Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/28/19
See below for an aviation forecast discussion for the 00Z TAFs.
&&
.SHORT TERM...(This Evening through Sunday Afternoon)
Issued at 313 PM CDT Sat Jul 27 2019
High pressure currently over the area will get pushed eastward this
evening as a low pressure system and associated frontal boundary
approach. Showers and thunderstorms are beginning to develop over
the western part of the state this afternoon. This area of
precipitation will become more widespread this evening, then will
track eastward tonight into the day Sunday. Cannot rule out a strong
storm or two, but instability and shear are forecast to be pretty
minimal. Biggest threat appears to the potential for heavy rain as
PWATs increase into the 1.5 to 2 inch range tonight and remain high
into Sunday. 3 hour flash flood guidance is over 2 inches across
almost the entire CWA, so most areas should be able to handle one to
two inches of rain, but will have to monitor tonight should there be
higher amounts. This area of precipitation looks to exit the CWA
sometime Sunday afternoon, but increasing instability across the
central part of the state could make for a few additional
thunderstorms there Sunday afternoon before quiet conditions return
Sunday night.
Low temperatures tonight will be in the 60s. Highs on Sunday will
rebound back into the 80s, except across the far eastern part of the
CWA where precipitation and cloud cover will linger the longest,
keeping temperatures in the 70s. Lows Sunday night will range from
the mid 50s west to the lower 60s east.
.LONG TERM...(Sunday Evening through Saturday)
Issued at 313 PM CDT Sat Jul 27 2019
The long term starts on Monday with northwest flow aloft and surface
high pressure over the Northern Plains. The surface high shifts
east Monday night through Tuesday night, allowing a weak LLJ and
instability showers and thunderstorms to development. Toward the
end of the work week, ridging aloft, along with southerly flow
will bring heat and humidity into the region. Dew point
temperatures will range in the low 50s and 60s early in the week.
By Friday, dew points should reach the mid to upper 60s. The humid
airmass, along with upper shortwaves will bring the potential for
isolated to scattered showers and thunderstorms Thursday night
through Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 650 PM CDT Sat Jul 27 2019
VFR conditions will prevail this afternoon and evening. Showers
and thunderstorms will spread from west to east across the area
overnight and into Sunday morning. Periods of sub-VFR cigs and
vsbys in heavy rain are possible with the thunderstorms tonight
and Sunday. After 12Z Sunday, MVFR cigs may temporarily develop
over KPIR/KMBG before clearing off/VFR in the afternoon. But look
for MVFR cigs to become the prevailing condition at KABR/KATY
after 12Z Sunday and persist for much of the day.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Dorn
SHORT TERM...Parkin
LONG TERM...SD
AVIATION...Dorn
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1018 PM EDT Sat Jul 27 2019
.SYNOPSIS...
Very warm temperatures will continue this weekend into early next
week. Humidity will increase Sunday, with humid conditions lingering
into midweek. Periodic showers and thunderstorms will be possible,
mainly during the afternoon and evening hours.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
As of 1015 PM EDT, small cluster of showers and embedded
thunderstorms continues to track east across Warren County.
Latest trends overall have been weakening, however still can not
rule out some brief wind gusts to 30-40 mph and heavy rain over
the next 1-2 hours across the Lake George region into
central/northern Washington County.
Elsewhere, some mid level cloud patches continue to drift east
across the Catskills and northern mid Hudson Valley region.
Little in the way of showers elsewhere, although can not
completely rule out an isolated shower as additional shortwave
energy moves eastward overnight.
Previous discussions follow...
As of 715 PM EDT, isolated cluster of thunderstorms will grazing
extreme NE Litchfield County now mainly east of the southern
part of the Barkhamsted Reservoir. There has been a tendency for
the northwest end of this cluster to backbuild, so will continue
to closely monitor trends. Very heavy rainfall and some small
hail is likely with the highest cores, in addition to wind gusts
of 40+ mph.
Elsewhere, watching an area of agitated Cumulus clouds across
the western Mohawk Valley, with some embedded showers,
translating northeast. This seems to be located just ahead of
another weaker shortwave, as depicted at H500 in the latest RAP
13. Will have to monitor trends with this area as well, with
chances for showers and thunderstorms to develop from this area
across the Mohawk Valley, SW Adirondacks, and perhaps extending
as far east as the Lake George/Saratoga region through midnight.
Elsewhere, just patches of mid level clouds. Will keep isolated
shower/thunderstorm mention for all other areas through this
evening in case additional activity develops ahead of
aforementioned mid level impulse.
Previous discussion follows...
As of 310 pm, water vapor imagery shows an upper trough axis
centered roughly over western New England. A few isolated
thunderstorms have developed in association with this trough in an
environment of around 1500 J/kg SBCAPE without much capping. These
have mainly been over the higher terrain and fairly weak, although
one updraft earlier became robust and resulted in some wind damage
near Saugerties. These storms are of the pulse variety without much
wind in the troposphere, so they are generally short lived. Radar
trends over the last hour have been weakening, and would expect this
to continue as the trough shifts east of the area this
afternoon/evening.
Any remaining showers or storms should quickly dissipate tonight
with the loss of diurnal heating. Midlevel flow becomes zonal ahead
of a very weak trough as the weak disturbance from this afternoon
shifts east. A light southerly gradient will exist as the surface
high shifts east as well, so overnight lows are expected to be a bit
milder than last night. Despite the southerly flow, some patchy fog
is possible once again in favored areas that decouple.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
The aforementioned weak trough, which is currently (as of early
Saturday afternoon) generating a few areas of showers and
thunderstorms over parts of Michigan and Ontario, will continue to
shift eastward through the region Sunday. This trough will likely be
accompanied by one or more surface wind shift boundaries/confluence
zones. Although neither of these forcing mechanisms will be very
strong, they may be enough to generate a band of showers and
isolated thunderstorms approaching our far northwestern zones
(southern Adirondacks) by Sunday morning. Downstream, at least
partial sunshine along with dewpoints in the upper 60s will help to
generate SBCAPE in the 1-2 kJ/kg range despite modest midlevel lapse
rates. Current expectation is for continuation of the morning
convective activity and/or redevelopment in concert with the
aforementioned forcing mechanisms. Convection is expected to spread
southeast through the afternoon and evening, becoming scattered in
coverage except for parts of the mid-Hudson Valley and Litchfield
Hills where is will be more isolated. Best coverage appears to be in
the western Mohawk/Schoharie Valleys. Deep-layer shear will be weak
at less than 20 kt which should preclude much of a severe weather
threat. However, there is slightly stronger flow around 30 kt at 700
mb, and forecast soundings suggest fairly steep low-level lapse
rates, so cannot rule out an isolated strong wind gust or two. The
storms should be fairly progressive and PWAT will not be too extreme
at around 1.50-1.75 inches which should make the flash flooding
threat quite low, but as always locally heavy downpours are
possible. Prior to the possible rainfall, heat indices are expected
to reach the lower 90s in the Hudson Valley.
We may continue to see some isolated showers and thunderstorms for
the first part of Sunday night as the weak trough remains in the
vicinity. Otherwise, it should continue to be quite mild and humid
as there will not be a real airmass change.
On Monday, midlevel heights will rise a bit in the wake of the weak
trough, and H850 temps will increase a couple degrees into the upper
teens. This will likely be the hottest and most humid day of the
period (along with Tuesday) with heat indices in the mid-90s in the
valleys. There will be plenty of CAPE around but little in the way
of forcing for ascent. Actually there may be some capping/subsidence
with the height rises, so any thunderstorms are expected to remain
isolated to widely scattered. Very mild and muggy Monday night.
This airmass will remain in place Tuesday ahead of a broad trough
approaching from the west. A band of showers and thunderstorms
associated with the leading edge of the height falls is likely to
work into areas north and west of the Capital District during the
afternoon. There is uncertainty with regard to how far east this
forcing gets as the midlevel ridge may be tough to dislodge, so have
only chance PoPs for much of the area. If the rainfall does not
speed up, we are in for another hot and humid day with heat indices
as high as the mid 90s again.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
On Tuesday night into Wednesday, an approaching upper level
shortwave and associated surface frontal boundary will bring some
showers and thunderstorms to the region, with the greatest coverage
likely just ahead of the front during peak heating on Wednesday
afternoon. It will be fairly warm and muggy, with dewpoints well
into the 60s and high temps reaching into the 80s. With the humid
air mass in place, any thunderstorm will be capable of producing
heavy rainfall.
Behind the boundary, slightly less humid air will move into the
region for Thursday and Friday, with surface high pressure building
into the area from southern Canada. However, the frontal boundary
looks to stall just south of the region, so a few isolated showers
cannot be ruled out for far southern areas for Thursday into Friday.
Sky cover will vary from mostly clear across northern areas to
partly to mostly cloudy across the Catskills, Mid Hudson Valley and
NW CT. Temps look fairly seasonable, with highs in the mid 70s to
mid 80s and lows in the mid 50s to mid 60s.
Fairly quiet weather looks to continue into Saturday, but some
guidance does suggest another weak shortwave may approach at some
point over the weekend. Will keep POPs at slight chc or below with
temps continued close to normal.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
An upper level disturbance will move east of the TAF sites
overnight. A stronger upper level disturbance will then move
across Sunday afternoon.
Mainly VFR conditions through early this evening. Will have to
watch for isolated showers/thunderstorms, which should remain
N/W of KGFL and KALB this evening.
Patchy ground fog will likely develop after 05Z/Sun at KGFL, and
possibly KPSF after 08Z/Sun. Periods of MVFR/IFR will be
possible, with some brief LIFR possible at KGFL, especially
between 07Z-10Z/Sun.
After any patchy fog/low clouds lift between 10Z-12Z/Sun, expect
VFR conditions, until scattered thunderstorms develop in the
afternoon. Have included some Prob 30 groups in the TAFs to
account for this activity, which may form into clusters or small
line segments with embedded IFR conditions.
Winds will be light from the south tonight at less than 5 KT,
and south to southwest at 5-10 KT late Sunday morning into the
afternoon.
Winds will be much stronger, and variable in direction in and
near any thunderstorms.
Outlook...
Sunday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Monday: Low Operational Impact. Slight Chance of SHRA...TSRA.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: Moderate Operational Impact. Chance of SHRA...TSRA.
Tuesday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Wednesday: Moderate Operational Impact. Chance of SHRA...TSRA.
Wednesday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Thursday: Low Operational Impact. Slight Chance of SHRA.
&&
.FIRE WEATHER...
Very warm temperatures will continue this weekend into early next
week. Humidity will increase Sunday, with humid conditions lingering
into midweek. Minimum RH values will be mainly in the 40 to 60
percent range. Periodic showers and thunderstorms will be
possible, mainly during the afternoon and evening hours. Winds
will remain rather light, though slightly stronger from the
southwest at times Sunday.
&&
.HYDROLOGY...
Scattered showers and thunderstorms are expected Sunday,
especially during the afternoon and evening. The storms are
expected to be progressive enough to preclude a flash flooding
threat, though locally heavy rainfall is possible. Any storms
will be mainly isolated to widely scattered on Monday. Scattered
to numerous thunderstorms are expected Tuesday and Wednesday
which could result in locally heavy downpours, but widespread
hydrologic issues are not expected at this time.
Please visit our Advanced Hydrologic Prediction Service /AHPS/
web page for specific area rivers and lakes observations and
forecasts.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Thompson
NEAR TERM...KL/Thompson
SHORT TERM...Thompson
LONG TERM...Frugis
AVIATION...Frugis/KL
FIRE WEATHER...Thompson
HYDROLOGY...Thompson
Area Forecast Discussion
National Weather Service Bismarck ND
942 PM CDT Sat Jul 27 2019
.UPDATE...
Issued at 941 PM CDT Sat Jul 27 2019
Thunderstorms have pushed into southwest North Dakota. Quite a bit
of lightning has shown up with these storms, but so far they have
remained tame. Expect this trend to continue. For late evening
update have increased precipitation chances and cloud cover
through the night.
UPDATE Issued at 650 PM CDT Sat Jul 27 2019
Convection remains to the south and to the west of our area, but
a couple storms are set to push across the Montana border. Current
forecast is handling this well.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 244 PM CDT Sat Jul 27 2019
Forecast highlights for the short term period include chances for
thunderstorms, some possibly strong, and fire weather concerns.
A shortwave trough currently near Yellowstone National Park will
track eastward into South Dakota tonight. As the surface high drifts
off to the east, southerly return flow setting up over the western
Dakotas will help aid in thunderstorm development and maintenance
this afternoon into tonight. Models depict this activity will
largely be centered over South Dakota through tonight, with the
northernmost activity extending to the I-94 corridor. Instability
and shear may be sufficient for a strong to near-severe storm over
far southwestern North Dakota late this afternoon and evening. Hail
will likely be the main threat. Showers and storms will continue to
track eastward across southern North Dakota late tonight into Sunday
morning.
A deepening upper level low currently over British Columbia/Alberta
will quickly move east into Manitoba on Sunday. Associated lee
surface cyclogenesis is ongoing over eastern Alberta, and the
system is forecast to become nearly stacked by Sunday afternoon.
The attendant surface cold front will sweep across the Northern
Plains on Sunday. Model consensus places the front from northwest
Minnesota to Lake Oahe by mid afternoon. It is around this time
that global and mesoscale models agree that convective initiation
will occur along the front. What is uncertain though is how strong
these storms will be. The RAP shows a potential for 2000 J/kg of
CAPE with negligible CIN over far south central North Dakota into
the James River Valley, but deep layer shear looks marginal (no
more than ~30 kts) and low level shear appears generally
unidirectional. Given an expected discrete storm mode, would not
be surprised to see a few sustained updrafts capable of near
quarter size hail. The threat for storms should end by Sunday
evening as the cold front moves off to the east.
Near critical fire weather conditions are forecast to develop behind
the cold front over western North Dakota Sunday afternoon. Steep low
level lapse rates along with seasonally strong cold air advection
and surface pressure rises should promote strong momentum transfer
in the boundary layer, with soundings indicating a mix-down
potential of 30 to 35 kts. The strong boundary layer mixing should
yield surface dewpoints in the mid to upper 30s, at least for a few
hours. This results in relative humidity values around 20 percent
from mid to late afternoon. Because fuels are still relatively
green, will hold off on issuing any fire weather products at this
time.
.LONG TERM...(Sunday night through Saturday)
Issued at 244 PM CDT Sat Jul 27 2019
The synoptic pattern for next week calls for upper level high
pressure over the Southern High Plains, placing North Dakota at the
northern edge of broad upper ridging. This setup will give us a
warming trend and periodic chances for showers and thunderstorms as
various disturbances pass over the top of the upper ridge through
much of next week. Both the GFS and ECMWF show a stronger shortwave
moving through toward the end of the work week. Instability and
shear may be sufficient for strong to severe storms at times, but it
is far too early to nail down any specifics.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 650 PM CDT Sat Jul 27 2019
Scattered thunderstorms possible primarily over southern areas
tonight, and mainly over eastern areas on Sunday. Otherwise, VFR
conditions expected.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJS
SHORT TERM...Hollan
LONG TERM...Hollan
AVIATION...JJS
Area Forecast Discussion
National Weather Service Denver/Boulder CO
841 PM MDT Sat Jul 27 2019
.UPDATE...
Issued at 838 PM MDT Sat Jul 27 2019
Have cleared out the chance of storms out of the foothills, urban
corridor and adjacent plains as storms continue over the far
eastern plains and the northern mountains. Should see the rest of
the activity die down over the next 2 to 3 hours. The HRRR and
NAM-Nest still show some hints of storms, currently over far
northwestern Colorado, continuing over the mountains after
midnight and through sunrise as the upper trough translates across
the area. This seems plausible so have kept the slight chance in
the forecast. Other than that, no changes are needed to the
forecast.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 222 PM MDT Sat Jul 27 2019
Storms associated with a shortwave trough will be ongoing this
evening mainly across the plains with a few isolated storms
elsewhere. The SPC mesoanalysis page is indicating precipitable
water values near 1.3 inches over the far eastern plains, so heavy
rain and minor flooding will be possible with the strongest
storms. The axis of the mid level shortwave will move through
northern Colorado late tonight and into early tomorrow morning.
This may provide enough forcing for a few showers especially over
the northern mountains but any showers that do form will be very
light due to the lack of instability. POPs were increased during
this time period to indicate a slight chance of rain.
AVA on the backside of the departing shortwave will provide
subsidence over our CWA on Sunday. Winds at the surface will turn
northerly over the plains with gusts up to 30 mph. Precipitable
water values will be much lower as the downslope flow dries
conditions out. A few stray showers and storms may form during the
afternoon but very little rainfall is expected due to the
aforementioned dryness. Otherwise, highs will be about the same
as Saturday with more sunshine.
.LONG TERM...(Sunday night through Saturday)
Issued at 222 PM MDT Sat Jul 27 2019
A slight chance for thunderstorms will continue into Sunday
evening. A warm layer above 500mb will make any substantial
vertical difficult. In addition to this, the dry airmass will keep
chances for thunderstorms very low through Sunday evening.
The weather over the upcoming week will be mainly influence by
the position of the upper level high over the southwest U.S. On
Monday, the high will be centered near the Four Corners. Clockwise
flow around the ridge will keep the monsoon moisture to the west
of Colorado. An easterly low level flow will bring moisture to
areas east of the mountains. Warm mid levels and a lack of forcing
will keep storms isolated at best.
The ridge slowly wobbles to the east Tuesday through Thursday,
this will allow monsoon moisture to slowly increase over the
Central Rockies. At this time, best chance for thunderstorms
appear to be on Thursday when a short wave trough embedded in the
southwest flow aloft tracks across the region. Limited shear and
instability will keep the severe threat low. Heavy rain will be
the biggest issue, mainly on Thursday. Temperatures through mid
week look to be near normal with readings in the upper 80s to
lower 90s.
Chances for start to decrease on Friday as the ridges starts to
retrograde back to the west. This starts to cut off the monsoon
moisture. There still should be enough moisture and instability
for isolated to scattered storm coverage Friday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 838 PM MDT Sat Jul 27 2019
Storms have since pushed far east, with no more expected tonight.
Winds were southerly from outflow of previous storms, and will
trend toward drainage tonight before a cold front pushes through
the area tomorrow morning. Winds will turn northerly during the
mid to late morning with gusts up to 25 knots. The stray storms
that may form over the mountains tomorrow should not reach the
airports. VFR ceilings and visibility are expected through Sunday
evening.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Kriederman
SHORT TERM...Danielson
LONG TERM...Meier
AVIATION...Kriederman
Area Forecast Discussion...UPDATED
National Weather Service Cheyenne WY
839 PM MDT Sat Jul 27 2019
.UPDATE...
Issued at 839 PM MDT Sat Jul 27 2019
Quick update as we head into late evening. Dropped PoPs across
the CWA with loss of instability. CAMS not showing much if any
redevelopment behind the main line of storms exiting to the east.
We also canceled the Flash Flood Watch for Niobrara, Northern
Souix, and Dawes counties given we don`t see much any re-
development into the area and storms that moved through earlier
were progressive in movement. Otherwise, much less in the way of
showers and thunderstorms expected for tomorrow, with greatest
coverage (chance PoPs) expected across the Nebraska Panhandle.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 138 PM MDT Sat Jul 27 2019
Summary: Scattered to numerous showers and thunderstorms ongoing
and expected to continue through the afternoon and evening hours.
Main thunderstorm hazards will be localized heavy rainfall,
frequent lightning, and wind gusts of 30 to 40 mph in the
strongest of outflows. Storm strength will decrease through the
late evening as they shift from Wyoming into Nebraska Panhandle
and then farther east. A Flash Flood Watch remains in place as
storms will be slow moving and could produce locally high rainfall
amounts causing local road and poor drainage impacts this
afternoon through early Thursday morning.
Weather Details: A shortwave trough analyzed via water vapor
satellite and RAP output is shifting across central WY this
afternoon and aiding enhanced synoptic lift. Combination of this
lift and modest instability near 1250 J/Kg MLCAPE and eroding
MLCIN is supporting scattered to numerous showers along with
isolated to scattered thunderstorms over the high terrain and High
Plains of Wyoming so far this afternoon. Deep layer shear remains
20-25 knots and thus overall storm mode will be pulse-like with
clusters that propagate along multi-directional outflow
boundaries. Anomalously high PWATs near 1" to 1.25" across east
Wyoming and even higher into the Nebraska Panhandle are
supporting the large coverage of showers and storms. This will
also heighten the risk for localized heavy rain in the slow storm
motion environment that could result in local flooding impacts.
SPC HREF continues to highlight Niobrara and northern Nebraska
Panhandle into SD for pockets of concentrated rainfall where the
combination of synoptic lift combines with instability, storm-
clustering, slow storm motion, and greater PWATs. Main time frame
for flash flooding potential will be this afternoon for Niobrara
and spread east into Nebraska through late afternoon through late
evening and early overnight hours as shortwave exits 08-12Z
Sunday Morning. Some upscale growth in the clustering could occur
into a semi-organized MCS in Nebraska and this could exacerbate
flooding impacts. Future shifts may need to evaluate convective
trends if this upscale growth occurs and if the Flash Flood Watch
may need to be cancelled early before 12Z Sunday.
.LONG TERM...(Sunday through Friday)
Issued at 303 AM MDT Sat Jul 27 2019
Storms will dissipate late tonight and early Sunday as the ridge
builds back in temporarily. A few showers and thunderstorms will
be possible again Sunday afternoon and evening, though coverage
should remain isolated to widely scattered. Heavy rain will again
be possible with any stronger storms.
The overall pattern will remain essentially the same through the
extended as the ridge remains in place and shortwave disturbances
rotate through. Warm temperatures and afternoon convection will be
the status quo through mid week. By mid week, ridging will
increase with 2 to 3 DAM 12 hour height rises expected Wednesday
and Thursday. This should limit convection somewhat and keep
things quite warm. High pressure will continue to dominate the
the western 3rd of the CONUS through the remainder of the forecast
cycle. Models are in good agreement of keeping temperatures warm
with periods of isolated convection in the afternoons. More robust
convection will be likely with any stronger shortwaves that
develop in the flow aloft, although these will be difficult to
resolve beyond 2 and 3 days out. Expect continued warm weather
with showers and thunderstorms possible in the afternoons and
evenings.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 633 PM MDT Sat Jul 27 2019
Scattered thunderstorms moving across eastern Wyoming and the
Nebraska Panhandle early this evening with periods of
thunderstorms with gusts to near 40 mph expected at times
Scottsbluff, Alliance, Chadron and Sidney. Will keep vicinity
showers at Cheyenne given weakening showers may work into the
Cheyenne area. Will leave a period of thunderstorms through 02Z
for Laramie with small area of storms moving through that area,
and vicinity showers out near Rawlins through the early evening.
CAMS showing activity weakening as we go past sunset. We did bring
in some MVFR ceilings across the Nebraska Panhandle late tonight
into early morning.
&&
.FIRE WEATHER...
Issued at 138 PM MDT Sat Jul 27 2019
Fire weather concerns will remain low today despite the number of
thunderstorms and lightning as most of the storms should have
adequate rain with them and not pose a dry lightning risk. Overall
minimum humidity values will remain elevated today with scattered
to numerous showers and storms across the region.
Drier and warmer temperatures look to the in store for Sunday
and into early next week. Zone 304 is now labeled to have
critical fuels and Humidity will drop near 15 percent Sunday
and Monday. Winds look to remain below 25 MPH at this time but
elevated to near-critical conditions appear possible in Zone 304
over the coming days. If winds, look to be higher, a short-term
Red Flag may be needed.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
UPDATE...JG
SHORT TERM...JSA
LONG TERM...AL
AVIATION...JG
FIRE WEATHER...JSA
Area Forecast Discussion
National Weather Service Green Bay WI
1023 PM CDT Sat Jul 27 2019
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Sunday
Issued at 232 PM CDT Sat Jul 27 2019
The latest RAP analysis and satellite/radar imagery show a cold
front slowly dropping south from southwest WI to about Appleton
and Kewaunee early this afternoon. Mixed layer instability ahead
of the front is gradually increasing upwards of 1200 j/kg over
east-central WI, though the clouds along the front are behaving
due to poor convergence and lack of large scale ascent. It remains
uncertain whether storms will develop over east- central WI this
afternoon or develop further south. With further destabilization,
the highest chances for storms will occur from about Oshkosh to
Kewaunee in the 3 pm to 7 pm time period. Some guidance,
particularly the hrrr, keeps precip south of Manitowoc, so chances
will remain below 30 percent for east-central WI in general.
Brief gusty winds and small hail will be the main threats in the
strongest storms. Looking elsewhere, weak high pressure is
shifting east to the north of the front over the northern
Mississippi Valley, with widespread fair weather clouds popping
from northern Minnesota into northern WI.
Tonight...The front remains forecast to continue to move south
into southern WI or northern IL by early Sunday morning. The weak
surface high should move into the area after midnight, which will
promote clearing skies within a cooler and drier airmass. This
should set the stage for patchy fog to develop north and west of
the Fox Valley in the early morning hours. Cooler low temps
ranging from the mid 50s north to mid 60s over the southern Fox
Valley.
Sunday...As shortwave energy moves east over the Dakotas and
Minnesota, increasing southwest winds will cause the front to
return northward during the day. This front will push across much
of north-central and into east-central WI in the afternoon,
causing thunderstorm chances to increase. With daytime heating,
mixed layer instability is projected to increase to 1500 j/kg over
central WI, so not out of the question that a few strong storms
could develop at peak heating. Effective shears of 20 kts,
however, will limit storm organization, and most likely keep
storms rather pulsey in nature. Temps will be similar to todays
readings and range from the low to mid 80s.
.LONG TERM...Sunday Night Through Saturday
Issued at 232 PM CDT Sat Jul 27 2019
The main issue in the long-term portion of the forecast will be the
potential for showers and thunderstorms Sunday night into Monday
before quiet weather moves in for much of the work week.
Sunday night into Monday: A surface low is expected to lift from
northwest WI to eastern Lake Superior by 12Z Monday. At the same
time, the low is expected to deepen as shortwave energy and a deeper
upper-level trough approaches from the Plains. As the low deepens, a
warm front is expected to lift northward through the area through
the evening hours, followed by a cold front overnight into Monday
morning. South of the warm front and ahead of the approaching cold
front, instability will increase into the early evening hours across
the area. Models are generally showing between 500 and 1000 J/kg of
MUCAPE with deep layer shear values around 20 to 25 knots along and
ahead of the cold front. The better shear/instability would be early
in the evening before instability decreases into the late evening
and overnight hours. A few strong to severe thunderstorms are
possible, but the limited amount of shear and decreasing instability
would likely limit this to the early evening hours. Otherwise, the
added forcing along the cold front and increased moisture will allow
shower and thunderstorms to push through the area from west to east
throughout the night into Monday morning. Some heavy rainfall is
possible under any thunderstorms as PWAT values are progged to be
between 1.5 to 2.0 inches along and ahead of the front. It does look
like the line of storms would be transient enough to keep flooding
from be a greater concern. By Monday afternoon, drier air will
filter in from the west as a surface ridge builds into the area.
Aloft, the upper-level trough axis will slide directly overhead.
This will mainly lead to some gusty afternoon winds up to 25mph as
deeper mixing occurs. Otherwise, much quieter weather will move in
for the afternoon hours. Highs will be in the upper 70s to low 80s,
coolest central/north-central. Overnight lows will be in the 60s for
most locations.
Monday night through Thursday: The aforementioned surface ridge will
continue to build across the western Great Lakes through this time
period, keeping fairly tranquil weather in place. Some afternoon
fair weather CU may develop each day, especially Tuesday and
Wednesday as the area will be on the western side of the slowly
departing upper-level trough. Otherwise, look for partly cloudy
skies, generally light winds and more comfortable temperatures
through this time period. High temperatures will be in the mid to
upper 70s to near 80. Overnight lows will drop into the 40s and 50s.
Rest of the extended: The high pressure system is expected to shift
slowly off to the east through this time period, allowing the next
system to approach from the west. As is typical this far out, model
solutions differ on how quickly the surface ridge slides eastward.
At this point, will stick with a blend of the models, bringing an
increase in temps, some cloud cover and low precip chances by next
weekend.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1020 PM CDT Sat Jul 27 2019
A weak frontal boundary continues to sag south and away from the
area late this evening. Convection firing along the boundary will
drift off to the south as well. Quiet weather is still expected
for the rest of the night as a low-level ridge shifts through the
region. There is some potential for fog, but it`s been a while
since most areas received significant rainfall so still plan to only
carried it at the most climatologically favored locations.
Quiet weather with good flight conditions will persist through the
morning and into the early afternoon hours Sunday. Convection is
likely to begin spreading across the area as the frontal boundary
advances back to the north during the afternoon.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......Cooley
AVIATION.......Skowronski
Area Forecast Discussion
National Weather Service Houston/Galveston TX
1006 PM CDT Sat Jul 27 2019
.DISCUSSION...
Showers and thunderstorms that affected portions south of I-10
and east of I-45, dissipated during the evening hours with the
loss of diurnal heating. Mostly clear skies along with light and
variable winds are expected tonight. Low temperatures are expected
to range between the mid and upper 70s.
Sunday, onshore flow is expected to continue along with low level
moisture transport from the Gulf increasing rain chances. During
the morning hours, passing showers could develop across the local
waters and move northward into the coastal regions of southeast
TX. During the afternoon hours, development of showers and
isolated thunderstorms can be expected inland, particularly along
shower and sea breeze boundaries as diurnal heating peaks. High
temperatures will again range between the low to mid 90s.
24
.AVIATION...
00Z Aviation...Still a few well inland isolated showers
remaining, and these should dissipate during the next hour
or two. Expect slightly more shra/tsra overage tomorrow
aft as compared to today. S winds will continue. 33
PREV DISCUSSION... /ISSUED 317 PM CDT Sat Jul 27 2019/
SHORT TERM[Tonight through Sunday]...
Isolated showers and storms have formed near KHOU this afternoon
along the sea breeze and other outflow boundaries from earlier
convection. Isolated storms should continue to pop up the next
couple of hours given enough moisture, daytime heating and
convergence along boundaries. Storms should dissipate towards the
evening hours as heating is lost. Main impacts from the storms will
be brief heavy rain, lightning and gusty winds.
Tomorrow should be similar to today with storms developing with
heating during the day. Models do show increased moisture with
higher precipitable water. Hi-res models show a bit more scattered
activity than today so decided to go with 40 PoPs mainly with a few
spots near 50 percent. Temperatures should be relatively persistent
with highs in the mid 90s like today and yesterday.
Overpeck
MARINE...
A light to moderate S-SE flow will prevail this weekend into early
next week with high pressure over the central Gulf of Mexico and a
weak trough of low pressure in the lee of the Rockies. Scattered
showers and thunderstorms will be possible the next few days as
higher moisture from the central Gulf moves into the region. Better
chances of storms are expected mid week.
Overpeck
AVIATION [18Z TAF Issuance]...
Latest radar trends and vis satellite show some TCU developing
mainly just E and SE of KIAH. Temps are hitting upper 80s so
another hour or two from reaching convective temps based on
soundings in the area. HRRR trends have shown convection
developing near KHOU/KIAH/KCXO so decided to do a VCTS for a
couple hours this afternoon. Kept rest of the TAFs dry based on
this guidance. Also looks like VFR conditions are expected
although we will need to monitor KCLL to KUTS for MVFR conditions
in the morning. May also see some patchy fog at KCXO and KLBX but
low enough confidence not to include in TAF for now.
Overpeck
LONG TERM [Sunday night through Saturday]...
Large upper ridge over southern and central Rockies will remain
the dominant weather feature for us as it holds through the week.
This will keep somewhat unsettled weather in play, especially for
mid-week when a shortwave trough will ride down the front side of
the ridge and could increase rain chances Tue and Wed. Otherwise,
expect a fairly uniform weather week near climatology with temps
away from the water rising well into the lower to mid 90s each
day pushing max HIs into the triple digits.
Evans
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 76 95 76 97 75 / 10 30 10 20 20
Houston (IAH) 77 93 77 95 77 / 10 50 10 30 10
Galveston (GLS) 82 88 82 89 80 / 20 30 10 20 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
Discussion...24
Aviation...33
Area Forecast Discussion
National Weather Service North Platte NE
640 PM CDT Sat Jul 27 2019
.SYNOPSIS...
Issued at 318 PM CDT Sat Jul 27 2019
H5 analysis from earlier this morning had high pressure
located over southern Arizona. Ridging had flattened over the
western CONUS over the past 24 hours as a trough of low pressure
approaches the Pacific northwest. East of the main trough, a
secondary trough of low pressure extended from eastern Idaho into
northern Utah. East of this feature, a weak upper level disturbance
was lifting across sern Wyoming and nern Colorado, and had led to a
shroud of mid and high level cloudiness across western and north
central Nebraska. Light rain showers and even an isolated
thunderstorm or two had developed and was present across western and
north central Nebraska midday. With partly to mostly cloudy skies
present across the forecast area, 2 PM CDT temperatures ranged from
81 at Ainsworth to 90 at Imperial.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 318 PM CDT Sat Jul 27 2019
The main forecast concern in the near term is precipitation
chances and severe potential tonight. Right out of the gate, there
are some significant timing differences between the HRRR and
NAM12/NAM NEST solns this morning. The HRRR is 3 to 6 hours faster
with the onset of convection over the panhandle. The HRRR
develops storms in the western panhandle around 21z with the NAM
NEST around 23z and the NAM12 around 2-3z. ATTM, believe the NAM12
is way too slow with the onset of precipitation in the forecast
area and have opted for the faster HRRR/NAM NEST solns. That being
said, went ahead and slowed down the onset of precipitation in
the grids this evening as the inherited forecast had pops
mentioned across all of north central Nebraska by early evening.
As for the threat of severe storms, it appears fairly limited
given the forecast 20 to 30 KTS of deep layer shear. Low level
winds remain very weak PER the 12z LBF sounding, so most of the
shear is of the mid level variety. This would favor potential for
strong wind gusts and marginally severe hail with the hail threat
being early on. The wind threat should carry over into the
overnight as convection takes on a more linear mode. As for
precipitation chances, they will be highest over the northern
forecast area as the short range solutions focus the nose of the
low level jet across the central and northern sandhills overnight.
Overnight, a cold front will pass through the western half of the
forecast area with this feature clearing the remainder of the
forecast area Sunday afternoon. The threat for thunderstorms will
linger in the east at least through midday Sunday before exiting
to the east along with the front. Drier and cooler temps are
expected behind the front with highs Sunday in the middle 80s.
.LONG TERM...(Monday through Saturday)
Issued at 318 PM CDT Sat Jul 27 2019
High pressure aloft will build east into the southern Rockies,
then southern high plains early in the work week. The next shot of
precipitation is expected Monday night into Tuesday as a warm
front lifts east across the forecast area. Behind the warm front,
warmer temperatures will set in with readings returning to the 90s
in the west. However, some decent model differences are noted
between the GFS and ECMWF solns this afternoon. Most notably, the
degree of cooler air which tries to back into the eastern forecast
area next week. The GFS is much stronger with this cooler air and
the latest MEX guidance latches on to this. The ECMWF is warmer
and is the preferred solution attm. In fact, the EC soln builds
the high into the TX panhandle by Thursday with a significant
amount of heat building into the high plains Thursday into Friday.
The GFS soln has the high farther southwest, with a cooler soln
for western Nebraska. In light of the model differences, a blended
forecast yields widespread 80s with temps approaching 90 in the
west next week. Will stick with this soln for now, but wouldn`t be
surprised if forecast temps trend warmer as we approach the
middle of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 640 PM CDT Sat Jul 27 2019
The primary aviation weather concerns for western Nebraska are
thunderstorms, wind shear, and low ceilings. Scattered
thunderstorms will overspread the Sandhills tonight, affecting the
northern terminals the most (KGRN, KVTN, KANW, KONL). Gusty
erratic winds, rapid drops in cigs/visby from heavy rain, and hail
are possible. TSRA overage will be more isolated farther south
(KOGA, KLBF), but the low level jet will result in wind shear
conditions. As the storms are moving east overnight, surface winds
will switch to southwest and eventually northwesterly. MVFR cigs
are possible for northern Neb toward dawn Sunday. Low clouds give
way to mid/high clouds Sunday morning, but northwest surface
winds will be rather gusty in the afternoon.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...Snively
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
929 PM EDT Sat Jul 27 2019
.SYNOPSIS...
High pressure will reside over the Mid-Atlantic through the
weekend, then move offshore early in the coming week. A cold
front will approach from the Ohio Valley towards the middle of
the week.
&&
.NEAR TERM /THROUGH SUNDAY/...
At 01Z, several isolated showers west of the Blue Ridge are
progressing eastward. 00Z HRRR has this activity diminishing in
areal extent and lasting until about midnight, with the majority
of the activity not making it east of the Blue Ridge. Patchy fog
will develop overnight west of the Blue Ridge, especially in
those areas that had showers this evening. Min temps overnight
near normal, with lows near 70F in the I-95 corridor, and mid
60s generally west of I-95 corridor. The exception will be in
sheltered valleys in the I-81 corridor, where lows around 60
are likely, along with patchy fog.
Sunday will start sunny except in those locales that have patchy
fog, which will burn off rapidly by 9 AM. Expecting cumulus to
form around noon, similar to today. High temps Sunday will be a
couple of degrees warmer than today, and the dewpoints will rise
about 5 degrees warmer than today. So overall, it will not feel
as comfortable on Sunday as today with higher dewpoints causing
higher heat indices in the lower-to-mid 90s.
Additionally, the HREF is showing isolated shower activity
generally north of I-66/US50 mid-afternoon through sunset, so I
have added this feature to the forecast. No severe weather or
marine hazards expected for Sunday attm.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
After whatever activity pushes east or weakens Sunday evening,
the balance of Sunday night will turn out dry. With the
southerly flow continuing, it will again be a little warmer and
more humid, with lows staying in the upper 60s to 70s. Patchy
fog/mist will again be possible in more rural locales inland.
Monday, the trough and front to the west will begin to move
closer, though locally, a ridge will actually build aloft.
Combined with the continued southerly flow, and Monday should
continue the slow creep upward in heat and humidity, with
widespread low 90s and a few mid 90s. Heat indices may reach
within 5 degrees of advisory levels, but think they stay below.
With the ridge nearby still, convection may remain suppressed
much of the day, though something isolated will be possible
especially in the mountains, or along the Mason-Dixon line.
Whatever does develop should dissipate in the evening, however,
and Monday night will turn out just like Saturday and Sunday
night, just a little warmer and more humid than Sunday night.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
On Tuesday a mid to upper level trough will be embedded over
the eastern CONUS as a surface front extends along the eastern
Great Lakes and into the Ohio Valley. This will enhance the
development of showers and thunderstorms especially west of the
Blue Ridge. The front will slowly move into our region Wednesday
into Thursday which will increase cloudiness and will maintain
the chance for showers and thunderstorms each day, especially
in the afternoon/evening hours as it is enhanced by diurnal
heating. The mid/upper level trough axis moves away on Thursday
and surface front lingers near our region Friday into Saturday.
This will continue the trend of afternoon/evening showers and
thunderstorms, but will depend on location of the frontal
boundary. If it moves further south, the end of the week could
be drier. &&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
Pop-up shower impacting KMRB with MVFR conditions for vsby attm.
This shower will also add to the potential of MVFR for mist at
KMRB between 08Z-11Z.
Otherwise, VFR through Monday night all terminals overall.
Isolated TSRA possible Sunday afternoon for KMRB, KBWI, and
KMTN. Modest visibility reductions are possible at CHO and MRB
during the early morning hours each of the next three mornings,
but confidence not high enough to put restrictions in the TAFs
for tonight just yet. An isolated shower or thunderstorm also
cannot be ruled out, but odds are less than 15 percent, so also
not included in the TAFs.
Generally VFR conditions are expected between Tuesday and
Friday, with periods of sub-VFR condition during
afternoon/evening shower/thunderstorm activity.
&&
.MARINE...
High pressure will provide light winds through most of Sunday.
Late in the day and at night, southerly channeling is expected
to develop as the high moves offshore, which may bring marginal
SCA conditions to portions of the open bay. This probably wanes
during the day Monday but may return Monday night. Did not yet
have confidence to issue an SCA yet. Otherwise, most of the time
should be storm-free, but an isolated shower or thunderstorm
cannot be completely ruled out Sunday afternoon/evening and
again Monday afternoon/evening. Odds generally less than 15
percent.
Showers and thunderstorms are possible in the afternoon/evening
hours over the waters between Tuesday and Friday. Periods of
SCA conditions are possible each day as well.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.
&&
$$
SYNOPSIS...RCM
NEAR TERM...Lee
SHORT TERM...RCM
LONG TERM...IMR
AVIATION...Lee/IMR/RCM
MARINE...IMR/RCM
Area Forecast Discussion
National Weather Service Melbourne FL
824 PM EDT Sat Jul 27 2019
.UPDATE...
East coast breeze and outflows have made it made it west of metro
Orlando with a slight chance shower/thunderstorm chance for the far
western interior including Lake county for a few more hours.
Stronger storms near Lake Okeechobee may allow for some convective
development to push back toward the east coast, supported by the
HRRR model, but think coverage will remain in isolated range for
southern portions of the forecast area and have also capped POPS
around 20 percent there. Expect another late evening update to
remove POPs entirely for the overnight as convection diminishes with
loss of daytime heating. Lows in the lower to mid 70s.
&&
.AVIATION...
Isolated convection should remain mainly west of all terminals into
late evening before dissipating. Generally VFR conds overnight with
CHC SHRA/TSRA for cstl terminals into early to mid afternoon and
then progressing toward the interior. Have included VCTS most
terminals for Sunday afternoon.
&&
.MARINE...
Light onshore flow expected this evening then expected a trough to
develop across the waters by late tonight. Seas generally up to 2 ft
with some 3 ft seas possible across the nrn offshore waters in a NE
swell.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 73 88 73 88 / 10 50 30 50
MCO 74 93 74 93 / 10 50 20 60
MLB 74 90 74 89 / 10 40 30 60
VRB 72 90 72 90 / 10 40 30 50
LEE 75 93 74 92 / 20 50 20 60
SFB 74 92 74 92 / 10 50 20 60
ORL 75 93 75 92 / 10 50 20 60
FPR 72 90 72 90 / 20 40 30 50
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Volkmer/Sedlock
Area Forecast Discussion
National Weather Service San Francisco Bay Area
842 PM PDT Sat Jul 27 2019
.SYNOPSIS...Strong high pressure will maintain hot conditions for
the interior valleys and hills through Sunday. Seasonably mild
weather will persist along the coast with a shallow marine layer
and light onshore flow in place. Cooling will begin to develop
inland by late Sunday afternoon as the next upper level trough
approaches the coast and onshore flow starts to ramp up. By Monday
temperatures will cool significantly across inland areas as a
well established marine layer and stronger onshore breezes return.
Temperatures are then expected to remain near or slightly below
seasonal averages for the rest of next week.
&&
.DISCUSSION...As of 8:40 PM PDT Saturday...Building high pressure
aloft pushed inland temperatures sharply higher today,
particularly in the hills and interior valleys. Meanwhile, a
persistent shallow marine layer close to the ocean, combined with
light onshore flow, kept coastal areas seasonably mild. There was
a hefty 50 degree spread today between the coolest and hottest
high temperature in our forecast area: from a foggy 59 at Ocean
Beach in San Francisco to a sizzling 109 at the southern Salinas
Valley town of Bradley in southern Monterey County. Despite the
hot temperatures inland, no record highs were set or tied today.
Current Fort Ord profiler data shows that the marine layer depth
has decreased to slightly less than 1000 feet. The Half Moon Bay
Airport is currently reporting a visibility of 1/2 mile and it`s
likely there will be patchy dense fog near the immediate coast
overnight and into Sunday morning. A forecast update was completed
earlier in the evening to add patchy fog to most coastal zones
tonight and early Sunday.
The upper ridge will maintain very warm to hot conditions across
our inland areas into Sunday. High`s tomorrow are expected to be
similar to today for the interior valleys and hills, and overnight
lows tonight will likely be slightly warmer than last night. Some
locations in the hills may not cool below 80 overnight. Heat Risk
is expected to remain moderate to high in the warmest inland
valleys and hills through tomorrow. Therefore, the Heat Advisory
for the East Bay Interior Valleys and Hills, and all inland
portions of Monterey and San Benito Counties, will continue
through Sunday. The upper ridge is forecast to begin to break down
late on Sunday as an upper trough begins to develop offshore.
This will trigger an inland push of marine air starting late Sunday
afternoon and continuing through Sunday evening. Thus, the
coastal valleys will likely see some cooling already tomorrow. All
areas will experience significant cooling by Monday as gusty
onshore winds and a deepening marine layer provide relief. The
inland valleys are forecast to cool by as much as 20 degrees by
Monday.
The models agree that a weak upper trough will persist just off
the West Coast through much of next week. Thus, temperatures for
the entire work week are expected to be near normal, or slightly
cooler than normal.
Looking at the longer range, the ensemble mean from both the GFS
and ECMWF shows an upper ridge rapidly strengthening near the Four
Corners late next week and then expanding westward across
California next weekend. Thus, we may see another warm weekend for
interior portions of our area, although probably not as warm as
this weekend.
&&
.AVIATION...as of 4:45 PM PDT Saturday...Upper level high over
the area has compressed the marine layer. Strong northerly
gradients are developing as well with the ACV-SFO gradient at 6.4
mb. This will keep stratus out of the SFO Bay Area tonight. Low
confidence of fog at STS. Stratus along the coast should spread
into the MRY Bay Area but later than usual.
Will have to watch the smoke from wildfire in southern Oregon.
Northerly flow may blow some smoke over the Bay Area tonight with
slight impacts to slant-range vsbys. This is supported by the
HRRR Near-Surface Smoke Model.
Vicinity of KSFO...VFR. Northwest winds 15-18 kt decreasing after
04Z.
SFO Bridge Approach...VFR.
Monterey Bay Terminals...Stratus along the immediate coast but it
should stay out of MRY and SNS until after midnight.
&&
.FIRE WEATHER...As of 8:30 PM PDT Saturday...Humidity recovery
will be poor once again on Saturday night for elevations above
1000 feet. Very warm and dry conditions will persist across inland
areas through Sunday. However, winds will remain light through
early Sunday afternoon. Main period of concern is late Sunday
afternoon and evening when the initial inland push of marine air
gets underway. Gusty westerly winds late Sunday afternoon and
evening will initially be dry which could create a short duration
of critical conditions. Onshore winds will bring significant
cooling and much higher relative humidity values by late Sunday
night and Monday. The higher hills will still remain quite dry
Sunday night but even those areas are expected to to see
significant improvement by Monday night as the marine layer
deepens.
&&
.MARINE...as of 04:29 PM PDT Saturday...Breezy to locally gusty
northwest winds across the outer waters as well as the inner
waters north of Point Reyes for the rest of Saturday. Northwest
winds strengthen across the waters Sunday. The sea state will
continue to be dominated by shorter period wind generated waves
along with a light southerly swell.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...Heat Advisory...East Bay Interior Valleys and Hills,
Interior Valleys and Hills of Monterey and San Benito
Counties
SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 3 AM
&&
$$
PUBLIC FORECAST: Dykema
AVIATION: W Pi
MARINE: DRP
FIRE WEATHER: Dykema
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Area Forecast Discussion
National Weather Service Pocatello ID
211 PM MDT Sat Jul 27 2019
.SHORT TERM...Tonight through Monday.
Expect mainly isolated thunderstorms and scattered showers in the
Upper Snake River Highlands. Will be most likely in the Island
Park area south through Driggs and Victor. Isolated storms are
also possible across eastern Custer County and northern Butte
County. Much lesser chances will occur through sunset southwest of
those regions. Will have widespread dry conditions on Sunday with
some 20 to 25 mph wind gusts in the Snake River Plain. There will
be a much increased chance of showers and thunderstorms on Monday
as an upper level system moves through Idaho. Temperatures are
expected to remain above normal Sunday and Monday.
GK
.LONG TERM...Tuesday through Saturday.
The trend in the long term is hot conditions with isolated
thunderstorms expected Wednesday through Saturday. Temperatures
are expected to remain above season normals for late July and
early August. GK
&&
.AVIATION... Will have VFR conditions through Sunday. Have isolated
thunderstorms in southeast Idaho this afternoon and evening and have
VCTS at all TAF sites other than Burley and SUN. Sunday will be
clear skies across the board. Expect 10 to 15 knot upvalley
afternoon winds at PIH and IDA and SUN.
GK
&&
.FIRE WEATHER...
A shortwave trough is expected to generate iso to sct showers and
iso t-storms this afternoon across the Central Mntns, northern half
of the Snake Plain (much of Zone 410), and the MT/WY border regions,
with all activity shifting east over time. Hi-res HREF ensemble
members and HRRR offer a reasonable consensus on this scenario.
Unlike yesterday when widespread clouds prevented sfc heating and
destabilization, satellite trends reveal our region has cleared from
the Snake Plain west, and cumulus development is in progress across
the Central Mntns as we warm toward convective temps. Latest SPC
mesoanalysis shows a weak capping inversion of warmer air up around
3,000 feet has nearly mixed out, with SBCAPE (surface instability)
values now 500-1,000 J/kg north/west of the Snake Plain, so we
should be a go for storms. The overall severe wx risk is low, but
rising DCAPE (downdraft instability) values 1,000+ J/kg and still an
"inverted-V" flavor to NAM soundings due to fairly dry low-levels
suggest that storms will be capable of producing gusty/erratic
outflow winds in excess of 45 MPH, and isolated storms north of
Challis are already producing abundant lightning. These will be the
greatest fire wx threats today, especially for Zones 476/410/411. We
still feel comfortable with the iso storm coverage currently in the
forecast, so we will not be issuing a Red Flag. Storms should
largely be out of Zone 476 by 7 PM, ending everywhere by 11 PM.
Sun looks drier and breezy as a westerly zonal flow cuts off monsoon
moisture to our south. Min RHs may drop below 15% critical
thresholds in NE Zone 425, western Zone 410, and the valleys of Zone
476. Winds may also approach critical thresholds in portions of the
Snake Plain, but overall seem a bit marginal for pulling the trigger
on a Red Flag at this time. Zone 476 will be very close across the
valleys, but even here the strongest winds will focus on the mid and
upper slopes, a bit displaced from the driest low-level air in the
valleys. Will headline the near-critical conditions in the FWF, but
here too have opted against a Red Flag. No t-storm issues are
expected, but that will change Mon as another weak shortwave
approaches from the SW. This feature is impossible to clearly
identify upstream today, so confidence in how it will impact our
region is on the low side, but model consensus favors iso to sct
showers/t-storms regionwide Mon afternoon. Will hold storm coverage
at iso for now, but lightning and perhaps gusty winds could again be
risks. The trade-off will be slightly higher RH values and slightly
lower winds, all shy of critical. RHs may dry Tues/Wed, but we will
need to monitor the evolution of monsoon moisture rotating around a
high pressure ridge across the Four Corners. - KSmith/GK
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$