Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/08/17
Area Forecast Discussion
National Weather Service State College PA
1051 PM EDT Mon Aug 7 2017
.SYNOPSIS...
Low pressure will continue to move away from the Mid Atlantic
Coast tonight. High pressure will bring dry and more
seasonably cool temperatures for Tuesday and Wednesday.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Little more than an isloated shower or scattered sprinkle is
left over as the mid level shortwave traverses the region.
The HRRR lingers a few light showers into the wee hours over the
south, but the trend will be for drying as high pressure builds
back into the area. Initially cloudy skies will transition to
partial clearing late. Patchy fog is possible after midnight
through the sunrise hours of Tuesday, but a developing light NNW
breeze could thwart fog formation if the breeze can become well
established.
Temps will fall to the mid 50s NW to low 60s in the SE tonight.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
High pressure gradually builds in from the west Tuesday-Wed.
Sct-bkn stratocu and areas of mdt cu will be found across much
of the region Tuesday under NW llvl flow and 100-300 j/kg of sfc
based cape.
A sprinkle, or brief shower over the higher terrain is possible
across the north in the morning. Otherwise...dry conditions are
in the fcst. Maxes Tues in the 70s, and maybe touching 80F
across parts of the SE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Further improvement will be seen Tuesday night as high pressure
sprawling from the midwest through the Ohio Valley builds over
western Pennsylvania by 12z Wednesday. The surface high will
provide a pristine day on Wednesday as it traverses the
Commonwealth, and then moves offshore on Thursday allowing
temperatures to start rebounding from several days of well below
normal. Even with the moderation..expect highs for Wed and Thu
to remain slightly below normal. Enough moisture return on the
western periphery of the offshore ridge may allow scattered
afternoon showers or thunderstorms to develop Thursday and
Friday...but it appears most will remain dry. Slow moving
frontal system brings a better chance for shra/tsra on Sat and
Sun with unsettled conditions prevailing into early next week as
an anomalous upper trof progresses through eastern Canada...and
the base of the upper trof aligned from NE to SW keeps cyclonic
flow and favorable moisture over the the region for at least
scattered convection.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Surface low east of the area this evening with the upper trough
sliding through overnight. This will keep a few areas of light
showers around through 04z-06z as they gradually weaken.
Ceilings will remain restricted into the overnight just about
everywhere, though partial clearing may begin to work in late
as NNW breeze picks up off the surface late. Patchy fog is
possible after midnight through the sunrise hours of Tuesday.
High pressure gradually builds in from the west Tuesday. After
lower clouds mix out early, VFR conditions should be the rule as
NW flow picks up to around 10 mph.
Patchy fog poss mainly in the northern valleys Tue night, with
another VFR day in store for Wed.
.OUTLOOK...
Tue...Areas of low clouds early, then improving to VFR.
Wed...No sig wx.
Thu...Scattered mainly afternoon SHRA/TSRA poss west.
Fri-Sat...Scattered SHRA/TSRA.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...La Corte
NEAR TERM...La Corte
SHORT TERM...Lambert
LONG TERM...DeVoir
AVIATION...RXR
Area Forecast Discussion
National Weather Service Green Bay WI
1030 PM CDT Mon Aug 7 2017
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Tuesday
Issued at 301 PM CDT Mon Aug 7 2017
Skies were partly sunny across the north and mostly sunny across
central into east-central Wisconsin. Temperatures were in the 70s.
The latest radar images indicated a shower had developed across
northern Oconto County during the past hour.
For the remainder of the afternoon into early this evening, HRRR
model and NAM12 develop isolated showers and perhaps a thunderstorm
across far northeast Wisconsin during the remainder of the
afternoon. The showers and storms should drop slowly southeast.
Will continue the chances of showers and isolated thunderstorms
into early this evening with the highest chances across Marinette
and Oconto Counties. Some of the showers and storms could make it
as far south as Green Bay. The showers and storms should end by 9
pm, then mostly clear skies are expected for the remainder of the
night. There could be a few patches of fog, especially at the
airport sites in Vilas County. Based on current surface dewpoints
and expected clear skies later tonight along with light winds,
lowered minimum temperatures at most places.
On Tuesday, any patchy fog should burn off by 9 am. Skies will
become partly cloudy across much of the region. There is a small
chance of showers across far northeast Wisconsin. Did raise high
temperatures a few degrees based on the latest numerical guidance
values.
.LONG TERM...Tuesday Night Through Monday
Issued at 301 PM CDT Mon Aug 7 2017
Models agree to a good extent through Thursday but
then differ as to the extent of closing off an upper low over the
Great Lakes region. Dry weather should continue until Wednesday
afternoon with northwest upper flow and surface high passing by to
the southwest. Temperatures and dewpoints will increase a couple
degrees each day but should remain relatively comfortable.
The upper flow becomes westerly and then southwest as an upper
trough moves southeast from central Canada Wednesday night and
Thursday. Increasing low level moisture and convergence combined
with upper diffluence should make for a large area of showers and
thunderstorms.
The system should exit by early Friday, but scattered showers are
possible Friday afternoon through Saturday depending on what happens
with the upper low. Should be a little cooler Saturday and Sunday.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1025 PM CDT Mon Aug 7 2017
High pressure will bring VFR conditions to most of the forecast
area during the period, with the possible exception of patchy
MVFR/IFR fog in north central and far northeast WI overnight.
Increasing boundary layer winds should prevent any dense fog from
occurring. Scattered showers and thunderstorms may also briefly
restrict visibility in localized areas of far northeast WI Tuesday
afternoon.
Gusty west winds will develop at the surface during the late
morning and afternoon on Tuesday, but the gusts should remain
below 20 knots.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....Eckberg
LONG TERM......RDM
AVIATION.......Kieckbusch
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
900 PM EDT Mon Aug 7 2017
.SYNOPSIS...
Low pressure will pass south of the region tonight bringing a
round of showers and a few thunderstorms. High pressure will
build back into the region on Tuesday with drier air and
temperatures a bit below seasonal norms. A weak cold front will
drop towards the region on Wednesday...and stall over the area
through Thursday. This will bring the threat of showers and
thunderstorms to the mountains and foothills along with
seasonable temperatures. Somewhat drier weather is expected to
return for Friday.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
9 PM Update...
Scattered showers are still ongoing along a weak front
stretched across the foothills of NH and ME and a surface trough
farther south in southern NH and extending into the Gulf of
Maine. Temperatures north of the front are in the mid 50s while
to the south readings are in the upper 60s to lower 70s. Have
removed thunder from the forecast as the potential for lightning
continues to decrease with the loss of daytime heating.
Adjusted PoPs based on latest HRRR which continues to diminish
convection the next couple of hours before showers increase
spatially with the approach of the next short wave. Also added
fog to the waters and a few mountain valleys.
515 PM Update...
Updated to adjust PoPs and temperatures for current observations
and trends. Scattered thunderstorms have developed mainly over
central NH and NW Maine. The main threat is heavy rain with
convection expected to dissipate in 2-3 hours.
Previous discussion...
A s/wv trof across the Mid Atlantic is forcing an area of
rainfall mainly S of New England this afternoon. To the N over
our forecast area...clear skies to start the day have allowed
temps to warm well into the 70s to near 80. A strong s/wv
upstream across the Great Lakes has supported WAA aloft and
moisture pooling along the mid level warm front near the
Canadian border. The coupled diurnal heating and the moisture
aloft has overcome meager lapse rates to produce convection from
the Adirondacks thru the White Mtns and into central ME. That
trend will continue thru the evening...especially as 100 kt jet
streak approaches and provides a little more diffluence aloft.
Surface instability and effective shear values are on the low
side for strong...organized storms...but some thunder is likely.
I do expect the strongest storms to remain below severe
thresholds...but some locally heavy rain is possible.
Gradually more widespread forcing for ascent will develop as the
second s/wv nears the area tonight. Light rain will overspread
the area from SW to NE as that lift increases. While convection
off or near the Srn New England coast will wring out most of the
moisture...there is enough forcing for at least a wide band of
rainfall across portions of the GYX forecast area. Model
guidance is in fairly good agreement on a nearly W to E band of
rain forming near midnight and then gradually wrapping into
developing low pressure by morning. This should be enough for a
fairly widespread 0.25 to 0.50 inch rainfall. A good drink...but
less than previous forecasts as the greatest instability and
moisture have shifted S today.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Low pressure moves Ewd early Tue...and steady rain will come to
an end from NW to SE. The main s/wv trof will not cross the
region until Tue afternoon...so the threat of showers is still
in the forecast until that trof axis passes. Any amount of
heating behind the departing rainfall will make afternoon
showers more likely.
Otherwise the trend will be for drying and clearing into the
evening. Weak surface ridging and neutral heights are expected
Tue night. So recent rainfall and cooler temps may allow for
some valley fog to form...which could be locally dense.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
High Impact Weather Potential: Marginally severe thunderstorms
possible Wednesday and Thursday afternoons...away from the coast.
Pattern: A look at early afternoon water vapor reveals a large
pinwheel south of the Aleutian islands which is dominating much of
the flow pattern over the northeastern Pacific. This slow-moving
feature provides an anchor to the downstream pattern...with a ridge
along the west coast of North America and downstream troughing over
northeastern North America. There is strong deterministic/ensemble
support for the general flavor of this pattern remaining unchanged
through the long term forecast period. The cutoff low will push
slowly towards the west coast of North America...building the
downstream ridge /with this feature very slowly edging east/ with
troughing in our vicinity largely remaining centered west of our
longitude.
Pattern Implications: While troughing will dominate the large scale
pattern over the eastern half of North America...heights will be
near seasonal norms...and with the actual trough axis west our
longitude...see no reason for temperatures to stray much from
seasonal norms.
The Details...
Wednesday-Thursday: As has been advertised for a few days...a
weak cold front will settle south towards the region on
Wednesday... becoming parallel to the mid level flow and
stalling as a result through Thursday. While this boundary is
not all that impressive...it will bring with it a modest uptick
in moisture...with PWATs climbing back to around 1.25 inches.
Mid level forcing is lacking...so expect any afternoon shower/
thunderstorm activity to be isolated to perhaps scattered at
best...and likely confined to the mountains...where some upslope
assistance working in tandem with the frontal boundary will
bring the best chance for convective initiation. CAPE values
suggest that thunder is possible both days...with H5 flow around
30kts suggesting that if there is any severe threat...it will
be very isolated with little in the way of convective
organization. T8s hover around +10-13C from north to south which
should allow for highs in to reach the mid 70s north to lower
80s south.
Friday: Next shortwave rotating around the base of longwave
troughing will move into the Great Lakes region Thursday night
and Friday...which will cause the mid and upper level winds to
back over our region...taking any remnants of the stalled
frontal boundary back north with southerly flow taking over.
With this change to the flow...PWATs may initially decrease as
drier air south of the stalled frontal boundary lifts back
north. This...combined with little in the way of low/mid level
forcing suggests relatively low threat for additional
shower/storm activity. Temps aloft will warm over northern areas
with the lifting front...but change little over southern
areas...so highs around 80 north and into the lower and middle
80s south with cooler values along the ME coast given good setup
for robust seabreeze.
Saturday-Monday: Unsettled will characterize the end of the long
term forecast period as two shortwaves embedded within the
longwave trough rotate through the region. The first one arrives
in the Friday Night-Saturday timeframe with the next Sunday
night and Monday. Saturday and Sunday the aforementioned Great
Lakes shortwave moves north and east with attendant surface low
following suit. Some discrepancies at this range as to whether
a wave of low pressure will attempt to form at the coast
/bringing a more concentrated area of rainfall/ model skill in
this regard is really questionable at this range and feel it/s
more prudent to indicate a chance of showers throughout the
region. With offshore high pressure... south/southeasterly flow
may spell for some marine stratus through the weekend. This
setup would likely keep us too stable for thunder and will not
include mention in this forecast package. To end the forecast
period Monday...it appears that the remainder of any shortwave
energy will push through the region...with flow becoming
southwesterly with perhaps a better thunder chance given the
over- land trajectory. Still...much too early to include more
than chance PoPs.
Temperatures aloft of +11-14C would support highs in the upper
70s to mid 80s from north to south /a few degrees above
climatological norms/ but potential cloud cover suggests
keeping forecast closer to climatology until we can better
refine which day will feature the most sun.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Short Term...Early this evening SHRA/TSRA will be possible in
the mtns...especially at HIE and to a lesser extent LEB. TEMPO
IFR conditions are possible with any convection. Overnight -RA
overspread much of the Srn two thirds of the forecast
area...with widespread MVFR conditions. Areas of IFR are
possible...but confidence is lower based on lower likelihood of
heavier rainfall amounts at this time. Conditions improve to VFR
by Tue afternoon. Cooler temps and recent rainfall Tue night may
allow for some areas of fog to form in the favored river
valleys...which would lead to local LIFR conditions...especially
LEB and HIE.
Long Term...Generally VFR conditions expected through Friday
with some potential for restrictions in afternoon showers and
thunderstorms in the foothills and mountains Wednesday and
Thursday afternoons. More widespread restrictions will be
possible this weekend in showers...and the potential for marine
stratus...particularly on the coast.
&&
.MARINE...
Short Term...SCA for hazardous seas remains in effect
overnight...as Sly flow increases and builds seas ahead of low
pressure. Winds shift Tue...and seas gradually diminish early in
the day. Winds and seas remain below SCA thresholds Tue night.
Long Term...Winds/waves are expected to remain below small
craft levels through the remainder of the week and likely the
coming weekend.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory for hazardous seas until 8 AM EDT Tuesday
for ANZ150-152-154.
&&
$$
NEAR TERM...Hanes
SHORT TERM...Legro
LONG TERM...Arnott
Area Forecast Discussion
National Weather Service Houston/Galveston TX
1016 PM CDT Mon Aug 7 2017
.UPDATE...
Though the radar quieted down for several hours as the atmosphere
had been pretty well worked over in the wake of rain earlier
today, it is now beginning to spark back to life. A mesoscale
convective vortex (MCV) has been very conspicuously spinning in
the area of College Station, drifting roughly to the ESE at 15 or
so knots. Additionally, onshore flow is resuming from the coast -
the quality of this return flow is made very apparent by the
sparking of showers along the coast in the last hour or so near
what is effectively a frontal boundary between unstable Gulf air
and the depleted air from earlier today.
To date, the new showers along the SE edge of the MCV have been
only sporadically impressive. Though boasting individual cores
with instantaneous dual pol rates of 4+ inches per hour, the
surrounding areas have been pretty light, and with pretty quick
individual cell motion being pretty quick, the highest of MRMS one
hour QPE are isolated pixels a tad over 1 inch. That said - as the
influx of more unstable air continues, and flow aloft weakens and
veers to be more line parallel, these characteristics should
change for the worse.
Though performance from the CAMs lately has been pretty lousy, it
seems to have had a not awful handle on this MCV, and so am
reluctant to abandon its guidance entirely. Recent HRRR runs seem
to peg out in the 5 inch neighborhood for QPF. The experimental
HRRR time lagged ensemble shows a relatively strong signal for
exceeding 3 inches of rainfall in a 6 hour period, and a slight
hint in this convergent area for exceeding 6 inches. Though it`s
not yet matched in rain occurring, think 2ish inches per hour and
isolated spots of 3-5 inches accumulation seems reasonable given
that factors should come to support heavier rainfall. This should
be capable of causing some localized flooding issues at the least.
The really big question is where the heaviest rain will come down.
With the MCV motion, this preferred area for rainfall will be
drifting slowly towards the Houston metro, with storms already
occurring in extreme NW Harris County. At this time, think the
line motion is slow enough that its location that the heaviest
rain will fall northwest of the more vulnerable urban locations.
However, a faster drop of the line, or if significant rain starts
developing in the inflow, and that scenario could change.
For further information, please visit the WPC website and read
Mesoscale Precipitation Discussion 651.
Luchs
&&
.PREV DISCUSSION... /ISSUED 638 PM CDT Mon Aug 7 2017/
AVIATION...
With a weak circulation center close to the CLL area early this
evening, we`ll need to carry VCSH/VCTS in all of our 00Z TAFS for
possible overnight through early morning development. Will amend
with more details once we get a better idea of where activity
develops. Generally expect VFR conditions outside of the rain areas,
and MVFR/IFR ceilings and visibilities with the storms. Should
see mostly light and variable winds tonight and tomorrow. 42
PREV DISCUSSION... /ISSUED 258 PM CDT Mon Aug 7 2017/
DISCUSSION...
Bit of a difficult forecast for tonight. The airmass could be
fairly worked over; although, both the NAM and the GFS slow down
the upper level trough to the point it is nearly stationary over
the Upper Texas coast tonight and Tuesday. The ECMWF on the other
hand is fairly progressive with the trough and shows it moving off
of the coast tonight. Because the flow pattern is actually fairly
light aloft, am inclined to lean toward the slower GFS and NAM.
Short term and high resolution models have had a problem with
initializing. The latest Texas Tech WRF shows the rain and
thunderstorms diminishing during the evening with redevelopment
Tuesday morning. Decided to go with a blend of the models but with
the caveat that the forecast may be updated drastically later this
evening.
Scattered showers and thunderstorms still are a good bet on
Tuesday given the weakness aloft that will lead to instability
with daytime heating. The upper level high pressure ridge will
then build overhead Tuesday night and Wednesday. The building
ridge will lead to lessoning rain chances and warmer daytime
temperatures, meaning that daytime heat index values may reach
into the 105 to 107 range by the end of the week. Friday could
see higher values with low-level moisture from the Gulf of Mexico
moving under the high pressure ridge aloft.
MARINE...
Light/moderate southerly winds will prevail this evening/tonight but
the passage of a weak frontal boundary should produce a brief period
of very light N/NW winds early Tuesday morning. However, the onshore
flow is expected to return by tomorrow afternoon. Periods of showers
and thunderstorms are expected across the coastal waters for much of
the week as a series of disturbances move across the area. Winds and
seas will be higher in/around these storms.
Marine interests should continue to monitor the progress of Tropical
Storm Franklin as it moves westward across the Yucatan Peninsula and
into the Bay of Campeche towards the middle of the week. Franklin is
likely remain to the south of Texas, but increased swell could begin
impacting the offshore waters as early as Wednesday. Seas will range
from 4 to 7 feet by Weds night through Thurs before gradually taper-
ing off into the weekend. 41
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 75 90 75 94 75 / 70 40 40 30 20
Houston (IAH) 76 90 75 93 77 / 70 50 30 40 20
Galveston (GLS) 80 89 81 90 81 / 30 40 20 30 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk until 11 PM CDT this evening for the
following zones: Brazoria...Chambers...Galveston...
Matagorda.
GM...NONE.
&&
$$
Discussion...25
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
905 PM CDT Mon Aug 7 2017
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
Latest satellite rap imagery showed another shortwave approaching
from the west. There was also a frontal boundary north of the
region. For now showers were decreasing in coverage from the
west. Hires models shows redevelopment coming in from the west
later tonight which will bring some locally heavy rainfall across
the north half of the region with our 2 inch pwat airmass. So
will continue the current Flash Flood Watch area for the remainder
of the night. So Adjusted pops for the rest of the night.
Overnight lows will be in the lower 70s./17/
&&
.AVIATION...
00Z TAF discussion:
Early this evening showers and some thunderstorms were continuing
across the forecast area. Expect more shower and thunderstorms
redevelopment prior to dawn across the delta region. This will
continue to bring periods of ceiling and visibility restrictions
to the taf sites during the night. Expect low stratus to develop
IFR ceilings for late tonight into Tuesday morning./17/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 73 80 72 85 / 51 73 49 61
Meridian 73 81 72 85 / 72 69 46 64
Vicksburg 73 81 72 86 / 43 76 53 56
Hattiesburg 74 85 73 87 / 60 59 38 61
Natchez 73 82 72 86 / 38 75 50 54
Greenville 72 81 71 84 / 71 62 50 52
Greenwood 72 80 71 84 / 65 73 55 59
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Flash Flood Watch until 7 AM CDT Tuesday for MSZ018-019-025>053.
LA...Flash Flood Watch until 7 AM CDT Tuesday for LAZ007>009-015-016-
023>025.
AR...Flash Flood Watch until 7 AM CDT Tuesday for ARZ074-075.
&&
$$
17
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
940 PM EDT Mon Aug 7 2017
.SYNOPSIS...
A cold front will cross the area overnight and Tuesday and stall
south of the region Tuesday night into Wednesday. The front
will lift north as a warm front Thursday. High pressure will
gradually build over the southeast coast by next weekend as a
trough lingers over the Coastal Plains.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of 640 PM Monday...As expected convective activity has
decreased in coverage and intensity with the loss of diurnal
heating this evening. There should be a minimum in coverage for
the remainder of the evening hours, then as the cold front
approaches after midnight, showers and thunderstorms should
redevelop along and ahead of it across the north and west
counties. The models also indicate that an area of convection
will develop along the coast well ahead of the front. Thus will
feature chance PoPs through late evening, then increase to
likely all areas after 6Z which is in line with a consensus of
the models. Locally heavy downpours will be the main threat
overnight as PW values are forecast to exceed 2". Muggy
overnight lows in the low to mid 70s inland and mid to upper 70s
coast are expected.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
As of 240 PM Monday...Numerous showers and embedded
thunderstorms will accompany the cold front across the region on
Tuesday and have raised PoPs to categorical area-wide as most
every location should receive measurable rain on Tuesday.
Instability will be more modest on Tuesday with CAPE values only
about 1000-1500 J/kg and LI`s only around -1 or -2, so expect
only embedded mostly elevated convection. With minimal sunshine,
high temperatures will only rise to the lower 80s, following
muggy lows in the mid 70s for Tuesday. Rainfall amounts of one-
half to locally one-inch will be possible given precipitable
water values of 2 to 2.5 inches.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
As of 330 PM Mon...Most of the week will be unsettled as the
region will be under cyclonic flow aloft and above climo PW`s.
Tuesday Night through Wednesday....The exception to the
unsettled pattern will be this period, as cool front will pass
completely through E NC by Tue evening. Some lingering showers
and an iso storm could be found across southern zones, though
most areas will be drying out. Cooler and drier air filter into
the region with TD`s falling through the 60s. Lows Tue night
pleasant in the mid/upr 60s. Removed pops further for Wed, with
chance pops relegated to the southern half, where some sct
overrunning showers may exist as 850mb flow is still southerly
with NE sfc winds. Highs Wed will be pleasant with readings in
the low 80s area wide.
Thursday through Sunday...Better precip chances come back on
Thursday as the aforementioned front lifts north as a warm
front, though due to convective nature of the precip, will
continue to cap pops at 40-50 percent for now. Highs moderate
back into the mid 80s.
Friday through Monday...Similar situation for Friday through
early next week, though best pops will be inland from the coast
as mid Atlantic ridge begins to build towards E NC and thermal
trough develops across the Piedmont. Temps will climb back
closer to climo with highs in the mid/upr 80s.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Short Term /through Tuesday/...
As of 640 PM Monday...Expecting a period of VFR conditions this
evening outside of diminishing scattered showers and
thunderstorms. Then after midnight precipitation is expected to
increase again as the cold front approaches. Ceilings are also
expected to lower to MVFR levels. The HRRR and BUFKIT NAM
soundings bring these lower ceilings in as early as 4Z, but will
hold off until after 6Z when the precipitation coverage is
expected to increase. Expecting prevailing MVFR or worse
conditions for much of Tuesday as scattered to numerous showers
and thunderstorms with torrential downpours occur across the
area.
Long Term /Tuesday Night through Saturday/...
As of 330 PM Mon...VFR conditions will prevail most of the
TAF period. However, tempo sub VFR conditions as showers and
thunderstorms are forecasted each afternoon/evening Thur through
the weekend. Areas where it rained will be susceptible to
patchy ground fog and periods of sub-VFR conditions during the
early morning hours each day.
&&
.MARINE...
Short Term /Tonight and Tuesday/...
As of 640 PM Monday...SW winds of 20 to 25 knots will continue
over the Pamlico Sound and the bear shore waters tonight as the
cold front approaches from the north. Per latest NWPS/SWAN
model, seas will build as high as 6 to 8 feet later tonight into
Tuesday. The cold front will enter the far northern waters
toward morning and slowly work north to south during the day
with winds shifting to N during the day on Tuesday. Winds will
start to diminish in the afternoon, but seas will remain
elevated until at least 00Z on Wednesday.
Long Term /Tuesday Night through Saturday/...
As of 330 PM Mon...Winds will become NE as high as 15 knots
after the frontal passage on Tue evening and then remain in the
10 kt range through Wednesday. Seas will subside to 2-4 ft
Tuesday night and then 2-3 ft for the rest of the week. The
front will lift north as a warm front on Thursday with winds
switching back to the southeast generally around 10 knots.
Winds then become S to SW and increase a bit into the 10-15 kt
range Friday into the weekend as high pres builds towards the
coast and a trough remains inland.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Beach Hazards Statement from 8 AM EDT Tuesday through Tuesday
evening for NCZ095-098-103-104.
MARINE...Small Craft Advisory until 8 AM EDT Tuesday for AMZ135-150.
Small Craft Advisory until 8 PM EDT Tuesday for AMZ152-154.
Small Craft Advisory until 5 PM EDT Tuesday for AMZ156-158.
&&
$$
SYNOPSIS...JME/CTC
NEAR TERM...JME/CTC
SHORT TERM...CTC
LONG TERM...TL
AVIATION...JME/CTC/TL
MARINE...JME/CTC/TL
Area Forecast Discussion
National Weather Service Blacksburg VA
902 PM EDT Mon Aug 7 2017
.SYNOPSIS...
Low pressure progressing east northeast over central West
Virginia will continue through the mid Atlantic states tonight
before exiting into the Atlantic Ocean early Tuesday. This will
bring a cold frontal boundary through the area early on Tuesday
with high pressure settling in during the evening hours. The
frontal boundary is expected to push back north later in the
week, once again introducing precipitation chances to the
forecast area.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 845 PM EDT Monday...
Bands of mostly heavy rain producing showers and storms continue
across southern/eastern sections tonight, just south of a slow
moving surface front that lingers across the mountains. Ahead of
the boundary, still seeing some instability linger over the
southern half given Pwats of around 2 inches per GSO evening
raob, and more of a southwest trajectory. Latest short term
solutions continue to key in on more organized convection taking
shape espcly piedmont overnight, where the HRRR has heavier
rainfall lingering along 85h residual theta-e ridging until
just before dawn. Thus upping pops to categorical for a few more
hours southeast sections including a heavy rain mention.
Elsewhere will gradually trim back pops from northwest to
southeast overnight, overall similar to the previous forecast at
this point. Given cloudy skies overnight and very moist
conditions, expect some locations to remain in the 70s for lows
espcly east. Therefore nudged up in spots closer to the latest
Lav numbers overnight.
Previous valid discussion as of 300 PM EDT Monday...
Current surface observations show a warm/stationary front draped
nearly west to the east across the interstate 64 corridor in
WV/VA and a cold front hanging northeast to southwest across
central TN/KY. In between these boundaries, scattered showers
with a few rumbles of thunder continue to impact portions of the
forecast area, dropping locally heavy rainfall. These showers
and storms are expected to continue through the remainder of the
afternoon and evening as the frontal boundaries progress
eastward.
Axis of heaviest precipitation should shift slightly east this
during the evening hours, focusing along and east of the Blue Ridge
Mountains where better instability and higher Pwat values (2 -
2.25 inches) are located. Here, additional accumulation amounts
could range from a half inch to three quarters of an inch, with
amounts potentially exceeding an inch in a few isolated spots.
Luckily, with dry antecedent conditions, ponding of water and/or
flooding should remain isolated as we head into the overnight
hours, however, this could change if persistent downpours train
over the same areas.
The severe weather threat has been quiet thus far, but a few
breaks in the cloud deck in the warm sector has allowed for
1000 J/KG MUCAPE to form along and south of US 460. This,
combined with modest shear could be enough to support a few
potentially strong storms this afternoon/evening, located
primarily close to the VA/NC state line. Short term models have
the cluster of showers/storms moving out of eastern TN/KY as
being the primary forcing mechanism of these potential storms,
and remain rather bullish with their potential, especially
between 6pm - 8pm.
Tonight, heaviest rain/storm chances come to an end slowly NW
to SE as the boundary pushes through. This trend seems to be
persistently slowing with each model run, so have delayed
POPs/Clouds from exiting southeast of our area until mid to late
afternoon Tuesday. This trend will work to keep overnight lows
mild, settling in the mid 60s in the mountains to near 70 in the
Piedmont. Fog formation not out of the question, especially in
the higher elevations where precip may come to an end before
sunrise. High pressure settles over the region midday Tuesday,
allowing a clearing trend and drier conditions to take hold.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 300 PM EDT Monday...
Northern stream shortwave expected to shift the frontal boundary
south of our region Tuesday night, but deeper moisture and boundary
stall not far, where there could be showers lingering Tuesday
evening south of the VA/NC border. Return flow around the high
should bring a return of isolated threat of showers Wednesday
afternoon to the southern Blue Ridge and adjacent areas into
Southwest VA and the NC foothills.
Temperatures should stay close to normal Tuesday night, with lows in
the mid to upper 50s mountains, to lower to mid 60s east.
With high pressure nearby Wednesday and east flow, temperatures
should stay below normal, with highs ranging from the 70s mountains,
to lower 80s piedmont.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 300 PM EDT Monday...
Active pattern remains this period as broad mean trough stays
situated from the Great Lakes into the Gulf Coast states. A frontal
boundary stays south of us Wednesday night gradually dissipating
while next upstream front slowly edges into the Ohio Valley by
Saturday, reaching the central Appalachians by Monday. Model
consensus showing best chance of showers/storms to be more diurnal at
times, with greater increase in 24 hour chances as the front moves
late in the weekend into Monday. This far out will see how the
pattern sets up in terms of rainfall amounts and flooding threats.
Temperatures will stay near normal given cloud cover most of the
time, and higher moisture content in the atmosphere.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
As of 645 PM EDT Monday...
Bands/clusters of showers continue across the region this
evening with most deeper convection across far southern sections
mainly southwest of KDAN. However in between showers expect to
continue to see periods of sub-VFR in low clouds across the
mountains with overall VFR elsewhere outside of any heavier
downpours. Does appear that showers and storms may become more
widespread espcly over eastern/southern sections by midnight as
a cold front to the northwest sags in behind a departing wave
aloft. This may make for MVFR cigs/vsbys from KROA east into the
early morning hours with best coverage likely along the
KLYH/KDAN corridor where heavy rainfall will be possible. Thus
keeping in VCSH/VCTS mention at most sites while using a TEMPO
through this evening across the east for MVFR to IFR cigs/vsbys
within heavier downpours.
However still lower confidence on VSBYS/CIGS thanks to
the scattered nature of showers and storms across the region
after loss of heating. Cold front should begin to slowly move
through from northwest to southeast after midnight, resulting
in a wind shift from the northwest.
Expect lingering sub-VFR to persist over southern eastern
sections into Tuesday morning with showers around, and over the
mountains due to low clouds/fog early on. The frontal boundary
will continue south of the area Tuesday afternoon/evening
allowing for some drier weather and improvement in aviation
conditions. Appears most terminals should bounce back to VFR
cigs by early afternoon if not sooner pending how fast low vsbys
within fog increase. Any shra/tsra threat appears mainly south
and west of region so no mention of any convection later Tuesday
for now.
Extended Aviation Discussion...
The front to the south will remain to the south on Wednesday
before starting to return north Thursday. This will bring
showers and thunderstorms back to the forecast, especially at
the southern TAF locations mainly Thursday afternoon. As a
result MVFR ceilings and visibilities will likely return to
southern/western sections Thursday and perhaps across the region
Friday. Some improvement possible Saturday under weak high
pressure but still enough convective potential for localized
MVFR conditions Saturday afternoon. Late night/early morning
fog and low clouds also likely each night.
&&
.EQUIPMENT...
As of 200 PM EDT Friday Aug 4...
KFCX doppler radar will be down for the rest of the month due
to a failing bull gear. The radar will only be made operational
for brief periods if an imminent significant widespread severe
weather and/or hydrologic event occurs. Operating the system for
any amount of time until the bull gear is replaced risks a
catastrophic failure that would further extend system downtime.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...JM
NEAR TERM...JH/JM
SHORT TERM...WP
LONG TERM...WP
AVIATION...AMS/JH/JM
EQUIPMENT...WERT
Area Forecast Discussion
National Weather Service Las Vegas NV
847 PM PDT Mon Aug 7 2017
.SYNOPSIS...Much drier conditions are expected the next few days
with temperatures trending a few degrees above normal by Wednesday.
Any thunderstorm activity looks limited to the higher terrain of the
Sierra and southern Great Basin. A renewed push of monsoon moisture
will advance into northwest Arizona Friday into the weekend but
confidence remains low on how far west this moisture will make it.
&&
.UPDATE...Most shower and thunderstorm activity left over from the
afternoon across northern Mohave, Lincoln and Esmeralda Counties has
died off. The latest HRRR indicates a slight possibility of some
lingering showers in extreme northern portions of Esmeralda and
Lincoln Counties the rest of the evening into the overnight period.
Given the latest trends, I updated to remove mention of
showers/thunderstorms just about everywhere for the rest of tonight
except for those extreme northern areas.
&&
.AVIATION...For McCarran...Typical summertime diurnal wind pattern
expected through Tuesday. Generally, wind speeds should be less than
10 kts through the forecast period. Southwest winds overnight will
become light and variable will start by 13Z Tuesday morning trending
from north to east through the day with similar timing of
southwesterly winds tomorrow evening. Cloud bases will remain near
12 kft with a dry layer above 18-20 kft.
For the rest of southern Nevada, northwest Arizona and southeast
California...Typical summertime diurnal wind pattern exists for most
terminal today and tomorrow. Ceilings should be within VFR
conditions at all terminals above 10 kft through the forecast
period. &&
.PREV DISCUSSION...
156 PM PDT Mon Aug 7 2017
.DISCUSSION...
Through mid week, a less active monsoon is expected leading to drier
conditions and warmer temperatures. Today`s convection is brought to
you courtesy of daytime heating, lingering moisture and instability
enhanced by an upper low passing by to the north. Solid southwest
flow aloft will be in place to dry all but the far northern reaches
of the forecast area. Wednesday looks dry for the most part however,
shortwave energy impinging on the north central California coast
could help fire a storm or two over the Sierra. Monsoon moisture is
knocking on our eastern Mohave County door Wednesday afternoon but
the overall flow looks unfavorable no precipitation is expected
there. Thursday is questionable also but Mohave County is where the
action will be if anything fires. The monsoon is forecast to be more
active heading into the weekend with better available moisture and
greater instability. At this point, thunderstorms are possible from
about Vegas east Friday then expanding westward over the weekend.
The western portions of the forecast area are dry from Tuesday
through next weekend. Temperatures will be near normal over the next
seven days provided the deeper monsoon moisture stays east of the
area.
&&
.FIRE WEATHER...A drying trend will commence the next few days with
thunderstorm activity becoming limited to the higher terrain of the
southern Great Basin and Sierra slopes. Temperatures will be slowly
trending upwards each day through Wednesday with decreasing relative
humidity. Thunderstorm chances will return to northwest Arizona
Friday and into the weekend.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures. &&
$$
DISCUSSION...Salmen
Update/Aviation...Harrison
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