Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/18/17
Area Forecast Discussion
National Weather Service Caribou ME
1013 PM EDT Mon Jul 17 2017
.SYNOPSIS...
A weak front will remain nearly stationary across northern
Maine tonight. A weak cold front will cross the area Thursday
and will be followed by a stronger cold front Friday. Weak high
pressure will build into the area Saturday.
&&
.NEAR TERM /THROUGH TUESDAY/...
1000 PM Update: HRRR Meso-model output is doing a good job with
the demise of organized cnvctn ovr the NW, with radar ref
showing a faster decrease in ref ovr the last hr to hr and a
hlf. We removed the mention of enhanced tstm elements from the
fcst for the remainder of the ngt ovr the NW and the potential
of isold tstms xpctd to end by mdngt.
Otherwise...with more in the way of LLVL srly winds abv the BL,
latest SREF guidance indicates a more rapid xpnsn of ST, at
least patchy fog and dz into Cntrl ptns of the Rgn by the late
ngt and Nrn ptns by daybreak with fcst hrly cld cvr updated to
reflect this line of thinking. Of course, fcst hrly temps/dwpts
into the late ngt were updated based on latest trends seen with
mid/late eve sfc obs, with ovrngt lows lowered a couple of deg F
ovr Nrn Somerset due to rn cooled air already close to prior
fcst ovrngt lows ovr this ptn of the Rgn.
Orgnl Disc: Showers and thunderstorms had a bit of a hard time
getting their act together this afternoon, but they are now
popping up in earnest as a weak upper shortwave lifts across
central New England. These showers/thunderstorms will be mainly
scattered through early evening, with the most persistent
activity stretching across the Katahdin region and North Woods.
Much of the hi-res guidance, including the HRRR, NMM, RAP, and
ARW all show the upstream convection across VT holding together
and hitting our western areas as a fairly consolidated line
sometime in the 6pm to 8pm timeframe. This line should weaken as
it moves eastward, but it may still be strong enough to produce
gusty winds, small hail, and heavy rainfall in far western
portions of our forecast area. Have therefore kept the enhanced
wording in for the next several hours. All convection will
pretty much dissipate by midnight with some showers persisting
over the higher terrain in the North Woods. The concern then
becomes yet another night of fog and low stratus. Moisture
profiles along the coast look conducive for drizzle, as well.
Lows will be in the lower to mid 60s.
For Tuesday...the weakening upper trough will finally swing across
the region, producing yet another day of afternoon showers and
thunderstorms, especially across the north and west. Instability
doesn`t look nearly as good as what we`ve seen over the past couple
of days, so don`t anticipate any strong storms. However, with plenty
of moisture to work with, locally heavy rainfall will be a threat.
Highs will be in the mid 70s to around 80 in most spots, with the
coast in the mid 60s to lower 70s.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
A mid level trough axis along the Maine/NB border late Tue afternoon
moves east into NB Tue evening and is briefly followed by a weak
ridge. Any thunderstorms Tue evening should end with the loss of
daytime heating. The threat of showers will diminish too, but with a
mild and muggy air mass an isolated shower can`t be ruled out
through late evening. There will likely be some areas of fog,
especially over the coastal waters and along the Downeast coast. On
Wednesday, a weak surface trough moving into Maine will provide the
focus for isolated to scattered showers and storms, mainly during
the afternoon and evening. As a weak trough moves to the Downeast
coast Wed night and there could be just enough convergence and
moisture around for an isolated shower. Once again there will
likely be areas of fog around, most widespread along the coast.
Very brief surface ridging is expected for Thu morning ahead of
an approaching cold front that will be organizing to the west
across Quebec during the afternoon. As the front draws closer to
the region in the afternoon the chance of showers and storms
will be on the increase, especially across northern and western
portions of the CWA.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A cold front is expected to cross the area later Thu night into Fri
with showers and thunderstorms. The timing of the frontal passage
and cloud cover will be important factors as to whether any of the
storms can become strong or severe. The front pushes off the coast
Fri evening and is followed by drier/cooler air Saturday. The next
system across the Great Lakes begins to approach Sun with the chance
of an afternoon shower or thunderstorm, mainly across the northwest
half of the CWA, but it is possible that any activity could hold off
all day as there remain timing differences between the models and
model ensembles. The system coming in from the Great Lakes
will likely produce some showers and the chance of thunderstorms
Sun night and Monday along with a more humid air mass.
&&
.AVIATION /22Z MONDAY THROUGH SATURDAY/...
NEAR TERM: VFR conditions will prevail through 03z Tuesday.
Scattered showers and thunderstorms are possible at CAR/PQI/FVE
through 03z Tuesday, and these may produce local MVFR or IFR.
Thereafter, expect all sites to see ceilings below 1000 ft and
visibility of 2 miles or less in fog and low stratus, starting
at BHB at 03z and reaching FVE at 08z Tue. These conditions will
persist until 13z, then all sites will improve to VFR with
scattered afternoon showers.
SHORT TERM: Conditions will be variable. Mainly VFR at the northern
terminals, but briefly lower conditions are expected in any fog at
night/early morning and in showers and t-storms. At KBHB there
will be times of VLIFR in low cloud/fog, especially at night and
early morning, with mainly VFR from the mid morning hours into
the early evening. AT KBGR, mainly VFR during the day and
evening, but with IFR possible in low cloud/fog late night and
early morning. VFR expected at all the terminals Sat.
&&
.MARINE...
NEAR TERM: No headlines will be needed over the waters through
Tuesday. The main concern will be areas of dense fog which will
reduce visibility to 1SM or less at times.
SHORT TERM: The wind and seas will remain below small craft advisory
levels through the end of the week. The biggest concern will be for
areas of locally dense fog at times until the cold front pushes
through later in the day Friday.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...VJN
Short Term...CB
Long Term...CB
Aviation...VJN/CB
Marine...VJN/CB
Area Forecast Discussion
National Weather Service Cheyenne WY
412 PM MDT Mon Jul 17 2017
.SHORT TERM...(This evening through Wednesday night)
Issued at 300 PM MDT Mon Jul 17 2017
Cold front laying along a line from Rapid City to Wright to Cody
this afternoon. Southeast surface winds out across western
Nebraska, northeastern Colorado and northwestern Kansas this
afternoon with dewpoint temperatures in the low 60s. So far,
latest SPC mesoanalysis showing surface based CAPE over the
southern Panhandle around 2000 J/KG with 1500 J/KG over the
northern Panhandle with no capping inversion. Weak upper shortwave
seen on latest water vapor in southwestern Wyoming this afternoon.
Seeing some convection forming over southwestern Wyoming to near
Rock Springs with this shortwave. So far, not a whole lot being
observed in the Cheyenne CWFA.
Latest HRRR guidance definitely showing an increase in convection
late this afternoon and into the evening hours with the approach
of the upper shortwave. Convection blossoms out across Carbon
County and spreads into Converse and Niobrara Counties this
evening. Believe the northern Panhandle stands the best chance at
seeing severe thunderstorms late this afternoon/evening as this
area closest to the northern front and is under the track of the
upper shortwave. SPC`s Marginal Risk area looks pretty good. HRRR
is also some convection developing across the southern Panhandle
after 00Z, which would have better instability, but less forcing.
Need to watching this area this evening as well.
Tuesday may be a little drier as the front looks to be south
across northern Colorado and much of the CWFA under dry northerly
flow. That begins to change Wednesday as southeasterly winds
return and increasing PWs return to eastern Wyoming and Nebraska
Panhandle. By Wednesday evening, PWs back to 1.2" across the
southern Panhandle. That boundary to the south looks to begin
shifting northward once again as a warm front which could serve as
a forcing mechanism for showers/storms to develop. Should begin
to see an increase in PoPs across the area Wednesday afternoon and
evening as this happens.
.LONG TERM...(Thursday through Monday)
Issued at 300 PM MDT Mon Jul 17 2017
Thursday...A slow moving shortwave trough aloft progged to move
northeast across our counties in the afternoon, and combined with
adequate low and mid level moisture, we expect scattered showers and
thunderstorms to develop, most numerous south of a Rawlins to Lusk
line. Temperatures a bit cooler with the additional clouds and
precipitation compared to Wednesday.
Friday...Drier zonal, west to east flow, develops, which will help
dry out the airmass and limit thunderstorm development somewhat,
mainly over the mountains.
Saturday...Zonal flow continues. With progged low and mid level
moisture, expect primarily isolated afternoon and evening showers
and thunderstorms, mainly east of I-25.
Sunday...Flow aloft becomes northwest. With the deeper moisture over
our eastern counties, that location expected to see the greatest
coverage of late day showers and thunderstorms.
Monday...Flow aloft is northwest, with low level southeast upslope
winds prevailing. Enough moisture for at least isolated showers and
thunderstorms to develop in the afternoon east of I-25. After a
cooler Saturday and Sunday, this day will be slightly warmer with
more sunshine and a moderating airmass.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 408 PM MDT Mon Jul 17 2017
Wyoming TAFS...VFR. Isolated thunderstorms near Laramie and
Cheyenne until 02Z. Gusts to 22 knots at Rawlins after 18Z
Tuesday.
Nebraska TAFS...VFR. Isolated thunderstorms until 03Z. Wind gusts
up to 22 knots after 19Z Tuesday, then winds decreasing.
&&
.FIRE WEATHER...
Issued at 300 PM MDT Mon Jul 17 2017
Daily chances for showers and thunderstorms mainly over the
mountains the next few days. Upper high pressure currently over
the 4 corners area will drift east the next few days allowing
more monsoonal moisture to mover into southeast Wyoming and
Nebraska Panhandle. Increasing chances for afternoon and evening
showers and thunderstorms each day, peaking out on Thursday where
most locations should see chances for wetting rains. The high then
shifts back west, cutting off monsoonal moisture, resulting in
decreasing chances for precipitation. Afternoon humidity through
Wednesday poor in our northern and western fire weather zones, but
winds should remain light.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...GCC
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...GCC
Area Forecast Discussion
National Weather Service Dodge City KS
646 PM CDT Mon Jul 17 2017
...Updated aviation discussion...
.SHORT TERM...(This evening through Tuesday)
Issued at 338 PM CDT Mon Jul 17 2017
A few isolated surface based storms have developed in a narrow area
of surface moisture convergence in sw NE/nc KS early this
afternoon, supporting the NMM/ARW/RAP13/HRRR. Differences going
forward arise in east/southeastward development of the convection
this evening and beyond. A slow moving shortwave exiting the
Rockies into the high plains appears to one the lift mechanism for
expansion farther southeast later this evening. The setup looks to
be marginal sever at best, with storm becoming clustered, not
exactly a great setup for large hail. HRRR is not indicating
impressive storm outflow, which it generally does in the better
convective wind setups. However a brief window of opportunity
for thunderstorms north of the highway 96 corridor exists
beginning mid evening.
The issue of heat indices/apparent temperatures will complicate the
forecast as well Tuesday and possibly in the future days as well.
The combination of mid upper 60s surface dew points and highs around
100 degrees or warmer across central Kansas may lead to heat
advisory criteria being met. Tuesday looks like average confidence
with respect to meeting the criteria and have added Trego and Ellis
counties into the headlines for Tuesday.
.LONG TERM...(Tuesday night through Monday)
Issued at 338 PM CDT Mon Jul 17 2017
Our region will be on the western periphery of the much higher
apparent temperatures/oppressive heat expected into the latter half
of the week. An excessive heat watch will be issued to the east of
our area, however we will start out with a heat advisory Tuesday and
assess the setup going forward as the confidence in our areas of KS
requiring excessive heat warnings is not as high. As of now the
blended forecast reduces the dew points each successive day,
which will have large impacts on the apparent temperature later in
the week. Overnight lows nevertheless remain very warm, in the
mid 70s through the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 646 PM CDT Mon Jul 17 2017
VFR conditions should prevail at all the southwest Kansas
terminals through this period. LLWS is expected at Garden City and
Dodge City and possibly at Liberal overnight. At Hays, there is
some potential for a thunderstorm cluster along the Nebraska
border to build south into that area around the 04z- 06z time
frame. Will carry VCTS at the terminal for now and monitor for
prevailing thunderstorm conditions if necessary.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 73 99 72 99 / 10 0 0 0
GCK 71 99 71 99 / 10 0 0 0
EHA 70 99 69 98 / 20 0 0 0
LBL 72 99 71 99 / 20 0 0 0
HYS 71 99 73 101 / 50 0 10 0
P28 73 99 73 100 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 1 PM to 7 PM CDT Tuesday for KSZ030-031.
&&
$$
SHORT TERM...Russell
LONG TERM...Russell
AVIATION...Gerard
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
325 PM MDT Mon Jul 17 2017
.SYNOPSIS...
Expect scattered thunderstorms this evening over southwestern New
Mexico, with isolated thunderstorms elsewhere. Thunderstorm
coverage will decrease on Tuesday, with improving chances late
Wednesday and Thursday. While overall the Monsoon has been
relatively lacking this summer, longer range trends suggest
improvement in the overall pattern bringing more moisture to the
area by the weekend as an area of high pressure aloft shifts to
our east.
&&
.DISCUSSION...
The subtropical ridge is stretched out from southern California to
Missouri with dual centers over far northern Arizona and SE
Kansas, separated by a weak trough over western Nebraska. Water
Vapor and RAP 200mb streamlines show an upper tropospheric low
over eastern Chihuahua and a weaker one over SE New Mexico. The
latter feature may not have initialized well with the models, but
the NAM/GFS/RAP all show an elongated PV anomaly in this area.
Convection has been slightly enhanced in this area compared to the
south-central NM lowlands, but mostly has been struggling to
survive when moving off the relatively higher terrain of the
various desert mountain ranges.
Convection started a little early in Southwest New Mexico where
moisture remains a little deeper (PWs ~1.40" per GOES-16 before
cloud cover expanded, surface dewpoints in the lower-60s). The
Gila has been pretty quiet, but water vapor imagery shows an area
of subsidence/drying aloft overhead which should drift WSW heading
into this evening.
Overall best precip coverage this evening will be in SW New
Mexico, with storms likely to spread into the Gila over the next
couple of hours. Expect Isolated coverage elsewhere, with 20
coverage for most of El Paso and Dona Ana Counties. Overall
activity should really ramp down after sunset as SW New Mexico
gets "worked over" and weaker instability is unable to keep
storms going in the central and eastern parts of the CWA.
For Tuesday, our little upper level feature shifts into the
Boot Heel Region, but low level flow becomes weak, with available
moisture diminishing, and weakening instability. The relative
focus for thunderstorms will continue to be over far SW New
Mexico, but overall activity will be down a little from today.
On Wednesday, another upper level system -- either an inverted
trough (NAM) or close upper-tropospheric low (GFS) rolls into the
area. Despite the more favorable dynamics for lift, poor low-level
moisture, and H5 temps increasing to around -4C result in weak
instability through the day. Cooler air aloft (-7C at H5) comes
in during the evening/overnight hours. Still need to watch
Wednesday closely in case moisture/instability improves or cooler
air aloft moves in a little faster. This system lingers in the
area Thursday, and should bring an increase in thunderstorm
coverage then.
Overall signs early next week point to a broader area of better
moisture aloft as the subtropical ridge shifts to the east and
upper level flow becomes southeasterly.
&&
.AVIATION...Valid 18/00Z-19/00Z...
P6SM SCT-BKN060-080 BKN-OVC200-250 through much of the period.
Scattered to numerous VRB20G35KT 1-3SM TSRA BKN020-040 west of KTCS-
KDMN line and isolated to the east. Storms will mainly occur before
04Z and again after 16Z, but isolated storms may continue through
night.
&&
.FIRE WEATHER...
Monsoon pattern in full force now with good moisture over region and
daily thunderstorm chances. Best chances for the next couple of
days will remain west of the river and mountains, but spread across
the entire area by Thursday and continuing into next week.
Temperatures will be near normal with relative humidities remaining
above 20-25 percent for the lowlands and above 35 percent in the
mountains. Winds generally east to southeast 5 to 15 mph through
the period as easterly flow deepens over region.
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 73 93 75 91 / 20 10 10 10
Sierra Blanca 68 88 70 89 / 20 10 20 20
Las Cruces 68 92 70 93 / 30 10 20 10
Alamogordo 68 92 69 93 / 20 20 20 20
Cloudcroft 50 70 51 71 / 20 30 30 30
Truth or Consequences 69 93 70 95 / 30 20 20 20
Silver City 62 84 64 89 / 40 50 40 50
Deming 68 92 70 94 / 30 10 20 20
Lordsburg 67 90 68 93 / 30 40 40 30
West El Paso Metro 72 92 75 90 / 20 10 20 10
Dell City 69 92 69 90 / 20 10 10 10
Fort Hancock 72 93 76 91 / 20 10 10 20
Loma Linda 66 85 67 84 / 20 10 20 20
Fabens 72 93 74 92 / 20 10 10 20
Santa Teresa 69 92 73 91 / 20 10 20 10
White Sands HQ 70 92 71 91 / 20 10 20 20
Jornada Range 67 92 68 94 / 30 10 20 10
Hatch 67 93 68 94 / 30 10 20 20
Columbus 69 92 70 93 / 30 10 20 20
Orogrande 70 92 72 93 / 20 10 20 20
Mayhill 54 78 55 80 / 20 30 20 20
Mescalero 54 79 56 83 / 20 30 20 20
Timberon 54 77 55 79 / 20 30 30 30
Winston 58 84 60 87 / 40 40 40 40
Hillsboro 64 88 65 93 / 30 30 30 30
Spaceport 67 92 69 94 / 30 20 20 20
Lake Roberts 54 84 53 86 / 40 60 50 50
Hurley 62 86 63 90 / 30 40 40 40
Cliff 60 88 61 94 / 40 50 40 40
Mule Creek 60 87 65 90 / 40 60 50 50
Faywood 62 86 63 90 / 30 30 30 30
Animas 67 91 69 94 / 40 30 30 30
Hachita 66 91 68 94 / 30 20 30 20
Antelope Wells 65 89 67 92 / 40 40 30 40
Cloverdale 62 83 65 87 / 40 50 40 40
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&
$$
25-Hardiman/26-Grzywacz
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
754 PM CDT Mon Jul 17 2017
.UPDATE...
Isolated to scattered showers and thunderstorms have developed late
this afternoon over the Coastal Plains into the I-35 corridor due to
a weak sea breeze and outflow boundaries. Therefore, we have added
30 POPs to areas along and northeast of a Johnson City to New
Braunfels to Gonzales line. Isolated showers and thunderstorms are
maintained for our western zones where convection developed earlier
this afternoon due to dynamic forcing from an inverted mid-to-upper
level trough moving northwest up the Rio Grande Plains. Area
soundings show weak stability at the melting layer and around 700 mb
which should limit the strength of convection, but occasional cloud
to ground lightning and locally heavy downpours up to one inch per
hour will be possible. The 23Z HRRR shows convection focused around
the Austin area (albeit delayed an hour) for the next few hours, so
we have carried rain chances until 10 PM, after which we only have 20
POPs mainly west of Highway 281 just in case any storm outflows
trigger additional convection despite strong stability behind gust
fronts. All convection should wane after Midnight with perhaps some
showers redeveloping over the Coastal Plains closer to sunrise.
Temperatures and dewpoints have been adjusted to match observational
and model trends, particularly in handling the very pleasant 70s and
80s over several of our western counties due to rain cooled air
behind this afternoon`s gust fronts. Low temperatures in the lower to
mid 70s are generally expected tonight with weak S-SE flow, but we
may see some upper 60s in the Hill Country.
&&
.PREV DISCUSSION... /ISSUED 721 PM CDT Mon Jul 17 2017/
UPDATE...
00Z Aviation Update Below.
AVIATION...
Isolated SHRAs and TSTMs will continue through sunset and then
gradually diminish. Locally gusty winds are possible with this
activity and along associated outflow boundaries. VCSH is included
in the TAFs and will have to closely monitor AUS over the next hour
for possibly VCTS. VFR conditions will persist through the evening
hours. A more unidirectional southeasterly, onshore low level flow
overnight should help to produce some pockets of MVFR ceilings
10Z-15Z. VFR conditions developing after 15Z along with isolated
SHRAs and TSTMs after 18Z, although slightly less coverage than
today.
PREV DISCUSSION... /ISSUED 251 PM CDT Mon Jul 17 2017/
SHORT TERM (Tonight through Tuesday Night)...
Main weather focus will center on the scattered showers and storms
this afternoon along with the isolated to scattered activity
expected again tomorrow. In addition, head index values will reach
into the upper 90s to low 100s both days as well outside of rain
cooled areas.
Cyclonic circulation of the inverted trough over south Texas can been
seen on visible satellite imagery as well as regional radar. Subtle
enhanced divergence aloft is projected per the RAP model over the
Hill Country and southern Edwards Plateau that is leading to greater
shower and storm coverage. some stronger storms will be capable of
gusty 40mph winds. Additional showers and storms are forming along
the sea- breeze and will likely shift into the coastal plains through
mid to late evening hours. The I-35 corridor will likely see the
least coverage as it appears to be just on the back side of the weak
inverted trough with slight negative vorticity advection occurring.
However, CAPE bouyancy near 1500-2000 J/Kg should off-set the
suppression to a degree with at least some isolated showers and a
few thunderstorms developing through afternoon peak heating. Much of
the activity will weaken through early evening. Some lingering
showers could occur across the Rio Grande Plains through late evening
as the base of the inverted shortwave trough pivots over the area.
All activity should dissipate after midnight.
Tuesday will feature one of the last better days of scattered rain
chances before decreasing chances occur through the rest of the week.
The remnant inverted shortwave trough will shift northwest across the
Coastal Plains while a cut-off upper level system swings into east
and central Texas. These features plus instability will aid in
isolated to scattered convection across the area under deep easterly
moist flow.
LONG TERM (Wednesday through Monday)...
Warmer and drier conditions expected from mid-week onward into the
weekend with Heat Index values climbing back above 100F most all
locations. A few locations should reach into the 105-108F range and
a low end head advisory may be warranted.
A strengthening H5 ridge across the central CONUS will reach its
influence south into Texas and help suppress rain chances except for
the near coastal plains due to weak sea-breeze activity. Mid and long
range models diverge by the weekend with the GFS indicating the ridge
shifting farther east to the Tennessee Valley while the ECMWF
retains the ridge and slightly shifts it back west. Have gone with a
mostly dry forecast towards the warmer and drier ECMWF solution as
the GFS shows an interesting cut-off trough retrograde solution that
seems questionable.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 75 96 76 98 76 / 30 20 10 10 -
Austin Bergstrom Intl Airport 74 95 75 98 75 / 30 20 10 10 -
New Braunfels Muni Airport 74 96 73 97 74 / 30 20 10 10 -
Burnet Muni Airport 72 94 73 95 73 / 30 20 10 10 -
Del Rio Intl Airport 75 96 75 97 75 / 20 30 10 - 10
Georgetown Muni Airport 74 95 74 97 75 / 30 20 10 10 -
Hondo Muni Airport 74 98 72 99 73 / 20 20 10 10 10
San Marcos Muni Airport 74 95 74 97 74 / 30 20 10 10 -
La Grange - Fayette Regional 75 94 75 96 75 / 30 20 10 20 -
San Antonio Intl Airport 75 96 75 98 75 / 20 20 10 10 -
Stinson Muni Airport 76 95 74 97 75 / 20 20 10 10 -
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...Runyen
Synoptic/Grids...LH
Public Service/Data Collection...Williams
Area Forecast Discussion
National Weather Service Peachtree City GA
1037 PM EDT Mon Jul 17 2017
.UPDATE...
Was another active afternoon and evening but maybe not quite as
active as previous days. Convection on the wane currently but
still enough pockets of instability to warrant continued pops into
the overnight. This will be especially true to the south where
shortwave energy will continue to move through. Other than some
minor tweaks to the diurnal curve, no additional changes planned
to ongoing forecast.
Deese
&&
.PREV DISCUSSION... /issued 835 PM EDT Mon Jul 17 2017/
PREV DISCUSSION... /issued 335 PM EDT Mon Jul 17 2017/
SHORT TERM /Tonight through Tuesday Night/...
Weak high pressure at the surface and several upper level impulses
on the periphery of the forecast area will bring a chance of showers
and thunderstorms mainly across southern and eastern portions of
forecast area. Convection currently developing in vicinity of a
weak surface boundary washing out over central GA and over portions
of west and north GA where impulses are moving through the upper
level flow. Models showing impulses shifting to the south and east
through this evening, with best coverage over central and portions
of east GA. Given the strength and proximity of the impulse over
northeast and east GA, it seems prudent to keep chance pops
continuing through the morning hours. The models all show some
drying as the upper ridge builds eastward tomorrow, and PWATs drop
under 1.5 inches, but with some instability present, will keep
slight chances across the north and low chance over southern
portions of forecast area. As for temperatures, guidance values are
close and will take a blend through the period.
Atwell
LONG TERM /Wednesday through Monday/...
No changes to the long term. High pressure builds over the
forecast area through the end of the week and low chance or slight
chance pops look okay. Upper level low developing over the
northeast Gulf may affect pops for the weekend but for now will
leave pops alone. Previous discussion is included below.
41
Previous...433 AM EDT Mon Jul 17 2017
LONG TERM /Tuesday Night through Sunday/...
Main frontal system from the short term will have weakened and
moved into south GA/N FL by Tuesday night/Wednesday morning. There
will still be some mid to lower level moisture across the region
even with drier air filtering into the state through the end of
the week. Will keep in low chance pops of convection through day
7.
With the drier air pushing into the region through the end of the
weak...temps will increase into the mid to upper 90s especially
across central GA. will have to keep a close eye on heat index
values as the weak continues.
AVIATION...
00Z UPDATE...
TSRA complex continues to move through ATL that was generated
from outflows and upper level disturbance. Gust to 39kts at the
airfield ahead of this activity but should see more tranquil
conditions into the first half of the overnight period. Still some
potential for IFR to LIFR tonight in the form of developing cigs.
HRRR has been really onto this potential as has the NAM and LAMP
but MAV continues to indicate lower potential. For now, will lower
current forecast to BKN MVFR and adjust downward as needed with
subsequent forecasts.
//ATL CONFIDENCE...00Z UPDATE...
Medium on IFR/LIFR potential.
High on remaining elements.
Deese
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 70 90 71 92 / 30 20 10 20
Atlanta 72 89 73 91 / 30 20 10 20
Blairsville 64 85 65 86 / 30 30 10 20
Cartersville 69 89 71 91 / 20 20 10 20
Columbus 72 90 74 93 / 30 20 20 20
Gainesville 70 88 71 90 / 30 20 10 20
Macon 71 90 72 93 / 40 30 20 20
Rome 70 90 71 91 / 20 20 10 20
Peachtree City 70 90 70 91 / 30 20 10 20
Vidalia 73 89 73 92 / 40 30 20 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Deese
LONG TERM....20
AVIATION...Deese
Area Forecast Discussion
National Weather Service Green Bay WI
1038 PM CDT Mon Jul 17 2017
Updated aviation portion for 06Z TAF issuance
.SYNOPSIS...
Issued at 219 PM CDT Mon Jul 17 2017
Warm and humid with periods of thunderstorms for the rest of the
work week and into the upcoming weekend.
The upper flow across the northern CONUS and southern Canada is in
the process of flattening as a trough from the Pacific progresses
eastward through the persistent ridge position over the
intermountain West. Though the lower amplitude pattern will
remain in place for pretty much the rest of the forecast period,
the medium range models have reached a consensus that the western
ridge/eastern trough pattern will re-appear next week.
A frontal boundary forecast to push southeast across the area
tomorrow is expected to stall to our south and linger there along
the southern edge of the westerlies. That will provide numerous
opportunities for precipitation, and likely lead to above (north)
to much above (south) normal amounts for the period. Warm and
humid air is expected to dominate the area. Temperatures will
probably be near to modestly above normal most of the time, though
readings will be held back on any days with widespread clouds and
precipitation.
&&
.SHORT TERM...Tonight and Tuesday
Issued at 219 PM CDT Mon Jul 17 2017
The latest RAP analysis and satellite/radar imagery show high
pressure centered over the central Great Lakes, and a cold front
positioned from northwest Minnesota to western Nebraska early this
afternoon. Skies are mostly clear across the the eastern half of
Wisconsin, though there are scattered clouds popping over western WI
in an area of greater moisture return. Looking upstream, scattered
convection is firing along the cold front over northern MN, and
mesomodels indicate a more organized complex developing later this
afternoon in this area. As the front moves southeast, thunderstorm
trends and the possibility of severe weather on Tuesday afternoon
are the main forecast concerns.
Tonight...The cold front will continue to sag southeast across the
northern Plains and into northwest Wisconsin late. Ahead of the
front, hourly high res models continue to indicate that the
thunderstorm complex over northern Minnesota will dive to the south
into the instability and miss north-central WI to the west late in
the evening into the overnight. Both the nam/arw move this complex
very close, however, to Vilas/Oneida counties, so will leave a small
chance in the forecast. Otherwise, a warm front will move east
across the region tonight and could see areas of 4-5 kft move in
with the front. Some potential for lower stratus to develop as
well, similar to this morning over western WI, but not confident in
coverage or location. Will increase sky cover some though. Warmer
lows in the upper 50s to low 60s.
Tuesday...After some patchy or scattered low clouds, the cold front
will continue to move southeast into northwest Wisconsin during the
morning and into north-central WI during the afternoon. May see a
few showers pop up in the morning ahead of the front over north-
central WI. But the main show will occur from mid-afternoon onward
as convection develops along the front from western WI to the
western U.P. Guidance depicts 1500-2000 j/kg of ml cape and 25-35
kts of deep layer shear ahead of the boundary, which would be
sufficient for severe storms. Looking at damaging winds and large
hail as the main threats, though cannot rule out an isolated spin up
given the low lcls, while 1-2 inches of rain is also possible. As
storms grow upscale, some acceleration of the line is possible late
in the afternoon, but tough to say how far east they will push by
00z. Think they could be approaching the Door and Fox Valley by this
time. Warmer and more humid, with highs ranging from near 80 in the
north to mid or upper 80s in the south.
.LONG TERM...Tuesday Night Through Monday
Issued at 219 PM CDT Mon Jul 17 2017
This pattern just does not lend itself to adding much detail to
the forecast beyond the first day or two.
The first round of storms will continue into Tuesday evening as
the front presses south across the area. The severe threat will
continue along the front through the evening, but should wane
later in the night. The steady southeast progression of the front
combined with a substantial veering of the 850 mb flow will limit
the potential for training of storms and flash flooding. But,
PWATs rising to near 2 inches suggest localized heavy rainfall
will occur, especially in the vicinity of significant storm
mergers. That could result in some flooding in urban areas where
there is a lot of pavement.
There will probably be a lull in the precipitation chances
Wednesday as the front continues south. But given the flat upper
flow, it is not surprising that the models quickly generate
return flow behind weak high pressure crossing the region. The
upper flow never seems to back enough to allow the surface
boundary to lift back through the region during the rest of the
forecast. That will likely keep the excessive rainfall/flash
flooding threat focused to our south. But there will still likely
be several rounds of showers and thunderstorms across the
forecast area as shortwaves interact with the frontal zone.
No significant chances were made the forecast initialization
generated from a broad-based blend of guidance products.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1018 PM CDT Mon Jul 17 2017
A thunderstorm complex inches closer to north-central Wisconsin
this evening, while the meso models continue to insist it will
continue to die out as it heads over north-central Wisconsin.
Despite this insistence it refuses to completely die out,
therefore will put a tempo group for some showers at RHI with this
issuance. The blowoff from the thunderstorms will probably keep
fog in check at RHI, and quite possibly AUW/CWA. However will
maintain some MVFR fog at the central Wisconsin airports given
some breaks in the cloud cover. Otherwise clouds will continue to
increase from west to east as a warm front approaches with strong
to severe storms to develop over the area during the afternoon
and evening hours.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS.......Skowronski
SHORT TERM.....MPC
LONG TERM......Skowronski
AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service Wilmington NC
953 PM EDT Mon Jul 17 2017
.SYNOPSIS...
The risk for showers will begin to diminish as a front continues
to slowly dissipate through Tuesday. A building ridge of high
pressure will bring the hottest temperatures of the summer
season late week and during the weekend. Heat Advisories or
Excessive Heat Warnings may be required later this week and
through the weekend.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 900 PM Monday...Showers have been few and far between
this eve. There was a cluster of showers and a few thunderstorms
working northward from southern South Carolina at mid eve. We
still do expect an uptick in showers through late eve and
overnight, favoring the coast over inland areas as a potent
shortwave in the mid-levels rides up the coast ahead of the
main upper trough across the western Carolinas. The upper trough
may actually close off across North Carolina late tonight and
Tue. The high resolution HRRR has been fairly consistent with
its depiction of such a scenario. Showers will be most common,
but a few rumbles of thunder are expected during the overnight
hours. Otherwise, considerable cloud cover will persist. Lows
will be in the lower to mid 70s.
Models continue to show another unsettled day Tue, but with the
arrival of drier air by/during the afternoon, the number of showers
and thunderstorms should be on a downward trend.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...Trough aloft will persist this period but in a
weakening state as it begins to lift NE. This trough will try to
close off as it moves slowly east, and mid-level ridging expands and
amplifies from the west. As this upper low closes off and ejects NE,
the heat will begin to build back into the area with highs Wednesday
climbing into the low 90s well inland, upper 80s at the coast, with
much more sunshine than experienced earlier in the week. Much drier
air noted in forecast soundings thanks to increasing W/NW flow aloft
will cap much convection, but moist soils combined with warm temps
and MLCape to 1500 J/kg will allow at last isolated showers and
tstms Wednesday. Best chance for convection will be along the sea
breeze and piedmont trough during peak heating, but expect many
places will be dry. Any convection will wane quickly after dark
Wednesday night, but mins will remain warm in the mid 70s, a few
degrees warmer than mins forecast for Tuesday night.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 300 PM Monday...A deep ridge of high pressure will build
across the southeast through the long term period, which would
indicate potential for hot weather through much of the long term
period. There is one obstacle in the forecast which could throw
off excessive heat. A cutoff low will break off from the parent
trough reaching down the southeast coast. This low has been in
the models for days now, but it was supposed to break off over
GA on Wed and now is now still showing up but off the southeast
coast on Thurs. This low will be pushed southwest as two strong
ridges build into the Carolinas. One from the central CONUS and
one from the Atlantic. This pesky upper low could throw off the
forecast a bit but overall still going with quieter weather
period due to increasing subsidence and drying aloft, as well
as an increasing westerly component to the low level flow around
the Atlantic ridge. The ridge should hold off any fronts to the
north but could see some convective debris clouds reaching down
into the area. Therefore will include potential for some higher
clouds, and some aftn cu, but left mainly silent PoPs in
forecast.
The upper low could keep heights from rising as high as
originally thought, but if this low gets squeezed south faster
and allows the ridges to build over the southeast from the west
and east, we could see h5 heights as high as 593 to 594 dm and
850 temps as high as 23c. Overall expect hot and humid weather
with high temps between 95 and 100 through much of the period,
but confidence is lower of near record or record heat with
temps reaching over 100 degrees and heat warnings.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
As of 00Z Tuesday...Showers were few and far between. We do
expect an uptick in showers overnight and Tue morning and this
may bring a period of MVFR. The risk for showers will be
highest at the coastal terminals. At KLBT and KFLO, stratus may
drop ceilings into the IFR category between 09-14z along with
some patchy MVFR BR. The risk for showers will be decreasing
through the day Tue. At this time, we have not included showers
at KFLO and KLBT after 09z and KILM/KCRE/KMYR after 15-16z.
Extended Outlook...Flight restrictions are not foreseen at this
time.
&&
.MARINE...
NEAR TERM /THROUGH TUESDAY/...
As of 900 PM Monday...A very light wind field across the waters
with no appreciable jetting should allow winds to become variable
in direction overnight. This will be facilitated by an increase
in showers and some thunderstorms. Wind speeds will be under 10
kt outside of any strong convection. Seas will be 2 to 3 ft and
largely the result of an ESE ground swell. Light wind fields
and benign seas will continue across the coastal waters on Tue
as showers and thunderstorms become fewer in number as the day
progresses.
SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...High pressure offshore will remain
dominant, but the Piedmont trough will get pushed offshore each
evening thanks to developing westerly flow aloft which will
create a wind shift at times. Winds will predominantly be SW
around 10 kt through the period, but a shift to the west is
expected each evening with a slight decrease in speeds. These
light winds, as well as the periodic offshore component, will
allow the sea state to be ground swell driven, with seas staying
2-3 ft through the period.
LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 300 PM Monday...Bermuda High regains control at the
surface with SW flow mainly 10 to 15 kt. Should see a spike in
winds each aftn into early evening enhanced by sea breeze and
lee side troughing, and winds overnight will become more
offshore due to land breeze. Expect quieter weather as ridge
builds aloft through late week. Seas will remain in the 2 to 4
ft range.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
NEAR TERM...RJD/SHK
SHORT TERM...JDW
LONG TERM...RGZ
AVIATION...RJD
Area Forecast Discussion
National Weather Service Jacksonville FL
738 PM EDT Mon Jul 17 2017
.UPDATE...Large area of showers/t-storms this afternoon gradually
winding down. Some late afternoon partial heating in our western-
most counties westward allowing a few showers to redevelop. This
may continue a few more hours in our wrn/nrn counties...and will
maintain low POP there...but believe HRRR model showing another
round of widespread showers moving over the area later this
evening is erroneous.
Latest guidance suggests there may be some delay during morning
before showers/t-storms develop and work across forecast area.
Have adjusted hourly POP/weather grids to reflect this.
Nevertheless expect another active t-storm afternoon with upper
trough over the area. With slight cooling aloft and slightly
steeper mid-level lapse rates...strong storms with hail and
strong downburst winds are anticipated.
&&
.AVIATION...Generally VFR conditions expected. Included some MVFR
fog KVQQ/KGNV...possible where significant rainfall occurred...but
SREF shows only very low MVFR/IFR probabilities. Maintained 30
PROB group TSRA in TAFs for tomorrow afternoon...likely to be
replaced with TEMPO group in later TAF issuances. Winds generally
light...but will be strong and gusty in any TSRA that form.
&&
.MARINE...Surface ridge will remain south of the area through the
week with a light southwesterly flow becoming southeasterly each
afternoon and evening due to the Atlantic sea breeze. Seas will
generally remain in the 2 to 4 foot range with winds and seas
below Small Craft Exercise Caution criteria.
Rip Currents: Lows risk through Tuesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 73 90 73 93 / 20 60 20 30
SSI 74 87 78 89 / 10 50 20 30
JAX 73 91 76 92 / 10 60 20 40
SGJ 74 88 75 89 / 20 50 20 40
GNV 72 91 73 92 / 20 60 20 60
OCF 73 90 74 92 / 20 60 20 60
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
$$
Wolf/Nelson/McGinnis
Area Forecast Discussion
National Weather Service Midland/Odessa TX
602 PM CDT Mon Jul 17 2017
.DISCUSSION...Please see 00Z Aviation discussion below.
&&
.AVIATION...Radar is indicating isolated convection across the
area. Basically it will be hit or miss showers...mostly miss. As
such...will keep them out of all TAF`s at this time but will
monitor and amend as needed. Otherwise VFR conditions will be the
rule with light southeast winds through Tuesday.
Strobin
&&
.PREV DISCUSSION... /issued 245 PM CDT Mon Jul 17 2017/
DISCUSSION...
Not many changes to the current forecast, as persistence rules. Area
radars do not look quite as busy as they did this time 24 hours ago,
absent outflow boundaries rolling down from the NE. However, a peek
at vis imagery and out the window show cu fields expanding rapidly,
and mesoanalysis indicates the cap is gone. The HRRR is a little
too quick in developing diurnal convection...especially over the
Permian Basin, while other hi-res models hold off for a couple of
hours. W/residual boundaries from yesterday`s activity still
knocking about, development later this afternoon/evening cannot be
ruled out.
Otherwise, WV imagery indicates the upper inverted trough has moved
west to srn AZ, as also noted by the dearth of activity to the SW.
However, another trough has made landfall over the Rio Grande
Valley, and is forecast to arrive in the Big Bend by about 00Z Wed.
This will further shift the upper ridge east, to the MS Valley by
around 12Z Friday, leaving West Texas and Southeast New Mexico on
the SW periphery of the ridge. This pattern should confine
convection to the western mtns into the extended, especially after
the second inverted trough clears the region. w/minimal ridge
influence, temps will remain around normal UFN.
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 71 93 72 95 / 10 10 0 10
Carlsbad 69 94 70 94 / 20 10 10 10
Dryden 73 92 73 94 / 10 20 10 10
Fort Stockton 69 91 70 93 / 10 20 10 20
Guadalupe Pass 65 83 65 84 / 40 20 10 20
Hobbs 67 91 67 91 / 20 0 0 0
Marfa 61 84 62 84 / 30 50 20 50
Midland Intl Airport 71 93 72 94 / 10 0 0 10
Odessa 71 93 72 95 / 10 0 0 10
Wink 70 94 71 96 / 10 10 0 10
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&
$$
33/12/33
Area Forecast Discussion
National Weather Service Melbourne FL
920 PM EDT Mon Jul 17 2017
.UPDATE...
Got to hand it to the local mesoscale models as both the HRRR and
WRF-ARW6 nailed the widespread and intense late afternoon-early
evening convection across the north. Several areas experienced
strong to even severe storms with hail ranging between pea and
quarter size, along with sporadic damaging wind gusty. Rainfall
accumulations were as high as 3 to 4 inches in some spots, with
KMCO/Orlando Int`l Airport setting a new daily rainfall record of
3.09" (with light rain still falling) breaking the old record of
2.47" set back in 1950.
Aside from some spotty showers and a few storms redeveloping near
the Cape and offshore Volusia/ Brevard Counties, we`re left with a
large swath of slowly diminishing debris rain over the northeastern
CWA, which should be completely dissipated by, or a little before, 11
PM. Evening update will remove mention of precip everywhere except
Volusia County and perhaps northern Brevard as well. In these areas,
it will be ended by 11 PM or midnight.
Expect overnight mins in the L-M70s. In fact many areas have already
reached the L70s due to the very heavy rain which fell, and temps in
these spots will remain steady or rise a couple of degrees overnight.
&&
.AVIATION...VFR with rain dissipating at KMCO shortly, KSFB by 02Z,
and DAB around 03Z. Looks like another convectively active day on
Tuesday, as reflected by late afternoon TEMPO groups having already
been inserted into the 00Z TAFs for the inland aerodromes.
&&
.MARINE...After convection dissipates, associated chaotic and gusty
winds will settle back to light southerly with seas 2FT near shore
and 3FT well offshore.
&&
UPDATE/AVIATION...Cristaldi
RADAR...Sedlock
IMPACT WX...Smith
&&
.PREV DISCUSSION... /issued 336 PM EDT Mon Jul 17 2017/
Tuesday...Mid level trough over the southeast states will keep
subtropical ridge suppressed to our south, which will provide a deep
layer of moist southerly winds. Precipitable water values should
start off the day around 2 inches. Sea breezes will get deep
convection going by early afternoon, with subsequent boundary
interactions producing scattered to numerous thunderstorms into late
afternoon/early evening.
MOS POPs are around 60-70 percent which is similar to our current
forecast, so little change planned. Afternoon highs should be a
couple of degrees lower than Monday given the increased cloud cover
and earlier start to showers and storms.
The more rigorous late-day boundary collisions should be able to
produce a few strong storms. Forecast soundings continue to look
supportive of strong wind gusts, with frequent lightning and very
heavy rainfall also likely.
Wednesday-Monday (Previous Discussion)...The mid-level trough over
the southeast states will shift offshore by late week, leaving a
weakness in the ridge aloft and preventing the surface high from
building back to the north. While this will maintain light
south/southwest flow through the period, decreasing moisture will
lead to gradually lowering PoPs into the weekend. PoPs peak (50-60%)
on Wednesday before chances decrease (30-40%) into the weekend.
Given the lower storm coverage, temps should warm several degrees by
late week with highs forecast into the mid 90s across the interior.
&&
.AVIATION...Scattered to numerous showers/storms are expected at
the interior terminals through evening. Some will be strong with
frequent lightning strikes, gusty winds over 40 mph and torrential
downpours. Elsewhere, there is a chance for showers or storms
until a little after sunset, then VFR through Tue morning. Very
moist atmosphere in place will bring scattered-numerous showers
and storms on Tue afternoon.
&&
.MARINE...
Tonight-Tuesday...Axis of Atlantic ridge will shift south of the
waters. This will provide south winds, except southwest in the
northern waters. Speeds still look to be 10 knots or less.
Recent nearshore buoy reports show seas below 2 feet. The long
easterly fetch region is getting shunted southward with the ridge,
so seas will likely continue 1-2 feet nearshore and might be up to
2.5 feet well offshore. Moist air in place will likely produce
scattered night/morning showers/storms and then some of the
scattered strong Tue afternoon storms over the mainland will likely
push across the coast again.
Wed-Sat...High pressure will remain south of area, leading to gentle
south to southwest winds that will become east/southeast as the sea
breeze develops each afternoon. This pattern will continue to result
in rather benign sea conditions.
The moist southerly wind flow will continue to support scattered
night/morning showers and storms through mid week before coverage
decreases some by late week. Some of the stronger afternoon storms
over land should continue to impact the coastline.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 75 90 75 90 / 30 60 30 50
MCO 75 92 75 93 / 30 70 20 60
MLB 76 91 76 90 / 30 60 30 50
VRB 75 90 75 90 / 30 60 30 50
LEE 76 92 76 93 / 30 60 20 60
SFB 75 92 75 93 / 30 60 20 60
ORL 76 92 76 93 / 30 70 20 60
FPR 74 91 75 90 / 30 60 30 50
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
Area Forecast Discussion
National Weather Service New York NY
1059 PM EDT Mon Jul 17 2017
.SYNOPSIS...
A weak trough remains nearly stationary over the region through
Thursday. A cold front passes Friday, followed briefly by high
pressure Saturday. A warm front approaches Sunday, and low
pressure impacts the area early next week.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Convection has dissipated across the region. However, both the
upper and surface troughs move into the area overnight. Some of
the high res models, in particular the 3km NAM, fires up
convection across the Lower Hudson Valley and southern CT. The
HRRR on the other hand is quiet, but has also done poorly with
over forecasting convection over NE PA. Have decided to keep
low chances overnight with moderate to high instability in
place.
The other forecast challenge will be any fog/stratus
development overnight. Typically, in the warm season, dense fog
is not a problem. The greatest chance for fog development will
be across eastern CT and far eastern Long Island, with patchy
fog possible everywhere outside of the city.
Low temperatures will be several degrees above normal.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Although the short wave will move east of the area by Tuesday, a
secondary upper low to the southwest and the stalled frontal
boundary will likely provide focus for at least isolated showers
and thunderstorms through Tuesday night, with the greatest
potential north and west of the city. High temperatures will be
close to normal, while lows will once again be near to slightly
above climatological normals with humid conditions lingering.
The potential for fog to redevelop will need to be monitored.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Unsettled weather expected through much of this time frame.
Lingering weak trough aloft, along with sfc trough should result in
a few showers or thunderstorms Wednesday.
Thereafter, the weak upper trough just to our south makes slow
progress east Wednesday night and Thursday, with gradually lowering
heights over the northeast late in the week and through the weekend
as larger upstream trough tracks east. A surface cold front ahead of
these lowering heights slowly moves through Friday.
Cannot rule out an isolated shower or thunderstorm during this time
frame, although drier air in NW flow Friday should result in
predominately dry conditions.
Thereafter, the weekend forecast remains in question due to
differences in handling potential MCS riding along a warm front. At
this time, feel Saturday remains dry, although latest ECMWF and
Canadian solutions suggest otherwise. Hard to pinpoint these
complexes this far out, and will maintain higher probabilities for
the latter portion of the weekend as the main low, and front
approach.
Unsettled weather continues into Monday as a cold front slowly
pushes through.
Temperatures Wednesday and Thursday look warm, with above normal
readings anticipated. By the weekend, the lowering heights should
result in closer to normal temps. Potential showers/tstms will also
impact temps if they do indeed occur this weekend across the area.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
A weak front remains nearly stationary over the region through
Thursday.
VFR through the period at the city terminals. However, there is
a possibility that fog does develop overnight, bringing vsby
down to MVFR conditions. Confidence is not high enough to
mention in the TAFS.
Outside of the city, expecting MVFR ceilings and visibilities to
develop from east to west, beginning around 06Z. The lowest
conditions are expected to be at KGON overnight, where IFR cigs
and visibilities are possible. VFR conditions then return
Tuesday morning as any fog and/or low clouds lift.
Southerly flow will become light and variable outside of the
city overnight. Winds then return out of the south Tuesday
afternoon at 10 kt or less.
.OUTLOOK FOR 00Z TUESDAY THROUGH SATURDAY...
.Tuesday-Thursday...Chance of showers and thunderstorms,
primarily in the late afternoon and from NYC north and west.
.Friday-Saturday...VFR.
&&
.MARINE...
A very weak pressure gradient over the region will limit winds
to 10 kt or less, and keep seas well below SCA levels through
Saturday.
Any thunderstorms that move across the area waters may produce
brief SCA to possibly gale conditions.
&&
.HYDROLOGY...
There is a low chance for heavy rain/flooding this weekend
ahead of a frontal system.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...MD/PW
NEAR TERM...MD/DW
SHORT TERM...MD
LONG TERM...PW
AVIATION...CB
MARINE...MD/PW
HYDROLOGY...MD/PW
Area Forecast Discussion
National Weather Service Blacksburg VA
913 PM EDT Mon Jul 17 2017
.SYNOPSIS...
A weak front across southern sections of the region will linger
near the Blue Ridge overnight into Tuesday before dissipating.
A residual upper trough should also remain in place east of the
mountains later Tuesday into Wednesday. High pressure will then
return warmer and more humid weather by late in the week.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 855 PM EDT Monday...
Widely scattered pulse convection has faded for the most part
but still have areas espcly near the Blue Ridge and foothills
that have not been worked over per lingering instability. In
addition decent vort/wave aloft to cross the region overnight as
a broad upper trough drifts east over top the residual surface
boundary across southern sections. This combined with less cap
aloft and a wetter boundary layer could lead to a few added
shra/tsra through about midnight before loss of heating wins
out. Latest short term guidance quite inconsistent with where or
if any lingering convection will take shape, with most
convection very slow moving and outflow driven given chaotic
light winds aloft off evening soundings. Therefore will leave in
some isolated pop mention mainly south-east over the new few
hours with more clouds near the front over the southeast per
latest satellite and lingering strato-cu northwest. Expect with
some overnight clearing to again see fog development espcly
where earlier heavy rainfall occurred and across the western
mountain valleys. Left temps similar to previous with overall
lows in the 60s.
Previous discussion as of 326 PM EDT Monday...
Regional radar mosaic as of 3:00 pm this afternoon shows
scattered, slow-moving strong thunderstorms from just west of
Galax southwestward into the NC mountains. More isolated,
garden-variety storms were also developing in the central VA
Piedmont. One storm has pulsed to radar-indicated severe limits
in Grayson County this afternoon. Convection has formed in a
moderately unstable environment along moisture convergence zone
and aided by upper support from vorticity lobe currently
spiraling near Knoxville. Lapse rates in mid-levels being on the
steep side and freezing levels being around 12,000 ft
AGL...though deep- layer wind shear values only support pulse
convection. Strongest pulse storms would be capable of gusty
winds and small hail, with pea- size hail having recently been
reported near Boone. Still at least isolated storms possible
along the northern Blue Ridge up into the southern Shenandoah
Valley, but more nebulous forcing may keep coverage more
isolated. These trends generally reflected in recent runs of the
HRRR and 3-km NAM, which show decreasing convective coverage
and strength toward 9 pm. Aforementioned mid-level vort/trough
digs into the central NC Piedmont, with daytime cu clouds
diminishing. Winds tonight become extremely light through the
entire column tonight which may lead to a patchy fog/stratus
development later in the overnight. Patchy fog also possible in
the western river valleys and in areas where it has rained.
Overall similar lows to last night in the upper 50s to upper 60s
areawide, coolest west and milder/muggier east and south.
For Tuesday...any overnight fog should burn off with partly sunny
skies. Skies should fill in with cumulus readily associated with
cold pocket of air aloft (-12C at 500 mb). Related mid-level trough
should be slowly moving eastward into coastal NC through the
daylight hours, leaving the forecast area on the northern side of
the trough. Thus it appears forcing likely to be being even more
limited than today. Though the 12z/17th GFS and ECMWF solutions try
to paint much of the forecast area with some light QPF, it`s not
clear if the coverage will be that widespread. Differential heating
along the terrain may be the only substantive source of lift.
Started with the global model PoPs but also blended some of the
available mesoscale models to show the spatial coverage variation.
Namely: isolated/slight chance PoPs for the VA/upper NC Piedmont and
in southeastern WV, scattered/chance PoPs along the Blue Ridge. As
the case today, storms should be slow moving in a weak shear
environment, but weaker lapse rates should keep thunderstorms more
general/garden-variety. Highs in the upper 70s/mid 80s mtns with low
90s confined to the Piedmont.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 326 PM EDT Monday...
You can expect an increase in temperatures this period as the axis
of the upper trough moves from the piedmont of VA/NC east to the
Atlantic coast. 5h heights will stay mainly in the 591 DM range,
while 8h temps rise from +18C to +20-22C. At the sfc, high pressure
is going to be in place over the southern Appalachians, with lee
trough in the piedmont. Weak convergence along the Blue Ridge and
differential heating may lead to isolate to widely scattered storms
Wednesday afternoon/evening. Appears subsidence behind the trough
may limit coverage.
More subsidence/drying aloft will keep any convection at bay
Thursday so expect a mostly sunny/hot day, with highs in the mid 80s
to near 90 mountains, to lower to mid 90s foothills/piedmont. Heat
indices should not be an issue as dewpoints will be in the lower to
mid 60s.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 325 PM EDT Sunday...
Keeping the theme of hot and humid with daily threat of storms. Will
be on the northern periphery of upper high, so any convection on the
southern belt of the westerlies may scrape our area in the Fri-Sun
time frame. Models diverge Monday with new ECMWF showing a trough
digging through the Ohio Valley which is more favorable for
convection. The GFS showing less amplification with better ridge
over the southeast. With this being 7 days out will keep token low
chance pops in mainly west.
Saturday-Sunday appear to be hottest days with 8h temps around +24C.
Looking at upper 80s to around 90 west, to mid to upper 90s east.
Convection and any upstream blowoff of high clouds may inhibit this
though.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
As of 700 PM EDT Monday...
Convection remains isolated to widely scattered across
southern/eastern sections early this evening and will likely
linger mainly around KLYH another hour or two before fading. May
also see added isolated shra/tsra pop up due to outflow until
shortly after sunset when instability should finally diminish.
Thus keeping in a VCSH or VCTS mention where convection
continues to linger while basically leaving out elsewhere for
now into the evening. As an upper level trough swings into
central NC tonight, light winds and clearing skies should allow
for development of IFR or lower fog/stratus in the river
valleys including KLWB/KBCB, with another area of development
possible in the piedmont where have seen pockets of heavier
rainfall this afternoon/evening.
For Tuesday, anticipate any fog from the overnight to burn off
with sunshine. Should see deepening VFR cumulus, but potential
for showers or thunderstorms mainly after 18z/2pm Tuesday.
However isolated coverage and short lived extent of any
convection makes things too uncertain in include any mention in
any of the terminals. Winds light and variable.
Aviation Extended Discussion...
Increasingly diurnal nature to any convection as we progress
into the middle and later part of the week should make for
mainly VFR excluding any late night sub-VFR fog/stratus. An
upper ridge across the Midwest will slowly build east- southeast
through the period. No organized convection expected through
this time frame, perhaps toward the weekend in the form of an
MCS from the upper Midwest/Ohio Valley. Confidence is this
occurring is low to medium at this point.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...JH
NEAR TERM...AL/JH
SHORT TERM...WP
LONG TERM...WP
AVIATION...AL/JH/RAB