Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/27/17
Area Forecast Discussion
National Weather Service Denver/Boulder CO
752 PM MDT Thu Oct 26 2017
.UPDATE...
Issued at 732 PM MDT Thu Oct 26 2017
Latest radar shows the bands of snow showers over the Denver
metro area and northward are diminishing at this time. Best chance
of snow over the next hour or so will be south of Denver over the
Palmer Divide so have trended the grids in this way. Other
adjustments to the grids this evening are more cosmetic. Overall
expected lower clouds and lingering showers until 05z then
clearing overnight under increasing subsidence. Gusty northerly
winds over the eastern plains will persist through the evening
then decrease after midnight then pick up again by Friday
afternoon.
&&
.SHORT TERM...(This evening through Friday)
Issued at 219 PM MDT Thu Oct 26 2017
Latest GOES-16 imagery, radar, and mesonet data are showing signs
that this storm really lacks a punch. Radar echoes have been weak
and checking web cams beneath the echoes shows nothing reaching
the ground along and east of I-25. West of I-25 snow is reaching
the ground presently and will continue for a few hours. The near-
surface air behind the cold front is cold but quite dry. Thus
have trimmed PoPs significantly below 6000 feet elevation, as well
as QPF. At this point do not expect any precipitation to reach
the ground east of US85 across the Plains, nor east of the Palmer
Divide. We have also trimmed snow amounts in the foothills given
the latest trends. HRRR model trends have been really good today
hitting the timing and location of the precipitation/virga, and
have sided with this model for afternoon into early evening trends
which have reduced snow amounts everywhere. Now thinking 1-3
inches across the favored east slope foothills where upslope flow
is strongest and no accumulation below 6000 feet elevation.
Flurries and up to a trace are expected across the Palmer Divide.
The short wave trough and associated vertical motion is still
moving quickly south across our area and any precipitation that
develops should exit north to south, from Larimer/Boulder Counties
around 5 PM, metro Denver 6 PM, Palmer Divide 7/8 PM, and
Summit/Park County by 10 PM. No significant travel issues are
expected across our area.
With the departing system, strong subsidence begins in earnest not
long after midnight. The surface ridge will be right over Denver
metro overnight, leading to much weaker winds area-wide and
clearing skies. Will be a cold night area-wide with lows in the
low 20s across the urban heat islands, teens elsewhere.
A strong trough over the northern Plains means Colorado is in NNW
flow aloft. Neutral temperature advection at 700 mb and a lack of
downslope flows means Friday will be crisp, cold, and
precipitation free. Expect highs in the mid 40s Plains and mid
30s to low 40s in the mountains.
.LONG TERM...(Friday night through Thursday)
Issued at 219 PM MDT Thu Oct 26 2017
A northwesterly flow aloft will prevail through the middle of
next week. Weak troughs embedded in the northwest flow will bring
reinforcing shots of cool air along with chances for light
precipitation. This pattern is also expected to bring gusty winds
at times, especially to the eastern plains.
A north-northwest flow aloft will bring cool conditions Friday
night and Saturday. Mid level moisture embedded in the flow is
expected to bring clouds most of the day Saturday. Orographic lift
over the northern mountains may produce a few snow showers over
the mountains. Otherwise, dry conditions are expected.
Ridging will prevail Saturday night and early Sunday. This will
result in mostly clear skies and warmer temperatures for Sunday.
This warmth will be short lived as a cold front backs into the
area Sunday afternoon. If this front speeds up, highs may not
climb as high as expected.
Two troughs will be hitting the area early next week. One early
Monday and the next one Tuesday. Best chance for precipitation
will come Monday with the first system, though there will also be
a chance for precipitation through Tuesday. Expect most if not all
the precipitation to fall as snow. Highs early next week will be
chilly with readings in the upper 30s to lower 40s across
northeast Colorado.
A warming trend begins Wednesday as flow aloft starts to turn
more westerly. An upper level trough moving across the northern
plains may bring gusty winds to northern parts of the area. Dry
conditions should prevail under this pattern.
Weather pattern looks to shift Thursday to a westerly zonal flow.
A ridge is expected to pass over Colorado Thursday in the
westerly flow aloft. This will result in mild and dry conditions.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 732 PM MDT Thu Oct 26 2017
MVFR cigs bkn-ovc 020-030 kft agl this evening then sct clouds
around 050 kft agl overnight. North/northeast winds generally 8-14
kts at KDEN through 06z then decreasing to speeds aob 10 kts
overnight. Wind direction similar at KAPA and KBJC overnight but with
slightly lesser speeds. VFR conditions Friday with no aviation
impacts. Surface winds on Friday will be weak and east/southeasterly
in the morning, then northeasterly around 10 kts by the aftn.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Cooper
SHORT TERM...Schlatter
LONG TERM...Meier
AVIATION...Cooper
Area Forecast Discussion
National Weather Service Medford OR
845 PM PDT Thu Oct 26 2017
.DISCUSSION...Evening update. The stable pattern remains over the
region, and tonight should see a repeat of what we saw last night.
Current forecast looks on track and will not update this evening.
.SHORT TERM...Low clouds are quite persistent in the Umpqua Basin;
otherwise clear sky will prevail into this evening across the rest
of the forecast area. The ridge of high pressure will continue
through the weekend with mild daytime temperatures for inland
areas. The thermal trough continues at the coast but with light
pressure gradient. The surface low pressure is forecast to move
north and then slightly offshore of Coos Bay on Friday. Models
show plenty of low level moisture in the Umpqua Basin so
confidence is moderate to high that we will see another night of
low cloud cover. The HRRR short term model show coastal winds
turning to southerly shortly after midnight but this may be too
early for low clouds to spread past Cape Blanco tonight.
Confidence is higher for Friday night for low clouds becoming more
widespread along the coast.
There is little change in the upper level pattern through
Saturday. On Sunday the long wave ridge shifts slightly west and
allows NW flow to set up. The GFS and to some extend the ECMWF
brings a weak short wave down to northern Oregon. Little change is
expected with this trough except for cooler temperatures.
.LONG TERM (Monday through Thursday)...Monday through Tuesday,
high pressure rebuilds into the coastal waters but with north to
northwest flow aloft. This will keep temperatures down to seasonal
norms for our forecast area. On Wednesday, the GFS is more
aggressive with the next short wave disturbance coming into
Vancouver Island. This is the precursor to the next pattern
change. We`ve introduced rain chance for our area Thursday as
both GFS and ECMWF are quite similar on the position of the long
wave trough offshore around 130W. Confidence is higher that we
will see rain into the Rogue Valley Thursday night into Friday.
/FB
&&
Models indicate offshore flow at the north coast tonight, which may
limit the amount of low conditions there, but with shallow moisture
still in place, expect some IFR/LIFR conditions to form in the
Coquille Valley, which may extend into KOTH. A southerly stratus
surge in the coastal waters south of Cape Blanco may bring some low
ceiling/fog to near Brookings.
Roseburg and the Umpqua valley will see IFR and LIFR conditions
tonight. There is plenty of moisture still in that valley, and the
clear skies should allow fog to form.
-Smith
&&
.MARINE...Updated 215 PM PDT Thursday 26 October 2017...Moderate
north winds will continue through early this evening, but the
thermal trough along the coast will weaken and a weak surface low
will move northward along the coast tonight causing winds to
diminish. Even so, seas are expected remain choppy tonight due to a
fresh north to northwest swell. Light winds are expected Friday into
Saturday. However, a long period, high and steep west swell around
20 seconds is expected to move into the area Friday evening through
Saturday night, bringing conditions hazardous to small craft again.
West swell is expected to peak at 11 to 12 feet at 19 to 20 seconds
Saturday morning into Saturday afternoon. Will allow future shifts
to hoist any additional advisory products associated with this long-
period swell event after current advisories expire. -Spilde
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Beach Hazards Statement from Friday afternoon through Saturday
evening for ORZ021-022.
CA...None.
Pacific Coastal Waters...Beach Hazards Statement from Friday
afternoon through Saturday evening for PZZ350-356. Small
Craft Advisory until 5 PM PDT this afternoon for PZZ350-356-370-
376. Small Craft Advisory for hazardous seas until 5 AM PDT
Friday for PZZ350-356-370-376.
$$
FJB/FJB/MAS
Area Forecast Discussion
National Weather Service Pueblo CO
344 PM MDT Thu Oct 26 2017
.SHORT TERM...(This evening through Friday)
Issued at 344 PM MDT Thu Oct 26 2017
A fast moving upper level disturbance will move from north to south
over the area tonight, spreading colder air into the area. This
system will bring strong northerly winds to the southeast plains
thru the evening with gusts of 40-45 mph, possibly a little higher
in some areas. Precip will spread from north to south, mainly along
the eastern mtns and I-25 corridor area from late this afternoon
into the evening hours. Temps this evening will be cool enough along
the I-25 corridor that there should be some snow or mixed rain and
snow depending on how cold it gets during the time-frame that precip
falls. It still looks like the Palmer Divide could see around an
inch of accumulation, with maybe an inch or two in portions of
Teller county and around 3 inches on Pikes Peak. Upslope flow along
the southern I-25 corridor and southern Sangres could result in 1 to
3 inches at the lower elevations and 3 to 6 inches at the higher
elevations. The central mtns will also see some snow but it
shouldn`t amount to much. The lastest NAM shows breezy easterly
winds developing in the San Luis Valley this evening, with some
light pcpn spilling into the southern portions of the valley thru
about midnight. The HRRR is not showing this pcpn. Will include
just some isold pcpn for the San Luis Valley this evening. Late
this evening, pcpn chances will be decreasing/ending from north to
south, with the southeast foothills, southern Sangres and southern I-
25 corridor seeing pcpn the latest, but it is expected to end by 6
am. Low temps tonight should mostly be in teh lower 20s at the
lower elevations, but there could be some upper teens as well,
especially over northern El Paso county.
The main concern for Fri is the potential for Red Flag conditions
over portions of the southeast plains. Dry weather is in store for
Fri, along with cooler than average temps. Gusty northern winds are
expected acrs the far southeast plains, especially from the late
morning through the late afternoon hours, with gusts around 30 mph
expected. At the same time, afternoon humidities are forecast to
fall to between 10 and 15 percent. The fuels over the far southeast
plains are dry, and that combined with the gusty winds and low
humidities should lead to a 3-4 hour period where Red Flag criteria
will be met over Kiowa, Bent and Prowers counties. Therefore, will
issue a warning for these areas from Noon until 6 pm.
.LONG TERM...(Friday night through next Thursday)
Issued at 344 PM MDT Thu Oct 26 2017
Main longer term issue is the amount of impact that next system
has on forecast district from Monday into Tuesday as well as
temperatures and winds.
Initially, from Friday evening into Sunday night, anticipate
basically dry conditions in combination with near to above
late October seasonal temperatures as generally dry northerly to
northwesterly upper flow prevails over the forecast district.
Please note that next north-northeasterly surface surface moves
across eastern sections Sunday night.
Then, meteorological focus shifts to the Monday into Tuesday
time-frame as healthy upper disturbance(per PV analysis/etc.) and
somewhat favorable moist easterly flow develops over portions of
the forecast district. For sensible weather, will depict cooler
temperatures(below late October seasonal averages) and increased
precipitation chances(favoring higher terrain and southern
locations) during the Monday into Tuesday evening time-frame.
A return to drier and warmer conditions is still anticipated over
the forecast district from Wednesday into next Thursday as upper
ridging returns to southern Colorado.
The highest potential for gusty winds over the forecast district
during the longer term should be experienced from Friday evening
into Saturday evening and then again Tuesday(generally favoring
eastern sections).
Warmest temperatures over the CWA during the longer term should be
noted Sunday and then again by next Wednesday and Thursday, while
coolest temperatures are anticipated Monday and Tuesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 344 PM MDT Thu Oct 26 2017
Strong northerly winds are expected to continue at KCOS and KPUB
into the evening hours. There will be a chance for pcpn at both KCOS
and KPUB this evening, but the chances for pcpn should end by
midnight. KCOS could see enough snow showers this evening to briefly
restrict the vsby and lower cigs into the MVFR category. Otherwise,
from late tonight through Friday, VFR conditions are expected at
KCOS and KPUB.
KALS is expected to see gusty easterly winds develop this evening
and forecast soundings show the ceiling lowering to around three-
thousand ft. There may also be some showers this evening. Could see
ceiling lower into the MVFR category or it could remain low VFR, and
these lower ceilings are expected into Fri morning. VFR conditions
are expected at KALS Fri late morning and afternoon.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 6 PM MDT Friday for COZ234>236.
&&
$$
Area Forecast Discussion
National Weather Service San Diego CA
858 PM PDT Thu Oct 26 2017
.SYNOPSIS...
It will be slightly cooler this weekend, but still above average
as weak offshore flow and high pressure aloft continue. There is a
small chance of patchy coastal fog tonight along with the
possibility of stratus moving onshore mainly the far southern San
Diego County coast. Cooler early next week with more clouds as
the marine layer deepens under weak low pressure aloft. A more
Fall-like weather pattern is possible for the end of next week as
a deeper trough develops along the West Coast.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
...Update...
Aside from smoke from the Wildomar fire and from a fire in Mexico,
the sky was clear this evening. Much cooler as well...a relief
from the recent heat wave! A tranquil night is expected. Did
increase sky coverage over far southern San Diego County along the
coast as some stratus is moving north off Baja. HRRR shows it not
making it to the coast, but it is going to be a close call and
could affect the southwest coast. There is also a low probability
of patchy coastal fog developing. Aside from sky coverage, no
additional forecast changes were made this evening.
...Previous Discussion (Issued at 1239 PM PDT Thu Oct 26 2017)...
Satellite imagery midday showed clear skies across SoCal, even
though some smoke was in the air over San Diego County, limiting
long-range visibility in some areas. Surface pressure gradients
remained offshore around 6 MBS from SW NV to KSAN, but were weaker
than yesterday. Wind reports were mostly light midday and temps
were running between 5 and 15 degrees F lower than yesterday.
High pressure remains anchored aloft along the West Coast today,
despite being weakened by numerous shortwaves dropping south farther
inland over the Great Basin. The southbound shortwaves will
maintain a weak to locally moderate offshore flow at the sfc across
SoCal, strengthening diurnally. The offshore flow and ridge aloft
will continue above average temperatures through Saturday. Some
patchy fog is possible along the immediate coast tonight as the sea
breeze draws in higher sfc dewpoints. Confidence is low for any
development at this time with dewpoints still very low along the
coast and mostly clear conditions well offshore.
For Sunday/Monday, a weak low pressure center aloft will drop SE
over SoCal, reinforcing the onshore flow and building the marine
layer for noticeably cooler weather and slightly below average
daytime temps well inland. The cooler weather will linger into
Tuesday, then it will be a bit warmer again mid next week as weak
ridging returns aloft.
A larger long-wave pattern shift is possible toward the end of next
week for greater cooling, and even perhaps a shot at some precip.
&&
.AVIATION...
270330Z...Coast...P6SM vis and SKC through early tonight. Very low
stratus/dense fog is currently 20 miles south of Imperial Beach, and
heading north. It could potentially impact KSAN and KCRQ by early
Friday morning. Bases of 100-300 ft msl, with tops 500 ft msl and
areas of vis down to 1/4 sm are possible. Best chances for dense fog
occurrence for KCRQ and KSAN is during the 27/1000-1400 UTC time-
frame. Clear Friday afternoon.
Valleys/Mountains/Deserts...Mostly P6SM vis and SKC through Friday.
Areas of smoke near Wildomar.
&&
.MARINE...
Small chance of patchy dense fog tonight, with visibility of 1 mile
or less. Otherwise, no hazardous marine weather is expected through
Tuesday.
&&
.BEACHES...
A steep northwest swell from 295 degrees will enter the Southern
California waters on Saturday, peaking at 5 ft/20 seconds on Sunday
south of San Clemente island. This swell energy will bypass most of
the Southern California beaches, but exposed beaches of southern San
Diego County will see elevated surf of 3-6 feet and strong rip
currents Sunday and possibly into Monday before the swell lowers.
&&
.FIRE WEATHER...
Warm and dry conditions will continue inland through Saturday as
the offshore pattern continues. Some RH recovery is expected over
coastal areas, but inland, minimum RH values will continue below 15
percent through Saturday. Some increase in offshore flow is
expected both Fri/Sat with diurnal (morning/midday) peak wind
gusts below critical levels, except in isolated offshore wind-prone
spots. Still, the combination of very low RH, weak to moderate
offshore winds, and above average temperatures will maintain
elevated fire weather concerns through at least Saturday.
Improvements are slated for Sunday as onshore flow and RH increase.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...Gregoria (Update)/JAD (Prev Discussion)
AVIATION/MARINE...JJT