Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/24/18
Area Forecast Discussion
National Weather Service Wakefield VA
940 PM EDT Mon Jul 23 2018
.SYNOPSIS...
A moist southerly flow, coupled with a low pressure trough
aloft over the Tennessee Valley and southeast U.S., will result
in an unsettled pattern into Wednesday.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of 930 PM EDT Monday...
Latest analysis shows a stalled sfc boundary across the area
with a deep upr-level trough over the eastern CONUS. Not much
activity across the local area this evening with only sct
convection moving north at 40 mph. High res data showing
different scenarios for later tonight with respect to just where
the coverage comes from. HRRR shows higest pops along and east
of I95, while the RAP shows echoes incrg across the piedmont.
Takeaway is that pops have been increased to likely just about
everywhere after midnite. Not severe, but locally hvy downpours
and and lightning the main threats. Lows in the low-mid 70s.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
As of 330 PM EDT Monday...
Wet pattern continues into the short term period with upr-
level trough axis still west of the area Tue/Wed. PoPs in the
likely range through this timeframe. Although it won`t rain the
entire time, there will be periods of moderate to heavy rain
leading to some flood concerns. High temps in the upr 70s to
mid 80s both days. The trough finally deamplifies by Thu,
though a remnant sfc boundary will allow for continued changes
for rain especially over SE areas. High temps in the mid/upr
80s Thu.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 330 PM EDT Monday...
Models in fairly good agreement today that region stays east of the
mean upper trof axis over the Midwest, and remains in a relatively
moist SW flow aloft through the extended period. Extended period
begins with a shortwave having passed by the region on Thursday,
temporarily shutting off the stream of high PW air over the region.
Thus, Thursday night through Friday should have no worse than
scattered showers and tstms, with the greatest concentration of
activity across the SE third of the area. Frontal boundary tries to
move into the area from the west Friday night/Saturday, but stalls
over the area, as Atlantic ridge aloft prevails over the SE U.S. The
upstart is there will be chances for mainly diurnally driven
showers/tstms across the area through the weekend. The threat for
showers/tstms increases a bit on Day 7 as shortwave trof approaches
the region from the OH/TN Vlys, enhancing the rain chances.
Temperature-wise, near normal temperatures are anticipated through
the period, with max temps in the 80s to around 90, and min temps in
the upper 60s to mid 70s, highest southeast portions of the
area.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
As of 730 PM EDT Monday...
Widely scattered showers continue over the region but have
diminished over the past couple of hours. Sct/bkn MVFR clouds
prevail over the TAF sites but more persistent MVFR and IFR
conditions will develop during the overnight and Tue as rain
chances increase. Mostly SE winds tonight 10-15 kt with gust up
to 20-25 kt along the coast.
Unsettled weather continues into Wed. Expect VFR or MVFR conditions
at all sites with some isolated IFR conditions possible in heavier
showers/tstms. Some improvement expected late in the week.
&&
.MARINE...
As of 730 PM EDT Monday...
Little change in overall marine weather conditions expected through
Wednesday, as upper low remains SW of the region and an enhanced
southerly gradient continues over the area. Plan on extending
current SCAs through at least 8 am Wednesday, with the afternoon
forecast. Winds on the Bay are expected to continue in the 15 to 20
knot range through Wednesday, and around 20 kts sustained on the
ocean. Seas on the ocean will remain AOA 5 feet, with 3 to 4 foot
waves on the Bay.
Some slow improvement expected Wednesday night into Thursday, as
upper low weakens, and moves NEWD to the north of the area. This
will cause winds to veer to the SW, which will allow drier area to
move in, and gradient to decrease.
Anticipate high rip current risk continuing Tuesday on area beaches.
Significant seas and long-shore currents should persist, and enhance
the rip current risk, through Tuesday.ishing to 10-15kt.
&&
.TIDES/COASTAL FLOODING...
As of 1045 AM EDT Monday...
The persistent SE flow combined with the large waves near the mouth
of the Chesapeake Bay is starting to allow water to back up in the
bay, especially across the northern bay. As such, anomalies are 1.5
ft to 1.8 ft above astronomical tide. Given the recent uptick in
anomalies at Lewisetta, have also issued an advisory for the
northern Neck along the Potomac. See no reason why anomalies will
decrease much tomorrow into tomorrow night either, so another round
of coastal flood advisories will be likely again for Tuesday night`s
high tide cycle.
A high risk of rip currents if forecast today for all beaches along
with the potential for dangerous shorebreak. More than likely, there
will be a moderate or high risk of rip currents along the beaches
for much of the week due to the persistent SE flow.
&&
.EQUIPMENT...
As of 320 PM EDT Saturday...
KDOX radar is inoperable due to a failure of the motor. All
parts will not arrive until Tuesday July 24. Return to service
is unknown at this time.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...Coastal Flood Advisory until 4 AM EDT Tuesday for MDZ021>023.
NC...Flash Flood Watch through Tuesday evening for NCZ012>017-
030>032-102.
VA...Flash Flood Watch through Tuesday evening for VAZ048-060>062-
064>069-075>090-092-093-095>098-509>525.
Coastal Flood Advisory until 4 AM EDT Tuesday for VAZ075-077.
MARINE...Small Craft Advisory until 8 AM EDT Wednesday for ANZ630>632-
634-650-652-654-656-658.
Small Craft Advisory until 1 PM EDT Tuesday for ANZ635-636-638.
Small Craft Advisory until 7 AM EDT Tuesday for ANZ633.
&&
$$
SYNOPSIS...MAS
NEAR TERM...MAS/MPR
SHORT TERM...MAS
LONG TERM...WRS
AVIATION...MAS/JEF
MARINE...MRD
TIDES/COASTAL FLOODING...
EQUIPMENT...
Area Forecast Discussion
National Weather Service Albany NY
849 PM EDT Mon Jul 23 2018
.SYNOPSIS...
A tropical air mass will remain over eastern New York and
western New England tonight through Wednesday, as a cold front
remains well west of the region with high pressure continuing to
be over the north Atlantic ridging westward into New England.
Weak disturbances in the moist southerly flow will bring
isolated to scattered showers and thunderstorms tonight into
Tuesday night. By Wednesday, the front will move eastward with
numerous showers and scattered thunderstorms with very heavy
rainfall across the area. The threat for heavy rainfall
diminishes Thursday morning with humidity levels beginning to
lower.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Flash Flood Watch now in effect until Wednesday evening for the
eastern Catskills, Helderbergs, and Schoharie Valley...
Areal coverage of showers has decreased with loss of daytime
heating however threat will continue with persistent southerly
flow of deep tropical moisture into the region. Orographic will
enhanced showers overnight. Area of concern will be the eastern
Catskills where have the flash flood watch. A portion of the
watch area received 3 to 6 inches of rainfall already; refer to
the latest public information statement for reports. This area
needs to be closely watched were the additional rainfall occurs
and the intensity of the rainfall. Overall the coverage is
expected to decrease overnight. Very muggy and warm with lows
only falling into upper 60s to lower 70s.
As of 551 pm EDT...A Flash Flood Watch has been extended into
Wednesday evening for the eastern Catskills and Helderbergs with
Schoharie CTY added into it with portions of these areas
getting 2-6 inches of rainfall. The short-wand additional
rainfall will occur. If storms remain light and have that
focused the heavy rain in the south to southeast flow moved
north of the region, but additional showers and thunderstorms
have popped up in the moist southerly flow where PWATS are 1 to
3 STD DEVS above normal. The PWATS are generally 1.7-2.0+ inches
which are nearly 200 percent of normal.
We have had locally heavy downpours with hourly rainfall rates
of 1-2"/hr. The SBCAPEs per the latest RAP are 500-1500 J/Kg
with 0-6 km shear values of 20-25 kts. Training of the showers
we will continue to monitor with the dominate "Tall and Skinny"
sounding profiles. We continue to issues FLS`s for the rest of
the late afternoon into the early evening time period, as the
front remains west of the region associated with the the cutoff
low over the OH/TN Valley which looks like it will open up
briefly with a full latitude H500 trough over the eastern CONUS.
The subtropical high continues to ridge westward from the
northern Atlantic with the tropical moisture rich axis pushing
westward. Some retooling of the POPS will be done with this
brief update.
The latest CAMS show the showers becoming isolated and
diminishing overnight due to the loss of the daytime heating
with very humid conditions with lows in the mid 60s to lower
70s. The high min record for Albany for July 24th is 74F in 1935
and we may tie it. Patchy fog may also occur at many locations.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
As of 455 pm EDT...
Tomorrow...The trend from the latest NAM/GFS/ECMWF/CMC and many
ensembles members is for the strong closed H500 ridge over the
North Atlantic (north of Bermuda) to build westward (from west
to east) with mid and upper level heights increasing over much
of the forecast area. The upstream upper trough become neutral
to negatively tilted with the embedded H500 circulation trying
to re-close off over the TN Valley. An atmospheric river of
tropical moisture looks like it will be west of most of the
forecast area, but locations west of the Hudson River Valley may
get grazed by scattered to numerous showers and thunderstorms
with more of a southerly flow of moisture in the low to mid
levels of the atmosphere. The latest 12Z GEFS show the PWAT
anomalies being greatest over western and central NY grazing the
western Mohawk Valley, eastern Catskills, and western Dacks.
Our greatest concern remains the eastern Catskills/Schoharie CTY
corridor where the "pump has been primed". SBCAPES will likely
get into the 500-1500 J/kg range. PWATS may lower under 1.50
inches east of the Hudson River Valley with some slightly drier
air coming in from the east. Sfc dewpts will still be in the
60s to lower 70s. We will have to monitor for training elements
of showers/isold to sct thunderstorms especially west of the
Hudson River Valley. We kept isold-sct showers and t-storms
east, especially timed to the diurnal heating. Highs will be in
the mid and upper 70s over the higher terrain, and upper 70s to
mid 80s over the valleys. A few upper 80s are possible over the
Capital Region/mid Hudson valley.
Tue night...initially the showers and isold-scattered
thunderstorms should shrivel up with the loss of the daytime
heating in the tropical air mass. However, well after midnight
low and mid level heights begin to fall and progress eastward
as we start to increase the POPS over the western periphery of
the forecast area for numerous showers and a chance of
thunderstorms. PWATS surge back to +2 to +3 STD DEVS above
normal with an anomalous H925 +u component /southerlies/ of the
wind of +2 to +4 STD Devs above normal. Muggy conditions persist
with lows in the upper 60s to lower/mid 70s.
Wed-Wed Night...We may need a Flash Flood Watch expanded across
most of the forecast area, as an atmospheric river of tropical
moisture moves into region from west to east. PWATS are at or
about 2.00 inches with tall and skinny sounding profiles. We
are uncertain on the amount of heating that will occur, but
better chances possibly from the Hudson River Valley east for
thunderstorms. WPC continues to have most of the HSA in a
SLIGHT-MODERATE Risk of exceeding the Flash Flood Guidance 8 am
WED to 8 am THU. Rainfall rates could exceed 2 inches an hour.
The low-level convergence increases with the frontal axis moving
across the region WED pm into the evening period on the
NAM/GFS/EC. Training showers and thunderstorms may be a big
problem. Some locations could receive 2-5" of rainfall,
especially west of the Hudson River Valley on the NAM. A wave
may move along the boundary WED night keeping the rainfall going most
of the evening. We keep POPS in the likely to high chc range
after midnight. Highs will be in the 70s to lower 80s on WED,
with lows in the 60s to lower 70s. Please see our Hydro
Discussion for more details on the HYDRO situation, especially
the threat of flash flooding.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 455 pm EDT...The active pattern continues into the
extended period as a broad upper level trough over southern
Canada/Great Lakes and strong high pressure in the western
Atlantic allows southwesterly flow to prevail over the Eastern
CONUS. Humidity levels remain rather high as a result and we
will be monitoring multiple boundaries which will keep chances
for rain and storms in the forecast, although some days will
have higher threats than others.
A shortwave trough embedded in the large wave trough over southern
Canada will be pushing through NY/western New England on Thursday.
With the global guidance showing the trough already through central
NY by 12z Thursday, we placed likely POPs in the Taconics and
western New England where the best cyclonic vorticity advection
should be and decreased POPs to low end chance POPs in the
Adirondacks and western Mohawk Valley. Precipitable water values
remain high between 1.50 - 2.00" ahead of the trough with warm
clouds depths still ranging 10-12kft. This means the threat for
heavy downpours continues and areas that are hard hit with rain on
Wednesday will likely have a lower tolerance for any additional rain
before flooding takes place.
The trough should should exit into VT and northern New England by
00z Friday with upper level winds shift northwest in its wake.
Although this looks to give way to mid-level drying, surface dew
points will likely remain in the 60s giving us yet another muggy
night Thursday night. One good thing is some subsidence in its wake
should allow breaks in the clouds.
The broad long wave trough over southern Canada progresses eastward
on Friday with 500 heights gradually falling through the daytime. At
the surface, there will also be a cold front heading eastward that
we will have to closely monitor. Breaks in the clouds from the
overnight should continue into the daytime ahead of the front which
means some daytime heating should increase instability values.
Current guidance shows values rising to 1000-1500J/kg by 18z Thurs -
00z Fri. 0-6km shear values will also be decent thanks to the
approaching trough, ranging 35-40kts. The previously mentioned mid-
level drying should also steepen mid-level lapse rates to 5.5-6C/km.
All of these signatures suggest that the approaching front could
lead to a line of showers and thunderstorms with some strong to
severe thunderstorms possible. Damaging winds likely main threat.
The front exit into eastern New England by 12z Saturday with broad
cyclonic flow continuing in its wake as the large scale trough moves
into the Northeast. A secondary boundary associated with the trough
axis should move through eastern NY/western New England by 18z Sat -
00z Sunday which should finally lead to a noticeable drop in humidity
levels. While mid-level moisture is lackluster, the cyclonic flow
and trough axis could lead to some scattered afternoon
showers/storms so continue low end chance/slight chance POPs for
Saturday. High temperatures should be lower than in previous days
thanks to the cyclonic flow, only reaching the upper 70s to low 80s.
Sunday likely will be the driest day of the extended period as high
pressure noses in from the Ohio Valley and upper level ridging
strengths. Upstream, however, yet another trough deepens over the
midwest and most of the global guidances shows it cutting off up to
500mb. This suggest that high pressure in the Northeast should
strength heading into Monday but this system should eventually push
into Northeast by midweek as isentropic lift increases. Still
uncertain on exact timing of this next potential widespread rain
event but increases POPs to chance for Monday night and Tuesday to
reflect the potential.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Areal coverage of showers has decreased with loss of daytime
heating however threat will continue with persistent southerly
flow of deep tropical moisture into the region. Orographic will
enhanced showers overnight. Have addressed threat with VCSH in
TAFs as can not time individuals storms. Overall widespread MVFR
conditions/ceilings are expected to develop this evening then
persist through the overnight hours and Tuesday morning with an
improve to VFR expected by early afternoon. IFR is possible at
KPSF overnight and have indicate this with scattered clouds
under 1000 feet. Showers are not expected to be as widespread
Tuesday, have VCSH in TAFs with daytime heating.
Southeast to south flow continues through TAF period; 00Z/Wednesday.
Gusts are expected to persist at KPSf this evening with gusts
picking up Tuesday across area with gusts into the teens to
around 20 knots on Tuesday.
Outlook...
Tuesday Night: Moderate Operational Impact. Chance of SHRA.
Wednesday: High Operational Impact. Definite SHRA...TSRA.
Wednesday Night: High Operational Impact. Definite SHRA...TSRA.
Thursday: Moderate Operational Impact. Chance of SHRA...TSRA.
Thursday Night: Low Operational Impact. Slight Chance of SHRA.
Friday: Moderate Operational Impact. Chance of SHRA...TSRA.
Friday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Saturday: Moderate Operational Impact. Scattered SHRA...TSRA.
&&
.FIRE WEATHER...
A tropical air mass will remain over eastern New York
and western New England tonight through Wednesday, as a cold front
remains well west of the region with high pressure continuing to be
over the north Atlantic ridging westward into New England. Weak
disturbances in the moist southerly flow will bring isolated to
scattered showers and thunderstorms tonight into Tuesday night. By
Wednesday, the front will move eastward with numerous showers and
scattered thunderstorms with very heavy rainfall across the area.
The threat for heavy rainfall diminishes Thursday morning with
humidity levels beginning to lower.
The RH values will increase to 90 to 100 percent late tonight,
and Wednesday morning. They will only lower in the humid air
mass to 60 to 80 percent Tuesday afternoon.
The south to southeast winds will diminish to 5 to 15 mph
tonight, and increase to 10 to 20 mph on Tuesday. The winds will
be southerly at 5 to 15 mph Tuesday night.
Locally heavy rainfall is possible tonight into the mid week,
with the most widespread rainfall expected Wednesday and
Wednesday night.
&&
.HYDROLOGY...
Unsettled weather impacts the Hydro Service Area /HSA/ through
most of the week.
A Flash Flood Watch is in effect from tonight through Wednesday
evening /midnight/ for the eastern Catskills, Helderbergs and
Schoharie Valley. 2 to 6 inches of rainfall fell in the Watch
area this morning into the afternoon. The highest totals were
across extreme southeast Schoharie Co into western Albany,Greene
and Ulster Co. Prattsville reached the Alert Stage with the
heavy rainfall that occurred. Another area of heavy rainfall
occurred across the central and eastern Mohawk Valley with 1 to
4 inches of rainfall.
A slow moving cold front approaching from the west, along with
several weak disturbances moving northward within a very moist
airmass in place, will lead to scattered showers and isolated
to scattered thunderstorms, some with locally heavy downpours
for tonight into Tuesday. Rainfall amounts will greatly vary
from a tenth to a half an inch in some spots with localized one
to two inch amounts or greater amounts especially, south and
west Capital Region, and near the eastern Catskills.
The front may stay far enough west due to high pressure
building in from the western Atlantic Ocean for the better
coverage of showers and thunderstorms being west of the Hudson
River Valley tomorrow into tomorrow night. Some of these
locations like the western Adirondacks and western Mohawk
Valley received little rainfall today. The pump has been primed
across the eastern Catskills, so that is why we continued the
Flash Flood Watch now through the mid week.
A potential will exist for training showers/thunderstorms that
would result poor drainage flooding or an isolated flash flood
if heavy rainfall repeatedly occurs over the same areas of the
HSA tonight to Thursday morning time fame, with the best
potential Wednesday into Wednesday night as the frontal boundary
slowly approaches from the west and moves across the region.
The ALY HSA river and stream levels are mainly below normal and
our recent dry conditions are noted in the latest drought
monitor with D0-D1 levels. However, intense rainfall rates of
1-2 inches an hour and repeated locations getting large amounts
of rainfall over the next 2 or 3 days will need to be
monitored.
The Flash Flood Watch will likely need to be expanded across
more of the ALY HSA for late Tuesday night or Wednesday morning
into Thursday morning depending on the where the heavy rain
occurs the next 24 hours or so, and the HI RES NWP trends.
A drier air mass will likely build in toward the weekend.
For details on specific area rivers and lakes, including observed
and forecast river stages and lake elevations, please visit the
Advanced Hydrologic Prediction Service /AHPS/ graphs on our
website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Flash Flood Watch through Wednesday evening for NYZ047-051-058-
063.
MA...None.
VT...None.
&&
$$
SYNOPSIS...KL/Wasula
NEAR TERM...IAA/Wasula
SHORT TERM...Wasula
LONG TERM...Speciale
AVIATION...IAA
FIRE WEATHER...KL/Wasula
HYDROLOGY...KL/Wasula
Area Forecast Discussion
National Weather Service Bismarck ND
942 PM CDT Mon Jul 23 2018
.UPDATE...
Issued at 935 PM CDT Mon Jul 23 2018
No significant changes for the late evening update. We did bump up
clouds in the southwest and south central overnight. Mesoscale
models are still hinting at some weak convection late tonight
associated with a warm front lifting northward into the southwest
and south central. Can`t completely rule it out but thinking that
this have minimal impacts with mainly trace amounts given the
high bases (around 10kft) and dry lower atmosphere.
UPDATE Issued at 628 PM CDT Mon Jul 23 2018
Populated sensible weather elements and blended to mid evening
values. Otherwise no changes to the early evening forecast. Even
though some of the mesoscale models indicate weak convection
developing late evening and overnight over the southwest and south
central, will continue with the dry forecast for now and monitor
through the evening.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 350 PM CDT Mon Jul 23 2018
A Marginal Risk for severe thunderstorms Tuesday highlights the
short term forecast.
A quiet and dry afternoon will continue across western and central
North Dakota with surface high pressure. For late tonight, the CAM
suite through the 18 UTC HRRR all depict the potential for
isolated weak elevated convection across the far southwest and
south central in a zone of weak warm air advection associated with
a warm front. This development is somewhat uncertain, and went
with a dry forecast for now.
For Tuesday afternoon and evening, outside of the far west, most
of the area is highlighted by a Marginal Risk for severe
thunderstorms in the SPC Day 2 Convective Outlook. Overall, the
deep layer shear is forecast to be strong around 50 kts, however,
overall moisture and instability are modest around 500-1000 j/kg.
Thus, high based storms with large inverted-v soundings would be
favored. Convection may first initiate across the north with the
arrival of a series of impulses in northwest flow aloft in the
early afternoon. A somewhat relative increase in intensity and
coverage is possible further south and a bit later in the
afternoon with enhanced convergence along the warm front and weak
surface low between ND Highway 200 and I-94. Deep layer shear is
oriented fairly parallel to this front, which would favor the
potential for a couple organized linear bowing segments with cold
pool generation when considering the large inverted-v soundings.
Given the high shear/low CAPE high based storms, damaging winds
would be a primary threat followed by large hail to around half
dollar size.
.LONG TERM...(Tuesday night through Monday)
Issued at 350 PM CDT Mon Jul 23 2018
Cool and rather quiet weather highlights the extended forecast.
The 12 UTC global suite depicts northwest flow aloft across the
Northern Plains through the extended forecast. This would favor
below normal temperatures generally in the 70s, with sporadic rain
shower and thunderstorm chances with impulses embedded in the fast
flow.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 935 PM CDT Mon Jul 23 2018
VFR conditions are expected through the 00Z forecast period.
Northwest flow early this evening becoming light and variable. On
Tuesday, surface flow becomes south to southeast at KDIK and KBIS
while remaining northerly at KISN, KMOT and KJMS. Only scattered
to broken mid level clouds down to around 8-10kft, especially
north through the 00Z period. Isolated shower/tstm activity is
possible, mainly south of KDIK and KBIS late tonight, then from
KISN to KMOT Tuesday afternoon. Nothing widespread enough at this
time to mention in any individual TAF.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TWH
SHORT TERM...PA
LONG TERM...PA
AVIATION...TWH
Area Forecast Discussion
National Weather Service Buffalo NY
1042 PM EDT Mon Jul 23 2018
.SYNOPSIS...
Our region will remain situated between weakening low pressure over
the Ohio Valley and strong high pressure off the Atlantic coastline
through Wednesday. This will result in a persistent southerly flow
of warm and very humid air across our region...which in turn will
promote increasingly unsettled conditions as we push through the
first half of the week. After that...a cold front will then cross
our region on Thursday and usher in a return to cooler and drier
weather for Friday and next weekend.
&&
.NEAR TERM /THROUGH TUESDAY/...
Warm and humid conditions will continue across the eastern Great
Lakes overnight and into tomorrow as the region remains between an
upper level trough that stretches from the Upper Great Lakes to
Florida and a strong upper level ridge over the northern Atlantic
Ocean. Southerly flow along the US East Coast is providing for a
constant feed of tropical moisture with PWAT values of 1.5 to 2.2
inches per SPC mesoanalysis. Surface dew points range from the upper
60s across the western Southern Tier of NY to the low 70s in North-
Central NY.
Regional radar late this evening shows an elongated region of broken
bands of showers oriented south to north stretching from near
Baltimore Maryland across western and central New York and across
Lake Ontario. These showers are shifting through this moist flow on
the east side of the deep trough to our west. The moist southernly
flow will continue to help track scattered to numerous showers with
perhaps some isolated embedded storms south to north through the
overnight. Have blended some guidance from the HRRR into the
forecast grids as the model seemed to be initialized well with
recent radar. Heavy downpours will remain a threat with any of the
showers due to the deeply saturated atmosphere in place. Temps will
remain very mild with steady southerly flow and plentiful cloud
cover. Lows only expected to reach the upper 60s well inland to low
70s near the lakeshores.
The upper level trough remains nearly stationary into Tuesday with
an nearly unchanged set-up from what we saw on Monday. Diurnally-
enhanced showers and thunderstorms are expected again as some mid-
level vorticity will pass across north across the forecast area
Tuesday afternoon. This will result in more widespread shower
activity mainly from I-390 eastward. Basing average rainfall will
range from 0.1-0.25 across far Western NY to 0.25-0.50 inch east of
Lake Ontario. One thing to note, the orientation of the south to
north bands of showers and thunderstorms will continue a heavy rain
threat Tuesday afternoon east of Rochester as training showers and
storms may move over the same location for a prolonged period of
time. At this time, the main threat is across eastern NYS however we
will need to monitor this threat especially into Tuesday night.
Rainfall rates of 1-2 in/hr are possible in any thunderstorms.
Similar warmth expected Tuesday with temperatures ranging from the
low 80s across the higher elevations to the upper 80s elsewhere.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH FRIDAY/...
...Heavy rain intervals possible during this period...
Nearly uni-directional flow throughout the column from south to
north will favor the continued northward advancement of deep
moisture into the region through mid-week. This is characterized by
multi-model PWAT values near or in excess of 2 inches for an
unusually long duration that extends through the short term period.
With that in mind, the atmosphere will be primed to rain quite
efficiently with little necessity for substantial dynamical forcing
for ascent. Unfortunately for us, there will be additional forcing
crossing the area that will make a decent part of the short term
period cloudy and tropical feeling.
Timing for rainfall will revolve around a couple of passing waves in
the the upper level flow. The best estimates for the passage of
these will be Tuesday evening and again Wednesday afternoon/evening.
Keep in mind, these are just the impulses the models have the
resolution to capture, and additional mesoscale forcing is likely.
However, PoPs were constructed to focus the best rain chances during
these two intervals.
With each interval, right entrance region divergence is coupled with
low level convergence first in the form of a low level jet nose and
second in the passage of a weak surface wave. This should provide
good forcing for ascent, which when coupled with modest CAPE values
and deep warm cloud layer depths in the CAPE profile, allowing for
efficient low centroid thunderstorm development. As a result, the
heavy rainfall mention in the forecast was maintained as were
categorical PoPs. QPF values will likely vary wildly where
thunderstorm training develops given the uni-directional flow
profile, however a general 1-3" of averaged areawide rainfall
during the period seems reasonable at this juncture. While most
locations should be able to manage 1-3" of rainfall spread over
this duration, should training develop, some flooding will be
possible. Additional guidance will need to be examined in the
future to ascertain whether this threat necessitates a flash
flood watch. At this time, it does not.
With the passage of the surface boundary on Wednesday night, drier
air rapidly (if temporarily) advances into the region from the west.
This will end the threat of heavy rainfall abruptly as a rapidly
drying column aloft and shunting of deep moisture to the east couple
to eradicate the high PWATs that will have become semi-resident.
This dry period may be short-lived, however, as a deep upper trough
will be advancing into the western and central Great Lakes by that
juncture, indicating rapidly cooling air aloft.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
An area of low pressure near James Bay along with an upper low will
shift northeast into Central Quebec and continue northeast through
Saturday night. The trough axis will cross the region on Saturday
and will provide a slight chance for some showers across the area
through the Saturday overnight time period.
An area of high pressure will push through for Sunday and as a
result we should see mostly dry conditions. For Monday, guidance is
coming into some better agreement that a weak surface low will trek
from the Ohio Valley through western New York and into the North
Country. The Euro is a little slower with the system having it cross
the area late Monday, while the GFS brings it into WNY starting
Monday morning. PWATs up to and above 1.50 inches are possible
during this time as well.
Highs during this period will generally be in the mid 70s to near
80, except for Monday when max temps may not warm above the low to
mid 70s for most of the area due to cloud cover and showers
affecting most of the area. Low temperatures during this period will
be in the mid 50s to around 60, and warming slightly for Monday
night to the upper 50s and mid 60s.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Broken bands of south to north oriented showers will continue to be
a threat to the terminals into the overnight as we remain within a
deeply saturated atmosphere on the eastern side of an elongated
upper-level trough west of New York. The humid airmass will result
in lower VFR cigs with sub-VFR mainly exhibited within and around
heavy showers and any isolated storms. Cloud cover and southwest
winds around 10kts will limit the possibility of fog tonight.
Showers and thunderstorms will continue to be possible again Tuesday
as we remain in the moist environment. Coverage will be greater
especially from KROC and east. Flight restrictions are possible
however timing and placement is still in question. Further west,
across KIAG, KBUF and KJHW, showers and thunderstorms will be less
of a threat.
Outlook...
Wednesday...VFR/MVFR in showers and thunderstorms.
Thursday and Friday...Mainly VFR with scattered showers.
Saturday...Mainly VFR with a slight chance of showers.
&&
.MARINE...
A prolonged period of unsettled weather is expected for most of
this week...as a warm and humid airmass will support frequent
opportunities for scattered to numerous showers and
thunderstorms...along with attendant locally higher winds and waves.
Outside of these...winds and waves will generally remain below Small
Craft Advisory levels.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.
&&
$$
SYNOPSIS...JJR
NEAR TERM...HSK/Smith
SHORT TERM...Fries
LONG TERM...SW
AVIATION...HSK/Smith
MARINE...HSK/JJR
Area Forecast Discussion
National Weather Service Cheyenne WY
518 PM MDT Mon Jul 23 2018
.UPDATE...
Issued at 513 PM MDT Mon Jul 23 2018
Please see latest 00z Aviation Discussion
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 330 PM MDT Mon Jul 23 2018
Short term issues deal with chances for severe thunderstorms this
evening.
Currently...Stationary surface front across southeast Colorado up
into Albany County near Laramie and then north into the Casper
area. Southeast upslope flow has kept low level moisture in the
area east of the Laramie Range with broken stratocu over Cheyenne
. Latest SPC mesoanalysis showing a fairly uncapped environment
with maybe the exception around Cheyenne with the low cloud deck.
20Z surface based CAPE of 2000 to 3000 J/KG with bulk shear around
45kts. Marginal Risk area still looking good from SPC this
afternoon.
Latest HRRR simulated radar showing potential for severe
thunderstorm development across southern Albany County spreading
east into Laramie County and Cheyenne after 23Z. Also showing
possibility of discreet supercell development near Wheatland and
up by Douglas this afternoon. Latest radar showing pretty good
verification with cells developing near Shirley Basin and just
south of Douglas. So confidence is pretty good on the HRRR
solution for this afternoon.
A drier day Tuesday as guidance showing most of the PoPs/QPF
south in Colorado as the Four corners high is suppressed by low
tracking across northern Montana and southern Canada.
.LONG TERM...(Tuesday night through Monday)
Issued at 330 PM MDT Mon Jul 23 2018
A pretty wet pattern ahead for the CWFA as monsoonal moisture
continues to move into the area. This monsoonal moisture is
forecast to interact with a surface boundary dropping into the
area from the north Wednesday afternoon. All guidance showing
fairly widespread precip late Wednesday afternoon into Wednesday
evening. This front is not expected to move much through Sunday,
only drifting slightly east into the Panhandle Friday, then
shifting back west Saturday as an upper level shortwave rides
along the front.
Four corners high shifts west Monday next week that may cut off
monsoonal flow over the area. This will likely bring dry weather
back to the area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 513 PM MDT Mon Jul 23 2018
Latest radar shows a couple scattered thunderstorms across the
Albany County with one moving SE towards KLAR in the early period
of this TAF set. Overall trend is for scattered storms across the
area with possible showers across the NE Panhandle in the next few
hours. Looking at a similar setup to MVFR conditions forming again
post-storms across KCYS. There is some model guidance differences
on how low ceilings get during the 06z to 12z range that will
require further evaluation for next TAF set. VFR conditions will
persist across the remaining sites post-convection.
&&
.FIRE WEATHER...
Issued at 330 PM MDT Mon Jul 23 2018
Minimal fire weather concerns with monsoonal moisture over area
through Sunday. Fairly widespread wetting rains expected each
afternoon and early evening. Afternoon humidity expected to stay
well above critical levels with good to excellent overnight
recoveries. No weather related fire weather concerns at least
until next week.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
UPDATE...WM
SHORT TERM...GCC
LONG TERM...GCC
AVIATION...WM
FIRE WEATHER...GCC
Area Forecast Discussion
National Weather Service Dodge City KS
1100 PM CDT Mon Jul 23 2018
...Updated Aviation...
.SHORT TERM...(This evening through Tuesday)
Issued at 301 PM CDT Mon Jul 23 2018
Isolated showers and thunderstorms were forming across parts of
west central Kansas this afternoon from south of Goodland to near
Scott City, in a favorable area of low level moisture and
instability. The HRRR has been focusing some isolated development
in this area for the past several runs. Deep layer shear is pretty
weak in this area so am not expecting any organization from these
storms through the late afternoon which is also what the HRRR has
been showing. Better instability and shear has been farther west
into the Front Range of Colorado. The models show this to be the
main area of afternoon thunderstorm development. Of interest here
is that the HRRR has been trending toward the idea of
thunderstorms moving off the southern Front Range and forming into
a convective segment that dives southeast toward the OK/TX
Panhandles and possibly clipping far southwest Kansas later this
evening. As a result, will shift the highest chance pops into
that area tonight. There could be some lingering isolated to
widely scattered showers and thunderstorms lingering through the
remainder of tonight over southwest Kansas so will maintain at
least some low chance pops through Tuesday morning before
precipitation gradually diminishes.
Cloud cover will linger through much of the night, so will keep
overnight lows at or a few degrees above the warmer MAV guidance.
Tuesday should be similar to or slightly warmer than today,
temperature-wise.
.LONG TERM...(Tuesday night through Monday)
Issued at 301 PM CDT Mon Jul 23 2018
Tuesday night should be fairly quiet as any lingering daytime
showers will diminish quickly. Through the remainder of this week,
strong upper level high pressure, currently centered over New
Mexico, will slowly retrograde westward to over southern California
by Thursday night. As it does, stronger northwesterly flow around
the northeast quadrant of the upper high will slowly move south
toward the central Plains. This will bring increasing chances for
precipitation to western Kansas late in the week as thunderstorms
developing along the front range of northern Colorado and Wyoming
become organized into convective complexes that move out over
central and western Kansas mainly during the overnight hours. All
of the global models (GEM/GFS/ECMWF) are showing this although
timing and heavy precipitation tracks vary with the models.
Suffice it to say, likely chances for thunderstorms seem
reasonable later in the week, along with the potential for some
locally heavy rain and flash flooding. Temperatures should stay on
the cool side of normal through this period as well.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1100 PM CDT Mon Jul 23 2018
A quiet TAF forecast cycle with no convective concerns, VFR and
light winds. Thunderstorm complex over eastern Colorado at 04z
will move south overnight and remain mostly out of SW KS. NAM
suggests outflow and a few residual showers may approach LBL/GCK
for a few hours toward sunrise, but that would be it. With
uncertainty, kept out of the TAFs. Cirrus anvil over the
terminals currently will slowly dissipate through early Tuesday
morning, followed by another cumulus field Tuesday afternoon. No
thunderstorms are expected Tuesday afternoon through Tuesday
night, with forcing and instability lacking. Expect convection to
return Wednesday night through Thursday morning. Light winds will
continue Tuesday, trending SEly at less than 10 kts by 00z Wed.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 68 88 68 95 / 20 20 10 10
GCK 66 86 67 94 / 30 30 10 10
EHA 66 87 67 95 / 50 20 10 10
LBL 68 89 68 95 / 30 20 10 10
HYS 65 89 66 92 / 10 10 0 20
P28 70 91 68 95 / 0 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Gerard
LONG TERM...Gerard
AVIATION...Turner
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1034 PM EDT Mon Jul 23 2018
.SYNOPSIS...
A broad upper low will settle across the Deep South through
Wednesday. This low will remain nearly stationary and support moist
unsettled weather across the region through mid-week, before
weakening ahead of an approaching cold front.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 1020 PM: An upper low is centered over the southwestern
Appalachian region. This feature maintains a southeasterly upslope
flow into the CWFA from the Atlantic. After a very active afternoon,
most of the area is now free of precipitation, with only a few
light showers lingering. Consensus of new 00z HiRes Windows and
latest HRRR is that activity will be sparse over the next couple
of hours, though with the sfc/upper pattern not having changed
much from the day and 850mb flow picking up nocturnally, isolated
to scattered showers could redevelop especially along the Blue
Ridge. Revised PoPs reflect this trend. PWAT values are rather
high, in the vicinity of 1.7 inches per 00z soundings at GSO
and FFC. Intense rainfall still could occur on an isolated basis
tonight. Thus we will retain the Flash Flood Watch even with PoPs
being lowered across the watch area.
Numerous to potentially widespread convective coverage develops
again Tuesday. There are some questions whether conditions will be
favorable for Watch level flash flooding events during the day; mid
shift will have the opportunity to extend the watch if needed, but
right now newest guidance does not justify an extension. Certainly
isolated heavy rainfall will be possible. Severe chances should
be less, but again, can`t be completely ruled out.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 220 PM EDT Monday: The short-term fcst picks up at 00z on
Wednesday with a persistent upper trof centered over the Southeast
CONUS and steep upper ridging to the east and west of the trof.
Over the next couple of days, heights will gradually rise as the
trof deamplifies and lifts northward. By the end of the period
late Thurs, another broad upper trof will dig down across the Great
Lakes while ridging maintains itself to the east and west. A large
sfc low will be co-located with the upper low over the Southeast
to start the period. On Wed, the sfc low begins to lift northward
as a cold front approaches the fcst area from the NW. The front is
slow to push thru the CWFA, but by Thurs afternoon most of the
guidance has it just SE of the CWFA. In its wake, high pressure
will spread over the area to end the period. As for the sensible
wx, moist SELY low-lvl flow will be in place early Wed. As the day
wears on, and the cold front will gradually push into the CWFA
and the axis of SLY winds will shift farther east. By Thursday
morning, winds will have become light and vrb over most of the
fcst area and NWLY over the higher terrain. In addition, much
of the deeper moisture will have moved south and east of the CWFA.
This should make for a drier Thurs with less cloud cover by the
afternoon. The main threat for the period is still isolated
flooding on Wed with a greater overall threat across the eastern
half of the CWFA. High temperatures will start out about a category
below normal on Wed and warm to near normal for Thursday as cloud
cover dissipates.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 155 pm Monday: The upper pattern maintains a trough over our
region. Starting Thursday evening with a weak cold front crossing
our area from the NW. Models show moves slowly across the Midlands
to the coastal plain on Friday and Friday night with drier air
filtering into the region. The higher Precipitable Water values
will be temporarily suppressed to the coast and Florida to start the
weekend. However, P Wats of around 2 inches for the foothills and
piedmont are forecast to return by Sunday night and remain to start
the week. By Sunday, the winds will shift to a more southerly
direction beginning another wet period in our forecast. On the 500mb
map, the next big trough will cross the upper Plains Saturday night
with the trough axis reaching the Mississippi River by early Monday.
Moist flow out of the Gulf will become well established Monday and
Monday night. CAPE values will be rather low through the medium
range but rising to around 2000 from Elberton to Chester late
Monday. High temperatures around normal Friday and Saturday then a
little below normal under the thick clouds and lower heights
under the trough with low temperatures a little above normal.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
At KCLT and Elsewhere: TS likely have ended at all terminals
for the night. With upper low still over the region and a very
moist easterly to southeasterly flow providing upslope lift,
additional showers really cannot be ruled out at any time. That
said, chances will be small enough to omit from TAFs for a time
later this evening. Some guidance depicts new development of SHRA
along the Blue Ridge late in the night so a mention returns later
on. Given plentiful moisture, guidance is sending a strong signal
for IFR in the early morning hours, with only KAND expected to
remain MVFR. A slow improvement is expected to VFR by midday
or early afternoon. Rain is likely at all sites by that time;
scattered to numerous TSRA are expected to break out once again
and PROB30s are already included for restrictions within those.
Outlook: An active/wet period is expected to continue through at
least Wednesday as a slow moving low pressure system impacts much of
the East. Numerous coverage of showers and thunderstorms is expected
during this period with associated lower restrictions. While
there will likely be an afternoon/evening peak in the coverage on
most days, higher-than-normal chances will also exist during the
overnight and morning hours. Drier air works in Thursday and Friday,
resulting in more typical late July diurnal convection chances.
Confidence Table...
02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 89% Med 79% Med 69% High 100%
KGSP High 90% Med 71% Med 72% High 100%
KAVL High 81% Med 65% Med 68% High 100%
KHKY High 80% Med 61% High 85% High 100%
KGMU High 98% High 86% Med 71% High 100%
KAND High 98% High 97% High 91% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...Flash Flood Watch until 6 AM EDT Tuesday for NCZ033-035>037-
049-050-056-057-068>072-082-501>510.
SC...Flash Flood Watch until 6 AM EDT Tuesday for SCZ008-009-014.
&&
$$
SYNOPSIS...DEO
NEAR TERM...RWH/Wimberley
SHORT TERM...JPT
LONG TERM...DEO
AVIATION...Wimberley
Area Forecast Discussion
National Weather Service Houston/Galveston TX
957 PM CDT Mon Jul 23 2018
.UPDATE...
Not much was changed from the previous forecast. Still carrying
20% chance for precip overnight into Tuesday morning as a frontal
boundary sags into the area. Satellite shows mid level cloud cover
increasing as mid level moistening occurs ahead of this boundary.
Short term guidance keeps suggesting that some showers and storms
could develop, but the real question is whether or not the low
levels will moisten enough to let the precip reach the ground. So
for now, isolated development is possible, but confidence in any
accumulation is pretty low. 11
&&
.PREV DISCUSSION... /ISSUED 625 PM CDT Mon Jul 23 2018/
DISCUSSION...
00Z Aviation...Added VCSH to the TAFS for late tonight and
tomorrow. Mid-level moisture increases and lowers as an upper
level disturbance moves across. Expect to see scattered high
based showers generally in the 06Z to 18Z window. There is a
small chance of some TSRA, but not very confident on the TSRA at
this time. A weak front will move into and across the area later
this evening and early tomorrow from the N/NE to the S/SW.
Therefore, we will see E/NE winds areawide tomorrow. 33
PREV DISCUSSION... /ISSUED 331 PM CDT Mon Jul 23 2018/
NEAR TERM [Through Tuesday]...
So the answer to the question "Are we going to issue another heat
advisory for tomorrow" is no. But today it is looking like the
area will experience heat index values topping out in the 107 to
110 range as expected. Mixing of drier air has happened but not as
much in some areas. Temperatures have responded increasing into
the mid 90s to low 100s from the coast towards the Brazos Valley.
The Houston area is pretty solid in the 105 to 106 heat index
value territory and could go higher over the next couple of hours.
Galveston is the place not in the 90s but that 80F dewpoint makes
it feel like 106F. Galveston does have a nice 15 mph breeze but
not sure how much that helps.
Surface analysis shows a slow moving frontal boundary stretching
across central Texas into east Texas. This boundary does push
through the area with NE winds behind it later tonight into
Tuesday. There is also some weak vorticity from a dissipated MCS
over the Red River that could track towards SE Texas tonight.
Forecast will have some slight thunderstorm chances for tonight
into tomorrow with the front mainly. Isolated strong storm could
develop this evening for areas north of Conroe with maybe
additional development after midnight. There could be some
stronger wind gusts or small hail with these storms but mainly
just sub severe winds, brief heavy rain and lightning as threats.
HREF model data shows some decent consistency with these storm
chances but not as robust with the latest HRRR runs.
Heat index values will vary from SW to NE across the area on
Tuesday. We may need an advisory for areas SW of Houston but there
is enough uncertainty to not issue an advisory for tomorrow. Heat
index values could still reach low 100s with high temperatures in
the mid 90s.
LONG TERM [Wednesday Through Monday]...
Overall it looks like the long wave jet stream pattern of the
ridge over the Desert SW/S Rockies and general troughing east of
the Rockies will hold through the next week. This should help out
temperatures but still upper 90s will be hot. Heat index values
will be closer to 102-106 instead of flirting with 107-110 like
the last few days.
Rain chances look minimal outside of the chances for Tuesday. But
forecast models are brining a stronger short wave into the main
trough this coming Sunday into Monday. A front with this system
looks decent enough to push into the area and introduce some
thunderstorm chances. Otherwise there does not appear to be any
good chance of easing summer time dry/drought conditions.
Overpeck
MARINE...
Light to moderate S/SW winds to prevail this evening with additional
weakening expected overnight with the approach of a weak front (from
the NE). The boundary is forecast to reach the bays/nearshore waters
early Tue night and then into the offshore waters early Wed morning.
Very light NE winds to develop behind this line through Wed evening.
Onshore winds to return by Thurs...and slowly strengthen through the
end of the week into the weekend. Not anticipating any advisories or
caution flags through this forecast period. 41
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 103 79 97 76 99 / 0 20 20 10 10
Houston (IAH) 99 80 96 77 98 / 0 20 20 10 10
Galveston (GLS) 90 82 91 81 90 / 0 10 20 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
Discussion...11
Area Forecast Discussion
National Weather Service Wilmington NC
939 PM EDT Mon Jul 23 2018
.SYNOPSIS...
Low pressure will develop across Georgia later today, while
offshore a large ridge of high pressure will cover the
northwestern Atlantic. Between these two systems tropical
moisture will be pulled northward, bringing several days of
showers and storms to the eastern Carolinas. Heavy rainfall is
possible, particularly near the coast. The low should weaken
late Wednesday and Thursday with showers and storms becoming
more scattered in coverage through early next week.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 845 PM Monday...FFA to remain in effect for the Coastal
Counties of the ILM CWA from Horry County northward. May have to
revisit the FFA Outline to possibly include Columbus County and
possibly even Bladen County.
Latest KLTX 88D illustrates a nice tropical feed that is
roughly 70 miles wide, pushing NNW onshore across vicinity of
Cape Fear and continuing NNW across the FA and into RAH`s and
MHX`s CWA. The portions of the ILM CWA it affects includes
eastern Brunswick, all of New Hanover and Pender counties. Once
this convective activity moves onshore, it further develops
indicative of speed or frictional convergence. This further
enhances rain rates and overall pcpn amounts. Training pcpn from
Cape Fear northward will likely be the 1st locations/areas for
possible FFW`s within the ILM CWA, if current 88D`s continue to
illustrate activity further developing after moving onshore.
Activity as it moves onshore elsewhere across the ILM CWA also
illustrates speed or frictional convergence but does not have
the long feed or training like the vicinity of Cape Fear but
nevertheless still produce decent amounts.
Previous.........................................................
As of 300 PM Monday...Satellite imagery shows a moisture laden
deep southerly flow although not purely tropical hence the
abundance of lightning. Guidance is in general agreement on at
least a couple of rounds of heavy rain moving across the Cape
Fear region tonight and according to some guidance into the day
Tuesday. The NAM is more aggressive maintaining the heavy rain
through much of the day Tuesday while the GFS has it mostly
tonight. Long story short, with at least some consensus on
timing and placement, will go ahead and hoist what has been an
almost inevitable Flash Flood Watch for the North Carolina
coastal counties and Horry county in South Carolina. Through
the near term time frame we are expecting 2-4 inches of rain
highest amounts across Pender County. Horry County is a little
iffy but if the heavy rain axis wobbles just a few miles to the
southwest they would certainly see an abundance of rain. No
changes to the temperature forecast.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...Mid level trough to our west opens up
Tuesday night. Oddly enough even though this means the feature
is weakening it still allows for height falls and PVA locally
from points west. In such an otherwise stalled pattern of deep
layer southerly flow and copious moisture this is just the
triggering mechanism for heavy rainfall that seemed might be
hard-pressed to materialize previously. As this happens the
front will be stalled very near to our western counties. This
boundary will represent the western edge of the very deep
moisture and so there will be a west-east gradient in QPF;
likely a significant one. Heading into Wednesday morning before
precipitation intensity precipitation totals should range from
1-2" inland to 2-4" coastal SC and 3-5" coastal NC. Flood
Watches hoisted by near term forecast extended into the short
term and may even need to be extended by later shifts.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 300 PM Monday...Overall troughiness at H5 remains over
the area through the period but does weaken with time. At the
surface, a frontal boundary will also remain to the north
through the period as deep muggy air mass remains in place too.
These ingredients will allow for scattered storms through the
period though they should be more diurnally driven than in
recent days. Temperatures will be seasonal with maximums mainly
in the upper 80s to lower 90s and lows in the low to mid 70s.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
As of 00Z...Plume of moisture still streaming into the region,
particularly SE NC. The HRRR model has been very consistent in
bringing in heavy showers and possible storms after 00Z. This
nocturnal convection is expected to be quite active through
08Z, with some weakening after that. It is a bit uncertain how
far south the onshore showers will go. Should get to at least
MYR, but probably will not get to FLO. Inland terminals should
see some IFR ceilings after midnight, with mainly MVFR ceilings
along the coast. Tuesday, still some convection around, however
it will mostly be confined to the afternoon and evening hours.
Extended Outlook...Occasional MVFR to IFR conditions due to
scattered SHRA and TSRA through Thursday.
&&
.MARINE...
NEAR TERM /THROUGH TUESDAY/...
As of 915 PM Monday...SCA remains in effect for all waters.
Winds have backed to SE-SSE at 10 to 20 kt with gusts to 25
kt...hier in convective gusts. Latest wind and seas guidance
specifically from Wavewatch3 and 1st look at GFS Winds indicate
a continued strong SCA to continue across all waters. The
onshore trajectory in the wind field extends well out into the
Western Atlantic. This fetch is already playing out with
significant seas having built to the 4 to 7 foot range across
the local waters.
Previous......................................................
As of 300 PM Monday...Winds and seas just about in small craft
criteria where they will remain for some time. Current winds of
15- 20 knots from the southeast will increase later this evening
to 20- 25 knots and basically remain there through the day
Tuesday. Significant seas are now near five feet in some places
and will top out at 6-8 feet later Tuesday.
SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...SCA for most of the period. Deep layer
southerly flow in place through the period. And although south to
southwesterly flow is not uncommon this time of year when the
Bermuda High is in place this is a different setup. The `normal`
Bermuda High is displaced very much eastward of its normal
position allowing for a larger and more broad fetch into the
Southeastern U.S. Much of the resulting larger period swells
will remain to our east but 6ft advisory-worthy waves will
likely be observed along the outer portions of the 20nm zones
for most if not all of the entire period. The exception may be
SC waters late in the period where they drop out.
LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 300 PM Monday...S to SW winds of 15 KT or less are
expected through the period. Seas of 3 to 5 FT early Thursday
will diminish to 2 to 3 FT by Saturday afternoon with 4 footers
possible at 20 NM northern waters.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...Flash Flood Watch through late Tuesday night for SCZ054-058.
Beach Hazards Statement from 8 AM EDT Tuesday through Tuesday
evening for SCZ054-056.
High Rip Current Risk from 8 AM EDT Tuesday through Tuesday
evening for SCZ054-056.
NC...Flash Flood Watch through late Tuesday night for NCZ105>110.
Beach Hazards Statement from 8 AM EDT Tuesday through Tuesday
evening for NCZ106-108.
High Rip Current Risk from 8 AM EDT Tuesday through Tuesday
evening for NCZ106-108-110.
Coastal Flood Advisory until 9 PM EDT this evening for NCZ107.
MARINE...Small Craft Advisory until 3 PM EDT Wednesday for AMZ250-252-
254-256.
&&
$$
SYNOPSIS...SHK
NEAR TERM...DCH/SHK
SHORT TERM...MBB
LONG TERM...RAN
AVIATION...HDL
Area Forecast Discussion
National Weather Service Lincoln IL
912 PM CDT Mon Jul 23 2018
.UPDATE...
Issued at 910 PM CDT Mon Jul 23 2018
Forecast generally looks on track tonight across central IL and
just a minor update to cloud cover tonight. Broken 5-10k ft
clouds holding on a bit longer in eastern IL, especially counties
along the Indiana border. These clouds associated with elongated
upper level trof east of IL extending from lower MI southward
through eastern KY/TN and into GA. Very isolated showers earlier
this evening near the IL river valley and along the IN border have
dissipated with sunset. Continued mention of patchy fog overnight
into early Tue morning east of the IL river with light winds and
mostly clear skies overnight allowing temps to cool toward
dewpoints in the low to mid 60s by dawn. Any fog that develops
overnight will be shallow and quick to burn off shortly after
sunrise Tue.
&&
.SHORT TERM...(This evening through Tuesday)
ISSUED AT 253 PM CDT Mon Jul 23 2018
Elongated upper low extending from the Great Lakes southward to
the Gulf Coast continues to influence the weather across central
Illinois this afternoon...as 19z/2pm visible satellite imagery
shows robust diurnal cloud elements developing in the vicinity of
this feature as far west as the Illinois/Indiana border. Regional
radar mosaic indicates a few light showers across north-central
Indiana, and based on satellite trends, would not be surprised to
see isolated showers developing east of the I-57 corridor over the
next couple of hours. Any showers that manage to form will quickly
dissipate toward sunset, followed by mostly clear skies across the
board tonight. With clear skies, NW winds diminishing to 5kt or
less, and surface dewpoints hovering in the lower to middle
60s...think patchy fog will once again develop late tonight. While
the RAP and HRRR show no visby restrictions across the area, the
NAMNEST is suggesting the possibility of fog everywhere east of
the Illinois River. Based on a consistency forecast from last
night, will include patchy fog toward dawn across all but the far
western KILX CWA. Low temperatures will drop into the lower to
middle 60s. Mostly sunny and dry conditions will be in store for
Tuesday, with high temperatures topping out in the middle 80s.
.LONG TERM...(Tuesday night through Monday)
ISSUED AT 253 PM CDT Mon Jul 23 2018
High pressure will control the weather across central Illinois on
Wednesday...providing mostly sunny skies and seasonable
temperatures in the middle 80s. As the high departs, a weak cold
front will drop into the region on Thursday. Deep-layer moisture
will be limited: however, decent convergence along the boundary
will be enough to trigger widely scattered showers and thunderstorms
during peak heating Thursday afternoon...particularly along/south
of the I-70 corridor. Once the front passes, cooler and less humid
conditions will be on tap for the end of the week.
The overall synoptic pattern in the extended will favor slightly
below normal temperatures, as the Midwest/Ohio River Valley remain
locked in a W/NW upper flow regime between a prevailing upper
high over the Desert Southwest and a deep trough over eastern
Canada/New England. The next significant short-wave trough
expected to track through the northwesterly flow will likely not
impact the area until next weekend. Model track/timing
discrepancies are expected at this time range, so timing of precip
chances will likely be adjusted over the next couple of days. At
this time, it appears the best rain chances will hold off until
late Saturday into Sunday as a pair of waves track through the
region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 659 PM CDT Mon Jul 23 2018
Very isolated showers have passed south of PIA early this evening
and were currently located east of the IL river and west of I-55.
Believe these will dissipate toward sunset as they slowly drift
south and should not affect central IL airports. Scattered to
broken 5-9k ft clouds to diminish by mid evening and last longest
in eastern IL at CMI which is more influenced by elongated
mid/upper level trof over the eastern U.S. Patchy fog will develop
overnight especially east of the IL river and dissipate between
12-13Z Tue. NAMNest model continues to be most aggressive with fog
development east of the IL river, while HRRR, RAP and GFSLamp
models much less fog development in eastern IL. Will continue MVFR
vsbys of 3-5 miles east of the IL river between 09-13Z, lowest
vsbys at CMI. Otherwise few cumulus clouds and scattered cirrus
clouds expected Tue. NW winds of 5-10 kts early this evening
diminish light after sunset, then NW at 5-10 kts again after 14Z/9
am Tue.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...07
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...07
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
837 PM EDT Mon Jul 23 2018
.SYNOPSIS...
A broad and slow moving low pressure system over the Southeast
will influence the Mid Atlantic through the middle of the week.
A pair of cold fronts will move through the area during the
second half of the week.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
A deeply amplified trough axis remains across the Great Lakes
and Ohio Valley. A plume of rich moisture (precipitable water
value on 00z IAD sounding is 2.09") resides across the area.
There has been scattered shower and isolated thunderstorm
activity across the region through the afternoon, but
coverage/intensity has not been particularly widespread/intense.
Overall moisture has been on the increase this evening noted by
water vapor plume moving in from the south where convection has
seen greater coverage. Recent model runs, including the
convective allowing NAM3KM and HRRR show an increase in
coverage/intensity overnight as greater moisture/convergence
move overhead. If this does occur, this would increase risk of
flash flooding given high precipitable water values and warm
rain processes. Flash Flood Watch remains in effect. Lows in
the upper 60s to mid 70s.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
The axis of high precipitable water (2.0-2.5 inches) shifts west
Tuesday morning, with another mid level jet impulse streaming
across the area. Given practically the same synoptic scale
ingredients as past few days, anticipate the same results.
Database contains cat PoPs for repeated sounds of
showers/thunderstorms. Heavy rain the big concern. Given that
and saturated antecedent conditions, Flash Flood Watch has been
extended through Tuesday evening.
Deep moisture plume will start shifting a bit more east on Wed
with flooding threat diminishing somewhat for western areas but
remaining very high for eastern areas Wed. Mid-level drying will
start taking place late Wed night with convection and risk of
flooding likely decreasing substantially after midnight Wed
night.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
On Thursday, the upper level trough that has been sitting off to our
west will break down and shift eastward out of our region. The
region will see a brief drying out as Precipitable water values drop
below two inches with most areas being below a inch and half. The
decrease in moisture will lead to dry conditions on Thursday with
clearing skies to partly cloudy. Winds will be light out of the west
to southwest with temperatures reaching into the mid to upper 80s
range.
Friday through Sunday, a upper level 500mb trough will approach our
region from the north. A low pressure system to the east of the
trough and its corresponding cold front will approach from the
west. Thunderstorms and showers will be possible both Friday and
Saturday. It seems that storms will be limited in the their
intensity due to the lack of moisture with this system as the models
are forecasting precipitable water values around the inch and half
mark or lower. The cold front is expected to move through our region
during the early parts of this weekend and then linger to the
southeast of our region over southern Virginia and Northern North
Carolina. Some showers and storms will be possible on Sunday.
Temperatures are expected to warm up into the upper 80s to mid 90s
this weekend.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Conditions will generally fall into MVFR this evening and
overnight as ceilings lower, except IFR likely at CHO.
Scattered shower/thunderstorm activity is expected to increase
overnight and into Tuesday, and periods of IFR visibilities are
expected in heavier rain. This will persist through Tuesday
night.
Pattern continues into Wed with training convection likely.
Several round of brief/local aob IFR anticipated.
On Thursday, skies will clear some leading to rising cloud levels
and breaking up of cloud cover. We expect a drying trend with no
precipitation expected on Thursday. Winds will be light out of the
southwest to west. VFR conditions are likely.
Friday, a cold front will approach from the west. Winds will remain
light but shift out of the south. Showers and thunderstorms will be
possible. SubVFR conditions will be possible.
&&
.MARINE...
Intervals of scattered-numerous showers/thunderstorms
anticipated into Wed. Special Marine Warnings may be required.
In addition to that, SCA conditions likely into Wed. Have
extended SCA into Tue night at this time.
Clearing skies and light winds out of the west to southwest is
expected on Thursday. The west to southwesterly flow will not allow
for much of fetch which likely means winds will remain light over the
bay.
Showers and storms will be possible. Winds will shift out of the
south which could lead to conditions that will be favorable for
winds to reach above 15 knots.
&&
.HYDROLOGY...
Repeated rounds of showers and thunderstorms through Wednesday
will lead to increasingly susceptible conditions for not only
flash flooding but eventually some river flooding. Soils
already saturated, so it won`t take much to realize flood
concerns. Flash Flood Watches have been extended through Tuesday
evening. In addition, River Flood Watches in effect for several
points in the Potomac and Rappahannock basins, mainly in the
east. Warnings are also in effect for Frederick and Dawsonville.
Please refer to AHPS for details.
&&
.TIDES/COASTAL FLOODING...
Water levels continue to run well above normal (1.5 to 2 feet) due
to persistent onshore flow. Widespread minor flooding is anticipated
through tonight, with moderate flooding forecast at Annapolis. Water
levels may begin to (very) gradually decrease after tonight as winds
start to shift to more southerly and eventually southwesterly, but
the threat of flooding will exist around high tide through the
middle of the week.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Flash Flood Watch through late Tuesday night for DCZ001.
Coastal Flood Advisory until 9 AM EDT Tuesday for DCZ001.
MD...Flash Flood Watch through late Tuesday night for MDZ003>006-
011-013-014-016>018-503>508.
Coastal Flood Advisory until 4 AM EDT Tuesday for MDZ016-018.
Coastal Flood Advisory until 4 AM EDT Tuesday for MDZ017.
Coastal Flood Warning from 1 AM to 7 AM EDT Tuesday for MDZ014.
Coastal Flood Advisory until 1 AM EDT Tuesday for MDZ014.
Coastal Flood Advisory from 7 AM to 10 AM EDT Tuesday for
MDZ014.
Coastal Flood Advisory until 10 AM EDT Tuesday for MDZ011.
VA...Flash Flood Watch through late Tuesday night for VAZ025>031-
036>040-050>057-501-502-505>508.
Coastal Flood Advisory until 4 AM EDT Tuesday for VAZ057.
Coastal Flood Advisory until 9 AM EDT Tuesday for VAZ054.
WV...Flash Flood Watch through late Tuesday night for WVZ051>053.
MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ530>543.
&&
$$
SYNOPSIS...HTS
NEAR TERM...MM/HTS
SHORT TERM...HTS
LONG TERM...JMG
AVIATION...MM/HTS/JMG
MARINE...MM/HTS/JMG
HYDROLOGY...MM/HTS
TIDES/COASTAL FLOODING...MM/HTS/DHOF
Area Forecast Discussion
National Weather Service Pueblo CO
913 PM MDT Mon Jul 23 2018
.UPDATE...
Issued at 906 PM MDT Mon Jul 23 2018
Updated to expire the severe thunderstorm watch for this evening.
The flash flood threat will continue. Radar indicates
thunderstorms will locally heavy rainfall moving across the
Plains. More scattered activity is currently moving across the
western half of the CWA. Expect these storms to move east into the
Plains overnight. Locally heavy rainfall will remain possible, and
flash flooding may be likely on areas that have already been
saturated with earlier rains. Mozley
UPDATE Issued at 655 PM MDT Mon Jul 23 2018
Updated to extend the Severe Thunderstorm Watch until 9 PM for
much of southern Colorado, and expanded to include Prowers, Bent
and Baca Counties. Heavy rainfall will remain the primary threat.
A few of the stronger storms will be capable of hail up to ping
pong ball size hail and winds gusting in excess of 60 mph. If you
are caught in flash flooding, do not drive into it...remember,
turn around, don`t drown. Mozley
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 303 PM MDT Mon Jul 23 2018
...Heavy rain and severe storms possible through this evening...
Currently...
Bulk shear is running higher than previously expected...40-50
knots across parts of the Pikes Peak Region. Additionally, Mixed
Layer CAPES are running an estimated 1,000-2,000 J/kg. With
steepening mid level lapse rates through the afternoon, should all
be sufficient for rotating storms. Plus, high res models are
showing supercellular structures, particularly over the Pikes
Peak Region. As storms continue to evolve through the afternoon
into the evening, bowing structures noted...suggestive of high
wind potential. Also, some initial quarter size hail possible
mountains and immediately adjacent plains as storms get going
this afternoon. So, a Severe Thunderstorm Watch is now in effect
until 7 this evening. The Flash Flood Watch also remains in
effect. Busy weather ahead in the short term. lw
For later tonight...HRRR shows a secondary round of stronger
convection moving across the greater Pikes Peak region from mid
evening to around midnight. Dunno if this will come to pass as
HRRR is notorious for producing 2nd rounds of storms and not
materializing (or much weaker than initially forecasted). For now
will draw up fcst based on HRRR output and keep convection going
through the nighttime hours going on the plains.
Tomorrow...
Anticipate most of the activity tomorrow will be over the mountains
as plains at this time appear to be too stable and relatively drier.
With precip over the mtns, burn scar flooding will be the main
concern tomorrow, especially the Spring burn scar.
.LONG TERM...(Tuesday night through Monday)
Issued at 303 PM MDT Mon Jul 23 2018
...Active Thunderstorm and Locally Heavy Rain Pattern to Continue...
Southern Colorado will remain in an active monsoon pattern through
the week. The center of a large upper level high pressure system
will remain over the southwest U.S. through the period. This will
allow monsoon moisture to rotate around the high, adjoin with
shortwaves moving over the top of the ridge, and then enter the
eastern plains through the back door. Forecast models have
shortwaves moving through the stronger flow to the north, clipping
southern Colorado almost daily through the weekend, before things
start to dry out early next week. This is a good setup for rain
across the eastern slopes and plains as each shortwave will help to
initiate and organize convection. Also, each shortwave will likely
send a boundary south which will help to focus low level moisture.
The combination of the two will help to realize all the monsoonal
moisture that is available in the atmosphere. With each day that
passes this week, antecedent soil moisture will increase. As a
result, the flash flood threat will escalate over time. Burn scars
will be primary targets for flash flooding through the week but
urban areas will also be prime targets.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 303 PM MDT Mon Jul 23 2018
Thunderstorms and low cigs will be the primary issues at KCOS and
KPUB rest of today and this evening. Storms will move over the
region this afternoon, with a secondary round being indicated by the
short range guidance later this evening. Low cigs will be likely at
both KPUB and KCOS tonight into tomorrow morning. Thunderstorms will
likely remain over the mtns tomorrow.
KALS will be VFR, with isold TSRA during the afternoon and
evening.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until midnight MDT tonight for COZ072>089-
093>099.
&&
$$
UPDATE...MOZLEY
SHORT TERM...HODANISH
LONG TERM...LW
AVIATION...HODANISH
Area Forecast Discussion
National Weather Service Raleigh NC
1021 PM EDT Mon Jul 23 2018
.SYNOPSIS...
An occluded cyclone over the southeastern US will continue to fill,
while lifting northeastward across the southern and central
Appalachians and Carolinas, through Wednesday night.
&&
.NEAR TERM /TONIGHT/...
As of 1010 PM Monday...
00Z upr air data depict a vertically-stacked, occluded cyclone over
GA; and model guidance suggests this feature will remain quasi-
stationary tonight, while weakening (another 10-20 meters through
12Z Tue). Deep, ssely flow, between the cyclone and a large ridge
over the wrn N. Atlantic, will continue to direct a plume of
tropical moisture characterized by precipitable water values aoa 2.0
inches across the srn middle Atlantic coast. Embedded within and on
the wrn edge of that tropical moist axis, WV satellite imagery
depicts a couple of impulses centered near SAV, and from near FLO to
a couple of hundred miles east of SAV, respectively. These features
will pivot nnwwd across the cntl Carolinas tonight.
At the surface, a quasi-stationary front was analyzed at 02Z from
nne to ssw across cntl VA and NC, then swwd to a 1010 mb low over
cntl GA. Temperatures on the cool side of the boundary ranged from
upr 60s to lwr 70s, including over the wrn/srn NC Piedmont, to mid
70s to around 80 degrees east of the front, with associated
objectively-analyzed MLCAPE ranging from around 500 J/kg west to
1500 J/kg east.
While there has been a relative lull in convection during the past
couple of hours, the nnw pivot of the aforementioned impulses aloft,
and accompanying increase in 925-850 moisture transport across ern
NC, will support the development of bands of showers and storms from
offshore, nwwd into the ern half of cntl NC/roughly along and east
of the aforementioned frontal zone, overnight - generally supported
by recent HRRR runs and latest regional radar trends. Weak(er than
last evening) mid level lapse rates -around 5.5 to 5.75 C/km- and
DCAPE of less than 1000 J/kg in a narrow axis roughly coincident
with the surface frontal zone, suggests the severe weather threat
will be low. Wind gusts up to 45 mph, driven primarily by forward
(nwwd storm) motion and momentum transport 25-30 kt of lower
tropospheric sely flow, may nonetheless down a tree or three. Flash
flooding will instead pose the primary risk, particularly if one of
the convective bands intersects the main axis of heavy rain from
this past morning, from near and just west of FAY nwd to IGX and
TDF.
Lastly, areas of fog, some, probably dense, are likely to develop on
the cool side of the front late tonight-early Tue, with lows
generally in the upr 60s to lwr to mid 70s.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
As of 330 PM Monday...
Persistent pattern will support a continued threat of flash flooding
across central NC on Tuesday and Tuesday night. The upper-level
trough near and just west of the Appalachians will continue to
produce deep layer southerly flow. Disturbances in the circulation
around trough in an unstable air mass will continue to result in
numerous showers and thunderstorms. The greatest convective coverage
and intensity will be during the afternoon and evening but high
chance to likely PoPs will be included throughout the period. Urban
areas appear most at risk of flooding but training convective
clusters support a flood risk even in the rural areas. Hard to
describe rainfall amounts but large basin averages of 1 to 3 inches
appear likely with localized amounts in excess of 4 to 5 inches
possible. Highs Tuesday will generally be in the lower to mid 80s
with lows in the upper 60s to lower 70s. -Blaes
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
As of 220 PM Monday...
The active/wet pattern is likely to continue through most of the
long term period as the area finds itself sandwiched between a
stalled mid/upper-level trough (west) and a sub-tropical Atlantic
ridge (east). This will exacerbate southerly/southwesterly fetch
across central NC, providing an airmass characterized by high PWAT
values (consistently in the 1.75 to 2.5 inch range) and persistent
diurnal shower/thunder chances. The trough is expected to flatten a
bit on Thursday/Friday, cutting POPs to more CHC/SCHC briefly,
before returning to more CHC/LKLY over the weekend as a frontal
boundary stalls over our area.
QPF amounts are going to be difficult to nail down due to the
convective nature of the precipitation. As an area average, expect
generally 1 to 3 inches of rain during this period, with locally
higher amounts possible, especially across the coastal plain.
Flooding concerns will generally be locally dependent on high
rainfall rates and/or training storms across a particular area, but
with already wet antecedent conditions, the likelihood of flash
and/or river flooding will continue to rise slowly through the
period. Currently, not a strong signal for potential river flooding
according to MMEFS, but with high QPF amounts expected across the
headwaters region in VA/western NC areas over the next 7 days, it
could easily transition into more of a concern eventually.
With boundary layer moisture ample through the period, thicknesses
are expected to remain generally near to slightly below normal
thanks in large part to persistent cloud cover and/or shower
development during prime daytime heating hours. Expect temperatures
generally in the mid 80s to begin the period, with 90-92 Thu/Fri/Sat
as SHRA/TS chances decrease slightly, and a mid to upper-level low
is forecast to transverse through the Great Lakes region to begin
the weekend, dropping a cold front into our vicinity. Lows will
generally settle a bit warmer than normal, generally in the low to
mid 70s during throughout the period.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
As of 825 PM Monday...
Aviation conditions are mostly VFR at the moment but will
deteriorate later tonight, especially at INT/GSO, where a light wind
from the NE will foster development of IFR/LIFR stratus after 05Z,
lasting until around 13z, along with MVFR to IFR fog. RDU/RWI/FAY,
which will be within a low level flow from the SE, will have a lower
chance of sub-VFR conditions, with cigs expected to briefly drop to
MVFR 07z-12z late tonight/Tue morning. And, at about any time
tonight through Tue, scattered to numerous showers and storms could
impact any of the central NC terminals, bringing briefly strong,
shifting winds gusting to around 40 mph and low vsbys in torrential
downpours. The best chance of such conditions will be FAY/RWI and
perhaps RDU 06z-12z tonight/Tue morning. Cigs will gradually lift
late morning Tue, to MVFR at INT/GSO and to VFR at RDU/RWI/FAY. More
showers and storms are expected Tue afternoon, mainly after 18z.
Looking beyond 00z Wed, unsettled weather will hold through mid
week. Numerous showers/storms will persist Tue night through Wed
evening, producing areas of sub-VFR conditions and gusty surface
winds. The greatest shower/storm coverage will shift east of our
area starting late Wed night, although FAY and RWI may continue to
see scattered to numerous storms each afternoon/evening, with a
lesser chance further west at RDU/INT/GSO.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through late Tuesday night for NCZ007>011-
021>028-038>043-073>078-083>086-088-089.
&&
$$
SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...BLAES
LONG TERM...JM
AVIATION...Hartfield
Area Forecast Discussion
National Weather Service Blacksburg VA
923 PM EDT Mon Jul 23 2018
.SYNOPSIS...
A broad area of upper level low pressure with an associated
stalled surface front will linger across much of the region through
midweek resulting in periodic rounds of showers and storms
tonight through Wednesday. These features will push east later
in the week with somewhat drier air following under weak high
pressure for Thursday into Friday.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 915 PM EDT Monday...
Elongated upper low with centers to the northwest and southwest
of the area continues to spin faint disturbances across the
region resulting in bands/clusters of showers/storms this
evening. However coverage and intensity continue to decrease as
the residual wave over the Carolinas from earlier slides north
into less unstable air at the moment. Latest Cams still suggest
added redevelopment within a tropical type environment overnight
as another impulse slides across eastern sections late. This
supports perhaps another round of heavy rain espcly eastern half
and with Pwats of better than 1.5 inches could see spots get
enough rain in a short period for flooding but iffy. Otherwise
few changes to the going updated flood watch with some adjusts
in pops to cover current coverage while leaving high pops east
overnight for another round late. Few changes to lows with most
in the 60s to around 70 given lingering moisture around.
Update as of 730 PM EDT Monday...
With bands of heavier rain heading north into eastern slopes of
the Blue Ridge, went ahead and filled in the gap in the flash
flood watch to include areas from Lynchburg north and west
overnight. Also adjusted pops to reflect this trend and to lower
over the southeast where organized convection has exited. No
other changes for now.
Previous as of 300 PM EDT Monday...
Little change to the overall pattern during the forecast period
as the upper level low that is over most of the eastern US will
weaken slightly but remain an elongated trough. This will
continue to pump moisture into the region which in turn will
continue to drive the prevailing cloudy, relatively cool and
rainy conditions. SPC does have most of the forecast area
outlooked with a marginal risk of severe, however any severe
weather is likely to be highly localized to areas that may
potentially get a break in the clouds and get a little edge in
heating today. The more prominent threat for the day will be
flooding. The past few runs of the HRRR have suggested that
coverage today will not be as widespread as yesterday, however
now with antecedent conditions being more saturated than they
have been in awhile, any short heavy downpour could cause
hydrologic issues rather quickly. WPC has the area outlooked
with a slight risk of flash flooding through the period, with a
nose of moderate risk sneaking into the northeast counties
tomorrow.
Regarding a near term flooding threat, current satellite is
showing development of some storms south of Winston-Salem along
an outflow boundary. Beyond that, multiple models are picking up
on a rather decent swath of rain piercing into the forecast area
though Stokes/Surry/Yadkin counties and well into VA. Therefore,
a flash flood watch has been issued for all of the NC Counties
and most of the southern half of VA counties until 09Z.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 300 PM EDT Monday...
With the dissipation and assimilation of the closed low along the Gulf
coast back into the mean flow, the upper pattern will trend to a more
typical eastern trof with a closed low moving across southern Canada
toward the Great Lakes. This will eventually help nudge the stalled
frontal boundary over the region off to the east . So after one more
soggy period Tuesday night/Wednesday the Appalachians and
central mid Atlantic region will start to dry out a bit for the
end of the week.
Convection that fires on Tuesday will continue into into Tuesday
evening with locally heavy rainfall before winding down overnight.
Precipitable water values through Wednesday will still be quite juicy
with amounts around 2 inches east of the Blue Ridge and model soundings
still show deep layer instability, though dynamic support for organized
severe weather continues to be lacking. This combination of factors
will bring one last round of thunderstorms with heavy rainfall and
potential flooding to the region, with the flood threat lessening
moving westward into the Mountain Empire and deeper into southeast West
Virginia. Up to another 1.5 inches of rain with locally higher amounts
is expected Tuesday night/Wednesday afternoon along and east of the
Blue Ridge. It is worth noting that the threat for more widespread
flooding problems on Wednesday will be dependent on where any heavy
rain falls both today and Tuesday. Additional rainfall
Temperatures will remain below normal on Wednesday, but with a return
to more sunshine for Thursday readings will warm into the lower 90s
east of the Ridge with middle 80s to the west. Lows will generally be
in the 60s.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 300 PM EDT Sunday...
The closed low over southern Canada near the Great Lakes will move off
to the northeast by this weekend, leaving a lower amplitude trof over
the east with a ridge off the Atlantic coast. This looks to keep the
frontal boundary at the surface just off to our east, and with high
pressure over the Ohio valley building in with northwesterly flow this
should continue to help limit development of showers/storms to
scattered activity mainly in the mountains. By Saturday the high will
give way to an inverted trof over the mountains that will start to
increase our chances for showers/storms once again, especially along
the southern Blue Ridge.
For Sunday, high pressure over the Atlantic will combine with a weak
cold front approaching from the west to create deep moisture transport
into the region from the southwest. This will bring an increase to
coverage of showers and thunderstorms to the forecast into the first
part of next week.
After a warm start, increasing clouds and precipitation will trend
temperatures back to below normal by the first part of next
week.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
As of 658 PM EDT Monday...
Still expect ceilings to be highly variable during the forecast
period with rounds of showers and storms resulting in periods of
sub-VFR cigs/vsbys at times overnight and again by Tuesday
afternoon. In between will see areas of stratus and some fog
resulting in IFR conditions espcly where earlier rain has
occurred. This mostly in the late tonight to early Tuesday
morning period espcly valley locations and from the Blue Ridge
east. Thus will continue with local reductions due to
shower/storms where ongoing this evening at release, and cover
overnight with lingering vicinity or TEMPO mention before
lowering most sites to a period of stratus/fog late.
Should see best coverage of showers and storms in the east on
Tuesday as another wave rides up within the upper low aloft and
beneath via easterly low level convergence into the stalled
surface front. Appears this could again occur from late morning
through Tuesday afternoon so reflected with more prevailing
nature showers from KROA east with a vicinity mention for
thunder. Coverage likely a bit less to the west where more
isolated nature bands/clusters more probable, so only including
a VCTS over far western locations for now. Otherwise looking at
only a brief improvement in conditions from early fog/stratus
east to periods of sub-VFR in shra/tsra at KLYH/KDAN and
perhaps more afternoon VFR west. Winds mainly east to southeast
at 5 to 12 kts Tuesday.
Extended Aviation:
Intervals of poor flying conditions will persist into midweek as
deep moisture lingers and helps redevelop convection espcly with
heating during the afternoon/evening hours through Wednesday.
Should see some improvement by Thursday into Friday as moisture
shifts east ahead of additional cold fronts entering from the
northwest by weeks end. This should allow for more in the way of
VFR with only isolated convection until Saturday when coverage
could increase a bit more with perhaps a boundary lingering
nearby. Otherwise looking at rather extensive cloud cover with
ceilings varying through all categories into Wednesday before
improving. However typical late night/early morning fog/stratus
likely to allow for brief periods of sub-VFR going each day with
coverage becoming less by the weekend.
&&
.HYDROLOGY...
As of 330 AM Monday...
Still not expecting river flooding under the current scenario
given the intermittent rainfall pattern so far and what is
forecast. Rainfall has been quite variable so far with very
little in the upper James River basin and the highest amounts
in the Dan River basin. Short-fuse impacts likely will be
limited to pockets of heavy rainfall causing localized runoff
problems and possibly a few flood advisories. Isolated flash
flood warnings possible but will require repeated convection
over the same small basins.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Flash Flood Watch until 5 AM EDT Tuesday for VAZ012>017-
022>024-032>035-043>047-058-059.
NC...Flash Flood Watch until 5 AM EDT Tuesday for NCZ001>006-
018>020.
WV...None.
&&
$$
SYNOPSIS...JH/JR
NEAR TERM...JH/JR
SHORT TERM...MBS
LONG TERM...MBS
AVIATION...JH/JR/PC
HYDROLOGY...PC
Area Forecast Discussion
National Weather Service Las Vegas NV
715 PM PDT Mon Jul 23 2018
.SYNOPSIS...Thunderstorm development will largely be inhibited
across much of the region except the southern Sierra and high
mountains as a strong area of high pressure builds over the
southwest states. This will lead to dangerously hot conditions
across the Mojave Desert and southern Great Basin much of this
week.
&&
.UPDATE...A few storms remain this evening mainly across western
Inyo county and near the Sierra. Despite moderate instability in
place across much of the region, building high pressure overhead has
led to widespread subsidence, limiting thunderstorm strength and
coverage. With loss of daytime heating, any remaining storms this
evening will quickly die off after sunset. Updated the forecast
grids to account for current trends but the overall forecast remains
in good shape.
-Outler-
&&
.SHORT TERM...through Thursday night.
Thunderstorms will be most active over the southern Sierra the
rest of the afternoon and early evening. Isolated cells developing
over the mountains from the Mojave National Preserve up across
Clark and into Lincoln County will remain mostly fixed near the
mountains. The latest HRRR indicates outflow may push south
of convection from central Nye and Lincoln counties this evening.
The most significant impact for our region will be excessive
heat as temperatures continue climbing Tuesday and approach record
levels Wednesday and Thursday. Thunderstorm development will
be a little more sparse Tuesday through Thursday as the dome
of hot air moves over the region.
.LONG TERM...Friday through Monday.
Models call for a cooling trend beginning Friday which returns
temperatures closer to normal over the weekend. Kept slight chance
of thunderstorms over southern Mohave and parts of eastern and
southern San Bernardino counties Saturday and Sunday with models
forecasting a weak disturbance approaching from the south where the
better moisture is pooled.
&&
.CLIMATE...Very hot - near record - temperatures are expected
Tuesday through Friday this week. The table below shows the
record temperature this week and the year recorded for McCarran
(Las Vegas), Death Valley, Needles, Barstow/Daggett, Bishop
and Kingman.
RECORD HIGH TEMPERATURES (YEAR)
---------------------------------------------
TUE (7/24) WED(7/25) THU(7/26) FRI(7/27)
LOCATION ---------------------------------------------
McCarran | 117 (1942) 115(1942) 116(1943) 115(2016)
Death Valley | 126 (2006) 126(2006) 127(1933) 127(1933)
Needles | 119 (2006) 120(1943) 118(1959) 119(2016)
Barstow/Daggett | 112 (2016) 115(1975) 114(1995) 115(1995)
Bishop | 107 (2016) 107(2016) 108(1975) 108(2016)
Kingman | 107 (1928) 107(1943) 108(1934) 108(1934)
&&
.AVIATION...For McCarran...An area of high pressure will
strengthen over southern Nevada reducing thunderstorm
development this week. Winds will favor typical diurnal
directions with speeds generally less than 8 knots.
There is a slight chance that outflow from storms near the
Nevada National Security Site could blow into the Vegas Valley
later this evening.
For the rest of southern Nevada, northwest Arizona and southeast
California...Thunderstorms over the southern Sierra and high
mountains of the southern Great Basin will dissipate after sunset.
Isolated thunderstorms will develop Tuesday afternoon primarily
over the southern Sierra. The rest of the region should see
generally tranquil weather with winds less than 15 knots and
FEW-SCT clouds with bases above 12 kft.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
SHORT TERM/AVIATION...Adair
LONG TERM...Salmen
CLIMATE...Boothe
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