Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 05/17/16
Area Forecast Discussion
National Weather Service Flagstaff AZ
357 PM MST MON MAY 16 2016
.SYNOPSIS...A low pressure system moving south through the western
states will bring showers and thunderstorms to northern Arizona
starting this afternoon. On Tuesday and Wednesday, the low moves
into Arizona, expect increasing shower and thunderstorm activity
spreading deeper into central Arizona. By Thursday shower activity
will diminish and be limited the the mountain areas with the best
chances for measurable rain over the White Mountains region in
eastern Arizona. Dry weather will return from Friday into the
weekend with good chances for advisory level winds on Friday
afternoon.
&&
.DISCUSSION...A cold low pressure system is currently diving south
through the western states. Today`s showers and thunderstorms were
but a taste of the leading edge of this storm. On Tuesday and
Wednesday this low moves into northern Arizona with numerous
showers and thunderstorms expanding further into central Arizona.
Shower and storm activity will continue into the overnight hours
as the instability and lift associated with the upper low will be
strong enough to overcome typical nocturnal surface cooling
effects that otherwise cause convection to decrease diurnally.
Afternoon temperatures will also be around 10 degrees colder than
normal for this time of year. We are forecasting around 0.25
inches of rainfall over our mountain regions.
The main impacts with this system will be wet roads, occasional
erratic gusty winds and small hail. The probability for flooding
or severe thunderstorms is low.
By Thursday the low will move eastward away from the state with
lingering chances for showers and afternoon thunderstorms mainly
over mountain areas. The best chances for measurable precipitation
will be in the White Mountains region on Thursday afternoon.
Friday through Sunday...Another seasonably strong low pressure
system sets up over the Pacific Northwest. This low will remain
too far north of Arizona to bring us much in the way of
precipitation. However the position of the low will increase our
surface pressure gradients leading to stronger winds. The
strongest winds for this period will develop on Friday with good
chances that our Friday afternoon wind gusts will exceed our wind
advisory thresholds.
&&
.AVIATION...For the 00Z package...TIL 02Z...expect scattered
-shra/-tsra coverage north of I-40 with isolated coverage south of
I-40. MVFR cig/vis possible. Erratic outflow wind gusts to 40kt
possible near precip shafts. Otherwise sfc winds SW-W 15-25 kts.
Btwn 02z-15Z Tues VFR with light winds. Aft 15z tues, sct
-shra/-tsra developing across northern AZ. Aviation discussion not
updated for TAF amendments.
&&
.FIRE WEATHER...A slow moving upper level low will bring
moisture and very good chances for showers and thunderstorms to
northern Arizona from Tuesday through Wednesday evening. Max temps
to be around 10 degrees below normal.
Thursday through Saturday...Chances for showers and thunderstorms
decrease from west to east on Thursday. Dry weather and increasing
south to southwest winds will return Friday and Saturday.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...Bohlin
AVIATION...DL
FIRE WEATHER...DL
For Northern Arizona weather information visit
weather.gov/flagstaff
[top]
Area Forecast Discussion
National Weather Service Phoenix AZ
255 PM MST MON MAY 16 2016
.SYNOPSIS...
A large Pacific low pressure system is expected to move south from
Idaho, and into Arizona late Tuesday through Wednesday. Increasing
clouds with a chance of showers and thunderstorms are forecast to
spread from southeast California and southwest Arizona late Tuesday
afternoon, into south central Arizona Tuesday night and Wednesday.
Clearing is expected Wednesday night, with dry weather and near
normal temperatures developing toward the end of the work week and
weekend.
&&
.DISCUSSION...
Tonight through Wednesday Night...
An interesting weather pattern will develop over the region the next
few days. A large former Pacific low pressure system, centered over
southwest Idaho since Sunday, will start to move south toward AZ.
Strong ridge building along the Pacific northwest coast, folding
over into southwest Canada, bodes well for the Idaho trof to
retrograde and track southwest into southern CA Tuesday and Tuesday
night. Mid/hi level cyclonic shear will increase the potential for
showers and thunderstorms, with increasing moisture. The San Diego
sounding showed some appreciable low level moisture, and the
Chihuahua Mexico balloon sounding showed a hint of a significant
moisture plume visible south of the border in precip water satellite
imagery. Lastly, the Phoenix and Tucson Radar VAD Wind Profiles were
already detect backing south to southwest winds under 12 thsd feet.
As the trof deepens from Idaho toward southern CA, low level winds
will continue to back from the south, importing more moisture into
the tight mid/hi level cyclonic circulation feature expected
Tuesday/Tuesday night. In other words, as the trof moves slowly west
to east, a threat of showers and thunderstorms will first develop in
southeast CA/southwest AZ late Tuesday afternoon,then spread into
south central AZ, including Phoenix, Tuesday night and Wednesday.
Clearing is expected Wednesday night.
Thursday and Friday...
In the aftermath of Wednesdays eastward moving trof, dry west to
northwesterly flow will develop Thursday over our forecast area.
The flow aloft will change to dry southwesterly in advance of yet
another large Pacific weather system expected to develop
However another Large Pacific weather system will settle into the
western states this weekend, producing gusty south to southwest
winds area-wide Fri, Sat, Sun, and Mon afternoons.
&&
.AVIATION...
South-Central Arizona including KPHX...KIWA and KSDL...
No aviation weather impacts expected through Tuesday afternoon.
Southeasterly flow will veer to westerly this afternoon, peaking
around 10 kt with occasional gusts to around 15 kt. Onset of
the downslope easterly flow will occur near the climatological
average of 09-10z.
Southeast California/Southwest Arizona including KIPL and KBLH...
Typical diurnal winds expected at the terminals, generally less than
15 kt at KIPL and KBLH. Looking ahead, scattered showers and
thunderstorms will likely develop ahead of an approaching low
pressure system Tuesday afternoon. The strongest storms will be
capable of producing strong downdraft winds.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Wednesday through Sunday...
An upper level low will begin weakening on Wednesday with just a
slight chance of showers and thunderstorms east of the Lower
Colorado River Valley. Temperatures will be below normal over south-
central AZ and at or slightly above normal across southeast
California and southwest Arizona. The system exits on Thursday for
warmer temperatures and increasing winds. Another system slowly
approaches from the northwest Friday into Sunday for breezy to windy
conditions each day and a cooling trend. Minimum humidities will
generally be in the 15-20 percent range over the lower deserts
through Thursday before declining to near 10 percent by Friday.
Friday afternoon, and possibly Saturday afternoon, will likely have
elevated fire danger conditions over portions of the area.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Vasquez
AVIATION...Hirsch
FIRE WEATHER...Kuhlman
Area Forecast Discussion
National Weather Service Phoenix AZ
605 AM MST MON MAY 16 2016
.UPDATE...Updated Aviation and Fire Weather Discussions...
&&
.SYNOPSIS...
Cooler air is beginning to move into the region as a Pacific low
pressure system in the northwest U.S. begins to deepen and sag
further south. The Pacific low is forecast to move into the
southwestern states early this week persisting through Wednesday.
This will provide even cooler temperatures along with slight chances
of showers and thunderstorms Tuesday. Clearing skies with rebounding
temperatures are forecast for late in the week.
&&
.DISCUSSION...
Broad upper low circulation covers much of the Intermountain West
this early morning with a few well-defined embedded vorticies along a
weak upper jet intrusion on the western side of the low. This low
pressure system will be the focus on our weather for the early part
of the week, bringing a temperature cool down and shower/thunderstorm
chances across the forecast area. Overnight skies remain clear and
winds have subsided from their elevated westerly breezes last
evening. Continued draw-down of UL heights and few degrees of cooling
through the atmo profile transitioning into the area from yesterday`s
cool front have generated cooler morning temperatures so far,
generally 4 to 5 degrees cooler than this time Sunday. Dry
conditions, afternoon southwesterly breezes and temperatures over the
Deserts in the upper 80s to low 90s are expected today ahead of the
southward sagging Great Basin upper low.
Forecast model consistency has been fairly good with regards to this
upper low - still tracking the main circulation center west across
SoCal by Tuesday afternoon and into central AZ overnight Tuesday into
Wednesday. 500mb heights have already retreated from their higher
values late last week so the height fall differential with the
intruding upper low is not as great as previous events we`ve seen
this Spring. PWAT forecasts on model plots and soundings have flirted
with 0.75 to 1.00 inch values, focused mainly along and either side
of the CO River Valley by Tuesday evening. When comparing these
values to soundings from neighboring offices of Tucson and Las Vegas
these forecast values are in the upper reaches of PWAT sounding
climatology. Also hard not imagine some Gulf of California moisture
advection into the region with southerly flow up the river;
dewpoints for sites along the River have touched the 50F mark
periodically over the weekend. While that is more surface based
moisture, a thin layer of mid-level moisture returns are also
forecast. These are most noticeable in several inverted-V soundings
for KBLH, KPHX and Wickenburg. SREF plume forecasts do generate a few
hundred joules of mean MU and ML CAPE for Tuesday afternoon and
overnight, in conjunction with the overhead passage of the upper
cold core. Forecast 500mb and 300mb temperatures in the -16 to -17C
and -40 to -44C ranges respectively. Still not an overly favorable
profile to support organized convection in terms of wind and we`ll be
looking for the dry sub-cloud layer to enhance evaporative processes
leading to gusty outflow winds from any showers and storms that do
develop. Given the latest guidance suggesting 1) sufficient moisture
for some high-based activity across the western AZ deserts and 2) hi-
resolution gridded wind fields indicating some outflow boundary
activity emanating from the western AZ deserts, felt that slightly
boosting PoPs across La Paz and western Maricopa counties for Tuesday
afternoon and evening was warranted.
With varying periods of partly to mostly cloudy skies, the South-
Central AZ Deserts can expect a few more degrees of cooling off high
temperatures from today for Tuesday and Wednesday, with widespread
80-degree readings. Tuesday will be cool for most, including
locations west of the CO River Valley with some warming back into the
90s possible by Wednesday. The loosely cut-off system will begin to
become more of an open wave as it clear east of the area overnight
Wednesday, with some slight chances lingering for spotty
thundershower activity over the eastern AZ higher terrain for
Wednesday and Thursday afternoons. For the rest of the forecast area
from Phoenix, Blythe, Gila Bend, Yuma and El Centro - conditions
will slowly warm back up to near-normal values as very short-lived
ridging passes through the area peaking 1000-500mb thicknesses back
into the mid 570dm range.
Upper level pattern remains active and progressive across the West
for the coming weekend as a broader and deeper Pacific low moves down
the West Coast out of B.C. and the Gulf of Alaska. Beginning
Friday, deep southerly flow filters in across much of the Southwest
states allow for healthy WAA and prolonged warming of temperatures in
spite of the gradually lower UL heights in troughing upstream. What
remained uncertain over previous forecast periods was the southward
extent of the low. It appears now that the main circulation and cold
core stays to our north across the Great Basin. Downstream ridging
would lend us to think the Pacific low would dive further south over
the weekend, but it now looks like ridging over the Plains will
weaken while another upstream Pacific low transitions out of the Gulf
of Alaska late Saturday. This should shift the Great Basin Low over
the Rockies. All-in-all, some variant of troughing will generally
hold over the west with several periods of breezy to gusty winds for
the coming weekend and into early next week. Temperatures shouldn`t
see a significant cool-down, but rather just below mid-May normals
with many lower elevations sites a degree or two either side of 90F.
&&
.AVIATION...
South-Central Arizona including KPHX...KIWA and KSDL...
Southeast California/Southwest Arizona including KIPL and KBLH...
Light winds this morning will turn westerly and become breezy at
times this afternoon, mainly at Phoenix area terminals. Dry westerly
flow aloft will keep skies mainly clear into early Tuesday before
the next weather system moves into the region bringing a chance of
showers and thunderstorms later Tuesday.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Wednesday through Sunday...
An upper level low will begin weakening on Wednesday with just a
slight chance of showers and thunderstorms east of the Lower
Colorado River Valley. Temperatures will be below normal over south-
central AZ and at or slightly above normal across southeast
California and southwest Arizona. The system exits on Thursday for
warmer temperatures and increasing winds. Another system slowly
approaches from the northwest Friday into Sunday for breezy to windy
conditions each day and a cooling trend. Minimum humidities will
generally be in the 15-20 percent range over the lower deserts
through Thursday before declining to near 10 percent by Friday.
Friday afternoon, and possibly Saturday afternoon, will likely have
elevated fire danger conditions over portions of the area.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Nolte
AVIATION...Kuhlman
FIRE WEATHER...Kuhlman
Area Forecast Discussion
National Weather Service Flagstaff AZ
358 AM MST MON MAY 16 2016
.SYNOPSIS...Expect breezy west southwest winds today, along with
an increasing chance of showers and thunderstorms by afternoon. A
slow moving storm system will keep a chance of showers and
thunderstorms over the area through at least Thursday.
Temperatures will be below average through midweek and then warm
back to around average second half of the week. &&
.DISCUSSION...A large area of low pressure over the western states will
continue to move southward today...and be over the area Tuesday
and Wednesday. Best chances for showers today will primarily be
north of I-40...with the best lift and instability.
Tuesday and Wednesday...The area of low pressure will drop
southward into portions of northwest and central Arizona on
Tuesday...and then be over the region on Wednesday. Stronger
lift...deeper saturation...and instability will provide for good
chances of showers and thunderstorms. Rainfall amounts look to be
from 0.1 to 0.5 inches with this system, lighter amounts expected
for the lower elevations
Thursday northern Arizona is forecast to transition from a low
pressure trough back to a high pressure ridge pattern, bringing
drier conditions and warming daytime temperatures.
Friday through Sunday...Another low pressure trough is forecast
to approach northern Arizona from the west, producing a dry and
windy southwest flow.
By Monday of next week the low pressure trough is forecast to
move across Arizona...bringing lighter winds...drying
conditions...and slightly below average daytime temperatures.
&&
.AVIATION...For the 12Z package...Expect VFR conditions overnight.
After 18Z Mon...expect isolated to scattered SHRA/TSRA primarily
along and north of a KFLG-KRQE line with brief MVFR cig/vis
possible. Winds becoming westerly Mon afternoon 15-25 kts. In
addition, collapsing TSRA may produce very strong and erratic
surface winds with gusts as high as 50 knots possible in the
vicinity of storms. Aviation discussion not updated for TAF
amendments.
.FIRE WEATHER...A slow moving low will bring increasing moisture
and increasing chances for showers and thunderstorms to northern
Arizona on Monday and Tuesday.
Wednesday through Friday...Chances for showers and thunderstorms
continue through Wednesday with a drying trend starting from
Thursday onward.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...TC
AVIATION...RR
FIRE WEATHER...RR
For Northern Arizona weather information visit
weather.gov/flagstaff
Area Forecast Discussion
National Weather Service Phoenix AZ
314 AM MST MON MAY 16 2016
.SYNOPSIS...
Cooler air is beginning to move into the region as a Pacific low
pressure system in the northwest U.S. begins to deepen and sag
further south. The Pacific low is forecast to move into the
southwestern states early this week persisting through Wednesday.
This will provide even cooler temperatures along with slight chances
of showers and thunderstorms Tuesday. Clearing skies with rebounding
temperatures are forecast for late in the week.
&&
.DISCUSSION...
Broad upper low circulation covers much of the Intermountain West
this early morning with a few well-defined embedded vorticies along a
weak upper jet intrusion on the western side of the low. This low
pressure system will be the focus on our weather for the early part
of the week, bringing a temperature cool down and shower/thunderstorm
chances across the forecast area. Overnight skies remain clear and
winds have subsided from their elevated westerly breezes last
evening. Continued draw-down of UL heights and few degrees of cooling
through the atmo profile transitioning into the area from yesterday`s
cool front have generated cooler morning temperatures so far,
generally 4 to 5 degrees cooler than this time Sunday. Dry
conditions, afternoon southwesterly breezes and temperatures over the
Deserts in the upper 80s to low 90s are expected today ahead of the
southward sagging Great Basin upper low.
Forecast model consistency has been fairly good with regards to this
upper low - still tracking the main circulation center west across
SoCal by Tuesday afternoon and into central AZ overnight Tuesday into
Wednesday. 500mb heights have already retreated from their higher
values late last week so the height fall differential with the
intruding upper low is not as great as previous events we`ve seen
this Spring. PWAT forecasts on model plots and soundings have flirted
with 0.75 to 1.00 inch values, focused mainly along and either side
of the CO River Valley by Tuesday evening. When comparing these
values to soundings from neighboring offices of Tucson and Las Vegas
these forecast values are in the upper reaches of PWAT sounding
climatology. Also hard not imagine some Gulf of California moisture
advection into the region with southerly flow up the river;
dewpoints for sites along the River have touched the 50F mark
periodically over the weekend. While that is more surface based
moisture, a thin layer of mid-level moisture returns are also
forecast. These are most noticeable in several inverted-V soundings
for KBLH, KPHX and Wickenburg. SREF plume forecasts do generate a few
hundred joules of mean MU and ML CAPE for Tuesday afternoon and
overnight, in conjunction with the overhead passage of the upper
cold core. Forecast 500mb and 300mb temperatures in the -16 to -17C
and -40 to -44C ranges respectively. Still not an overly favorable
profile to support organized convection in terms of wind and we`ll be
looking for the dry sub-cloud layer to enhance evaporative processes
leading to gusty outflow winds from any showers and storms that do
develop. Given the latest guidance suggesting 1) sufficient moisture
for some high-based activity across the western AZ deserts and 2) hi-
resolution gridded wind fields indicating some outflow boundary
activity emanating from the western AZ deserts, felt that slightly
boosting PoPs across La Paz and western Maricopa counties for Tuesday
afternoon and evening was warranted.
With varying periods of partly to mostly cloudy skies, the South-
Central AZ Deserts can expect a few more degrees of cooling off high
temperatures from today for Tuesday and Wednesday, with widespread
80-degree readings. Tuesday will be cool for most, including
locations west of the CO River Valley with some warming back into the
90s possible by Wednesday. The loosely cut-off system will begin to
become more of an open wave as it clear east of the area overnight
Wednesday, with some slight chances lingering for spotty
thundershower activity over the eastern AZ higher terrain for
Wednesday and Thursday afternoons. For the rest of the forecast area
from Phoenix, Blythe, Gila Bend, Yuma and El Centro - conditions
will slowly warm back up to near-normal values as very short-lived
ridging passes through the area peaking 1000-500mb thicknesses back
into the mid 570dm range.
Upper level pattern remains active and progressive across the West
for the coming weekend as a broader and deeper Pacific low moves down
the West Coast out of B.C. and the Gulf of Alaska. Beginning
Friday, deep southerly flow filters in across much of the Southwest
states allow for healthy WAA and prolonged warming of temperatures in
spite of the gradually lower UL heights in troughing upstream. What
remained uncertain over previous forecast periods was the southward
extent of the low. It appears now that the main circulation and cold
core stays to our north across the Great Basin. Downstream ridging
would lend us to think the Pacific low would dive further south over
the weekend, but it now looks like ridging over the Plains will
weaken while another upstream Pacific low transitions out of the Gulf
of Alaska late Saturday. This should shift the Great Basin Low over
the Rockies. All-in-all, some variant of troughing will generally
hold over the west with several periods of breezy to gusty winds for
the coming weekend and into early next week. Temperatures shouldn`t
see a significant cool-down, but rather just below mid-May normals
with many lower elevations sites a degree or two either side of 90F.
&&
.AVIATION...
South-Central Arizona including KPHX...KIWA and KSDL...
Southeast California/Southwest Arizona including KIPL and KBLH...
Gusty westerly winds to continue to gradually diminish through the
rest of the evening and overnight hours as stronger winds aloft
become decoupled from the surface. wind directions to become
easterly later tonight at the phx area taf sites, while KBLH remains
out of a southerly to sw-ly direction, and KIPL out of a westerly
direction. After a period of light winds on Monday morning, stronger
westerly winds to develop Monday afternoon at the phx area taf sites
and at KIPL as stronger winds once again mix down to the sfc, with
KBLH seeing winds picking up from a southerly direction. Dry
westerly flow aloft to keep skies mainly clear through monday at all
of the taf sites.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Wednesday through Sunday...
An upper level low will begin weakening on Wednesday with just a
slight chance of showers and thunderstorms (east of the Lower
Colorado River Valley). Temperatures will be below normal over
south-central AZ (at or slightly above normal west of there). Winds
will be light. The system exits on Thursday for warmer temperatures
and more noticeable afternoon breezes. Another system slowly
approaches from the northwest Friday into Sunday for breezy
conditions (especially southeast California) and a cooling trend.
Minimum humidities will generally be in the 15-20 percent range on
the lower deserts before declining to near 10 percent by Friday.
Overnight recovery also trends down but remains fair. Portions of
southeast California and the Lower Colorado River Valley may
occasionally flirt with critical thresholds during the Friday-Sunday
time frame.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Nolte
AVIATION...Percha
FIRE WEATHER...AJ
[top]
Area Forecast Discussion
National Weather Service Tucson AZ
257 AM MST MON MAY 16 2016
.SYNOPSIS...A low pressure system will move south into the desert
southwest by midweek. Cooler temperatures will occur through Tuesday
followed by isolated to scattered thunderstorms from Tucson eastward
Wednesday. A chance of showers continues across the White mountains
Thursday, then dry conditions with warmer temperatures next weekend.
&&
.DISCUSSION...Breezy conditions again today across far southeast
Arizona. Otherwise...mostly clear skies and cooler afternoon
temperatures can be anticipated. Models continued to track a low
pressure system south into northwest Arizona on Tuesday. Moisture
associated with this system appeared to be limited but enough to
warrant the mention of a few showers and thunderstorms Tuesday into
Thursday. The best chance of showers will be across northern and
eastern sections of the state. Cooler air will also accompany this
system with high temperatures lowering to near normal readings this
week. Thereafter, medium range models showed a ridge of high
pressure building over the desert southwest followed by another
storm system which will bring breezy to windy conditions this
weekend.
&&
.AVIATION...VALID THRU 17/12Z.
Clear skies and VFR conditions will prevail through the forecast
period. Surface wind less than 10 kts thru 16/14z...then increasing
surface wind. Sly/swly surface wind at 15-25 kts and gusts to 23-33
kts by 16/19z...with the strongest surface wind east of KTUS in the
vicinity of KALK, KFHU and especially KDUG. Surface wind diminishing
aft 17/02z and generally less than 10 kts by 17/05z. Aviation
discussion not updated for TAF ammendments.
&&
.FIRE WEATHER.... Breezy conditions will persist today across the far
southeastern corner of southeast Arizona...roughly southeast of a
line from the Huachuca mountains to the Chiricahua mountains in
Cochise county. Critical fire weather thresholds may be briefly
exceeded in this area this afternoon. However, widespread conditions
are not expected and therefore no fire weather headlines will be in
effect. Less wind is expected elsewhere across the forecast area
today, along with dry and cooler conditions.
There will be a slight chance of showers and thunderstorms Tuesday
into Thursday, mainly northeast and east of the Tucson metro area.
The best chance of precipitation will be in the White mountains.
Some afternoon breeziness is expected through the upcoming week,
mainly on Tuesday and then again Friday into Sunday of next weekend.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion
National Weather Service Phoenix AZ
1030 PM MST SUN MAY 15 2016
.UPDATE...To Aviation Discussion...
&&
.SYNOPSIS... Cooler air is beginning to move into the region as a
Pacific low pressure system in the northwest U.S. begins to deepen
and sag further south. The Pacific low is forecast to move into the
southwestern states early this week persisting through Wednesday.
This will provide even cooler temperatures along with slight chances
of showers and thunderstorms Tuesday. Clearing skies with rebounding
temperatures are forecast for late in the week.
&&
.DISCUSSION...
upper low pressure, that is now moving into the northern Great
Basin, has begun to bring cooler temperatures to the region today,
with the high at Phoenix Sky Harbor ending up at 95 today, down 6
degrees from yesterday`s high of 101. Along with the cooler
temperatures, locally gusty winds also occurred today as the winds
aloft increase ahead of the upper low. westerly winds in the 15-20
mph range with gusts to 30 mph were observed at many locations
across South-Central and SW Arizona, with even stronger winds over
parts of SE CA. Along with the winds, a few pockets of blowing dust
were also observed. The latest (00z) GFS and NAM model suites
continue to show the upper low moving toward the region through the
early and middle parts of this week, with temperatures cooling even
further, and even a chance for showers from late Tuesday into
Wednesday, as the upper low center moves across the region. As far
as the very short term is concerned, other then some downward
adjustment in the hourly dewpoint forecasts and some minor
adjustments to the other hourly grids, inherited forecasts are
holding up well.
&&
.PREVIOUS DISCUSSION...
Upper low across the Great Basin continues to drift eastward this
afternoon. Latest satellite imagery shows widespread cloudiness out
ahead of this system across the Rockies with a smattering of showers
and thunderstorms extending southward into Chihuahua. Across the
desert southwest, skies have been mostly clear with temperatures in
the lower 90s across the lower deserts, a drop of roughly 6 to 8 from
those observed yesterday. Dewpoints are also significantly lower east
of Phoenix, though moisture is already increasing again across
western Arizona ahead of a vort max traversing the Mojave Desert.
This vort max will also strengthen wind fields across the region and
breezy conditions are anticipated through this evening across much of
the area.
No major changes were made to the forecast in the short-term.
Temperatures tonight will be near or slightly above average with
subsiding winds and mostly clear skies.
&&
.PREVIOUS DISCUSSION...
The upper low eventually will start to dig southward through the
Great Basin on Monday into the Desert Southwest on Tuesday. Models
have been consistent with the overall track of this system, but have
shifted it further west slightly over the past 24 hours. Some
moisture advection is expected over our area Tuesday into early
Wednesday with PWATS increasing to between 0.50-0.75 inches. Though
this system is not very cold aloft (500mb temps near -16C) there
should be sufficient moisture and instability for some isolated
showers and thunderstorms starting Tuesday afternoon. Overall timing
has shifted a bit later, so rain chances will linger into Wednesday,
especially from Phoenix eastward. Have added in slight chance POPs
across south-central Arizona for Tuesday night and Wednesday morning
with chances remaining through Wednesday evening across the higher
terrain east of Phoenix. We could see a shot at some gusty thunderstorm
winds with an inverted V forecast sounding structure, but winds aloft
will be light, so would only rely on evaporative cooling effects.
Temperatures through Wednesday are forecast to be at or below normals
with Monday and Tuesday being the coolest days with highs mostly in
the upper 80s across the lower deserts. We will start to see some
warming across our western zones on Wednesday under rising heights
aloft as highs climb back into the middle 90s.
Model consensus continues to show a deep Pacific low digging
southward into the Pacific Northwest late this week, but what happens
thereafter is less certain as model spread increases into next
weekend. For the Desert Southwest, heights aloft and temperatures
will certainly rise on Thursday and Friday resulting in highs at or
just above normals (middle to upper 90s). Have low confidence in the
forecast picture for next weekend as it is not clear if the Pacific
low will dig far enough south to affect the Desert Southwest.
&&
.AVIATION...
South-Central Arizona including KPHX...KIWA and KSDL...
Southeast California/Southwest Arizona including KIPL and KBLH...
Gusty westerly winds to continue to gradually diminish through the
rest of the evening and overnight hours as stronger winds aloft
become decoupled from the surface. wind directions to become
easterly later tonight at the phx area taf sites, while KBLH remains
out of a southerly to sw-ly direction, and KIPL out of a westerly
direction. After a period of light winds on Monday morning, stronger
westerly winds to develop Monday afternoon at the phx area taf sites
and at KIPL as stronger winds once again mix down to the sfc, with
KBLH seeing winds picking up from a southerly direction. Dry
westerly flow aloft to keep skies mainly clear through monday at all
of the taf sites.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Wednesday through Sunday...
An upper level low will begin weakening on Wednesday with just a
slight chance of showers and thunderstorms (east of the Lower
Colorado River Valley). Temperatures will be below normal over
south-central AZ (at or slightly above normal west of there). Winds
will be light. The system exits on Thursday for warmer temperatures
and more noticeable afternoon breezes. Another system slowly
approaches from the northwest Friday into Sunday for breezy
conditions (especially southeast California) and a cooling trend.
Minimum humidities will generally be in the 15-20 percent range on
the lower deserts before declining to near 10 percent by Friday.
Overnight recovery also trends down but remains fair. Portions of
southeast California and the Lower Colorado River Valley may
occasionally flirt with critical thresholds during the Friday-Sunday
time frame.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Percha/Hirsch
PREVIOUS DISCUSSION...Kuhlman
AVIATION...Percha
FIRE WEATHER...AJ
Area Forecast Discussion
National Weather Service Phoenix AZ
900 PM MST SUN MAY 15 2016
.UPDATE...
Updated Aviation and Fire Weather sections.
&&
.SYNOPSIS... Cooler air is beginning to move into the region as a
Pacific low pressure system in the northwest U.S. begins to deepen
and sag further south. The Pacific low is forecast to move into the
southwestern states early this week persisting through Wednesday.
This will provide even cooler temperatures along with slight chances
of showers and thunderstorms Tuesday. Clearing skies with rebounding
temperatures are forecast for late in the week.
&&
.DISCUSSION...
upper low pressure, that is now moving into the northern Great
Basin, has begun to bring cooler temperatures to the region today,
with the high at Phoenix Sky Harbor ending up at 95 today, down 6
degrees from yesterday`s high of 101. Along with the cooler
temperatures, locally gusty winds also occurred today as the winds
aloft increase ahead of the upper low. westerly winds in the 15-20
mph range with gusts to 30 mph were observed at many locations
across South-Central and SW Arizona, with even stronger winds over
parts of SE CA. Along with the winds, a few pockets of blowing dust
were also observed. The latest (00z) GFS and NAM model suites
continue to show the upper low moving toward the region through the
early and middle parts of this week, with temperatures cooling even
further, and even a chance for showers from late Tuesday into
Wednesday, as the upper low center moves across the region. As far
as the very short term is concerned, other then some downward
adjustment in the hourly dewpoint forecasts and some minor
adjustments to the other hourly grids, inherited forecasts are
holding up well.
&&
.PREVIOUS DISCUSSION...
Upper low across the Great Basin continues to drift eastward this
afternoon. Latest satellite imagery shows widespread cloudiness out
ahead of this system across the Rockies with a smattering of showers
and thunderstorms extending southward into Chihuahua. Across the
desert southwest, skies have been mostly clear with temperatures in
the lower 90s across the lower deserts, a drop of roughly 6 to 8 from
those observed yesterday. Dewpoints are also significantly lower east
of Phoenix, though moisture is already increasing again across
western Arizona ahead of a vort max traversing the Mojave Desert.
This vort max will also strengthen wind fields across the region and
breezy conditions are anticipated through this evening across much of
the area.
No major changes were made to the forecast in the short-term.
Temperatures tonight will be near or slightly above average with
subsiding winds and mostly clear skies.
&&
.PREVIOUS DISCUSSION...
The upper low eventually will start to dig southward through the
Great Basin on Monday into the Desert Southwest on Tuesday. Models
have been consistent with the overall track of this system, but have
shifted it further west slightly over the past 24 hours. Some
moisture advection is expected over our area Tuesday into early
Wednesday with PWATS increasing to between 0.50-0.75 inches. Though
this system is not very cold aloft (500mb temps near -16C) there
should be sufficient moisture and instability for some isolated
showers and thunderstorms starting Tuesday afternoon. Overall timing
has shifted a bit later, so rain chances will linger into Wednesday,
especially from Phoenix eastward. Have added in slight chance POPs
across south-central Arizona for Tuesday night and Wednesday morning
with chances remaining through Wednesday evening across the higher
terrain east of Phoenix. We could see a shot at some gusty thunderstorm
winds with an inverted V forecast sounding structure, but winds aloft
will be light, so would only rely on evaporative cooling effects.
Temperatures through Wednesday are forecast to be at or below normals
with Monday and Tuesday being the coolest days with highs mostly in
the upper 80s across the lower deserts. We will start to see some
warming across our western zones on Wednesday under rising heights
aloft as highs climb back into the middle 90s.
Model consensus continues to show a deep Pacific low digging
southward into the Pacific Northwest late this week, but what happens
thereafter is less certain as model spread increases into next
weekend. For the Desert Southwest, heights aloft and temperatures
will certainly rise on Thursday and Friday resulting in highs at or
just above normals (middle to upper 90s). Have low confidence in the
forecast picture for next weekend as it is not clear if the Pacific
low will dig far enough south to affect the Desert Southwest.
&&
.AVIATION...
South-Central Arizona including KPHX...KIWA and KSDL...
Southeast California/Southwest Arizona including KIPL and KBLH...
Dry cool front passing across the deserts this afternoon and evening.
Expect southwest winds to prevail through the evening before
starting to become light and variable. Gusts of 20-25 kts will be
common through 02Z before weakening. However, the Imperial valley
will have stronger gusts (30-35 kts) through 04Z before beginning to
weaken. Could see some local blowing dust/sand there but confidence
not high enough to reflect in KIPL TAF. Winds will be lighter on
Monday afternoon. Otherwise, no significant cloudiness.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Wednesday through Sunday...
An upper level low will begin weakening on Wednesday with just a
slight chance of showers and thunderstorms (east of the Lower
Colorado River Valley). Temperatures will be below normal over
south-central AZ (at or slightly above normal west of there). Winds
will be light. The system exits on Thursday for warmer temperatures
and more noticeable afternoon breezes. Another system slowly
approaches from the northwest Friday into Sunday for breezy
conditions (especially southeast California) and a cooling trend.
Minimum humidities will generally be in the 15-20 percent range on
the lower deserts before declining to near 10 percent by Friday.
Overnight recovery also trends down but remains fair. Portions of
southeast California and the Lower Colorado River Valley may
occasionally flirt with critical thresholds during the Friday-Sunday
time frame.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Percha/Hirsch
PREVIOUS DISCUSSION...Kuhlman
AVIATION...AJ
FIRE WEATHER...AJ
Area Forecast Discussion
National Weather Service Phoenix AZ
221 PM MST SUN MAY 15 2016
.SYNOPSIS... Cooler air is beginning to move into the region as a
Pacific low pressure system in the northwest U.S. begins to deepen
and sag further south. The Pacific low is forecast to move into the
southwestern states early this week persisting through Wednesday.
This will provide even cooler temperatures along with slight chances
of showers and thunderstorms Tuesday. Clearing skies with rebounding
temperatures are forecast for late in the week.
&&
.DISCUSSION...
Upper low across the Great Basin continues to drift eastward this
afternoon. Latest satellite imagery shows widespread cloudiness out
ahead of this system across the Rockies with a smattering of showers
and thunderstorms extending southward into Chihuahua. Across the
desert southwest, skies have been mostly clear with temperatures in
the lower 90s across the lower deserts, a drop of roughly 6 to 8 from
those observed yesterday. Dewpoints are also significantly lower east
of Phoenix, though moisture is already increasing again across
western Arizona ahead of a vort max traversing the Mojave Desert.
This vort max will also strengthen wind fields across the region and
breezy conditions are anticipated through this evening across much of
the area.
No major changes were made to the forecast in the short-term.
Temperatures tonight will be near or slightly above average with
subsiding winds and mostly clear skies.
&&
.PREVIOUS DISCUSSION...
The upper low eventually will start to dig southward through the
Great Basin on Monday into the Desert Southwest on Tuesday. Models
have been consistent with the overall track of this system, but have
shifted it further west slightly over the past 24 hours. Some
moisture advection is expected over our area Tuesday into early
Wednesday with PWATS increasing to between 0.50-0.75 inches. Though
this system is not very cold aloft (500mb temps near -16C) there
should be sufficient moisture and instability for some isolated
showers and thunderstorms starting Tuesday afternoon. Overall timing
has shifted a bit later, so rain chances will linger into Wednesday,
especially from Phoenix eastward. Have added in slight chance POPs
across south-central Arizona for Tuesday night and Wednesday morning
with chances remaining through Wednesday evening across the higher
terrain east of Phoenix. We could see a shot at some gusty thunderstorm
winds with an inverted V forecast sounding structure, but winds aloft
will be light, so would only rely on evaporative cooling effects.
Temperatures through Wednesday are forecast to be at or below normals
with Monday and Tuesday being the coolest days with highs mostly in
the upper 80s across the lower deserts. We will start to see some
warming across our western zones on Wednesday under rising heights
aloft as highs climb back into the middle 90s.
Model consensus continues to show a deep Pacific low digging
southward into the Pacific Northwest late this week, but what happens
thereafter is less certain as model spread increases into next
weekend. For the Desert Southwest, heights aloft and temperatures
will certainly rise on Thursday and Friday resulting in highs at or
just above normals (middle to upper 90s). Have low confidence in the
forecast picture for next weekend as it is not clear if the Pacific
low will dig far enough south to affect the Desert Southwest.
&&
.AVIATION...
South-Central Arizona including KPHX...KIWA and KSDL...
Southeast California/Southwest Arizona including KIPL and KBLH...
Dry cool front will make its way across the region today increasing
winds while promoting less cloud cover. Typical AM wind headings will
transition through south to southwest during the day while increasing
in speed. Gusts in the upper teens to low twenty knot range will be
possible for the Phoenix area terminals and KBLH, while stronger
winds off the mountains are expected for KIPL with gusts at or
greater than 30kts. West winds to linger later into the evening than
usual, losing their gustiness but remaining elevated. One final band
of mid-level clouds will continue to track E-SE with mostly clear
skies filling in behind the exiting SCT-BKN layers by the afternoon
and evening.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Tuesday through Saturday...
A low pressure system will be centered over northwest Arizona on
Tuesday and Wednesday leading to a slight chance of thunderstorms
over south-central Arizona. Temperatures will be below normal with
mostly light winds. The upper low exits Thursday before another
system approaches Friday and Saturday leading to breezy to windy
conditions. Winds, under current forecast guidance, look to be
stronger for the late week system than the one responsible for the
winds over the late weekend and early in the work week. Temperatures
will start off below normal Tuesday and Wednesday before climbing
back to normal by Friday. Humidities begin declining Wednesday with
minimum values dipping to about 10% late in the week.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Hirsch
PREVIOUS DISCUSSION...Kuhlman
AVIATION...Nolte
FIRE WEATHER...Nolte/AJ
Area Forecast Discussion
National Weather Service Phoenix AZ
454 AM MST SUN MAY 15 2016
.UPDATE...To AVIATION and FIRE WEATHER Discussions...
&&
.SYNOPSIS...
Cooler air is beginning to move into the region as a Pacific low
pressure system in the northwest U.S. begins to deepen and sag
further south. Breezy conditions are expected today with highs near
normals. This Pacific low is forecast to move into the southwestern
states tonight persisting through Tuesday. This will provide even
cooler temperatures along with slight chances of showers and
thunderstorms. Clearing skies with rebounding temperatures are
forecast for late in the week.
&&
.DISCUSSION...
Drier air has filtered into Arizona as westerly flow aloft moved in
around the southern fringe of the upper low currently situated across
the Pacific Northwest. This drier air has ended any shower or
thunderstorm chances with mainly clear skies expected today. Lowering
heights aloft will allow for some modest cooling to take place today
and as a result highs should only top out in the lower 90s across the
deserts. A deepening surface low over the Great Basin is increasing
pressure gradients across the Desert Southwest resulting in some
breezy winds currently across southeast California. The gradient
will strengthen later today with breezy to windy southwesterly winds
across the majority of the CWA. Winds will remain below advisory
levels, but some gusts to 35 mph are likely across southeast
California and southern Gila County. Elevated fire danger conditions
for a brief time may be realized across southern Gila County this
afternoon, but not enough to warrant any headlines.
The upper low eventually will start to dig southward through the
Great Basin on Monday into the Desert Southwest on Tuesday. Models
have been consistent with the overall track of this system, but have
shifted it further west slightly over the past 24 hours. Some
moisture advection is expected over our area Tuesday into early
Wednesday with PWATS increasing to between 0.50-0.75 inches. Though
this system is not very cold aloft (500mb temps near -16C) there
should be sufficient moisture and instability for some isolated
showers and thunderstorms starting Tuesday afternoon. Overall timing
has shifted a bit later, so rain chances will linger into Wednesday,
especially from Phoenix eastward. Have added in slight chance POPs
across south-central Arizona for Tuesday night and Wednesday morning
with chances remaining through Wednesday evening across the higher
terrain east of Phoenix. We could see a shot at some gusty thunderstorm
winds with an inverted V forecast sounding structure, but winds aloft
will be light, so would only rely on evaporative cooling effects.
Temperatures through Wednesday are forecast to be at or below normals
with Monday and Tuesday being the coolest days with highs mostly in
the upper 80s across the lower deserts. We will start to see some
warming across our western zones on Wednesday under rising heights
aloft as highs climb back into the middle 90s.
Model consensus continues to show a deep Pacific low digging
southward into the Pacific Northwest late this week, but what happens
thereafter is less certain as model spread increases into next
weekend. For the Desert Southwest, heights aloft and temperatures
will certainly rise on Thursday and Friday resulting in highs at or
just above normals (middle to upper 90s). Have low confidence in the
forecast picture for next weekend as it is not clear if the Pacific
low will dig far enough south to affect the Desert Southwest.
&&
.AVIATION...
South-Central Arizona including KPHX...KIWA and KSDL...
Southeast California/Southwest Arizona including KIPL and KBLH...
Dry cool front will make its way across the region today increasing
winds while promoting less cloud cover. Typical AM wind headings will
transition through south to southwest during the day while increasing
in speed. Gusts in the upper teens to low twenty knot range will be
possible for the Phoenix area terminals and KBLH, while stronger
winds off the mountains are expected for KIPL with gusts at or
greater than 30kts. West winds to linger later into the evening than
usual, losing their gustiness but remaining elevated. One final band
of mid-level clouds will continue to track E-SE with mostly clear
skies filling in behind the exiting SCT-BKN layers by the afternoon
and evening.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Tuesday through Saturday...
A low pressure system will be centered over northwest Arizona on
Tuesday and Wednesday leading to a slight chance of thunderstorms
over south-central Arizona. Temperatures will be below normal with
mostly light winds. The upper low exits Thursday before another
system approaches Friday and Saturday leading to breezy to windy
conditions. Winds, under current forecast guidance, look to be
stronger for the late week system than the one responsible for the
winds over the late weekend and early in the work week. Temperatures
will start off below normal Tuesday and Wednesday before climbing
back to normal by Friday. Humidities begin declining Wednesday with
minimum values dipping to about 10% late in the week.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Kuhlman
AVIATION...Nolte
FIRE WEATHER...Nolte/AJ
Area Forecast Discussion
National Weather Service Phoenix AZ
935 PM MST SAT MAY 14 2016
.SYNOPSIS...
Cooler air is beginning to move into the region as a low pressure
system in the northwest U.S. begins to deepen. Breezy conditions are
expected again for Sunday. Another Pacific weather system is
forecast to move into the southwestern states late Sunday through
Tuesday. This will provide even cooler temperatures along with slight
chances of thunderstorms mainly over northern and central Arizona.
Clearing skies with rebounding afternoon temperatures are forecast
for late next week.
&&
.DISCUSSION...
Clearing skies can be seen across southeastern California and the
western half of Arizona this evening. Earlier, a few thunderstorms
swept over the southeastern third of Arizona but that activity has
dissipated and pushed to the east. Low pressure system now over
Oregon continues to gradually deepen and spread its influence further
to the south. Models indicate this system will eventually drop down
towards the south, ultimately moving into northwest Arizona by
Tuesday evening. This will bring a slight chance for thunderstorms to
the region and keep relatively cooler air in place for a few days.
Rain chances are still on the low side but at least there`s a chance
for unsettled weather, particularly Tuesday afternoon through
Wednesday morning. Temperatures should start to climb back above
normals the rest of the week.
&&
.PREVIOUS DISCUSSION...
Latest satellite imagery shows several areas of cumulus congestus,
mainly concentrated across the Mogollon Rim, the CO Plateau and
portions of southeastern AZ. Isolated showers and thunderstorms have
developed, but are mainly relegated to the higher terrain near
Tucson and Flagstaff. Meanwhile, moisture values are running well
above average with dewpoints in the mid 40s. NAEFS PWAT percentiles
are also running above the 90th percentile, though ground based GPS-
IPW and TPW suggest PWATS are somewhat lower. The relatively moist
conditions have also kept temperatures at bay, which have generally
been running in the mid to upper 90s in the lower deserts. At Sky
Harbor Airport, the high has reached 100 degrees.
Preponderance of hi-res CAMs including the operational and
experimental HRRR continue to indicate that isolated convection will develop
across Gila County this afternoon and this evening. PoPs were increased
to around 10 percent in these areas, though in reality most precipitation
that falls will likely evaporate and not measure at the surface. Models
are in excellent agreement that much drier air will be transported
northeastward this evening and overnight, with the GEFS ensemble
mean indicating PWATS dropping as low as 0.40 inches. Consequently,
showers and thunderstorms will dissipate shortly after sunset.
&&
.AVIATION...
South-Central Arizona including KPHX...KIWA and KSDL...
Southeast California/Southwest Arizona including KIPL and KBLH...
A weak weather disturbance will continue to produce scattered
cumulus and altocumulus with broken-overcast cirrus this afternoon
before thinning out this evening. Over northern and southeastern
Arizona there will be isolated thunderstorms with some additional
weaker showers which will begin dissipating after sunset. Surface
winds will favor south and southwest directions through the evening
(gusts of 15-20 kts Phoenix area; 20-30 kts SE CA and SW AZ). Winds
will be stronger Sunday afternoon but with significantly less
cloudiness.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Tuesday through Saturday...
A low pressure system will be centered over northwest Arizona on
Tuesday and Wednesday leading to a slight chance of thunderstorms
over south-central Arizona. Temperatures will be below normal with
light winds. The low exits Thursday before another system approaches
Friday and Saturday leading to breezy to windy conditions.
Temperatures will start off below normal Tuesday and Wednesday before
climbing back to normal by Friday. Humidities begin declining
Wednesday with Minimum values dipping to about 10% late in the week.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Waters/Hirsch
PREVIOUS DISCUSSION...Kuhlman
AVIATION...AJ
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION...UPDATED
NWS LOS ANGELES/OXNARD CA
604 PM PDT MON MAY 16 2016
Updated aviation section
.SYNOPSIS...
The low will bring the marine layer and near normal temperatures
into Tuesday with a slight chance of showers and thunderstorms in
the mountains and deserts Tuesday afternoon. The offshore flow on
Wednesday and Thursday will reduce clouds and be the hottest days of
the week. Then on Friday a low should arrive for an increase of
the marine layer and a cooling trend into early next week.
&&
.SHORT TERM...(TDY-THU)
An upper low over nrn Nevada will drop slowly south over the next
24-36 hours. As it does, some energy will wrap around it and move
into our area Tuesday afternoon and evening. This combined with
some mid level moisture and instability will generate at least the
threat of an afternoon thunderstorm or two over the LA/Ventura
mtns and Antelope Valley. There`s not a ton of moisture to work
with but enough to warrant a slight chance. Steering flow is from
the north so there is some chance that anything that forms will
drift south into the adjacent foothills and valleys, but chances
are too low to include in the forecast at this time.
Otherwise, a pretty mundane forecast. A brief ridge will pop up
Wed and lead to a little warming trend but still plenty of marine
lyr clouds for coast and valleys, some of which may linger at the
beaches through the afternoon. Models still show some instability
over the mtns and deserts Wed but with little moisture to work
feel that any convective threat is minimal. A trough will start to
move into nrn California Thu and initiate a cooling trend for most
areas except the far interior.
.LONG TERM...(FRI-MON)
The trough will slide south through the state Fri-Sun before
shifting east Monday. Impacts will mostly be cooler temps, more
clouds, mainly from a deeper marine lyr, and stronger onshore
breezes. So after a brief respite May gray will likely be the
dominant player through the weekend, though likely with at least
some breaks in the clouds. One thing to watch is the ECMWF
continues to be more bullish with moisture than the GFS on Sunday
and actually spits out some light precip across SLO county. This
seems an unlikely scenario and decided just add some clouds there
for now. Beyond Sunday there are a fair amount of model
differences in the details, but most agree that this troughy
pattern will continue for several more days.
&&
.AVIATION...17/0000Z.
At 00Z, the marine layer depth was around 4300 feet at KLAX. The
top of the inversion was around 5000 feet with a temperature of 16
degrees Celsius.
IFR to MVFR conditions will spread into coastal and valley
terminals through 13Z. Highest confidence in IFR conditions exist
in terminals north and west of KSBA and for Los Angeles County
Valley terminals. There is an chance of LIFR conditions at
terminals north and west of KSBA between 06Z and 16Z. A slightly
later clearing time is forecast on Tuesday, with VFR conditions
possibly lingering until around 21Z at coastal terminals.
KLAX...VFR conditions are expected through at least 03z, then MVFR
conditions will spread in through 08Z. VFR conditions should
redevelop between 19Z and 21Z. Due to the eddy circulation, there
is a 30 percent chance of east winds greater than 7 knots between
10Z and 16Z.
KBUR...VFR conditions are expected through 08Z, then IFR
conditions should spread in between 07Z and 10Z. There is a 30
percent chance that IFR conditions could be MVFR. MVFR conditions
could develop by 16Z at the latest. VFR conditions should develop
around 18Z.
&&
.MARINE...16/100 PM.
Moderate confidence that Gale Force winds are finished for at
least the next few days...though occasional gusts between 30 and
35 KT are possible tonight near Point Conception. Moderate
confidence in small craft advisory winds from the Central Coast to
San Nicolas Island through early Tuesday morning. with much
lighter winds tomorrow and Wednesday. Expecting southeast winds to
be prevalent south of Point Conception this morning and Tuesday
morning with local gusts to 15 KT possible in the San Pedro
Channel and the Anacapa Passage. Choppy Short period waves likely
everywhere into Tuesday...with improvement expected after.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 9 PM PDT this evening
For zone 645. (See LAXMWWLOX).
Small Craft Advisory in effect until 9 AM PDT Tuesday For
zones 670-673-676. (See LAXMWWLOX).
&&
$$
PUBLIC...MW
AVIATION...Hall
MARINE...Kittell
SYNOPSIS...Seto
weather.gov/losangeles
[top]
Area Forecast Discussion
National Weather Service Reno NV
301 PM PDT MON MAY 16 2016
.SYNOPSIS...
A few showers are expected this evening across Northwest Nevada as
low pressure slowly pulls away. A warming trend is expected
Tuesday and Wednesday with dry conditions. Another low is expected
late in the week with gusty winds Thursday before more showers are
expected Friday into the weekend.
&&
.SHORT TERM...
A few showers are ongoing across Northwest Nevada this afternoon
with their movement to the southeast. The showers are generally
east of a Alturas to Yerington line and are expected to remain
that way into this evening. There are plenty of clouds west of
this line, but it is more stable with very little vertical
development.
The upper low responsible for these showers is slowly moving south
across Northeast NV and will continue to do so overnight. Expect
showers to diminish with the loss of heating overnight. A few
showers though will remain possible over Mono County Tuesday
morning in the upslope northeast flow behind the low before
clearing in the afternoon.
Temps will slowly warm Tuesday into Wednesday under a short wave
ridge. Wednesday looks to be the warmest day this week before the
next low approaches Thursday. I removed the mention of
showers/thunderstorms for the Sierra Wednesday. GFS/NAM show weak
instability if at all, and the EC is showing no response. The
large scale pattern is not favorable for development and the
atmospheric profile also isn`t favorable for convection due to
heating alone. Wallmann
.LONG TERM...Thursday through Monday...
Unsettled weather pattern will continue into early next week,
with below average temps prevailing after Thursday. The main
changes to the current extended forecast continued the trend of
increasing precip chances north of I-80 late Thursday night thru
Friday evening, and prolonging the cool temps and some precip
chances into early next week.
For Thursday, the main weather effects will be potential for
strong winds ahead of the main low as it drops into the Pacific
Northwest. Tightening pressure and thermal gradients with upper
level jet support and 700 mb flow of 40-45 kt over the Sierra has
been indicated for several days. Therefore confidence is high for
a decent wind event Thursday afternoon-evening especially from
I-80 southward, with possible gusts near 50 mph and Sierra ridge
gusts over 80 mph. Farther north, increased cloud cover and less
favorable jet position should limit wind gusts to 40 mph or less.
Cold front will begin dropping south into northeast CA-northwest
NV and some instability near the front may lead to some late day
thunderstorms, although strong winds aloft could limit convective
development.
The greater chance for precip (with pops increased to likely)
will arrive north of I-80 late Thursday night thru Friday as upper
low center continues pushing farther south into northeast CA. Cold
pool aloft and steep mid-level lapse rates may support some
elevated convection north of Susanville-Gerlach overnight into
early Friday.
For Friday-Saturday, medium range guidance/ensemble data is in
good agreement with cool and showery pattern continuing especially
north of I-80, although increasing precip chances will gradually
spread southward to near US-50 during each afternoon and evening
with possible thunderstorms. Snow levels still could drop to near
6000- 6500 ft from Highway 50 northward, and even down to near
5500 feet in stronger shower bands. The showery nature of the
precip will limit accumulations especially during the daytime, but
higher passes could receive some short duration travel impacts at
times. For lower elevations, some thunderstorms will produce small
hail/graupel with brief accumulations possible with stronger or
more persistent cells.
For Sunday-next Monday, the medium range guidance begins to
diverge on the track of the upper low although is main effects
will still affect portions of eastern CA-western NV. Another
vorticity wave may rotate around the main low on Monday, so we
will keep a mention of showers and isolated afternoon-evening
thunder going into next week. The overall cold pool will weaken so
we will gradually increase Temperatures and raise snow levels, but
highs will still remain below average. MJD
&&
.AVIATION...
VFR conditions will prevail thru midweek with generally light
winds shifting from north tonight to northeast=east Tuesday, then
becoming west by Wednesday afternoon. Isolated showers over
northwest-west central NV will diminish this evening, but no
precip is expected to affect any of the main terminals.
The absence of additional rain today and northeast flow over the
Sierra will limit significant fog formation around KTRK late
tonight- early Tuesday, although patches of shallower fog (with
limited impacts to aviation) could develop in the more fog prone
portions of the Martis valley. MJD
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$
For more information from the National Weather Service visit...
http://weather.gov/reno
[top]
Area Forecast Discussion
National Weather Service Phoenix AZ
255 PM MST MON MAY 16 2016
.SYNOPSIS...
A large Pacific low pressure system is expected to move south from
Idaho, and into Arizona late Tuesday through Wednesday. Increasing
clouds with a chance of showers and thunderstorms are forecast to
spread from southeast California and southwest Arizona late Tuesday
afternoon, into south central Arizona Tuesday night and Wednesday.
Clearing is expected Wednesday night, with dry weather and near
normal temperatures developing toward the end of the work week and
weekend.
&&
.DISCUSSION...
Tonight through Wednesday Night...
An interesting weather pattern will develop over the region the next
few days. A large former Pacific low pressure system, centered over
southwest Idaho since Sunday, will start to move south toward AZ.
Strong ridge building along the Pacific northwest coast, folding
over into southwest Canada, bodes well for the Idaho trof to
retrograde and track southwest into southern CA Tuesday and Tuesday
night. Mid/hi level cyclonic shear will increase the potential for
showers and thunderstorms, with increasing moisture. The San Diego
sounding showed some appreciable low level moisture, and the
Chihuahua Mexico balloon sounding showed a hint of a significant
moisture plume visible south of the border in precip water satellite
imagery. Lastly, the Phoenix and Tucson Radar VAD Wind Profiles were
already detect backing south to southwest winds under 12 thsd feet.
As the trof deepens from Idaho toward southern CA, low level winds
will continue to back from the south, importing more moisture into
the tight mid/hi level cyclonic circulation feature expected
Tuesday/Tuesday night. In other words, as the trof moves slowly west
to east, a threat of showers and thunderstorms will first develop in
southeast CA/southwest AZ late Tuesday afternoon,then spread into
south central AZ, including Phoenix, Tuesday night and Wednesday.
Clearing is expected Wednesday night.
Thursday and Friday...
In the aftermath of Wednesdays eastward moving trof, dry west to
northwesterly flow will develop Thursday over our forecast area.
The flow aloft will change to dry southwesterly in advance of yet
another large Pacific weather system expected to develop
However another Large Pacific weather system will settle into the
western states this weekend, producing gusty south to southwest
winds area-wide Fri, Sat, Sun, and Mon afternoons.
&&
.AVIATION...
South-Central Arizona including KPHX...KIWA and KSDL...
No aviation weather impacts expected through Tuesday afternoon.
Southeasterly flow will veer to westerly this afternoon, peaking
around 10 kt with occasional gusts to around 15 kt. Onset of
the downslope easterly flow will occur near the climatological
average of 09-10z.
Southeast California/Southwest Arizona including KIPL and KBLH...
Typical diurnal winds expected at the terminals, generally less than
15 kt at KIPL and KBLH. Looking ahead, scattered showers and
thunderstorms will likely develop ahead of an approaching low
pressure system Tuesday afternoon. The strongest storms will be
capable of producing strong downdraft winds.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Wednesday through Sunday...
An upper level low will begin weakening on Wednesday with just a
slight chance of showers and thunderstorms east of the Lower
Colorado River Valley. Temperatures will be below normal over south-
central AZ and at or slightly above normal across southeast
California and southwest Arizona. The system exits on Thursday for
warmer temperatures and increasing winds. Another system slowly
approaches from the northwest Friday into Sunday for breezy to windy
conditions each day and a cooling trend. Minimum humidities will
generally be in the 15-20 percent range over the lower deserts
through Thursday before declining to near 10 percent by Friday.
Friday afternoon, and possibly Saturday afternoon, will likely have
elevated fire danger conditions over portions of the area.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Vasquez
AVIATION...Hirsch
FIRE WEATHER...Kuhlman
[top]
Area Forecast Discussion
National Weather Service San Francisco Bay Area
151 PM PDT MON MAY 16 2016
.SYNOPSIS...Warming trend will likely peak on Tuesday as light
offshore winds persist in the hills as high pressure builds.
Onshore winds return to the coast Wednesday with coastal cooling
while inland areas remain warm. More significant cooling trend
starts Thursday as westerly winds develop ahead of incoming
trough. Well below normal daytime highs Friday through Sunday with
a chance of showers...especially in the North Bay on Saturday.
&&
.DISCUSSION...as of 1:51 PM PDT Monday...Northerly gradient down
the coast in excess of 5 mb with large scale SFO-WMC gradient now
neutral. This is all setting the stage for some offshore winds in
the hills and boundary layer later tonight into Tuesday morning.
Already this afternoon starting to see some evidence of upcoming
warming trend with places like Concord and Santa Rosa already into
the 80s as of 1 pm. Developing offshore flow and warming aloft
will lead to pronounced warming on Tuesday with inland highs well
into the 80s and lower 90s. Given the time of year and short
duration of the event the beaches of Monterey county may miss out
on the warm weather but will only have to go a few miles inland to
find 80s on Tuesday.
The airmass aloft will actually warm Tuesday into Weds with 850 mb
temps warming from 15 Celsius to around 18 Celsius...however the
offshore component will be lost as winds are projected to be off
the ocean for most of Weds. Some hill and inland areas may see
little overall change from Tuesday to Weds but the general idea
will be for cooling near the bays on Weds as onshore winds return
through the afternoon.
Thursday will mark the beginning of a noted cooling trend that
will last right through the weekend and likely into early next
week. For Thursday winds will become strong over the ocean with
gusty onshore winds Thursday afternoon ahead of an unseasonably
deep and cold upper trough. If current model solutions are correct
Thursday evening will be blustery at the coast with dramatic 500
mb height falls and strong cold advection off the ocean.
Sweatshirt sales will be strong in the city on Friday with
unseasonably cold upper trough over the region...in fact
temperatures will become fairly isothermal across the region with
little variation in temperature from the coast to the inland
valleys. 850 mb temps from 2-3 Celsius on Friday and Saturday per
the latest ECMWF with the core of the cold air aloft staying over
the North Bay. In general have raised pops over the North Bay and
dragged precip chances down into the Bay Area and towards Santa
Cruz on Saturday. MOS guidance shows pops as high as 50% but since
were still 5 days out have kept official forecast in the 20-30%
range. Should pattern verify t-storms will become possible with
500 mb temps from -23 to -25 Celsius over the North Bay and 700 mb
around -7 Celsius (snow in the Sierra). Given its still days out
and exact track of upper low will likely change didn`t want to
paint t-storms into forecast with bigger impacts likely being
below normal temps and showers. For reference the ECMWF has a
general 0.25-0.50 of liquid for northern Sonoma County this
weekend with a tenth or less for the greater Bay Area.
Low should eject by Sunday with shower chances decreasing but
temps still below normal...mainly in the 60s.
By May standards the pattern remains active and unseasonably cool
with long range models keeping a trough over the West Coast. No
big storms of note but above average confidence for below normal
temps through most of next week.
&&
.AVIATION...as of 11:23 AM PDT Monday...VFR conds now prevail at
all area terminals with marine stratus having retreated southward
and offshore aside from some lingering patches along the southern
San Mateo County coast and around Monterey Bay and the northern
Big Sur coast.
Onshore winds are expected to pick up significantly this afternoon...
with latest HRRR model output increasing the SFO-SAC sea level
pressure gradient to nearly 4 mb by the latter part of the
afternoon.
Tonight...Coastal stratus is projected to redevelop during the
evening hours and begin extending back inland through the Bays. As
the night progresses however...surface high pressure will
increasingly build inland through the Pacific Northwest and into
the northern Great Basin. This will turn surface flow more offshore
especially over the northern half of the district eroding the
marine layer and marine air influence.
Consistent with latest model output and guidance latest TAFs have
cig onset at KSFO and KOAK during the late evening hours...but
then with early clearing on Tuesday as drier air mass works in.
Vicinity of KSFO...VFR cigs through the afternoon and early
evening hours...with moderate confidence will continue VFR through
the evening rush. Winds increasing out of the west during the
afternoon...to 20 to 25 kt with gusts 25 to 30 kt late
afternoon/early evening hours. Low-to-moderate confidence in
timing and details of cig development overnight.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR conds now prevail...and are expected
to continue through the afternoon hours. High confidence that cigs
will redevelop during the evening hours but lower confidence in
details of timing.
&&
.MARINE...as of 1:21 PM PDT Monday...Strong high pressure over
the Eastern Pacific and lower pressure over the interior will
result in gusty northwest winds through much of the week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...Mry Bay until 11 PM
SCA...Pigeon Pt to Pt Pinos 0-10 nm until 11 PM
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pt Reyes to Pigeon Pt 0-10 nm
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
SCA...Rough Bar Advisory for SF Bar
SCA...SF Bay until 9 PM
&&
$$
PUBLIC FORECAST: RWW
AVIATION: Blier
MARINE: Blier
Visit us at www.weather.gov/sanfrancisco
Follow us on Facebook and twitter at:
www.Facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
1102 PM PDT SAT MAY 14 2016
.SYNOPSIS...
Breezy winds and near normal temperatures... with a chance of
precipitation through Monday and possibly lingering in the
mountains Tuesday afternoon. Offshore flow will make Wednesday and
Thursday the hottest days of the week. By Friday there will be an
increase in clouds and a cooling trend for the weekend.
&&
.UPDATE...
A cool day today with most coast and vlys temps coming in 4 to 8
degrees below normal. The marine layer is about 1800 feet and is
capped by a moderate inversion. The major player today is the
onshore flow which is an impressive 9.3 mb onshore to KDAG at 00Z
with this strong an east push there was very slow to no clearing
across the LA and VTA beaches. A little weak trof mixed the marine
layer out across the central coast and it will be slower to
reform. There will be plenty of low clouds over the VTA and LA
coasts and vlys but the SBA south coast will stay predominately
cloud free as the sun downer will keep the low clouds at bay.
The wind advisories for the Antelope Valley and the SBA south
coast are not too well but the SBA winds will likely pick up in
a few hours and there will be some local advisory level winds in
the AV but the stronger winds will be tomorrow.
Overall the current fcst is in good shape and there are no updates
planned.
&&
.SHORT TERM...(TDY-MON)
Upper level low currently moving eastward into Oregon and by
Sunday is centered over the Oregon/Idaho border. Around that time
it really becomes a split flow situation to stop its eastward
progression and the low begins to dig southward into Nevada over
the short term forecast. Models generally agree in placing the
center somewhere near Vegas on Tuesday. This trough pattern over
the west coast will result in little day to day changes through
the short term. Expect only minor fluctuations in the depth of the
marine layer and the extent of overnight/morning stratus. Onshore
pressure gradients will be strong enough to slow the pace of
afternoon clearing, with some immediate coastal areas staying in
the stratus through the afternoon. Northwest flow should help keep
the SBA coast clear at night. Had a few reports of drizzle in
Ventura County and overnight drizzle possibilities will continue
each night. Both the GFS and NAM swing a weak area of lift through
the area late tonight and tomorrow morning as the tail end of a
vort lobe around the upper low swings through. This may enhance
the chance of drizzle for tonight mainly over the LA County coast
and valleys. Decided to pull back on the slight chance of showers
in Los Angeles County coast and San Gabriel Valley for Sunday
afternoon/evening, keeping it instead limited to areas higher up
in the foothills.
High temperatures cool some on Sunday but in general will feel
the same. Models warm low levels a bit on Monday to bring a few
degrees warming mainly inland areas and a few degrees again on
Tuesday. Some far inland areas should even be back up above normal
for this time of year.
Winds will be an issue for the Antelope Valley and the Santa
Barbara south coast and adjacent foothills. Winds have been fairly
tame in the Antelope Valley so far but are expected to pick up
later this evening and stay elevated through Sunday night. For
winds in SBA County, gusty northwest winds will develop this
evening and again Sunday evening. Local numerical model indicates
stronger winds for Sunday evening. Another wind advisory will
likely be needed again for the same areas on Sunday night.
Have introduced a slight chance of showers over the eastern San
Gabriels for Tuesday afternoon/evening. With the position of the
closed upper low forecast to be near Vegas Tuesday, there could
be just enough instability and dynamics to produce some showers.
GFS and NAM both showing an area of negative lifted indicies along
with some CAPE. Moisture availability will be an issue however.
.LONG TERM...(TUE-FRI)
The closed upper low just to our NE is forecast to fill, open up,
and move east on Wednesday. Just enough in the way of height rises
to squeeze a few more degrees of warming Wednesday following
another night of coastal stratus (northwest flow should keep the
SBA south coast clear). Expecting above normal temperatures for
all but the immediate coast which will remain at or just below
normal.
By Thursday the next closed upper low forecast to dive down the
west coast will begin to increase our onshore pressure gradients,
thicken up the marine layer and stratus coverage, and start a
cooling trend that continues into Friday. The cooling will occur
first over inland areas Thursday then spread across the forecast
area Friday. Expect Saturday to be much the same as Friday as far
as marine layer and high temperatures. Some differences in the
east-west position of the low by 12z Saturday with the GFS along
the Oregon coast and the ECMWF further east over OR/ID border. But
this difference won`t impact the forecast for this long term
period.
&&
.AVIATION...15/06Z...
At 05z at KLAX... the inversion was about 1500 feet deep. The top
of the inversion was near 5150 feet with a temperature of thirteen
degrees Celsius.
Overall... Moderate confidence in the 06z TAFs. The reduced
confidence is primarily due to the uncertain timing of the low
cloud incursion and a bit due to uncertainty in the locations that
will be impacted. Most coastal and adjacent valley locations will
be impacted but there is up to a twenty percent chance that some
locations will remain VFR. Some wind shear in the KSBA vicinity
through 09z. Otherwise and elsewhere VFR conditions will prevail.
KLAX... Moderate confidence in the 06z TAF. The reduced
confidence is primarily due to the possibility of the height of
the marine layer fluctuating overnight. There is a 20 percent
chance of an east wind component 8-9 knots from 10Z-15z. There is
a thirty percent chance of no clearing Sunday afternoon.
Otherwise VFR conditions will prevail.
KBUR... Moderate confidence in the 06z TAF. The reduced
confidence is primarily due to the possibility of the height of
the marine layer fluctuating overnight. There is a twenty five
percent chance of the clearing delayed until 19z. Otherwise VFR
conditions will prevail.
&&
.MARINE...14/200 pM.
Northwest winds will continue to create small craft advisory
conditions from Piedras Blancas to San Nicolas island including
the west portion of the Santa Barbara basin through Monday night.
The strongest winds will likely occur in the vicinity of the
Northern Channel islands this afternoon. The Northwest winds will
increase to possible gale force from Piedras Blancas to San
Nicolas island Sunday afternoon and prevail through Monday
morning. Northwest winds are expected to increase Thursday from
Piedras Blancas to San Nicolas island and sca conditions are
likely.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 3 AM PDT Sunday For zones
39-52. (See LAXNPWLOX).
Wind Advisory in effect until 9 PM PDT Sunday For zone 59. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 PM PDT Sunday For
zones 645-670-673-676. (See LAXMWWLOX).
Gale Warning in effect from 3 PM Sunday to 4 AM PDT Monday
For zones 645-670-673-676. (See LAXMWWLOX).
Small Craft Advisory in effect until 3 AM PDT Sunday For zone
650. (See LAXMWWLOX).
&&
$$
PUBLIC...Rorke
AVIATION...KJ
MARINE...Rorke
SYNOPSIS...Munroe
weather.gov/losangeles
Area Forecast Discussion
National Weather Service Sacramento CA
1017 PM PDT SAT MAY 14 2016
.Synopsis...
Cool down with a few showers or thunderstorms north of I-80 this
weekend. Then a warmup to lower 90s again by mid week followed by
another cool down and potential showers late in the week.
&&
.Discussion (Sunday through Tuesday)...
Upper low/trough tracking into/across ORE will be east of the CWA
on Sunday. Northerly winds begin to dry the boundary layer out a
bit on Sunday with stronger drying winds Monday into Tuesday.
Both Sun nite/Mon morning and Mon nite/Tue morning look to be
ideal set-ups for the formation of a modest northerly barrier jet
on the west side of the Sac Valley. Max temps mostly in the 80s
in the Valley on Mon or up to 5 degrees above normal will warm
into the low 90s in the Valley on Tue or 7-12 degrees above
normal. JClapp
&&
.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)
The extended forecast models depict an upper level shortwave
ridge of high pressure over the western portion of the CONUS
Wednesday and Wednesday night, which will bring warm and dry
conditions across NorCal. High temperatures in the valley will be
about 10 degrees above normal Wednesday afternoon.
The stable air over the region on Wednesday will shift southeastward
as another trough of low pressure slides southward from the Pacific
Northwest. Model forecasts are in good agreement to the strength
and positioning of the system to move into NorCal sometime
Thursday afternoon or evening. The disturbance will bring cooler
temperatures and the possibility for showers and thunderstorms
through the end of the workweek. High temperatures in the valley
will drop to near or slightly below normal temperatures in the low
to mid 70s.
&&
.AVIATION...
Mainly VFR conditions the next 24 hours. Isolated showers will
diminish tonight over the Sierra, but are likely to redevelop
Sunday afternoon. South to west winds up to 10 kt will become
northwest on Sunday.
Dang
&&
.STO Watches/Warnings/Advisories...
None.
&&
$$
Area Forecast Discussion
National Weather Service Phoenix AZ
935 PM MST SAT MAY 14 2016
.SYNOPSIS...
Cooler air is beginning to move into the region as a low pressure
system in the northwest U.S. begins to deepen. Breezy conditions are
expected again for Sunday. Another Pacific weather system is
forecast to move into the southwestern states late Sunday through
Tuesday. This will provide even cooler temperatures along with slight
chances of thunderstorms mainly over northern and central Arizona.
Clearing skies with rebounding afternoon temperatures are forecast
for late next week.
&&
.DISCUSSION...
Clearing skies can be seen across southeastern California and the
western half of Arizona this evening. Earlier, a few thunderstorms
swept over the southeastern third of Arizona but that activity has
dissipated and pushed to the east. Low pressure system now over
Oregon continues to gradually deepen and spread its influence further
to the south. Models indicate this system will eventually drop down
towards the south, ultimately moving into northwest Arizona by
Tuesday evening. This will bring a slight chance for thunderstorms to
the region and keep relatively cooler air in place for a few days.
Rain chances are still on the low side but at least there`s a chance
for unsettled weather, particularly Tuesday afternoon through
Wednesday morning. Temperatures should start to climb back above
normals the rest of the week.
&&
.PREVIOUS DISCUSSION...
Latest satellite imagery shows several areas of cumulus congestus,
mainly concentrated across the Mogollon Rim, the CO Plateau and
portions of southeastern AZ. Isolated showers and thunderstorms have
developed, but are mainly relegated to the higher terrain near
Tucson and Flagstaff. Meanwhile, moisture values are running well
above average with dewpoints in the mid 40s. NAEFS PWAT percentiles
are also running above the 90th percentile, though ground based GPS-
IPW and TPW suggest PWATS are somewhat lower. The relatively moist
conditions have also kept temperatures at bay, which have generally
been running in the mid to upper 90s in the lower deserts. At Sky
Harbor Airport, the high has reached 100 degrees.
Preponderance of hi-res CAMs including the operational and
experimental HRRR continue to indicate that isolated convection will develop
across Gila County this afternoon and this evening. PoPs were increased
to around 10 percent in these areas, though in reality most precipitation
that falls will likely evaporate and not measure at the surface. Models
are in excellent agreement that much drier air will be transported
northeastward this evening and overnight, with the GEFS ensemble
mean indicating PWATS dropping as low as 0.40 inches. Consequently,
showers and thunderstorms will dissipate shortly after sunset.
&&
.AVIATION...
South-Central Arizona including KPHX...KIWA and KSDL...
Southeast California/Southwest Arizona including KIPL and KBLH...
A weak weather disturbance will continue to produce scattered
cumulus and altocumulus with broken-overcast cirrus this afternoon
before thinning out this evening. Over northern and southeastern
Arizona there will be isolated thunderstorms with some additional
weaker showers which will begin dissipating after sunset. Surface
winds will favor south and southwest directions through the evening
(gusts of 15-20 kts Phoenix area; 20-30 kts SE CA and SW AZ). Winds
will be stronger Sunday afternoon but with significantly less
cloudiness.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Tuesday through Saturday...
A low pressure system will be centered over northwest Arizona on
Tuesday and Wednesday leading to a slight chance of thunderstorms
over south-central Arizona. Temperatures will be below normal with
light winds. The low exits Thursday before another system approaches
Friday and Saturday leading to breezy to windy conditions.
Temperatures will start off below normal Tuesday and Wednesday before
climbing back to normal by Friday. Humidities begin declining
Wednesday with Minimum values dipping to about 10% late in the week.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Waters/Hirsch
PREVIOUS DISCUSSION...Kuhlman
AVIATION...AJ
FIRE WEATHER...AJ
Area Forecast Discussion
National Weather Service Denver/Boulder CO
830 PM MDT MON MAY 16 2016
.UPDATE...
Issued at 830 PM MDT Mon May 16 2016
Radar shows widespread showers across the plains and Front Range.
Current snow level ranged from around 7000-7500 feet in the
southern foothills, to down as low as 6000 feet near the Wyoming
border as Cheyenne Wyoming had switched over to snow in the last
couple hours. Main precipitation shield is just east of I-25 but
lots of drizzle farther west, with another batch of heavier precip
and snowfall in the mountains around Summit and Park counties. The
main precip area on the plains is shifting slightly westward as
another surge was noted in Northeast Colorado, so rain will
continue through the rest of this evening and then maybe only
slowly decrease through the rest of the night as upslope component
weakens. Even then, drizzle and areas of fog should remain behind
and continue into Tuesday morning with the very moist and ever so
slight upslope component still in place.
With regard to snow in the mountains, the orographic forcing is
rather weak but still convective enough for a heavy burst of snow
this evening in the Summit and Park county areas. Will keep the
advisories going here, but did cancel the advisory farther
northwest where snow has been slow to develop in zone 31 near the
Rabbit Ears Pass area.
&&
.SHORT TERM...(This afternoon through Tuesday)
Issued at 325 AM MDT Mon May 16 2016
500mb low centered over southwest Idaho at the present time is
forecast to track south-southeastward to over central Utah by 06z
tonight. From there models show the low curving southwestward
over the lower Colorado River valley south of Las Vegas by late
Tuesday afternoon. Near zonal mid-level flow on the south side of
this low continues to feed ample amounts moisture over Colorado.
East of the mountains this flow curves northeastward producing a
wide region of weak to moderate qg ascent. Even as the upper low
tracks south across Utah tonight, models show north central and
northeast Colorado under large scale ascent. Returning to this
afternoon...a shortwave trough/vort lobe rotating around the
southeast quad of the upper trough presently aligning from NW
Colorado to SE Colorado. Models show this feature and the
convection its generating swinging newrd across NE Colorado
between 23z/Mon-06Z/Tue. If it were not for the heavy low cloud
cover and chilly temperatures on the plains, mid-level shear,
instability and lift would be adequate to spawn a few strong if
not severe t-storms. As it stands, the few t-storms that have
managed to form over the Palmer Divide have pretty much collapsed
as they moved into the far less favorable environment on the
plains. One last comment, fog blanketing much of northeast
Colorado and many mountain locales since late last night has shown
little signs of dissipating. Many areas along the Front Range
foothills are still reporting vsbys below 5 miles.
Overnight...height and pressure falls on the west slope of
Colorado will further enhance the moist upslope flow up against
the east face of the Front Range mountains. Models indicate weak
to moderate qg ascent moving over northeast and north central
Colorado with the passing shortwave this evening. Model qpf
amounts on the plains by 12z/Tue in the 0.35 to 0.70 inch range.
QPf for the Front Range mountains and foothills in the 0.50 to
0.95 inch range. Snow level based on wetbulb zero anywhere from
7500 to 8500 ft this evening, then anywhere from 6000 to 7000
feet after midnight. Could see snow totals by morning anywhere
from 5-9 inches on east facing slopes above 9000 feet...and 3-6
inches from 7000 to 9000 feet. It`s possible we could see an inch
or so of very wet snow near the base of the foothills and on the
Palmer Divide. Do not expect to see any snow accumulation in the
Denver metro area except maybe a dusting on lawns in the higher
western and southern suburbs. Lastly, should also continue to
see areas of fog with the moist upslope flow...especially up
against the Front Range.
On Tuesday...as the upper low slowly moves away from Colorado
forcing for ascent decreases and the high plains upslope flow
lessens during the afternoon. Precipitable water changes little,
so another day of low clouds, fog and showery type precipitation.
And, another day of unseasonably cool temperatures, especially
east of the Front Range. Highs on Tuesday only in the 40s...with
20s and 30s in the high country. Additional snow amounts anywhere
from 2 to 6 inches in the mountains and higher Front Range
foothills. Additional rain amounts on the plains anywhere from
0.05 inch in the far northeast to around a quarter inch near the
foothills. Airmass appears to be too cool and stable for t-storms
tomorrow mountains and plains.
Last but not least, the Winter Weather Advisory for mountain
zones 31..33 and 34 will remain in effect until 18z/Tuesday.
Should see snowfall rates decreasing by the afternoon.
.LONG TERM...(Tuesday night through Sunday)
Issued at 325 AM MDT Mon May 16 2016
Cool and cloudy start to the extended with an upper level low
spinning over southern CA. This low will weaken as it travels
eastward becoming an open trough by Wednesday afternoon/evening.
Continuing SW flow will keep a steady stream of moisture over NE
Colorado with cold fronts keeping conditions cooler and therefore
more stable. Fro Tuesday night into Wednesday conditions over the
plains will be cool with cloudy skies and chance of showers that
continue into the evening ours before clearing out overnight. Some
models suggesting the clouds will clear sooner on the far NE
plains allowing for some surface heating and therefore increased
instability. This could lead to isolated thunder on the plains
late Tuesday with heavier showers.
Wednesday temperatures will be cooler than average with highs only
getting into the lower 60s. A weak surface high on the plains will
help to keep precipitation out but conditions will remain cloudy.
In the mountains there is a chance of rain and snow showers at
higher elevations with isolated thunderstorms by the afternoon.
There is a deep closed off low entering the Pacific NW that will
allow ridging over NE Colorado on Thursday. There will be enough
moisture in the mountains however to keep a slight chance of
thunderstorms in the afternoon with rain and snow showers above
10,000 ft. Temperatures will rebound back to seasonal normals on
Thursday with highs in the upper 60s to lower 70s.
Friday and through the weekend starts a dry and warming trend. The
upper level low over the Pacific NW will continue to spin over
that region keeping prolonged ridging and therefore increasing
temps over CO. Look for highs into the 70s on Friday and possibly
lower 80s by Saturday and Sunday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 830 PM MDT Mon May 16 2016
IFR conditions will persist through at least Tuesday morning with
shallow upslope keeping rain showers, drizzle, and fog in place.
As rain decreases later tonight, drizzle and fog is expected to
become more prominent. Visibilities may drop to 1/4 to 1/2sm if
fog over the Front Range airports including KDEN 08Z-15Z. Should
see a slow improvement 15Z-18Z Tuesday with MVFR conditions
expected to develop Tuesday afternoon with some daytime heating
and weakening upslope component.
&&
.BOU Watches/Warnings/Advisories...
Winter Weather Advisory until noon MDT Tuesday for COZ033-034.
&&
$$
UPDATE...Barjenbruch
SHORT TERM...Baker
LONG TERM...Bowen
AVIATION...Barjenbruch
[top]
Area Forecast Discussion
National Weather Service Pueblo CO
551 PM MDT MON MAY 16 2016
.UPDATE...
Issued at 547 PM MDT Mon May 16 2016
Severe threat is done for this evening. Watch has been cancelled
for Las Animas and Baca Counties.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 327 PM MDT Mon May 16 2016
Currently...An upper low pressure system was located over the Great
Basin Mon afternoon, while at the sfc high pressure over the
Dakotas was supplying a low level northeasterly push into
Colorado. This was providing an ample amount of low level moisture
for the forecast area today, while disturbances aloft tapped into
the moisture for storm production. Isolated severe storms have
already occurred along the Colorado/New Mexico state line of SE
Colorado, with numerous showers and isolated storms elsewhere.
Extensive cloud cover has kept temps somewhat cool, 50s to lower
60s, and has throttled the fuel for widespread severe storm
activity.
Tonight and tomorrow...The upper low will gradually sink to the
south, then southwest, over the next 24 hrs, dropping into southern
Nevada and California through the day tomorrow. Numerous showers and
isolated thunderstorms are expected to continue through the evening
hours, then showers will linger through the night. Tomorrow the
process will repeat itself, but with the upper low a bit further to
the west and south, convection should diminish over the far eastern
plains while continuing over the western section of the CWA. The
severe threat will also drop south, out of the forecast area. Look
for cool temps tomorrow, with max temps only forecast to climb into
the 50s.
As for ongoing winter wx highlights, significant new accumulations
of wet spring snow for the higher elevations looks reasonable, and
had to issue an advisory for the SW mountains for the continued
threat there until late Tue night. The best window for periods of
heavy rain will likely be this evening through Tue morning, along
the I-25 corridor as well as the lower eastern slopes of the
southern Front Range. Moore
.LONG TERM...(Tuesday night through Monday)
Issued at 327 PM MDT Mon May 16 2016
Upper low settles into AZ Tue night, keeping strong upward
motion over the San Juan and La Garita mountains through the night.
Snow level will likely hang out around 10k-11k with several inches
of accumulation over the peaks. Will keep winter wx advisory in
place through the night, though impact may be limited somewhat by
warm road/ground temps staying near freezing. Tough to rule out
some lighter rain and snow showers across the remainder of the
region, best chances generally over the mountains and interior
valleys, least chance over the plains. Low turns to the corner and
heads east through AZ Wed, keeping precip going over the higher
terrain and most valleys through the day. Kept the advisory going
for now, though snow level will likely rise to above pass level by
afternoon as 700 mb temps begin to climb. Shallow upslope will keep
plains generally cloudy with a few showers possible, though
air mass east of the mountains looks too cool/stable for tsra. On
Thu, upper low weakens as it lifts northeastward across nrn NM and
srn CO. Expect precip Thu/Thu night to be fairly convective in
nature as low levels warm and destabilize somewhat, and will have a
mention of afternoon and evening tsra all areas in the afternoon and
early evening.
Upper ridge then migrates eastward through the state Fri/Sat which
should suppress convection somewhat, though residual moisture will
likely produce some mountain storms both days. Will need to watch
for some dryline storms Sat evening as deeper moisture pushes
north, with boundary along/near the KS border after 00z. Similar
set-up for Sun as Pacific NW upper trough pushes eastward, with
dryline lurking over the far sern plains and potential for high
based tsra over the mountains. Should see max temps Fri-Sat climb
back to above average readings, with 80s reappearing over portions
of the plains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 516 PM MDT Mon May 16 2016
Extended periods of mvfr to lifr are expected for the TAF sites
over the next couple of days, as a low pressure system slowly
moves through the region.
At KALS...expect periods of mvfr...and brief periods of ifr,
as rounds of showers and isold ts move through the valley through
tomorrow. Freezing levels should remain about 1000-1500 ft AGL on
tuesday.
KPUB and KCOS...TS should weaken early this eve, but numerous
showers will continue for the evening. Areas of fog likely to
develop by early morning, especially vicinity KCOS, and cigs
likely to remain IFR through the morning...possibly improving to
MVFR by afternoon. Freezing levels will be about 1000 ft AGL by
early Tue. ROSE
&&
.PUB Watches/Warnings/Advisories...
Winter Weather Advisory from noon Tuesday to midnight MDT
Wednesday night for COZ066-068.
Winter Weather Advisory until 6 AM MDT Tuesday for COZ058-060.
Winter Weather Advisory until noon MDT Tuesday for COZ081.
Winter Storm Warning until 6 AM MDT Wednesday for COZ082.
&&
$$
UPDATE...LW
SHORT TERM...MOORE
LONG TERM...PETERSEN
AVIATION...ROSE
[top]
Area Forecast Discussion
National Weather Service Grand Junction CO
508 PM MDT MON MAY 16 2016
.SHORT TERM...(This evening through Tuesday night)
Issued at 359 PM MDT Mon May 16 2016
Wet, dreary weather continues through the short term as an upper
level low spinning over northern Nevada moves south into the Great
Basin. However, this low will not track through the forecast area.
Rather, it will drop further south into Arizona. Regardless of its
track, ample moisture rotating with this storm will be pulled
into the region over the next couple of days. As a result, expect
a continuation of widespread showers and chance for storms plus
below normal temperatures in the forecast. Guidance temperatures
came in too warm so decided to bump temperatures down a few
degrees to reflect current trends. As with previous model runs,
best chance of precipitation is expected to be during the
afternoon and evening hours so grids continue to reflect that.
Seeing as how the gradient is not too impressive with this storm,
and that the jet core stays well south of the area, do not expect
any significant winds for the region apart from the occasional
gusty outflow wind with storms.
Most impressive QPF remains over the eastern Uinta mountains
and right along the northern divide tonight, but upper level
temps remain quite mild so not expecting any significant
snowfall. Tomorrow night will see the best chance for significant
snowfall especially down south. Orographics remain favorable for
upslope with winds generally remaining out of the southeast
through the overnight hours. However, after examining wet bulb
zero heights and upper level temperatures, do not think there
will be any major impacts for our mountain areas. Storm total
snowfall from tomorrow through Wednesday morning show the San
Juans receiving 4 to 8 inches. Seeing as how this will be over
several periods and the expectation that warm road surfaces will
melt any falling snow, chose to not issue any advisories at this
time. Will continue to monitor the situation and let future
shifts decide if highlights should be issued.
.LONG TERM...(Wednesday through Monday)
Issued at 359 PM MDT Mon May 16 2016
Wednesday will bring another day of widespread showers to the
region. The last pull of wraparound moisture from the departing
trough will keep decent shower coverage going through Thursday
morning before activity shifts to the higher terrain during the
afternoon. A "break" of sorts will finally arrive Friday as a
weak transitory ridge builds ahead of the next storm. However,
cannot rule out an afternoon shower or two during the afternoon
hours. As for the next storm, after remaining stationary off the
coast of the Pacific northwest for several days, it will finally
move onshore beginning Friday. Models indicate this massive low
pressure system will split with the lower portion following the
typical spring-time track. It is projected to drop down into the
Great Basin as early as Sunday night and bring yet another chance
for clouds and showers.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 506 PM MDT Mon May 16 2016
Stormy weather will continue tonight and tuesday as low pressure
remains over the area. Expect widespread showers and scattered
thunderstorms through the period with areas of IFR cigs possible,
and local ifr vsbys. mts will be obscured. Terminal sites may see
periods of ILS cigs as showers move through with brief mvfr and
ifr conditions. Gusty outflow winds to 40 mph and small hail will
accompany the strongest storms and snow levels will be running
between 9 and 10k today, falling to as low as 8k tonight.
&&
.HYDROLOGY...
Issued at 918 AM MDT Mon May 16 2016
With the forecast wet weather and expected warming temperatures
toward the end of the week, river levels are expected to
gradually rise over the next few weeks. Flows will generally
increase due to snowpack melting with some streams reaching near
bankfull at times. Use caution in and near swift currents.
&&
.GJT Watches/Warnings/Advisories...
CO...None.
UT...None.
&&
$$
SHORT TERM...MMS
LONG TERM...MMS
AVIATION...CC
HYDROLOGY...JAM
Area Forecast Discussion
National Weather Service Pueblo CO
141 PM MDT MON MAY 16 2016
.UPDATE...
Issued at 140 PM MDT Mon May 16 2016
Quick update for issuance of the Severe Thunderstorm Watch for Las
Animas and Baca counties until 03z tonight. Incorporated latest
obs and satellite data. Moore
&&
.SHORT TERM...(Today and tonight)
Issued at 450 AM MDT Mon May 16 2016
Multiple meteorological concerns over the forecast district during
the short term, including but not limited to locally heavy rainfall
potential, severe potential, higher elevation snow, areas of low
clouds/fog and temperatures, etc.
Forecast district currently graced by generally above seasonal mid-
May early morning temperatures, variable cloudiness in combination
with areas of low clouds and fog and isolated shower activity.
Latest forecast model soundings, real/near time data, computer
simulations and PV analysis indicate that upper disturbances will
combine with adequate atmospheric moisture and a moist northeasterly
surface surge to allow for the development of generally scattered to
numerous showers and isolated to scattered thunderstorms, once again
favoring the afternoon into the evening/night hours.
Some of these thunderstorms are expected to generate locally heavy
rainfall and also be capable of entering the strong to to severe
category as projected maximum localized capes, LI`s and 0-6 km
shears challenge/exceed 1600 J/Kg, -7C and 45 knots at times
respectively, especially over south-central and southeastern
sections of the forecast district.
At this time, the potential for stronger to severe storms favor
south-central and southeastern locations of the forecast district,
especially from this afternoon into this evening and have mentioned
severe potential(including the potential for large hail, damaging
winds and even an isolated tornado) in upcoming grids/zones over
eastern Las Animas and Baca continues to account for this
potential(although highest potential of organized severe storms
seems to favor locations such as portions of the Texas and Oklahoma
panhandles).
In addition, have also depicted locally heavy rain potential over
eastern portions of the forecast district, including the Interstate
25 corridor and associated burn scars, including but not limited to
the Waldo Canyon burn scar, etc. As always, WFO Pueblo will closely
monitor severe weather and flooding potential closely and issue
necessary highlights/advisories/warnings, etc. as needed.
Also, will maintain winter weather highlights from noon today into
at least Tuesday for Pikes Peak, Teller county and the Rampart Range
as well as for the eastern Sawatch Mountains and the Western
Mosquito Range, where significant late season is anticipated over
these locations during this time-frame.
Will also depict areas of fog and low clouds over several locations
at times during the near/short term in combination with continued
below seasonal mid-May maximum temperatures and near to above
seasonal minimum temperatures over the majority of the CWFA during
the next 24 hours.
.LONG TERM...(Tuesday through Sunday)
Issued at 450 AM MDT Mon May 16 2016
On Tue a large upr level low wl be centered ovr UT, with plenty of
mstr ovr the forecast area. The weather wl remain unsettled with
widespread pcpn chances over the mtns and high valleys. Over the
sern plains upslope flow continues and chances for light showers
look good...but closer to the mtns there may be better chances for
pcpn and accumulations. It looks like the swrn mtns wl be hardest
hit with snow on Tue...although the rest of the mtns wl also see
accumulations. Tue wl be the coolest day with highs in the mid 40s
to lower 50s at the lower elevations.
Tue night the upr low centered is expected to move south into AZ.
Snow is expected to continue ovr the mtns, with the best
accumulations still expected to be ovr the swrn mtns. the lower
elevations may see some light pcpn thru the night.
On Wed the upr low is expected to weaken and become an open wave and
being moving eastward acrs NM and CO. The mtns, high valleys and
I-25 corridor wl continue to see good chances for pcpn, while the
sern plains may just see some isold pcpn. Highs on Wed are expected
to be a little warmer, but wl still be below average with highs only
in the 50s at the lower elevations.
Wed night the upr trof is expected to move ovr far ern CO and pcpn
chances are expected to decrease ovr much of the area. On Thu there
wl still be enough moisture ovr the area that we should again sct or
high chances for pcpn ovr the mtns and high valleys, with isold pops
ovr the plains. temps should be a little warmer Thu but still below
average.
Finally, on Fri it looks drier ovr the area as a upr ridging
develops ovr ern co ahead of an upr low ovr OR and nrn CA. The
ridge shifts eastward ovr KS on Sat, with increasing southwest flow
ovr the forecast area. Chances for pcpn look mostly confined to the
mtn areas on Fri and Sat, but we may also see some isold
showers/tstms move out ovr the ern plains Sat afternoon and evening.
High temps Fri and Sat are expected to be above average. On Sun the
upr trof is forecast to move ovr NV which wl keep south to southwest
flow aloft ovr the forecast area and mainly dry conditions. However
there may still be some isold showers/tstms ovr the mtns and the dry
line may be near the KS border Sun afternoon.&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 450 AM MDT Mon May 16 2016
MVFR to localized IFR/LIFR ceilings and visibilities at times will
be possible over the KCOS and KPUB taf sites this morning due to
areas of low clouds and fog. Similar to the previous 24 hours,
periods of MVFR/IFR and LIFR conditions due to shower and
thunderstorm activity will be possible at times over the KALS, KCOS
and KPUB taf sites into tonight. In addition, the potential for
strong to severe thunderstorms exist primarily over south-central
and southeastern Colorado from late this morning into this evening,
although the potential does exist that stronger storms capable of
producing locally heavy rainfall, hail and gusty winds may be noted
in the vicinity of the KALS, KCOS, and KPUB taf sites respectively
from later today into this evening
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 450 AM MDT Mon May 16 2016
MVFR to localized IFR/LIFR ceilings and visibilities at times will
be possible over the KCOS and KPUB taf sites this morning due to
areas of low clouds and fog. Similar to the previous 24 hours,
periods of MVFR/IFR and LIFR conditions due to shower and
thunderstorm activity will be possible at times over the KALS, KCOS
and KPUB taf sites into tonight. In addition, the potential for
strong to severe thunderstorms exist primarily over south-central
and southeastern Colorado from late this morning into this evening,
although the potential does exist that stronger storms capable of
producing locally heavy rainfall, hail and gusty winds may be noted
in the vicinity of the KALS, KCOS, and KPUB taf sites respectively
from later today into this evening
&&
.PUB Watches/Warnings/Advisories...
Winter Weather Advisory from noon Tuesday to 6 AM MDT Wednesday
for COZ066-068.
Winter Weather Advisory until 6 AM MDT Tuesday for COZ058-060.
Winter Weather Advisory from 6 PM this evening to noon MDT
Tuesday for COZ081.
Winter Storm Warning until 6 AM MDT Wednesday for COZ082.
&&
$$
UPDATE...MOORE
SHORT TERM...77
LONG TERM...28
AVIATION...MOORE
Area Forecast Discussion
National Weather Service Denver/Boulder CO
1222 PM MDT MON MAY 16 2016
.UPDATE...
Issued at 1215 PM MDT Mon May 16 2016
convection now underway over the Front Range and western sections
of the Palmer Divide in Douglas County. Weather spotter just
reported small hail falling from a single t-storm south-southeast
of Castle Rock. Precipitation will continue to expand especially
over and east of the Front Range as upslope flow deepens and qg
ascent increases ahead of a vort lobe/shortwave trough rotating
up from southern Colorado. On another note, fog continues to
plague many areas with visibilities less than 2 miles in portions
of the I-25 corridor. Fog may be slow to dissipate today. Will
adjust afternoon forecast grids accordingly.
UPDATE Issued at 915 AM MDT Mon May 16 2016
Fog persists at this hour across most of the greater Denver metro
area...although web cams and surface obs reveal a significant
improvement in visibilities in areas roughly south of Interstate
70 and east of Aurora. The thickest fog was over northwest
sections of the metro area such as around Boulder and Broomfield
where prevailing vsbys were still below 1/4 mile. Should see this
heavy fog erode from southeast-to-northwest over the next hour or
two as slightly drier air flows down off the Palmer Divide and
with mixing of the boundary layer with passing rain showers. Vort
lobe/shortwave trough rotating northward over the CWA during the
next couple of hours will enhance this shower activity as noted
in the previous discussion. Isolated t-storms also a possibility
towards midday. Hail, brief heavy rain and perhaps a funnel cloud
or two all possible with these cells. At this time, will make
only minor adjustments to the ongoing forecast. Will also hang
onto the winter weather and dense fog highlights for now.
&&
.SHORT TERM...(Today and tonight)
Issued at 402 AM MDT Mon May 16 2016
Pockets of dense fog have formed in the Denver and Boulder areas
with visibilities less than a quarter mile at times. Partial
clearing after last evening`s period of rain allowed for strong
radiational cooling along parts of the i-25 urban corridor.
Visibilities at KDEN have been less than a quarter mile since
about 2 AM MDT and a co-worker driving up Davidson Mesa outside of
Boulder reported visibilities less than 100 feet. Other
observations from local airports show visibilities greater than a
mile and a half. Have issued a dense fog advisory for zones 39 and
40 until 10 AM MDT to handle the morning rush hour.
Otherwise, the forecast remains on track. A band of showers has
been moving over western Colorado this morning with some embedded
thunderstorms as late at 3:30 AM MDT. These showers should
progress into the north central mountains in the next few hours
and then over northeast Colorado later today. The approaching
upper trough will place Colorado under rising motions through this
evening. The airmass is plenty moist and slightly unstable at mid-
levels which will allow for an extended period of precipitation
through this afternoon and evening. Temperatures in the mountains
are expected to cool through today with snow levels eventually
coming down to 10000 feet or lower. Significant accumulations will
be possible on the peaks, ridges and higher elevation roadways, so
a Winter Weather Advisory will be in effect through Tuesday.
Temperatures are going to be much cooler than normal due to the
lack of sunshine and occurring precipitation. Areas of
precipitation are expected to continue into the evening and then
diminish overnight.
.LONG TERM...(Tuesday through Sunday)
Issued at 402 AM MDT Mon May 16 2016
Models have an upper closed low over Nevada into western Colorado
at 12z Tuesday. The upper low weakens and falls apart as it moves
slowly eastward and across the CWA as an open trough through
Wednesday night. The flow aloft will weak all four periods. The
models keep weak qg upward vertical velocity for the CWA into
Wednesday night. Models have easterly low level flow for the CWA
Tuesday, then southeasterly well into Wednesday. Winds should be
close to normal diurnal drainage patterns Wednesday night. Models
show quite a bit of moisture over the CWA well into Wednesday
before decrease overnight. The qpf Fields show measurable
precipitation across all the CWA Tuesday into Tuesday evening.
There is very little measurable precipitation noted Wednesday and
Wednesday evening for the plains, but some in the mountains. There
is some CAPE mainly in the mountains and foothills late day
Tuesday and late day Wednesday. Lapse rates are not very steep,
especially over the plains both late days periods. will go with
30-60% pops on Tuesday and Tuesday evening. Late day Wednesday`s
pops are similar in the mountains and foothills only. The plains
can expected 10-20%s. for temperatures, Tuesday`s highs are 1-3 C
warmer than today`s expected highs. Wednesday`s readings warm up
2-5 c above Tuesday`s readings.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1215 PM MDT Mon May 16 2016
will hang onto ils cigs and vsbys at denver area terminals for
the remainder of the afternoon. may not see vsbys rising above 3
miles all day, even with passing showers and t-storms. ceilings
now not expected to rise above 1000 ft agl all day at KDEN, KAPA
and KBJC.
&&
.BOU Watches/Warnings/Advisories...
Winter Weather Advisory until noon MDT Tuesday for COZ031-033-
034.
&&
$$
UPDATE...Baker
SHORT TERM...Dankers
LONG TERM...RJK
AVIATION...Baker
Area Forecast Discussion
National Weather Service Grand Junction CO
1129 AM MDT MON MAY 16 2016
updated aviation section
.UPDATE...
Issued at 918 AM MDT Mon May 16 2016
Rain/Snow line is at about 8300 feet this morning, but will rise
throughout the day. Snow accumulation level on roads as of 9am
looks to be above 10,000 ft at the high passes, so have refrained
from issuing any advisories today with impacts minimal. Will keep
an eye on precipitation development, but expecting short lived
convective showers and thunderstorms this afternoon. Short term
forecast models indicate downturn in activity after sunset when
snow would accumulate on the roads again. Expecting the best
thunderstorms to develop across the Four Corners today with hail
the main threat.
&&
.SHORT TERM...(Today through Tuesday night)
Issued at 254 AM MDT Mon May 16 2016
Energy rotating around an upper level low located over southern
Idaho will continue to bring showers and thunderstorms to much of
eastern Utah and western Colorado through Tuesday.
First wave working through the area this morning with showers and
thunderstorms driving east into the central mountains. Snow levels
remain above 9k and bulk of activity has been light so far, so no
plans on hoisting any winter highlights for narrow stretches of
our high mountain passes. Could see a few inches accumulate above
10k by this evening, but road surfaces remain warm and impact
should be minimal. Otherwise, it`s looking like another unsettled
day with a few stronger storms again expected as moisture and
additional energy pass through. Wind gusts to 50 mph not out of
the question along with small hail. Models have remained
aggressive with pops and QPF values peaking during the afternoon
and evening hours. See no reason to stray far from that thinking
and pop grids will be geared this direction.
As the low drops or sags south into Utah, colder air will slide
south with it. This will lower snow levels a bit by Tuesday
morning, possibly as low as 8k, but levels rise throughout the day
back to near 10k by afternoon. Overall a very similar weather day
is expected with showers and thunderstorms throughout the region
and some accumulating snowfall for the highest peaks. Best shot at
more significant snowfall will push into the San Juans late
Tuesday and Tuesday night when we see another stronger wave rotate
out of the digging low with a period of favorable orographics and
dynamics coming into play. This will generate more persistent
precipitation that may eventually lead to more significant
snowfall accumulations from Telluride southeast to Wolf Creek
Pass. Main impacts would be overnight Tuesday into Wednesday
morning and later shifts can take a look at the need for any sort
of winter highlights.
Temperatures will be running on the cool side of normal through
mid-week and have undercut guidance values a bit today and again
on Tuesday due to cloud cover and showers.
.LONG TERM...(Wednesday through Sunday)
Issued at 254 AM MDT Mon May 16 2016
The upper level low will slowly fill over the southern Great Basin
by the end of the week with the cool and unsettled weather slowly
abating as we close out the week. The low fills on Wednesday with
remnants getting kicked out by late Thursday. This will lead to a
decrease in the showers and also send in some warmer air aloft
which lifts snow levels back up to near 10k by Wednesday
afternoon. Scattered activity then lingers through Thursday
afternoon, favoring the higher terrain.
By Friday, the Pacific Northwest gets a taste of what we`ve been
experiencing as a deep area of low pressure sets up just off the
coast and gets cutoff. This system barely moves from Thursday
through Sunday. The location of the low will cause a ridge to form
to our east pushing the trough to the plains and keeping us
`relatively` dry. Some afternoon convection can`t be ruled out as
ample moisture will remain while daytime heating will help to
destabilize the atmosphere. After the first half of the week
though, the weather will show a marked improvement.
Temperatures will slowly warming up through the weekend.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1129 AM MDT Mon May 16 2016
Stormy weather continues across the region through the end of the
week. Expect widespread showers and isolated thunderstorms through the
period with areas of IFR cigs possible, especially over the
higher elevations. Terminal sites may see periods of ILS cigs as
showers move through. Gusty outflow winds to 50 mph and small hail
will accompany the strongest storms and snow levels will be
running between 9 and 10k today, falling to as low as 8k tonight.
Mountain obscuration likely over the next 24 hours.
&&
.HYDROLOGY...
Issued at 918 AM MDT Mon May 16 2016
With the forecast wet weather and expected warming temperatures
toward the end of the week, river levels are expected to
gradually rise over the next few weeks. Flows will generally
increase due to snowpack melting with some streams reaching near
bankfull at times. Use caution in and near swift currents.
&&
.GJT Watches/Warnings/Advisories...
CO...None.
UT...None.
&&
$$
UPDATE...JAM
SHORT TERM...JDC
LONG TERM...TGR/JDC
AVIATION...TGJT
HYDROLOGY...JAM
Area Forecast Discussion
National Weather Service Grand Junction CO
918 AM MDT MON MAY 16 2016
.UPDATE...
Issued at 918 AM MDT Mon May 16 2016
Rain/Snow line is at about 8300 feet this morning, but will rise
throughout the day. Snow accumulation level on roads as of 9am
looks to be above 10,000 ft at the high passes, so have refrained
from issuing any advisories today with impacts minimal. Will keep
an eye on precipitation development, but expecting short lived
convective showers and thunderstorms this afternoon. Short term
forecast models indicate downturn in activity after sunset when
snow would accumulate on the roads again. Expecting the best
thunderstorms to develop across the Four Corners today with hail
the main threat.
&&
.SHORT TERM...(Today through Tuesday night)
Issued at 254 AM MDT Mon May 16 2016
Energy rotating around an upper level low located over southern
Idaho will continue to bring showers and thunderstorms to much of
eastern Utah and western Colorado through Tuesday.
First wave working through the area this morning with showers and
thunderstorms driving east into the central mountains. Snow levels
remain above 9k and bulk of activity has been light so far, so no
plans on hoisting any winter highlights for narrow stretches of
our high mountain passes. Could see a few inches accumulate above
10k by this evening, but road surfaces remain warm and impact
should be minimal. Otherwise, it`s looking like another unsettled
day with a few stronger storms again expected as moisture and
additional energy pass through. Wind gusts to 50 mph not out of
the question along with small hail. Models have remained
aggressive with pops and QPF values peaking during the afternoon
and evening hours. See no reason to stray far from that thinking
and pop grids will be geared this direction.
As the low drops or sags south into Utah, colder air will slide
south with it. This will lower snow levels a bit by Tuesday
morning, possibly as low as 8k, but levels rise throughout the day
back to near 10k by afternoon. Overall a very similar weather day
is expected with showers and thunderstorms throughout the region
and some accumulating snowfall for the highest peaks. Best shot at
more significant snowfall will push into the San Juans late
Tuesday and Tuesday night when we see another stronger wave rotate
out of the digging low with a period of favorable orographics and
dynamics coming into play. This will generate more persistent
precipitation that may eventually lead to more significant
snowfall accumulations from Telluride southeast to Wolf Creek
Pass. Main impacts would be overnight Tuesday into Wednesday
morning and later shifts can take a look at the need for any sort
of winter highlights.
Temperatures will be running on the cool side of normal through
mid-week and have undercut guidance values a bit today and again
on Tuesday due to cloud cover and showers.
.LONG TERM...(Wednesday through Sunday)
Issued at 254 AM MDT Mon May 16 2016
The upper level low will slowly fill over the southern Great Basin
by the end of the week with the cool and unsettled weather slowly
abating as we close out the week. The low fills on Wednesday with
remnants getting kicked out by late Thursday. This will lead to a
decrease in the showers and also send in some warmer air aloft
which lifts snow levels back up to near 10k by Wednesday
afternoon. Scattered activity then lingers through Thursday
afternoon, favoring the higher terrain.
By Friday, the Pacific Northwest gets a taste of what we`ve been
experiencing as a deep area of low pressure sets up just off the
coast and gets cutoff. This system barely moves from Thursday
through Sunday. The location of the low will cause a ridge to form
to our east pushing the trough to the plains and keeping us
`relatively` dry. Some afternoon convection can`t be ruled out as
ample moisture will remain while daytime heating will help to
destabilize the atmosphere. After the first half of the week
though, the weather will show a marked improvement.
Temperatures will slowly warming up through the weekend.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 254 AM MDT Mon May 16 2016
Unsettled weather will remain in the region through Tuesday.
Expect widespread showers and isolated thunderstorms through the
period with areas of IFR cigs possible, especially over the
higher elevations. Terminal sites may see periods of ILS cigs as
showers move through. Gusty outflow winds to 50 mph and small hail
will accompany the strongest storms and snow levels will be
running between 9 and 10k today, falling to as low as 8k tonight.
Mountain obscuration likely over the next 24 hours.
&&
.HYDROLOGY...
Issued at 918 AM MDT Mon May 16 2016
With the forecast wet weather and expected warming temperatures
toward the end of the week, river levels are expected to
gradually rise over the next few weeks. Flows will generally
increase due to snowpack melting with some streams reaching near
bankfull at times. Use caution in and near swift currents.
&&
.GJT Watches/Warnings/Advisories...
CO...None.
UT...None.
&&
$$
UPDATE...JAM
SHORT TERM...JDC
LONG TERM...TGR/JDC
AVIATION...JDC
HYDROLOGY...JAM
Area Forecast Discussion
National Weather Service Denver/Boulder CO
821 PM MDT SUN MAY 15 2016
.UPDATE...
Issued at 659 PM MDT Sun May 15 2016
The second band of showers today is now moving off the foothills.
some lightning persisted to near Jefferson County Airport...but
for the most part these showers are again weakening as they move
to the plains. This is part of a large band of clouds that extend
to the west slope...but satellite loops show a large dry slot
moving into southwest Colorado. The HRRR and RAP models both show
a dry period from around 06z to 13z for the metro area.
The surface pattern has been weak this evening...but a surface low
is forecast to develop near trinidad late tonight and intensify
tomorrow morning. This will result in increasing upslope flow
along the urban corridor and palmer divide...with showers
redeveloping Monday morning and continuing through the day.
Coordinated with adjoining offices on winter weather
advisory...and will issue one for the higher mountain passes
for late tonight through noon Tuesday. Models indicate that some
higher elevations may see up to 30 inches of snow by the time the
storm is done with us. It is likely to be a very wet sloppy mess
with daytime highs in the higher passes reaching 32 tomorrow.
All in all the previous forecast has a good handle on system
development...but mav guidance is 5 degrees colder than met
guidance. With the clouds...upslope...and moisture am going to
lower max temps in eastern Colorado on Monday and drop higher
passes a degree or two.
&&
.SHORT TERM...(This evening through Monday)
Issued at 322 PM MDT Sun May 15 2016
Initial shower band moving east on the plains but has mostly
dissipated. A larger batch of showers and thunderstorms over the
mountains will spread onto the plains this evening. This has more
forcing and since it is a large area of rain it will bring higher
dew points with it, so it should survive better. Still expecting a
bit of a break later tonight, but then the low on the east side of
the mountains will start to wind up. Some question about the
amount of low level moisture that persists through the night.
Models seem a bit overdone, so I am showing mostly cloudy skies
but not into the fog/drizzle regime yet, at least around Denver. During
the night the best moisture convergence will be across Wyoming and
the Nebraska panhandle, but this should all slide southward Monday
morning with the lower levels saturating, upslope winds, and
persistent lift. Some uncertainty about the timing of this
progressing from north to south but at this time it looks like
this will be happening during the morning hours. Generally
expecting light but steady rainfall, but with upslope enhancement
over the east slopes of the Front Range. Snow level should also be
lowering a bit during the day, settling somewhere around 7-8
thousand feet on the east slopes with warmer low levels holding it
higher on the west side. Could be some heavy snow in the
afternoon, but warm temps will limit the impact in populated areas
so just the highest roads are of concern.
.LONG TERM...(Monday night through Sunday)
Issued at 322 PM MDT Sun May 15 2016
Monday night...a broad closed upper low will stretch from
Northwest NV into northwest CO. Weak QG ascent will be over the
cwa overnight as this trough makes its way south into AZ by 00z
Wednesday. At the surface...a secondary surge will enhance the
upslope along the Front Range Monday night. The mdls show moderate
to strong QG ascent at the surface through the evening...with the
east to southeast upslope fm the surface to around 600 mb. NAM12
forecast sounding show moist adiabatic lapse rates with the
airmass saturated through the layer. There could be an isolated
tstm in the mountains Monday evening but it looks too stable
across the Urban Corridor and northeast plains with the possible
exception of the Palmer Divide. Overrunning type of setup Monday
night with the colder air below undercutting a fairly strong
inversion just above 700 mb. east and southeast facing aspects
above 9 thousand feet could receive 8 to 12 inches of snowfall by
tuesday morning...but not as much west of the Continental Divide.
No highlights yet but am learning more towards advisory type
snowfall vs warning at this time for the Front Range east of the
Continental Divide and possibly the higher foothills. The
foothills will see a accumulating snowfall above 8 thousand feet
with a steady mix of rain and snow down to 6500 feet. We could
possibly see a mix of rain/snow over the palmer divide above 6
thousand feet by tuesday morning. The mix of rain/snow in the
foothills should help alleviate any potential flooding risk as
well. Tuesday...a deep southeasterly upslope flow will be present
but the wind will not be as strong. Wl keep some light snow or
rain/snow mix in the mountains through the day...with higher pops
for light rain in and near the foothills/Palmer Divide as well. Wl
keep the mention of tstms in the grids but mainly over the
mountains. Tuesday night into Wednesday...the main area of
pcpn continues to get dragged to the south. There is still enough
moisture and some weak forcing around for showers...especially
over the mountain but the overall coverage will be decreasing.
The weakening trough finally shifts to the east of CO by Thu with
a drier and more subsident northwesterly flow aloft. An upper
level ridge will finally set up over the region late Thursday and
continue into Saturday. It will be much warmer by the weekend with
the more typical pattern of aftn/evng thunderstorms on Friday and
Saturday. The mdls continue to show a large upper trough over the
Pacific Northwest by the weekend...with an increasing southwesterly
flow aloft over CO by Sunday.
&&
.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 322 PM MDT Sun May 15 2016
The showers moving through the metro area will be followed by one
or two more bands of rain this evening...but it looks dry from 06z
until at least 13z. The winds have been the big question
today...other than the gusty winds with showers...it has been
difficult to pin down directions. This will become easier tomorrow
with the deepening upslope flow we will settle on north to
northeast winds for much of the day. Ceilings of 030 to 060 with
the showers will rise a bit overnight...then drop to mvfr monday
morning...with areas of ifr.
&&
.BOU Watches/Warnings/Advisories...winter weather advisory for
mountain zones...31...33...34 from 3am tonight to noon Tuesday.
&&
$$
UPDATE...RTG
SHORT TERM...Gimmestad
LONG TERM...Cooper
AVIATION...Gimmestad
Area Forecast Discussion
National Weather Service Denver/Boulder CO
830 PM MDT MON MAY 16 2016
.UPDATE...
Issued at 830 PM MDT Mon May 16 2016
Radar shows widespread showers across the plains and Front Range.
Current snow level ranged from around 7000-7500 feet in the
southern foothills, to down as low as 6000 feet near the Wyoming
border as Cheyenne Wyoming had switched over to snow in the last
couple hours. Main precipitation shield is just east of I-25 but
lots of drizzle farther west, with another batch of heavier precip
and snowfall in the mountains around Summit and Park counties. The
main precip area on the plains is shifting slightly westward as
another surge was noted in Northeast Colorado, so rain will
continue through the rest of this evening and then maybe only
slowly decrease through the rest of the night as upslope component
weakens. Even then, drizzle and areas of fog should remain behind
and continue into Tuesday morning with the very moist and ever so
slight upslope component still in place.
With regard to snow in the mountains, the orographic forcing is
rather weak but still convective enough for a heavy burst of snow
this evening in the Summit and Park county areas. Will keep the
advisories going here, but did cancel the advisory farther
northwest where snow has been slow to develop in zone 31 near the
Rabbit Ears Pass area.
&&
.SHORT TERM...(This afternoon through Tuesday)
Issued at 325 AM MDT Mon May 16 2016
500mb low centered over southwest Idaho at the present time is
forecast to track south-southeastward to over central Utah by 06z
tonight. From there models show the low curving southwestward
over the lower Colorado River valley south of Las Vegas by late
Tuesday afternoon. Near zonal mid-level flow on the south side of
this low continues to feed ample amounts moisture over Colorado.
East of the mountains this flow curves northeastward producing a
wide region of weak to moderate qg ascent. Even as the upper low
tracks south across Utah tonight, models show north central and
northeast Colorado under large scale ascent. Returning to this
afternoon...a shortwave trough/vort lobe rotating around the
southeast quad of the upper trough presently aligning from NW
Colorado to SE Colorado. Models show this feature and the
convection its generating swinging newrd across NE Colorado
between 23z/Mon-06Z/Tue. If it were not for the heavy low cloud
cover and chilly temperatures on the plains, mid-level shear,
instability and lift would be adequate to spawn a few strong if
not severe t-storms. As it stands, the few t-storms that have
managed to form over the Palmer Divide have pretty much collapsed
as they moved into the far less favorable environment on the
plains. One last comment, fog blanketing much of northeast
Colorado and many mountain locales since late last night has shown
little signs of dissipating. Many areas along the Front Range
foothills are still reporting vsbys below 5 miles.
Overnight...height and pressure falls on the west slope of
Colorado will further enhance the moist upslope flow up against
the east face of the Front Range mountains. Models indicate weak
to moderate qg ascent moving over northeast and north central
Colorado with the passing shortwave this evening. Model qpf
amounts on the plains by 12z/Tue in the 0.35 to 0.70 inch range.
QPf for the Front Range mountains and foothills in the 0.50 to
0.95 inch range. Snow level based on wetbulb zero anywhere from
7500 to 8500 ft this evening, then anywhere from 6000 to 7000
feet after midnight. Could see snow totals by morning anywhere
from 5-9 inches on east facing slopes above 9000 feet...and 3-6
inches from 7000 to 9000 feet. It`s possible we could see an inch
or so of very wet snow near the base of the foothills and on the
Palmer Divide. Do not expect to see any snow accumulation in the
Denver metro area except maybe a dusting on lawns in the higher
western and southern suburbs. Lastly, should also continue to
see areas of fog with the moist upslope flow...especially up
against the Front Range.
On Tuesday...as the upper low slowly moves away from Colorado
forcing for ascent decreases and the high plains upslope flow
lessens during the afternoon. Precipitable water changes little,
so another day of low clouds, fog and showery type precipitation.
And, another day of unseasonably cool temperatures, especially
east of the Front Range. Highs on Tuesday only in the 40s...with
20s and 30s in the high country. Additional snow amounts anywhere
from 2 to 6 inches in the mountains and higher Front Range
foothills. Additional rain amounts on the plains anywhere from
0.05 inch in the far northeast to around a quarter inch near the
foothills. Airmass appears to be too cool and stable for t-storms
tomorrow mountains and plains.
Last but not least, the Winter Weather Advisory for mountain
zones 31..33 and 34 will remain in effect until 18z/Tuesday.
Should see snowfall rates decreasing by the afternoon.
.LONG TERM...(Tuesday night through Sunday)
Issued at 325 AM MDT Mon May 16 2016
Cool and cloudy start to the extended with an upper level low
spinning over southern CA. This low will weaken as it travels
eastward becoming an open trough by Wednesday afternoon/evening.
Continuing SW flow will keep a steady stream of moisture over NE
Colorado with cold fronts keeping conditions cooler and therefore
more stable. Fro Tuesday night into Wednesday conditions over the
plains will be cool with cloudy skies and chance of showers that
continue into the evening ours before clearing out overnight. Some
models suggesting the clouds will clear sooner on the far NE
plains allowing for some surface heating and therefore increased
instability. This could lead to isolated thunder on the plains
late Tuesday with heavier showers.
Wednesday temperatures will be cooler than average with highs only
getting into the lower 60s. A weak surface high on the plains will
help to keep precipitation out but conditions will remain cloudy.
In the mountains there is a chance of rain and snow showers at
higher elevations with isolated thunderstorms by the afternoon.
There is a deep closed off low entering the Pacific NW that will
allow ridging over NE Colorado on Thursday. There will be enough
moisture in the mountains however to keep a slight chance of
thunderstorms in the afternoon with rain and snow showers above
10,000 ft. Temperatures will rebound back to seasonal normals on
Thursday with highs in the upper 60s to lower 70s.
Friday and through the weekend starts a dry and warming trend. The
upper level low over the Pacific NW will continue to spin over
that region keeping prolonged ridging and therefore increasing
temps over CO. Look for highs into the 70s on Friday and possibly
lower 80s by Saturday and Sunday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 830 PM MDT Mon May 16 2016
IFR conditions will persist through at least Tuesday morning with
shallow upslope keeping rain showers, drizzle, and fog in place.
As rain decreases later tonight, drizzle and fog is expected to
become more prominent. Visibilities may drop to 1/4 to 1/2sm if
fog over the Front Range airports including KDEN 08Z-15Z. Should
see a slow improvement 15Z-18Z Tuesday with MVFR conditions
expected to develop Tuesday afternoon with some daytime heating
and weakening upslope component.
&&
.BOU Watches/Warnings/Advisories...
Winter Weather Advisory until noon MDT Tuesday for COZ033-034.
&&
$$
UPDATE...Barjenbruch
SHORT TERM...Baker
LONG TERM...Bowen
AVIATION...Barjenbruch
[top]
Area Forecast Discussion
National Weather Service Pueblo CO
551 PM MDT MON MAY 16 2016
.UPDATE...
Issued at 547 PM MDT Mon May 16 2016
Severe threat is done for this evening. Watch has been cancelled
for Las Animas and Baca Counties.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 327 PM MDT Mon May 16 2016
Currently...An upper low pressure system was located over the Great
Basin Mon afternoon, while at the sfc high pressure over the
Dakotas was supplying a low level northeasterly push into
Colorado. This was providing an ample amount of low level moisture
for the forecast area today, while disturbances aloft tapped into
the moisture for storm production. Isolated severe storms have
already occurred along the Colorado/New Mexico state line of SE
Colorado, with numerous showers and isolated storms elsewhere.
Extensive cloud cover has kept temps somewhat cool, 50s to lower
60s, and has throttled the fuel for widespread severe storm
activity.
Tonight and tomorrow...The upper low will gradually sink to the
south, then southwest, over the next 24 hrs, dropping into southern
Nevada and California through the day tomorrow. Numerous showers and
isolated thunderstorms are expected to continue through the evening
hours, then showers will linger through the night. Tomorrow the
process will repeat itself, but with the upper low a bit further to
the west and south, convection should diminish over the far eastern
plains while continuing over the western section of the CWA. The
severe threat will also drop south, out of the forecast area. Look
for cool temps tomorrow, with max temps only forecast to climb into
the 50s.
As for ongoing winter wx highlights, significant new accumulations
of wet spring snow for the higher elevations looks reasonable, and
had to issue an advisory for the SW mountains for the continued
threat there until late Tue night. The best window for periods of
heavy rain will likely be this evening through Tue morning, along
the I-25 corridor as well as the lower eastern slopes of the
southern Front Range. Moore
.LONG TERM...(Tuesday night through Monday)
Issued at 327 PM MDT Mon May 16 2016
Upper low settles into AZ Tue night, keeping strong upward
motion over the San Juan and La Garita mountains through the night.
Snow level will likely hang out around 10k-11k with several inches
of accumulation over the peaks. Will keep winter wx advisory in
place through the night, though impact may be limited somewhat by
warm road/ground temps staying near freezing. Tough to rule out
some lighter rain and snow showers across the remainder of the
region, best chances generally over the mountains and interior
valleys, least chance over the plains. Low turns to the corner and
heads east through AZ Wed, keeping precip going over the higher
terrain and most valleys through the day. Kept the advisory going
for now, though snow level will likely rise to above pass level by
afternoon as 700 mb temps begin to climb. Shallow upslope will keep
plains generally cloudy with a few showers possible, though
air mass east of the mountains looks too cool/stable for tsra. On
Thu, upper low weakens as it lifts northeastward across nrn NM and
srn CO. Expect precip Thu/Thu night to be fairly convective in
nature as low levels warm and destabilize somewhat, and will have a
mention of afternoon and evening tsra all areas in the afternoon and
early evening.
Upper ridge then migrates eastward through the state Fri/Sat which
should suppress convection somewhat, though residual moisture will
likely produce some mountain storms both days. Will need to watch
for some dryline storms Sat evening as deeper moisture pushes
north, with boundary along/near the KS border after 00z. Similar
set-up for Sun as Pacific NW upper trough pushes eastward, with
dryline lurking over the far sern plains and potential for high
based tsra over the mountains. Should see max temps Fri-Sat climb
back to above average readings, with 80s reappearing over portions
of the plains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 516 PM MDT Mon May 16 2016
Extended periods of mvfr to lifr are expected for the TAF sites
over the next couple of days, as a low pressure system slowly
moves through the region.
At KALS...expect periods of mvfr...and brief periods of ifr,
as rounds of showers and isold ts move through the valley through
tomorrow. Freezing levels should remain about 1000-1500 ft AGL on
tuesday.
KPUB and KCOS...TS should weaken early this eve, but numerous
showers will continue for the evening. Areas of fog likely to
develop by early morning, especially vicinity KCOS, and cigs
likely to remain IFR through the morning...possibly improving to
MVFR by afternoon. Freezing levels will be about 1000 ft AGL by
early Tue. ROSE
&&
.PUB Watches/Warnings/Advisories...
Winter Weather Advisory from noon Tuesday to midnight MDT
Wednesday night for COZ066-068.
Winter Weather Advisory until 6 AM MDT Tuesday for COZ058-060.
Winter Weather Advisory until noon MDT Tuesday for COZ081.
Winter Storm Warning until 6 AM MDT Wednesday for COZ082.
&&
$$
UPDATE...LW
SHORT TERM...MOORE
LONG TERM...PETERSEN
AVIATION...ROSE
[top]
Area Forecast Discussion
National Weather Service Grand Junction CO
508 PM MDT MON MAY 16 2016
.SHORT TERM...(This evening through Tuesday night)
Issued at 359 PM MDT Mon May 16 2016
Wet, dreary weather continues through the short term as an upper
level low spinning over northern Nevada moves south into the Great
Basin. However, this low will not track through the forecast area.
Rather, it will drop further south into Arizona. Regardless of its
track, ample moisture rotating with this storm will be pulled
into the region over the next couple of days. As a result, expect
a continuation of widespread showers and chance for storms plus
below normal temperatures in the forecast. Guidance temperatures
came in too warm so decided to bump temperatures down a few
degrees to reflect current trends. As with previous model runs,
best chance of precipitation is expected to be during the
afternoon and evening hours so grids continue to reflect that.
Seeing as how the gradient is not too impressive with this storm,
and that the jet core stays well south of the area, do not expect
any significant winds for the region apart from the occasional
gusty outflow wind with storms.
Most impressive QPF remains over the eastern Uinta mountains
and right along the northern divide tonight, but upper level
temps remain quite mild so not expecting any significant
snowfall. Tomorrow night will see the best chance for significant
snowfall especially down south. Orographics remain favorable for
upslope with winds generally remaining out of the southeast
through the overnight hours. However, after examining wet bulb
zero heights and upper level temperatures, do not think there
will be any major impacts for our mountain areas. Storm total
snowfall from tomorrow through Wednesday morning show the San
Juans receiving 4 to 8 inches. Seeing as how this will be over
several periods and the expectation that warm road surfaces will
melt any falling snow, chose to not issue any advisories at this
time. Will continue to monitor the situation and let future
shifts decide if highlights should be issued.
.LONG TERM...(Wednesday through Monday)
Issued at 359 PM MDT Mon May 16 2016
Wednesday will bring another day of widespread showers to the
region. The last pull of wraparound moisture from the departing
trough will keep decent shower coverage going through Thursday
morning before activity shifts to the higher terrain during the
afternoon. A "break" of sorts will finally arrive Friday as a
weak transitory ridge builds ahead of the next storm. However,
cannot rule out an afternoon shower or two during the afternoon
hours. As for the next storm, after remaining stationary off the
coast of the Pacific northwest for several days, it will finally
move onshore beginning Friday. Models indicate this massive low
pressure system will split with the lower portion following the
typical spring-time track. It is projected to drop down into the
Great Basin as early as Sunday night and bring yet another chance
for clouds and showers.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 506 PM MDT Mon May 16 2016
Stormy weather will continue tonight and tuesday as low pressure
remains over the area. Expect widespread showers and scattered
thunderstorms through the period with areas of IFR cigs possible,
and local ifr vsbys. mts will be obscured. Terminal sites may see
periods of ILS cigs as showers move through with brief mvfr and
ifr conditions. Gusty outflow winds to 40 mph and small hail will
accompany the strongest storms and snow levels will be running
between 9 and 10k today, falling to as low as 8k tonight.
&&
.HYDROLOGY...
Issued at 918 AM MDT Mon May 16 2016
With the forecast wet weather and expected warming temperatures
toward the end of the week, river levels are expected to
gradually rise over the next few weeks. Flows will generally
increase due to snowpack melting with some streams reaching near
bankfull at times. Use caution in and near swift currents.
&&
.GJT Watches/Warnings/Advisories...
CO...None.
UT...None.
&&
$$
SHORT TERM...MMS
LONG TERM...MMS
AVIATION...CC
HYDROLOGY...JAM
Area Forecast Discussion
National Weather Service Pueblo CO
141 PM MDT MON MAY 16 2016
.UPDATE...
Issued at 140 PM MDT Mon May 16 2016
Quick update for issuance of the Severe Thunderstorm Watch for Las
Animas and Baca counties until 03z tonight. Incorporated latest
obs and satellite data. Moore
&&
.SHORT TERM...(Today and tonight)
Issued at 450 AM MDT Mon May 16 2016
Multiple meteorological concerns over the forecast district during
the short term, including but not limited to locally heavy rainfall
potential, severe potential, higher elevation snow, areas of low
clouds/fog and temperatures, etc.
Forecast district currently graced by generally above seasonal mid-
May early morning temperatures, variable cloudiness in combination
with areas of low clouds and fog and isolated shower activity.
Latest forecast model soundings, real/near time data, computer
simulations and PV analysis indicate that upper disturbances will
combine with adequate atmospheric moisture and a moist northeasterly
surface surge to allow for the development of generally scattered to
numerous showers and isolated to scattered thunderstorms, once again
favoring the afternoon into the evening/night hours.
Some of these thunderstorms are expected to generate locally heavy
rainfall and also be capable of entering the strong to to severe
category as projected maximum localized capes, LI`s and 0-6 km
shears challenge/exceed 1600 J/Kg, -7C and 45 knots at times
respectively, especially over south-central and southeastern
sections of the forecast district.
At this time, the potential for stronger to severe storms favor
south-central and southeastern locations of the forecast district,
especially from this afternoon into this evening and have mentioned
severe potential(including the potential for large hail, damaging
winds and even an isolated tornado) in upcoming grids/zones over
eastern Las Animas and Baca continues to account for this
potential(although highest potential of organized severe storms
seems to favor locations such as portions of the Texas and Oklahoma
panhandles).
In addition, have also depicted locally heavy rain potential over
eastern portions of the forecast district, including the Interstate
25 corridor and associated burn scars, including but not limited to
the Waldo Canyon burn scar, etc. As always, WFO Pueblo will closely
monitor severe weather and flooding potential closely and issue
necessary highlights/advisories/warnings, etc. as needed.
Also, will maintain winter weather highlights from noon today into
at least Tuesday for Pikes Peak, Teller county and the Rampart Range
as well as for the eastern Sawatch Mountains and the Western
Mosquito Range, where significant late season is anticipated over
these locations during this time-frame.
Will also depict areas of fog and low clouds over several locations
at times during the near/short term in combination with continued
below seasonal mid-May maximum temperatures and near to above
seasonal minimum temperatures over the majority of the CWFA during
the next 24 hours.
.LONG TERM...(Tuesday through Sunday)
Issued at 450 AM MDT Mon May 16 2016
On Tue a large upr level low wl be centered ovr UT, with plenty of
mstr ovr the forecast area. The weather wl remain unsettled with
widespread pcpn chances over the mtns and high valleys. Over the
sern plains upslope flow continues and chances for light showers
look good...but closer to the mtns there may be better chances for
pcpn and accumulations. It looks like the swrn mtns wl be hardest
hit with snow on Tue...although the rest of the mtns wl also see
accumulations. Tue wl be the coolest day with highs in the mid 40s
to lower 50s at the lower elevations.
Tue night the upr low centered is expected to move south into AZ.
Snow is expected to continue ovr the mtns, with the best
accumulations still expected to be ovr the swrn mtns. the lower
elevations may see some light pcpn thru the night.
On Wed the upr low is expected to weaken and become an open wave and
being moving eastward acrs NM and CO. The mtns, high valleys and
I-25 corridor wl continue to see good chances for pcpn, while the
sern plains may just see some isold pcpn. Highs on Wed are expected
to be a little warmer, but wl still be below average with highs only
in the 50s at the lower elevations.
Wed night the upr trof is expected to move ovr far ern CO and pcpn
chances are expected to decrease ovr much of the area. On Thu there
wl still be enough moisture ovr the area that we should again sct or
high chances for pcpn ovr the mtns and high valleys, with isold pops
ovr the plains. temps should be a little warmer Thu but still below
average.
Finally, on Fri it looks drier ovr the area as a upr ridging
develops ovr ern co ahead of an upr low ovr OR and nrn CA. The
ridge shifts eastward ovr KS on Sat, with increasing southwest flow
ovr the forecast area. Chances for pcpn look mostly confined to the
mtn areas on Fri and Sat, but we may also see some isold
showers/tstms move out ovr the ern plains Sat afternoon and evening.
High temps Fri and Sat are expected to be above average. On Sun the
upr trof is forecast to move ovr NV which wl keep south to southwest
flow aloft ovr the forecast area and mainly dry conditions. However
there may still be some isold showers/tstms ovr the mtns and the dry
line may be near the KS border Sun afternoon.&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 450 AM MDT Mon May 16 2016
MVFR to localized IFR/LIFR ceilings and visibilities at times will
be possible over the KCOS and KPUB taf sites this morning due to
areas of low clouds and fog. Similar to the previous 24 hours,
periods of MVFR/IFR and LIFR conditions due to shower and
thunderstorm activity will be possible at times over the KALS, KCOS
and KPUB taf sites into tonight. In addition, the potential for
strong to severe thunderstorms exist primarily over south-central
and southeastern Colorado from late this morning into this evening,
although the potential does exist that stronger storms capable of
producing locally heavy rainfall, hail and gusty winds may be noted
in the vicinity of the KALS, KCOS, and KPUB taf sites respectively
from later today into this evening
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 450 AM MDT Mon May 16 2016
MVFR to localized IFR/LIFR ceilings and visibilities at times will
be possible over the KCOS and KPUB taf sites this morning due to
areas of low clouds and fog. Similar to the previous 24 hours,
periods of MVFR/IFR and LIFR conditions due to shower and
thunderstorm activity will be possible at times over the KALS, KCOS
and KPUB taf sites into tonight. In addition, the potential for
strong to severe thunderstorms exist primarily over south-central
and southeastern Colorado from late this morning into this evening,
although the potential does exist that stronger storms capable of
producing locally heavy rainfall, hail and gusty winds may be noted
in the vicinity of the KALS, KCOS, and KPUB taf sites respectively
from later today into this evening
&&
.PUB Watches/Warnings/Advisories...
Winter Weather Advisory from noon Tuesday to 6 AM MDT Wednesday
for COZ066-068.
Winter Weather Advisory until 6 AM MDT Tuesday for COZ058-060.
Winter Weather Advisory from 6 PM this evening to noon MDT
Tuesday for COZ081.
Winter Storm Warning until 6 AM MDT Wednesday for COZ082.
&&
$$
UPDATE...MOORE
SHORT TERM...77
LONG TERM...28
AVIATION...MOORE
Area Forecast Discussion
National Weather Service Denver/Boulder CO
1222 PM MDT MON MAY 16 2016
.UPDATE...
Issued at 1215 PM MDT Mon May 16 2016
convection now underway over the Front Range and western sections
of the Palmer Divide in Douglas County. Weather spotter just
reported small hail falling from a single t-storm south-southeast
of Castle Rock. Precipitation will continue to expand especially
over and east of the Front Range as upslope flow deepens and qg
ascent increases ahead of a vort lobe/shortwave trough rotating
up from southern Colorado. On another note, fog continues to
plague many areas with visibilities less than 2 miles in portions
of the I-25 corridor. Fog may be slow to dissipate today. Will
adjust afternoon forecast grids accordingly.
UPDATE Issued at 915 AM MDT Mon May 16 2016
Fog persists at this hour across most of the greater Denver metro
area...although web cams and surface obs reveal a significant
improvement in visibilities in areas roughly south of Interstate
70 and east of Aurora. The thickest fog was over northwest
sections of the metro area such as around Boulder and Broomfield
where prevailing vsbys were still below 1/4 mile. Should see this
heavy fog erode from southeast-to-northwest over the next hour or
two as slightly drier air flows down off the Palmer Divide and
with mixing of the boundary layer with passing rain showers. Vort
lobe/shortwave trough rotating northward over the CWA during the
next couple of hours will enhance this shower activity as noted
in the previous discussion. Isolated t-storms also a possibility
towards midday. Hail, brief heavy rain and perhaps a funnel cloud
or two all possible with these cells. At this time, will make
only minor adjustments to the ongoing forecast. Will also hang
onto the winter weather and dense fog highlights for now.
&&
.SHORT TERM...(Today and tonight)
Issued at 402 AM MDT Mon May 16 2016
Pockets of dense fog have formed in the Denver and Boulder areas
with visibilities less than a quarter mile at times. Partial
clearing after last evening`s period of rain allowed for strong
radiational cooling along parts of the i-25 urban corridor.
Visibilities at KDEN have been less than a quarter mile since
about 2 AM MDT and a co-worker driving up Davidson Mesa outside of
Boulder reported visibilities less than 100 feet. Other
observations from local airports show visibilities greater than a
mile and a half. Have issued a dense fog advisory for zones 39 and
40 until 10 AM MDT to handle the morning rush hour.
Otherwise, the forecast remains on track. A band of showers has
been moving over western Colorado this morning with some embedded
thunderstorms as late at 3:30 AM MDT. These showers should
progress into the north central mountains in the next few hours
and then over northeast Colorado later today. The approaching
upper trough will place Colorado under rising motions through this
evening. The airmass is plenty moist and slightly unstable at mid-
levels which will allow for an extended period of precipitation
through this afternoon and evening. Temperatures in the mountains
are expected to cool through today with snow levels eventually
coming down to 10000 feet or lower. Significant accumulations will
be possible on the peaks, ridges and higher elevation roadways, so
a Winter Weather Advisory will be in effect through Tuesday.
Temperatures are going to be much cooler than normal due to the
lack of sunshine and occurring precipitation. Areas of
precipitation are expected to continue into the evening and then
diminish overnight.
.LONG TERM...(Tuesday through Sunday)
Issued at 402 AM MDT Mon May 16 2016
Models have an upper closed low over Nevada into western Colorado
at 12z Tuesday. The upper low weakens and falls apart as it moves
slowly eastward and across the CWA as an open trough through
Wednesday night. The flow aloft will weak all four periods. The
models keep weak qg upward vertical velocity for the CWA into
Wednesday night. Models have easterly low level flow for the CWA
Tuesday, then southeasterly well into Wednesday. Winds should be
close to normal diurnal drainage patterns Wednesday night. Models
show quite a bit of moisture over the CWA well into Wednesday
before decrease overnight. The qpf Fields show measurable
precipitation across all the CWA Tuesday into Tuesday evening.
There is very little measurable precipitation noted Wednesday and
Wednesday evening for the plains, but some in the mountains. There
is some CAPE mainly in the mountains and foothills late day
Tuesday and late day Wednesday. Lapse rates are not very steep,
especially over the plains both late days periods. will go with
30-60% pops on Tuesday and Tuesday evening. Late day Wednesday`s
pops are similar in the mountains and foothills only. The plains
can expected 10-20%s. for temperatures, Tuesday`s highs are 1-3 C
warmer than today`s expected highs. Wednesday`s readings warm up
2-5 c above Tuesday`s readings.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1215 PM MDT Mon May 16 2016
will hang onto ils cigs and vsbys at denver area terminals for
the remainder of the afternoon. may not see vsbys rising above 3
miles all day, even with passing showers and t-storms. ceilings
now not expected to rise above 1000 ft agl all day at KDEN, KAPA
and KBJC.
&&
.BOU Watches/Warnings/Advisories...
Winter Weather Advisory until noon MDT Tuesday for COZ031-033-
034.
&&
$$
UPDATE...Baker
SHORT TERM...Dankers
LONG TERM...RJK
AVIATION...Baker
Area Forecast Discussion
National Weather Service Grand Junction CO
1129 AM MDT MON MAY 16 2016
updated aviation section
.UPDATE...
Issued at 918 AM MDT Mon May 16 2016
Rain/Snow line is at about 8300 feet this morning, but will rise
throughout the day. Snow accumulation level on roads as of 9am
looks to be above 10,000 ft at the high passes, so have refrained
from issuing any advisories today with impacts minimal. Will keep
an eye on precipitation development, but expecting short lived
convective showers and thunderstorms this afternoon. Short term
forecast models indicate downturn in activity after sunset when
snow would accumulate on the roads again. Expecting the best
thunderstorms to develop across the Four Corners today with hail
the main threat.
&&
.SHORT TERM...(Today through Tuesday night)
Issued at 254 AM MDT Mon May 16 2016
Energy rotating around an upper level low located over southern
Idaho will continue to bring showers and thunderstorms to much of
eastern Utah and western Colorado through Tuesday.
First wave working through the area this morning with showers and
thunderstorms driving east into the central mountains. Snow levels
remain above 9k and bulk of activity has been light so far, so no
plans on hoisting any winter highlights for narrow stretches of
our high mountain passes. Could see a few inches accumulate above
10k by this evening, but road surfaces remain warm and impact
should be minimal. Otherwise, it`s looking like another unsettled
day with a few stronger storms again expected as moisture and
additional energy pass through. Wind gusts to 50 mph not out of
the question along with small hail. Models have remained
aggressive with pops and QPF values peaking during the afternoon
and evening hours. See no reason to stray far from that thinking
and pop grids will be geared this direction.
As the low drops or sags south into Utah, colder air will slide
south with it. This will lower snow levels a bit by Tuesday
morning, possibly as low as 8k, but levels rise throughout the day
back to near 10k by afternoon. Overall a very similar weather day
is expected with showers and thunderstorms throughout the region
and some accumulating snowfall for the highest peaks. Best shot at
more significant snowfall will push into the San Juans late
Tuesday and Tuesday night when we see another stronger wave rotate
out of the digging low with a period of favorable orographics and
dynamics coming into play. This will generate more persistent
precipitation that may eventually lead to more significant
snowfall accumulations from Telluride southeast to Wolf Creek
Pass. Main impacts would be overnight Tuesday into Wednesday
morning and later shifts can take a look at the need for any sort
of winter highlights.
Temperatures will be running on the cool side of normal through
mid-week and have undercut guidance values a bit today and again
on Tuesday due to cloud cover and showers.
.LONG TERM...(Wednesday through Sunday)
Issued at 254 AM MDT Mon May 16 2016
The upper level low will slowly fill over the southern Great Basin
by the end of the week with the cool and unsettled weather slowly
abating as we close out the week. The low fills on Wednesday with
remnants getting kicked out by late Thursday. This will lead to a
decrease in the showers and also send in some warmer air aloft
which lifts snow levels back up to near 10k by Wednesday
afternoon. Scattered activity then lingers through Thursday
afternoon, favoring the higher terrain.
By Friday, the Pacific Northwest gets a taste of what we`ve been
experiencing as a deep area of low pressure sets up just off the
coast and gets cutoff. This system barely moves from Thursday
through Sunday. The location of the low will cause a ridge to form
to our east pushing the trough to the plains and keeping us
`relatively` dry. Some afternoon convection can`t be ruled out as
ample moisture will remain while daytime heating will help to
destabilize the atmosphere. After the first half of the week
though, the weather will show a marked improvement.
Temperatures will slowly warming up through the weekend.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1129 AM MDT Mon May 16 2016
Stormy weather continues across the region through the end of the
week. Expect widespread showers and isolated thunderstorms through the
period with areas of IFR cigs possible, especially over the
higher elevations. Terminal sites may see periods of ILS cigs as
showers move through. Gusty outflow winds to 50 mph and small hail
will accompany the strongest storms and snow levels will be
running between 9 and 10k today, falling to as low as 8k tonight.
Mountain obscuration likely over the next 24 hours.
&&
.HYDROLOGY...
Issued at 918 AM MDT Mon May 16 2016
With the forecast wet weather and expected warming temperatures
toward the end of the week, river levels are expected to
gradually rise over the next few weeks. Flows will generally
increase due to snowpack melting with some streams reaching near
bankfull at times. Use caution in and near swift currents.
&&
.GJT Watches/Warnings/Advisories...
CO...None.
UT...None.
&&
$$
UPDATE...JAM
SHORT TERM...JDC
LONG TERM...TGR/JDC
AVIATION...TGJT
HYDROLOGY...JAM
Area Forecast Discussion
National Weather Service Grand Junction CO
918 AM MDT MON MAY 16 2016
.UPDATE...
Issued at 918 AM MDT Mon May 16 2016
Rain/Snow line is at about 8300 feet this morning, but will rise
throughout the day. Snow accumulation level on roads as of 9am
looks to be above 10,000 ft at the high passes, so have refrained
from issuing any advisories today with impacts minimal. Will keep
an eye on precipitation development, but expecting short lived
convective showers and thunderstorms this afternoon. Short term
forecast models indicate downturn in activity after sunset when
snow would accumulate on the roads again. Expecting the best
thunderstorms to develop across the Four Corners today with hail
the main threat.
&&
.SHORT TERM...(Today through Tuesday night)
Issued at 254 AM MDT Mon May 16 2016
Energy rotating around an upper level low located over southern
Idaho will continue to bring showers and thunderstorms to much of
eastern Utah and western Colorado through Tuesday.
First wave working through the area this morning with showers and
thunderstorms driving east into the central mountains. Snow levels
remain above 9k and bulk of activity has been light so far, so no
plans on hoisting any winter highlights for narrow stretches of
our high mountain passes. Could see a few inches accumulate above
10k by this evening, but road surfaces remain warm and impact
should be minimal. Otherwise, it`s looking like another unsettled
day with a few stronger storms again expected as moisture and
additional energy pass through. Wind gusts to 50 mph not out of
the question along with small hail. Models have remained
aggressive with pops and QPF values peaking during the afternoon
and evening hours. See no reason to stray far from that thinking
and pop grids will be geared this direction.
As the low drops or sags south into Utah, colder air will slide
south with it. This will lower snow levels a bit by Tuesday
morning, possibly as low as 8k, but levels rise throughout the day
back to near 10k by afternoon. Overall a very similar weather day
is expected with showers and thunderstorms throughout the region
and some accumulating snowfall for the highest peaks. Best shot at
more significant snowfall will push into the San Juans late
Tuesday and Tuesday night when we see another stronger wave rotate
out of the digging low with a period of favorable orographics and
dynamics coming into play. This will generate more persistent
precipitation that may eventually lead to more significant
snowfall accumulations from Telluride southeast to Wolf Creek
Pass. Main impacts would be overnight Tuesday into Wednesday
morning and later shifts can take a look at the need for any sort
of winter highlights.
Temperatures will be running on the cool side of normal through
mid-week and have undercut guidance values a bit today and again
on Tuesday due to cloud cover and showers.
.LONG TERM...(Wednesday through Sunday)
Issued at 254 AM MDT Mon May 16 2016
The upper level low will slowly fill over the southern Great Basin
by the end of the week with the cool and unsettled weather slowly
abating as we close out the week. The low fills on Wednesday with
remnants getting kicked out by late Thursday. This will lead to a
decrease in the showers and also send in some warmer air aloft
which lifts snow levels back up to near 10k by Wednesday
afternoon. Scattered activity then lingers through Thursday
afternoon, favoring the higher terrain.
By Friday, the Pacific Northwest gets a taste of what we`ve been
experiencing as a deep area of low pressure sets up just off the
coast and gets cutoff. This system barely moves from Thursday
through Sunday. The location of the low will cause a ridge to form
to our east pushing the trough to the plains and keeping us
`relatively` dry. Some afternoon convection can`t be ruled out as
ample moisture will remain while daytime heating will help to
destabilize the atmosphere. After the first half of the week
though, the weather will show a marked improvement.
Temperatures will slowly warming up through the weekend.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 254 AM MDT Mon May 16 2016
Unsettled weather will remain in the region through Tuesday.
Expect widespread showers and isolated thunderstorms through the
period with areas of IFR cigs possible, especially over the
higher elevations. Terminal sites may see periods of ILS cigs as
showers move through. Gusty outflow winds to 50 mph and small hail
will accompany the strongest storms and snow levels will be
running between 9 and 10k today, falling to as low as 8k tonight.
Mountain obscuration likely over the next 24 hours.
&&
.HYDROLOGY...
Issued at 918 AM MDT Mon May 16 2016
With the forecast wet weather and expected warming temperatures
toward the end of the week, river levels are expected to
gradually rise over the next few weeks. Flows will generally
increase due to snowpack melting with some streams reaching near
bankfull at times. Use caution in and near swift currents.
&&
.GJT Watches/Warnings/Advisories...
CO...None.
UT...None.
&&
$$
UPDATE...JAM
SHORT TERM...JDC
LONG TERM...TGR/JDC
AVIATION...JDC
HYDROLOGY...JAM
Area Forecast Discussion
National Weather Service Denver/Boulder CO
821 PM MDT SUN MAY 15 2016
.UPDATE...
Issued at 659 PM MDT Sun May 15 2016
The second band of showers today is now moving off the foothills.
some lightning persisted to near Jefferson County Airport...but
for the most part these showers are again weakening as they move
to the plains. This is part of a large band of clouds that extend
to the west slope...but satellite loops show a large dry slot
moving into southwest Colorado. The HRRR and RAP models both show
a dry period from around 06z to 13z for the metro area.
The surface pattern has been weak this evening...but a surface low
is forecast to develop near trinidad late tonight and intensify
tomorrow morning. This will result in increasing upslope flow
along the urban corridor and palmer divide...with showers
redeveloping Monday morning and continuing through the day.
Coordinated with adjoining offices on winter weather
advisory...and will issue one for the higher mountain passes
for late tonight through noon Tuesday. Models indicate that some
higher elevations may see up to 30 inches of snow by the time the
storm is done with us. It is likely to be a very wet sloppy mess
with daytime highs in the higher passes reaching 32 tomorrow.
All in all the previous forecast has a good handle on system
development...but mav guidance is 5 degrees colder than met
guidance. With the clouds...upslope...and moisture am going to
lower max temps in eastern Colorado on Monday and drop higher
passes a degree or two.
&&
.SHORT TERM...(This evening through Monday)
Issued at 322 PM MDT Sun May 15 2016
Initial shower band moving east on the plains but has mostly
dissipated. A larger batch of showers and thunderstorms over the
mountains will spread onto the plains this evening. This has more
forcing and since it is a large area of rain it will bring higher
dew points with it, so it should survive better. Still expecting a
bit of a break later tonight, but then the low on the east side of
the mountains will start to wind up. Some question about the
amount of low level moisture that persists through the night.
Models seem a bit overdone, so I am showing mostly cloudy skies
but not into the fog/drizzle regime yet, at least around Denver. During
the night the best moisture convergence will be across Wyoming and
the Nebraska panhandle, but this should all slide southward Monday
morning with the lower levels saturating, upslope winds, and
persistent lift. Some uncertainty about the timing of this
progressing from north to south but at this time it looks like
this will be happening during the morning hours. Generally
expecting light but steady rainfall, but with upslope enhancement
over the east slopes of the Front Range. Snow level should also be
lowering a bit during the day, settling somewhere around 7-8
thousand feet on the east slopes with warmer low levels holding it
higher on the west side. Could be some heavy snow in the
afternoon, but warm temps will limit the impact in populated areas
so just the highest roads are of concern.
.LONG TERM...(Monday night through Sunday)
Issued at 322 PM MDT Sun May 15 2016
Monday night...a broad closed upper low will stretch from
Northwest NV into northwest CO. Weak QG ascent will be over the
cwa overnight as this trough makes its way south into AZ by 00z
Wednesday. At the surface...a secondary surge will enhance the
upslope along the Front Range Monday night. The mdls show moderate
to strong QG ascent at the surface through the evening...with the
east to southeast upslope fm the surface to around 600 mb. NAM12
forecast sounding show moist adiabatic lapse rates with the
airmass saturated through the layer. There could be an isolated
tstm in the mountains Monday evening but it looks too stable
across the Urban Corridor and northeast plains with the possible
exception of the Palmer Divide. Overrunning type of setup Monday
night with the colder air below undercutting a fairly strong
inversion just above 700 mb. east and southeast facing aspects
above 9 thousand feet could receive 8 to 12 inches of snowfall by
tuesday morning...but not as much west of the Continental Divide.
No highlights yet but am learning more towards advisory type
snowfall vs warning at this time for the Front Range east of the
Continental Divide and possibly the higher foothills. The
foothills will see a accumulating snowfall above 8 thousand feet
with a steady mix of rain and snow down to 6500 feet. We could
possibly see a mix of rain/snow over the palmer divide above 6
thousand feet by tuesday morning. The mix of rain/snow in the
foothills should help alleviate any potential flooding risk as
well. Tuesday...a deep southeasterly upslope flow will be present
but the wind will not be as strong. Wl keep some light snow or
rain/snow mix in the mountains through the day...with higher pops
for light rain in and near the foothills/Palmer Divide as well. Wl
keep the mention of tstms in the grids but mainly over the
mountains. Tuesday night into Wednesday...the main area of
pcpn continues to get dragged to the south. There is still enough
moisture and some weak forcing around for showers...especially
over the mountain but the overall coverage will be decreasing.
The weakening trough finally shifts to the east of CO by Thu with
a drier and more subsident northwesterly flow aloft. An upper
level ridge will finally set up over the region late Thursday and
continue into Saturday. It will be much warmer by the weekend with
the more typical pattern of aftn/evng thunderstorms on Friday and
Saturday. The mdls continue to show a large upper trough over the
Pacific Northwest by the weekend...with an increasing southwesterly
flow aloft over CO by Sunday.
&&
.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 322 PM MDT Sun May 15 2016
The showers moving through the metro area will be followed by one
or two more bands of rain this evening...but it looks dry from 06z
until at least 13z. The winds have been the big question
today...other than the gusty winds with showers...it has been
difficult to pin down directions. This will become easier tomorrow
with the deepening upslope flow we will settle on north to
northeast winds for much of the day. Ceilings of 030 to 060 with
the showers will rise a bit overnight...then drop to mvfr monday
morning...with areas of ifr.
&&
.BOU Watches/Warnings/Advisories...winter weather advisory for
mountain zones...31...33...34 from 3am tonight to noon Tuesday.
&&
$$
UPDATE...RTG
SHORT TERM...Gimmestad
LONG TERM...Cooper
AVIATION...Gimmestad
Area Forecast Discussion
National Weather Service Grand Junction CO
403 PM MDT TUE MAY 17 2016
.SHORT TERM...(Tonight through Wednesday night)
Issued at 403 PM MDT Tue May 17 2016
Southerly flow continues to pump in moisture thanks to the low
pressure that is to our west. Instability wasn`t as strong today
so the intensity of the showers and storms was weaker than seen
yesterday though a few heavier showers have popped. Most of the
precipitation will end a few hours after sunset though some
showers, generally south, will continue overnight. Some snow can
be expected above 10,000 feet tonight but expect minimal impacts
on roadways so held off on issuing any advisories.
By Wednesday morning, the low will have shifted to southern
Arizona but moisture will continue to stream into the area. Once
again, afternoon showers and storms will form mid-morning onwards.
H7 winds remain light so gusty winds not too much of a concern
with storms that fire though some small hail is possible along
with heavier rain at times.
.LONG TERM...(Thursday through Tuesday)
Issued at 403 PM MDT Tue May 17 2016
By Thursday morning, finally, the low pressure center will open
up, become an open wave, and shift to eastern Colorado. A ridge
will build in but plenty of moisture will remain in the atmosphere
allowing the more usual afternoon showers and storms to form.
As this occurs, a very deep area of low pressure will drop down
into the Pacific northwest and become somewhat stationary. Model
runs have changed where the low will set up so confidence a bit
shaky in that regard. One thing that has remained constant though is
that this low will tighten the pressure gradient considerably
causing gusty winds across much of the Great Basin. Our area can
expect to see winds picking up Friday and continue each afternoon
through Sunday. Best upper level support for this system looks to
stay to our north so expect some showers at times through Tuesday
but nothing too widespread.
Temperatures will jump to near or above normals Friday and
Saturday before dropping a few degrees below Sunday onwards thanks
to increased clouds.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 335 PM MDT Tue May 17 2016
The threat of precipitation will remain in place over much of
western Colorado and eastern Utah over the next 24 hours.
Thunderstorm activity will expand through this afternoon. ILS
break points may be exceeded at times as showers work over the
forecast terminals, but for the most part VFR conditions will
prevail. Storms will intensify in response to daytime warming
resulting in increased rainfall rates and some lowered flight
criteria may be possible at times during the afternoon and early
evening. Expect areas of terrain obscuration over the next 24
hours as well in this wet pattern.
&&
.HYDROLOGY...
Issued at 400 AM MDT Tue May 17 2016
Wet weather through midweek combined with rising temperatures
toward the end of the week are expected to drive river levels
gradually higher. In fact, over the next few weeks increased
flows will primarily be the result of melting snowpack. This will
cause rivers and streams to swell causing some streams to reach
bankfull. Use caution in and near swift currents.
&&
$$
SHORT TERM...TGR
LONG TERM...TGR
AVIATION...JAM
HYDROLOGY...NL
Area Forecast Discussion
National Weather Service Grand Junction CO
1142 AM MDT TUE MAY 17 2016
.UPDATE...
Issued at 1142 AM MDT Tue May 17 2016
Shower and thunderstorm activity is increasing as expected. Storm
motion today will be mainly from south to north or from the
southeast to northwest over NE Utah and NW Colorado. Small hail,
frequent lightning and gusty winds will be possible with stronger
thunderstorms.
&&
.SHORT TERM...(Today through Wednesday)
Issued at 400 AM MDT Tue May 17 2016
Moisture will continue to move over the area through midweek as a
low pressure system featuring a distinct pair of low centers
circulates over the west. For today, the low circulation over
east-central Utah will shift to the northwest as the Nevada
circulation drops southeastward toward Las Vegas. The resultant
south to north component of mid-level flow will continue to supply
moisture to the area and precipitable water values are expected
to remain near 0.50 of an inch. Daytime warming combined with
divergence aloft will provide the instability and lift for
scattered to numerous coverage of showers and embedded
thunderstorms. As mentioned in the previous discussion, the
pressure gradient in the lower levels flow will remain relatively
weak with light winds the result with the exception of outflow
from thunderstorms.
Moist convection will decline overnight as the airmass over the
region cools and becomes more stable. However, as the Las Vegas
low center moves to southern Arizona, the southern half of the
forecast area will fall under increased diffluence/divergence
aloft. As a result, showers and a few embedded thunderstorms are
expected to persist into Wednesday morning while precipitation
largely ends north of the i-70 corridor. Snow levels dip below
pass levels in the San Juan mountains, however expect the
relatively mild temperatures will limit impact to road surfaces.
The slowly moving low center will shift to west-central New Mexico
Wednesday resulting in continued unsettled conditions over the
area. Expect daytime temperatures to remain below normal through
midweek in response to cloudy/showery weather with lows near
normal again tonight.
.LONG TERM...(Wednesday night through Monday)
Issued at 400 AM MDT Tue May 17 2016
The last pull of wraparound moisture from the departing trough
will keep decent shower coverage going through Thursday morning
before activity shifts to the higher terrain during the afternoon.
A "break" of sorts will finally arrive Friday as a weak transitory
ridge builds ahead of the next storm. However, cannot rule out an
afternoon shower or two. As for the next storm, after remaining
stationary off the coast of the Pacific northwest for several
days, it will finally move onshore beginning Friday. Models
indicated this massive low pressure system will split with the
lower portion following the typical springtime track. This system
is projected to drop down over the Great Basin as early as Sunday
night, bringing yet another chance for clouds and showers Monday.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1142 AM MDT Tue May 17 2016
The threat of precipitation will remain in place over much of
western Colorado and eastern Utah over the next 24 hours.
Thunderstorm activity will expand through this afternoon. ILS
break points may be exceeded at times as showers work over the
forecast terminals, but for the most part VFR conditions will
prevail. Storms will intensify in response to daytime warming
resulting in increased rainfall rates and some lowered flight
criteria may be possible at times during the afternoon and early
evening. Expect areas of terrain obscuration over the next 24
hours as well in this wet pattern.
&&
.HYDROLOGY...
Issued at 400 AM MDT Tue May 17 2016
Wet weather through midweek combined with rising temperatures
toward the end of the week are expected to drive river levels
gradually higher. In fact, over the next few weeks increased
flows will primarily be the result of melting snowpack. This will
cause rivers and streams to swell causing some streams to reach
bankfull. Use caution in and near swift currents.
&&
.GJT Watches/Warnings/Advisories...
CO...None.
UT...None.
&&
$$
UPDATE...JAM
SHORT TERM...NL
LONG TERM...MMS/NL
AVIATION...JAM
HYDROLOGY...JAM/NL
[top]
Area Forecast Discussion
National Weather Service Denver/Boulder CO
830 PM MDT MON MAY 16 2016
.UPDATE...
Issued at 830 PM MDT Mon May 16 2016
Radar shows widespread showers across the plains and Front Range.
Current snow level ranged from around 7000-7500 feet in the
southern foothills, to down as low as 6000 feet near the Wyoming
border as Cheyenne Wyoming had switched over to snow in the last
couple hours. Main precipitation shield is just east of I-25 but
lots of drizzle farther west, with another batch of heavier precip
and snowfall in the mountains around Summit and Park counties. The
main precip area on the plains is shifting slightly westward as
another surge was noted in Northeast Colorado, so rain will
continue through the rest of this evening and then maybe only
slowly decrease through the rest of the night as upslope component
weakens. Even then, drizzle and areas of fog should remain behind
and continue into Tuesday morning with the very moist and ever so
slight upslope component still in place.
With regard to snow in the mountains, the orographic forcing is
rather weak but still convective enough for a heavy burst of snow
this evening in the Summit and Park county areas. Will keep the
advisories going here, but did cancel the advisory farther
northwest where snow has been slow to develop in zone 31 near the
Rabbit Ears Pass area.
&&
.SHORT TERM...(This afternoon through Tuesday)
Issued at 325 AM MDT Mon May 16 2016
500mb low centered over southwest Idaho at the present time is
forecast to track south-southeastward to over central Utah by 06z
tonight. From there models show the low curving southwestward
over the lower Colorado River valley south of Las Vegas by late
Tuesday afternoon. Near zonal mid-level flow on the south side of
this low continues to feed ample amounts moisture over Colorado.
East of the mountains this flow curves northeastward producing a
wide region of weak to moderate qg ascent. Even as the upper low
tracks south across Utah tonight, models show north central and
northeast Colorado under large scale ascent. Returning to this
afternoon...a shortwave trough/vort lobe rotating around the
southeast quad of the upper trough presently aligning from NW
Colorado to SE Colorado. Models show this feature and the
convection its generating swinging newrd across NE Colorado
between 23z/Mon-06Z/Tue. If it were not for the heavy low cloud
cover and chilly temperatures on the plains, mid-level shear,
instability and lift would be adequate to spawn a few strong if
not severe t-storms. As it stands, the few t-storms that have
managed to form over the Palmer Divide have pretty much collapsed
as they moved into the far less favorable environment on the
plains. One last comment, fog blanketing much of northeast
Colorado and many mountain locales since late last night has shown
little signs of dissipating. Many areas along the Front Range
foothills are still reporting vsbys below 5 miles.
Overnight...height and pressure falls on the west slope of
Colorado will further enhance the moist upslope flow up against
the east face of the Front Range mountains. Models indicate weak
to moderate qg ascent moving over northeast and north central
Colorado with the passing shortwave this evening. Model qpf
amounts on the plains by 12z/Tue in the 0.35 to 0.70 inch range.
QPf for the Front Range mountains and foothills in the 0.50 to
0.95 inch range. Snow level based on wetbulb zero anywhere from
7500 to 8500 ft this evening, then anywhere from 6000 to 7000
feet after midnight. Could see snow totals by morning anywhere
from 5-9 inches on east facing slopes above 9000 feet...and 3-6
inches from 7000 to 9000 feet. It`s possible we could see an inch
or so of very wet snow near the base of the foothills and on the
Palmer Divide. Do not expect to see any snow accumulation in the
Denver metro area except maybe a dusting on lawns in the higher
western and southern suburbs. Lastly, should also continue to
see areas of fog with the moist upslope flow...especially up
against the Front Range.
On Tuesday...as the upper low slowly moves away from Colorado
forcing for ascent decreases and the high plains upslope flow
lessens during the afternoon. Precipitable water changes little,
so another day of low clouds, fog and showery type precipitation.
And, another day of unseasonably cool temperatures, especially
east of the Front Range. Highs on Tuesday only in the 40s...with
20s and 30s in the high country. Additional snow amounts anywhere
from 2 to 6 inches in the mountains and higher Front Range
foothills. Additional rain amounts on the plains anywhere from
0.05 inch in the far northeast to around a quarter inch near the
foothills. Airmass appears to be too cool and stable for t-storms
tomorrow mountains and plains.
Last but not least, the Winter Weather Advisory for mountain
zones 31..33 and 34 will remain in effect until 18z/Tuesday.
Should see snowfall rates decreasing by the afternoon.
.LONG TERM...(Tuesday night through Sunday)
Issued at 325 AM MDT Mon May 16 2016
Cool and cloudy start to the extended with an upper level low
spinning over southern CA. This low will weaken as it travels
eastward becoming an open trough by Wednesday afternoon/evening.
Continuing SW flow will keep a steady stream of moisture over NE
Colorado with cold fronts keeping conditions cooler and therefore
more stable. Fro Tuesday night into Wednesday conditions over the
plains will be cool with cloudy skies and chance of showers that
continue into the evening ours before clearing out overnight. Some
models suggesting the clouds will clear sooner on the far NE
plains allowing for some surface heating and therefore increased
instability. This could lead to isolated thunder on the plains
late Tuesday with heavier showers.
Wednesday temperatures will be cooler than average with highs only
getting into the lower 60s. A weak surface high on the plains will
help to keep precipitation out but conditions will remain cloudy.
In the mountains there is a chance of rain and snow showers at
higher elevations with isolated thunderstorms by the afternoon.
There is a deep closed off low entering the Pacific NW that will
allow ridging over NE Colorado on Thursday. There will be enough
moisture in the mountains however to keep a slight chance of
thunderstorms in the afternoon with rain and snow showers above
10,000 ft. Temperatures will rebound back to seasonal normals on
Thursday with highs in the upper 60s to lower 70s.
Friday and through the weekend starts a dry and warming trend. The
upper level low over the Pacific NW will continue to spin over
that region keeping prolonged ridging and therefore increasing
temps over CO. Look for highs into the 70s on Friday and possibly
lower 80s by Saturday and Sunday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 830 PM MDT Mon May 16 2016
IFR conditions will persist through at least Tuesday morning with
shallow upslope keeping rain showers, drizzle, and fog in place.
As rain decreases later tonight, drizzle and fog is expected to
become more prominent. Visibilities may drop to 1/4 to 1/2sm if
fog over the Front Range airports including KDEN 08Z-15Z. Should
see a slow improvement 15Z-18Z Tuesday with MVFR conditions
expected to develop Tuesday afternoon with some daytime heating
and weakening upslope component.
&&
.BOU Watches/Warnings/Advisories...
Winter Weather Advisory until noon MDT Tuesday for COZ033-034.
&&
$$
UPDATE...Barjenbruch
SHORT TERM...Baker
LONG TERM...Bowen
AVIATION...Barjenbruch
[top]
Area Forecast Discussion
National Weather Service Pueblo CO
551 PM MDT MON MAY 16 2016
.UPDATE...
Issued at 547 PM MDT Mon May 16 2016
Severe threat is done for this evening. Watch has been cancelled
for Las Animas and Baca Counties.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 327 PM MDT Mon May 16 2016
Currently...An upper low pressure system was located over the Great
Basin Mon afternoon, while at the sfc high pressure over the
Dakotas was supplying a low level northeasterly push into
Colorado. This was providing an ample amount of low level moisture
for the forecast area today, while disturbances aloft tapped into
the moisture for storm production. Isolated severe storms have
already occurred along the Colorado/New Mexico state line of SE
Colorado, with numerous showers and isolated storms elsewhere.
Extensive cloud cover has kept temps somewhat cool, 50s to lower
60s, and has throttled the fuel for widespread severe storm
activity.
Tonight and tomorrow...The upper low will gradually sink to the
south, then southwest, over the next 24 hrs, dropping into southern
Nevada and California through the day tomorrow. Numerous showers and
isolated thunderstorms are expected to continue through the evening
hours, then showers will linger through the night. Tomorrow the
process will repeat itself, but with the upper low a bit further to
the west and south, convection should diminish over the far eastern
plains while continuing over the western section of the CWA. The
severe threat will also drop south, out of the forecast area. Look
for cool temps tomorrow, with max temps only forecast to climb into
the 50s.
As for ongoing winter wx highlights, significant new accumulations
of wet spring snow for the higher elevations looks reasonable, and
had to issue an advisory for the SW mountains for the continued
threat there until late Tue night. The best window for periods of
heavy rain will likely be this evening through Tue morning, along
the I-25 corridor as well as the lower eastern slopes of the
southern Front Range. Moore
.LONG TERM...(Tuesday night through Monday)
Issued at 327 PM MDT Mon May 16 2016
Upper low settles into AZ Tue night, keeping strong upward
motion over the San Juan and La Garita mountains through the night.
Snow level will likely hang out around 10k-11k with several inches
of accumulation over the peaks. Will keep winter wx advisory in
place through the night, though impact may be limited somewhat by
warm road/ground temps staying near freezing. Tough to rule out
some lighter rain and snow showers across the remainder of the
region, best chances generally over the mountains and interior
valleys, least chance over the plains. Low turns to the corner and
heads east through AZ Wed, keeping precip going over the higher
terrain and most valleys through the day. Kept the advisory going
for now, though snow level will likely rise to above pass level by
afternoon as 700 mb temps begin to climb. Shallow upslope will keep
plains generally cloudy with a few showers possible, though
air mass east of the mountains looks too cool/stable for tsra. On
Thu, upper low weakens as it lifts northeastward across nrn NM and
srn CO. Expect precip Thu/Thu night to be fairly convective in
nature as low levels warm and destabilize somewhat, and will have a
mention of afternoon and evening tsra all areas in the afternoon and
early evening.
Upper ridge then migrates eastward through the state Fri/Sat which
should suppress convection somewhat, though residual moisture will
likely produce some mountain storms both days. Will need to watch
for some dryline storms Sat evening as deeper moisture pushes
north, with boundary along/near the KS border after 00z. Similar
set-up for Sun as Pacific NW upper trough pushes eastward, with
dryline lurking over the far sern plains and potential for high
based tsra over the mountains. Should see max temps Fri-Sat climb
back to above average readings, with 80s reappearing over portions
of the plains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 516 PM MDT Mon May 16 2016
Extended periods of mvfr to lifr are expected for the TAF sites
over the next couple of days, as a low pressure system slowly
moves through the region.
At KALS...expect periods of mvfr...and brief periods of ifr,
as rounds of showers and isold ts move through the valley through
tomorrow. Freezing levels should remain about 1000-1500 ft AGL on
tuesday.
KPUB and KCOS...TS should weaken early this eve, but numerous
showers will continue for the evening. Areas of fog likely to
develop by early morning, especially vicinity KCOS, and cigs
likely to remain IFR through the morning...possibly improving to
MVFR by afternoon. Freezing levels will be about 1000 ft AGL by
early Tue. ROSE
&&
.PUB Watches/Warnings/Advisories...
Winter Weather Advisory from noon Tuesday to midnight MDT
Wednesday night for COZ066-068.
Winter Weather Advisory until 6 AM MDT Tuesday for COZ058-060.
Winter Weather Advisory until noon MDT Tuesday for COZ081.
Winter Storm Warning until 6 AM MDT Wednesday for COZ082.
&&
$$
UPDATE...LW
SHORT TERM...MOORE
LONG TERM...PETERSEN
AVIATION...ROSE
Area Forecast Discussion
National Weather Service Grand Junction CO
508 PM MDT MON MAY 16 2016
.SHORT TERM...(This evening through Tuesday night)
Issued at 359 PM MDT Mon May 16 2016
Wet, dreary weather continues through the short term as an upper
level low spinning over northern Nevada moves south into the Great
Basin. However, this low will not track through the forecast area.
Rather, it will drop further south into Arizona. Regardless of its
track, ample moisture rotating with this storm will be pulled
into the region over the next couple of days. As a result, expect
a continuation of widespread showers and chance for storms plus
below normal temperatures in the forecast. Guidance temperatures
came in too warm so decided to bump temperatures down a few
degrees to reflect current trends. As with previous model runs,
best chance of precipitation is expected to be during the
afternoon and evening hours so grids continue to reflect that.
Seeing as how the gradient is not too impressive with this storm,
and that the jet core stays well south of the area, do not expect
any significant winds for the region apart from the occasional
gusty outflow wind with storms.
Most impressive QPF remains over the eastern Uinta mountains
and right along the northern divide tonight, but upper level
temps remain quite mild so not expecting any significant
snowfall. Tomorrow night will see the best chance for significant
snowfall especially down south. Orographics remain favorable for
upslope with winds generally remaining out of the southeast
through the overnight hours. However, after examining wet bulb
zero heights and upper level temperatures, do not think there
will be any major impacts for our mountain areas. Storm total
snowfall from tomorrow through Wednesday morning show the San
Juans receiving 4 to 8 inches. Seeing as how this will be over
several periods and the expectation that warm road surfaces will
melt any falling snow, chose to not issue any advisories at this
time. Will continue to monitor the situation and let future
shifts decide if highlights should be issued.
.LONG TERM...(Wednesday through Monday)
Issued at 359 PM MDT Mon May 16 2016
Wednesday will bring another day of widespread showers to the
region. The last pull of wraparound moisture from the departing
trough will keep decent shower coverage going through Thursday
morning before activity shifts to the higher terrain during the
afternoon. A "break" of sorts will finally arrive Friday as a
weak transitory ridge builds ahead of the next storm. However,
cannot rule out an afternoon shower or two during the afternoon
hours. As for the next storm, after remaining stationary off the
coast of the Pacific northwest for several days, it will finally
move onshore beginning Friday. Models indicate this massive low
pressure system will split with the lower portion following the
typical spring-time track. It is projected to drop down into the
Great Basin as early as Sunday night and bring yet another chance
for clouds and showers.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 506 PM MDT Mon May 16 2016
Stormy weather will continue tonight and tuesday as low pressure
remains over the area. Expect widespread showers and scattered
thunderstorms through the period with areas of IFR cigs possible,
and local ifr vsbys. mts will be obscured. Terminal sites may see
periods of ILS cigs as showers move through with brief mvfr and
ifr conditions. Gusty outflow winds to 40 mph and small hail will
accompany the strongest storms and snow levels will be running
between 9 and 10k today, falling to as low as 8k tonight.
&&
.HYDROLOGY...
Issued at 918 AM MDT Mon May 16 2016
With the forecast wet weather and expected warming temperatures
toward the end of the week, river levels are expected to
gradually rise over the next few weeks. Flows will generally
increase due to snowpack melting with some streams reaching near
bankfull at times. Use caution in and near swift currents.
&&
.GJT Watches/Warnings/Advisories...
CO...None.
UT...None.
&&
$$
SHORT TERM...MMS
LONG TERM...MMS
AVIATION...CC
HYDROLOGY...JAM
Area Forecast Discussion
National Weather Service Pueblo CO
141 PM MDT MON MAY 16 2016
.UPDATE...
Issued at 140 PM MDT Mon May 16 2016
Quick update for issuance of the Severe Thunderstorm Watch for Las
Animas and Baca counties until 03z tonight. Incorporated latest
obs and satellite data. Moore
&&
.SHORT TERM...(Today and tonight)
Issued at 450 AM MDT Mon May 16 2016
Multiple meteorological concerns over the forecast district during
the short term, including but not limited to locally heavy rainfall
potential, severe potential, higher elevation snow, areas of low
clouds/fog and temperatures, etc.
Forecast district currently graced by generally above seasonal mid-
May early morning temperatures, variable cloudiness in combination
with areas of low clouds and fog and isolated shower activity.
Latest forecast model soundings, real/near time data, computer
simulations and PV analysis indicate that upper disturbances will
combine with adequate atmospheric moisture and a moist northeasterly
surface surge to allow for the development of generally scattered to
numerous showers and isolated to scattered thunderstorms, once again
favoring the afternoon into the evening/night hours.
Some of these thunderstorms are expected to generate locally heavy
rainfall and also be capable of entering the strong to to severe
category as projected maximum localized capes, LI`s and 0-6 km
shears challenge/exceed 1600 J/Kg, -7C and 45 knots at times
respectively, especially over south-central and southeastern
sections of the forecast district.
At this time, the potential for stronger to severe storms favor
south-central and southeastern locations of the forecast district,
especially from this afternoon into this evening and have mentioned
severe potential(including the potential for large hail, damaging
winds and even an isolated tornado) in upcoming grids/zones over
eastern Las Animas and Baca continues to account for this
potential(although highest potential of organized severe storms
seems to favor locations such as portions of the Texas and Oklahoma
panhandles).
In addition, have also depicted locally heavy rain potential over
eastern portions of the forecast district, including the Interstate
25 corridor and associated burn scars, including but not limited to
the Waldo Canyon burn scar, etc. As always, WFO Pueblo will closely
monitor severe weather and flooding potential closely and issue
necessary highlights/advisories/warnings, etc. as needed.
Also, will maintain winter weather highlights from noon today into
at least Tuesday for Pikes Peak, Teller county and the Rampart Range
as well as for the eastern Sawatch Mountains and the Western
Mosquito Range, where significant late season is anticipated over
these locations during this time-frame.
Will also depict areas of fog and low clouds over several locations
at times during the near/short term in combination with continued
below seasonal mid-May maximum temperatures and near to above
seasonal minimum temperatures over the majority of the CWFA during
the next 24 hours.
.LONG TERM...(Tuesday through Sunday)
Issued at 450 AM MDT Mon May 16 2016
On Tue a large upr level low wl be centered ovr UT, with plenty of
mstr ovr the forecast area. The weather wl remain unsettled with
widespread pcpn chances over the mtns and high valleys. Over the
sern plains upslope flow continues and chances for light showers
look good...but closer to the mtns there may be better chances for
pcpn and accumulations. It looks like the swrn mtns wl be hardest
hit with snow on Tue...although the rest of the mtns wl also see
accumulations. Tue wl be the coolest day with highs in the mid 40s
to lower 50s at the lower elevations.
Tue night the upr low centered is expected to move south into AZ.
Snow is expected to continue ovr the mtns, with the best
accumulations still expected to be ovr the swrn mtns. the lower
elevations may see some light pcpn thru the night.
On Wed the upr low is expected to weaken and become an open wave and
being moving eastward acrs NM and CO. The mtns, high valleys and
I-25 corridor wl continue to see good chances for pcpn, while the
sern plains may just see some isold pcpn. Highs on Wed are expected
to be a little warmer, but wl still be below average with highs only
in the 50s at the lower elevations.
Wed night the upr trof is expected to move ovr far ern CO and pcpn
chances are expected to decrease ovr much of the area. On Thu there
wl still be enough moisture ovr the area that we should again sct or
high chances for pcpn ovr the mtns and high valleys, with isold pops
ovr the plains. temps should be a little warmer Thu but still below
average.
Finally, on Fri it looks drier ovr the area as a upr ridging
develops ovr ern co ahead of an upr low ovr OR and nrn CA. The
ridge shifts eastward ovr KS on Sat, with increasing southwest flow
ovr the forecast area. Chances for pcpn look mostly confined to the
mtn areas on Fri and Sat, but we may also see some isold
showers/tstms move out ovr the ern plains Sat afternoon and evening.
High temps Fri and Sat are expected to be above average. On Sun the
upr trof is forecast to move ovr NV which wl keep south to southwest
flow aloft ovr the forecast area and mainly dry conditions. However
there may still be some isold showers/tstms ovr the mtns and the dry
line may be near the KS border Sun afternoon.&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 450 AM MDT Mon May 16 2016
MVFR to localized IFR/LIFR ceilings and visibilities at times will
be possible over the KCOS and KPUB taf sites this morning due to
areas of low clouds and fog. Similar to the previous 24 hours,
periods of MVFR/IFR and LIFR conditions due to shower and
thunderstorm activity will be possible at times over the KALS, KCOS
and KPUB taf sites into tonight. In addition, the potential for
strong to severe thunderstorms exist primarily over south-central
and southeastern Colorado from late this morning into this evening,
although the potential does exist that stronger storms capable of
producing locally heavy rainfall, hail and gusty winds may be noted
in the vicinity of the KALS, KCOS, and KPUB taf sites respectively
from later today into this evening
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 450 AM MDT Mon May 16 2016
MVFR to localized IFR/LIFR ceilings and visibilities at times will
be possible over the KCOS and KPUB taf sites this morning due to
areas of low clouds and fog. Similar to the previous 24 hours,
periods of MVFR/IFR and LIFR conditions due to shower and
thunderstorm activity will be possible at times over the KALS, KCOS
and KPUB taf sites into tonight. In addition, the potential for
strong to severe thunderstorms exist primarily over south-central
and southeastern Colorado from late this morning into this evening,
although the potential does exist that stronger storms capable of
producing locally heavy rainfall, hail and gusty winds may be noted
in the vicinity of the KALS, KCOS, and KPUB taf sites respectively
from later today into this evening
&&
.PUB Watches/Warnings/Advisories...
Winter Weather Advisory from noon Tuesday to 6 AM MDT Wednesday
for COZ066-068.
Winter Weather Advisory until 6 AM MDT Tuesday for COZ058-060.
Winter Weather Advisory from 6 PM this evening to noon MDT
Tuesday for COZ081.
Winter Storm Warning until 6 AM MDT Wednesday for COZ082.
&&
$$
UPDATE...MOORE
SHORT TERM...77
LONG TERM...28
AVIATION...MOORE
Area Forecast Discussion
National Weather Service Denver/Boulder CO
1222 PM MDT MON MAY 16 2016
.UPDATE...
Issued at 1215 PM MDT Mon May 16 2016
convection now underway over the Front Range and western sections
of the Palmer Divide in Douglas County. Weather spotter just
reported small hail falling from a single t-storm south-southeast
of Castle Rock. Precipitation will continue to expand especially
over and east of the Front Range as upslope flow deepens and qg
ascent increases ahead of a vort lobe/shortwave trough rotating
up from southern Colorado. On another note, fog continues to
plague many areas with visibilities less than 2 miles in portions
of the I-25 corridor. Fog may be slow to dissipate today. Will
adjust afternoon forecast grids accordingly.
UPDATE Issued at 915 AM MDT Mon May 16 2016
Fog persists at this hour across most of the greater Denver metro
area...although web cams and surface obs reveal a significant
improvement in visibilities in areas roughly south of Interstate
70 and east of Aurora. The thickest fog was over northwest
sections of the metro area such as around Boulder and Broomfield
where prevailing vsbys were still below 1/4 mile. Should see this
heavy fog erode from southeast-to-northwest over the next hour or
two as slightly drier air flows down off the Palmer Divide and
with mixing of the boundary layer with passing rain showers. Vort
lobe/shortwave trough rotating northward over the CWA during the
next couple of hours will enhance this shower activity as noted
in the previous discussion. Isolated t-storms also a possibility
towards midday. Hail, brief heavy rain and perhaps a funnel cloud
or two all possible with these cells. At this time, will make
only minor adjustments to the ongoing forecast. Will also hang
onto the winter weather and dense fog highlights for now.
&&
.SHORT TERM...(Today and tonight)
Issued at 402 AM MDT Mon May 16 2016
Pockets of dense fog have formed in the Denver and Boulder areas
with visibilities less than a quarter mile at times. Partial
clearing after last evening`s period of rain allowed for strong
radiational cooling along parts of the i-25 urban corridor.
Visibilities at KDEN have been less than a quarter mile since
about 2 AM MDT and a co-worker driving up Davidson Mesa outside of
Boulder reported visibilities less than 100 feet. Other
observations from local airports show visibilities greater than a
mile and a half. Have issued a dense fog advisory for zones 39 and
40 until 10 AM MDT to handle the morning rush hour.
Otherwise, the forecast remains on track. A band of showers has
been moving over western Colorado this morning with some embedded
thunderstorms as late at 3:30 AM MDT. These showers should
progress into the north central mountains in the next few hours
and then over northeast Colorado later today. The approaching
upper trough will place Colorado under rising motions through this
evening. The airmass is plenty moist and slightly unstable at mid-
levels which will allow for an extended period of precipitation
through this afternoon and evening. Temperatures in the mountains
are expected to cool through today with snow levels eventually
coming down to 10000 feet or lower. Significant accumulations will
be possible on the peaks, ridges and higher elevation roadways, so
a Winter Weather Advisory will be in effect through Tuesday.
Temperatures are going to be much cooler than normal due to the
lack of sunshine and occurring precipitation. Areas of
precipitation are expected to continue into the evening and then
diminish overnight.
.LONG TERM...(Tuesday through Sunday)
Issued at 402 AM MDT Mon May 16 2016
Models have an upper closed low over Nevada into western Colorado
at 12z Tuesday. The upper low weakens and falls apart as it moves
slowly eastward and across the CWA as an open trough through
Wednesday night. The flow aloft will weak all four periods. The
models keep weak qg upward vertical velocity for the CWA into
Wednesday night. Models have easterly low level flow for the CWA
Tuesday, then southeasterly well into Wednesday. Winds should be
close to normal diurnal drainage patterns Wednesday night. Models
show quite a bit of moisture over the CWA well into Wednesday
before decrease overnight. The qpf Fields show measurable
precipitation across all the CWA Tuesday into Tuesday evening.
There is very little measurable precipitation noted Wednesday and
Wednesday evening for the plains, but some in the mountains. There
is some CAPE mainly in the mountains and foothills late day
Tuesday and late day Wednesday. Lapse rates are not very steep,
especially over the plains both late days periods. will go with
30-60% pops on Tuesday and Tuesday evening. Late day Wednesday`s
pops are similar in the mountains and foothills only. The plains
can expected 10-20%s. for temperatures, Tuesday`s highs are 1-3 C
warmer than today`s expected highs. Wednesday`s readings warm up
2-5 c above Tuesday`s readings.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1215 PM MDT Mon May 16 2016
will hang onto ils cigs and vsbys at denver area terminals for
the remainder of the afternoon. may not see vsbys rising above 3
miles all day, even with passing showers and t-storms. ceilings
now not expected to rise above 1000 ft agl all day at KDEN, KAPA
and KBJC.
&&
.BOU Watches/Warnings/Advisories...
Winter Weather Advisory until noon MDT Tuesday for COZ031-033-
034.
&&
$$
UPDATE...Baker
SHORT TERM...Dankers
LONG TERM...RJK
AVIATION...Baker
Area Forecast Discussion
National Weather Service Grand Junction CO
1129 AM MDT MON MAY 16 2016
updated aviation section
.UPDATE...
Issued at 918 AM MDT Mon May 16 2016
Rain/Snow line is at about 8300 feet this morning, but will rise
throughout the day. Snow accumulation level on roads as of 9am
looks to be above 10,000 ft at the high passes, so have refrained
from issuing any advisories today with impacts minimal. Will keep
an eye on precipitation development, but expecting short lived
convective showers and thunderstorms this afternoon. Short term
forecast models indicate downturn in activity after sunset when
snow would accumulate on the roads again. Expecting the best
thunderstorms to develop across the Four Corners today with hail
the main threat.
&&
.SHORT TERM...(Today through Tuesday night)
Issued at 254 AM MDT Mon May 16 2016
Energy rotating around an upper level low located over southern
Idaho will continue to bring showers and thunderstorms to much of
eastern Utah and western Colorado through Tuesday.
First wave working through the area this morning with showers and
thunderstorms driving east into the central mountains. Snow levels
remain above 9k and bulk of activity has been light so far, so no
plans on hoisting any winter highlights for narrow stretches of
our high mountain passes. Could see a few inches accumulate above
10k by this evening, but road surfaces remain warm and impact
should be minimal. Otherwise, it`s looking like another unsettled
day with a few stronger storms again expected as moisture and
additional energy pass through. Wind gusts to 50 mph not out of
the question along with small hail. Models have remained
aggressive with pops and QPF values peaking during the afternoon
and evening hours. See no reason to stray far from that thinking
and pop grids will be geared this direction.
As the low drops or sags south into Utah, colder air will slide
south with it. This will lower snow levels a bit by Tuesday
morning, possibly as low as 8k, but levels rise throughout the day
back to near 10k by afternoon. Overall a very similar weather day
is expected with showers and thunderstorms throughout the region
and some accumulating snowfall for the highest peaks. Best shot at
more significant snowfall will push into the San Juans late
Tuesday and Tuesday night when we see another stronger wave rotate
out of the digging low with a period of favorable orographics and
dynamics coming into play. This will generate more persistent
precipitation that may eventually lead to more significant
snowfall accumulations from Telluride southeast to Wolf Creek
Pass. Main impacts would be overnight Tuesday into Wednesday
morning and later shifts can take a look at the need for any sort
of winter highlights.
Temperatures will be running on the cool side of normal through
mid-week and have undercut guidance values a bit today and again
on Tuesday due to cloud cover and showers.
.LONG TERM...(Wednesday through Sunday)
Issued at 254 AM MDT Mon May 16 2016
The upper level low will slowly fill over the southern Great Basin
by the end of the week with the cool and unsettled weather slowly
abating as we close out the week. The low fills on Wednesday with
remnants getting kicked out by late Thursday. This will lead to a
decrease in the showers and also send in some warmer air aloft
which lifts snow levels back up to near 10k by Wednesday
afternoon. Scattered activity then lingers through Thursday
afternoon, favoring the higher terrain.
By Friday, the Pacific Northwest gets a taste of what we`ve been
experiencing as a deep area of low pressure sets up just off the
coast and gets cutoff. This system barely moves from Thursday
through Sunday. The location of the low will cause a ridge to form
to our east pushing the trough to the plains and keeping us
`relatively` dry. Some afternoon convection can`t be ruled out as
ample moisture will remain while daytime heating will help to
destabilize the atmosphere. After the first half of the week
though, the weather will show a marked improvement.
Temperatures will slowly warming up through the weekend.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1129 AM MDT Mon May 16 2016
Stormy weather continues across the region through the end of the
week. Expect widespread showers and isolated thunderstorms through the
period with areas of IFR cigs possible, especially over the
higher elevations. Terminal sites may see periods of ILS cigs as
showers move through. Gusty outflow winds to 50 mph and small hail
will accompany the strongest storms and snow levels will be
running between 9 and 10k today, falling to as low as 8k tonight.
Mountain obscuration likely over the next 24 hours.
&&
.HYDROLOGY...
Issued at 918 AM MDT Mon May 16 2016
With the forecast wet weather and expected warming temperatures
toward the end of the week, river levels are expected to
gradually rise over the next few weeks. Flows will generally
increase due to snowpack melting with some streams reaching near
bankfull at times. Use caution in and near swift currents.
&&
.GJT Watches/Warnings/Advisories...
CO...None.
UT...None.
&&
$$
UPDATE...JAM
SHORT TERM...JDC
LONG TERM...TGR/JDC
AVIATION...TGJT
HYDROLOGY...JAM
Area Forecast Discussion
National Weather Service Grand Junction CO
918 AM MDT MON MAY 16 2016
.UPDATE...
Issued at 918 AM MDT Mon May 16 2016
Rain/Snow line is at about 8300 feet this morning, but will rise
throughout the day. Snow accumulation level on roads as of 9am
looks to be above 10,000 ft at the high passes, so have refrained
from issuing any advisories today with impacts minimal. Will keep
an eye on precipitation development, but expecting short lived
convective showers and thunderstorms this afternoon. Short term
forecast models indicate downturn in activity after sunset when
snow would accumulate on the roads again. Expecting the best
thunderstorms to develop across the Four Corners today with hail
the main threat.
&&
.SHORT TERM...(Today through Tuesday night)
Issued at 254 AM MDT Mon May 16 2016
Energy rotating around an upper level low located over southern
Idaho will continue to bring showers and thunderstorms to much of
eastern Utah and western Colorado through Tuesday.
First wave working through the area this morning with showers and
thunderstorms driving east into the central mountains. Snow levels
remain above 9k and bulk of activity has been light so far, so no
plans on hoisting any winter highlights for narrow stretches of
our high mountain passes. Could see a few inches accumulate above
10k by this evening, but road surfaces remain warm and impact
should be minimal. Otherwise, it`s looking like another unsettled
day with a few stronger storms again expected as moisture and
additional energy pass through. Wind gusts to 50 mph not out of
the question along with small hail. Models have remained
aggressive with pops and QPF values peaking during the afternoon
and evening hours. See no reason to stray far from that thinking
and pop grids will be geared this direction.
As the low drops or sags south into Utah, colder air will slide
south with it. This will lower snow levels a bit by Tuesday
morning, possibly as low as 8k, but levels rise throughout the day
back to near 10k by afternoon. Overall a very similar weather day
is expected with showers and thunderstorms throughout the region
and some accumulating snowfall for the highest peaks. Best shot at
more significant snowfall will push into the San Juans late
Tuesday and Tuesday night when we see another stronger wave rotate
out of the digging low with a period of favorable orographics and
dynamics coming into play. This will generate more persistent
precipitation that may eventually lead to more significant
snowfall accumulations from Telluride southeast to Wolf Creek
Pass. Main impacts would be overnight Tuesday into Wednesday
morning and later shifts can take a look at the need for any sort
of winter highlights.
Temperatures will be running on the cool side of normal through
mid-week and have undercut guidance values a bit today and again
on Tuesday due to cloud cover and showers.
.LONG TERM...(Wednesday through Sunday)
Issued at 254 AM MDT Mon May 16 2016
The upper level low will slowly fill over the southern Great Basin
by the end of the week with the cool and unsettled weather slowly
abating as we close out the week. The low fills on Wednesday with
remnants getting kicked out by late Thursday. This will lead to a
decrease in the showers and also send in some warmer air aloft
which lifts snow levels back up to near 10k by Wednesday
afternoon. Scattered activity then lingers through Thursday
afternoon, favoring the higher terrain.
By Friday, the Pacific Northwest gets a taste of what we`ve been
experiencing as a deep area of low pressure sets up just off the
coast and gets cutoff. This system barely moves from Thursday
through Sunday. The location of the low will cause a ridge to form
to our east pushing the trough to the plains and keeping us
`relatively` dry. Some afternoon convection can`t be ruled out as
ample moisture will remain while daytime heating will help to
destabilize the atmosphere. After the first half of the week
though, the weather will show a marked improvement.
Temperatures will slowly warming up through the weekend.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 254 AM MDT Mon May 16 2016
Unsettled weather will remain in the region through Tuesday.
Expect widespread showers and isolated thunderstorms through the
period with areas of IFR cigs possible, especially over the
higher elevations. Terminal sites may see periods of ILS cigs as
showers move through. Gusty outflow winds to 50 mph and small hail
will accompany the strongest storms and snow levels will be
running between 9 and 10k today, falling to as low as 8k tonight.
Mountain obscuration likely over the next 24 hours.
&&
.HYDROLOGY...
Issued at 918 AM MDT Mon May 16 2016
With the forecast wet weather and expected warming temperatures
toward the end of the week, river levels are expected to
gradually rise over the next few weeks. Flows will generally
increase due to snowpack melting with some streams reaching near
bankfull at times. Use caution in and near swift currents.
&&
.GJT Watches/Warnings/Advisories...
CO...None.
UT...None.
&&
$$
UPDATE...JAM
SHORT TERM...JDC
LONG TERM...TGR/JDC
AVIATION...JDC
HYDROLOGY...JAM
Area Forecast Discussion
National Weather Service Denver/Boulder CO
821 PM MDT SUN MAY 15 2016
.UPDATE...
Issued at 659 PM MDT Sun May 15 2016
The second band of showers today is now moving off the foothills.
some lightning persisted to near Jefferson County Airport...but
for the most part these showers are again weakening as they move
to the plains. This is part of a large band of clouds that extend
to the west slope...but satellite loops show a large dry slot
moving into southwest Colorado. The HRRR and RAP models both show
a dry period from around 06z to 13z for the metro area.
The surface pattern has been weak this evening...but a surface low
is forecast to develop near trinidad late tonight and intensify
tomorrow morning. This will result in increasing upslope flow
along the urban corridor and palmer divide...with showers
redeveloping Monday morning and continuing through the day.
Coordinated with adjoining offices on winter weather
advisory...and will issue one for the higher mountain passes
for late tonight through noon Tuesday. Models indicate that some
higher elevations may see up to 30 inches of snow by the time the
storm is done with us. It is likely to be a very wet sloppy mess
with daytime highs in the higher passes reaching 32 tomorrow.
All in all the previous forecast has a good handle on system
development...but mav guidance is 5 degrees colder than met
guidance. With the clouds...upslope...and moisture am going to
lower max temps in eastern Colorado on Monday and drop higher
passes a degree or two.
&&
.SHORT TERM...(This evening through Monday)
Issued at 322 PM MDT Sun May 15 2016
Initial shower band moving east on the plains but has mostly
dissipated. A larger batch of showers and thunderstorms over the
mountains will spread onto the plains this evening. This has more
forcing and since it is a large area of rain it will bring higher
dew points with it, so it should survive better. Still expecting a
bit of a break later tonight, but then the low on the east side of
the mountains will start to wind up. Some question about the
amount of low level moisture that persists through the night.
Models seem a bit overdone, so I am showing mostly cloudy skies
but not into the fog/drizzle regime yet, at least around Denver. During
the night the best moisture convergence will be across Wyoming and
the Nebraska panhandle, but this should all slide southward Monday
morning with the lower levels saturating, upslope winds, and
persistent lift. Some uncertainty about the timing of this
progressing from north to south but at this time it looks like
this will be happening during the morning hours. Generally
expecting light but steady rainfall, but with upslope enhancement
over the east slopes of the Front Range. Snow level should also be
lowering a bit during the day, settling somewhere around 7-8
thousand feet on the east slopes with warmer low levels holding it
higher on the west side. Could be some heavy snow in the
afternoon, but warm temps will limit the impact in populated areas
so just the highest roads are of concern.
.LONG TERM...(Monday night through Sunday)
Issued at 322 PM MDT Sun May 15 2016
Monday night...a broad closed upper low will stretch from
Northwest NV into northwest CO. Weak QG ascent will be over the
cwa overnight as this trough makes its way south into AZ by 00z
Wednesday. At the surface...a secondary surge will enhance the
upslope along the Front Range Monday night. The mdls show moderate
to strong QG ascent at the surface through the evening...with the
east to southeast upslope fm the surface to around 600 mb. NAM12
forecast sounding show moist adiabatic lapse rates with the
airmass saturated through the layer. There could be an isolated
tstm in the mountains Monday evening but it looks too stable
across the Urban Corridor and northeast plains with the possible
exception of the Palmer Divide. Overrunning type of setup Monday
night with the colder air below undercutting a fairly strong
inversion just above 700 mb. east and southeast facing aspects
above 9 thousand feet could receive 8 to 12 inches of snowfall by
tuesday morning...but not as much west of the Continental Divide.
No highlights yet but am learning more towards advisory type
snowfall vs warning at this time for the Front Range east of the
Continental Divide and possibly the higher foothills. The
foothills will see a accumulating snowfall above 8 thousand feet
with a steady mix of rain and snow down to 6500 feet. We could
possibly see a mix of rain/snow over the palmer divide above 6
thousand feet by tuesday morning. The mix of rain/snow in the
foothills should help alleviate any potential flooding risk as
well. Tuesday...a deep southeasterly upslope flow will be present
but the wind will not be as strong. Wl keep some light snow or
rain/snow mix in the mountains through the day...with higher pops
for light rain in and near the foothills/Palmer Divide as well. Wl
keep the mention of tstms in the grids but mainly over the
mountains. Tuesday night into Wednesday...the main area of
pcpn continues to get dragged to the south. There is still enough
moisture and some weak forcing around for showers...especially
over the mountain but the overall coverage will be decreasing.
The weakening trough finally shifts to the east of CO by Thu with
a drier and more subsident northwesterly flow aloft. An upper
level ridge will finally set up over the region late Thursday and
continue into Saturday. It will be much warmer by the weekend with
the more typical pattern of aftn/evng thunderstorms on Friday and
Saturday. The mdls continue to show a large upper trough over the
Pacific Northwest by the weekend...with an increasing southwesterly
flow aloft over CO by Sunday.
&&
.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 322 PM MDT Sun May 15 2016
The showers moving through the metro area will be followed by one
or two more bands of rain this evening...but it looks dry from 06z
until at least 13z. The winds have been the big question
today...other than the gusty winds with showers...it has been
difficult to pin down directions. This will become easier tomorrow
with the deepening upslope flow we will settle on north to
northeast winds for much of the day. Ceilings of 030 to 060 with
the showers will rise a bit overnight...then drop to mvfr monday
morning...with areas of ifr.
&&
.BOU Watches/Warnings/Advisories...winter weather advisory for
mountain zones...31...33...34 from 3am tonight to noon Tuesday.
&&
$$
UPDATE...RTG
SHORT TERM...Gimmestad
LONG TERM...Cooper
AVIATION...Gimmestad
AREA FORECAST DISCUSSION
National Weather Service New Orleans LA
310 PM CDT TUE MAY 17 2016
.SHORT TERM...
Active weather period continues across the forecast area. Radar
imagery over the last few hours shows quite a jump in intensity
along with coverage as daytime heating warmed the surface. Most of
the storms remain in the warm sector south of the stall frontal
boundary that was draped along a line from near Baton Rouge to
Hattiesburg. The GFS shows activity shifting south and east
through the rest of this afternoon as the very weak upper trough
that initialized the convection shifts east. The HRRR shows the
same depiction and this also matches up well with current radar
trends. So have increased pops over SELA and coastal MS through
the remainder of the afternoon and significantly dropped rain
chances for late this evening and overnight to slight chance as
little if any showers expected with drier mid level air moving in.
The main threat thru the afternoon will still be water spouts and
isolated tornadoes, mainly near the coastline. Although there`s
not a lot of strong wind in the mid and upper levels, there is
sufficient low level vertical and horizontal shear to potentially
see these hazards in the coastal waters and adjacent land areas.
Areas west of I-55 will not see much in the way of convection,
just a few showers.
.LONG TERM...
The lull in rain will carry over into Wednesday morning as there
will be not be as much lift from any upper level features to
enhance convection. However, daytime heating and possibly residual
frontal boundary could induce afternoon showers and storms. So, went
with 40 to 50% coverage during that period. Thursday does not look
all that different locally and thus kept the same or slightly higher
rain chances.
Friday still looks to be the most active day of the forecast period
as a more significant upper level trough tracks across the southern
plains and mid Mississippi Valley. Exactly when the widespread
showers begins in still not completely certain but current models
show something similar to yesterday with convection moving in from
the Gulf of Mexico/SW LA and spreading across the entire forecast
area. The widespread activity will likely last through Friday
afternoon and thus have carried likely pops through then. How much
rain is still uncertain at this time. The ECMWF shows maybe an inch
for most places. The GFS indicates a number much much higher than
that. Realistically thinking in the neighborhood of 1 to 4 inches
with isolated higher amounts. If this trend continues, flash flood
watch may be needed for Friday.
The upper level trough will amplify as it tracks east across the
United States Saturday and Sunday. Post trough cold front will usher
in drier air and likely keep the region rain free. So, have dropped
rain chances for those days. Some nice and slightly cooler mornings
will be possible as well.
MEFFER
&&
.AVIATION...
Scattered SHRA and TSRA this afternoon with most of the activity
east of Interstate 55 at this time. Most terminals with MVFR
ceilings this afternoon. Precipitation occasionally reducing
visibilities to 1SM. Expect most of the convection to weaken and/or
dissipate near sunset. May see some improvement to VFR conditions
during the evening hours, but should return to IFR/MVFR ceilings
around 09Z. Should see MVFR ceilings after 15z Wednesday...with
potential for scattered convection Wednesday afternoon. This will be
addressed in the 00Z TAF package. 35
&&
.MARINE...
Current marine issue is waterspout potential over the tidal lakes
and sounds. This should die out with convection this evening. Winds
should ease tonight with the departure of the upper impulse
currently moving across southern Mississippi and Louisiana. Will
allow Exercise Caution headline to expire...although it may be
borderline for another hour or two.
Should be a light wind regime until Thursday night when front
approaches from the northwest. Likely to need headlines at that time
over much of the coastal waters into Friday. Relatively quiet
conditions after Friday for the weekend. 35
&&
.DECISION SUPPORT...
DSS code: Blue.
Deployed: None.
Activation: None.
Activities: Monitoring convection.
Decision Support Services (DSS) Code Legend
Green = No weather impacts that require action.
Blue = Long-fused watch, warning, or advisory in effect or
high visibility event.
Yellow = Heightened impacts with short-fused watch, warning
or advisory issuances; radar support.
Orange = High Impacts; Slight to Moderate risk severe; nearby
tropical events; HazMat or other large episodes.
Red = Full engagement for Moderate risk of severe and/or
direct tropical threats; Events of National Significance.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 65 82 65 84 / 20 50 20 60
BTR 68 83 68 84 / 20 50 20 60
ASD 69 84 70 85 / 20 50 20 50
MSY 72 83 72 83 / 20 40 20 50
GPT 69 83 70 84 / 20 40 20 40
PQL 69 84 69 85 / 20 40 20 40
&&
.LIX Watches/Warnings/Advisories...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$