Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/05/17
Area Forecast Discussion
National Weather Service Taunton MA
1000 PM EST Sat Mar 4 2017
.SYNOPSIS...
Arctic air mass accompanied by very brisk winds will bring
bitterly cold wind chills to the region tonight. A significant
warming trend follows, with temperatures likely back into the
50s Tuesday and Wednesday, along with some rain showers at
times. Mainly dry but colder weather returns Wednesday night and
Thursday. Forecast confidence becomes quite low Friday into
next weekend, but appears a decent shot for unsettled weather at
times.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
10pm update...
Forecast on track for the most part. Temp decrease a little
slower than previously forecast, so will adjust for that toward
latest short-term guidance, but the end result is the same, so
no need to adjust wind chill headlines. Otherwise, forced all
POPs offshore of Cape Cod as the window of influence is
generally closing at this time.
Previous discussion...
Tonight...Main issue over land is expected to be wind chill due
to the combination of a very cold air mass, one of the coldest
of this season, and a tight NW pressure gradient. Even with the
wind mixing, temperatures across the northwest interior may
reach 0 to 10 below and in the 0 to 10 above range across the
rest of the area outside of the Cape and Islands. This is
especially impressive given the lack of a snow cover.
The only precipitation risk is just a slight chance of snow
showers grazing the outer Cape as low level winds turn slightly
more northerly. Confidence is low since the surface gradient
becomes slightly more anticyclonic and subsidence may tend to
inhibit band formation as far west as the Cape. Latest HRRR
keeps snow bands offshore.
Models depict a 35 to 40 knot low level jet across the area
tonight at 925 mb. Although not all of that will mix to the
surface, still expect to have gusts persisting into the 20 to 25
knot range across exposed terrain and the near the coast.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Sunday...This period should be dry and sunny with some
moderation of temperature after a very cold start. Anticipate
high temperatures to reach the upper 20s to around 30, which is
still below normal for this time of year. Winds will be somewhat
brisk but there will not be the gradient to support winds as
strong as today. Most gusts will probably be in the 20 to 25
knot range.
Sunday night...This period should be clear and dry. With a ridge
of surface high pressure reaching New England, winds should
become very light and allow for efficient radiational cooling.
The air mass begins to moderate but that will be at least
partially offset by the radiational cooling. Even colder
temperatures would result if we had snow cover. Even with a lack
of snow cover, we anticipate temperatures reaching 0 to 5 below
across NW Massachusetts and in the 0 to 10 above range for much
of the rest of interior southern New England.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Highlights...
* Dry Monday with moderating temperatures inland from the coast
* Mild Tue/Wed with some rain showers at times
* Mainly dry, but turning colder Wed night/Thu
* Unsettled weather possible at times Fri into next weekend, but
precipitation types/temperatures are highly uncertain
Details...
Monday...
Still appears that high pressure will move east of southern New
England during the day. With fairly light winds, expecting slightly
above normal temperatures to return for most of the region. There is
some question whether winds become light enough for seabreezes to
develop, which would be a big deal temperature-wise along the coast.
Even so, water temperatures were close to normal high air
temperatures for this time of year.
Monday night and Tuesday...
An intensifying low pressure moves north from the Dakotas into
central Canada. This track will first push a warm front past our
region Monday night, leading to well above normal temperatures
Tuesday. Dry weather should give way to an increasing risk for
showers from late Monday night into Tuesday afternoon. Depending
upon the exact timing, there is still a window for a period of
freezing rain or sleet late Monday night. Expecting most of the
precipitation to fall as rain during Tuesday.
Tuesday night and Wednesday...
Cold front probably crosses the region Tuesday night into early
Wednesday morning, which will be the period with the greatest risk
for rainfall. Dry weather will probably dominate by Wednesday
afternoon, and the cold air will lag behind this front. Still
thinking above normal temperatures for Wednesday.
Wednesday night and Thursday...
Mainly dry weather follows in the wake of a cold front, but still
cannot rule out a spot rain/snow shower or two. Colder weather will
return with high temperatures back to near normal levels Thursday.
Friday into Next Weekend...
This remains the period of lowest confidence in the forecast. It`s
about this time that differences back on Wednesday amplify to the
point which become significant late next week. 04/12 GFS is
definitely the warmest solution, while the ECMWF solution opens the
door for the possibility of some snow Saturday night. With over 100
dam spread in 500 mb heights during this time in the GEFS, lots of
uncertainty remains. For now, will continue to mention a chance of
rain and/or snow. It appears likely these differences will not get
resolved until sometime in the middle of next week.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight and Sunday...High confidence. VFR expected. Only
exception could be pockets of MVFR CIGS across the outer Cape,
which could be grazed by ocean effect snow bands tonight. NW
winds will continue to gust between 20 and 30 kt tonight, and
generally gusting to 20 to 25 kt Sunday before diminishing late
in the day.
KBOS TAF...High confidence in TAF.
KBDL TAF...High confidence in TAF.
Outlook /Monday through Thursday/...
Monday...High confidence. VFR.
Late Monday night into early Wednesday...Moderate confidence.
Periods of MVFR-IFR conditions likely in low clouds/fog patches and
some rain showers.
Wednesday afternoon through Thursday...Moderate confidence. Return
to mainly VFR conditions.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Extended the Gale Warning for Boston Harbor a few more hours.
Latest observations still showed frequent gusts too close to 34
kt for comfort. Issued a Small Craft Advisory for Narragansett
Bay to take the place of the expiring Gale Warning. This will be
the general trend overnight: Gale Warnings downgraded to Small
Craft Advisories for most of the near shore waters. Its just a
question of timing. Will adjust the marine headlines overnight,
as conditions dictate.
Previous discussion...
Winds and freezing spray remain the issues for the short term.
Extended the Boston Harbor and Narragansett Bay Gale Warning to
7 PM. Have continued the Gale Warning over the other waters as
previously indicated. For those marine zones where the Gale
Warning expires, we will need to post a Small Craft Advisory,
which will probably last through much of Sunday. The Freezing
Spray Advisory remains in effect tonight for most of the waters
where we anticipate with fairly high confidence a number of
hours of moderate freezing spray.
Winds should gradually diminish Sunday. Our mixing tool suggests
wind gusts over most waters 25 to 30 knots during Sunday morning
and 20 to 25 knots during the afternoon before diminishing
further toward sunset.
Outlook /Monday through Thursday/...
Monday...High confidence. Northwest wind gusts and seas diminish
across the waters as high pressure builds in from the west. Winds
should turn south to southwest Monday night.
Tuesday and Wednesday...Moderate confidence. High pressure moving
east of the waters, coupled with strong low pressure lifting well to
our northwest, will result in an increasing south to southwest flow
of air. Wind gusts approaching 30 kt are expected over much of this
time period. A long southerly fetch should also allow for seas to
build to near 10 feet across the outer southern coastal waters.
Small Craft Advisories likely for most of the coastal waters.
Thursday...Moderate confidence. Gusty west winds continue. Will
likely need to continue Small Craft Advisories for some of the
waters.
&&
.CLIMATE...
Record Lowest Max Temperatures for Sat March 4...
BOS...21/1896...tied record, previous record set in 1896
PVD...23/1943
BDL...23/1943
ORH...18/2017...new record, previous record 19 degrees in 1943
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Wind Chill Advisory until 7 AM EST Sunday for CTZ002>004.
MA...Wind Chill Advisory until 7 AM EST Sunday for MAZ002>005-
008>012-026.
RI...Wind Chill Advisory until 7 AM EST Sunday for RIZ001.
MARINE...Freezing Spray Advisory until 7 AM EST Sunday for ANZ231>235-
237-250-251-254>256.
Gale Warning until 1 AM EST Sunday for ANZ230>235-237-251.
Small Craft Advisory until noon EST Sunday for ANZ236.
Gale Warning until 7 AM EST Sunday for ANZ250-254.
Gale Warning until 4 AM EST Sunday for ANZ255-256.
&&
$$
SYNOPSIS...Belk/Thompson
NEAR TERM...Doody/Thompson
SHORT TERM...Thompson
LONG TERM...Belk
AVIATION...Belk/Thompson
MARINE...Belk/Thompson
CLIMATE...
Area Forecast Discussion...Updated
National Weather Service Billings MT
741 PM MST Sat Mar 4 2017
.UPDATE...
Weak wave was shooting across central zones this evening and
producing scattered light showers northeast of Billings.
Introduced low PoPs for these locations tonight. Activity should
drift northeast out of the area by midnight, but lingered a low
PoP for northern Rosebud county to account for slightly slower
movement. HRRR no help with this activity, but the GFS did hint
at it, so followed it. Adjusted winds a touch at Livingston as
winds were still gusting to 45 mph there. Winds will be on the
decline tonight and this handled well in current forecast. No
other changes. TWH
&&
.SHORT TERM...valid for Sun and Mon...
Mainly dry weather can be expected into Sunday with best precip
chances confined to the Beartooth/Absaroka and Crazy mountains
and adjacent foothills as southwest flow aloft sets up over the
region. A few inches of snow are possible on southwest to west
faces of the Beartooth/Absaroka mountains. An isolated shower or
two is possible across the plains generally west of Billings.
Gusty winds will continue along the western foothills, but should
be lighter than the past couple of days.
Models remain in overall agreement in an upper low and trough
moving into the Pac NW and moving through the central and northern
Rockies Sunday into Sunday night. Showers are progged to form
along a cold front moving through the area Sunday afternoon and
evening with a transition to snow showers overnight into Monday.
At this time, it looks to be a quick shot with only minor
accumulations. Far eastern areas toward the Dakota border will
have the best chance at some accumulating snow as a surface low
gets organized across the central plains. A couple inches are
possible across the east with higher totals over the Bighorn
Mountains. Gusty northwest winds will accompany the frontal
passage and snow showers, reducing visibilities. Subsequent shifts
will need to monitor for potential winter highlites.
High temperatures are expected to be near 50 west to the lower 60s
in the east on Sunday. Much cooler temperatures are expected for
Monday behind the frontal passage with 30s to 40s for most
locations. STP
.LONG TERM...valid for Tue...Wed...Thu...Fri...Sat...
Heights build Tuesday through Thursday as a quasi-zonal pattern
sets up over the Northern Rockies. This will bring a warming
trend with generally dry weather to the plains as downslope flow
dominates. Shower chances will continue over the mountains with
moisture and energy streaming in overhead from time to time.
Breezy conditions should develop during the midday and afternoon
hours for most areas Tuesday- Thursday as 700 mb height gradient
tightens up a bit and mixing brings down the wind to the surface.
Strong gap winds are possible at times Wednesday and Thursday.
Models continue to prog a frontal system dropping in from the
north Friday and into the weekend bringing the potential for
cooler temperatures and snow.
High temperatures should be in the 30s and 40s early in the work
week...then climb to the 50s for Wednesday-Friday. Central areas
could warm into the 60s on Thursday, with a cooling trend expected
Friday and into the weekend. RMS/STP
&&
.AVIATION...
Winds will decrease this evening but still gust to 35kt at KLVM.
Clouds will increase overnight with showers developing over the
mountains and moving into the adjacent plains after midnight
impacting KLVM and locations northeast of KBIL. VFR conditions
expected with some mountain obscurations late. borsum/TWH
&&
.PRELIMINARY POINT TEMP/POPS...
Sun Mon Tue Wed Thu Fri Sat
-----------------------------------------------------------
BIL 038/058 030/042 026/044 031/058 039/063 037/050 028/043
12/W 32/W 11/N 11/B 11/E 23/W 33/W
LVM 035/047 020/032 019/037 030/053 038/055 036/049 025/037
24/W 42/J 32/J 22/W 10/N 23/W 33/J
HDN 031/061 028/043 024/044 025/060 033/063 032/051 026/045
12/W 53/W 11/N 11/B 11/B 13/W 33/W
MLS 033/062 031/041 025/040 024/051 032/058 034/047 028/043
21/B 75/W 10/N 11/E 21/E 23/W 33/W
4BQ 032/064 029/041 023/040 023/057 031/063 034/052 027/045
00/B 76/W 10/N 01/B 11/B 13/W 43/W
BHK 032/064 029/036 022/035 018/046 029/056 030/044 024/039
00/U 47/J 10/N 01/E 11/B 23/W 33/J
SHR 031/059 027/037 020/039 022/057 032/062 034/053 027/042
01/B 65/W 11/N 11/B 11/B 13/W 33/J
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Duluth MN
531 PM CST Sat Mar 4 2017
.SHORT TERM...(This evening through Sunday)
Issued at 310 PM CST Sat Mar 4 2017
As a long wave trough enters the U.S. via the Pacific Northwest,
surface low pressure was developing in the lee of the Rockies this
afternoon. In response, strong southerly flow has developed and
will increase tonight and produce strong warm air advection.
Yesterday morning when there were low temperatures well below zero
in the northland, the 8h temperatures were around -10C. By
tomorrow morning 8h temperatures are forecast to be in the signal
digits above zero, and rise even more during the day. This big
return of warm air will be brought into our region and a strong 50
kt low level jet. This jet will also bring an increase in
moisture, but the models, especially the NAM, seems to be bringing
in moisture a bit too quickly, considering that surface dewpoints
were still in the 20s at mid afternoon. But by later tonight we
should see a layer of stratus develop over the northland as the
winds decouple and an inversion ensues. This is caught well in the
condensation pressure deficit prog of the local HRRR model. The
challenge for tomorrow is forecasting the dissipation of the
stratus deck as the clouds will make or break the high temperature
forecast. With the higher March sun angle and resulting mixing,
expect the inversion to relax and give us some sunshine. If this
happens later in the day temperatures will not recover and reach
the forecast highs, so this is something to keep an eye on.
.LONG TERM...(Sunday night through Saturday)
Issued at 310 PM CST Sat Mar 4 2017
The operational deterministic models and various ensembles
continue to be in decent spatial and temporal agreement on the
strong upper level trough and surface low that will affect much of
the Upper Midwest Monday/Tuesday. The surface low is expected to
track to the west of the DLH CWA, across North Dakota, and to near
the Manitoba/Ontario border region Monday night. This will result
in the warm sector making a strong push northward, along with
associated strong wind fields and warm/moist advection. This will
result in a good chance of rain and a few embedded thunderstorms
beginning late Sunday night and continuing through Monday. The
best chance of thunderstorms appears to be across eastern
Minnesota and much of northwest Wisconsin Monday afternoon and
Monday evening along and ahead of the strong eastward surge on the
cold front. As is typical this time of year with cold temps aloft,
a few of the stronger updrafts could briefly produce some small
hail and perhaps some gusty winds, but the risk of any severe
storms appears exceptionally low this far north. Enough low level
instability and moisture wraps around to produce some showers
across mainly the northern CWA Monday night and Tuesday, with a
fairly steep gradient from north to south due to moisture
availability. Rain should also rapidly change to snow as much
colder air wraps around the south side of the closing off mid
level low and interacts with the TROWAL region, and this could
result in a few inches of new snow Monday night/Tuesday across the
northern CWA.
Ridging builds in for Wednesday, and is expected to result in the
coldest day of the week. We have lowered the min temps a tad from
guidance during the mid week period, especially across the north.
Thereafter, confidence is much lower as the various model
solutions diverge beyond mid week, and we have stayed very close
to the consensus guidance for now during this time period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 531 PM CST Sat Mar 4 2017
VFR at the start of the forecast with strong warm advection
underway and plenty of cirrus comes with it. All model forecast
soundings are pointing toward MVFR ceilings developing between
03Z and 06Z at all terminals, with patchy IFR. With plenty of dry
air in the low levels, confidence on this occurring is low. Best
spot to see MVFR ceilings is HYR where some of these ceilings are
just off to the southeast. Mention of LLWS still looks good for
tonight. Ceilings should improve to VFR by mid afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 28 49 40 51 / 10 10 30 60
INL 30 52 37 51 / 10 0 20 60
BRD 32 57 44 58 / 0 0 20 50
HYR 31 55 45 57 / 0 10 40 60
ASX 29 55 41 57 / 0 10 40 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
SHORT TERM...CLC
LONG TERM...Miller
AVIATION...GSF
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
853 PM CST Sat Mar 4 2017
.UPDATE...
Mostly light shower activity across the eastern two-thirds of the
area as of this writing. Best chances for rain for the rest of this
evening into Sunday morning are expected east of I-35 and coastal
plains. An upper level trough currently over west Texas is forecast
to push across the area late this evening into Sunday morning and
interact with plenty moisture pushing to the north out of the Gulf.
Drying conditions are expected from west to east as the upper level
trough moves east of the area Sunday. Adjusted weather grids for
Sunday to show an early drying trend than previous forecast. Updated
zones product and sent several minutes ago a PNS with the past 12
hours rainfall reports.
&&
.PREV DISCUSSION... /ISSUED 550 PM CST Sat Mar 4 2017/
AVIATION.../00Z Update/
Upper level trof and associated precipitation continues to move east
across the area. The back edge of the light to moderate rainfall is
currently along I-35 and continuing to shift east. Areas of light
to moderate rain are possible along with drizzle and fog into the
overnight hours through early Sunday morning. Currently all
locations are reporting IFR conditions and these are likely to remain
in place overnight. Could see periods of MVFR cigs, but greater part
of the night IFR will prevail. Will see slow improvement to MVFR
after 17z Sunday then to VFR after 20z. At the 30 hour TAF sites will
see a return of the MVFR cigs around 03z. Winds will be easterly at
5-10 knots tonight then becoming S/SE at 7-12 knots.
PREV DISCUSSION... /ISSUED 250 PM CST Sat Mar 4 2017/
SHORT TERM (Tonight through Sunday Night)...
Throughout the day thus far...rainfall rates associated with the
widespread shower activity has remained light to moderate.
Instantaneous rainfall rates have peaked at about a half inch per
hour thus far this afternoon. VAD wind profile at KDRT indicates a
southwest wind flow at 8kft and according to RAP forecast soundings,
should feed drier mid level air into the western CWA and continue
dissipating the rain shield from the Rio Grande eastward.
TTU-WRF/HRRR/NMM/ARW all agree that the rain shield should continue
to lessen in coverage out west and while upper level support from the
passing shortwave pushes east, will shift the rain area east of the
I-35 corridor around 00Z. As a result, have stepped down the PoP
chances overnight out west and focused the higher PoPs to the east.
Most rain should be completed in the CWA by 18Z tomorrow other than
areas in the extreme eastern zones.
Additional rainfall amounts between now and 12Z tomorrow morning will
be around 1-2 inches south of the I-10 corridor and east of the I-35
corridor with areas north and west will see generally less than an
inch.
LONG TERM (Monday through Saturday)...
A rich moisture environment will continue for the region over the
next several days and allow for slight chance PoPs through Monday. A
cold front passage on Tuesday will up rain chances from the northern
and eastern zones again before clearing overnight and cooling
temperatures back into the low 70s Wednesday and Thursday.
A quick warm up is expected come Friday and into the weekend and
model guidance is advertising low to mid 80s for KAUS by Saturday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 57 70 62 80 65 / 90 40 10 10 20
Austin Bergstrom Intl Airport 57 70 62 80 66 / 100 40 10 10 20
New Braunfels Muni Airport 57 71 61 80 65 / 90 30 10 10 20
Burnet Muni Airport 55 66 60 77 61 / 90 20 10 10 20
Del Rio Intl Airport 56 74 58 81 60 / 30 - - 10 10
Georgetown Muni Airport 56 67 61 78 64 / 90 40 10 10 20
Hondo Muni Airport 57 72 60 80 64 / 80 10 10 10 20
San Marcos Muni Airport 58 70 62 80 66 / 100 30 10 10 20
La Grange - Fayette Regional 59 70 64 81 67 / 100 50 10 10 20
San Antonio Intl Airport 57 71 62 80 65 / 90 20 10 10 20
Stinson Muni Airport 59 73 62 80 66 / 90 20 10 10 20
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...10
Synoptic/Grids...17
Public Service/Data Collection...Williams
Area Forecast Discussion
National Weather Service Hastings NE
702 PM CST Sat Mar 4 2017
.UPDATE...
Issued at 700 PM CST Sat Mar 4 2017
With winds decreasing and relative humidity levels improving this
evening, went ahead and allowed the red flag warning to expire as
scheduled. Otherwise, the fire weather watch for both tomorrow
and Monday remains in tact. No additional changes necessary to
previous forecast at this time.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 445 PM CST Sat Mar 4 2017
Apologize for the delay and briefer-than-usual product today, but
for our coverage area (CWA) the fire weather situation for these
next 4-5 days (including this afternoon) may be the most serious
stretch of fire weather/danger this forecaster has seen in the
past 5+ years, and considerable time was spent trying to pin down
wind/relative humidity (RH) details, coordinate Red Flag
Warnings/Fire Weather Watches etc. It is not very unusual for our
CWA to see perhaps two (maybe rarely 3) consecutive days of fire
weather headlines, but the potential exists here (counting today)
for at least 4 days in a row, with the overall-most serious combo
of strong winds/low RH looking to be Monday and Tuesday. From this
point forward, will defer all discussion of fire weather issues to
the separate Fire Weather section below.
Glossing over the current/recent weather scene: High temperatures
have slightly exceeded expectations this afternoon with most
areas reaching the 70s, despite a bit more high cloud cover than
anticipated especially over northern zones. In the mid- upper
levels, broad low amplitude ridging prevails. A decent lee trough
and deep mixing is driving the south winds with widespread gusts
over 30 MPH in all but the far northern/western CWA.
Now briefly mentioning forecast expectations through these next 24
hours...
This evening/tonight:
Winds die down to more so 10-15 MPH around sunset, but will pick
up again somewhat later this evening as some low level jet induced
mixing kicks in. With slowly-increasing low level moisture, there
could be an area of low stratus that perhaps invades parts of the
eastern CWA, but most of these should slide just off to our east.
Even if the low stratus misses us, some patchy fog cannot be ruled
out especially in central areas as winds lighten again toward
sunrise. Low temps range from near-30 far west/northwest to upper
40s far east/southeast, a decent gradient.
Sunday daytime:
Expect at least mostly cloudy skies unless any low stratus in the
east hangs around for part of the morning before mixing eastward
out of the area. In many ways, similar to today but not quite as
windy overall and with higher dewpoint/humidity levels especially
near/east of Highway 281. High temps aimed into at least low 70s
all areas, and upper 70s far southwest.
Sunday night:
This will be a windy night out of the south(by overnight
standards) as a strong low pressure system approaches. The NAM
models suggests some spotty drizzle in our east, but have left
this out for now as confidence is low. Extremely mild low temps
aimed into the mid-40s to low-50s range most areas.
.LONG TERM...(Monday daytime through Saturday)
Issued at 445 PM CST Sat Mar 4 2017
General overview:
Not surprisingly given all the Fire Weather talk, the vast
majority of the forecast through these 6 days is dry/void of
precip chances and continues a prolonged stretch of above normal
temperatures. By Day 7 (next Saturday), however, there are now
some small precip chances (PoPs) mainly for rain showers in the
forecast, although a few wet snowflakes may not be out of the
question in the overnight/early morning. Also, there is some
uncertainty in temps by next Saturday, as although the official
forecast calls for highs in the 50s/60s, at least one model
(ECMWF) suggests we could be cooler in the 40s. Many details to
work out here.
Briefly covering some daily details...
Monday:
A potentially serious fire weather situation with strong west-
northwest winds and RH 10-20 percent, even despite what could be
slowly falling afternoon temps behind a strong cold front/dryline.
have continued to keep any shower/thunderstorm chances out of our
CWA, but it could be a close call with some models firing them up
within only 50-100 miles east of our eastern border.
Tuesday:
Cooler and not quite as windy as Monday, but still a bad fire
weather setup despite highs only in the 50s.
Wednesday-Thursday:
Broad ridging looks to prevail with southerly breezes and temps
rebounding back into the 60s Wednesday and 70s Thursday.
Friday-Saturday:
Kept the Friday daytime forecast dry, but various low chances
for rain showers enter the picture for parts of the CWA Friday
night into Saturday, and perhaps a few wet snowflakes at
night/during morning as the next low pressure system arrives. As
mentioned above, plenty of uncertainty in Saturday`s temps, which
may not be as warm as we`re currently advertising.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday evening)
Issued at 540 PM CST Sat Mar 4 2017
Gusty southerly winds are expected to diminish some over the next
few hours...and as they do...expect LLWS to increase by mid to
late evening. Expect southerly winds to remain strong aloft...with
model soundings indicating around 50KTS between 1500-2000FT AGL.
This wind shear should diminish by early Sunday morning when focus
shifts to stratus and the potential for some fog at the terminals.
HRRR is indicating dense fog could develop by 12Z, but at this
time...opted to only include MVFR VSBYs for several hours during
the early morning. By mid morning, winds will once again increase
and become gusty out of the south with gusts to 25 KTS possible
at both terminals.
&&
.FIRE WEATHER...
Issued at 445 PM CST Sat Mar 4 2017
As mentioned in the opening paragraph above, at least in terms of
prolonged, multi-day fire weather threats, these four days
(including today) are a pretty serious fire weather threat for our
CWA. Briefly covering each day`s situation:
Late this afternoon:
A Red Flag Warning remains in effect for a few more hours for
roughly 2/3 of the CWA, especially those areas south of a line
from Miller-York (including KS counties). As expected in
in an "update" discussion earlier today, a critical combo of
RH/wind speeds did in fact jump several counties north of original
expectations from preceding shift. At least briefly critical
conditions are likely affecting counties outside the ongoing
warning, but in general most of these other counties should fall
slightly short of meeting the 3+ hour aspect of Warning criteria.
Sunday:
Fortunately for much of the CWA, especially the eastern half,
increased dewpoints/RH should keep serious fire weather issues at
bay. However, much of the western half is expected to see at least
"near-critical" parameters, with our far southwest
(Furnas/Harlan/Rooks/Phillips) most favored to at least marginally
breach critical levels. As a result, these 4 counties have been
assigned a Fire Weather Watch.
Monday-Tuesday:
Both of these afternoons are looking fairly serious for fire
weather/danger within the CWA, thanks in large part to stronger
west-northwest winds which especially on Monday could feature
sustained speeds of 30+ MPH and gusts to around 45 MPH. As a
result, a CWA-wide Fire Weather Watch is already out for Monday.
In all reality, Tuesday afternoon could probably justify a Watch
already as well, but with this still being 72 hours away and so
much else going on headline-wise before then, opted to hold off on
any Tuesday fire weather headlines for now.
Wednesday:
At least for now, fire conditions on this day do not look nearly
as "bad" as the preceding two days, but at least a "near-critical"
combo of wind/RH is possible.
Closing with a quick review of our local fire weather thresholds:
"Critical" means the 3+ hour overlap of relative humidity (RH) of 20-
percent-or-lower and sustained winds/gusts of 20+MPH/25+MPH (in the
presence of sufficiently-dry vegetation/fuels). "Near-critical"
means the overlap of 25-percent-or-lower RH and sustained
winds/gusts of 15+MPH/20+MPH.
&&
.CLIMATE...
Issued at 445 PM CST Sat Mar 4 2017
Although currently/officially expected to fall just short, it
could be a close call with record highs on Sunday afternoon at our
two primary climate sites. The details are as follows...
Record high temperatures for March 5th (Sunday)...
Grand Island: 78 degrees, set in 1978
Hastings: 75 degrees, set in 2009, 1950 & 1910
The current forecast high temperature for both Grand Island and
Hastings is 72 degrees.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...Fire Weather Watch from Monday afternoon through Monday evening
for NEZ039>041-046>049-060>064-072>077-082>087.
Fire Weather Watch Sunday afternoon for NEZ082-083.
KS...Fire Weather Watch from Monday afternoon through Monday evening
for KSZ005>007-017>019.
Fire Weather Watch Sunday afternoon for KSZ005-017.
&&
$$
UPDATE...Rossi
SHORT TERM...Pfannkuch
LONG TERM...Pfannkuch
AVIATION...Rossi
FIRE WEATHER...Pfannkuch
CLIMATE...Pfannkuch
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
919 PM CST Sat Mar 4 2017
.UPDATE...
Issued at 918 PM CST Sat Mar 4 2017
Warm front was located from central Iowa into central Illinois at
mid evening with southerly winds staying up over the area caused
by a tight pressure gradient. Current temperatures are running
above normal highs for this date, and have only made minor
adjustments to going forecast lows. GOES-16 imagery is showing
low clouds moving northward in several channels into eastern
Kansas and western Missouri. The RAP and HRRR show these low
clouds moving into central and northeast Missouri later tonight.
Britt
&&
.SHORT TERM... (Through Late Sunday Afternoon)
Issued at 404 PM CST Sat Mar 4 2017
Quiet weather is expected tonight after gusty southwest to west
winds diminish after sunset. Overnight lows should be 10-15 degrees
warmer than last night. Another unusually warm March day is expected
on Sunday, but increasing cloud cover may keep highs slightly cooler
than they were on Saturday.
42
.LONG TERM... (Sunday Night through Next Saturday)
Issued at 404 PM CST Sat Mar 4 2017
Not a lot of changes to the prev forecast overall.
Trended aoa the warmer guidance for Sun night thru Mon ahead of the
cdfnt. Raised PoPs Mon night with somewhat better agreement in
timing of precip. Not much has changed with this system. Limited
moisture return will limit amount of CAPE across the area. The cdfnt,
and associated precip, will push thru the area Mon night and perhaps
linger into Tues morning after sunrise. However, even the slowest
NAM soln suggests precip exiting our ern/sern counties by 12z Tues.
Sfc ridge will build into the area behind the fnt bringing a brief
cool down, tho still fairly warm max temps for this time of year.
The next wrmfnt will lift nwd thru the area on Thurs.
The next upper trof will approach the region late next week into the
weekend. Have capped PoPs at high chance range for now with
differences among guidance. Do not have a lot of confidence in the
GFS soln for the s/w and associated sfc low as it seems
overdeveloped.
Tilly
&&
.AVIATION... (For the 00z TAFs through 00z Sunday Evening)
Issued at 548 PM CST Sat Mar 4 2017
Dry and VFR conditions are expected at the terminals through the
period. Winds will be out of the south and will gust into the
20-26kt range during the day on Sunday.
SPECIFICS FOR KSTL: Dry and VFR conditions are expected through
the period. Winds will be out of the south and will gust to around
22kts during the day on Sunday.
Britt
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
550 PM CST Sat Mar 4 2017
.SHORT TERM...(This evening through Sunday)
Issued at 300 PM CST Sat Mar 4 2017
A fairly quiet day today with mostly clear skies across the region.
Southeast winds continue to be brisk as we remain between a strong
high over the northern Great Lakes, and a trough of low pressure
across Montana. The short term period looks dry locally, but the
tough part of this forecast is the cloud cover for tomorrow. The
GFS/NAM are just some of the guidance that wants to saturate the
lower atmosphere very quickly. This response makes sense as winds
turn more southerly tonight and surface dew points rise into the
30s. This also means overnight lows will likely be above freezing
for much of southern MN and west central WI.
The stratus building across Oklahoma this afternoon is expected to
advance northward through the night. There are questions though of
how far west that cloud cover will extend by the time it reaches the
Upper Midwest. My concern is the models over-emphasizing the dew
point surge on the cloud cover as 925mb moisture explodes across
this region this evening. I find the HRRR/ECMWF more trustworthy in
this case with sky for tomorrow morning and through the day, which
keeps much of western MN under partly cloudy skies. Expect stratus
east of there, which will make for a big difference in daytime highs
tomorrow. Highest confidence in cloud cover is from Albert Lea
through Eau Claire. Expect highs to reach the 60s in western MN,
while western WI remains about 10 degrees cooler given the current
snowpack and cloud cover tomorrow. Southerly winds of 10-15 MPH
with gusts to 20 MPH are expected.
.LONG TERM...(Sunday night through Saturday)
Issued at 300 PM CST Sat Mar 4 2017
Things get busier quickly as we head into the longer term, then
the guidance quickly becomes clueless in terms of forecast
confidence toward the end of the longer term. There is reasonable
agreement with the main system of concern, which is a strong surface
low which will take shape over the High Plains Sunday evening then
quickly intensify as it moves northeast to near the Minnesota/Canada
border by Monday evening. There are some minor differences in the
position of the surface low and timing of the cold front across our
area, but things are in much better agreement than a day or two ago.
The ECMWF is by far the slowest of the deterministic solutions with
the front, so its forecast is washed out to some degree by blending
guidance from the GFS, Canadian, and NAM. Will bring some PoPs into
the area overnight Sunday night then shift them eastward through the
day on Monday into Monday night. The best chance for precipitation
still looks to be over the eastern portion of the forecast area, as
it gets the greatest moisture return before the arrival of the
forcing associated with the cold front and upper short wave. Thunder
still looks to be a possibility over the central and eastern portion
of the area Monday into Monday evening, and included that
possibility across an area fairly consistent with what is shown by
the SREF probability of thunder guidance. It`s a bit too early to
say if there is much potential for severe weather, but cannot rule
it out given the forecast wind fields, even if instability is
marginal. Large scale strong winds will arrive behind the front, and
look to increase further on Tuesday and continued cold advection
helps to further destabilize low-level lapse rates and allow for
strong winds aloft to mix to the surface. Continued to mention
sustained winds above 30 mph across the typically windier locations
on Tuesday, with gusts near 50. Some of the guidance suggests even
greater wind potential, so will try to refine things as we get
closer in time.
After the Monday system, confidence in the forecast specifics wane
as the week progresses given the disparity of solutions from the
deterministic guidance and the absurd amount of spread in the
ensemble solutions. Included a chance for some light precipitation
Wednesday afternoon/evening across the north and east as we see a
week short wave trough embedded in northwest flow move through the
area. Another shot as some precipitation looks to move through later
Thursday into Friday as a weak surface low track from the northern
Rockies toward the Great Lakes. However, by this point the guidance
is quite a bit different in position and timing of things, with the
ECMWF quite a bit farther south in comparison to most other
guidance. As a result, the ECMWF still drags more cold air south
into our area by Saturday as it begins to develop another surface
low over the southern Plains. However, it should be noted that the
ECMWF isn`t as bullish with the cold air as in previous runs. Wind
up mentioning some chance PoPs for Saturday, but if the baroclinic
zone is shunted as far south as the ECMWF indicates then it may wind
up cool and dry.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 550 PM CST Sat Mar 4 2017
Stratus over WI is expected to continue riding southeast low level
winds to the northwest toward the arrowhead. Only location that
may get into it is EAU. Even if EAU sees MVFR cigs, expect them
to clear out by 6z as they continue to head toward Duluth. After
that, we wait on where stratus currently coming out of Oklahoma
ends up tomorrow. AXN is the only terminal that we have high
confidence in saying they will not see MVFR stratus Sunday, with
MVFR chances increasing as you go east, with it almost looking
certain by Sunday morning in EAU. Followed a GFSlamp depiction for
these cigs for now, with them coming up across RST/EAU, but
remaining east of the rest of the terminals. Cigs really do not
look to tank everywhere else until Sunday evening when 50 degree
dewpoints begin nosing into southern MN.
Wind shear continues to look like a strong bet, with both strong
speed and directional shear as 2k ft winds out of the south
between 40 and 50 kts lay over the top of our southeast surface
winds that will be sustained around 15 kts. Wind shear signal
looks greatest between 8z and 14z.
KMSP...Have continued to take a more optimistic track for cigs
this period, holding off on MVFR cigs until Sunday evening as low
levels of both the GFS and NAM look overly moist. With that said,
the HRRR currently ends with low stratus slamming into MSP at
15z, so this is a lower confidence optimistic forecast, but will
wait until we can get a better handle on how stratus currently
over Oklahoma tracks toward this direction tonight before getting
too aggressive with cigs.
/OUTLOOK FOR KMSP/
Mon...MVFR ceilings possible. Chc shra/tsra. Winds S 15G25kts
bcmng SW 20G30kt.
Tue...VFR and Windy. Winds W 30G40kts.
Wed...VFR. Wins WNW 10kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&
$$
SHORT TERM...SPD
LONG TERM...
AVIATION...MPG
Area Forecast Discussion
National Weather Service Spokane WA
345 PM PST Sat Mar 4 2017
.SYNOPSIS...
The weather will remain active this weekend, as a cold upper level
trough begins to shift into the region. Look for snow showers
primarily over southeast Washington and the central Idaho
Panhandle through this evening. The threat of snow will spread
across the remainder of the Inland Northwest tonight and on
Sunday. More snow will be possible on Tuesday before turning wet
and mild around mid week. Temperatures will warm above average
Wednesday and Thursday.
&&
.DISCUSSION...
Tonight and Sunday...A complex weather situation tonight as a
large low pressure system off the Washington coast sends a strong
short wave into the region. Ahead of this wave...a mid level and
surface boundary lingers over SE Washington into the Central
Panhandle Mountains.
Through this evening...attention will be on the convection that
continues along this boundary. Snow rates up to 2 inches per hour
have been observed under the heavy showers as low as 1500 feet.
These rates are fast enough to stick on roadways and thus a winter
weather advisory remains in place. The past several HRRR runs
show these snow rates persisting through the evening in localized
bands. Will be expanding this advisory to include the Lewiston
area and Camas Prairie above 2000 feet where heavy snow showers
have been observed on area cams this afternoon. Under heavy
showers snow can be expected at all elevations.
The next wave moves in overnight and models solutions vary
greatly with qpf. The reason is the depth...and track of a surface
low that develops over Oregon. As of 1 pm this low had already
developed over North Central Oregon and was about 2-3mb deeper
than all guidance. With a deeper low forecast leans in the
direction of the GFS but with a slightly stronger solution. With
the low tracking towards Moses Lake overnight easterly upslope
flow and isentropic ascent into the Cascades...Wenatchee
area...Waterville Plateau will produce light to moderate snow
totals. The low then tracks up into the Okanogan Valley and
Highlands Sunday morning with a band of wrap- around snow on the
back side of the low. Will be adding these areas to the winter
weather advisory beginning overnight tonight. Slight variations in
the low track will impact snow totals so confidence is precise
amounts is low. Elsewhere a quick shot of snow is expected with
about an inch of snow accumulation...except 1-3 inches of
additional snow for the Camas Prairie and Central Panhandle
Mountains with added upslope flow.
Once this low exits showers linger into Sunday afternoon due to
steep lapse rates that result from daytime heating and a very cold
atmosphere with 500mb temps down to -38C. Soundings continue to
support snow or graupel out of these showers. JW
Sunday night through Monday Night: The Inland Northwest will be
under a cold and unstable upper level trough of lower pressure.
Mid level lapse rates will be very unstable Sunday night and
Monday at around 8.5 C/km in the 700-500 mb layer. Models show the
center of the upper level low pushing across Sunday night. The
associated vorticity maximum will produce some lift and looks to
track mainly across southeast WA and into the Central Panhandle
Mtns. Southwesterly flow will also result in favorable orographics
across the Northeast Mtns and in the ID Panhandle. The vorticity
maximum that tracks across will be weak with orographics likely
playing a more dominant role. With how unstable the atmosphere
will be, it will not take much mechanical lift to get air parcels
to lift freely up in the atmosphere. A strong convective component
will open the door for bursts of heavy snow showers and potentially
some lightning for the afternoon on Monday. Lifted condensation
levels will be cold in this air mass, so it will be tough to get
much charge separation but a few lightning strikes is not out of
the question. Expect the potential for 2 to 4 inches of snow in
the Panhandle valleys. Moderate snow accumulations over Lookout
and Stevens Pass with winter travel conditions will be possible as
well .
...LIGHT VALLEY SNOW AND MODERATE TO HEAVY MOUNTAIN SNOW ON
TUESDAY...
A strong warm front will move up across the region on Tuesday. All
areas will start out with snow in the morning. Temperatures at 850
mbs will be between 6-7 Celsius below zero at onset of the
precip. This colder air will take some time to warm up through the
day with snow expected in the valleys across much of the mountain
areas and the northern and eastern basin (including the Spokane
Area and eastern portions of the Palouse). Surface temperatures
should see some warming though now that we are in March. This
will result in heavy wet snow, especially during the afternoon
hours. Most valley locations that will see snow is expected to
accumulate around 1 to 3 inches with local accumulations of around
4 inches in the northern mountain valleys. I lowered high
temperatures a bit from what we had previously since we will see
precip through the afternoon. Conversely, I also warmed the
overnight low temperatures a bit for Tuesday night, since we will
continue to see WAA into the region as another surface low
develops southwest of Vancouver Island. Snow levels will continue
to rise through the night with snow changing over to rain across
the basin by the late afternoon/evening. Heavy snow will possible
over the mountains. A 12-18 inches will be possible over the
higher terrain of the east slopes of the northern Cascades and
5-10 inches possible over the higher terrain of the Okanogan
Highlands to the ID Panhandle. /SVH
Wednesday through Saturday...
A continuous, steady stream of moisture flowing off the Pacific
Wednesday into Thursday will bring widespread valley rain and
high mountain snow. Light to moderate rain and much warmer
temperatures will likely cause another meltdown of mid and low
elevation snow which in the recent past has caused the following
impacts:
*Rising creeks and streams although no mainstem rivers are
expected to flood.
*Local ponding of water in areas that still have snow to melt and
urban areas with clogged storm drains.
*Windy conditions in the mountains and Breezy conditions across
the Central Basin and Palouse
Longer range models have been in pretty good agreement that
anywhere from .5 to 1.0 inch of precipitation could fall in
extreme eastern WA and the Idaho Panhandle Wednesday into early
Friday morning. Higher amounts of precipitation are likely in the
mountains with snow levels rising above 5000 feet in most areas
Thursday.
Models do start to diverge by Friday with how quickly the cold
front will push through. The GFS being the most aggressive would
shunt preciptiation to the south and cool off the region
significantly by Friday. The ECMWF is less progressive allowing
another wave to move out of the northwest potentially prolonging
precipitation into the early weekend period.
Regardless, confidence is increasing that a significant
and prolonged mid to low elevation rain event will occur centering
around the middle to late next week. Everyone should prepare
their areas if local flooding has been an issue in similar melting
scenarios from recent past. TC
&&
.AVIATION...
00Z TAFS: A stalled frontal boundary over SE Washington into the
south Idaho Panhandle will produce numerous showers falling as a
mix of rain and snow in Pullman and Lewiston this evening. This
will keep the boundary layer very moist with MVFR conditions
common with occasional IFR conditions at KPUW from 02Z-05Z. Some
model guidance suggest these showers may reach as far north as
Spokane area TAF sites in the evening but consensus gives KCOE the
best chance. Still the moistening boundary layer over the palouse
and low level south-southwest winds may advect enough moisture
for a brief period of IFR/MVFR conditions for KGEG/KSFF this
evening between 06Z-10Z. As this wave tracks north overnight into
Sunday expect a 3-5 hour period of snow and lowering
CIGS/visibilities near KEAT as well. Behind this wave gusty
southwest winds quickly develop for KGEG/KSFF/KMWH into Sunday. TC
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 28 39 24 37 24 37 / 40 80 50 70 40 100
Coeur d`Alene 27 39 24 37 23 37 / 50 80 60 80 70 100
Pullman 28 38 25 38 25 40 / 90 40 70 80 60 100
Lewiston 33 45 28 44 28 46 / 90 40 60 60 40 90
Colville 26 39 23 40 22 37 / 10 80 50 50 20 100
Sandpoint 27 37 24 36 23 35 / 40 90 70 80 70 100
Kellogg 27 35 23 33 22 34 / 90 90 80 90 90 100
Moses Lake 29 45 26 41 25 42 / 60 30 20 20 10 90
Wenatchee 28 42 25 41 24 40 / 70 30 30 30 10 100
Omak 25 42 21 40 21 38 / 50 80 30 20 10 90
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Weather Advisory until noon PST Sunday for Central
Panhandle Mountains-Lewis and Southern Nez Perce Counties-
Lewiston Area.
Winter Weather Advisory until 7 AM PST Sunday for Idaho Palouse.
WA...Winter Weather Advisory until 7 AM PST Sunday for Northeast Blue
Mountains.
Winter Weather Advisory from midnight tonight to noon PST Sunday
for East Slopes Northern Cascades.
Winter Weather Advisory from midnight tonight to 7 AM PST Sunday
for Waterville Plateau-Wenatchee Area.
Winter Weather Advisory from 4 AM to noon PST Sunday for
Okanogan Highlands-Okanogan Valley.
&&
$$
Area Forecast Discussion...UPDATED
National Weather Service Reno NV
741 PM PST Sat Mar 4 2017
.UPDATE...
Convective nature of precipitation was becoming more evident based
on latest satellite and radar imagery with main band developing
from San Francisco to the northern Sacramento Valley this evening
with smaller bands on the west slopes of the Sierra beginning to
move into the Tahoe Basin. Latest HRRR reflects these trends well
and along with the 00Z NAM, suggest snow showers will continue to
intensify from Alpine County northward and occasionally move into
the Sierra Front late this evening and ahead of main band which
will move southeast through the area mostly overnight. Heaviest
and most pronounced snow should reach the Tahoe Basin between
05Z-07Z and then spill over into western NV between midnight and
4am. This front will then hang up over the central Sierra of Mono
County as it awaits a secondary cold front that will finally push
across Sunday morning. With the cold air in place, a secondary
round of snow along the Sierra Front will bring more potential
impacts for the early to mid morning period Sunday. Other than to
delay weather across Mono County this evening, the forecast is on
track. A couple of minor updates will be issued to reflect trends
in Mono County and again later to remove the wind advisory
headline on time for the Sierra Front and northern Washoe County.
Hohmann
&&
.SYNOPSIS...
Winds will remain gusty this weekend as a cold front moves through
the region. Heavy snow is likely for the Sierra tonight and Sunday
with some snow accumulation across western Nevada north of
Highway 50. Snow showers will gradually diminish through Monday
but temperatures will remain below normal. High pressure returns
by mid to late next week for warmer conditions forecast. A return
to a wet pattern is possible next weekend.
&&
.PREVIOUS DISCUSSION... /Issued 220 PM PST Sat Mar 4 2017/
SYNOPSIS...
Gusty winds will continue this evening as a strong cold front
moves into the region. Heavy snow is likely for the Sierra
beginning late this afternoon through Sunday. Snow accumulation
for western Nevada is likely Sunday morning north of Highway 50.
Much colder Sunday with snow showers continuing with less showers
on Monday. High pressure returns by mid to late next week with
warmer and drier conditions forecast. A return to a wet pattern is
possible next weekend.
SHORT TERM...
Overall, the forecast remains on track for the next 24 hours. A
few changes were made, but they are more to indicate the
confidence we have in the next 24 hours.
WINDS: Sierra ridges are gusting to 90 mph with many valley
locations seeing gusts 40 to 55 mph, in line with the forecast.
There are a few higher gusts to 70 mph in wind prone areas and
this will continue through the evening. All wind statements will
continue through expiration. Even Lovelock/Fallon getting into the
act with good mixing and there is dust coming off the Carson Sink.
Added dust to the forecast for this evening there.
The winds will gradually diminish some overnight, but not
completely weaken. They will remain brisk tomorrow with some gusts
30-40 mph which will make for a decent wind chill. We did issue a
Lake Wind Advisory for Pyramid Sunday after the Wind Advisory is
set to expire.
SNOW: Precip is increasing across Northwest CA and will continue
to push east this evening. Everything is on track, and it now
looks as if the main frontal band will occur after the snow levels
will drop to the valley floors along the Sierra Front. The
heaviest bands are still expected from 10 pm tonight through 10 am
Sunday and shift from north to south over that time. The main
change was to issue a winter weather advisory for the Sierra Front
with the higher confidence in snow sticking to the roads,
especially above 5000 feet. Elsewhere, a modest increase in
snowfall was made for the Sierra due to the convective nature of
the snowfall. Large dendrites are likely and snow rates will reach
2 inches per hour in the heavy bands.
After the main front and bands move through, convective snow
showers will continue Sunday with much colder temperatures, a good
20 degrees colder than today. A few more inches are possible in
the Sierra. While lake effect snow would be a good possibility
with 700 mb temps down to -16 C, the 700 mb winds are 40 kts, and
the shear will be too much for anything organized. Snow showers
will gradually wind down from south to north into Tuesday. By
Monday afternoon, most snow showers should be confined north of a
South Lake Tahoe to Lovelock line.
Tuesday, much drier except for a small chance of showers north of
Susanville and Gerlach. Temperatures will also warm up quite a bit
Tuesday as 700 mb temps begin to approach the freezing mark. Winds
will also diminish with just the ridges being gusty at times.
Wallmann
LONG TERM...Wednesday through Saturday...
Model simulations continue to show the storm track retreating north
into the Pacific Northwest midweek, supporting relatively mild
conditions. Expect slightly above average afternoon temperatures (55-
65 lower valleys, 44-55 Sierra valleys) Wednesday and Thursday.
Thursday night and into next weekend, model simulations continue to
differ on the strength of a blocking ridge over the Aleutians as a
trough drops south out of British Columbia. This has implications
both with respect to how much cold air moves south into CA/NV for
Friday into the weekend and also as to how much Pacific moisture
gets entrained into the westerly flow pointed towards the west
coast. Atmospheric river outlook tools show a weak signal for the
weekend but with an increasing signal for the first half of next
week. The upshot is expect a return to active winter weather Friday
and this weekend with snow levels likely below pass levels but
otherwise highly uncertain at this time. JCM
AVIATION...
Strong surface wind gusts 35-50 kts at area terminals will generally
be strongest now through this evening. However for KMMH/KHTH the
strongest gusts are expected just before FROPA between 06-12z
tonight. For KTRK/KTVL expect a decrease in winds after the snow
arrives with gusts 20-25 kts after 03z tonight. For western NV
terminals the strongest gusts should also decrease somewhat after
03z but peak gusts 30-40 kts could continue through at least 12z.
LLWS potential increases again tonight after midnight post-FROPA as
the surface winds may decouple from the strong winds aloft.
Widespread IFR conditions due to snow are likely in the Sierra after
00z this evening through Sunday. A foot of snow accumulation is
likely at KTRK/KTVL during this period. Snow spreads south reaching
Mammoth Lakes around 09z with up to 6 inches possible at KMMH by
Sunday afternoon. As far as western NV terminals including
KRNO/KCXP/KMEV, expect at least an inch or two of snow between 06Z-
12Z (10PM Saturday to 4AM Sunday) Sunday. Between 12Z/4AM and
16Z/8AM Sunday, additional snow showers could bring another couple
inches but this is much more uncertain and depends where the
heaviest snow showers set up. JCM
&&
.REV Watches/Warnings/Advisories...
NV...Winter Storm Warning until 4 PM PST Sunday NVZ002.
Wind Advisory until 10 PM PST this evening NVZ003-005.
Wind Advisory until 4 AM PST Sunday NVZ001-004.
Winter Weather Advisory until noon PST Sunday NVZ003.
Lake Wind Advisory from 6 AM to 6 PM PST Sunday for Pyramid Lake
in NVZ004.
CA...Winter Storm Warning until 4 PM PST Sunday CAZ071-072.
Wind Advisory until 10 PM PST this evening CAZ070.
Winter Storm Warning until 10 PM PST Sunday CAZ073.
&&
$$
For more information from the National Weather Service visit...
http://weather.gov/reno