Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/09/18
Area Forecast Discussion
National Weather Service Albany NY
1003 PM EDT Wed Aug 8 2018
.SYNOPSIS...
Additional showers and thunderstorms are expected into this evening.
Thunderstorms will be capable of heavy rain and gusty winds.
Although mainly drier weather is expected Thursday into Friday, it
will continue to be mild. The threat for wet weather will return
over the weekend.
&&
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
Flash Flood Watch cancelled as thunderstorms have exited the
watch area...
Strongest convection will exit the mid Hudson valley and NW CT
soon but areas of light to moderate rain are still occurring
over the region. Area 00Z soundings show some instability still
across the region but the low level forcing and shear is
extremely weak. There is an exiting upper jet segment but rather
weak. Radar and satellite trends suggest that just some areas
of rain and showers in our region through the night with
coverage slowly decreasing through daybreak. There are some
breaks in the clouds to the west and depending on how many
breaks can occur outside of showers, some patchy dense fog is
possible between midnight and daybreak.
CAMS and HRRR have been a bit too aggressive with coverage and
intensity of convection in many cases through this summer and
are now trending toward less coverage and intensity through the
night. The gradual stabilization of the atmosphere through the
night should minimize chances for new convection in our region
as well. Previous AFD has a few more details and is below...
The weak surface frontal zone approaches close to midnight as
we should see a diminishing trend as loss of daytime heating and
further displacement of the jet structure. Temperatures will
likely to slowly fall into the upper 60s to lower 70s across
most of the region.
&&
.SHORT TERM /MIDNIGHT TONIGHT THROUGH FRIDAY NIGHT/...
Frontal boundary will slowly slide across the area after
midnight with a further diminishing trend in the showers. It
will still be muggy and mild with lows in the 60s and there
could be some foggy patches once again. Low level winds are
likely to decouple yet should increase a bit with frontal
passage toward sunrise Thursday.
On Thursday, short wave trough axis and associated frontal zone
will move through the area mainly in the morning hours per
ensemble of NCEP Model Suite and international guidance. A few
showers are still possible mainly to the east of the Hudson
through most of the day. However, secondary (or third) frontal
boundary was still situated across the Great Lakes and St
Lawrence Valley. A few showers may develop along this boundary
and impact northern portions of the Dacks in the afternoon.
Otherwise a mixture of sun and clouds and a little breezy
(especially when compared to lately) through the peak daylight
hours. Slightly lower dewpoints will make it feel more
comfortable as highs should once again climb to the lower-mid
80s for valley locations and 70s elsewhere.
This aforementioned frontal boundary is expected to drift
southward across the region Thursday night. There could be a
shower accompanied with this frontal passage as we will
introduce and expand the slight chance PoPs for most of the
region. Otherwise a partly cloudy to mostly clear sky expected
as we fall back into the 60s for most areas with upper 50s
across the higher terrain.
Dry weather is expected for most of Friday and there may
finally be a reduction in the humidity, with dewpoints in the
upper 50s to mid 60s. Temps will still be seasonable, with highs
in the upper 70s to mid 80s. That frontal zone may slow its
forward progress a bit as the mid and upper flow become parallel
to the surface features. We will keep the slight chance PoPs for
southern areas Friday into Friday night. Model trends are for
another short wave along the southern periphery of the upper
trough to be a little further north with the slight chance to
chance for showers into Friday night. The NAM is the most
aggressive with the ECMWF/GFS a bit more suppressed.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Good consensus from sources of guidance and ensembles for a closed
low to develop in the OH Valley and Great Lakes Saturday and Sunday
as flat downstream upper ridging sets up over the eastern U.S. The
upper low weakens and becomes an open wave by Monday and Tuesday as
the upper energy tracks east toward the northeastern U.S. The upper
energy tracks through our region in the Tuesday night through
Wednesday time frame.
There are some timing differences in sources of guidance/ensembles
but a broad consensus that the best chances for widespread rain will
be Monday afternoon through Wednesday. There could be a northern
edge of moisture and isolated to scattered showers in the mid Hudson
Valley to Berkshires and NW CT Saturday through Sunday night,
depending on how expansive the flow is around the upper low in the
OH Valley and Great Lakes and how much moisture is drawn north from
the mid Atlantic U.S. area. At the very least, a bit more clouds in
southern areas than northern areas Saturday through Monday.
There are some indications that the main area of showers and
thunderstorms lifts into areas along and north of the
Mohawk/Schoharie Valley into southern VT Tuesday night into
Wednesday. Not eliminating chances in southern areas but diminishing
to isolated by Wednesday and keeping solid chances in northern
areas. Suspect this scenario will be adjusted a number of times
between now and next week as the evolution becomes clearer.
Highs Saturday through Monday in the lower to mid 80s but cooler in
higher terrain. Highs Tuesday in the upper 70s to lower 80s but
cooler in higher elevations. Highs Wednesday in the 80s but 70s
higher terrain.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Just some isolated to scattered showers around KALB and areas to
the south. Some of the showers will approach KPSF by 02Z, so
including VCSH at KALB and KPSF through the night, when
additional showers to the west will also work into the region.
Thunderstorms to the west of KPOU are approaching there and
included IFR visibilities and MVFR ceilings in thunderstorms
between 01Z-02Z and will amend if an hour or so off on the
timing.
Additional scattered shower and isolated thunderstorms will move
into the entire area after midnight and through much of Thursday
morning and have included VCSH everywhere from about 04Z-16Z.
Outside of the showers there should be breaks in the clouds so
patchy fog could affect all the TAF sites after midnight through
daybreak. Will amend of a shower is seen tracking toward a TAF
site but nothing at this time other than VCSH. Once fog burns
off and lifts, ceilings and visibilities become VFR after about
12Z- 14Z. The showers will exit through the morning and after
16Z- 18Z, VCSH ends and clouds go to scattered.
Winds will be light from the south tonight at less than 6 Kt and
calm at times. Winds become west to northwest at 10 to 15 Kt
Thursday morning and continue through the afternoon.
Outlook...
Thursday Night: No Operational Impact. NO SIG WX.
Friday: No Operational Impact. NO SIG WX.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: Moderate Operational Impact. Chance of SHRA...TSRA.
Saturday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Sunday: Moderate Operational Impact. Chance of SHRA...TSRA.
Sunday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Monday: Moderate Operational Impact. Chance of SHRA...TSRA.
&&
.FIRE WEATHER...
Minimal fire weather concerns with recent rainfall and
additional showers with thunderstorms into this evening.
Relative humidity values will be mainly above 90 percent tonight
and generally stay above 50 percent Thursday. South to
southwest winds will be around 5 mph or less through tonight.
Winds shift and become west and northwest with speeds of 10-18
mph Thursday.
&&
.HYDROLOGY...
Flash flood watch continues to midnight for most of the region.
Showers and thunderstorms will continue into the evening hours.
Locally heavy rainfall may accompany any thunderstorm and the
wet antecedent conditions and high stream flows may easily
result in some flooding, including the potential for localized
flash flooding. Urban, poor drainage and low lying areas would
be most vulnerable, especially within the Capital Region.
Rainfall amounts will be variable due to the convective nature
of the precipitation, but local amounts over an inch are easily
possible.
Mostly dry weather may briefly return on Thursday into Friday,
but additional showers and thunderstorms are possible over the
weekend into early next week.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...BGM
NEAR TERM...BGM/NAS
SHORT TERM...Frugis/BGM
LONG TERM...NAS
AVIATION...NAS
FIRE WEATHER...Frugis/BGM
HYDROLOGY...Frugis/BGM
Area Forecast Discussion
National Weather Service La Crosse WI
633 PM CDT Wed Aug 8 2018
.SHORT TERM...(This evening through Thursday)
Issued at 255 PM CDT Wed Aug 8 2018
Latest water vapor satellite imagery showing upper level trough
over the Upper Greats Lake Region and ridging over the western
Continental United States. Shortwave trough over southern Ontario
Canada embedded in the upper level trough is producing scattered
showers and storms over northeast Minnesota and Lake Superior per
latest mosaic radar. Latest 19z surface analysis indicates ridge
over southern Iowa and producing mostly clear skies across the
forecast area.
Shortwave trough and associated surface cold front is expected to
move into central Wisconsin and central Minnesota tonight. The
08.12z GFS/NAM show surface moisture convergence and 925/850mb
moisture convergence along the front with the better pooling of
moisture/convergence over north central Wisconsin this evening. The
08.12z deterministic models/latest hi-resolution models indicate
enough vertical motion along surface front to produce scattered
showers and storms...mainly over the far northern parts of the
forecast area. The 08.12z NAM/08.17z RAP indicate around 20 knots
of 0-3km shear late this afternoon and evening across western
Wisconsin...however instability is lacking...as the NAM/RAP show
500 to 1500 j/kg surface based CAPE. A few of the storms over
north central Wisconsin could become strong with hail and gusty
winds.
Surface front remains nearly stationary over southern Wisconsin and
northern Iowa Thursday. Based on daytime heating...moisture
convergence along surface front and deterministic/hi resolution
models...scattered showers and storms are possible across
southwest Wisconsin/northeast Iowa after 18z Thursday. A few of
the storms could be strong with hail and gusty winds...as the
08.12z NAM/GFS suggest surface base CAPE of around 2000 j/kg and
0-3km shear around 20 knots.
.LONG TERM...(Thursday night through Wednesday)
Issued at 255 PM CDT Wed Aug 8 2018
GFS and EC remain lock-step with bending over the amplified west
coast ridge, leaning the axis northeast across southern Canada for
the weekend. As it does, both models have also continued to trend
toward developing a cutoff 500 mb low from a southeast moving
trough. The cutoff low could hang around the eastern great lakes/oh
river valley into Mon - which could/would bring some shower chances
to mainly eastern portions of Wisconsin.
Upper level flow then set to shift from broad ridging to more zonal
flow for the new work week, with various shortwaves tracking along
it - with potential rain threats. Disagreements with timing/location
with these features, so will let consensus detail any pcpn chance
for next week for the time being.
Temperatures look to stay summery, especially for the weekend. Highs
in the upper 80s for some locations possible/likely.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 633 PM CDT Wed Aug 8 2018
VFR conditions are expected through the TAF period. A weak cold
front slides across the TAF sites late tonight into Thursday
morning. The main impact at the TAF sites will be a wind switch to
the northwest, mainly during the late morning and afternoon on
Thursday. Did not include fog in the KLSE TAF with this issuance
given the pressure gradient staying up tonight with winds in the
500 to 1500 ft layer increasing into the 20 to 30 kt range. We may
just get into LLWS criteria tonight at KLSE, but it appears very
marginal at this time.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...DTJ
LONG TERM...Rieck
AVIATION...Wetenkamp
Area Forecast Discussion
National Weather Service Caribou ME
1025 PM EDT Wed Aug 8 2018
.SYNOPSIS...
A front will lift northward overnight while weak low pressure
tracks west of the region. A cold front will cross the region
Thursday. High pressure will build across the region Friday into
the weekend.
&&
.NEAR TERM /THROUGH THURSDAY/...
1020 PM Update...Latest forecast doing well w/the arrival of
showers back across the western areas. This area of rain is
slowly moving ene w/vigorous upper trof lifting ne. RAP
soundings show deep moisture profile through 500mbs w/PWATS
climbing to 2 inches by Thursday morning. There is good support
for heavy rainfall w/some areas possibly seeing more than an
inch of rainfall. Elevated instability is there to support
tstms. This is already in the forecast. Fog setting up along the
coast attm and decided to bring areas in along the coast and
stay w/patchy wording elsewhere. Temps will drift back into the
60s overnight as rain moves in. Adjustments were made to the
hrly temps and dewpoints to match w/the latest conditions.
Previous Discussion...
A large area of fog and stratus over the Gulf of Maine will
advect towards the coast and move northwards across the
forecast area overnight as fog and stratus. The stalled boundary
along the coast at this time will lift northward this evening
and low pressure currently in the eastern Great Lakes region
will track along the frontal boundary into the NW corner of the
state late tonight. There is potential for locally heavy rain as
instability aloft is expected after midnight and PWs will be
nearing 2 inches. This will be in association with an upper
level shortwave riding along the cyclonic side of a broader
upper trough...and the entrance to an upper lvl jet. The heavier
rainfall will taper off in northern zones Thursday morning.
Forecast QPF is maximized towards Allagash and Fort Kent with
over an inch of rain possible, but some heavier showers may also
occur towards Bangor and the Down East region. The second round
of precipitation will occur Thursday afternoon as a surface
trough lingers over the area and the broader upper trough
propagates into the area. The entrance region to another jet
will move over the forecast area Thursday afternoon. Expect
clouds and cooler temperatures during Thursday, but any breaks
in the clouds will generate instability as cooling aloft through
the day will enhance buoyancy. Dew points will remain in the
upper 60s to lower 70s through Thursday afternoon. Will just go
with thunderstorms in the afternoon rather than including
enhanced wording due to the lack of significant sfc-based
heating, but will have to keep an eye on any trends towards more
afternoon clearing that could generate more SBCAPE.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
A surface cold front will exit across the Maritimes Thursday
night while an upper level trof tracks north of the region.
Expect a chance of showers, with the slight chance of a
thunderstorm, early Thursday night. Shower chances then decrease
overnight. The upper trof exits across the Maritimes Friday,
while surface high pressure builds toward the region. Generally
expect partly/mostly sunny skies Friday, though could have the
slight chance of an afternoon shower across northern areas with
the upper trof. High pressure then builds across the region
Friday night through Saturday. Expect mostly clear skies Friday
night through early Saturday, with partly cloudy/mostly clear
skies Saturday afternoon. Temperatures will be at near normal,
to slightly above normal, levels Friday/Saturday.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
High pressure remains across the region Saturday night into
Monday with partly cloudy/mostly clear skies. Low pressure
approaches from the southwest Tuesday with increasing clouds
early, then a chance of showers. The low and a cold front cross
the region Wednesday with a chance of showers. Near normal, to
slightly above normal, level temperatures are expected Sunday
through Wednesday.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
NEAR TERM: Fog will hit BHB this evening and low clouds will
move north through the night such that all sites will be IFR
after midnight into Thursday morning. Embedded thunderstorms are
possible after midnight and again Thursday afternoon. Heavy
rainfall may occur with these storms later tonight into early
Thursday morning. Cigs will improve to MVFR by Thursday
afternoon with showers.
SHORT TERM: Occasional MVFR conditions are expected early
Thursday night with a chance of showers and possibly an isolated
thunderstorm. Generally VFR conditions are then expected Friday
into Monday.
&&
.MARINE...
NEAR TERM: Fog will continue through the period. Thunderstorms
are possible later tonight and again later Thursday afternoon.
Winds will tend to pick up Thursday afternoon ahead of a cold
front with gusts reaching 15 to 20 kts and seas increasing
towards 3 feet.
SHORT TERM: Winds/seas are expected to remain below small craft
advisory levels Thursday night through Saturday. Visibilities
will be reduced in fog and showers early Friday night, along
with the slight chance of an evening thunderstorm.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...Hewitt
Area Forecast Discussion
National Weather Service State College PA
1154 PM EDT Wed Aug 8 2018
.SYNOPSIS...
A weak cold front will move east of the region later tonight and
early tomorrow. Thursday looks like a drier day before
unsettled conditions return for the weekend into early next
week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
The most organized convection is over my SWRN zones in a region
of weak moisture convergence on the edge of a plume of high
CAPEs poking into the area from the OH Valley. The HRRR has been
quite inconsistent each hour painting a different scenario for
the convection marching across into the evening hours.
The airmass is still very humid and some of the storms are
dropping a quick 1-2 inches of rain. In areas where streams and
creeks remain high, flooding will remain a concern.
We do expect to see a gradual weakening trend as we move into
the evening and lose the heat of the afternoon.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
Still can`t rule out an passing shower or brief thunderstorm on
Thursday, but overall expect a mainly rain-free 24-hr period in
most areas. A secondary cold front will provide a better
focus/trigger for scattered T-storms on Friday. This front is
forecast to become quasi-stationary near the Mason-Dixon line
Friday night into Saturday as the upper level pattern begins to
amplify.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Models and ensembles remain in very good agreement in closing
off an upper low over the OH Valley by Sunday. This system will
slowly unwind and drift into the Northeast through midweek.
As the upper trough/closed low digs and sharpens over the east-
central U.S., expect an unsettled and wet pattern to unfold
across much of central PA through early next week. This pattern
could develop into a heavy rainfall threat considering slow
system movement, very wet antecedent conditions and prolonged
southerly fetch of deep moisture over several days. h/t WPC:
Closed lows in the summer can be underestimated in the medium
range in terms of precipitation intensity/amounts and longevity.
If this event verifies, it will likely move several long-term
climate sites up the rankings to the wettest summer (JJA) on
record.
&&
.AVIATION /04Z THURSDAY THROUGH MONDAY/...
Radar loop at 04Z shows dwindling showers over central Pa
associated with a passing cold front. Behind the front,
residual low level moisture ascending the Appalachians will
likely produce IFR cigs overnight from KBFD south through KJST,
as the model soundings and SREF probability charts suggest.
Just downwind (east) of the highest terrain, MVFR cigs appear
possible at KUNV and KAOO late tonight. Across the Susquehanna
Valley, clearing skies are expected late tonight behind the
front and a northwest breeze is likely to preclude significant
fog formation.
Low clouds banked against the spine of the Appalachians from KBFD
to KJST should mix out by midday, with a near certainty of
widespread VFR conditions across all of central Pa by afternoon.
.Outlook...
Fri...AM valley fog possible northwest Pa. Isold PM tsra
impacts possible.
Sat...Scattered showers/MVFR cigs possible, mainly southern Pa.
Sun...AM low cigs possible south central mountains. Otherwise, scattered
showers/MVFR cigs possible southern Pa.
Mon...AM low cigs possible south central mountains. Otherwise, scattered
showers/MVFR cigs possible.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...La Corte/Steinbugl
NEAR TERM...Ross/La Corte
SHORT TERM...Steinbugl
LONG TERM...Steinbugl
AVIATION...Fitzgerald
Area Forecast Discussion
National Weather Service Dodge City KS
500 PM CDT Wed Aug 8 2018
...Updated Aviation...
.SHORT TERM...(This evening through Thursday)
Issued at 116 PM CDT Wed Aug 8 2018
Widely scattered thunderstorms were already developing in north
central and west central Kansas as of 19z under a -11C 500mb
trough as it was beginning to cross western Kansas. The chance of
scattered thunderstorms will continue through the remainder of the
day and into the early evening hours across southwest Kansas as
this upper level trough passes. Strong thunderstorms capable of
producing penny size hail and wind gusts in excess of 40 mph will
be possible late day from the strongest storms. Although
thunderstorms will be possible just about anywhere across
southwest Kansas late today...the more favorable area for this
convection appears to be near the Colorado border and east of
Dodge City.
Based on the latest RAP and NAM this upper level trough will
begin to move into northern Oklahoma and central Kansas after 00z
Thursday. Skies will clear from north to south late tonight as
this upper level trough drops south into Oklahoma. A surface ridge
axis will move across western Kansas during the day on Thursday.
Dry conditions can be expected during the day on Thursday and
afternoon temperatures will likely warm back to near 90 degrees
based on the 00z Friday 900mb to 850mb temperatures forecast by
the NAM and GFS.
.LONG TERM...(Thursday night through Wednesday)
Issued at 116 PM CDT Wed Aug 8 2018
On Friday an upper level trough will drop south across western
Kansas during the day. This may result in a slight chance for
showers and thunderstorms as this upper level trough passes.
Models this morning remain in decent agreement with this upper
level trough becoming cut off from the flow early this weekend to
form a cut-off upper low over or near southwest Kansas. The GFS
and ECMWF then forecasts that this upper level system will then
slowly wobble east through the first half of next week. This will
bring our next decent chance for precipitation to western and
central Kansas along with keeping temperatures on the cool side.
Models do not handle these type of systems well so confidence is
very low on the location and track of this system during the last
half of the forecast period. Given the low confidence in the later
periods will stay close to guidance/persistence on when and where
the better chances for precipitation will occur. At this time it
appears that the current highs forecast early next week with highs
in the 80s may end up being a little on the warm side Monday or
Tuesday if we end up with a cloudy day with scattered showers.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 500 PM CDT Wed Aug 8 2018
VFR will continue through this TAF cycle. Thunderstorms near GCK
and EHA are expected to weaken quickly starting around 00z, with
the loss of daytime heating. Some convective impacts are possible
at/near GCK over the next 1-2 hours. Otherwise, a clearing sky is
expected overnight with continued light/variable winds. A weak
pressure gradient will continue to result in light winds (less
than 10 kts) on Thursday, at times variable in direction. Forecast
soundings depict a cumulus field after 18z Thu, but no convection
is expected Thursday afternoon/evening.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 63 89 65 90 / 20 10 0 20
GCK 62 89 64 88 / 20 10 10 20
EHA 62 87 63 86 / 20 10 10 30
LBL 63 89 65 88 / 20 10 10 30
HYS 65 92 66 89 / 20 0 10 10
P28 66 91 68 92 / 20 0 10 20
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Burgert
LONG TERM...Burgert
AVIATION...Turner
Area Forecast Discussion
National Weather Service Duluth MN
640 PM CDT Wed Aug 8 2018
.UPDATE...
Issued at 639 PM CDT Wed Aug 8 2018
Please see the 00Z Aviation Discussion below.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 306 PM CDT Wed Aug 8 2018
As of 3 pm, it was a warm and breezy afternoon across the
Northland with some high clouds over western Lake Superior.
Otherwise, much of the Northland had mostly sunny skies. A cold
front was working its way south across north- central Minnesota
and northwest Ontario. This front is expected to develop isolated
to scattered showers and thunderstorms from the Minnesota Iron
Range into the Arrowhead late this afternoon. There will be
increasing coverage of storms as the front moves south into
western Lake Superior and northern Wisconsin. The mesoscale,
higher resolution models are relatively good agreement with the
development and timing of these storms. Some of the storms could
be strong considering an environment of up to 2500 J/kg of MUCAPE
and 30 to 35 knots of 0 to 6 km deep layer wind shear. Much of
this wind shear is speed shear, so not thinking there will be very
strong updrafts to produce large hail, and that the primary
concerns for storms are for strong wind gusts up to 40 mph.
However, small hail of less than one inch in diameter is possible.
Clustering of the storms as they move into northern Wisconsin
could increase the wind threat because of reinforcement of the
cold front from the cold pool generated by the storms.
Smoke has made its way into the Northland from distant wildfires,
and an Air Quality Alert was issued for north-central Minnesota in
coordination with the Minnesota Pollution Control Agency. This
Alert is in effect through Thursday morning. Clear skies and
nearly calm winds will develop tonight as high pressure moves into
the region, so overnight subsistence will contribute to
concentrating some of this smoke close the surface. Thursday looks
sunny with light northerly winds, and mixing will help lift and
disperse the smoke by late Thursday morning. Expect high
temperatures in the low 80s, but cooler along the Minnesota North
Shore because of a light lake breeze. Some models, like the NAM,
SREF, Canadian, and WRFs are indicating the potential for showers
and storms along the lake breeze in the higher terrain of the
North Shore Thursday afternoon.
.LONG TERM...(Thursday night through Wednesday)
Issued at 306 PM CDT Wed Aug 8 2018
A large upper level ridge over the western CONUS will translate
eastward and keep the region dry and warm for most of the period.
With drier air filtering in and clear skies, temperatures will
warm well above climb into the 80s from Friday through Monday. On
Monday night into Tuesday, a cold front moves through the area
bringing a slight chance for thunderstorms.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 639 PM CDT Wed Aug 8 2018
Main concern over the next 6 hours are thunderstorms impacting
DLH/HYR as a cold front slides through. This activity will quickly
slide southeastward per observations and HRRR guidance.
After storms move through skies will gradually clear and winds
become light as high pressure builds in. Expect radiation fog to
develop at HIB/HYR and BRD as it did last night. Most confident in
the lowest visibilities at HYR as any showers/storms that move
through will add to ample moisture in the lower levels. Generally
expect MVFR/IFR but periods of LIFR will be possible. Do not
anticipate fog development at DLH/INL as winds should remain too
high, but it is not out of the question.
Any radiation fog should dissipate between 12Z-14Z and VFR
conditions return to all terminals. Light northwesterly winds are
expected through the rest of the TAF period.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 61 83 59 84 / 30 20 0 0
INL 56 83 56 86 / 0 0 0 0
BRD 62 83 60 85 / 0 10 0 0
HYR 59 83 56 83 / 50 10 0 10
ASX 61 82 58 84 / 60 0 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
UPDATE...WL
SHORT TERM...Grochocinski
LONG TERM...KC
AVIATION...WL
Area Forecast Discussion
National Weather Service Wilmington OH
921 PM EDT Wed Aug 8 2018
.SYNOPSIS...
Scattered showers and thunderstorms will continue across the
area through this evening as several weather disturbances shift
through the Great Lakes. Weak high pressure will build in for
Thursday bringing mostly dry and mild conditions. Another weak
frontal boundary will drop south into the Ohio Valley on Friday
with another chance of showers and storms, which will linger
into the weekend. It will remain muggy through the remainder of
the week and through the weekend.
&&
.NEAR TERM /THROUGH THURSDAY/...
The main focus for the update tonight was to adjust PoPs based
on current radar trends, mainly for the persistent band of weak
showers and storms that is now stretching from west of
Cincinnati to near Wilmington. Primarily diurnally driven, this
convection should continue to weaken, but the weak low-level
convergence never really goes away, so some isolated precipitation
cores may persist well into the overnight hours. Thus, PoPs were
extended out in time a bit from the previous forecast as well.
Still seeing some signals for fog, though not a real intense
signal for widespread dense fog. The last few HRRR runs have
started to reflect reduced visibilities in the visibility
fields. The presence of about 3-5 knots of surface westerly flow
does present an issue, and with 925mb RH forecast to remain
nearly saturated overnight through much of the CWA -- sans the
northwest where it is scouring out -- wondering if some patchy
stratus may be just as much of an issue as the fog/mist
development.
Previous discussion >
GOES East water vapor loops show a family of vorticity maxima
rotating through the Great Lakes in broad/cyclonic flow and
mid/upper level trough axis that is centered across Indiana and
western Ohio. Mosaic radar loops indicate scattered to numerous
showers and thunderstorms from Indiana through Ohio into western
PA, and especially across KY ahead of one of the stronger MCVs
over southern KY. A weak vorticity maximum over northern
Indiana was responsible for a loosely organized line of storms
moving east toward northwest and west-central Ohio. Activity
across the ILN CWA was scattered and mainly confined to the
Scioto Valley as of 19Z.
Mesoanalysis indicates that MLCAPE is ~1500 J/kg across much of
the ILN CWA owing to dewpoints that have remained in the lower
70s despite slowly veering boundary layer flow as the trough
axis aloft pushes deeper into the forecast area. Low to mid
level flow is generally modest, especially in the low levels
where bulk shear is weak. There is slightly stronger flow in the
mid/upper levels which provides effective shear values around
~25kts, about the bare minimum for storms to have any organized
updrafts. Despite weak mid level lapse rates, high delta-theta-e
with the inbound drying mid/upper level airmass has allowed for
DCAPE of around 1000 j/kg to develop downstream of the Indiana
storms this afternoon. Thus, can`t completely rule out a
strong/gusty storm through about 6 PM as the activity to the
west pushes across the Ohio border. This is a low probability
threat, but worth mentioning given the parameter space and radar
trends. Through the next 6 hours, expect the best likelihood of
storms in west-central Ohio from 4P-7P, and across the lower
Scioto Valley and northeast Kentucky 3P-8P.
&&
.SHORT TERM /THURSDAY NIGHT/...
Overnight, expect the showers/storms to rapidly decrease by mid
evening and skies will become clear. A pretty decent signal in
the forecast soundings and high resolution models fog later
tonight as the boundary layer remains quite moist, skies clear,
a rather stout inversion forms, and winds back and become light.
Thus, have inserted fog into the forecast for most areas, and
some of this could be dense. May need to consider inserting this
in the Haz Weather Outlook later this evening if surface obs
show fog getting a head start by mid-late evening. Particularly
strong signal in the HREF ensemble probability and ensemble
means from the 08.12Z runs.
A quiet Thursday is in store as weak pressure builds into the
Great Lakes, though not nearly enough to scour out any boundary
layer moisture. Thus, should see plenty of diurnal cumulus as
the boundary layer warms. Enough instability develops by mid-
afternoon that it wouldn`t be out of the realm of possibilities
for a shower or two to develop, but too low of a threat to put
in forecast at this time.
Later Thursday night, more shortwave energy in the northwesterly
flow aloft will allow a weak cold front into the Great Lakes.
Enough convergence along this front to allow for a small
shower threat later in the night, mostly along and north of
I-70.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
The beginning of the long term period will feature an upper level
ridge across the western CONUS while a mean mid level trough remains
across eastern Canada into the Great Lakes. Weak s/wv energy within
the northwest flow will accompany a weak front on Friday. This will
be the focus for some showers/storms.
For the weekend and into early next week, the upper level ridge out
west is forecast to amplify as it pokes northeast into south central
Canada. The subsequent downstream result will be a developing closed
low across the Great Lakes and Ohio Valley. the boundary from Friday
will linger into Saturday, then as we head into Sunday/Monday, a
weak low will become perturbed along it as the upper level low
closes. Chances of showers/storms will continue with all these
weather features remaining in our region.
The upper closed low may get a "kicker" from the west to nudge it
east as we head into Tuesday. However, it now looks that it may be a
bit slower to move out, so will have to hold on to a chance of
showers/storms across the east.
By Wednesday, upper level flow pattern is expected to open up and
become more progressive. By this time, a more bonafide weather
system may move into the Ohio Valley, which will continue the
persistent chances of showers/storms in the forecast.
As for temperatures, highs in the lower to mid 80s will be common on
Friday, followed by upper 70s to lower 80s for the weekend into
Monday. A slight rebound should occur by Tuesday/Wednesday. Lows
will be mainly in the 60s.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
A few showers and thunderstorms will remain possible at the very
beginning of the TAF period, but this threat should diminish
quickly, leaving dry conditions through the rest of the
forecast. There does appear to be the potential for some fog
and/or stratus development later in the overnight period,
especially at KCMH/KLCK/KILN. Will continue the previous
forecast of MVFR conditions everywhere (with IFR fog at KLUK)
but recent data suggests IFR ceilings may develop, at least in
patches, during the early morning hours.
Dry and VFR conditions are expected on Thursday, with generally
light westerly winds.
OUTLOOK...Thunderstorms are possible at times from Friday
through Monday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Binau
NEAR TERM...Binau/Hatzos
SHORT TERM...Binau
LONG TERM...Hickman
AVIATION...Hatzos
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1159 PM EDT Wed Aug 8 2018
.UPDATE...
Issued at 1159 PM EDT WED AUG 8 2018
The fog and/or low stratus is setting into to some locations
tonight based on obs and GOES-16 data. Given this trend added
patchy to areas of dense fog to the forecast. Otherwise, this was
a minor update to add in the latest obs and trends.
UPDATE Issued at 1028 PM EDT WED AUG 8 2018
The latest radar trends reveal little to any rain shower activity
in eastern Kentucky. We are still watching some convection
upstream across portions of far northern Kentucky into portions
Ohio this evening. This continues to show signs of weakening, but
did add a isolated POP across Fleming county later tonight in
case this convection doesn`t wane. Some of the hires data does
bring a band of showers making it into the Bluegrass toward dawn,
and this could be related to the near by frontal boundary and
more favorable jet region. However, confidence remains low at
this point on if or when this will actually occur. Given this will
keep things dry for now in this update. Did update temperatures,
dewpoints and winds to better match the latest obs and trends as
well.
UPDATE Issued at 712 PM EDT WED AUG 8 2018
The latest scans of the WSR-88D radar indicate much of the shower
and thunderstorm activity has waned this evening. Given this did
update the POPs to better handle this trend in areal coverage.
This seemed to be handled well by the latest run of the HRRR TLE
and therefore blended POPs in that direction. We still have a
isolated storm in the east, so will keep the mention of thunder
going for a little while longer. There is some upstream convection
across portions of Indiana and Ohio, but the short term guidance
trends have this activity decaying through the later evening
hours before making it into northern Kentucky. This seems
reasonable given the area has been worked over by earlier
convection. Also updated the grids to better deal with the latest
obs and trends.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 440 PM EDT WED AUG 8 2018
19z sfc analysis shows low pressure to the north with a meso high
located over the Cumberland Valley. This bubble of higher pressure
is in the wake of some strong to severe thunderstorms that moved
east earlier in the afternoon and associated with a developed cold
pool. Additional scattered storms are found further northeast of
the Cumberland Valley and a broken line moving east through the
Bluegrass area. With the strong convection around CDO covers much
of the CWA with the exception of far southeast Pike County. Also,
the swirl of the MCV responsible for pushing the storms shows up
well on the GOES satellite as it curls east over Monroe County.
Temperatures vary across the area from the mid 80s north and east
of the storms to the low 70s in the rains. Dewpoints remain very
high in the low to mid 70s most places with winds generally
southwest at 5 to 10 mph - away from any storms. The storms and
training cells have brought excessive rains to parts of the area
as well with a couple of flash flood warnings and small stream
advisories issued. Gusty winds with the storms have brought down a
few trees across the Cumberland Valley with mesonet reports of
gusts pushing 40 mph in our southern tier.
The models are in good agreement aloft through the short term
portion of the forecast. They all depict the broad Great Lakes
trough moving east and north into eastern Canada tonight and
Thursday. South of this, flatter flow will be found over Kentucky
during this transition with some weak mid level energy passing
through the area west to east but not much in the way of height
falls or rises during this time. With the good model agreement
have favored a general blend with a strong lean toward the CAMs
depiction for the near term.
Sensible weather will feature the main batch of storms moving east
out of the southern parts of the area early this evening with a
downward trend in the convection after sunset. An approaching
cold front will maintain a small chance for mainly showers through
the night but most locations will be dry per the latest HRRR.
Plenty of clouds should limit the worse of the fog formation to
the river valleys again tonight. The cold front never really
clears the area on Thursday so that a few showers and storms will
be possible, mainly along and south of the Hal Rogers Parkway.
This boundary may stay active into Thursday night with showers
possible in the far south while fog develops again in the river
valleys toward dawn Friday. Temperatures will be near normal for
highs on Thursday with lows warmer and more muggy than normal each
night.
Used the CONSShort and ShortBlend as the starting point for all
the grids. Made only minor point based adjustments for
temperatures through the period given the level of moisture
around. As for PoPs, did tack them toward the aggregate CAMs
scenarios in the near term. Also, made the values a bit higher in
the south on Thursday and Thursday night to account for the
proximity of a stalled front.
.LONG TERM...(Friday through Wednesday)
Issued at 325 PM EDT WED AUG 8 2018
Fairly unsettled pattern with a mid level trough in place will
continue through the upcoming weekend and into early next week.
No organized systems are expected to impact the region, but
instability and moisture should be sufficient to yield
afternoon/evening shower and storm chances. A lull still looks
possible late Tuesday next week, but any dry period will be short
lived, as another shortwave trough moves into the region by
Wednesday. Fortunately, lack of better shear will keep severe
threat fairly limited into next week. Warm weather will continue
with highs in the 80s and lows in the 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 742 PM EDT WED AUG 8 2018
Much of the earlier convection has now relented and even a few
sites now seeing only high clouds this evening. We should
continue to see mid to high level clouds through the evening at
most sites. We have seen some low clouds at JKL, but this is due
to some midslope fog driving up out of the valley below. Then
guidance and the forecast soundings indicate the potential for
some low stratus and/or fog tonight at the TAF sites, with IFR at
least looking like a good bet at most locations given the ample
low level moisture in place. These low clouds and fog will lift
around 13 to 14Z on Thursday and we will be left with MVFR to VFR
conditions. The winds will remain light through the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...DJ
SHORT TERM...GREIF
LONG TERM...KAS
AVIATION...DJ
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
847 PM EDT Wed Aug 8 2018
.SYNOPSIS...
A cold front approaching from the Ohio Valley will cross the
Mid-Atlantic tonight. Weak high pressure will follow briefly
Thursday into Friday before a slow moving area of low pressure
brings a return to unsettled weather this weekend into early
next week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Initial round of showers and thunderstorms, initiated by an
MCV, crossed central Virginia. Attention now turns to the
Maryland/Pennsylvania border, where thunderstorms have support
from a trough axis/lower heights and an approaching upper jet.
These thunderstorms in an environment characterized by 25-30 kt
of effective bulk shear. While they may be leaving the shear
behind, instability is better, evidenced by almost 1500 J/kg
MLCAPE from the 00z LWX RAOB.
Evolution is a bit uncertain as CAMs have been inconsistent.
However, the favored solution based on current initialization
and persistency is somewhere between the HRRR and HREF (ARW
core). This solution would take storms at least across northern
Maryland, and perhaps propagate as far south as metro Washington
DC. This focus area should be over/east of the Bay somewhere
around 11pm.
Subtle dry advection begins aloft late during the overnight,
and if we break out of the clouds before daybreak than fog will
develop.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
A weak area of high pressure will move from the Midwest to
Tennessee Valley and nose into the region Thursday as an upper
trough axis passes overhead. With the trough nearby, scattered
to broken clouds are expected, along with the possibility of a
pop up shower (mainly over the higher terrain). It will be a
couple degrees cooler (both temps and dew points) but not by
much. Heat index values should peak in the low 90s as opposed to
near 100 like recent days.
Additional shortwave energy rotates around troughing over
southeastern Canada Thursday night into Friday, with additional
pop up showers possible Friday afternoon and evening (mainly
near and west of the Blue Ridge).
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Aforementioned upper-level trough will build into the region
from Canada and New England Saturday. The 500mb trough is
forecast to become a cut off low sometime later Saturday or
early Sunday. The cut off low is expected to linger over the
region through Monday. Starting on Saturday, showers and
thunderstorms will be likely starting as scattered in nature,
becoming more widespread by Sunday. The position of the cut off
low to our northwest will act to create a south to southwesterly
flow which will transport tropical moisture into our region.
This will lead to precipitable water values near the two inch
mark. The presence of high moisture levels along with the upper
level trough to the west will create a environment favorable for
repeated rounds of heavy showers and thunderstorms, which could
ultimately result in more flooding issues. Temperatures this
weekend will be in the upper 70s to mid 80s with light winds out
of the south.
Monday into Tuesday, the cut off low will shift eastward over
our region. Precipitable water values are forecast to reach
above the two inch mark for most of our region on Monday. This
will lead to conditions favoring a potential large precipitation
event which increases the potential for flooding. The cut off
low is forecast to move north of our region on Tuesday and start
to shift out of our region by Tuesday evening into Wednesday.
The surface wind flow is expected to become westerly on Tuesday
which will help to limit the moisture levels and the
precipitation potential. Scattered showers and storms will still
be potential on Tuesday due to the upper level low sitting near
the region.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
Thunderstorms have been dancing around the terminals without any
direct impact. Do not have confidence in any airfield being
directly affected this evening either. Have an hour or two
TEMPOs when something becomes more apparent.
Patchy fog possible tonight, but potential for clouds to hang
around mitigating this threat. Kept TAFs MVFR for MRB/CHO where
fog is most likely. Light and variable winds expected tonight.
Mainly VFR expected Thu-Fri as weak high pressure builds. Pop
up shower can`t be ruled out each aft near MRB/CHO. Patchy fog
possible at night. A brief and weak surge behind the cold front
Thu AM likely results in 16-20 kt gusts for a few hrs 13-17Z.
Otherwise NW flow AOB 10 kts.
On Saturday, an upper-level low will cut off and be located to
our northwest. Skies should be mostly cloudy with scattered
showers and storms. Winds start out northerly and then become
southerly later on in the day. Sub-VFR condtions are possible.
Sunday, showers and storms will become more widespread with winds
mainly out of the south. Skies will be mostly cloudy with cloud
bases and visibilities dropping below VFR levels within showers and
storms.
&&
.MARINE...
Showers and thunderstorms are likely over the waters this
evening ahead of a cold front approaching from the Ohio Valley
Some storms may produce wind gusts in excess of 30 knots as
well as frequent lightning and reduced visibility in heavy rain.
Storms should weaken by late this evening.
A brief period of gusts to around 20 knots is expected Thursday
morning in a weak pressure surge behind the departing cold
front. Sub SCA winds and mainly dry weather is expected
otherwise Thursday into Friday as weak high pressure builds.
Scattered showers and storms will be possible with light winds
starting out as northerly and becoming southerly by the end of
the day on Saturday.
Showers and storms will become more widespread on Sunday. Winds will
remain generally light out of the south.
&&
.TIDES/COASTAL FLOODING...
Elevated water levels are expected through Thursday morning.
This is due to a southerly component to the surface flow. However,
the flow is light so sensitive areas are only expected to reach
caution stage at this time.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 6 AM to 2 PM EDT Thursday for
ANZ530>543.
&&
$$
SYNOPSIS...DHOF
NEAR TERM...HTS/DHOF
SHORT TERM...DHOF
LONG TERM...JMG
AVIATION...HTS/DHOF/JMG
MARINE...DHOF/JMG
TIDES/COASTAL FLOODING...DHOF
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1052 PM CDT Wed Aug 8 2018
.UPDATE...
Issued at 1047 PM CDT Wed Aug 8 2018
Updated to include 06z aviation discussion below.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 300 PM CDT Wed Aug 8 2018
The short term concern remains extent of any convection late
afternoon and overnight. Also, the possibility of more fog over
the eastern area late.
Latest SPC mesoanalysis continue to trend around 1500 J/kg MLCAPE
developing after 21z over west central WI. Surface winds remain
more southwest and surface convergence remains weak out ahead of
the incoming front. 12z HIRES cams continued to drop south widely
scattered/isolated convection over west central WI into the
evening. Still, the marginal severe risks remains if convection
does develop. The 17z HRRR is slower with its frontal progression
and clips Rusk Co. with a shower. Models have been hinting that as
the front sags southeast, some mid level moisture remains and
affect east central/south central MN after midnight. May see some
ACCAS associated with the front, and perhaps an isolated
shower/storm. Will leave this out for now, as confidence is low if
this will be something that develops QPF.
Fog is possible later tonight over the river valleys in western
Wisconsin. Therefore, will continue to forecast patchy fog in this
area. Still looks warm Thursday afternoon, with little in the way
of any significant cooling behind it.
.LONG TERM...(Thursday night through Wednesday)
Issued at 310 PM CDT Wed Aug 8 2018
The extended period continues to advertise dry and warm conditions
through early next week as a ridge of high pressure expands, and
dominates the Northern Plains, and Upper Midwest. Initially,
northwest flow aloft could support an isolated shower or storm
Thursday evening. However, due to the relatively dry atmosphere,
will leave the forecast dry. Past Thursday night, as the ridge of
high pressure expands across the region, very dry mid-levels will
support the dry forecast through Monday.
Slowly, the ridge will begin to flatten early next as a series of
short waves move inland across the Pacific Northwest, and move
eastward. As the ridge flattens, and more zonal flow develops
aloft, there will be an increasing chance of precipitation. The
best chance of anything remotely possible, or with scattered
activity, will occur around Tuesday/Wednesday of next week as a
frontal boundary moves south across the region.
The highest temperatures will occur across the high plains of
Montana, North and South Dakota where the 925/850mb thermal ridge
will develop. Further to the east, the highest temperatures will
occur in west central/northwest Minnesota where again, the best
chance of the thermal ridge develops before the upper ridge
begins to flatten out next week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1047 PM CDT Wed Aug 8 2018
VFR conditions expected to prevail at all TAF sites with only
FEW/SCT mid-to-high level clouds during this TAF period. The main
exception will be pre-dawn ground fog mainly in western WI
(affecting KRNH-KEAU), which will likely temporarily bring
visibilities into MVFR range but IFR is possible.
KMSP...No significant weather impacts expected.
/OUTLOOK FOR KMSP/
Fri...VFR. Wind NW 5 kt or less.
Sat...VFR. Wind light and variable.
Sun...VFR. Wind S 5 kt or less.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&
$$
UPDATE...JPC
SHORT TERM...DWE
LONG TERM...JLT
AVIATION...JPC
Area Forecast Discussion
National Weather Service Missoula MT
244 PM MDT Wed Aug 8 2018
..Near Record Heat Expected Thursday and Friday...
.DISCUSSION...The upper level ridge continues to build over the
Northern Rockies. Wildfire smoke depicted in current satellite
imagery has more of a easterly trajectory rather than the
northwest to southeast track from yesterday. As fires become more
active this evening, this easterly wind will carry more smoke
towards us. The biggest quandary is how much smoke will we
accumulate by Friday as that will determine how hot we will get.
Simulated smoke from the HRRR model suggests that more smoke from
northern CA and Oregon will make it over central Idaho later today
into tonight, and smoke from Washington State will make a b-line
towards Lincoln County and Glacier National Park.
We continue to expect near record high temperatures on Thursday
and Friday. The last time Missoula saw 100 or greater in August
was back in 2012. The last time Kalispell, Eureka, Thompson Falls
and Orofino, Idaho saw the century mark in August was back in
2015. Heat exhaustion is likely during strenuous outdoor activity
during hot weather, so plan on being in a cool location that has
air conditioning if possible.
Gusty westerly winds are expected on Saturday especially across
western Montana as a relatively dry cold front moves through.
Temperatures will cool to more seasonable levels and remain there
Sunday through early next week.
&&
.AVIATION...VFR conditions under clear skies are expected in the
next 24 hours, though increased smoke/haze could reduce mountain
visibility. Density altitudes will increase during peak heating
hours.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Fire Weather Watch from Friday afternoon through Saturday
evening Bitterroot...Deerlodge/West Beaverhead...East
Beaverhead...East Lolo...Flathead/Glacier Park...Salish and
Kootenai Reservation.
Heat Advisory from 3 PM Thursday to 9 PM MDT Friday
Flathead/Mission Valleys...Kootenai/Cabinet Region...Lower
Clark Fork Region...Missoula/Bitterroot Valleys...
Potomac/Seeley Lake Region...West Glacier Region.
Fire Weather Watch from Friday afternoon through Saturday
evening Kootenai...West Lolo.
ID...Fire Weather Watch from Friday morning through Saturday evening
Clearwater/Nez Perce...Palouse/Hells Canyon.
Heat Advisory until 8 PM PDT Friday Lower Hells Canyon/Salmon
River Region...Northern Clearwater Mountains...
Orofino/Grangeville Region.
&&
$$
Area Forecast Discussion
National Weather Service San Francisco Bay Area
858 PM PDT Wed Aug 8 2018
.SYNOPSIS...High pressure will continue to build over California
through Thursday and result in very warm to hot conditions across
the interior. Meanwhile, seasonably mild conditions will continue
near the coast due to a persistent shallow marine layer and
moderate onshore flow. Temperatures will then cool slightly for
inland areas over the upcoming weekend as high pressure weakens.
&&
.DISCUSSION...As of 8:55 PM PDT Wednesday...Most of our area
experienced warmer temperatures today, with afternoon highs
anywhere from a few degrees warmer than yesterday to as much as 15
degrees warmer. Today`s warming was due to strengthening of an
upper ridge centered over Nevada, as well as slightly reduced
onshore flow. Highs today were close to seasonal averages near the
coast and bays and in the coastal valleys, but anywhere from 5 to
10 degrees warmer than normal for the inland valleys.
Smoky skies prevailed across our region today. Latest HRRR smoke
drift forecast indicates little change in smoke concentration
across our area through Thursday morning, but then improving air
quality by Thursday afternoon as transport winds turn to the west
and southwest.
No significant changes are forecast through the end of the work
week. Very warm to hot conditions will continue in the inland
valleys and hills as strong high pressure persists across the
West. Coastal areas are expected to warm slightly over the next
two days, but persistent onshore flow will keep coastal
temperatures mild. The GFS forecasts temperatures to be warmest
on Thursday, while the ECMWF indicates temperatures will be
warmest on Friday. The models agree that cooling will occur over
the weekend as an upper trough, currently located several hundred
miles off the West Coast, lifts to the northeast and moves inland
across the Pacific Northwest on Friday night and Saturday.
Hurricane John, currently centered west of the southern tip of the
Baja Peninsula, is forecast to continue tracking to the northwest
through the rest of the week and into the weekend. Southerly flow
aloft is forecast to draw moisture from John northward and across
California later in the week. The NAM, which has been the most
bullish of the models in advecting this tropical moisture
northward, has been trending slightly drier and slower. Moisture
in the mid/upper levels is now forecast to increase across the Bay
Area Friday afternoon and evening. Although the NAM has been
trending somewhat drier, the model continues to forecast
reasonably impressive mid level instability with the incoming
tropical moisture. For example, the 00Z NAM forecasts modified
Total Totals of nearly 40 across the central portion of the SF Bay
Area on Friday evening. So there remains some concern that we
could see high-based convection develop later on Friday. However,
the GFS and ECMWF continue to forecast less in the way of moisture
and instability. And, as was mentioned in previous discussions,
the NAM has generally been too eager to forecast convective
precipitation potential this summer. So, will continue to leave
any mention of thunderstorms out of the forecast and continue to
monitor the situation closely. Also, it should be noted that both
the GFS and ECMWF forecast the highest mid/upper level relative
humidity values (from remnants of John) to reach our area late in
the weekend and into early next week. So even if high-based
convection doesn`t develop late this week, the potential for
thunderstorms may continue into early next week.
&&
.AVIATION...as of 04:35 PM PDT Wednesday...For 00z tafs. Marine
layer remains around 1000 ft with stratus along the coast. Expect
HZ/FU from wildfires near and far to continue to create slantwise
vis issues at terminals. Stratus is expected to return this
evening along the Monterey coast before moving in elsewhere
overnight. Patchy fog will be possible along the coast early
tomorrow morning. Breezy onshore winds will diminish this evening
and overnight before increasing again tomorrow afternoon.
Vicinity of KSFO...VFR with gusty westerly winds to 25 kt will
continue into the evening before winds lessen to around 10-15 kt.
Expecting IFR cigs to return overnight and last into the morning.
Slantwise vis issues will continue to be a concern due to wildfire
smoke.
SFO Bridge Approach...Similar to KSFO
Monterey Bay Terminals...VFR through this evening before an early
return of stratus. LIFR/IFR conditions will persist overnight with
patchy fog and drizzle possible into sunrise. Generally light
winds through the period.
&&
.FIRE WEATHER...as of 2:33 PM PDT Wednesday...The 12Z models did
not add any confidence to the upcoming forecast challenge. The
NAM and local WRF model continue to show an increase in moisture
(associated with Hurricane John) and instability moving over the
northern portion of the region late Thursday into Friday. Simply
put, if you`re looking for a set up that would result in high-
based convection the NAM/WRF shows it. Greatest potential would be
Friday afternoon. However, confidence remains low as the GFS and
ECMWF are less robust with both moisture and instability over our
region during this time frame. Therefore, this is a non-zero
event. We`ll continue to monitor this very closely as any
convection would have big impacts.
&&
.MARINE...As of 8:44 PM PDT Wednesday...Northwest winds will
diminish overnight and tomorrow across the coastal waters. Locally
gusty winds will continue along the immediate coast north of
Point Reyes, from the Coast Dairies to Pigeon Point, and south of
Point Sur. A long period southerly swell generated by Hurricane
John will arrive late Thursday and is expected to run parallel to
the coastline.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...Pt Arena to Pt Reyes 0-10 nm until 3 AM
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 AM
&&
$$
PUBLIC FORECAST: Dykema
AVIATION: AS
MARINE: AS
FIRE WEATHER: MM
Visit us at www.weather.gov/sanfrancisco
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayarea
Area Forecast Discussion
National Weather Service Phoenix AZ
220 PM MST Wed Aug 8 2018
&&
.SYNOPSIS...
A shift towards a more favorable easterly flow aloft along with an
increase in available moisture is expected to lead to a more active
monsoon pattern through the upcoming weekend. Thursday looks likely
to be the most active day weatherwise, when thunderstorms could
approach severe limits, with very strong winds, areas of blowing
dust, and locally heavy rain possible. Some reduction in convective
activity is possible early next week as somewhat drier air moves
into the region.
&&
.DISCUSSION...
A return to a more active monsoon pattern still looks likely, as
moisture surges up the Gulf of California continue to raise sfc
dewpoints across the region. Dewpoints as high as 80 degrees were
observed across parts of SE CA this morning, likely elevated
somewhat by a moisture boast that was aided by Hurricane John as is
moves northwestward off the Baja coast. In spite of this moisture-
rich environment, convective activity looks like it will be a bit
subdued across the lower elevations of our cwa today. The latest
forecast sounding for the Phoenix area continues to show a rather
strong cap just above the PBL, which will likely make it very hard
for thunderstorms to survive into the lower elevations of south-
central AZ. This idea continues to be supported by the high-res HRRR
and U of A WRF-NAM models. Still, it is likely that at least a few
storms will make their way into the greater Phoenix area this
evening, with many areas seeing gusty outflow winds. The increase in
moisture and cloud cover is expected to keep high temperatures much
closer to normal than what we have been seeing the last several days.
Thursday looks like it could be quite active weatherwise. The
combination of modest cooling aloft (500mb temps falling into the -
8C to -10C range), a bit more mid-level shear (Bulk Shear values in
the 20-25 knot range), and the disappearance of the cap as the
sounding becomes well-mixed will likely allow much of the storm
activity that does develop over the Rim Country and over SE AZ to
make its way into the lower desert. Both the HRRR and the U of A WRF
model suites show scattered-numerous storms moving into the greater
Phoenix area tomorrow evening. SPC already has much of central and
southern AZ in a MRGL risk area for severe storms for Thursday.
Depending on how active things turn out on Thursday, Friday and
possible Saturday will likely be a bit less active due to the
atmosphere being worked over by tomorrow`s storm activity. However,
the activity is still expected to remain at above-average levels,
with the main threat being locally heavy rain/flash flooding due to
slower storm motion and ample available moisture.
A reduction in convective activity looks possible from Sunday into
early next week as somewhat drier air is imported into the region,
with temperatures perhaps warming up a bit as well.
flooding.
&&
.AVIATION...
South-Central Arizona including KPHX, KIWA, and KSDL:
There are still several aviation weather concerns through tonight.
First, the hazy conditions that have created slantwise visibility
issues is slowly improving, and should continue to do so through
the late morning. Westerly winds will take hold by late
morning/early afternoon with a few occasional gusts. However,
there is a strong likelihood of thunderstorms forming over the
Rim north and east of Phoenix and those should start to develop
around 21Z. These storms will probably produce strong outflow
winds from the east/northeast with gusts up to 25-35 kts. The
timing of this wind shift is uncertain but will most likely reach
KPHX by 3Z. In addition, these winds may also loft blowing dust
that could temporarily reduce visibility and create new slantwise
visibility concerns. During this time, thunderstorms are possible
in the terminal area, especially for locations east of KPHX.
However, there is enough doubt as to whether or not storms reach
Sky Harbor so any mention of VCTS is currently left out of the
TAF.
Southeast California/Southwest Arizona including KIPL and KBLH:
There are no aviation weather concerns through this evening as
winds will remain light and maintain a south/southeast direction.
The storm activity should remain well to the east but increased
cloudiness tomorrow is likely.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Friday through Tuesday:
Significant moisture will affect the region at least through
Saturday and likely into early next week. This will result in day
to day thunderstorm chances through the period. Storms are
expected to be most prevalent over the higher terrain north and
east of Phoenix but even lower elevations will have a shot at
precipitation each afternoon. Minimum humidities will end up
between 20 to 30 percent over the deserts each day following fair
to good overnight recoveries. Apart from thunderstorms, winds will
be light except for typical afternoon and evening upslope
breeziness. Temperatures each day will remain at or just below
seasonal normals although portions of the south-central deserts
may drop to near 100 Thursday into Saturday as thicker clouds and
moisture affect the region.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter reports may be needed later this week.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Percha
AVIATION...Deemer
FIRE WEATHER...Kuhlman
Area Forecast Discussion
National Weather Service San Diego CA
822 PM PDT Wed Aug 8 2018
.SYNOPSIS...
Hot and humid weather will continue through Thursday. Monsoon
moisture will bring isolated to scattered thunderstorms to the
mountains and possibly in deserts each afternoon through Friday.
A return of onshore flow and drying of the monsoonal moisture is
expected for the weekend through early next week with high
temperatures returning to near to slightly above average and low
temperatures remaining above average.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
...Update...
Smoke from the Holy Fire has spread south and southwestward this
evening with the smokey skies reaching throughout Orange County
and into far northern San Diego County. Have adjusted the forecast
based on this trend to add smoke to these areas. Lots of smoke
will continue across Orange County to the IE to the high deserts
on Thursday.
The other update made was to increase POPS rather drastically for
Thursday. Hi-res models are in consensus in showing an up-tick in
convection over the mountains Thursday afternoon. Monsoonal
moisture will be in place. East wind flow does pick up aloft,
which could send cells into the inland valleys. Have increased
POPS across these areas. HRRR and WRF show weakening cells moving
along the border across southern San Diego County tomorrow
afternoon nearing the coast. Have placed low POPS there to account
for this possibility.
Friday could be active but questionable, so at this point did not
make changes, but POPS may need to be increased for Friday.
Midshift can assess with the 00Z model runs.
...Previous Discussion (Issued at 145 PM PDT Wed Aug 8 2018)...
A bubble of warm monsoon air pushed into coastal areas this
morning, allowing temperatures to rise even more than they did
yesterday. For a while, temps were the same in San Diego,
Riverside and Palm Springs with a humid monsoony air mass settling
over the region and a smoke shield shading the Inland Empire. A
heat advisory was issued for this afternoon through Thursday since
temps will be very similar Thursday. Cumulus and even a couple of
cells of cumulonimbus (thunderstorm) clouds were getting going
around San Gorgonio Peak and south of the border. Smoky skies
from the Holy Fire on Santiago Peak will continue in the
northwest Inland Empire. Hurricane John is forecast to weaken
from hurricane today to tropical storm on Thursday. The main
impact on us from John will be that he will help the southeast
monsoon flow to continue through about Friday. The monsoon
moisture deepens Thursday into Friday for a better chance of
thunderstorms mainly in the mountains and mainly in the
afternoons. The deeper moisture will increase the potential for
isolated flash floods. Some model guidance is hinting
intermittently that some nocturnal wave or outflow from Arizona
thunderstorms could move into our region during the nights tonight
and Thursday night. This keeps our attention for the possibility
of nocturnal showers or thunderstorms and even west of the
mountains. However, latest guidance has downplayed that scenario,
but its still on our (ahem) radar. The easterly flow will keep
temps up Thursday, as well as the possibility of a few
thunderstorms drifting into inland valleys. Later Friday and
Saturday the flow turns more westerly, which will decrease the
monsoon moisture and thunderstorm chances over the weekend.
Temperatures will decrease over the same time period, but max
temps in most areas will remain a couple degrees above average.
Still, near normal will feel like relief. In addition, some
coastal low clouds should be able to develop and survive the
nights. This will be the case Saturday through Monday as we get a
break from extreme heat and thunderstorms. For Tuesday and
beyond, model guidance had featured a decent warming trend and
monsoon push, but the 12Z models have backed off that a bit. Now
it appears a very minor warming trend and no thunderstorms until
Wednesday or Thursday.
&&
.AVIATION...
090300Z...Coasts/Valleys...Very patchy stratus will develop late
tonight along the coast with local cigs 600-900 ft MSL and local vis
2-4 miles over higher coastal terrain. Aerodromes SAN/CRQ could have
tempo cigs between 10Z and 15Z Thu. Most areas will clear by 15Z
Thu. Smoke from the Holy Fire will create 5000 ft ceilings at times,
and reduces VIS for some areas.
Mountains/Deserts...Scattered thunderstorms will occur over the
mountains and deserts Thursday afternoon and evening, with cloud
bases around 7000 ft MSL and tops to 45000 ft MSL, strong
up/downdrafts and surface gusts to 45 kt. Otherwise, patchy smoke
from the Holy Fire at times.
&&
.MARINE...
No hazardous marine weather is expected through Monday.
&&
.BEACHES...
Evening high tides will rise to around 7 ft Thursday through
Saturday. In addition, south swells generated from Hurricane John
will move into the coastal waters Thursday and continue through
the weekend. The combination of high tides and increasing surf of 3-
6 ft (mainly south/southwest facing beaches) will likely cause minor
coastal flooding during the late afternoon and evening each of these
days. Large tidal swings and elevated surf will also generate strong
rip currents.
&&
.FIRE WEATHER...
Higher humidity and continued heat are expected through Thursday.
While the heat will increase fire potential, the higher humidity
will mitigate the threat. Isolated thunderstorms are expected
in and near the mountains this afternoon, with scattered
thunderstorms Thursday afternoon and early evening for the
mountains and portions of the deserts.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT Thursday for Orange County Inland
Areas-San Bernardino and Riverside County Valleys-The
Inland Empire-San Diego County Valleys-Santa Ana Mountains
and Foothills.
Beach Hazards Statement from Thursday evening through Saturday
evening for Orange County Coastal Areas-San Diego County
Coastal Areas.
PZ...NONE.
&&
$$
PUBLIC...Gregoria (Update)/MM (Prev Discussion)
AVIATION/MARINE...JJT
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
825 PM EDT Wed Aug 8 2018
.UPDATE...Last of the storms were northeast of Lakeland this
evening. An area of light stratiform rain has formed from Lakeland
to Venice and the HRRR model moves it northwest into Tampa Bay.
Radar showed the light rain diminishing near Sarasota and developing
between Ruskin and Bartow. Will tweak rain type and POPs through 03Z
then no changes to going forecast.
&&
.AVIATION...
Leading edge of VFR stratiform light rain from KSRQ-KLAL moving
northwest. Scattered sea breeze thunderstorms to develop after 18z
along coast then moves inland.
&&
.MARINE...
High pressure remains across coastal waters. Winds will shift from
southerly to west/southwest Thursday, remaining so through the
weekend. Winds look to remain 10 knots or less and seas 2 feet or
less. Scattered marine showers and storms may result in locally
higher winds and seas.
&&
.FIRE WEATHER...
Adequate moisture will remain in place to prevent low
humidities. This and daily rain chances will prevent any
fire weather concerns.
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...Beach Hazards Statement through Thursday evening for
Coastal Charlotte-Coastal Lee-Coastal Manatee-Coastal
Sarasota.
Gulf waters...None.
&&
$$
Update/Aviation/Marine...72/Noah
Area Forecast Discussion
National Weather Service Tucson AZ
320 PM MST Wed Aug 8 2018
.SYNOPSIS...Abundant moisture and favorable flow will provide an
active period for thunderstorms with locally heavy rainfall at times
into early next week. Daytime temperatures will also trend closer to
seasonal averages.
&&
.DISCUSSION...As expected, our first storms have popped over the
White and Chiricahua Mountains this afternoon where the most
clearing has occurred thus far. Visible satellite trends also
suggest cu fields trying to develop vertically over the Pinaleno and
Galiuro Mountains. The cloud shield associated with this morning`s
deteriorating MCC continues to dissipate for locations across Pima,
Pinal and Santa Cruz Counties. In particular, the dense cirrostratus
has really limited daytime heating with Tucson struggling to get out
of the 80`s, though the high today so far is 90 degrees as of 8/21Z.
Nogales has not hit 85 as of yet, but notable clearing from south to
north this last hour may still allow that to occur. With the lack of
sufficient heating from Tucson westward, storms rolling through the
metro will likely be dependent on any outflows from convection
developing on the Mogollon rim. If this occurs, the best chance for
measurable precip at KTUS looks to be between 9/02Z and 9/07Z, with
the potential for some blowing dust to occur during that time period
as well.
Storms today are feeding off plentiful moisture of 1-1.5+ inches
PWAT via satellite estimates. Additionally, mid-level easterly flow
is quite strong with speeds of 25-35 kts. Upper-level flow however
has a westerly component, and so far anvils are being sheared off
toward the east as storms try to propagate westward off the terrain.
This didn`t seem to be too much of an issue for storm development
across northern Chihuahua and Sonora though, where a clustering of
storms looks to be the beginning of yet another MCS. Will have to
keep an eye on these storms into the evening since their evolution
may have an effect on tomorrow`s weather across southeast Arizona.
The CAMs including the HRRR and various local WRFs are in pretty
good agreement, developing the strongest convection early this
evening and sustaining through about midnight. Given the
aforementioned cloud shield over much of Pima County, the coverage
of storms west of Tucson should be limited. The strongest storms
will be capable of producing rainfall amounts of 0.5-1" in less than
an hour, and localized flash flooding will be possible, especially
for places which received considerable rainfall over the last 24
hours.
Looking forward into this weekend, ample moisture will remain in
place with no large scale system to erode it. This will be
compounded by strong ridging over the western CONUS and therefore a
general easterly to northeasterly flow across the state. As a
result, daily chances of mainly afternoon and evening showers and
thunderstorms will occur into the upcoming weekend with PoPs above
climo for most locations.
Early next week, the GFS/ECMWF are hinting at a slight decrease in
shower and thunderstorm activity. Given the continued favorable flow
regime and lingering moisture, only very slight tweaks were made to
the inherited PoPs for Sunday through Tuesday, though values are
only slightly lower than those currently expected Friday and
Saturday. That said, daytime temps over the next week will remain in
the double digits and close to climo for early August due to cloud
cover and moisture levels.
&&
.AVIATION...Valid through 10/00Z. TSRA/SHRA will gradually expand in
coverage through the afternoon, with activity continuing during the
evening hours. SCT-BKN clouds 8k-15k ft AGL remain through the
period. SFC winds WLY/NWLY less than 12 kts this afternoon, becoming
variable as TSRA develop with gusty erratic outflow winds up to 40
kts. Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...The pattern remains favorable for scattered
thunderstorms areawide today, redeveloping each day into the start
of the weekend. Temperatures have also decreased near normal or a
few degrees below, continuing throughout the forecast. Terrain
driven 20-ft winds at less than 15 mph, except for in and around
thunderstorms where strong outflows may occur.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
Carpenter/Howlett
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson