Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 07/01/16
Southeast Alaska Forecast Discussion...CORRECTED
National Weather Service Juneau AK
629 PM AKDT THU JUN 30 2016
.SHORT TERM...Leftover showers over the panhandle continue to
weaken through this afternoon. A low is approaching the southern
outer coast, bringing rain and small craft winds with it. The
transition from showers to rain will be hard to discern for more
southerly locations, but a brief break in precip farther north
will mark the end of one event and the beginning of the next.
Models have slowly been increasing the strength of this next low
and walking the forecast track further and further north. Morning
model update was sufficiently different to warrant a change to
pressures and winds for late tonight and tomorrow. Used the
Canadian NH model for these changes. Used a blend of official and
Canadian NH for updates to POP grids with little change to the
forecast. QPF increased via a blend of the RFC and Canadian REG.
3-hourly rainfall totals 0.22 inches or less, so no flooding
concerns from rainfall. The glacially dammed lake release near
Juneau is another issue, discussed below.
Updates to pressure increased winds over the coastal marine zones
and ocean entrances late tonight through tomorrow afternoon and
affect the area between Cape Decision to Kruzof Island mostly. Of
note, the easterly winds to 30 kt over coastal marine zone 41 were
maintained.
Overall forecast confidence is average.
.LONG TERM...The low discussed in the short term section will be
west of Sitka in the southern portion of marine zone 43 Friday
evening. As mentioned, latest models this morning deepened the
low quite a bit and shifted it north a bit faster. There will be a
band of 25kt winds near the low center and could have some gusts
of 35-40kt near ocean entrances. Some of the rainfall assoc with
this system will likely be moderate to heavy at times.
Another low looks to approach from the SW Saturday, but looks to
pass south of the area or through Dixon Entrance. This should in
turn cause a lower chance of precip across the northern panhandle,
but keep the far southern areas wet. Adjusted POPs down slightly
across the north as things become more isolated/scattered Sat
night. These may need to be lowered further if models continue
trending dryer, think that models are smoothing things out too
much and that precip will be intermittent/scattered and more dry
than wet...however mostly cloudy. Being 4-5 days out there is
still quite a bit of uncertainty with this portion of the forecast
and will be fine tuned with subsequent updates.
Used an ensemble approach to the forecast with an emphasis on the
Canadian NH model in the shorter term. Few adjustments were made
beyond this time frame due to uncertainty.
&&
.AVIATION...MVMC occasionally IMC conditions will prevail over the
southern half of the panhandle through the next 24 hours due to
both low CIGS and reduced VSBY in heavier bands of rain.
Conditions better to the north. Light chop below ridge tops
increasing from south to north due to low level 30-45kt jet
associated with the approaching low.
&&
.HYDROLOGY...Suicide Basin has released and a flood warning is in
effect for Mendenhall River and Lake. The current forecast crest
of 11.6 feet is close to the previous record value of 11.85 feet
set in 2014. As of early this afternoon, Mendenhall Lake had risen
to a stage of 6.5 feet and is rising very nearly as predicted. The
level in Suicide Basin has fallen 6 feet since early this morning
and continues to fall at around 1 foot per hour. Residents near
the lake or the river should remain alert and keep track of
updates to this event as they are issued by NWS Juneau.
&&
.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ012-036-041-042.
&&
$$
Fritsch/Ferrin
Visit us at http://www.weather.gov/Juneau
[top]
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
435 PM AKDT THU JUN 30 2016
.ANALYSIS AND UPPER LEVELS...
The upper levels are starting to look like a mixed bag of goodies. The ever
present upper level low spinning south of the gulf is slowly weakening but is
continuing to eject shortwaves around it. The first of these waves moved across
Southcentral last evening. The next is to the Northwest of PAYA and
is noted on upper level analysis as an enhanced bubble of moisture and
as a wiggle in the upper level analysis. This wave will move across
the ALCAN border and across the Copper River Basin this afternoon. As
of 2130z(1:30pm AKDT), showers are already beginning to form. This easterly
wave will wrap around the low and slide across the Anchorage and Kenai
areas tonight. A much more potent wave is easily identified in water
vapor imagery near 49N 141W. As is the case with nearly stationary lows
and these easterly waves that get ejected around, timing and placement
has been a challenge. This strong wave is now progged to shift east
and impact SE AK and BC. Farther west, a ridge between the Gulf low
and a weakening Bering low is becoming pinched off as it retreats into
the interior of Alaska. A strong upper level jet remains well south
of the forecast area. At the surface, progress is being made on moving
the nearly stationary low out of the gulf. A stalled out front stretches
from a low in the Bering and southeast across the Akpen.
&&
.MODEL DISCUSSION...
All models are in pretty good agreement in the short term today. As briefly
touched on in the analysis...the upper level low in the Gulf will shift
east into the weaken. All of the models have varying levels of agreement
with the shortwave strength and timing moving around the lows. The biggest
trend from yesterday was slowing down the timing of the onset of the
biggest rainmaker over Anchorage. The latest 18z runs of the NAM and
GFS are showing a 9-12z time frame while the HRRR is hinting at an early
start, between 5 and 6z. Judging by past performance of the HRRR and
how poorly the major models play temporally, confidence in timing is
low. However, all models are consistent with bringing in a healthy amount
of rain across the region.
&&
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Increasing mass ascent ahead of a low amplitude short wave trough
over the Western Yukon and Eastern Copper Basin is beginning to
manifest itself as increasing convective showers across the
region. As the shortwave propagates west tonight, showers will
begin to congeal into a large area of stratiform rain which will
impact all of Southcentral tonight with brief periods of heavy
rainfall. The heaviest axis of rain will likely occur across the
Copper Basin into the Mat-Su Valleys, although areas along the
Kenai and into Anchorage will also see the potential for brief
heavy rains overnight. Thunderstorms have formed already along the
Kenai Range, and they will also be possible along the Talkeetnas
and Alaska Range as well as along the Chugach in the evening. The
shortwave trough will elongate and quickly move west Friday, with
most rain moving into Southwest Alaska by the afternoon. Showers
will develop in the afternoon behind the main low, but these will
be mainly along mountains and rather limited given lack of
instability. Saturday will be warmer as broad cyclonic flow sets
up over the region, with more afternoon showers but slightly
warming temperatures.
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
The upper level low over the Gulf continues to bring easterly flow
with embedded shortwaves over Southwest Alaska. This combined
with the unstable environment is helping to kick off thunderstorms
over the area through Friday. The most likely times for thunderstorms
are during peak heating and as the shortwaves move through. The
shortwaves look to move through this evening, Friday morning and
Friday evening. Friday will also see heavier rain from the
Kuskokwim Valley south towards Bristol Bay and east towards the
Alaska and Aleutian Ranges. Saturday will see a lesser chance for
thunderstorms with the most likely area over the Kuskokwim Vally
but rain will still be likely from the valley through Bristol Bay.
&&
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A broad low over the Western Aleutians will last through the
weekend slowly tracking east and bringing rain to the area. Areas
from the Alaska Peninsula through the Pribilof Islands will be
under the effects of weak ridging providing more fair conditions
than areas to the west.
&&
.LONG TERM FORECAST (Days 3 through 7)...
The extended forecast beginning this weekend will start off with
two lows, one weakening over the Western Bering, and the other
weakening over the Gulf of Alaska Saturday afternoon. Easterly
shortwave troughs rotating around the Gulf low will be supporting
rain across parts of Southern Alaska, some possibly heavy at
times. The first of these waves will track through the Southwest
Mainland while weakening Saturday, and quickly push southward over
the Alaska Peninsula by Sunday morning. The second, and weaker wave
will pivot through Southcentral Saturday and into the Kenai
Peninsula by Sunday morning. Forecast confidence remains lower,
as the model solutions continue to struggle with the timing and
positioning of these waves rotating around the parent Gulf low.
Either way, diurnally driven showers are expected over parts of
the southern mainland into the middle of next week, as the Gulf
low begins to track further eastward. The warmest temperatures
will likely be west of the Alaska Range with moderate temps across
Southcentral. By early next week, weak ridging is expected to
build in behind the departing Gulf low with continued inland
showers driven by diurnal heating.
&&
.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.
&&
$$
SYNOPSIS AND MODEL DISCUSSION...SS
SOUTHCENTRAL ALASKA...JA
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...TP
AREA FORECAST DISCUSSION
National Weather Service BILLINGS MT
812 PM MDT THU JUN 30 2016
.UPDATE...
Made a few tweaks to the forecast this evening to up the PoPs
across the western and central zones for the next few hours.
Outflow from activity earlier this afternoon has helped to
generate some precipitation from Musselshell to Sweet Grass
County. None of these storms are particularly strong and should
not amount to anything other than dropping some much needed
precipitation across the area. Time Lagged HRRR Ensemble model did
a very good job of predicting this line of activity, and has it
moving into Billings between 3 and 4 UTC. Singer
&&
.SHORT TERM...valid for Fri and Sat...
Water vapor imagery shows a ridge over the high plains with weak
energy emerging from the northern great basin and a stronger
shortwave well to our north in northwest MT into Alberta. Shear is
weaker than the past few days but diurnal destabilization and weak
forcing is allowing convection mainly over our mtns to this point,
though at 21z there was some activity developing on a boundary in
southern Yellowstone County close to Billings. Expect an overall
increase in activity over the next few hours across our west and
central parts. Eastern areas are drier/stable now but will see
chances increase later tonight into Friday as shortwave moves
across the area. Convection should remain non-severe in our cwa
but could see a few stronger storms with small hail and enhanced
downdraft winds.
One note of interest: Billings needs 0.02" of rain this evening to
avoid its driest June on record.
On Friday, greatest chance of storms will be in our east along
plume of higher theta-e air as southeasterly flow continues in
this area. Pwats to an inch support locally heavy rain but weak
forcing and shear should keep storms below severe levels once
again. To our west, upper ridging will limit amount of convection
but a few weak storms are possible with diurnal heating. This
activity will diminish Friday night.
Temps Friday will be a few degrees warmer than today with highs
in the mid 80s to lower 90s.
JKL
.LONG TERM...valid for Sun...Mon...Tue...Wed...Thu...
Saturday, upper level energy slides in over western Montana
increasing rain chances Saturday and Sunday afternoons. Saturday
appears to be the warmest of the days this weekend with highs
solidly in the mid 90s across the Plains. In the wake of this
disturbance passing, southwesterly flow will prevail aloft. Best
rain chances will be confined to higher terrain through mid week
until the next system arrives. If the current model trends
continue Wed/Thur will be a better period to see more widespread
showers and thunderstorms across the area. Walsh
&&
.AVIATION...
A few isolated showers with embedded thunderstorms can be expected near KBIL
this evening. Short range models have precipitation moving into
the Billings area between 3 and 4 UTC. Otherwise, VFR conditions
should prevail for the rest of the night at all terminals. Singer
&&
.PRELIMINARY POINT TEMP/POPS...
Fri Sat Sun Mon Tue Wed Thu
-----------------------------------------------------------
BIL 060/091 062/095 062/093 061/090 060/089 059/087 057/088
42/T 22/T 32/T 31/B 12/T 22/T 22/T
LVM 051/090 052/093 053/088 051/087 049/085 048/084 047/084
42/T 22/T 22/T 32/T 22/T 22/T 22/T
HDN 058/091 059/095 060/093 059/092 057/091 056/088 056/089
42/T 22/T 22/T 31/B 11/B 12/T 22/T
MLS 062/089 063/094 064/093 062/092 062/090 060/088 059/088
22/T 22/T 32/T 22/W 22/T 23/T 32/T
4BQ 061/087 060/094 063/095 062/093 062/093 060/091 058/090
24/T 22/T 22/T 22/W 11/B 11/B 22/T
BHK 056/082 057/089 060/091 060/091 059/089 058/086 056/086
23/T 22/T 22/T 22/W 22/T 23/T 33/T
SHR 056/088 054/092 056/092 055/090 055/091 054/089 054/089
32/T 22/T 22/T 21/B 11/B 11/B 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Southcentral and Southwest Alaska Forecast Discussion...CORRECTED
National Weather Service Anchorage AK
1108 PM AKDT THU JUN 30 2016
Corrected extended discussion
.ANALYSIS AND UPPER LEVELS...
The upper levels are starting to look like a mixed bag of goodies. The ever
present upper level low spinning south of the gulf is slowly weakening but is
continuing to eject shortwaves around it. The first of these waves moved across
Southcentral last evening. The next is to the Northwest of PAYA and
is noted on upper level analysis as an enhanced bubble of moisture and
as a wiggle in the upper level analysis. This wave will move across
the ALCAN border and across the Copper River Basin this afternoon. As
of 2130z(1:30pm AKDT), showers are already beginning to form. This easterly
wave will wrap around the low and slide across the Anchorage and Kenai
areas tonight. A much more potent wave is easily identified in water
vapor imagery near 49N 141W. As is the case with nearly stationary lows
and these easterly waves that get ejected around, timing and placement
has been a challenge. This strong wave is now progged to shift east
and impact SE AK and BC. Farther west, a ridge between the Gulf low
and a weakening Bering low is becoming pinched off as it retreats into
the interior of Alaska. A strong upper level jet remains well south
of the forecast area. At the surface, progress is being made on moving
the nearly stationary low out of the gulf. A stalled out front stretches
from a low in the Bering and southeast across the Akpen.
&&
.MODEL DISCUSSION...
All models are in pretty good agreement in the short term today. As briefly
touched on in the analysis...the upper level low in the Gulf will shift
east into the weaken. All of the models have varying levels of agreement
with the shortwave strength and timing moving around the lows. The biggest
trend from yesterday was slowing down the timing of the onset of the
biggest rainmaker over Anchorage. The latest 18z runs of the NAM and
GFS are showing a 9-12z time frame while the HRRR is hinting at an early
start, between 5 and 6z. Judging by past performance of the HRRR and
how poorly the major models play temporally, confidence in timing is
low. However, all models are consistent with bringing in a healthy amount
of rain across the region.
&&
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Increasing mass ascent ahead of a low amplitude short wave trough
over the Western Yukon and Eastern Copper Basin is beginning to
manifest itself as increasing convective showers across the
region. As the shortwave propagates west tonight, showers will
begin to congeal into a large area of stratiform rain which will
impact all of Southcentral tonight with brief periods of heavy
rainfall. The heaviest axis of rain will likely occur across the
Copper Basin into the Mat-Su Valleys, although areas along the
Kenai and into Anchorage will also see the potential for brief
heavy rains overnight. Thunderstorms have formed already along the
Kenai Range, and they will also be possible along the Talkeetnas
and Alaska Range as well as along the Chugach in the evening. The
shortwave trough will elongate and quickly move west Friday, with
most rain moving into Southwest Alaska by the afternoon. Showers
will develop in the afternoon behind the main low, but these will
be mainly along mountains and rather limited given lack of
instability. Saturday will be warmer as broad cyclonic flow sets
up over the region, with more afternoon showers but slightly
warming temperatures.
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
The upper level low over the Gulf continues to bring easterly flow
with embedded shortwaves over Southwest Alaska. This combined
with the unstable environment is helping to kick off thunderstorms
over the area through Friday. The most likely times for thunderstorms
are during peak heating and as the shortwaves move through. The
shortwaves look to move through this evening, Friday morning and
Friday evening. Friday will also see heavier rain from the
Kuskokwim Valley south towards Bristol Bay and east towards the
Alaska and Aleutian Ranges. Saturday will see a lesser chance for
thunderstorms with the most likely area over the Kuskokwim Vally
but rain will still be likely from the valley through Bristol Bay.
&&
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A broad low over the Western Aleutians will last through the
weekend slowly tracking east and bringing rain to the area. Areas
from the Alaska Peninsula through the Pribilof Islands will be
under the effects of weak ridging providing more fair conditions
than areas to the west.
&&
.LONG TERM FORECAST (Days 3 through 7)...
On Sunday, the upper level pattern looks to grind to a halt from
the easterly flow of weak disturbances to a much more chaotic
movement. This will be due to the departure of the upper level low
towards the Panhandle by Sunday morning, with no larger scale
features following it. Thus, with everything being weak, any
precipitation that develops Sunday over southern mainland Alaska
will be scattered and weak. The persistence of a mid-level
unstable layer over much of the area will result in some
convection popping up with any showers that develop with enhanced
lift, likely from topographic enhancement.
For the Independence Day holiday, a strong upper level trough will
dig southward across the eastern Bering. Ridging will build east
of it across the Gulf. However, the models are in disagreement
with how quickly the ridge builds, and where the trough axis sets
up over the Bering. Currently, the models agree enough for the
4th of July to suggest a return to southwesterly winds in the
upper levels. Since the disturbances depicted in the models all
remain weak, the weather looks similar to Sunday at this point for
much of mainland Alaska.
Active weather should persist for much of southern Alaska into
midweek as the trough over the Bering moves into mainland Alaska.
However, the model differences and associated forecast
uncertainty only compound with time concerning how quickly and in
what form (open trough or cutoff low), the troughing moves east.
&&
.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.
&&
$$
SYNOPSIS AND MODEL DISCUSSION...SS
SOUTHCENTRAL ALASKA...JA
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...JW
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
533 AM AKDT FRI JUL 1 2016
.SHORT TERM...The biggest story over the next 24 hours is the
ongoing glacial dam release from Suicide Basin into Mendenhall
Lake and River. This will be covered further in the hydrology
section below.
As for the weather, the main feature is a 1000 mb low pressure
system currently in the southeast gulf which will gradually weaken
while moving north to near Cape Fairweather by late tonight. A
secondary wave of low pressure will develop southwest of Haida
Gwaii late tonight but is expected to remain south of the area.
Stratiform rainfall is currently ongoing across the southern half
of the panhandle aided by warm air advection in association with
the advancing low. This will continue to spread northward through
the day reaching the Juneau area this morning and the far northern
panhandle this afternoon. Precipitation chances will remain high
throughout the next 24 hours across all of Southeast Alaska.
Expecting rainfall totals to generally range from one half of an
inch to an inch with heaviest amounts over the southern panhandle.
This system will enhance winds over the southern half of the area
but am only expecting 10 to 20 mph for the land areas and 20-25 kt
for the inner channels. Decreased winds across the far northern
panhandle as a parallel pressure gradient to Northern Lynn Canal
will lead to lighter winds.
Used the 06z NAM and Hi-Res model guidance for updates to the
short term period. Forecaster confidence is above average.
.LONG TERM...Through the weekend, generally a zonal flow pattern
in place across the north Pacific aloft. The closed low at 500 mb
over the Gulf of Alaska weakens and moves into western Canada
Monday while a broad weak ridge aloft forms over the western gulf.
Weak to null flow aloft over the northern panhandle will be in
place headed into early next week. Long range trend for Southeast
Alaska looks to be for a development around mid week to the end of
the week over the gulf.
A surface low near Cape Fairweather is weakening, while a low
moving across the southern gulf along 50N and then curving north
across Haida Gwaii on Saturday. This will spread rain into the
southern half of the panhandle. Saturday evening the low will move
into British Columbia while the low off of Cross Sound dissipates.
The surface pattern across the gulf Friday into Saturday becomes
west to northwest. The potential for low probability showers from
onshore flow will exist along the outer coast Sunday into Monday.
With the main flow pattern to the south of the forecast area not
expecting a significant weather system for the next few days.
&&
.HYDROLOGY...Suicide Basin has released and a flood warning is in
effect for Mendenhall River and Lake until Saturday morning. The
current forecast crest of 11.6 feet is close to the previous
record value of 11.85 feet set in 2014. As of early this morning,
Mendenhall Lake had risen to a stage of 8.5 feet and the rate of
rise is steadily increasing as expected. The level in Suicide
Basin continues to fall rapidly. Residents near the lake or the
river should remain alert and keep track of updates to this event
as they are issued by NWS Juneau.
&&
.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ033>036-041>043.
&&
$$
TPS/Bezenek
Visit us at http://www.weather.gov/Juneau
[top]
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
447 AM AKDT FRI JUL 1 2016
.ANALYSIS AND UPPER LEVELS...
Upper level lows are over the western Bering and the southern Gulf
of Ak this morning with the jet remaining well south of the
forecast area. At the surface, lows are near Attu and over the
eastern Gulf. A ridge of high pressure is over the eastern Bering.
The thermal trough/theta-e ridge is draped along the Alaska and
Aleutian ranges and is serving as the focus for showers and even
a few nocturnal thunderstorms.
&&
.MODEL DISCUSSION...
Models remain in agreement that the Gulf upper low will slowly
rotate its way into British Columbia by Sun morning. Easterly
waves moving along the northern flank of the low will interact
with the moisture rich thermal trough/theta-e ridge through the
weekend. This may explain what is happening, but these waves are
poorly timed in model solutions, so exactly when precipitation
initiation and enhancement will occur remains a problem. The
forecast utilizes some Nam and GFS in an attempt to pinpoint some
of the precipitation events.
In the west the surface low will drift and weaken over the western
Aleutians through the weekend. A weak associated front will move
to the central Aleutians during the same period. Again the Nam and
GFS were utilized in the forecast.
&&
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
The last of a series of fairly strong short-waves crossing
westward across Southcentral Alaska this morning will exit to
Southwest Alaska this afternoon bringing an end to widespread
showers and rain. However, as the large upper low over the Gulf
tracks eastward today and tonight, short-waves tracking across
Southwest Alaska will rotate southeastward across Kodiak Island
and the western Gulf bringing widespread showers to that region.
In the wake of the upper level low the flow across the region will
become more and more chaotic, with weak impulses wandering around.
This creates a lot of uncertainty in the forecast. Have used a
broadbrush approach to the precip forecast for tonight through
Saturday night. In this scenario would expect more showers during
the afternoon and evening hours focused along the mountains.
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Clouds, rain, and thunderstorms will be the focus for Friday and
Saturday. Widespread showers with embedded thunderstorms will
encompass the Kuskokwim Valley southward through Greater Bristol
Bay today. A lesser chance exists over the Kuskokwim Delta, but
afternoon showers and a slight chance for thunder are possible.
Nearly the same conditions are on tap for Saturday, however, any
thunderstorms will stay confined to the Kuskokwim Valley along
the Alaska Range. For the Delta, most of the shower activity will
be east of Bethel along the Kilbucks. Winds will be on the lighter
side everywhere, and temperatures will be well above average for
this time of year.
Technically speaking...A large upper level low in the gulf
controls the pattern, but the real action is rotating around the
circulation in the form of embedded easterly shortwaves. Feeding
on the baroclinity from the difference between the cooler gulf
airmass and the warmer Interior/Yukon airmass, these waves amplify
and provide the forcing for diurnally enhanced showers and
thunderstorms. Ridging over the northern portion of the state is
breeding warm low level temperatures that will be advected down
into the Southwest Mainland, as well as some juicy dewpoints by
Alaska standards. These conditions are ripe for frequent lightning
over mainly the Kuskokwim Valley and into Bristol Bay today. The
upper level energy lingers through the weekend keeping at least
showers in the forecast.
&&
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A weakening system aloft over the Western Bering will bring rain
today from Shemya through the Central Aleutians, and as far east
as the Eastern Aleutians. That system will weaken through the
weekend and not produce meaningful precipitation after today. A
fairly narrow corridor of dense fog will set up today roughly from
Saint Matthew through the Pribilofs and linger through tonight.
&&
.LONG TERM FORECAST (Days 3 through 7)...
On Sunday, the upper level pattern looks to grind to a halt from
the easterly flow of weak disturbances to a much more chaotic
movement. This will be due to the departure of the upper level low
towards the Panhandle by Sunday morning, with no larger scale
features following it. Thus, with everything being weak, any
precipitation that develops Sunday over southern mainland Alaska
will be scattered and weak. The persistence of a mid-level
unstable layer over much of the area will result in some
convection popping up with any showers that develop with enhanced
lift, likely from topographic enhancement.
For the Independence Day holiday, a strong upper level trough will
dig southward across the eastern Bering. Ridging will build east
of it across the Gulf. However, the models are in disagreement
with how quickly the ridge builds, and where the trough axis sets
up over the Bering. Currently, the models agree enough for the
4th of July to suggest a return to southwesterly winds in the
upper levels. Since the disturbances depicted in the models all
remain weak, the weather looks similar to Sunday at this point for
much of mainland Alaska.
Active weather should persist for much of southern Alaska into
midweek as the trough over the Bering moves into mainland Alaska.
However, the model differences and associated forecast
uncertainty only compound with time concerning how quickly and in
what form (open trough or cutoff low), the troughing moves east.
&&
.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.
&&
$$
SYNOPSIS AND MODEL DISCUSSION...DS
SOUTHCENTRAL ALASKA...SEB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML
LONG TERM...JW
[top]
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
418 AM AKDT FRI JUL 1 2016
.DISCUSSION...
UPPER AIR...
A high pressure ridge currently extends from the Chukotsk
Peninsula eastward across the Brooks Range into northwestern
Canada, with a high center near the Bering Strait. The ridge
will gradually transition to a high pressure center which will
be pushed gradually eastward through Sunday night as a strong
short wave drops southward out of the Russian Arctic Ocean. By
late Sunday night the upper level high will be centered near
Fort Yukon, with the strong short wave trough extending along
178W across the Chukchi Sea and Bering Sea.
A series of weak short wave troughs will move westward across the
southern interior through Saturday. A weak short wave trough is
now moving westward across the central interior. The next short
wave trough is now over the southern Yukon Territory and will
move to the Alcan border by Friday morning then fracture into
two troughs. The southern piece of the trough will continue to
move westward and gradually deepen over the lower Kuskokwim Valley
and southeastward Friday evening. The northern piece of the trough
will stall out over the eastern interior Friday night and
gradually weaken Saturday.
SURFACE...
A 1007 mb low centered near Northway will deepen to a 1001 mb
low about 100 miles east of Northway by this afternoon, then
remain nearly stationary through Saturday. A weak thermal
trough will develop across the northern interior Saturday.
INTERIOR...
Areas or bands of showers and thunderstorms associated with the
short wave troughs aloft will move westward across the southern
interior and the Alaska Range, otherwise there will be isolated
to scattered showers and isolated thunderstorms over most areas
through the weekend. The heaviest rainfall today will likely be
over Denali and the lower Kuskokwim Valley. The heaviest rainfall
amounts tonight are expect to be in the lower Kuskokwim valley and
in nearby area of the middle Yukon Valley. More showers and
isolated thunderstorms are expected over much of the interior
Saturday, and over much of the southern and eastern interior
Sunday.
ARCTIC SLOPE AND BROOKS RANGE...
Areas of fog near the coast during the late night and
early morning hours, otherwise no significant weather
expected through Sunday. Warm temperatures in the interior with
highs as high as the low to mid 70s.
WEST COAST...
No significant weather expected through Sunday. Some
coastal areas may see areas of fog.
Coastal Hazard Potential Days 3 and 4...None.
&&
.FIRE WEATHER...
Some warming is expected in the interior over the weekend...with
highs approaching or reaching 80 in some northern interior areas.
Minimum humidities could approach 30 percent in the northern
interior. Minimum humidities in the southern interior likely to
remain at 35 percent or above.
&&
.HYDROLOGY...
Additional rainfall amounts of 0.5 to 1 inch are expected
in Denali and the lower Kuskokwim Valley today. Northern parts of
the Upper Tanana Valley and Fortymile country may see up to 0.5
inch, with local amounts of 0.75 inch possible. Locally heavier
amounts will be possible in Denali and the lower Kuskokwim Valley
today, but the location of the amounts remains uncertain due to
the convective nature of the precipitation.
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
Small craft advisory for PKZ245.
&&
$$
RF JUN 16
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
418 AM AKDT FRI JUL 1 2016
.DISCUSSION...
UPPER AIR...
A high pressure ridge currently extends from the Chukotsk
Peninsula eastward across the Brooks Range into northwestern
Canada, with a high center near the Bering Strait. The ridge
will gradually transition to a high pressure center which will
be pushed gradually eastward through Sunday night as a strong
short wave drops southward out of the Russian Arctic Ocean. By
late Sunday night the upper level high will be centered near
Fort Yukon, with the strong short wave trough extending along
178W across the Chukchi Sea and Bering Sea.
A series of weak short wave troughs will move westward across the
southern interior through Saturday. A weak short wave trough is
now moving westward across the central interior. The next short
wave trough is now over the southern Yukon Territory and will
move to the Alcan border by Friday morning then fracture into
two troughs. The southern piece of the trough will continue to
move westward and gradually deepen over the lower Kuskokwim Valley
and southeastward Friday evening. The northern piece of the trough
will stall out over the eastern interior Friday night and
gradually weaken Saturday.
SURFACE...
A 1007 mb low centered near Northway will deepen to a 1001 mb
low about 100 miles east of Northway by this afternoon, then
remain nearly stationary through Saturday. A weak thermal
trough will develop across the northern interior Saturday.
INTERIOR...
Areas or bands of showers and thunderstorms associated with the
short wave troughs aloft will move westward across the southern
interior and the Alaska Range, otherwise there will be isolated
to scattered showers and isolated thunderstorms over most areas
through the weekend. The heaviest rainfall today will likely be
over Denali and the lower Kuskokwim Valley. The heaviest rainfall
amounts tonight are expect to be in the lower Kuskokwim valley and
in nearby area of the middle Yukon Valley. More showers and
isolated thunderstorms are expected over much of the interior
Saturday, and over much of the southern and eastern interior
Sunday.
ARCTIC SLOPE AND BROOKS RANGE...
Areas of fog near the coast during the late night and
early morning hours, otherwise no significant weather
expected through Sunday. Warm temperatures in the interior with
highs as high as the low to mid 70s.
WEST COAST...
No significant weather expected through Sunday. Some
coastal areas may see areas of fog.
Coastal Hazard Potential Days 3 and 4...None.
&&
.FIRE WEATHER...
Some warming is expected in the interior over the weekend...with
highs approaching or reaching 80 in some northern interior areas.
Minimum humidities could approach 30 percent in the northern
interior. Minimum humidities in the southern interior likely to
remain at 35 percent or above.
&&
.HYDROLOGY...
Additional rainfall amounts of 0.5 to 1 inch are expected
in Denali and the lower Kuskokwim Valley today. Northern parts of
the Upper Tanana Valley and Fortymile country may see up to 0.5
inch, with local amounts of 0.75 inch possible. Locally heavier
amounts will be possible in Denali and the lower Kuskokwim Valley
today, but the location of the amounts remains uncertain due to
the convective nature of the precipitation.
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
Small craft advisory for PKZ245.
&&
$$
RF JUN 16
Southcentral and Southwest Alaska Forecast Discussion...CORRECTED
National Weather Service Anchorage AK
1108 PM AKDT THU JUN 30 2016
Corrected extended discussion
.ANALYSIS AND UPPER LEVELS...
The upper levels are starting to look like a mixed bag of goodies. The ever
present upper level low spinning south of the gulf is slowly weakening but is
continuing to eject shortwaves around it. The first of these waves moved across
Southcentral last evening. The next is to the Northwest of PAYA and
is noted on upper level analysis as an enhanced bubble of moisture and
as a wiggle in the upper level analysis. This wave will move across
the ALCAN border and across the Copper River Basin this afternoon. As
of 2130z(1:30pm AKDT), showers are already beginning to form. This easterly
wave will wrap around the low and slide across the Anchorage and Kenai
areas tonight. A much more potent wave is easily identified in water
vapor imagery near 49N 141W. As is the case with nearly stationary lows
and these easterly waves that get ejected around, timing and placement
has been a challenge. This strong wave is now progged to shift east
and impact SE AK and BC. Farther west, a ridge between the Gulf low
and a weakening Bering low is becoming pinched off as it retreats into
the interior of Alaska. A strong upper level jet remains well south
of the forecast area. At the surface, progress is being made on moving
the nearly stationary low out of the gulf. A stalled out front stretches
from a low in the Bering and southeast across the Akpen.
&&
.MODEL DISCUSSION...
All models are in pretty good agreement in the short term today. As briefly
touched on in the analysis...the upper level low in the Gulf will shift
east into the weaken. All of the models have varying levels of agreement
with the shortwave strength and timing moving around the lows. The biggest
trend from yesterday was slowing down the timing of the onset of the
biggest rainmaker over Anchorage. The latest 18z runs of the NAM and
GFS are showing a 9-12z time frame while the HRRR is hinting at an early
start, between 5 and 6z. Judging by past performance of the HRRR and
how poorly the major models play temporally, confidence in timing is
low. However, all models are consistent with bringing in a healthy amount
of rain across the region.
&&
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Increasing mass ascent ahead of a low amplitude short wave trough
over the Western Yukon and Eastern Copper Basin is beginning to
manifest itself as increasing convective showers across the
region. As the shortwave propagates west tonight, showers will
begin to congeal into a large area of stratiform rain which will
impact all of Southcentral tonight with brief periods of heavy
rainfall. The heaviest axis of rain will likely occur across the
Copper Basin into the Mat-Su Valleys, although areas along the
Kenai and into Anchorage will also see the potential for brief
heavy rains overnight. Thunderstorms have formed already along the
Kenai Range, and they will also be possible along the Talkeetnas
and Alaska Range as well as along the Chugach in the evening. The
shortwave trough will elongate and quickly move west Friday, with
most rain moving into Southwest Alaska by the afternoon. Showers
will develop in the afternoon behind the main low, but these will
be mainly along mountains and rather limited given lack of
instability. Saturday will be warmer as broad cyclonic flow sets
up over the region, with more afternoon showers but slightly
warming temperatures.
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
The upper level low over the Gulf continues to bring easterly flow
with embedded shortwaves over Southwest Alaska. This combined
with the unstable environment is helping to kick off thunderstorms
over the area through Friday. The most likely times for thunderstorms
are during peak heating and as the shortwaves move through. The
shortwaves look to move through this evening, Friday morning and
Friday evening. Friday will also see heavier rain from the
Kuskokwim Valley south towards Bristol Bay and east towards the
Alaska and Aleutian Ranges. Saturday will see a lesser chance for
thunderstorms with the most likely area over the Kuskokwim Vally
but rain will still be likely from the valley through Bristol Bay.
&&
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A broad low over the Western Aleutians will last through the
weekend slowly tracking east and bringing rain to the area. Areas
from the Alaska Peninsula through the Pribilof Islands will be
under the effects of weak ridging providing more fair conditions
than areas to the west.
&&
.LONG TERM FORECAST (Days 3 through 7)...
On Sunday, the upper level pattern looks to grind to a halt from
the easterly flow of weak disturbances to a much more chaotic
movement. This will be due to the departure of the upper level low
towards the Panhandle by Sunday morning, with no larger scale
features following it. Thus, with everything being weak, any
precipitation that develops Sunday over southern mainland Alaska
will be scattered and weak. The persistence of a mid-level
unstable layer over much of the area will result in some
convection popping up with any showers that develop with enhanced
lift, likely from topographic enhancement.
For the Independence Day holiday, a strong upper level trough will
dig southward across the eastern Bering. Ridging will build east
of it across the Gulf. However, the models are in disagreement
with how quickly the ridge builds, and where the trough axis sets
up over the Bering. Currently, the models agree enough for the
4th of July to suggest a return to southwesterly winds in the
upper levels. Since the disturbances depicted in the models all
remain weak, the weather looks similar to Sunday at this point for
much of mainland Alaska.
Active weather should persist for much of southern Alaska into
midweek as the trough over the Bering moves into mainland Alaska.
However, the model differences and associated forecast
uncertainty only compound with time concerning how quickly and in
what form (open trough or cutoff low), the troughing moves east.
&&
.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.
&&
$$
SYNOPSIS AND MODEL DISCUSSION...SS
SOUTHCENTRAL ALASKA...JA
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...JW
AREA FORECAST DISCUSSION
National Weather Service San Diego CA
350 AM PDT FRI JUL 1 2016
.SYNOPSIS...
Southwestern California will remain on the western edge of mid
level monsoonal moisture today with widely scattered thunderstorms
expected for the mountains and upper deserts for this afternoon.
Drying aloft will follow for this weekend through next week as a
trough of low pressure develops near the West Coast. High
temperatures will remain near average. The marine layer and
onshore flow will bring areas of night and morning low clouds and
fog from the coast into portions of the valleys.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
Early this morning...a thunderstorm complex was over northeastern
San Bernardino County and far southern Nevada with an outflow
boundary moving southward across San Bernardino County.
Mid level moisture remains centered around 600 mb...with higher
resolution models showing the development of widely scattered
thunderstorms this afternoon near the mountain ridge tops and
along the desert mountain slopes and in the upper deserts...mainly
along and east of interstate 15.
A developing trough of low pressure near the West Coast will
bring drier southwest flow aloft for the weekend into next week
with near seasonal high temperatures. The marine layer and weak
onshore flow will keep coastal areas cooler with areas of night
and morning coastal low clouds and fog extending into portions of
the valleys. Higher resolution models show the marine layer
becoming deep enough for stratus to extend into the far inland
valleys Saturday morning...then becoming gradually shallower
through next week.
&&
.AVIATION...
Coast/Valleys...BKN-OVC stratus 25-30 miles inland will continue
this morning, with clearing in the valleys between 16-18z, and
partial clearing at the coast 18-20z. Bases will be 1000-1700 ft MSL
with tops to 2500 ft MSL. Areas of vis 3-5 mi will occur in the
valleys this morning with local vis below 1 mi vcnty KRNM, KF70 and
KRIV. Confidence of forecast is moderately high.
Mountains/Deserts...Mostly clear skies with unrestricted VIS will
prevail this morning, then areas of SCT-BKN cu/tcu will develop this
afternoon with bases 9000 ft MSL. Isolated thunderstorms mainly
mountaintop based with tops to 45000 ft MSL possible. Sfc wind gusts
to 40 kt possible near any stronger storms. Chance of t-storms
diminishes rapidly by sunset.
&&
.MARINE...
No hazardous marine weather is expected through Tuesday.
&&
.BEACHES...
Latest nearshore buoy reports continue to show a 5-6 ft/18 second
swell from 200 degrees, and swell was mostly 4-6 feet on southwest
facing beaches earlier Thursday. Swell should very gradually lower
later today and through the weekend, though strong dangerous rip
currents will continue through this evening. Most of the surf will
be 5 feet or less by Saturday, though strong rip currents will still
be possible, which could cause issues due to large beach crowds
expected over the holiday weekend. The Beach Hazards Statement
remains in effect through this evening, and may be extended later
today.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX Watches/Warnings/Advisories...
CA...Beach Hazards Statement through this evening for Orange County
Coastal Areas-San Diego County Coastal Areas.
PZ...None.
&&
$$
PUBLIC...17
AVIATION/MARINE/BEACHES...JMB
[top]
Area Forecast Discussion
National Weather Service Sacramento CA
334 AM PDT FRI JUL 1 2016
.SYNOPSIS...
Hot and mainly dry this week. A slight cooling trend starting
this weekend and continuing through the week. Isolated late day
thunderstorms possible over the Sierra Friday and Saturday.
&&
.DISCUSSION...
Water vapor and RAP model 500 mb analysis showed plenty of dry air
with an area of upper level divergence associated with a weak
upper level trough positioned over NorCal overnight. A lack of a
delta influenced breeze has kept temperatures overnight ranging
between the low to mid 70s for much of the valley...with the
northern end of the Sacramento valley in the lower 80s as of 3 am
PDT.
Plenty of sunshine and warm temperatures will continue today
across the forecast area. Smoke from the Trailhead fire near Todd
Valley could bring some haze and patchy smoke today for
surrounding communities. Temperatures in the valley will range
from the upper 90s in the southern Sacramento Valley and Northern
San Joaquin Valley, but temperatures will reach triple digits
again in the northern Sacramento Valley. Higher elevations will
see 70s and 80s today. The latest high resolution model runs have
some showers and thunderstorms developing in the Sierra Nevada
mountains during the afternoon hours, but the placement should be
to the east of the crest. As a result, there are some slight
chances for thunderstorms at the higher elevations mentioned in
the forecast.
Chances for thunderstorms will continue Saturday afternoon for the
Sierra Nevada mountains south of US Highway 50. High temperatures
will continue to be 5 to 10 degrees above normal for the valley. A
shortwave trough moving across the Pacific northwest will bring
slightly cooler temperatures to the valley for Sunday and Monday
with highs in the lower to mid 90s, and dry weather is
anticipated due to a lack of moisture and instability across the
forecast area.
&&
.EXTENDED DISCUSSION (Tuesday THROUGH Friday)
A weak upper trough will persist over the Pacific Northwest into
extreme NorCal next week, resulting in dry weather and near normal
temperatures. Onshore, southwest winds may be breezy over higher
terrain with our typical Delta Breeze impacting the valley.
Expect high temperatures in the 90s across the Valley, with 70s
and 80s over the mountains. JClapp/JBB
&&
.AVIATION...
VFR conditions the next 24 hours. Winds will generally be around
10 kts or less. Winds in northern Sacramento valley for KRDD and
KRBL will switch from northerly this morning to southeasterly in
the afternoon. Otherwise, onshore flow expected for the rest of
the valley/TAF sites. Delta Breeze will increase again this
afternoon and evening. Areas of smoke near the Trailhead fire.
JBB
&&
.STO Watches/Warnings/Advisories...
None.
&&
$$
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
303 PM AKDT FRI JUL 1 2016
.SYNOPSIS...
Aloft...
A ridge stretching east to west across northern Alaska will
persist through the weekend then retreat east in NW Canada next
week as a trough develops over the Bering Sea. A low aloft in the
Gulf of Alaska will move over SE Alaska Sat and then move slowly
east. A series of short wave troughs rotating around this low will
move west across Interior Alaska bringing bands of showers and
isolated to scattered thunderstorms to the eastern and southern
Interior through the weekend.
A strong short wave that now lies from Denali to Livengood to Old
Crow will move to McGrath to Tanana to Arctic Village by 4am
Sat...and then weaken in place through Sun. There is a wide band
of showers NW of this trough that becomes scattered north of the
Yukon River. This dropped .10 to .25 inch of rain over the eastern
Interior south of Circle with up to .50 inch in the hills north of
Fox and east of Delta Junction. Expect this to drop another .50 to
1 inch over zones 221 225 and 227 through Sat with the heaviest
amounts in Denali Park. From .50-1.5 inch of rain has already
fallen in Denali Park so this will keep small stream and rivers
there high through the weekend and could still cause mud and rock
slides.
A second and weaker short wave trough near Old Crow will move to
Fort Yukon by 4am Sat...to Denali to Livengood by 4pm Sat...and
then slowly dissipate through Sun. This will cause scattered
showers and scattered PM thunderstorms in eastern zone 216
western 221 and 227 Sat and into Sun. The thunderstorms could
have small hail Sat.
A third short wave trough over the southern Yukon Territory will
move to the ALCAN Border by 4pm Sat and then weaken over the
eastern Interior through Sun. This will bring more widespread
showers to zones 224 226 Sat into Sun and keep scattered showers
and at least isolated thunderstorms going in the remainder of the
eastern Interior. There is the potential for hail again Sun and
this will need to be watched.
A fourth short wave is expected to move to the extreme SE interior
Sun night and Mon and could bring heavy rain...but this still has
a lot of uncertainty.
Surface...
An Arctic warm front from Barter Island to Deadhorse will move to
Barter Island north by 4am Sat then move north of the coast.
Expect fog to reform along this front tonight and then move
offshore Sat.
A 1022 mb high over the central Bering Sea will weaken slowly
through Sun.
An Arctic cold front in the western Chukchi Sea will move east to
Barrow to Cape Lisburne then west by 4pm Sat...to Deadhorse to a
1007 mb low near Point Hope by 4am Sun...and then quasi-
stationary. Fog and a chance of rain will accompany the front.
Westerly flow will increase south of the low center and should
return widespread fog to the southern Chukchi and north Bering
Seas and most of the West Coast of AK by Sat night.
&&
.DISCUSSION...
Models are similar on the large scale flow pattern and features
but differ some on timing and location of weak short wave troughs
moving west across the Interior. Since these weak short wave
troughs are the main force driving convection over the interior
the location is important. We favor the GFS locations of the short
waves and heavy rain through Sat night Sun and then the flow
becomes so weak that we can really only deal with short wave
location and accompanying rainfall in a probabilistic sense.
Coastal Hazard Potential Days 3 and 4...None.
&&
.FIRE WEATHER...
Continued wet across southern and eastern Interior with drier and
warmer conditions in the northwest Interior. Expect isolated
thunderstorms a a few lightning strikes today and Sat...except LAL
3 Sat in eastern Zone 216...western 221 and 227. Sun could see LAL
3 over the eastern Interior but uncertain at this point so left it
as LAL 2 for Sun.
&&
.HYDROLOGY...
The past 36 hrs saw .10 to .25 inch of rain fall over the eastern
Interior south of Circle with up to .50 inch in the hills north of
Fox and hills east of Delta Junction...while Denali Park had
between .50-1.5 inch. Expect another .50 to 1 inch over zones 221
225 and 227 through Sat with the heaviest amounts in Denali Park.
This will keep small stream and rivers in Denali high through the
weekend and could cause mud and rock slides through the weekend.
There is a potential for heavy rain in zones 224 and 226 SE of
Tok Sun night and Mon but still much uncertainty on this.
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory for PKZ245.
&&
$$
JB JUL 16
[top]
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
533 AM AKDT FRI JUL 1 2016
.SHORT TERM...The biggest story over the next 24 hours is the
ongoing glacial dam release from Suicide Basin into Mendenhall
Lake and River. This will be covered further in the hydrology
section below.
As for the weather, the main feature is a 1000 mb low pressure
system currently in the southeast gulf which will gradually weaken
while moving north to near Cape Fairweather by late tonight. A
secondary wave of low pressure will develop southwest of Haida
Gwaii late tonight but is expected to remain south of the area.
Stratiform rainfall is currently ongoing across the southern half
of the panhandle aided by warm air advection in association with
the advancing low. This will continue to spread northward through
the day reaching the Juneau area this morning and the far northern
panhandle this afternoon. Precipitation chances will remain high
throughout the next 24 hours across all of Southeast Alaska.
Expecting rainfall totals to generally range from one half of an
inch to an inch with heaviest amounts over the southern panhandle.
This system will enhance winds over the southern half of the area
but am only expecting 10 to 20 mph for the land areas and 20-25 kt
for the inner channels. Decreased winds across the far northern
panhandle as a parallel pressure gradient to Northern Lynn Canal
will lead to lighter winds.
Used the 06z NAM and Hi-Res model guidance for updates to the
short term period. Forecaster confidence is above average.
.LONG TERM...Through the weekend, generally a zonal flow pattern
in place across the north Pacific aloft. The closed low at 500 mb
over the Gulf of Alaska weakens and moves into western Canada
Monday while a broad weak ridge aloft forms over the western gulf.
Weak to null flow aloft over the northern panhandle will be in
place headed into early next week. Long range trend for Southeast
Alaska looks to be for a development around mid week to the end of
the week over the gulf.
A surface low near Cape Fairweather is weakening, while a low
moving across the southern gulf along 50N and then curving north
across Haida Gwaii on Saturday. This will spread rain into the
southern half of the panhandle. Saturday evening the low will move
into British Columbia while the low off of Cross Sound dissipates.
The surface pattern across the gulf Friday into Saturday becomes
west to northwest. The potential for low probability showers from
onshore flow will exist along the outer coast Sunday into Monday.
With the main flow pattern to the south of the forecast area not
expecting a significant weather system for the next few days.
&&
.HYDROLOGY...Suicide Basin has released and a flood warning is in
effect for Mendenhall River and Lake until Saturday morning. The
current forecast crest of 11.6 feet is close to the previous
record value of 11.85 feet set in 2014. As of early this morning,
Mendenhall Lake had risen to a stage of 8.5 feet and the rate of
rise is steadily increasing as expected. The level in Suicide
Basin continues to fall rapidly. Residents near the lake or the
river should remain alert and keep track of updates to this event
as they are issued by NWS Juneau.
&&
.AJK Watches/Warnings/Advisories...
PUBLIC...None.
MARINE...Small Craft Advisory for PKZ033>036-041>043.
&&
$$
TPS/Bezenek
Visit us at http://www.weather.gov/Juneau
[top]
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
447 AM AKDT FRI JUL 1 2016
.ANALYSIS AND UPPER LEVELS...
Upper level lows are over the western Bering and the southern Gulf
of Ak this morning with the jet remaining well south of the
forecast area. At the surface, lows are near Attu and over the
eastern Gulf. A ridge of high pressure is over the eastern Bering.
The thermal trough/theta-e ridge is draped along the Alaska and
Aleutian ranges and is serving as the focus for showers and even
a few nocturnal thunderstorms.
&&
.MODEL DISCUSSION...
Models remain in agreement that the Gulf upper low will slowly
rotate its way into British Columbia by Sun morning. Easterly
waves moving along the northern flank of the low will interact
with the moisture rich thermal trough/theta-e ridge through the
weekend. This may explain what is happening, but these waves are
poorly timed in model solutions, so exactly when precipitation
initiation and enhancement will occur remains a problem. The
forecast utilizes some Nam and GFS in an attempt to pinpoint some
of the precipitation events.
In the west the surface low will drift and weaken over the western
Aleutians through the weekend. A weak associated front will move
to the central Aleutians during the same period. Again the Nam and
GFS were utilized in the forecast.
&&
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
The last of a series of fairly strong short-waves crossing
westward across Southcentral Alaska this morning will exit to
Southwest Alaska this afternoon bringing an end to widespread
showers and rain. However, as the large upper low over the Gulf
tracks eastward today and tonight, short-waves tracking across
Southwest Alaska will rotate southeastward across Kodiak Island
and the western Gulf bringing widespread showers to that region.
In the wake of the upper level low the flow across the region will
become more and more chaotic, with weak impulses wandering around.
This creates a lot of uncertainty in the forecast. Have used a
broadbrush approach to the precip forecast for tonight through
Saturday night. In this scenario would expect more showers during
the afternoon and evening hours focused along the mountains.
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Clouds, rain, and thunderstorms will be the focus for Friday and
Saturday. Widespread showers with embedded thunderstorms will
encompass the Kuskokwim Valley southward through Greater Bristol
Bay today. A lesser chance exists over the Kuskokwim Delta, but
afternoon showers and a slight chance for thunder are possible.
Nearly the same conditions are on tap for Saturday, however, any
thunderstorms will stay confined to the Kuskokwim Valley along
the Alaska Range. For the Delta, most of the shower activity will
be east of Bethel along the Kilbucks. Winds will be on the lighter
side everywhere, and temperatures will be well above average for
this time of year.
Technically speaking...A large upper level low in the gulf
controls the pattern, but the real action is rotating around the
circulation in the form of embedded easterly shortwaves. Feeding
on the baroclinity from the difference between the cooler gulf
airmass and the warmer Interior/Yukon airmass, these waves amplify
and provide the forcing for diurnally enhanced showers and
thunderstorms. Ridging over the northern portion of the state is
breeding warm low level temperatures that will be advected down
into the Southwest Mainland, as well as some juicy dewpoints by
Alaska standards. These conditions are ripe for frequent lightning
over mainly the Kuskokwim Valley and into Bristol Bay today. The
upper level energy lingers through the weekend keeping at least
showers in the forecast.
&&
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A weakening system aloft over the Western Bering will bring rain
today from Shemya through the Central Aleutians, and as far east
as the Eastern Aleutians. That system will weaken through the
weekend and not produce meaningful precipitation after today. A
fairly narrow corridor of dense fog will set up today roughly from
Saint Matthew through the Pribilofs and linger through tonight.
&&
.LONG TERM FORECAST (Days 3 through 7)...
On Sunday, the upper level pattern looks to grind to a halt from
the easterly flow of weak disturbances to a much more chaotic
movement. This will be due to the departure of the upper level low
towards the Panhandle by Sunday morning, with no larger scale
features following it. Thus, with everything being weak, any
precipitation that develops Sunday over southern mainland Alaska
will be scattered and weak. The persistence of a mid-level
unstable layer over much of the area will result in some
convection popping up with any showers that develop with enhanced
lift, likely from topographic enhancement.
For the Independence Day holiday, a strong upper level trough will
dig southward across the eastern Bering. Ridging will build east
of it across the Gulf. However, the models are in disagreement
with how quickly the ridge builds, and where the trough axis sets
up over the Bering. Currently, the models agree enough for the
4th of July to suggest a return to southwesterly winds in the
upper levels. Since the disturbances depicted in the models all
remain weak, the weather looks similar to Sunday at this point for
much of mainland Alaska.
Active weather should persist for much of southern Alaska into
midweek as the trough over the Bering moves into mainland Alaska.
However, the model differences and associated forecast
uncertainty only compound with time concerning how quickly and in
what form (open trough or cutoff low), the troughing moves east.
&&
.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.
&&
$$
SYNOPSIS AND MODEL DISCUSSION...DS
SOUTHCENTRAL ALASKA...SEB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML
LONG TERM...JW
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
418 AM AKDT FRI JUL 1 2016
.DISCUSSION...
UPPER AIR...
A high pressure ridge currently extends from the Chukotsk
Peninsula eastward across the Brooks Range into northwestern
Canada, with a high center near the Bering Strait. The ridge
will gradually transition to a high pressure center which will
be pushed gradually eastward through Sunday night as a strong
short wave drops southward out of the Russian Arctic Ocean. By
late Sunday night the upper level high will be centered near
Fort Yukon, with the strong short wave trough extending along
178W across the Chukchi Sea and Bering Sea.
A series of weak short wave troughs will move westward across the
southern interior through Saturday. A weak short wave trough is
now moving westward across the central interior. The next short
wave trough is now over the southern Yukon Territory and will
move to the Alcan border by Friday morning then fracture into
two troughs. The southern piece of the trough will continue to
move westward and gradually deepen over the lower Kuskokwim Valley
and southeastward Friday evening. The northern piece of the trough
will stall out over the eastern interior Friday night and
gradually weaken Saturday.
SURFACE...
A 1007 mb low centered near Northway will deepen to a 1001 mb
low about 100 miles east of Northway by this afternoon, then
remain nearly stationary through Saturday. A weak thermal
trough will develop across the northern interior Saturday.
INTERIOR...
Areas or bands of showers and thunderstorms associated with the
short wave troughs aloft will move westward across the southern
interior and the Alaska Range, otherwise there will be isolated
to scattered showers and isolated thunderstorms over most areas
through the weekend. The heaviest rainfall today will likely be
over Denali and the lower Kuskokwim Valley. The heaviest rainfall
amounts tonight are expect to be in the lower Kuskokwim valley and
in nearby area of the middle Yukon Valley. More showers and
isolated thunderstorms are expected over much of the interior
Saturday, and over much of the southern and eastern interior
Sunday.
ARCTIC SLOPE AND BROOKS RANGE...
Areas of fog near the coast during the late night and
early morning hours, otherwise no significant weather
expected through Sunday. Warm temperatures in the interior with
highs as high as the low to mid 70s.
WEST COAST...
No significant weather expected through Sunday. Some
coastal areas may see areas of fog.
Coastal Hazard Potential Days 3 and 4...None.
&&
.FIRE WEATHER...
Some warming is expected in the interior over the weekend...with
highs approaching or reaching 80 in some northern interior areas.
Minimum humidities could approach 30 percent in the northern
interior. Minimum humidities in the southern interior likely to
remain at 35 percent or above.
&&
.HYDROLOGY...
Additional rainfall amounts of 0.5 to 1 inch are expected
in Denali and the lower Kuskokwim Valley today. Northern parts of
the Upper Tanana Valley and Fortymile country may see up to 0.5
inch, with local amounts of 0.75 inch possible. Locally heavier
amounts will be possible in Denali and the lower Kuskokwim Valley
today, but the location of the amounts remains uncertain due to
the convective nature of the precipitation.
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
Small craft advisory for PKZ245.
&&
$$
RF JUN 16
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
418 AM AKDT FRI JUL 1 2016
.DISCUSSION...
UPPER AIR...
A high pressure ridge currently extends from the Chukotsk
Peninsula eastward across the Brooks Range into northwestern
Canada, with a high center near the Bering Strait. The ridge
will gradually transition to a high pressure center which will
be pushed gradually eastward through Sunday night as a strong
short wave drops southward out of the Russian Arctic Ocean. By
late Sunday night the upper level high will be centered near
Fort Yukon, with the strong short wave trough extending along
178W across the Chukchi Sea and Bering Sea.
A series of weak short wave troughs will move westward across the
southern interior through Saturday. A weak short wave trough is
now moving westward across the central interior. The next short
wave trough is now over the southern Yukon Territory and will
move to the Alcan border by Friday morning then fracture into
two troughs. The southern piece of the trough will continue to
move westward and gradually deepen over the lower Kuskokwim Valley
and southeastward Friday evening. The northern piece of the trough
will stall out over the eastern interior Friday night and
gradually weaken Saturday.
SURFACE...
A 1007 mb low centered near Northway will deepen to a 1001 mb
low about 100 miles east of Northway by this afternoon, then
remain nearly stationary through Saturday. A weak thermal
trough will develop across the northern interior Saturday.
INTERIOR...
Areas or bands of showers and thunderstorms associated with the
short wave troughs aloft will move westward across the southern
interior and the Alaska Range, otherwise there will be isolated
to scattered showers and isolated thunderstorms over most areas
through the weekend. The heaviest rainfall today will likely be
over Denali and the lower Kuskokwim Valley. The heaviest rainfall
amounts tonight are expect to be in the lower Kuskokwim valley and
in nearby area of the middle Yukon Valley. More showers and
isolated thunderstorms are expected over much of the interior
Saturday, and over much of the southern and eastern interior
Sunday.
ARCTIC SLOPE AND BROOKS RANGE...
Areas of fog near the coast during the late night and
early morning hours, otherwise no significant weather
expected through Sunday. Warm temperatures in the interior with
highs as high as the low to mid 70s.
WEST COAST...
No significant weather expected through Sunday. Some
coastal areas may see areas of fog.
Coastal Hazard Potential Days 3 and 4...None.
&&
.FIRE WEATHER...
Some warming is expected in the interior over the weekend...with
highs approaching or reaching 80 in some northern interior areas.
Minimum humidities could approach 30 percent in the northern
interior. Minimum humidities in the southern interior likely to
remain at 35 percent or above.
&&
.HYDROLOGY...
Additional rainfall amounts of 0.5 to 1 inch are expected
in Denali and the lower Kuskokwim Valley today. Northern parts of
the Upper Tanana Valley and Fortymile country may see up to 0.5
inch, with local amounts of 0.75 inch possible. Locally heavier
amounts will be possible in Denali and the lower Kuskokwim Valley
today, but the location of the amounts remains uncertain due to
the convective nature of the precipitation.
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
Small craft advisory for PKZ245.
&&
$$
RF JUN 16
Southcentral and Southwest Alaska Forecast Discussion...CORRECTED
National Weather Service Anchorage AK
1108 PM AKDT THU JUN 30 2016
Corrected extended discussion
.ANALYSIS AND UPPER LEVELS...
The upper levels are starting to look like a mixed bag of goodies. The ever
present upper level low spinning south of the gulf is slowly weakening but is
continuing to eject shortwaves around it. The first of these waves moved across
Southcentral last evening. The next is to the Northwest of PAYA and
is noted on upper level analysis as an enhanced bubble of moisture and
as a wiggle in the upper level analysis. This wave will move across
the ALCAN border and across the Copper River Basin this afternoon. As
of 2130z(1:30pm AKDT), showers are already beginning to form. This easterly
wave will wrap around the low and slide across the Anchorage and Kenai
areas tonight. A much more potent wave is easily identified in water
vapor imagery near 49N 141W. As is the case with nearly stationary lows
and these easterly waves that get ejected around, timing and placement
has been a challenge. This strong wave is now progged to shift east
and impact SE AK and BC. Farther west, a ridge between the Gulf low
and a weakening Bering low is becoming pinched off as it retreats into
the interior of Alaska. A strong upper level jet remains well south
of the forecast area. At the surface, progress is being made on moving
the nearly stationary low out of the gulf. A stalled out front stretches
from a low in the Bering and southeast across the Akpen.
&&
.MODEL DISCUSSION...
All models are in pretty good agreement in the short term today. As briefly
touched on in the analysis...the upper level low in the Gulf will shift
east into the weaken. All of the models have varying levels of agreement
with the shortwave strength and timing moving around the lows. The biggest
trend from yesterday was slowing down the timing of the onset of the
biggest rainmaker over Anchorage. The latest 18z runs of the NAM and
GFS are showing a 9-12z time frame while the HRRR is hinting at an early
start, between 5 and 6z. Judging by past performance of the HRRR and
how poorly the major models play temporally, confidence in timing is
low. However, all models are consistent with bringing in a healthy amount
of rain across the region.
&&
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Increasing mass ascent ahead of a low amplitude short wave trough
over the Western Yukon and Eastern Copper Basin is beginning to
manifest itself as increasing convective showers across the
region. As the shortwave propagates west tonight, showers will
begin to congeal into a large area of stratiform rain which will
impact all of Southcentral tonight with brief periods of heavy
rainfall. The heaviest axis of rain will likely occur across the
Copper Basin into the Mat-Su Valleys, although areas along the
Kenai and into Anchorage will also see the potential for brief
heavy rains overnight. Thunderstorms have formed already along the
Kenai Range, and they will also be possible along the Talkeetnas
and Alaska Range as well as along the Chugach in the evening. The
shortwave trough will elongate and quickly move west Friday, with
most rain moving into Southwest Alaska by the afternoon. Showers
will develop in the afternoon behind the main low, but these will
be mainly along mountains and rather limited given lack of
instability. Saturday will be warmer as broad cyclonic flow sets
up over the region, with more afternoon showers but slightly
warming temperatures.
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
The upper level low over the Gulf continues to bring easterly flow
with embedded shortwaves over Southwest Alaska. This combined
with the unstable environment is helping to kick off thunderstorms
over the area through Friday. The most likely times for thunderstorms
are during peak heating and as the shortwaves move through. The
shortwaves look to move through this evening, Friday morning and
Friday evening. Friday will also see heavier rain from the
Kuskokwim Valley south towards Bristol Bay and east towards the
Alaska and Aleutian Ranges. Saturday will see a lesser chance for
thunderstorms with the most likely area over the Kuskokwim Vally
but rain will still be likely from the valley through Bristol Bay.
&&
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A broad low over the Western Aleutians will last through the
weekend slowly tracking east and bringing rain to the area. Areas
from the Alaska Peninsula through the Pribilof Islands will be
under the effects of weak ridging providing more fair conditions
than areas to the west.
&&
.LONG TERM FORECAST (Days 3 through 7)...
On Sunday, the upper level pattern looks to grind to a halt from
the easterly flow of weak disturbances to a much more chaotic
movement. This will be due to the departure of the upper level low
towards the Panhandle by Sunday morning, with no larger scale
features following it. Thus, with everything being weak, any
precipitation that develops Sunday over southern mainland Alaska
will be scattered and weak. The persistence of a mid-level
unstable layer over much of the area will result in some
convection popping up with any showers that develop with enhanced
lift, likely from topographic enhancement.
For the Independence Day holiday, a strong upper level trough will
dig southward across the eastern Bering. Ridging will build east
of it across the Gulf. However, the models are in disagreement
with how quickly the ridge builds, and where the trough axis sets
up over the Bering. Currently, the models agree enough for the
4th of July to suggest a return to southwesterly winds in the
upper levels. Since the disturbances depicted in the models all
remain weak, the weather looks similar to Sunday at this point for
much of mainland Alaska.
Active weather should persist for much of southern Alaska into
midweek as the trough over the Bering moves into mainland Alaska.
However, the model differences and associated forecast
uncertainty only compound with time concerning how quickly and in
what form (open trough or cutoff low), the troughing moves east.
&&
.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.
&&
$$
SYNOPSIS AND MODEL DISCUSSION...SS
SOUTHCENTRAL ALASKA...JA
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...JW
AREA FORECAST DISCUSSION
National Weather Service San Diego CA
144 PM PDT FRI JUL 1 2016
.SYNOPSIS...
Monsoonal moisture and instability aloft will continue the
possibility of scattered showers and thunderstorms over portions
of the mountains and deserts through this evening. A low pressure
trough along the west coast will lower high temperatures to normal
or below seasonal normals, create breezy southwesterly winds in
the mountains and deserts, a moderate to deep marine layer and dry
weather Saturday through next Thursday.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
At 1 PM PDT, water vapor imagery displayed an upper-level ridge
over Texas, and an upper-level trough over Northern California.
Visible satellite showed low clouds along the coast, and cumulus
over mountain peaks. Composite radar showed a thunderstorm just
southeast of Big Bear, and a thunderstorm south of Barstow. A 12
C marine layer inversion on the 01/1200 UTC KNKX sounding will
make it difficult for areas along the beach and over the waters to
clear today. Most unstable CAPE of 500-1000 J/KG, precipitable
water of 1.1-1.3 inches and diurnal heating will combine to
continue a chance of thunderstorms over the mountains and deserts
through early evening. Heavy downpours, urban and small stream
flooding, gusty winds and frequent lightning are possible where
storms develop. Isolated flash flooding is possible where
stationary storms develop.
The aforementioned trough will linger along the West Coast this
weekend into the middle of next week. This will help lower high
temperatures to near normal to slightly below normal today through
the middle of next week. Dry SW flow aloft will eliminate chances
for afternoon thunderstorms tomorrow through next Thursday. A deep
marine layer will push night/morning low clouds and fog far into
the valleys tonight. The marine layer will become slightly more
shallow through next week, limiting the extent of the clouds and
fog into the valleys each night. Breezy southwesterly winds will
develop each afternoon through mountain passes and over the
deserts.
&&
.AVIATION...
012017Z...Coast/Valleys...Through 02/0000 UTC, mostly SKC and
unrestricted vis, except within 3-5 SM of the coast where BKN-OVC
clouds 1300-2300 ft MSL will likely linger. 02/0000-1500 UTC,
stratus re-developing 20-25 SM inland and perhaps up to 25-40 SM
inland with bases 1100-1800 ft MSL and tops around 2500 ft MSL.
Areas of 3-5 SM vis over inland mesas. Local vis AOB 1 SM possible
over far inland valleys, such as KRNM and KRIV. Forecast confidence
of stratus occurrence and timing at KSAN, KCRQ and KSNA is high,
with low-to-moderate confidence for KONT and low confidence on
exactly how far inland the stratus will spread.
Mountains/Deserts...Isol-sct thunderstorms/showers in the mountains,
high deserts and possibly lower deserts through 02/0300 UTC with SCT-
BKN cloud bases around 10000 ft MSL, tops around 20000 ft MSL and CB
tops to 40000 ft MSL. Otherwise, mostly SKC and unrestricted vis
will prevail through Saturday morning.
&&
.MARINE...
No hazardous marine weather is expected through Tuesday.
&&
.BEACHES...
Latest nearshore buoy reports show a 4-5 ft/17 second swell from 200
degrees. Surfline shows 4-7 foot surf in Orange County and 3-5 foot
surf in San Diego county being reported today. Surf around these
heights, with locally higher sets, should continue this afternoon,
along with strong rip currents. Although the swell and surf will
gradually lower Saturday through Independence Day, with large beach
crowds expected and rip currents still likely a concern, hazardous
swimming conditions are likely to continue. The Beach Hazards
Statement has been extended through Mon July 4.
&&
.SKYWARN...
Skywarn activation is requested for San Bernardino County.
Although activation is not requested for Riverside, San Diego or
Orange counties at this time, weather spotters are encouraged to
report significant weather conditions as they occur.
&&
.SGX Watches/Warnings/Advisories...
CA...Beach Hazards Statement through Monday evening for Orange County
Coastal Areas-San Diego County Coastal Areas.
PZ...None.
&&
$$
PUBLIC...JJT
AVIATION/MARINE/BEACHES...Harrison
[top]
Area Forecast Discussion
National Weather Service Phoenix AZ
145 PM MST FRI JUL 1 2016
&&
.SYNOPSIS...
A combination of lingering monsoon moisture and weak weather
disturbances moving eastward across the desert southwest will bring
chances for showers and thunderstorms tonight across sw and south-
central Arizona, and on Saturday, over the higher terrain of eastern
Arizona. A return to drier southwest flow aloft will begin to take
over starting Saturday and end any rain chances starting Sunday.
High temperatures will steadily climb into the weekend and early
next week as the atmosphere becomes drier. The dry and warm
conditions will likely last through much of next week.
&&
.DISCUSSION...
.late this afternoon/tonight....
A bit of a break in action across our cwa this hour, with the shower
and thunderstorm activity that affected parts of South-Central AZ
this morning having moved well off to the south and east, now
extending northward from eastern Pima/Cochise counties to eastern
Gila County. The shower activity this morning is currently holding
down temperatures a bit over South-Central AZ, with Phoenix Sky
Harbor airport only up to 90 degrees at noon, under clear skies.
Further to the west, over western Maricopa and La Paz/Yuma counties,
fields of CU can be seen developing on latest visible satellite
imagery, over areas that stayed dry this morning, allowing
temperatures to rise well up into the 90s at midday. Surface
dewpoints remain elevated at most lower desert locations, well up
into the 60s to near 70. Up to the north, new thunderstorms can be
seen on radar developing over Yavapai County.
As far as the forecast for this afternoon/evening is concerned, in
spite of normally unfavorable westerly flow that is developing over
the region as an upper trof approaches the CA coast, the combination
of lingering low-level moisture and another shortwave approaching
from the northwest will likely produce another round of convective
activity across South-Central and SW AZ later this
afternoon/evening. Today`s situation appears to be more like a
transition event rather then a classic monsoon case, with the GFS
forecast soundings showing 1500-2000 J/KG of CAPE (with little or no
CIN), and 25-30 knots of bulk shear over the region through this
evening. The 12Z WRFGFS, which did a good job with this morning`s
convective activity, is showing shower/thunderstorm development
later this afternoon across northern La Paz and NW Maricopa
Counties, with this activity moving into the Greater Phoenix area
this evening as the shortwave trigger moves eastward across northern
AZ. Given all this available convective energy and intrusion of
drier air above 600mb, a few of the storms could become severe, with
very strong downburst winds, heavy downpours, localized flooding,
and even small hail possible. Thus, have raised POPS this evening
well up into the chance range across the lower deserts of South-
Central AZ, and into the likely range over southern Gila County.
.Saturday through next Friday...
This weekend will bring a continued drying westerly flow, but enough
lingering low level moisture should exist for some isolated eastern
Arizona high terrain afternoon showers and thunderstorms. The
possibility of any activity over the lower deserts is pretty slim
due to the westerly steering flow and PWATS dropping down to around
1.25 inches. By Sunday, enough dry air should be in place for there
to be little chance of any storms even over the high terrain.
Temperatures this weekend will be on the upswing with the drier
conditions and clear to mostly clear skies as highs climb back toward
normal readings.
Next week looks to be mostly quiet as far as any storm potential as
the upper high center generally stays to our southeast providing us
with westerly or southwesterly flow. Temperatures should peak by
Tuesday or Wednesday with some lower desert spots reaching 110F for
highs. 500mb heights do climb to around 592dm and 850mb temperatures
near 30C, but at this point it does not appear enough to hit
excessive heat levels. There is potential for a return of some
monsoonal moisture as early as Wednesday, but the past few model
runs are showing this to be a very brief episode with more dry air
quickly moving in by the end of the week. At least for now slight
chance PoPs over the high terrain for Thursday and Friday seem
warranted.
&&
.AVIATION...
South-Central Arizona Including KPHX, KIWA, and KSDL:
Southeasterly flow will veer to southwesterly during the afternoon,
but wind speeds will generally remain at or below 10 kt. Meanwhile, latest
convective guidance is pointing towards an increased potential for
showers and thunderstorms across the Phoenix area later this
evening. Any storms that develop will be capable of producing strong
gusty winds and brief heavy rain. Model consensus is that the most
likely wind shift associated with the storms will be from the
northwest. Improving conditions are anticipated after 09z.
Southeast California/Southwest Arizona including KIPL and KBLH:
The active weather will generally remain east of KIPL, but may clip
KBLH this afternoon. Thunderstorms are generally not expected,
however strong storms across western AZ may produce a wind shift out
of the north or east at KBLH this evening. Otherwise, mostly clear
skies are expected with a southerly component to the flow prevailing
through early Saturday.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Monday through Friday: The monsoon high will rebuild across
southeastern Arizona Monday, resulting in above normal temperatures
and generally dry conditions. An increase in moisture is expected
Wednesday as the high shifts eastward. Drier westerly flow across
southeastern California will battle deeper moisture across
southeastern Arizona through the remainder of the week, with showers
and thunderstorms mainly relegated to southern and eastern Arizona.
Near normal temperatures are expected mid to late 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...Percha/Kuhlman
AVIATION...Hirsch
FIRE WEATHER...Hirsch
Area Forecast Discussion
National Weather Service Phoenix AZ
1143 AM MST FRI JUL 1 2016
.UPDATE...Updated Aviation discussion.
&&
.SYNOPSIS...
Another day or two of monsoon moisture will bring chances for
showers and thunderstorms today and again on Saturday over the
eastern Arizona high terrain. A return to drier southwest flow aloft
will begin to take over starting Saturday and end any rain chances
starting Sunday. High temperatures will steadily climb into the
weekend and early next week as the atmosphere becomes drier. The dry
and warm conditions will likely last through much of next week.
&&
.DISCUSSION...
A rather wet morning across parts of South-Central AZ this morning,
as a weak mid-level shortwave helped to trigger showers and isolated
thunderstorms across Pinal and eastern Maricopa counties. Rainfall
amounts have so far been on the light side, mainly in the 0.05-0.25
inch range so far this morning. These showers also pushed
temperatures down this morning across this region, with Phoenix Sky
Harbor seeing a low of 79. The main impact from these morning
showers for the rest of today will to likely retard/delay to
development of new convection this afternoon/evening across this
region. A far as the forecast for the rest of our cwa is concerned,
have decided to increase pops a bit across La Paz and NW Maricopa
counties, since these areas have already cleared out, with the
latest HRRR high-res model showing the development of showers and
thunderstorms as outflows from the remains of strong thunderstorms
that occurred last night over NW AZ move into the region. The other
changes were made to the hourly temp/dewpoint grids to better
reflect current trends.
&&
.PREVIOUS DISCUSSION...
After a rather quiet, cool and cloudy Thursday across southern
Arizona, we should see a rebound in monsoon storm activity this
afternoon and evening. Current analysis shows two separate mid level
circulations across the region, one planted right over southeast
Arizona and the other further to the northwest over southern Nevada.
Moisture levels remain quite high with the 00Z KPHX raob showing a
PWAT of 1.68 inches, but very warm mid levels continue to bring weak
lapse rates and rather meager instability. The mid level circulation
over southeast Arizona is however providing enough forcing to result
in periodic showers stretching as far west as Phoenix. These showers
should continue through around 12Z, but will likely diminish
thereafter as the vorticity center lifts to the northeast.
Westerly drying flow has already overtaken southeast California and
portions of southwest Arizona and will slowly spread across the rest
of southern Arizona throughout today. By this afternoon, the mid and
upper levels will have dried out for the most part except for eastern
Arizona. The drying will likely help us to see more storm development
today versus yesterday as we see quite a bit of clearing skies and
much better heating. The lingering low level moisture will still be
enough to spark off some weak thunderstorms this afternoon, but most
will likely start out over higher terrain spots, especially north of
Phoenix. Steering flow will be generally out of the west at around
10-20 mph, so not especially conducive for outflow propagation into
the lower deserts of south-central Arizona. Hi-res models do indicate
high terrain storms north of Phoenix sending some outflows into the
Phoenix metro which should be enough to spark some isolated storms
over the deserts. Weak winds aloft and the lack of any significant
upper level support should keep storms on the weak side and with
PWATS dropping to below 1.5 inches the flooding threat will be very
minimal. Temperatures today should improve over yesterday`s readings
over south-central and eastern Arizona while similar readings will be
seen over our western zones.
This weekend will bring a continued drying westerly flow, but enough
lingering low level moisture should exist for some isolated eastern
Arizona high terrain afternoon showers and thunderstorms. The
possibility of any activity over the lower deserts is pretty slim
due to the westerly steering flow and PWATS dropping down to around
1.25 inches. By Sunday, enough dry air should be in place for there
to be little chance of any storms even over the high terrain.
Temperatures this weekend will be on the upswing with the drier
conditions and clear to mostly clear skies as highs climb back toward
normal readings.
Next week looks to be mostly quiet as far as any storm potential as
the upper high center generally stays to our southeast providing us
with westerly or southwesterly flow. Temperatures should peak by
Tuesday or Wednesday with some lower desert spots reaching 110F for
highs. 500mb heights do climb to around 592dm and 850mb temperatures
near 30C, but at this point it does not appear enough to hit
excessive heat levels. There is potential for a return of some
monsoonal moisture as early as Wednesday, but the past few model
runs are showing this to be a very brief episode with more dry air
quickly moving in by the end of the week. At least for now slight
chance PoPs over the high terrain for Thursday and Friday seem
warranted.
&&
.AVIATION...
South-Central Arizona Including KPHX, KIWA, and KSDL:
Southeasterly flow will veer to southwesterly during the afternoon,
but wind speeds will generally remain at or below 10 kt. Meanwhile, latest
convective guidance is pointing towards an increased potential for
showers and thunderstorms across the Phoenix area later this
evening. Any storms that develop will be capable of producing strong
gusty winds and brief heavy rain. Model consensus is that the most
likely wind shift associated with the storms will be from the
northwest. Improving conditions are anticipated after 09z.
Southeast California/Southwest Arizona including KIPL and KBLH:
The active weather will generally remain east of KIPL, but may clip
KBLH this afternoon. Thunderstorms are generally not expected,
however strong storms across western AZ may produce a wind shift out
of the north or east at KBLH this evening. Otherwise, mostly clear
skies are expected with a southerly component to the flow prevailing
through early Saturday.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Sunday through Thursday...
Increasing high pressure beginning Sunday is expected to usher in a
slightly drier and warmer weather pattern for most of the week. As
slightly below normal afternoon high temperatures on Sunday increase
to near normal by Tuesday, minimum humidities in the 15 to 25 percent
range will dip to the 10 to 20 percent range on Monday before easing
back up into the 15 to 25 percent range by Wednesday. Expect breezy
southerly to southwesterly winds on Tuesday with gusts to 18 mph to
become breezy to windy on Wednesday with gusts up to 28 mph,
especially in the the lower Colorado river valley. Expect overnight
recoveries to be mostly fair to occasionally good. A slight return in
moisture may begin midweek, allowing for at least slight chances of
thunderstorms mainly over the higher elevations of the Tonto
Foothills and S. Gila county by Thursday.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
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DISCUSSION...Percha/Kuhlman
AVIATION...Hirsch
FIRE WEATHER...Nolte/Sawtelle
AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
945 AM PDT FRI JUL 1 2016
.SYNOPSIS...
Strengthening onshore flow and a deepening marine layer will bring
a cooling trend into the weekend. Marine layer clouds will reach
into the valleys, however warm and dry conditions will prevail in
the mountains and deserts. A gradual warmup is expected early next
week as high pressure builds in over the desert Southwest.
&&
.UPDATE...Nothing really new to add to what is basically a pretty
bland forecast through the weekend at least. A very weak trough
will slowly advance east through California this weekend. Very
minimal impacts locally other than the usual deepening of the
marine lyr and cooler temps. Heights and thicknesses only drop
30-40m through Sunday so overall the air mass isn`t cooling
significantly. But the increase in marine lyr depth and onshore
push will be enough to force temps down back to near normal levels
this weekend. Today we`ll see a few cu over the eastern
mountains as there`s still some lingering moisture and
instability from storms that developed to our east late yesterday
and overnight, but not enough for any storms in our area.
&&
.SHORT TERM...(TDY-SUN)
Overall, 00Z models in good synoptic agreement through the period.
At upper levels, weak trough will linger across California through
the weekend. Near the surface, moderate onshore flow will
continue.
Forecast-wise, the main concerns in the short term will be the
marine layer stratus and temperatures. With the upper trough
lingering and moderate onshore flow, the marine inversion should
deepen a bit from day-to-day. So, will expect stratus/fog to push
into the coastal valleys each night/morning. Each afternoon, the
stratus should dissipate nicely although some beach areas could
be slow to clear. Other than the marine layer stratus, skies
should remain clear as southwest flow aloft keeps any moisture to
the east.
As for temperatures, only minor changes are expected from day-
to-day. There will be some slight cooling today/Saturday then a
bit of warming on Sunday. Overall, temperatures for most areas
will likely be a couple of degrees below seasonal normals through
the weekend.
With the moderate onshore flow, there will be some gusty afternoon
and evening winds across the mountains and deserts. At this time,
winds look to remain below advisory levels although some isolated
areas (such as Lake Palmdale) could experience some gusts near
advisory levels.
.LONG TERM...(MON-THU)
For the extended, 00Z models continue to exhibit decent synoptic
agreement. At upper levels, the area will be between a ridge over
the central states and a trough over the Pacific Northwest. Near
the surface, weak to moderate onshore flow looks to continue.
Forecast-wise, things will remain on the quiet side through the
period. Due to the upper level pattern, southwest flow will
prevail through the week which will keep any monsoonal moisture
well east of the state. So, the only clouds of note will continue
to be the marine layer stratus which should continue to push into
the coastal valleys each night/morning. As for temperatures, there
will be a gradual warming trend as thicknesses rise and the marine
influence decrease slightly each day.
&&
.AVIATION...01/12Z...
At 11Z at KLAX...the marine layer was 2200 feet deep. The top of
the marine inversion was 4700 feet with a temperature of 24
degrees Celsius.
Low clouds have pushed into all coastal and valley areas this
morning, with the exception of the Santa Clarita Valley and the
interior valleys of SLO County. Conditions were mostly IFR from
VTU County northward, and MVFR across L.A. county, except locally
IFR in the valleys. Some IFR conds may push into the Salinas
Valley by daybreak. Expect somewhat slower clearing today, with
VFR conds in the valleys by late morning, and by early afternoon
across the coastal plain. Some cigs could linger near the beaches
through the day. Expect stratus to arrive this evening across the
coastal plain, pushing into the valleys by midnight. Conds tonight
should be mostly MVFR, except IFR in the foothills and on the
Central Coast.
KLAX...Moderate confidence in the 12z TAF. There is a 20 to 30
percent chance that cigs will linger through the afternoon.
There is a 20 percent chance that east winds will exceed 8 knots
between 13z and 17x this morning.
KBUR...Moderate to high confidence in the 12z TAF. There is a 20
percent chance that cigs will clear as early as 16z or arrive as
early as 04z tonight.
&&
.MARINE...01/900 AM...
Small craft advisory for hazardous sea conditions will exist
through late tonight north of Point Conception. The fetch area is
near shore north of the area and the winds are expected to
diminish tonight. otherwise small craft advisory for winds are not
expected through next week Tuesday. Extra currents and surging
along exposed south facing shores will persist through Saturday.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect until 8 PM PDT this evening
For zones 40-41-87. (See LAXCFWLOX).
PZ...Small Craft Advisory for hazardous seas in effect until
midnight PDT tonight For zones 645-670-673. (See LAXMWWLOX).
&&
$$
PUBLIC...MW/RAT
AVIATION...DB
MARINE...30
SYNOPSIS...Sweet
weather.gov/losangeles
Area Forecast Discussion
National Weather Service San Francisco Bay Area
927 AM PDT FRI JUL 1 2016
.SYNOPSIS...A slight cooling trend remains on track into the
weekend, especially inland, with temperatures near seasonal
averages through the 4th of July Holiday Weekend. Late night and
morning low clouds will give way to mostly sunny conditions each
afternoon at least into early next week.
&&
.Discussion...as of 9:30 AM PDT Friday...Typical summer day across
the region with a moderate onshore surface gradient and widespread
clouds at the coast plus adjacent valleys. Satellite animation
shows clouds are slowly burning off around the edges and should
retreat to the coast by late in the morning. Highs will range
from 60s to lower 70s at the coast with mid 70s to upper 80s
inland. Additional cooling is expected over the weekend
particularly for inland spots as 925 MB temps drop 2 to 4C while
the marine layer remains around 2000 feet.
Current forecast appears on track. No major updates planned.
.Previous Discussion...Satellite IR fog product imagery is
showing a similar pattern to yesterday morning at this time with
stratus clinging along the coast from the Golden Gate south
through coastal Monterey County. Stratus is extending inland over
portions of San Mateo County, and extensively in through the
Monterey Bay and Salinas Valley. Light fog is being reported at
Half Moon Bay, Watsonville and at the Monterey airport, with
visibility as low as 1 1/2 miles at times. The fort ord profiler
indicates a marine layer depth of 1500 feet, and surface pressure
gradients are remaining strong northerly as well as onshore with
5.6 mb from ACV to SFO, and 3.3 mb from SFO to SAC.
A baggy upper level trough centered along the west coast will
maintain a cooling trend across the area as well as keep
temperatures cooler than seasonal normals through the holiday
weekend and into next week. Friday is expected to be the warmest
day of the week, especially inland where temperatures will range
from the 80s to upper 90s in the warmest areas. By Saturday,
temperatures are expected to be in the 60s coast...70s around the
bay...and 80s to mid 90s inland. Only a few day-to-day minor temp
fluctuations are expected, but overall the coming week should be
very mild for early July. Night and morning coastal low clouds and
fog and occasional drizzle can be expected through the forecast
period.
&&
.AVIATION...as of 4:30 AM PDT Friday...N-S pressure gradients are
weakening and stratus has developed off the San Mateo coast. SFO
reporting SCT and may occasionally become BKN between 13Z and 16Z.
Clouds are expected to be mainly around SFO with most of the
approach remaining clear. Low clouds are into Monterey bay and
will stay in place through at least 18z.
Vicinity of KSFO...Possible MVFR cigs between 13Z and 16Z.
West to northwest winds to 15 kt after 20Z.
SFO Bridge Approach...vfr overnight except for some morning cigs
from about the San Mateo Bridge north through 16Z.
Monterey Bay Terminals...IFR cigs at kmry/ksns through 18-19z.
&&
.MARINE...as of 09:16 AM PDT Friday...Moderate to strong and
occasionally gusty northwest winds will persist primarily over the
northern waters through the holiday weekend. the strongest gusts
may become gale force. these strong winds will generate hazardous
conditions due to steep fresh swell for portions of the northern
waters. winds will be lighter over the southern waters near shore.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...SF Bay from 1 PM
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 11 AM
&&
$$
PUBLIC FORECAST: Bell
AVIATION: W Pi
MARINE: DRP
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Area Forecast Discussion
National Weather Service San Francisco Bay Area
927 AM PDT FRI JUL 1 2016
.SYNOPSIS...A slight cooling trend remains on track into the
weekend, especially inland, with temperatures near seasonal
averages through the 4th of July Holiday Weekend. Late night and
morning low clouds will give way to mostly sunny conditions each
afternoon at least into early next week.
&&
.Discussion...as of 9:30 AM PDT Friday...Typical summer day across
the region with a moderate onshore surface gradient and widespread
clouds at the coast plus adjacent valleys. Satellite animation
shows clouds are slowly burning off around the edges and should
retreat to the coast by late in the morning. Highs will range
from 60s to lower 70s at the coast with mid 70s to upper 80s
inland. Additional cooling is expected over the weekend
particularly for inland spots as 925 MB temps drop 2 to 4C while
the marine layer remains around 2000 feet.
Current forecast appears on track. No major updates planned.
.Previous Discussion...Satellite IR fog product imagery is
showing a similar pattern to yesterday morning at this time with
stratus clinging along the coast from the Golden Gate south
through coastal Monterey County. Stratus is extending inland over
portions of San Mateo County, and extensively in through the
Monterey Bay and Salinas Valley. Light fog is being reported at
Half Moon Bay, Watsonville and at the Monterey airport, with
visibility as low as 1 1/2 miles at times. The fort ord profiler
indicates a marine layer depth of 1500 feet, and surface pressure
gradients are remaining strong northerly as well as onshore with
5.6 mb from ACV to SFO, and 3.3 mb from SFO to SAC.
A baggy upper level trough centered along the west coast will
maintain a cooling trend across the area as well as keep
temperatures cooler than seasonal normals through the holiday
weekend and into next week. Friday is expected to be the warmest
day of the week, especially inland where temperatures will range
from the 80s to upper 90s in the warmest areas. By Saturday,
temperatures are expected to be in the 60s coast...70s around the
bay...and 80s to mid 90s inland. Only a few day-to-day minor temp
fluctuations are expected, but overall the coming week should be
very mild for early July. Night and morning coastal low clouds and
fog and occasional drizzle can be expected through the forecast
period.
&&
.AVIATION...as of 4:30 AM PDT Friday...N-S pressure gradients are
weakening and stratus has developed off the San Mateo coast. SFO
reporting SCT and may occasionally become BKN between 13Z and 16Z.
Clouds are expected to be mainly around SFO with most of the
approach remaining clear. Low clouds are into Monterey bay and
will stay in place through at least 18z.
Vicinity of KSFO...Possible MVFR cigs between 13Z and 16Z.
West to northwest winds to 15 kt after 20Z.
SFO Bridge Approach...vfr overnight except for some morning cigs
from about the San Mateo Bridge north through 16Z.
Monterey Bay Terminals...IFR cigs at kmry/ksns through 18-19z.
&&
.MARINE...as of 09:16 AM PDT Friday...Moderate to strong and
occasionally gusty northwest winds will persist primarily over the
northern waters through the holiday weekend. the strongest gusts
may become gale force. these strong winds will generate hazardous
conditions due to steep fresh swell for portions of the northern
waters. winds will be lighter over the southern waters near shore.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...SF Bay from 1 PM
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 11 AM
&&
$$
PUBLIC FORECAST: Bell
AVIATION: W Pi
MARINE: DRP
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Area Forecast Discussion
National Weather Service Sacramento CA
911 AM PDT FRI JUL 1 2016
.SYNOPSIS...
Hot and mainly dry this week. A slight cooling trend starting
this weekend and continuing through the week. Isolated late day
thunderstorms possible over the Sierra Friday and Saturday.
&&
.DISCUSSION...
Latest Hi-Res models suggest late day shower and/or thunderstorm
activity remaining east of the Sierra crest. As such, have
updated the forecast to show current model trends. No additional
updates required.
.PREVIOUS DISCUSSION...
Water vapor and RAP model 500 mb analysis showed plenty of dry air
with an area of upper level divergence associated with a weak
upper level trough positioned over NorCal overnight. A lack of a
delta influenced breeze has kept temperatures overnight ranging
between the low to mid 70s for much of the valley...with the
northern end of the Sacramento valley in the lower 80s as of 3 am
PDT.
Plenty of sunshine and warm temperatures will continue today
across the forecast area. Smoke from the Trailhead fire near Todd
Valley could bring some haze and patchy smoke today for
surrounding communities. Temperatures in the valley will range
from the upper 90s in the southern Sacramento Valley and Northern
San Joaquin Valley, but temperatures will reach triple digits
again in the northern Sacramento Valley. Higher elevations will
see 70s and 80s today. The latest high resolution model runs have
some showers and thunderstorms developing in the Sierra Nevada
mountains during the afternoon hours, but the placement should be
to the east of the crest. As a result, there are some slight
chances for thunderstorms at the higher elevations mentioned in
the forecast.
Chances for thunderstorms will continue Saturday afternoon for the
Sierra Nevada mountains south of US Highway 50. High temperatures
will continue to be 5 to 10 degrees above normal for the valley. A
shortwave trough moving across the Pacific northwest will bring
slightly cooler temperatures to the valley for Sunday and Monday
with highs in the lower to mid 90s, and dry weather is
anticipated due to a lack of moisture and instability across the
forecast area.
&&
.EXTENDED DISCUSSION (Tuesday THROUGH Friday)
A weak upper trough will persist over the Pacific Northwest into
extreme NorCal next week, resulting in dry weather and near normal
temperatures. Onshore, southwest winds may be breezy over higher
terrain with our typical Delta Breeze impacting the valley.
Expect high temperatures in the 90s across the Valley, with 70s
and 80s over the mountains. JClapp/JBB
&&
.AVIATION...
VFR conditions the next 24 hours. Winds will generally be around
10 kts or less. Winds in northern Sacramento valley for KRDD and
KRBL will switch from northerly this morning to southeasterly in
the afternoon. Otherwise, onshore flow expected for the rest of
the valley/TAF sites. Delta Breeze will increase again this
afternoon and evening. Areas of smoke near the Trailhead fire.
JBB
&&
.STO Watches/Warnings/Advisories...
None.
&&
$$
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
347 PM CDT FRI JUL 1 2016
.SHORT TERM...(This Evening through Saturday)
Issued at 344 PM CDT FRI JUL 1 2016
This afternoon a deep mid-level trough was stretched across the
eastern U.S. with surface high pressure situated west of the trough
across the Northern and Central Plains. This west-northwesterly flow
aloft combined with low/mid cloud cover supported cooler conditions
this afternoon with highs topping out in the low/mid 80s. Drier
conditions from the surface high were noted across northeast Kansas
where dewpoint temperatures dropped into the 40s with dewpoints in
the 50s to near 60 degrees elsewhere. With these drier conditions
in place, the onset of precipitation will be slower than originally
expected as it will take longer to overcome the drier air and for
the atmospheric profile to become more deeply saturated. As a
result, have lowered PoPs for eastern Kansas late afternoon into
this evening. There actually is still model uncertainty with the
eastward progression of precipitation tonight into Saturday morning
as some models are showing the better lift holding off until
overnight across north central to east central Kansas as the low-
level jet begins to increase over the area. The larger-scale models
still show showers and thunderstorms overspreading the entire
forecast area overnight, while the early afternoon model runs of the
HRRR and RAP suggest that precipitation may not even advance into
northeast Kansas overnight. If this slower solution pans out, then
PoPs are too high across eastern Kansas for overnight tonight.
However, expect moderate to heavy rainfall rates overnight into
Saturday morning with any precipitation that develops as an embedded
shortwave lifts northeastward over the area. Model soundings show a
deep saturation layer developing with PWAT values upwards of around
2 inches. As a result, rainfall amounts of 1 to 1.5 inches will be
possible across portions of north central, central, and east central
Kansas by Saturday morning. While instability will be limited
through tonight, 0-6km bulk shear values may be upwards of 40-50kts
across north central Kansas, so cannot rule out the potential for a
few strong storms tonight with gusty winds and hail being the
primary hazards.
Morning showers and thunderstorms will lift to the northeast as the
first embedded shortwave exits the area and a surface warm front and
inverted surface trough lift into east central Kansas by early
afternoon. Models show the inverted surface trough becoming more
north-south oriented during the afternoon hours, and this boundary
should provide sufficient lift to support additional widespread
showers and storms across north central and far northeast Kansas by
mid to late afternoon. Model soundings show a deep saturation layer
in place with this second round of storms, with PWAT values rising
into the 2 to 2.5 inch range so expect increasing rainfall rates
over north central Kansas during the mid/late afternoon hours. If we
are able to see some breaks in the cloud cover between the morning
and afternoon rounds of precipitation, conditions may destabilize
enough to increase the concerns for strong to severe storms as 40-
50kts of 0-6km shear should still be in place. With a few rounds of
moderate to heavy rainfall possible, a Flash Flood Watch remains in
effect beginning tonight across the entire outlook area.
As for temperatures, with the warm front lifting into east central
Kansas Saturday afternoon, a decent spread in afternoon temperatures
is likely. There is still some uncertainty with where across east
central Kansas this temperature gradient will be, but the current
forecast has high temperatures ranging from near 70 degrees in far
northeast Kansas to the mid/upper 80s across central and east
central Kansas.
.LONG TERM...(Saturday Night through Friday)
Issued at 344 PM CDT FRI JUL 1 2016
The upper trough over the southwest US is forecast to slowly move
east into the Central Plains on Saturday and then into the
Missouri Valley Saturday night. The upper trough should be strong
enough to produce a surface wave along the stalled frontal
boundary across southern Kansas Saturday afternoon. The upper
trough and associated surface wave moves through the area by
Sunday morning. The 12z NAM was faster with the system compared to
the 12z GFS/ECMWF. The slower movement appears to be associated
with a piece of shortwave energy moving into southern plains
Sunday. In all cases, there is a high probability of a heavy
rainfall event over northeast Kansas Saturday night. Low-level
warm advection over surface boundary, synoptic scale UVV which
should have a very moist airmass in place by that point to work with
with PWAT values around 2 inches. The convective resolving models
(ARW and NMM)produce thunderstorms over the forecast area Saturday
night. The 12z NAM/GFS/ECMWF all produce significant pcpn over the
area, although their maximum amounts are north of the area closer to
the apparent 850 mb warm front. This decreases overall confidence
somewhat, but enough confidence remains for high pops and heavy rain
over the forecast area. The lingering shortwave energy on Sunday
supports keep pops in over the east. Will end the flash flood watch
at 12z Sunday morning over the western counties which by then will
have very low chances of heavy precipitation.
Surface high pressure will be over eastern Kansas on Independence
Day which should result in dry weather and below normal
temperatures.
The 12z GFS is more bullish on building the upper ridge into the
Central Plains compared to the 12z ECMWF. The GFS certainly looks
drier and hotter Tue-Fri next week. Will go with a compromise at
this point with very warm temperatures returning with a chance of
thunderstorms due to warm advection Tuesday night. Thunderstorm
chances return late in the forecast as a weak boundary moves into
the area.
&&
.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 1228 PM CDT FRI JUL 1 2016
VFR conditions are expected throughout the period. Introduce TSRA
at all terminals between 05Z and 07Z. Current thinking is cigs
should remain VFR, although MVFR cigs are possible with any
heavier rain band. Showers and thunderstorms should become lighter
in intensity after 14Z tomorrow morning as the main complex of
showers and thunderstorms exit the area.
&&
.TOP Watches/Warnings/Advisories...
Flash Flood Watch from 7 PM CDT this evening through Sunday
evening for KSZ024-026-038>040-054>056-058-059.
Flash Flood Watch from 7 PM CDT this evening through Sunday
morning for KSZ008>012-020>023-034>037.
&&
$$
SHORT TERM...Hennecke
LONG TERM...Johnson
AVIATION...Baerg