Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/31/19
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
817 PM EDT Tue Jul 30 2019
.AVIATION...
The combination of geopotential height increase, positive time
tendency for anticyclonic surface flow trajectories and diabatic
release of lake convergence boundaries this evening will force a
backdoor cold front through all of Southeast Michigan by 09Z
tonight. Radar trends suggest that that shower potential has ended
for all of the area except Lenawee and Monroe Counties. First order
of business for TAFs is that surface wind directions will shift out
of the northwest for the start of the taf period then veer to the
north or northeast this evening while remaining light. Forecast
soundings show a lack of dry air advection in the 3.0 to 7.0 kft agl
layer throughout tonight. Residual moisture in this layer will
result in potential for VFR cloud deck the latter half of the night.
VFR cloud base cumulus is expected to develop for Wednesday
afternoon. Light north to northeast winds will hold for Wednesday.
For DTW...Rain potential has pushed to the south and east of the
airspace this evening. Light northwest winds to start the TAF will
veer to the northeast this evening. Low forecast signal because of
weak wind. Little dry air advection tonight will bring persistence
in midcloud cigs tonight. High based diurnal cumulus will then
develop by noon Wednesday.
.DTW THRESHOLD PROBABILITIES...
* Medium for ceilings aob 5kft after 08Z tonight.
&&
.PREV DISCUSSION...
Issued at 355 PM EDT Tue Jul 30 2019
DISCUSSION...
Isolated to scattered showers will persist into the evening hours as
a cold front continues to advance from central MI through southeast
MI. Overall coverage has been low but a differential heating boundary
turning into an outflow boundary was responsible for most of the
activity thus far. As this boundary interact with the lake breezes
off Lake Huron, St Clair and Erie around the Detroit Metro area
additional showers may develop considering there is a pocket of
SBCAPE between 1000-1500 J/kg. A stray thunderstorm cannot be ruled
out at boundary triple points but there has been zero lightning
strikes as of yet.
The surface cold front will then pass through this evening ushering
a drier airmass into the area and ending all chances of showers.
Dewpoints across northern lower MI are in the 50s with 40s across
the U.P. High pressure to the west will then slide into the are
tonight becoming centered over MI for the next few days. As it
slides east tonight, RAP and NAM both suggest the northeast flow off
Lake Huron will bring a surge of moisture under the inversion
resulting in stratus moving inland across SE MI. This will hold a
few hours into Wednesday morning before dry air and subsidence erode
this moisture. Ridging aloft and at the surface will then lead to
pleasant weather through the end of the week with temps holding
around 80, low humidities and plenty of sun.
The extended forecast this weekend will feature the continuation of
broad high pressure over the Midwest. This will keep winds light and
precipitation limited. With H8 temps around 13 C, temps should be
right near normal by Friday afternoon with high based diurnal cu
overhead as PWATs recovery slightly back toward the 1 inch mark. Low
to mid-level flow will be very weak during this time with an H5
trough digging into nothing but subsaturated air. Saturday will
start off dry in the morning, however, GFS/CMC/ECMWF are all
advertising a period of precip Saturday afternoon for portions of
Saginaw Bay and the Thumb. PWATs will push the 75th percentile at
over 1.30 inches as shortwave energy rounds the base of a H5 trough
axis. It should be noted that the ECMWF is more muted in the
periodicity and amplitude of the shortwave ripples suggesting even
lower shower/storm potential. Temps will be on the rise over the
Metro area, likely running a couple degrees above average.
Sunday will be relatively quiet with no boundaries or airmass
changes in play just yet. Guarded high pressure over the Midwest
will still be lingering with surface winds becoming a bit more
northerly composed helping to keep max temps in check. Some dry air
advection will be ongoing well before a trough dives southeast from
Wisconsin. Current thinking for the workweek is that any convection
that fires off Monday afternoon will be shortwave induced within the
warm sector of the advancing surface reflection. By Tuesday
afternoon, the front should move through bringing more widespread
shower activity from the cold front progression. Temps will be
near or slightly above climatological norms for early next week.
MARINE...
A cold front will continue pushing southeast through the Great Lakes
this afternoon and evening. In its wake, northwest wind tonight
gusting upwards of 20 kt across northern Lake Huron, then northeast
wind gusting up to 15 kt tomorrow morning across Lake St. Clair and
western Lake Erie. High pressure then expands in from the west
through the mid and late week, resulting in an extended period of
favorable boating conditions with light winds and low wave activity.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....CB
DISCUSSION...DRK/KK
MARINE.......TF
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Fort Worth TX
645 PM CDT Tue Jul 30 2019
.AVIATION...
Isolated showers and storms will continue through sunset,
remaining well south of the Metroplex Airports. However, some of
this activity will continue in the vicinity of Waco.
Otherwise, expect VFR through Wednesday afternoon with few to
scattered daytime Cu and scattered high clouds.
The light north winds currently at the Metroplex airports will
veer to the southeast this evening and remain south/southeast at
speeds less than 12 knots through Wednesday afternoon. Generally
southerly winds less than 12 knots will continue in Waco, except
for some brief variability near any thunderstorm.
79
&&
.SHORT TERM... /Issued 352 PM CDT Tue Jul 30 2019/
/Through Tonight/
While most areas across north and central TX will remain rain
free through this afternoon and evening and into tonight, some
isolated showers and thunderstorms are possible mainly south of
I-20.
Seasonably hot and humid conditions are observed across north and
central TX this afternoon. Temperatures are in the upper 90s and
some areas have reached 100 degrees including DFW, which eclipsed
the century mark for the first time this year. Surface winds are
now solidly out of the north across north TX with areas in central
TX beginning to make the transition from southerly to northerly
winds as a surface boundary slides southward. This boundary has
provided enough lift to result in isolated showers and
thunderstorms this afternoon south of I-20.
This isolated shower and thunderstorm activity is expected to
continue for areas south of I-20 through the afternoon and into
the evening with activity quickly diminishing after sunset.
Instability is very limited so severe storms are generally not
expected but given how toasty the temperatures are there is the
potential for an isolated storm to produce gusty downburst winds.
Hoeth
&&
.LONG TERM... /Issued 352 PM CDT Tue Jul 30 2019/
/Wednesday through Monday/
Mostly tranquil and rain-free weather is expected through a
majority of the long term forecast period. The exception will be
early Wednesday morning and again on Saturday and Sunday where low
rain/storm chances are advertised.
A mild morning is on tap for a majority of North and Central Texas
with most locales only falling into the 70s for overnight lows. A
few of the sheltered spots may bottom out in the upper 60s. RAP
isentropic progs indicate some gradual ascent atop the surface
layer along the 305-310K theta surface in the wake of this
afternoon`s wind shift and there could be just enough low level
saturation to produce some drizzle or very light rain across
Central Texas. I`ll advertise a 15 PoP with a mention of light
rain across the Brazos Valley, but widespread measurable rainfall
appears most unlikely. A repeat of patchy dense fog is not
expected as the surface trough responsible for the reservoir of
low level moisture will be quite diffuse.
After the risk for Wednesday morning rain showers across Central
and East Texas...summer heat will continue with upper 90s to
triple digit heat likely overspreading most of North and Central
Texas for afternoon highs. The mid-level ridge that migrates
eastward over the southern Plains should ensure that the risk for
any rain/storms remains near zero. Afternoon dewpoints should
remain in the upper 60s to low 70s through the end of the
week. While it won`t feel pleasant during peak heating...it
appears that we will remain just shy of our heat advisory
criteria. Regardless, it will still feel quite hot outside and
heat safety protocols should continue to be exercised.
The weekend will bring about a slight change to the upper air
pattern. The mid-level ridge will slowly creep back towards the
west and this will result in slight northerly flow aloft. Not too
dissimilar from this past Monday...there will be the potential
for some showers and isolated storms to drift southward out of
Oklahoma into North Texas. Instability forecasts do not indicate
an overly impressive profile...but with the height gradient
tightening between the ridge to the west and the upper trough to
the east...this could increase deep layer shear values up to
around 30 knots. This may foster some loosely organized multicell
line clusters capable of some gusty winds. The best time frame for
any showers and storms will be late Friday afternoon and again on
Saturday and Sunday. The risk for rain/storms and increased cloud
cover may hamper diabatic heating...especially east of I-35...and
temperatures are forecast to be below normal. If the latest GFS
is to verify...very cool conditions...highs only in the 80s...will
be possible. At this time, I feel that the GFS is a little too
aggressive with its development of a surface low down across the
Concho Valley---thus inducing stronger CAA. For now, will
undercut blended guidance given that we could see at least one day
of slightly more northerly flow.
Beyond the weekend, there is a signal that the surface flow will
remain more easterly. This should equate to below normal
temperatures at least through Tuesday with a slight warming trend
thereafter. Again, if the GFS is to be believed, conditions could
be quite a bit cooler as more northeasterly winds would likely
instigate a larger magnitude of cool/dry air advection.
Bain
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 79 99 78 98 78 / 0 0 0 0 0
Waco 75 98 76 98 76 / 10 5 0 0 0
Paris 74 93 73 92 73 / 0 0 0 5 0
Denton 75 98 77 97 76 / 0 0 0 0 0
McKinney 75 96 75 96 76 / 0 0 0 0 0
Dallas 80 99 79 98 79 / 5 0 0 0 0
Terrell 76 97 75 96 76 / 5 0 0 0 0
Corsicana 75 95 75 95 75 / 20 5 0 0 0
Temple 74 98 75 97 74 / 10 5 0 0 0
Mineral Wells 74 99 74 98 74 / 0 0 0 0 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
79/11
Area Forecast Discussion
National Weather Service Hastings NE
624 PM CDT Tue Jul 30 2019
.SHORT TERM...(This evening through Wednesday)
Issued at 317 PM CDT Tue Jul 30 2019
An upper ridge of high pressure dominated the weather pattern
across the interior CONUS today, with a shortwave trough
translating around the ridge providing lift for showers and
isolated thunderstorms across northeast Neb today...on the edge of
northeast counties. With the convection nearby have included the
possibility of a sprinkle the remainder of the afternoon.
Convection tonight is not looking overly promising, however
chances are not zero either. High plains convection could hold
together with high resolution model indicating dissipating
showers/storms may reach our southwest zones late this evening.
Overnight, on the nose of the low level jet additional development
is expected to focus across eastern Neb, with our eastern zones on
the edge of the activity. So while, chances are not great, low
pops are in the forecast.
On Wednesday, a warm front will lift north through KS bringing
continued hot conditions to our southern zones with highs topping
out in the mid/upper 90s south of the boundary. The hot temps
combined with dps will lead to several hours of aftn heat indices
of 100 to 105 degrees for locations southwest of a Cambridge, NE
to Beloit, KS line. These temps are near but generally just below
heat advisory headlines and the forecast heat continues to be
mentioned in the HWO.
Also Wednesday, models differ on whether the cap will hold or not
along the front, but with the NAM and HRRR suggesting potential
for an isolated storm, have included some low pops mainly in north
central KS in the late aftn/evening.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 317 PM CDT Tue Jul 30 2019
Wednesday night...in a similar setup to tonight, a strengthening
low jet combined with an upper jet streak/shortwave trough is
expected to focus showers/storms across eastern Neb/KS (with our
eastern zones on the edge of the convection). The upper ridge axis
begins to break down overnight and the surface boundary is
expected to stall near the Neb/KS stateline. Models suggest cooler
air and low clouds will settle in north of the front Wednesday
night with the potential for fog development overnight into
Thursday morning.
Temps have begun to trend down for Thursday with models suggesting
the potential for cloudy, cooler and possibly damp conditions
north of the front. 12Z MOS guidance is running roughly 10 degrees
cooler than our current forecast highs for Thursday.
Thursday night/Friday will see our better chances for
precipitation before the forecast dries out over the weekend as
the upper ridge axis rebuilds. Precip chances remain minimal early
next week, with slight chances returning towards Tuesday as
systems deamplify the ridge axis.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 619 PM CDT Tue Jul 30 2019
Overall, a fairly quiet forecast for this TAF period. Still an
outside chance of some isolated precip in the area of the terminal
sites later tonight, so did keep a VC mention going, but
confidence is not high. Models continue to show the potential for
marginal LLWS shear after midnight through the early morning
hours. Some uncertainty remains with clouds as we get toward
sunrise...some models showing the chance for sub-VFR clouds
developing, but not all agree. Have a SCT030 mention going at
this point. Winds will remain generally southeasterly through the
period, gusts diminish this evening, but speeds look to remain
around 10-15 MPH overnight. Guidance suggest speeds taper off more
toward the end of this period.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
SHORT TERM...Fay
LONG TERM...Fay
AVIATION...ADP
Area Forecast Discussion
National Weather Service Goodland KS
935 PM MDT Tue Jul 30 2019
.UPDATE...
Issued at 430 PM MDT Tue Jul 30 2019
A subtle convergence boundary per 88D radar extends from near
Trenton Nebraska to Colby and Tribune. SPC mesoscale analysis
shows DCAPE values of 1500 to 1800 J/KG in this axis. Latest few
runs of the operational and lesser extent experimental HRRR models
suggests isolated thunderstorm development near the convergence
boundary through about 01z or so. HRRR wind gust forecasts suggest
wind gusts up to around 70 mph or so with any storm that develops.
Soil moisture imagery shows very dry conditions near where HRRR
suggesting thunderstorm initiation develops. If storms develop and
generate the wind like the models suggest blowing dust and reduced
visibilities could be a concern.
I`ve updated the HWO to mention the threat albeit somewhat low.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 121 PM MDT Tue Jul 30 2019
The main concern with the forecast over the next few days will be above
normal temperatures in the region. An upper ridge remains over
the western CONUS with northwest flow aloft over the Tri-State
region. High temperatures will range from the mid-90s to low 100s
this afternoon and lows will range from the mid-60s to low 70s.
A boundary remains situated over the Kansas-Colorado border this afternoon.
EBWD values range from 25-35kts this afternoon in the region.
700-500mb lapse rates range from 8.0-8.5 C/km with decent DCAPE
(1400-1800 J/kg) and MLCAPE (500-1500 J/kg). Weak convergence
along the boundary may be enough to get a few showers or
thunderstorms to fire off in northeastern Colorado and far
northeastern Kansas. Any storms that do develop may produce some
localized heavy rain, gusty winds, and some small hail.
Wednesday high temperatures will once again rise into the mid-90s
to low 100s. Normal high temperatures range from the upper 80s to
low 90s with normal lows ranging from the low to mid-60s.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 130 PM MDT Tue Jul 30 2019
A change in the upper level pattern for the beginning portion of the
extended will bring a bit of relief to the area from the trend of
above normal temperatures. Wednesday night into Thursday...the upper
level region currently centered over the central Plains...will
retrograde slightly into the Rockies and amplify from late Thursday
on into next week.
The expected amplification of the ridge will allow for the current
westerly flow to become northwesterly. This shift will bring daytime
highs temps down into a range from the upper 80s to lower 90s...off
by several degrees which the area has seen recently.
Accompanying the shift to more NW flow will be several shortwaves
that will work off the Rockies on the north side of the ridge into
the Plains. Weak troughing from the surface to 850 mb will accompany
the upper level support allowing for several chance for
precipitation. With a surface ridge blocking any real advance east
off the Front Range of the aforementioned SFC/850 trough...the bulk
of expected precip will occur mainly over NE Colorado with a
possible eastward extent into the Highway 25 range.
PW values will continue to remain high...in the 1.00-1.50 inch range
during the times where precip expected...so at least there will be
potential for locally heavy rainfall with any storms. Not looking
for any issues concerning heat issues with expected highs. Low temps
will mainly range in the 60s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 935 PM MDT Tue Jul 30 2019
KGLD, vfr conditions through the period. A southwest wind around
10kts at taf issuance will veer to the west-southwest then
west at similar speeds through 15z. From 16z through 23z winds
will be variable around 6kts before establishing a southeast
direction 10kts or less.
KMCK, vfr conditions through the period. An east-southeast wind
near 10kts will continue through about 22z before backing to the
east near 10kts from 23z through the rest of the period.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...99
SHORT TERM...AW
LONG TERM...JN
AVIATION...99
Area Forecast Discussion
National Weather Service Green Bay WI
1039 PM CDT Tue Jul 30 2019
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Wednesday
Issued at 225 PM CDT Tue Jul 30 2019
The latest RAP analysis and satellite/radar imagery show high
pressure centered across the northern Mississippi Valley early
this afternoon. Cool and dry air continues to get pushed south
across the region thanks to brisk north winds. The influx of dry
air combined with diurnal mixing has caused the fair weather cu to
dissipate across north-central WI. But a large area of clouds
continues to move southeast over central to northeast WI. These
clouds should dissipate or exit for the most part by early this
evening. As high pressure settles over the area tonight, forecast
concerns mainly revolve around temperatures and fog potential.
Tonight...High pressure will become centered over the state of
Wisconsin. Lingering cloud cover should dissipate early in the
evening, which will leave clear skies and light winds across the
region. Nearly ideal radiational cooling conditions will lead to
patchy fog development late. The probabilistic guidance indicates
the highest chances will occur over the Fox Valley where dewpoints
remain in the middle 50s. But think other cold spots and low lying
areas will have potential as well since low temps are near or a
couple degrees cooler than the cross-over temps at most locations.
Cool lows ranging from the low 40s in the northwoods to the
middle 50s over the southern Fox Valley.
Wednesday...High pressure will remain directly over the area. Will
likely see few to scattered fair weather cu pop with the heat of
the day. But otherwise should see mostly sunny skies with highs in
the middle to upper 70s.
.LONG TERM...Wednesday Night Through Tuesday
Issued at 225 PM CDT Tue Jul 30 2019
The main issue in the long-term portion of the forecast will be
overnight fog potential along with precip timing/potential for the
end of the work week in to next weekend.
Wednesday night through Thursday night: A surface ridge will linger
across the western Great Lakes through this time period, keeping
fairly tranquil weather in place. Only some afternoon fair weather
CU may develop on Thursday as the area will be on the western side
of the slowly departing upper-level trough. Otherwise, look for
partly cloudy skies, generally light winds and fairly comfortable
temperatures/humidity values through this time period. Mainly clear
skies and fairly light winds overnight will allow temperatures to
drop into the 40s to low 50s for this time period. The quiet/clear
conditions will also lead to some fog potential, especially in
locations that have received heavier rainfall recently and in low
spots. High temperatures will be in the mid to upper 70s to near 80.
Friday through Saturday: The high pressure system is expected to
shift slowly off to the east and weaken through this time period,
allowing more moist/southerly flow to increase across the area. At
the same time, models are showing a trough/weak front sagging
southward toward into the area late Friday afternoon into the day
Saturday. A couple of subtle shortwaves are also progged to slide
through the area. Along and ahead of the features, chances of
showers and thunderstorms will be on the increase. The greatest
chances will be during the afternoon and evening hours as peak
heating will help to destabilize the atmosphere. In fact, models are
painting out around 1000-1500 J/kg of CAPE ahead of these features,
again, maximized during the afternoon hours. Shear values are
expected to be in the 20 to 25 knot range, so the storms would
likely be more pulse-type storms. Strong to severe potential looks
to be fairly limited and mainly during the afternoon/early evening
hours at this time. It will feel a bit less comfortable outside with
humidity values and temperatures steadily increasing. High will be
in the low to mid 80s with overnight lows in the 50s to around 60.
Saturday night into Sunday: A brief upper-level ridge is expected to
slide across the area during this time period, leading to a bit
drier conditions. A stray shower or thunderstorm can`t be ruled out
during the afternoon hours, but it looks like the coverage would be
even less than Friday afternoon and Saturday afternoon. Highs will
be in the mid 80s across the area. Overnight lows will be in the
upper 50s to low 60s.
Rest of the extended: Models are showing a deepening 500mb trough
digging into much of the central and eastern part of the country as
early as the Monday/Tuesday time period. This would be roughly
around the same time that a cold front would push through the area.
This would lead to some unsettled weather, most likely during the
Monday afternoon into Monday night time period. The trough then
lingering over the eastern half of the CONUS would likely start the
trend of below normal temperatures for much of next week.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1037 PM CDT Tue Jul 30 2019
No significant changes from previous TAF package. Generally good
flying conditions are anticipated for the next 24 hours as high
pressure settles into the region. The one concern is still the
potential for patchy fog to form overnight as temperatures drop to
near the dew points under clear skies and light winds. Will
maintain handling with a tempo group since the visibility is
likely to fluctuate due to the shallow fog layer.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......Cooley
AVIATION.......Skowronski
Area Forecast Discussion
National Weather Service Marquette MI
755 PM EDT Tue Jul 30 2019
.SHORT TERM...(This evening through Wednesday)
Issued at 409 PM EDT TUE JUL 30 2019
WV imagery and RAP analysis indicated a mid/upper level low over
James Bay and a ridge from the southern Rockies through the Northern
Plains resulting cyclonic westerly flow through the northern Great
Lakes. At the surface, high pressure centered over the Upper
Mississippi Valley was slowly building to the east. Vis loop showed
mostly sunny skies with diminishing cu over the south and east.
Tonight, As high pressure continues to build into the region,
expect favorable radiational cooling conditions with PWAT values
dropping below 0.5 inch. This will allow temps to drop into the
lower 40s inland with even some upper 30s possible in favored cold
spots. Readings closer to 50 are expected along the Great Lakes.
Wednesday, plenty of sunshine with continued dry conditions and
mixing to 4k-5k ft will push temps into the upper 70s to around 80
inland with readings closer to 70 north central near Lake Superior.
Dewpoints will also drop into the lower 40s inland with min RH
values around 30 percent. However, winds will be generally light
with prominent lake breezes developing.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 307 PM EDT TUE JUL 30 2019
Quiet, dry and slightly above normal warm weather is expected to
prevail through the middle part of the week as high pressure
continues to dominate our local weather. Friday, a weak surface
trough begins to slides down from the north and ushers in chance for
afternoon showers and thunderstorms. It does appear that sufficient
instability will build across the Upper Peninsula along and ahead of
this trough; however CAPE profiles look rather skinny and deep-layer
shear is lacking with at best 15-25 knots. While robust updrafts are
not expected, cannot rule out a pesky, pulsey storm or two Friday
afternoon. Depending on the timing/placement of the trough, we could
see additional diurnal flareups of showers/storms over the the
weekend. However, with high pressure building back in behind, the
weekend is not expected to be a washout by any means and severe
storms are not anticipated. The overall best chance for
showers/storms looks to be along the Wisconsin border.
Next week, a stronger shortwave looks to dig southeast across the
region pushing in a stronger cold front. There is still quite a bit
of uncertainty in the timing/placement of the front early to mid
next week, so NBM PoPs continue to remain very low for a longer time
period based on the uncertainty. Did not make any changes to this,
but the details certainly will become refined as we get closer.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 754 PM EDT TUE JUL 30 2019
High pressure building into the region will result VFR conditions
through the forecast period and likely for the next several days.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 409 PM EDT TUE JUL 30 2019
Winds to near 20 knots over eastern Lake Superior will diminish this
evening. Winds will then remain less than 15 knots through the
remainder of the forecast period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Ritzman
AVIATION...Voss
MARINE...JLB
Area Forecast Discussion
National Weather Service Blacksburg VA
923 PM EDT Tue Jul 30 2019
.SYNOPSIS...
A slow moving cold front will move into the Appalachians and central
mid Atlantic region tonight, then linger across the area for the
next several days. This will keep showers and thunderstorms in
the forecast through the end of the workweek and into the
weekend.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS of 923 PM EDT Tuesday...
Modified pops and weather to capture latest radar images and
trends. Needed to expand isolated showers and thunderstorms out
further east with development along outflow boundaries in the
unstable air. Most of the convection will diminish with the
loss of solar heating tonight. This is supported by the HiresW-
ARW-East, HRRR and NAM. Most of the storms will be over or
diminish around 03z, then a few showers may linger overnight
west of the Blue Ridge Mountains. Adjust temperatures with
latest obs, their trends and blended toward NBM. In general,
running cooler in the west. Added in some areas of fog overnight
especially where it rain Tuesday afternoon.
As of 730 PM EDT Tuesday...
Made some minor adjustments in temperatures for this evening
into tonight. Scattered showers and thunderstorms with locally
heavy rains will continue this evening, then taper off to
isolated showers overnight. Added areas of fog overnight.
As of 325 PM EDT Tuesday...
Scattered thunderstorms have developed early this afternoon
ahead of the slowly approaching cold front. Not a lot of dynamic
support for widespread organized convection, but outflow boundary
interaction and a moderately unstable boundary layer may help
some storms with strong gusty winds to pulse up from time to
time west of the Blue Ridge. Locally heavy rainfall is also
possible with the stronger storms and some localized hydro
issues are possible in the west.
Expect the storms to continue into this evening with a typical
diurnal trend, though forcing associated with the front will
help precipitation linger deeper into the evening and anticipate
that some showers will be around through the overnight,
especially west of the Blue Ridge. There should be some patchy
fog around especially west of the Blue Ridge tonight but
lingering cloudiness should help limit cooling and prevent the
fog from becoming more widespread.
With the frontal boundary over the region tomorrow expect
another round of showers/thunder aided by short wave energy
along the boundary. Higher precipitable water values will also
support some torrential downpours but dynamics are still
lacking for organized convection so the severe/hydro threat will
remain localized.
Temperatures tonight will remain mild with readings in the 60s.
Highs tomorrow will be just a touch cooler with readings near 90
east of the Blue Ridge, lower generally 80s to the west.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 300 PM EDT Tuesday...
An upper-level trough positioned near or just west of the
Blacksburg forecast area will make little eastward progress
during this period. A surface cool front will stall in the
southern/eastern part of the CWA or just south of the CWA. It
will eventually dissipate across the NC/TN vicinity by the end
of the week as upper flow aloft becomes increasingly weak and
diffuse. Late in the week, some enhancement to subtropical
moisture (PWATs between 1.5-1.75") associated with low-level
southeast trajectories around a Bermuda ridge and perhaps even
some moisture from a weak tropical system off/along the
southeast U.S. coast (e.g., invest 95L?) could enhance the
rainfall across the region, and increase the threat for hydro
related issues.
Considerable cloud cover, along with scattered to numerous
showers and thunderstorms that will tend to follow typical
diurnal convective frequency and strength trends are quite
likely. Given increasing amounts of tropical moisture through
the week and weak troughing aloft, scattered showers and
isolated thunderstorms may continue even during the
overnight/early morning hours, especially later in the weak. The
GFS and ECMWF remain at odds with respect to amounts and
placement of the heaviest rainfall as well as from run-to-run.
However, the ECMWF consensus has been that the heaviest rainfall
will be east of the Blue Ridge and later in the period, while
the GFS implies the heaviest rainfall will be closer to the
spine of the Appalachians and earlier in the period. The ECMWF
has been more consistent from run-to-run and seems more in line
with the expected placement of the trough, stalled front, and
any tropical moisture plume. Have kept pops mostly in the 50-60%
range through the period, which can be refined to higher or
lower values as needed as we draw closer to the period in
question.
Any area(s) that see repeated periods of rain could see some
short- fused hydro issues, in particular on Thursday into Friday
when PWATs start to rise. While the large-scale pattern remains
relatively stagnant, individual storms should be moving along
and unfavorable antecedent conditions (high FFG) don`t presently
support a significant flood threat at this point. Will have to
re-evaluate the hydro situation moving with time as the FFG
values are likely to lower a bit each day as accumulated
rainfall totals mount up over the next few days. Will continue
to highlight this threat via the HWO and the hwo for now.
With respect to the severe threat, feel like today is honestly
the best threat for such as heating and instability will be
inhibited from abundant cloud cover and precipitation throughout
most of the period. SPC has just advertised general thunder for
the most part the next few days.
The cloud cover, tropical moisture, and precipitation will keep
overnight minimum temperatures well above normal in the muggy
mid 60s mountains to lower and even a few mid 70s Piedmont. By
the same token, daytime temperatures will be held down for the
same reasons. Highs will be mostly mid 70s mountains to lower
and mid 80s Piedmont. Of course, any brief periods of sunshine
could boost a few spots across the Piedmont to near 90F at least
briefly.
/Confidence in Forecast Parameters/
Temperatures - High,
Precipitation Probabilities - Moderate to High,
Winds - High,
Thunderstorm Threat - Moderate.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 315 PM EDT Tuesday...
Little to no change in the overall synoptic pattern across the
U.S. is expected during the longer range periods. A massive
hot upper ridge will dominate the western U.S. with general and
broad troughing in the east. A weak frontal boundary separating
true tropical air from semi-tropical air will likely linger
through the weekend and into early next week across the TN
Valley and into the Carolinas. The flow aloft will be northwest
and a series of weak disturbances will likely traverse the flow
and enhance convection from time-to-time. Given the warm, moist,
atmosphere remaining in place across the region, development of
showers and a few thunderstorms will be easy to come by. As the
upper trough axis drifts a bit further east next week, the
coverage of convection should decrease a bit, but remain in the
chance to high chance category as literally no change in the air
mass or overall synoptic pattern is expected.
The main concern going into the weekend and early next week will
be the growing threat for heavy rain and localized flooding.
With tropical moisture or at least semi-tropical moisture in
place and weak steering currents, thunderstorms/showers will be
efficient rain producers and areas that see repeated rainfall
day-after-day or where thunderstorms persist over a short period
of time, could trigger localized flooding.
Little change in temperature is expected during the period as
well with low temperatures in the 60s west to the 70s east with
high temperatures held mainly into the 70s mountains and 80s
Piedmont. Humidity levels will be high, so it will basically
feel pretty muggy.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
As of 740 PM EDT Tuesday...
As a cold front slowly approaches from the west, scattered
showers and thunderstorms will continue this evening into
tonight. Then, the convection will diminish with the loss of
solar heating tonight, a few showers will linger during the
overnight, especially west of the Blue Ridge. Some of the
rainfall will also be heavy and reduce flight categories to
MVFR/IFR. Winds near thunderstorms will be variable and gusty.
Winds outside of storms will generally be light.
The combination of light winds and low level moisture
will result in areas of fog overnight into Wednesday morning.
KLWB has the best chance for IFR/LIFR fog. MVFR fog is possible
where it rained Tuesday afternoon.
Any morning low clouds and fog will lift by mid Wednesday
morning. MVFR convection will fire once again on Wednesday with
VCTS for the latter portion of the TAF period.
Medium confidence in ceilings,visibilities and winds during the
taf period.
.Extended Aviation Discussion...
A cold front will remain stalled over the area through the end
of the week. Scattered to numerous showers and thunderstorms
with periods of sub-VFR ceilings can be expected through
Sunday. This pattern will also result in an increase in MVFR or
lower clouds and MVFR fog due to moist low levels.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...MBS
NEAR TERM...KK/MBS
SHORT TERM...RAB
LONG TERM...RAB
AVIATION...KK/MBS
Area Forecast Discussion
National Weather Service Las Vegas NV
845 PM PDT Tue Jul 30 2019
.SYNOPSIS...Shower and thunderstorm chances will increase tonight
into Wednesday, with Wednesday having the highest chances for
precipitation. Below average temperatures will accompany the
moisture surge. Rain chances will diminish Thursday and through the
weekend as temperatures slowly climb back to normal.
&&
.EVENING UPDATE...
Still expecting a brief lull in convection tonight before more
widepread development across Mohave County and southeastern NV
occurs overnight and tomorrow morning.
Still seeing broad upper level ascent due to the right entrance
region of a jet streak developing west of the Colorado River. While
HRRR trends are quite dry compared to other CAMs, still believe the
very moist atmosphere, broad ascent, MCV interaction, and multiple
outflows present, will aid in re-development overnight and through
much of the morning tomorrow. Decided to increase PoPs where we
already had them for Mohave and eastern Clark counties while also
extending slight chance PoPs as far west as Twentynine Palms.
Also decreased PoPs a bit for late tomorrow afternoon and evening as
moisture should quickly exit to the northeast. Populating with
latest CAM guidance supports this idea as well.
.DISCUSSION...through next Tuesday.
Satellite showing extensive area of clouds across Mohave County with
a few lightning strikes north of the Colorado River. Elsewhere,
skies are mostly sunny.
Low level moisture continues to spread northward today with surface
dewpoints in the 50s as far north as Lake Mead. The Las Vegas Valley
looks to be right along the leading edge with dewpoints in the mid
40s to lower 50s primarily east of I-15, while some readings in the
lower 30s exist along the western foothills and Red Rock Canyon.
Some features of interest are an inverted trough over the northern
Gulf of California. There are two smaller scale circulations over
southwest and southeast Arizona.
Greatest coverage in thunderstorms the rest of today and this
evening will be along the Mogollon Rim and south central Arizona
Deserts. Limited instability over Mohave County should limit
coverage to isolated at best. Evening shift will need to monitor
potential outflows from Arizona storms that could trigger additional
storms in the late evening and overnight hours.
Models remain consistent lifting the inverted trough north across
western Arizona Wednesday. Additional forcing from approaching jet
streak depicts pocket of favorable divergence aloft lifting over
eastern Mohave County. Held off on a Flash Flood Watch as all
synoptic scale models suggest greatest rainfall totals staying just
east of Mohave County. West of the Colorado River in southeast
Nevada and eastern San Bernardino County storms will be isolated to
scattered in coverage.
Drier southwest flow will gradually overspread the area Thursday
into the weekend. Over the weekend any remaining threat of
thunderstorms will be over northwest Arizona. After a brief reprieve
from the hot temperatures Wednesday and Thursday values will warm
back to above normal this weekend. Moisture may push back west early
next week for threat of storms returning to southern Nevada and
eastern California.
&&
.AVIATION...For McCarran...Southeasterly wind gusts to 25 kts will
persist through the remainder of the afternoon before decreasing
going into the evening. Southeasterly wind speeds around 10 kts
expected to continue through the overnight hours before ramping back
up mid-morning Wednesday and lasting through the afternoon.
Confidence in wind speed and direction Wednesday is low as isolated
showers and thunderstorms are possible. These may kick off outflow
winds from northwestern Arizona that are subject to impact the
terminal. Low, broken CIGs aoa 10 kft expected to increase overnight
into the morning with vicinity showers possible in the morning and
vicinity thunderstorms possible through the afternoon.
For the rest of southern Nevada, northwest Arizona and southeast
California...Gusty south-southeasterly winds 20-25 kts will persist
through the remainder of the afternoon for the southern Nevada and
northwestern Arizona TAF sites. Wind speeds are expected to decrease
late-afternoon but will persist around 10-15 kts through the night.
Confidence in wind speed and direction Wednesday is low as isolated
showers and thunderstorms capable of kicking off outflow winds are
possible. Highest chances exist in northwestern Arizona, though pop-
ups in southern Nevada and southeastern California cannot be ruled
out. Vicinity showers and thunderstorms possible tonight into
Wednesday morning for the Colorado River Valley sites beginning
around 06Z and lasting through the day. Associated broken clouds
will lower through the overnight hours to around 10 kft through the
remainder of the TAF period for northwestern Arizona and southern
Nevada TAF sites. Southeastern California TAF sites expected to stay
dry with increasing mid-level clouds through the period.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
DISCUSSION...Pierce
AVIATION...Varian
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