Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/11/18
Area Forecast Discussion
National Weather Service La Crosse WI
624 PM CDT Fri Aug 10 2018
.SHORT TERM...(This evening through Saturday)
Issued at 314 PM CDT Fri Aug 10 2018
At 3 PM, scattered showers were moving south across north-central
Wisconsin and northeast Iowa. This was associated with a weak
convergence boundary between the upper level ridge to our west and
the trough located over the Great Lakes. Mixed-layer CAPES have
climbed up to 1500 J/kg. However, like much of this summer, there
is little shear. As a result, they develop and then quickly rain
themselves out as they shut of their supporting updraft. With the
loss of diurnal heating late this afternoon and early evening,
they will quickly dissipate.
For late tonight into Saturday, soundings show light winds up to
800 mb. However, they also show temperature-dew point spreads of
2F at 11.12z. As a result, put the greatest concentrations of fog
in the Mississippi tributaries and Wisconsin River Valley.
From late tonight into Saturday, the HRRR shows that smoke from
the western Canadian wildfires will spread into the area. The
highest concentrations will be along and west of the Mississippi
River. This smoke may briefly lower visibilities to as low as 5
miles at times. The Minnesota Pollution Control Agency has issued
an Air Quality Alert for the entire state through 12 PM Sunday.
On Saturday afternoon, another short wave trough will move
southeast through the Great Lakes. The CAM models indicate that a
convergent boundary will be located across central Wisconsin. Like
this afternoon, there will ML CAPES up to 1500 J/kg with weak
shear, so only expecting scattered diurnal showers and
thunderstorms.
.LONG TERM...(Saturday night through Friday)
Issued at 213 PM CDT Fri Aug 10 2018
500 hPa ridging continues across the region through Monday as a
Canadian trough cuts off across the lower Great Lakes into the Ohio
River Valley and a secondary cut-off low meanders across the Central
/Southern Plains. Skies look mostly sunny/clear both days with highs
generally in the 80s.
Tuesday into Wednesday, a northern stream short-wave moves across
the Dakotas into Minnesota and may ingest the secondary cut-off low
across the plains. These interactions complicate the overall flow
pattern and differ from model to model. End result in increasing
precipitation chances Tuesday into mid-week with POPs in the 20 to 40
percent range. Still early, but severe weather looks unlikely at
this time. Despite ample instability ahead of an eastward advancing
cold front, deep shear is lagging behind the boundary and generally
between 20 and 30 kts.
Synoptic flow becomes even muddier to end the week with the
potential for additional short-waves in a weak quasi-zonal pattern.
Consensus POPs from 20 to 30 percent seem reasonable, but overall
predictability is low.
Temperatures mid-week through Friday do appear to cool off a bit
behind Tuesday night`s frontal passage with daily highs generally in
the 70s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 624 PM CDT Fri Aug 10 2018
Diurnal cumulus continue to dissipate as the sun descends toward the
horizon. Skies to generally be cloud-free tonight, but there is the
smoke from the NW CONUS and SW Can wildfires that the NW to N
mid/upper level winds will be spreading across the area for later
tonight and Sat. Models indicate a thicker plume of smoke to be over
the area Sat and with diurnal mixing, some reductions in vsby are
likely, especially by later morning. This is always hard to fcst,
but several upstream vsbys in N MN in the 4-7SM range. Included 6SM
FU at both KRST/KLSE for much of Sat.
Another favorable night for radiational valley fog formation.
However, sfc dew points some 5F to 10F lower this afternoon vs. Thu
afternoon, and may limit the BR/FG a bit, especially in the broader
MS river valley. Only carried a 5SM BR FU at KLSE 09-14z at this
time.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...Boyne
LONG TERM....Boyne
AVIATION.....RRS
Area Forecast Discussion
National Weather Service Bismarck ND
936 PM CDT Fri Aug 10 2018
.UPDATE...
Issued at 936 PM CDT Fri Aug 10 2018
We added a mention of fog from 09 to 14 UTC over east central ND
and in particular the James River valley with this update. That
was predicated by seasonably high boundary layer moisture content
with surface dewpoints in the 60s to near 70 F in that region as
of mid evening, increased particulates for condensation resulting
from the low-level smoke concentration, and persistence given the
fog that occurred there last night and early this morning. Recent
HRRR cycles have also been simulating fog development there, and
locally dense fog is certainly possible. Otherwise, only minor
changes were made to the remainder of the forecast, though we did
reduce overnight lows ever-so-slightly in western ND where a drier
air mass and less smoke concentration closer to the 500 mb ridge
axis may promote a bit greater radiational cooling. The eastward
advancement of the ridge axis aloft could reduce smoke in parts
of southwestern and south central ND further on Saturday, as the
18 UTC HRRR-smoke simulation suggested, but we have maintained a
broad-brushed approach in carrying a smoke mention in all of our
forecast products for all of western and central ND through the
weekend at this juncture. Later trends in observational and model
data may allow us to refine spatiotemporal smoke trends slightly.
UPDATE Issued at 702 PM CDT Fri Aug 10 2018
Little change with this update cycle as we merely blended observed
trends and rapid-refresh guidance into hourly forecast fields for
the evening. As of 00 UTC, a weak surface boundary is noted from
northwest into central ND from about Stanley to Bismarck, with
higher boundary layer moisture content to its east where dewpoints
are generally over 50 F, but this feature will have very little
in the way of impact on sensible weather through the evening.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 327 PM CDT Fri Aug 10 2018
Currently, surface high pressure was over the Manitoba/North Dakota
border. The upper level ridge continues to build over the Rockies
and western Plains.
The upper level ridge will build further into the Northern Plains
this weekend. This anomalously strong thermal ridge is forecast to
have H850 temperatures in their climatological 99th percentile for
western and most of central ND Saturday. Record to near record
temperatures are forecast for Saturday. See the table in the long
term section for forecast and record temperatures.
In addition, the smoky haze from fires in the western US and Canada
will remain with us on Saturday.
.LONG TERM...(Saturday night through Friday)
Issued at 327 PM CDT Fri Aug 10 2018
Record to near record temperatures and a fire weather watch on
Sunday are the main highlights in the long term.
On Sunday the thermal ridge reaches its peak over western and
central North Dakota. The H700 temperatures are forecast to reach
their 99th to its maximum in western North Dakota. We are looking at
widespread max temperatures in the lower 100s across the western
half of North Dakota, with mid to upper 90s from the Turtle
Mountains to James Valley.
The latest model runs are more consistent on the cold front timing
and are projecting the front entering northwestern North Dakota late
Sunday afternoon, and reaching central North Dakota around daybreak
Monday morning.
Southerly winds are forecast to increase on Sunday to 20-25 mph. See
the fire weather section below for details regarding fire weather
impacts.
Regarding temperatures, record to near record temperatures are
forecast for both Saturday and Sunday:
Station Saturday`s high Sunday`s high
record forecast record forecast
Williston.....102 101 102 103
Dickinson.....102 100 102 102
Minot.........101 102 101 103
Bismarck......104 101 102 102
Jamestown.....103 93 102 95
The cold front moves southeast slowly across the state Monday, with
a chance of thunderstorms developing along the front mainly Monday
evening and night.
More zonal flow aloft develops thereafter, with periodic chances of
showers and thunderstorms. A relative cooler period with highs in
the 70s and 80s Tuesday through Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 936 PM CDT Fri Aug 10 2018
Smoke will continue across most of western and central ND through
the weekend, with occasional MVFR visibilities likely, especially
in northwest and central ND late tonight and Saturday morning.
Additionally, fog may develop over east central ND, including the
James River valley and the KJMS terminal, from about 09 to 14 UTC,
with potential IFR conditions. Winds will be light, and should
become predominately southerly on Saturday around 10 kt as weak
surface low pressure develops over Montana beneath the strong
ridge of high pressure aloft.
&&
.FIRE WEATHER...
Issued at 327 PM CDT Fri Aug 10 2018
Near critical fire weather conditions are possible Saturday.
Critical fire weather conditions are possible Sunday. A fire weather
watch has been issued for many western North Dakota
counties...including Williams and Mountrail counties and all
counties south and west of the Missouri River.
Very warm and dry weather continues into the upcoming weekend.
Widespread high temperatures in the low 100s are expected across
western and central North Dakota Saturday and Sunday. These
conditions will allow grassland fuels to continue to transition
towards curing.
Saturday:
High temperatures in the lower 100s are expected over western and
central North Dakota with minimum relative humidity values of 10
to 20 percent. Wind speeds are expected to be rather light
Saturday, generally 15 mph or less. Our confidence in stronger
winds, which would push conditions into the critical territory, is
not high enough at this point to issue any fire headlines, but
near critical fire weather conditions are expected Saturday,
especially southwest.
Sunday:
Forecast confidence continues to increase that winds on Sunday may
reach 20-25 mph with higher gusts during the peak heating of the
day, when relative humidity values are usually the lowest. A cold
front is forecast to enter far northwestern North Dakota late
afternoon Sunday, and push slowly through western and central North
Dakota Sunday evening into Monday morning. Mixing up to 8,000 feet
ahead of the front should allow southerly winds of 20 to 25 mph to
mix down to the surface on Sunday.
Speaking with the NDFS, grassland fuels over far western North
Dakota appear very dry, especially so south of McKenzie County. The
fuels farther north and east are not as far along in curing, but may
be able to carry fire very easily should 20-25 mph winds with low
relative humidity set up. FMO was not concerned with Renville, Ward
or McLean county.
Thus, even though weather conditions of less than 20 percent RH and
winds of 20-25 mph are expected across all of western and nearly all
of central ND (except James Valley)...will keep the fire weather
watch confined to west of the Missouri River and just north of it in
the northwest part of ND. A NWS employee account of dry grasses in
western Mountrail County and eastern Williams - thus wanted to
include areas in eastern Williams and western Mountrail counties in
the watch. As the front approaches, we do not expect the southerly
winds to reach criteria over Divide and western Williams counties,
but we may see eastern Williams reach criteria.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Sunday afternoon through Sunday evening
for NDZ009-010-017>020-031>034-040>045.
&&
$$
UPDATE...CJS
SHORT TERM...JV
LONG TERM...JV
AVIATION...CJS
FIRE WEATHER...JV
Area Forecast Discussion
National Weather Service Cleveland OH
1004 PM EDT Fri Aug 10 2018
.SYNOPSIS...
A stationary front from west to east across the area will move
little tonight. A weak wave of low pressure will move east along
the front and force the front south as a cold front Saturday. A
ridge of high pressure will build slowly east over the area during
the rest of the weekend and persist through Monday. Low pressure
will move north across western Pennsylvania by Monday night into
southern Ontario Canada Tuesday.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
A quiet evening is expected over northern OH and nw PA in the
wake of scattered to numerous showers and thunderstorms. Just
the far southwest part of the CWA near MNN to Knox County has
any lingering chance of showers/storms for the next hour or two.
The rain has moistened the boundary layer and fog has already
begun to form near CAK and BJJ. We can expect more fog to form
generally along and south of US-30 and a bit further north too.
Will mention patchy fog in the zones away from the lake. Current
overnight low temperature forecast seems reasonable with lows
ranging from near 60 in inland nw PA to near 70 on the islands
being surrounded by warm Lake Erie.
Drier air will filter south into the region on Saturday and help
stabilize the region. POPs have been lowered in the southern
counties.
The upper level trough is expected to deepen and become more
pronounced by Saturday morning resulting in the development of
an upper level low pressure system overhead. This trough and
subsequent low pressure system will trigger cyclogenesis over
the Carolina Coast. This low will begin a slow track north
toward the eastern portions of the forecast area by the end of
the weekend.
As the surface ridge tries to build in behind the front Saturday,
some drier air will push in as well and will bring an end to the
threat for showers and thunderstorms during the day Saturday into
Saturday night.
As upper level low pressure lingers over the forecast area and
surface ridge builds toward the local area, expecting temperatures
to be struggling to get into the lower 80s in the east but will make
it to the lower 80s west. Overnight lows will not change much and
stay in the 60s. Leaning in the direction of a blend of the HRRR
and GFS models with this forecast package as these two appear to be
doing well with handling the convection over the local area at this
time.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Upper level low will be over central Ohio on Sunday with chances of
showers/thunderstorms remaining in the forecast. The thunder will
spike late afternoon then taper off during the evening. These
conditions will likely linger into Tuesday as the low only slowly
drifts eastward. Best chances of rainfall will be from Mid Ohio to
NW PA.
Temperatures will be very close to seasonal averages through the
short term forecast.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
Upper level low pulls away to the east on Tuesday night. Dry
conditions with a brief period of ridging expected before moisture
returns to the area ahead of the next trough on Wednesday. Models
depict an upper low meandering out of the southern Plains that will
be pulled north across the area ahead of another trough moving
through the northern stream. It will take some time for the
atmosphere to moisten on Wednesday and and lowered pops for the
first half of the day. Thursday looks like the wettest day of the
week as these features merge overhead. Temperatures will be seasonal
with the warmest day expected on Wednesday with lesser
amounts of clouds and showers.
&&
.AVIATION /00Z Saturday THROUGH Wednesday/...
Showers and thunderstorms have moved south of the region and
weakened but have moistened the boundary layer. Cloudiness has
diminished. Dewpoints are rather high in the mid to upper 60s.
In rain cooled areas the temp/dewpoint spread is less than 5
degrees and winds are light. Conditions appear to be favorable
for fog development in areas away from Lake Erie especially
south of US-30 after 09Z which would affect YNG CAK and MFD and
perhaps FDY terminals. Visibility may drop below 2SM and Cigs
may form and lower below 1000 Ft. Fog should dissipate by mid to
late morning in the 1330-1500 UTC time frame. Less humid air
will gradually work south across the region Saturday afternoon
so VFR conditions are expected.
OUTLOOK...Non-VFR possible through Monday and possibly Wednesday.
&&
.MARINE...
Cold front will continue to drift southward toward southern Ohio
this evening. So expect to see northeasterly wind persist on the
lake into Saturday. Winds will weaken slightly Saturday night but a
surface trough will then persist over the central Great Lakes into
Tuesday. Current thinking is that the longer fetch may nudge winds
to 2 to 4 feet on Sunday for the central lake. This will need to be
watched closely with only slightly higher winds nudging waves up to
small craft advisory levels.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...Lombardy
NEAR TERM...LaPlante
SHORT TERM...Mullen
LONG TERM...KEC
AVIATION...LaPlante
MARINE...Mullen
Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
642 PM CDT Fri Aug 10 2018
.UPDATE...
Issued at 642 PM CDT Fri Aug 10 2018
Please see the 00Z Aviation discussion below.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 316 PM CDT Fri Aug 10 2018
An upper level trof will move past the Arrowhead this evening.
Moisture is a bit lacking, but what is available will lead to a few
thunderstorms. Thermodynamic profiles suggest a general thunder
scenario. Rainfall amounts will be on the light side however.
Otherwise, Upper level and surface ridging will build across the area
tonight and Saturday. Smoke will continue to drift over the region
thanks to a northerly flow aloft bringing the smoke from Canadian
fires into the region. An air quality alert is in effect until noon
Sunday. Warm minimum and maximum temps tonight and Saturday.
.LONG TERM...(Saturday night through Friday)
Issued at 316 PM CDT Fri Aug 10 2018
The upper ridging persists through Monday. At the surface, a
southwesterly flow develops Sunday afternoon through Monday evening.
This will continue to bring a warm and humid airmass into the
region. Monday night finds a cold front beginning to affect the
international border area. This front will be aided by a piece of
vorticity moving along this area in a westerly flow. Expect showers
and a few thunderstorms to develop along the border and drift
southeastward.
The cold front slowly progresses into the forecast area through
Tuesday night before stalling out. Meanwhile, an upper level wave
will be dropping south out of south central Canada to the northern
Minnesota border by 12Z/7am Wednesday. Additional showers and storms
will percolate across the region, diminishing Wednesday night from
northwest to southeast. The ridging returns on Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 642 PM CDT Fri Aug 10 2018
High pressure will remain in place over the Upper Mississippi
River Valley through the forecast period. Flow aloft will be
northwesterly, which will advect smoke from Canadian Wildfires
into the region. This will bring some visibility reduction with
MVFR conditions anticipated at INL. HIB/BRD will also see some
visibility reduction, but should remain in the VFR range this
evening.
As was the case yesterday expect radiation fog to develop as the
airmass is essentially the same as it has been the past two
nights. Uncertain how the smoke will impact the fog development,
but mostly utilized persistence in forecasting fog formation and
when the lowest visibilities are expected. As of right now
anticipate MVFR to IFR visibilities, but lower are possible. Just
have held off at this point from lower due to the smoke over the
region. Fog will dissipate around 12Z to 14Z as the mixed layer
develops. Expect smoke to impact terminals on Saturday per HRRR
smoke guidance with some visibility reduction. Winds will be less
than 10 knots through the forecast.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 62 88 62 86 / 0 0 0 0
INL 57 90 63 91 / 0 0 0 0
BRD 63 88 64 87 / 0 0 0 0
HYR 61 87 59 87 / 0 0 0 0
ASX 62 85 59 86 / 0 0 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
UPDATE...WL
SHORT TERM...GSF
LONG TERM...GSF
AVIATION...WL
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1006 PM CDT Fri Aug 10 2018
.UPDATE...
A broken line of storms has developed oriented northeast to
southwest from Kendall County down to Dimmit County. This line is
very slowly moving to the east. These storms are producing copious
amounts of lightning, moderate to heavy rain, and gusty winds. A gust
front has begun to move out ahead of the leading edge of the
convective line, which may begin to decay the intensity of the
convection and hinder its eastward progress if it manages to cut the
storms off from their warm, moist inflow source. In the short term,
grids have been updated for current trends. PoPs out west have been
decreased considerably where rain has ended, with PoPs increased
considerably where storms are ongoing and heading in the near term.
Convective allowing models have been performing quite poorly today,
with the most recent HRRR runs initializing terribly. Thus, I am not
putting too much stock in what they are showing for the remainder of
the evening and overnight hours. For now, essentially using a blend
of various models for PoPs in the 1 am to 7 am (6z to 12z) time
frame, with this resulting in decreasing PoPs a bit, especially
across the western areas and into the Hill Country (from 70% down to
50%).
&&
.PREV DISCUSSION... /ISSUED 704 PM CDT Fri Aug 10 2018/
AVIATION...
Scattered to numerous showers and storms continue around DRT and
points to the northeast. Outflow boundary continues to move closer to
the San Antonio sites and latest runs of the HRRR does show some
isolated activity for the I35 sites later this evening. Will include
the mention of VCTS for the San Antonio sites and VCSH for AUS for
later this evening. Beyond the near-term, it is tough to pin down
exact precip timing, but think the best chances will be in the
afternoon hours for all sites tomorrow and will include vicinity
activity. There is a small chance for some MVFR ceilings after
daybreak tomorrow, but opted not to include the mention of that for
now. Changes to the TAFs regarding precip is likely as timing
differences become known.
PREV DISCUSSION... /ISSUED 250 PM CDT Fri Aug 10 2018/
SHORT TERM (Tonight through Saturday Night)...
Through the remainder of the afternoon and into the evening focus for
showers and thunderstorms will be across the southern Edwards Plateau
and into the western Hill Country, where forcing along differential
heating/remnant outflow boundary is best. Several CAMs models
suggest upstream convection developing southward into portions of
Val Verde, Edwards, Real, and Kerr counties. Convection could
build further south toward the U.S. 90 corridor through the mid
evening into the instability axis, where SPC analysis indicated
MLCAPE approaching 3000 J/kg. A few strong storms are possible with
inverted V soundings out west indicating potential for gusty winds.
However main threats will be lightning and some brief heavy
downpours. Forecast confidence overnight is low, however there are
some signals in a few of the CAMs of development of isolated to
scattered convection farther east into the CWA.
The mid and upper level trough axis will deepen Saturday and Saturday
night, with the base of the trough orienting itself across the
northwest CWA. Convection during the day on Saturday is hard to
pinpoint, and may be mainly diurnally driven in the afternoon closer
to outflow boundaries left over from overnight convection.
However focus Saturday night in most of the models appears to be
through the southern Edwards Plateau, western Hill Country and Rio
Grande as a weak inverted low level trough develops over the region,
low level jet increases, and larger scale ascent/forcing in the base
of the trough align. There is the potential for locally heavier
pockets of rainfall through this region, given climatological high
precipitable water values and relatively slow storm motions and
potential for mergers. Some streamer convection will also be
possible farther east into and east the I-35 corridor.
LONG TERM (Sunday through Friday)...
The base of mid and upper level trough axis will remain across the
far northwest CWA Sunday and Sunday night. As ridge across the
northern Gulf of Mexico nudges slightly to the west the deep
moisture feed focuses mainly near I-35 west to the Rio Grande.
Difficult to pinpoint evolution of storms during the day on Sunday
and may be very dependent on what happens Saturday night. However,
models are consistent with showing potential for another nocturnal
event Sunday night across the Hill Country and Rio Grande given the
deep moisture over the area, larger scale ascent with the trough,
and stronger low level jet orientation more perpendicular to the
escarpment.
While generally the southern Edwards Plateau, Hill Country, and Rio
Grande could use the rainfall given the drought conditions, there is
the possibility of some pockets of rainfall rates that develop that
could produce localized flooding. We will highlight this in the HWO.
Drier air will gradually build into the region from east to west
Monday through Monday night as the mid and upper level ridge flattens
over the area and trough lifts to the north. This will result in
drier and warmer conditions developing Tuesday through the remainder
of the forecast.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 75 92 75 91 76 / 50 50 60 40 50
Austin Bergstrom Intl Airport 75 92 74 92 76 / 50 50 60 40 40
New Braunfels Muni Airport 74 92 75 92 75 / 50 50 50 40 50
Burnet Muni Airport 73 89 72 88 72 / 60 50 60 50 70
Del Rio Intl Airport 77 90 73 85 73 / 50 50 80 70 70
Georgetown Muni Airport 74 91 73 90 75 / 50 60 60 40 50
Hondo Muni Airport 74 94 74 91 74 / 70 40 60 60 70
San Marcos Muni Airport 76 92 74 92 76 / 50 50 50 40 50
La Grange - Fayette Regional 77 93 75 94 77 / 30 50 40 30 20
San Antonio Intl Airport 76 93 76 91 77 / 60 50 60 50 60
Stinson Muni Airport 77 93 76 93 77 / 50 40 60 50 60
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...Hampshire
Synoptic/Grids...BMW
Area Forecast Discussion
National Weather Service Hastings NE
557 PM CDT Fri Aug 10 2018
.SHORT TERM...(This evening through Sunday)
Issued at 218 PM CDT Fri Aug 10 2018
The most notable feature currently is the smoke that has moved in
from the fires over over Washington state and British Columbia.
This has lead to hazy skies, but has remained mostly aloft, so we
have kept any mention of smoke out of the grids. The HRRR and RAP
smoke models indicate that we should see this smoke slowly become
thinner through tonight and tomorrow.
Other than that, the short term forecast is pretty quiet. The
forecast area will remain under the influence of an upper level
ridge through Sunday, which should lead to dry conditions. Winds
will become southerly Saturday and Sunday but will remain relatively
light as the weak surface high pressure area moves to the east.
Temperatures will be similar to today, with highs in the upper 80s
to low 90s.
.LONG TERM...(Sunday night through Friday)
Issued at 218 PM CDT Fri Aug 10 2018
The quiet pattern will begin to change on Sunday as models develop
an upper low over western Texas and slowly moves it through the
TX/OK panhandles and into southwest Kansas. There is some question
on how quickly deep moisture will return to the area with this
feature, but the model consensus would bring at least some chance
into souther parts of the area late Sunday night, with a better
chance for the entire area Monday and Tuesday.
This feature will be very slow to move through the area, and it will
take a northern stream wave to finally kick it out of the area
Tuesday night into Wednesday. As a result, I am cautiously
optimistic that the southeastern portions of the forecast area (that
are also some of the driest spots) will see beneficial rain.
Although its still early, the overall threat for severe weather
looks somewhat limited due to a lack of low-level shear.
Nevertheless, its still August so we can`t completely write off
the threat at this point.
Increased cloud cover will keep temperatures a bit cooler through
the beginning of the week, with highs only forecasted to reach the
low to mid 80s each day.
Periodic chances for thunderstorms continue Wednesday through
Thursday night as remain in a messy zonal to slightly
northwesterly upper level flow pattern.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday)
Issued at 547 PM CDT Fri Aug 10 2018
Smoke/haze has reduced the visibility at KGRI to 5SM for the
majority of the day. Have maintained a slightly reduced visibility
into tonight, before increasing. Cloud cover will be fairly
minimal with a scattered mid/high deck possible heading into
Saturday.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
SHORT TERM...Mangels
LONG TERM...Mangels
AVIATION...Fay
Area Forecast Discussion
National Weather Service Wilmington NC
940 PM EDT Fri Aug 10 2018
.SYNOPSIS...
Bermuda high pressure anchored offshore and an area
of low pressure inland, will bring an increase in showers and
thunderstorms through the latter half of the weekend into
early next week. Rain chances begin to decrease by the middle of
next week, as low pressure moves north of the region.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 9 PM Friday...Upper level impulse over western NC generating
convection well to the west of the FA attm. This feature will get
close enough to the area overnight that it could kick off a shower
or storm but it will be fighting stability induced by nocturnal
cooling. Have lowered pops to slight chance all areas overnight with
no pop eastern areas until about 2 AM. Forecast mins in the
middle 70s look good. Previous discussion from 3 PM follows:
Cu building along northern border and just north of local area this
afternoon in best moisture and lift just south of sfc front.
Modified sounding showed ML CAPE up around 2k and PW increasing to
over 2 inches with DCAPE up around 735 by late this aftn. Dry air
and subsidence in the mid levels has provided a bit of cap to our
south as ridge extends up through the Southeast. Sea breeze made a
good run inland as prevailing flow remained weak with an isolated
shower or two, but the main activity will remain just south of front
over northern tier of forecast area. HRRR did a decent job of
depicting the convection this aftn so far, weakening into this
evening as heating of the day cuts off.
Expect a quiet overnight for the most part as ridge gets nudged
farther south and east as deepening mid to upper trough makes
its way east toward the Carolinas. A few minor perturbations
will ride through the deepening W to SW flow over the Central
Carolinas and should see some convection flare as front moves
back north and west of the area as a warm front. This activity
should remain to the north of local forecast area for the most
part. Will keep minimal pops over Pender and Bladen counties
late tonight, but should see a lull through the morning before
convection begins to flare along sea breeze and then I-95
corridor Sat aftn as upper level dynamics enhance activity along
trough inland. Heating of the day and moistening of the
boundary layer on Saturday will add to the upper level dynamics,
increasing the potential for shwrs/tstms Sat aftn into the
evening.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 300 PM Friday...An upper level trough begins to cut-off
over the Great Lakes around 00 UTC Sunday and drops over the
Ohio River Valley by Sunday night.
At the surface a cold front will shift across the Carolinas and
stall just to the west of i-95. This will align the best
moisture and instabilities over the eastern 2/3 of the forecast
area. The highest precipitable waters of 2.0" will be along the
coast and BL CAPE values will run from 1500 J/kg in the extreme
west of our area to 2500 J/kg at the coast. So can expect good
chances of thunderstorms Sunday with heavy rains possible.
Lows will be in the lower to middle 70s west of Interstate 95
and middle 70s elsewhere except a few upper 70s along the
immediate beaches. Highs will be in the upper 80s to around 90
with the increased cloud and storm coverage.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 300 PM Friday...`Cooler and Wetter, Followed by Drier and
Hotter` may be one way to describe anticipated long range
weather. ECMWF/GFS solutions showing good H5 adhesion in
dropping an upper low SE across West Virginia Monday, then
northward into New England Wednesday. Sensible weather impacts
include, below normal Max-T numbers Mon/Tue due to high rain
chances, and above normal overnight lows due to cloudiness. The
`snap-back` upper ridge in wake of the departing upper system
will bring hotter and drier air Thu/Fri, and notably lower
daytime POP values.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 00Z...Expect mainly VFR conditions through most of the valid
TAF period, now that convection over the area has mostly died. There
is an outside chance for patchy MVFR fog tonight but the probability
of it occurring does not warrant inclusion in the terminals attm.
Convection well to the west should not affect the area overnight.
Aft 18Z, have included VCTS northern and western terminals to
account for expected isolated to scattered convection.
Extended Outlook...MVFR/IFR from isolated to scattered SHRA
and TSRA, especially each afternoon and evening across all
sites through Saturday. Increasing chances for showers and
tstms on Sunday. Isolated convection Monday through Wednesday.
&&
.MARINE...
NEAR TERM /THROUGH SATURDAY/...
As of 900 PM Friday...Winds have dropped back to about 10 KT over
the waters and should remain there overnight. Winds will increase
heading through Saturday as gradient tightens between a trough
inland and Atlantic high pressure offshore. Seas will run 2 ft or
less tonight and will increase to 3 to 4 ft by late Saturday.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 300 PM Friday...A cold front will be moving toward the
coast on Saturday evening but will stall around 100 miles
inland. This in turn will see the southwest winds blowing around
15 knots through the entire period.
With the duration and fetch of the wind, the seas will increase
from 2 to 3 feet Saturday night to 3 to 4 feet on Sunday and a
few 5 footer are expected at 20 miles off the coast mainly
north of Little River Inlet after midnight Sunday.
LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 300 PM Friday...Anchoring of Bermuda High pressure this
period maintains a SW wind, generally between 10-20 kt, a few
higher gusts inshore during the afternoon heating inland. Just
about all of the wave energy will be tied to wind-seas, and
short-period waves, with very little long period wave energy
seen. TSTMS and showers to be numerous MON/TUE, with a drying
trend beginning WED.
&&
.TIDES/COASTAL FLOODING...
As of 800 PM Friday...The latest forecast has the tide gage located
on the lower Cape Fear River at downtown Wilmington peaking around 6
ft MLLW about 947 pm EDT, which is this evening`s high tide. Shallow
flooding commences at the 5.5 ft MLLW height threshold and occurs
within a window surrounding high tide. For tonight`s potential,
flooding will be possible between 8 pm EDT to midnight EDT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...Beach Hazards Statement from 6 AM EDT Saturday through
Saturday evening for SCZ054-056.
NC...Beach Hazards Statement from 6 AM EDT Saturday through
Saturday evening for NCZ106-108-110.
Coastal Flood Advisory until midnight EDT tonight for NCZ107.
&&
$$
SYNOPSIS...
NEAR TERM...31
SHORT TERM...RH
LONG TERM...MJC
AVIATION...31
Area Forecast Discussion
National Weather Service Phoenix AZ
855 PM MST Fri Aug 10 2018
.UPDATE...
Updated DISCUSSION and AVIATION sections.
&&
.SYNOPSIS...
Favorable northeasterly flow aloft along with sufficient
moisture will keep an active monsoon pattern in place through
the weekend. Thunderstorms that develop will have the potential to
approach severe limits, with strong winds, frequent lightning,
areas of blowing dust, and locally heavy rain possible. The
increase in moisture will also help keep temperatures below normal
through the weekend.
&&
.DISCUSSION...
So far, this evening has been much quieter than last evening -
despite strong northeasterly steering flow. Activity over the
higher terrain (especially Rim and southern Yavapai County) has
been more isolated. The 00Z PSR sounding shows a cap at about 760
mb with considerable associated CIN. The MLCAPE values not overly
impressive either at around 450 J/kg. However, Gila County has
just recently become quite a bit more active - likely in
associated with a disturbance aloft. With strong storms moving
toward the lower terrain of south-central AZ (including metro
Phoenix) and good temp/dew point spreads, there is good potential
for very strong winds to affect a large area. The key question is
whether or not the outflow will be strong enough to overcome the
CIN. In recent days, we`ve seen high CIN values be overcome so
have not given up on storms moving across the valley floors.
As for model data, the HRRR has been trending down on it`s
activity the 02Z has now dropped the late night activity for Gila
and Maricopa Counties. However, it has been handling current
activity poorly. For instance, it hasn`t been depicting the
northern Yavapai storms nor the Gila County storms (as of this
writing). Meanwhile, the NAM Nest which has handled early evening
activity better, brings strong storms right through Gila,
Maricopa, and Pinal Counties. With fast storm movement, we may
not see much in the way of true flash flooding - but could still
see nuisance flooding. Will not cancel the Flash Flood Watch
yet, but may need to pare back some areas.
&&
.PREVIOUS DISCUSSION...Issued 213 pm....
Latest water vapor imagery depicts an elongated trough in TX
extending back westward into Arizona. Further north, an
anticyclone predominates across the Great Basin. Between these two
systems, a much stronger than normal northeasterly steering flow
persists across the Desert Southwest.
Still expecting tonight to be relatively active across the forecast
area, with the aforementioned northeasterly flow and well-below
normal temperatures in the mid-levels. Latest ACARS soundings
out of KPHX still show that temperatures have barely warmed from
this morning and are as cold as -8C to -9C at 500 mb. Looking
upstream, latest water vapor imagery shows some reflection of
increased drying associated with vorticity near the Four Corners.
This will likely provide extra ascent to cells forming along the
Mogollon Rim later this afternoon and this evening.
Forecast is weighted heavily towards the HREF, which indicates that
activity will be most concentrated across south-central Arizona. NAM
Nest initialized last night`s activity well and also suggests
activity will move through the Phoenix area tonight. Successive runs
of the HRRR also continue to point to a complex of storms dropping
rapidly out of the higher terrain and into the Phoenix area perhaps
as late as midnight. Given its past success this summer, this seems
reasonable and above average PoPs were retained for tonight.
PWATS are not exceptional, though still sufficient to produce storms
with heavy rain. The most vulnerable areas for flash flooding are
across eastern Maricopa County, where the highest rain totals have
been observed the past few days. However, there is a discernible
threat further south and west, given the stronger than normal
steering flow and a Flash Flood Watch has been issued as far west as
La Paz County.
&&
.AVIATION...
South-Central Arizona including KPHX, KIWA, and KSDL...
Storms over Gila County will push outflow into metro Phoenix. The
TAF site most likely to see a strong wind shift (and reduced
visibilities from this outflow) is KIWA. Expect at least isolated
storms to move across the Valley floor behind the outflows
(generally from east to west). Have held off for now on TSRA in
the TAFs but that could very well change. Any storms that form
will be able to reinforce the pre-existing outflow winds in terms
of strength/speed but will make for more erratic directions. They
would also produce brief very heavy rain.
Southeast California/Southwest Arizona including KIPL and KBLH:
Storm activity near and west of the Lower Colorado River Valley
looks unlikely. However, storms from south-central Arizona may
reach portions of La Paz and Yuma County (after midnight). More
likely will be outflow from distant storms. At this time, the TAFs
do not reflect outflow related wind shifts but that is subject to
change.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Monday through Friday: Monsoon moisture and precipitation
chances are forecast to decrease early next week. During
this period, storms will mainly be relegated to the higher
terrain with only a remote chance in the lower elevations.
Consequently, temperatures will be near to slightly above average
while afternoon humidity minimums drop between 15-20 percent for
the lower elevations. Apart from this, winds will be light with
the typical afternoon breezes. A better chance of storms may return
late next week.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter reports may be needed later this week.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Flash Flood Watch until 2 AM MST Saturday for AZZ531-533-534-
536>544-546-548>551.
Flash Flood Watch until 11 PM MST this evening for AZZ545-547-
552-556>558-560>563.
CA...None.
&&
$$
DISCUSSION...AJ
PREVIOUS DISCUSSION...Hirsch/Hernandez
AVIATION...AJ
FIRE WEATHER...Hirsch/Wilson