few hours tonight and
Sunday night. Return flow around a weak area of high pressure Sunday
night will likely limit radiational cooling effects.
.LONG TERM...(Monday through Saturday)
Issued at 321 PM CST Sat Nov 30 2019
A dry forecast is in place through 7 days. The upper level flow
will become mostly zonal sending Pacific high pressure into the
central Plains. The temperature forecast respects the snow cover
up north and highs in the 30s are in place along and north of
highway 20. Highs will warm into the 40s along and south of
Interstate 80. H850mb temperatures will be rising into the single
digits above zero Monday and beyond which should support highs in
the 40s where there is little or no snow cover.
The models show an arctic high pressure system dropping through the
nrn Plains and Midwest Thursday night next week. This system is
progressive and should move off east fairly quickly. Wrn and north
cntl Nebraska will on the "warm" or western side of arctic high and
30s to near 40 are in place for high temperatures Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 528 PM CST Sat Nov 30 2019
Blizzard conditions will continue through tonight for northern
Nebraska terminals (KGRN, KVTN, KANW, KONL) with IFR visby at
times. Scattered snow showers with brief visby drops will taper
late this evening for southwest Neb (KOGA, KLBF, KBBW), but cigs
remain MVFR. The very strong northwest surface winds will slowly
lessen overnight, but gusts will exceed 20 to 25kts for virtually
the entire forecast period. Low stratus clouds will begin to break
late morning to early afternoon Sunday, giving way to VFR.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 6 AM CST /5 AM MST/ Sunday for NEZ022-
026>029-035>038-056>059-069>071.
Winter Storm Warning until noon CST Sunday for NEZ007-010.
Blizzard Warning until noon CST /11 AM MST/ Sunday for
NEZ004>006-008-009-023>025-094.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Snively
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Morristown TN
810 PM EST Sat Nov 30 2019
.UPDATE...
EVENING UPDATE.
&&
.DISCUSSION...
An update will be issued to adjust PoP and Wx grids for the
slightly faster movement of showers and scattered thunderstorms
into the area. Elevated instability in the presence of strong QG
forcing will keep a chance of thunderstorms going through the
night. The main concern will be localized heavy rainfall that may
lead to some minor flooding problems. The southern portions of the
area may have the greatest potential for flooding over the next
few hours due to training cells.
DGS
&&
.AVIATION...
00Z TAF DISCUSSION.
Periods of rain will create highly variable conditions at the TAF
sites through the night. A line of showers and thunderstorms is
approaching from the west, and will cross the area between 00-06Z.
TS and IFR conditions may occur at the TAF sites with this line.
Predominany MVFR conditions are expected to follow but with IFR
possible at times. VFR conditions should return around 12Z behind
a cold front, along with an increase in winds and wind gusts, up
to 30 kts possible.
DGS
&&
.PREV DISCUSSION...
/ISSUED 307 PM EST Sat Nov 30 2019/
SHORT TERM (Tonight and Sunday)...
Complex weather occurring during the short term period. A large
vertically stacked cyclone is currently across the Great Plains
with a cold front across the Mississippi River Valley. Deep
southwesterly flow is ahead of this front resulting in isentropic
ascent across the forecast area. This is resulting in
unseasonably high moisture with HREF guidance placing 1.3 to 1.5
inch PW values across most of the forecast area, which is near
the maximum for this time of year. This, along with elevated
instability and a few embedded thunderstorms, will aid some
locally higher rainfall totals of 2 to 3 inches in spots while
most locations will remain in the 1 to 2 inch range. Temperatures
will also remain unseasonably warm tonight within the
southwesterly flow ahead of the front.
Strong winds will also be a factor tonight across the higher
elevations and adjacent foothills. This is not an ideal mountain
wave high wind event with the cyclone location and SSW wind
direction, but with the GFS, ECMWF, NAM, and RAP all in agreement
with a 50+ 850mb LLJ structure across the TN Valley and Southern
Appalachians, believe there is a high likelihood of at least 50 to
55 mph winds across the higher elevations, including the US 441
corridor. There is also a strong pressure differential across the
mountains which will increase the probability for some wave events
and associated higher winds in the adjacent foothills. For this
reason, have issued a wind advisory for the higher elevations of
the mountains along the TN/NC border. This will need to be
monitored tonight and may need to be upgraded to a warning if
conditions warrant.
A majority of the precipitation moves east on Sunday with drier
air advecting into the area on Sunday morning behind the cold
front. The air behind the cold front will not be very cold, but
will actually be near normal for this time of year. A secondary
cold front will bring much colder air to the region Sunday evening
and into the overnight hours.
JB
LONG TERM (Sunday night through Saturday)...
The center of the low pressure system that impacts the forecast
area this weekend shifts east southeast out of the Upper Ohio
Valley across the Middle Atlantic Coast and out to sea through the
first 36 hours of the long term. Model forecasts are resolving
the system a little better, showing a brief period of deeper
moisture and lift late Sunday night into Monday morning for some
likely and categorical pops for mainly Southwest Virginia and
Northeast Tennessee. Precipitation will be primarily in the form
of rain as the event begins, but enough cold air will be building
into the region; especially above two thousand five hundred feet
for the light rain to change over to some light snow. Across lower
elevations over much of the remainder of the forecast area, low
level temperatures will stay just above freezing, so the light
rain will be mixed with some light snow with very limited
accumulation expected. However, in the higher terrain there will
be some light accumulation which may last well through the day
Monday while fading from south to north through Monday night. In
the cold air advection, northwest flow pattern typical with a
system like this, snowfall will accumulate with in the higher
terrain across Southwest Virginia and Northeast Tennessee
southwest through the Smoky Mountains. In these areas, snowfall
amounts could be in the one to three inch range, with locally
higher amounts possible during the 36 hour period ending at 12z
Tuesday morning. Following the departure of this system, the
forecast area may be able to squeeze out a few hours of sunshine
on Tuesday before the next upper trough drops southeast out of
Canada. This system still looks a little moisture starved and
relatively weak for the possibility of precipitation, so
maintained a mid week dry period. The American and European models
are still not entirely on the same page with a late work week
southern stream feature that has a surface reflection tracking
well south of the forecast area. Strongest lift and better
moisture still appears to be farther south across the Deep South
region with this short wave. However, there will be some
isentropic ascent north of the surface low and there could be just
enough moisture ahead of another cold front associated with a
northern stream wave building through the Eastern Great Lakes and
Northeastern U.S. at this time for some light rain, so kept this
concept going late Thursday night into Friday. Due to model
differences with the progression of a deepening Western U.S.
trough at the end of the long term forecast on Saturday, stayed
with a dry forecast while awaiting better model resolution.
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...Wind Advisory from midnight tonight to 7 AM EST Sunday for
Johnson-Southeast Carter-Unicoi.
Wind Advisory until 7 AM EST Sunday for Blount Smoky Mountains-
Cocke Smoky Mountains-Sevier Smoky Mountains-Southeast
Greene-Southeast Monroe.
VA...NONE.
&&
$$
Area Forecast Discussion
National Weather Service Mount Holly NJ
948 PM EST Sat Nov 30 2019
.SYNOPSIS...
Low pressure will move from the plain states towards the lower
Great Lakes tonight into Sunday. A secondary low is expected to
develop in Virginia, Maryland and Delaware by late Sunday. The
secondary low is anticipated to intensify as it moves slowly to
the northeast, reaching Nova Scotia on Tuesday afternoon. High
pressure should gradually build into our region from the west
and southwest during the balance of the work week. A cold front
may approach from the northwest late on Friday.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
No big changes to the forecast so far this evening. The overall
trend looks good. We have made some hourly temperature and
dewpoint adjustments, but the overall forecast still looks good.
Precipitation will begin to move into portions of southeast
Pennsylvania, southern New Jersey, Delaware and eastern Maryland
around or shortly before daybreak. Delaware and Maryland,
should remain mostly above freezing and be all rain, except
possible the extreme northern portions of Cecil and New Castle
counties where a brief period of freezing rain or sleet may
occur before warming up. The same is expected for southern New
Jersey where temperatures are currently below freezing.
Temperatures are expected to rise late in the night just before
precipitation begins. So if there is any freezing rain or sleet,
it is expected to be brief. So the advisory was not adjusted at
this time. The more likely areas for freezing rain to occur is
farther north across Pennsylvania and central/northern New
Jersey. Precipitation likely will not begin for central/northern
New Jersey and northeast Pennsylvania until after daybreak.
However, portions of southeast Pennsylvania is expected to have
precipitation move into the area shortly before daybreak when
temperatures will remain below freezing. Therefore the
advisories remain in place where they area.
This will just be the very beginning though and for further
details please see sections below.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
Sunday-Monday... The storm arrives. A complex, two-phased winter
storm remains on track to impact the area. There have not been any
big changes in the overall forecast thinking, with just typical
adjustments to the forecast based on latest trends and thinking. I
do want to break down headline decisions, however, as it is a
complicated situation in that regard.
A Winter Storm Warning has been issued for portions of northern New
Jersey and the Poconos. This covers the entire expected storm
duration to cover the anticipated combination of snow, sleet, and
freezing rain.
There are two tiers of Winter Weather Advisories in effect. The
southern tier, covering southeast Pennsylvania including
Philadelphia, has been issued to cover the potential for a period of
snow, sleet, and freezing rain Sunday morning, and it expires early
Sunday afternoon. The northern tier of advisories covers some
additional zones to the northeast, and that advisory is in effect
for the entire duration of the storm, as wintry impacts are expected
to continue through the day Monday due to the second period of
steady precipitation. That advisory may need to be expanded
southward in future updates once the first phase of the storm is out
of the way, and if snow amounts for Monday were to increase then
portions of it could be upgraded to a warning.
Otherwise, still looking at a very complex, two-phased winter storm
affecting the area as occluding low pressure over the Midwest
redevelops offshore.
Phase One, Sunday morning through evening: This will be the
overrunning precipitation phase as we get into a southerly flow WAA
regime with the weakening parent low to our west and the secondary
low developing along our coastline. Due to wet bulbing effects, many
areas even along I-95 will likely start at least briefly as snow,
sleet, or freezing rain. A quick change to rain is likely inside of
I-95, but signals remain strong for a prolonged mixed precip event
across the interior. High pressure centered to our north over Quebec
is in a fairly classic position to lock in low level cold. Ptype
remains a bit of a question mark. Have been fairly bullish on sleet
potential versus snow or fzra. Today, some guidance has trended
towards more fzra, though most forecast profiles to me still look
more supportive of mostly sleet. The 30.12z RGEM looked reasonable
to me, and as that tends to be a reliable model anyways I leaned on
it pretty heavily, with some blending of the NAM and other hi-res
guidance. Some of our northernmost zones will also stay as all snow
for a time Sunday, and some hi-res guidance such as 30.18z HRRR
would suggest my snow amounts up north tomorrow are too low. But
will let a fresh set of eyes reevaluate. QPF on Sunday is fairly
impressive for an overrunning event as the dynamics are on the
strong side. Given expectations for temperatures to remain below
freezing most of the day in the interior, it will likely be a very
messy day in northern and western parts of the area regardless of
exact ptype, as any combination of steady precipitation and below
freezing temperatures creates hazardous conditions. As overrunning
precip lifts north and secondary low pressure development continues,
a lull in precipitation is expected Sunday evening. Some lingering
showers or drizzle remain possible during this time, and there could
be continued light freezing rain or freezing drizzle in our northern
zones during the evening.
Phase Two, late Sunday night and Monday: This is where the
uncertainty remains higher. Signals remain for a band of snow,
potentially heavy and also potentially enhanced by an inverted
trough, to impact northern parts of the area. There is considerable
spread in how strong that band will, where it will focus itself, and
how far south it will make it. But a transition from rain or
freezing rain to snow is likely late Sunday night or Monday morning
in the northern portion of the area, and there remain indications
for the potential of several inches of snow especially in the areas
where the Winter Storm Warning is in effect. Again, some changes are
likely for this time especially if the main band of heavy snow ends
up being both as strong and as narrow as some models suggest. But it
is too early to begin creating the sharp snowfall gradients
associated with pinning down such a band.
**Summary/Key Points**: Travel across the interior is likely to
be very difficult on Sunday, especially as it is already a busy
holiday return travel day. While ptype remains somewhat
uncertain, am fairly confident that much of the day will
feature steady precipitation with sub-freezing surface
temperatures, which is always going to cause problems on the
roadways. Lesser but non-zero impacts are possible in the
morning as far southeast as I-95. For Sunday night and Monday,
there remains some uncertainty in the forecast. However,
several inches of accumulating snow and associated travel
impacts remain likely across portions of northern New Jersey
and eastern Pennsylvania. Users should continue to closely
monitor the forecast.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
By Monday night, uncertainty remains a bit high on the evolution of
precipitation and amounts. However, it does appear that wrap around
precipitation amid deformation banding will be transitioning quickly
from rain to snow from north to south Monday evening. Guidance
differs on intensity and accumulation of precipitation, however
I was confident enough to include likely PoPs across the
northern tier for the evening and early overnight. Precipitation
is forecast to move completely out of the forecast area by
daybreak on Tuesday.
I made some minor adjustments to the snowfall forecast during this
time. If the forecast trends more in the direction of the 12Z ECMWF,
would likely get a few inches of snow down across central and
northern NJ including the northern Shore as the band exits, but
changes in the forecast are likely during this forecast period
so we did not include any headlines for these areas at this
time. Heavier snow is still forecast across the areas where the
Winter Storm Warning has been issued, so this headline will
cover this activity. Went a bit colder than guidance for Monday
night and Tuesday given ongoing snow and snow cover across the
north.
Please continue to monitor changes to the forecast during this
period as accumulating snowfall is forecast as the long duration
winter storm departs the region, but uncertainty remains.
Did not focus much attention on the periods beyond Monday
night, but blended in a bit of the latest consensus guidance.
Previous discussion follows...
We should remain in a cyclonic flow pattern for Wednesday into
Thursday. As a result, there may be some stratocumulus overhead at
times, with a passing sprinkle or flurry possible. Daytime highs
should favor the 40s, with readings not getting above the 30s in the
elevated terrain.
A cold front is expected to approach from the west on Friday.
However, any precipitation associated with the front should not
arrive until late in the day.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Tonight... Mostly VFR with lowering cigs from S-N after
midnight. Winds remaining 5-8 knots or less but shifting from
N/NW to NE through this evening and then E/NE by morning.
Sunday... MVFR-IFR conditions expected with primarily rain at
MIV and ACY. A mix of rain, sleet, and possibly freezing rain
at northern terminals (particularly RDG and ABE). The MVFR
conditions should set in through the morning with IFR arriving
around midday. Easterly winds around 10 kts. High confidence
winds and flight categories, moderate confidence in
precipitation types. Confidence is increasing that the I-95
terminals will experience at least a couple hours or more of
freezing rain and sleet before changing to rain, especially PHL
northward.
OUTLOOK...
Sunday night...IFR conditions with periods of rain. The rain is
expected to transition to a wintry mix at KABE and KRDG after
midnight. Winds remaining around 10 knots but shifting from NE
to NW. Medium confidence.
Monday...IFR with mainly snow at KABE and KRDG. Mainly IFR with
rain changing to snow at our remaining six TAF sites. There
could be brief periods when conditions improve to MVFR during
lulls in precip. An accumulating snow is possible, especially
at KRDG, KABE and KTTN. Northwest wind increasing to 10 to 15
knots. Medium confidence.
Monday night...Snow ending with conditions gradually improving
from to VFR. Northwest wind 10 to 15 knots with gusts around 20
knots. Medium confidence.
Tuesday...VFR. Northwest wind 10 to 15 knots with gusts around
20 knots. Medium confidence.
Tuesday night...VFR. West wind 5 to 10 knots. Medium confidence.
Wednesday...VFR. West wind around 10 knots. Medium confidence.
Thursday...Mainly VFR with NW winds around 10 knots. Medium
confidence.
&&
.MARINE...
Tonight...Sub-SCA conditions expected. East winds around 10 kts
and seas 1-2 feet.
Sunday...SCA conditions developing across all ocean waters
throughout the day. Easterly winds will be gusting up to 25 kts
with seas building to around 4-5 feet later in the day. Gale
force wind gusts possible north of Barnegat Light late in the
afternoon and early evening as the center of low pressure moves
offshore and rapidly intensifies. Waves will be higher in these
areas. Issued a Gale Watch for this period.
OUTLOOK...
Sunday night...Marginal SCA conditions will persist through the
overnight with west to northwesterly winds gusting 20-25 kts and
waves 4-7 feet.
Monday through Tuesday...Northwest winds gusting to around 25
kts and waves 4-6 feet. Confidence on SCA conditions is highest
overnight Monday night when wind gusts may reach up to 30 kts.
Tuesday night through Thursday...Conditions are forecast to
remain below SCA criteria.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Winter Storm Warning from 4 AM Sunday to 1 AM EST Tuesday for
PAZ054-055.
Winter Weather Advisory from 4 AM Sunday to 1 AM EST Tuesday
for PAZ061-062-105-106.
Winter Weather Advisory from 3 AM to 1 PM EST Sunday for
PAZ060-070-071-101>104.
NJ...Winter Storm Warning from 4 AM Sunday to 1 AM EST Tuesday for
NJZ001-007-008.
Winter Weather Advisory from 4 AM Sunday to 1 AM EST Tuesday
for NJZ009-010-012-015.
DE...None.
MD...None.
MARINE...Small Craft Advisory from 10 AM Sunday to 1 AM EST Monday for
ANZ452>455.
Gale Watch from Sunday morning through late Sunday night for
ANZ450-451.
&&
$$
Synopsis...Fitzsimmons
Near Term...Fitzsimmons/Robertson
Short Term...O`Brien
Long Term...Iovino/Staarmann
Aviation...Fitzsimmons/Staarmann
Marine...Carr/Iovino/Staarmann
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Sunday)
Issued at 341 PM CST Sat Nov 30 2019
As of 21Z, water vapor imagery showed a tight cyclonic circulation
near the Nebraska and South Dakota state line. This strong storm
system brought rain and thunderstorms to the area last night and
is providing gusty winds across the region today. Some locations
in north-central Kansas were gusting to near 50 mph as of mid
afternoon. Winds will continue to increase this evening and
overnight in response to a tightening pressure gradient over the
area as the storm system pivots into Iowa. A 50 to near 60 kt LLJ
will set up over the area tonight. RAP forecast soundings show
mixing to near 850mb through most of the night, which could allow
those higher winds to mix down toward the surface. The strongest
winds are expected to occur where the pressure gradient will be
greatest, mainly over north-central and far northern Kansas. As
such, the High Wind Warning continues for north-central Kansas
until 15Z Sunday where sustained winds will be between 30 and 40
mph with gusts to near 60 mph possible. The rest of the forecast
area will be in a Wind Advisory until 15Z Sunday with sustained
winds between 25 and 35 mph with gusts to 50 mph possible.
There will also be a chance for light rain/snow, or even a light
wintry mix for areas near and north of Interstate 70 tonight in a
zone of wrap-around precipitation. Impacts are expected to be
minimal since QPF will be very light.
Cloud cover will stick around into tomorrow afternoon but conditions
will be dry. Winds will begin to subside during the late morning
hours as the pressure gradient relaxes. CAA and cloud cover will
limit temperatures to the 30s tomorrow.
.LONG TERM...(Sunday night through Saturday)
Issued at 341 PM CST Sat Nov 30 2019
The long-term portion of the forecast period is looking fairly
settled, with only one system that could bring precip back to the
region.
Upper level ridging and surface high pressure will work into the
area on Monday. Ridging will allow temperatures to be near
climatological normals (mid 40s for highs and upper 20s for lows)
under sunny skies. An upper level shortwave will move over the
region on Tuesday but no precip is expected with that system.
Surface winds will shift from the southwest to the northwest, but
temperatures are expected to warm into the 50s with no evidence
of CAA occurring in response to northerly winds.
From midweek into late week, an upper low will traverse the
southern tier of the country. That system will pass south of the
area on Thursday, bringing our next potential chance for
precipitation. Models are indicating dew points returning to the
40s in eastern Kansas ahead of the system. There may be enough
lift to allow for light precipitation in eastern Kansas and both
the Euro and GFS show at least light QPF across the southern CWA.
Otherwise, conditions will remain fairly quiet into the start of
next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 531 PM CST Sat Nov 30 2019
Strong west to northwest winds of 20 to 30 kts with gusts of 40 to
50 kts persist through the overnight hours, gradually subsiding
through the day on Sunday. MVFR to low VFR stratus work through
much of the area tonight through Sunday, with light rain/snow
mainly north of the TAF sites before sunrise tomorrow.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 9 AM CST Sunday for KSZ009>012-021>024-026-
035>040-054>056-058-059.
High Wind Warning until 9 AM CST Sunday for KSZ008-020-034.
&&
$$
SHORT TERM...Teefey
LONG TERM...Teefey
AVIATION...Skow
Area Forecast Discussion
National Weather Service Las Vegas NV
720 PM PST Sat Nov 30 2019
.SYNOPSIS...Considerable cloudiness will spread across the region
ahead of another Pacific System that is expected to mainly impact
the central and northern Sierra Sunday and Monday. This system will
move inland and bring chances of precipitation to much of our area
by Wednesday then move away by Thursday for a brief dry period
followed by more unsettled weather next weekend.
&&
.UPDATE...Shallow wedge of warm air advection captured on our Vegas
afternoon sounding providing enough lift for continued area of light
stratiform rain across the western Mojave Desert and Morongo Basin
this evening. As warm air advection weakens, HRRR and 00z NAM
indicate light precipitation receding back westward into the
Tehachapis and southern Sierra late tonight through Sunday. Guidance
still shows narrow plume of moisture associated with higher rainfall
rates remaining aligned from just south of Monterey Bay
northeast into the Tahoe Basin Sunday night into Monday. Am not
expecting any heavy rainfall over the snow cover at the Taboose Burn
Area in Inyo County. Tweaked our POPs across San Bernardino County
for the rest of tonight, no other changes.
&&
.PREV UPDATE...352 PM PST Sat Nov 30 2019
.UPDATE...Light rain falling as far east as Barstow this afternoon.
Updated our grids to increase POPs across the western Mojave Desert
of San Bernardino County. No other changes at this time.
&&
.DISCUSSION...Considerable mid and high clouds will spread
across our region and produce a dense overcast this evening and
overnight, but precipitation will be largely intercepted in
California by the coastal ranges and Sierra. Our southern Sierra and
Owens Valley zones will see the potential for some light snow, but
most of the precip will occur west of the Sierra Crest. The broad
closed low off the northern California Coast that was directing a
long plume of subtropical moisture into California should keep the
associated atmospheric river oriented toward central and northern
California Sunday and Monday with only light precip possibly
spilling over into the Owens Valley. Cold air trapped in the Owens
Valley should result in snow tonight though snow levels will be
rising to above 7000 feet Sunday into Monday. The potential for
freezing rain Sunday night and Monday night is not out of the
question, but a deep layer of cold air in the Owens Valley may
result in refreezing of any melting precip into ice pellets.
Something to keep a close eye on.
There is good agreement among the models that the eastern Pacific
System will dig toward southern California Tuesday then moves fairly
quickly inland Tuesday night and Wednesday. However, there is still
some uncertainty in timing and track. Either way, much of our region
will likely see another round of precipitation with any particular
site probably in a 6-9 hour window of precipitation. Any snow
accumulations will generally be at elevations above 6000 feet. The
system is forecast to pull away quickly Wednesday night followed by
generally dry conditions Thursday. A large eastern Pacific trough
approaching the coast will then bring chances of precipitation back
into the forecast area late Friday into Saturday.
&&
.AVIATION...For McCarran...Light and variable wind expected to
continue through tonight and tomorrow, favoring typical diurnal
directions. Increase in cloud cover and lower ceilings are expected
through this evening. Ceilings should remain SCT-BKN aoa 8-10 kft.
For the rest of southern Nevada, northwest Arizona and southeast
California...Mostly light and variable winds expected across the
region through today and tomorrow. Some breezy southeast winds are
possible at KBIH this afternoon through the overnight period
accompanying vicinity snow showers, but should generally remain
below 10-15 knots. Best chance of seeing snow showers at KBIH will
be early tomorrow morning, mainly after 12-15Z. Visibility and
ceilings will decrease with these snow showers with visibilities
dipping as low as 4SM at times and BKN to OVC ceilings aoa 6-8 kft.
Elsewhere will remain dry with increasing to mid to high clouds. &&
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
UPDATE...Pierce
DISCUSSION...Adair
AVIATION.....Kryston
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