Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/06/20
Area Forecast Discussion...Updated
National Weather Service Billings MT
808 PM MDT Wed Aug 5 2020
.UPDATE...
Much of the shower and thunderstorm activity over the
Beartooth/Absaroka/Bighorn Mountains and adjacent foothills has
dissipated. An isolated shower or thunderstorm is still possible
over these areas this evening with a weak shortwave moving
overhead. Current forecast has this handled well. Otherwise just
made some adjustments to hourly temperature, relative humidity and
cloud cover toward latest short-term model data. Rest of forecast
is on track.
Some smoke may be noticeable from central Rosebud County
west/northwestward to Musselshell and northeastern Yellowstone
Counties this evening as a fire burning in southwestern Custer
County produces smoke that is then moved by ESE winds. HRRR model
has this smoke plume very narrow and dissipating by midnight MDT
so left it out of the forecast for now. RMS
&&
.DISCUSSION...
Tonight through Friday night...
High pressure was building over the region today with some weak
energy and moisture moving through the west side of the ridge.
This was producing a few showers and thunderstorms over the higher
terrain and adjacent foothills. With weak shear, most storms will
be confined to the higher terrain, although a few could slide off
onto the lower elevations over the west this evening.
High pressure begins to shift east on Thursday as an upper trough
moves into the Pacific Northwest. Temperatures will warm into the
mid 90s for many places with afternoon humidities in the 20s with
easterly low level flow in place. Shortwave energy and monsoonal
moisture advecting into the area from the southwest will produce
showers and thunderstorms. Convection will develop over the higher
terrain Thursday afternoon and lift northeast through the area
during the evening. Soundings showing inverted V signature, so
strong winds will be the primary threat. Enough cape around for
the possibility of hail, but limited shear and warm mid levels,
should keep hail size from getting too large. Increasing lightning
activity will pose a concern for fire starts but precipitable
water values near an inch over the eastern half of the area will
translate to locally heavy rain.
A cold front will push into the area early Friday morning. This
will provide cooler temperatures for Friday and a slight chance of
a shower or thunderstorm in the afternoon and evening. The chance
of convection again looks to be confined to the higher terrain
and over southern locations, to the north of the frontal boundary
that will be slowing pushing through northeast Wyoming during the
day. High temperatures will fall from the mid 90s of Thursday, to
the upper 80s on Friday, which is right around the seasonal norm.
TWH
Saturday through Wednesday...
Drier air will surge into much of southeast Montana Saturday, but
there will be a brief period of theta-e return in our far east,
associated with another approaching shortwave, and this may yield
a few late day t-storms east of Miles City and Broadus.
Confidence is high among ensembles that we will see a drier air
mass underneath zonal flow Sunday through Monday, with the
northern Rockies ridge being suppressed by a trough over Alberta/
Saskatchewan. There remains differences among models in the amount
of cooling we may see this far south, but the ensemble consensus
is in line with the operational EC in keeping us warmer than the
GFS on these days. Overall, expect near to slightly above normal
temps with dry conditions.
Ridge should start to rebuild by next Tuesday, and this looks
like a warmer and still mainly dry day, with possible late day
storms over the mountains. Deepening low over the Pacific
Northwest will allow for southwest flow and increasing
thunderstorm chances next Wednesday and Thursday, along with
continued warm temperatures.
Regarding fire weather, overall theme from Saturday and beyond is
for afternoon humidity in the teens becoming more common, with
poorer nighttime recovery. More typical late summer fire weather
conditions as we move into mid August. JKL/TWH
&&
.AVIATION...
VFR will prevail through the TAF period. Isolated showers and
thunderstorms are possible this evening west of KHWQ-KBIL-KSHR.
Scattered showers and thunderstorms are expected over southern MT
and northern WY Thursday afternoon into the evening. Storms
Thursday could produce strong, gusty winds and small hail. RMS
&&
.PRELIMINARY POINT TEMP/POPS...
Thu Fri Sat Sun Mon Tue Wed
-----------------------------------------------------------
BIL 062/095 064/088 058/089 059/087 058/087 057/089 060/092
12/T 21/U 10/U 00/U 10/U 01/U 12/T
LVM 054/093 054/086 049/088 051/087 051/087 051/089 053/090
24/T 22/T 10/U 01/U 11/U 01/U 12/T
HDN 061/097 062/089 056/091 058/087 056/087 056/091 058/094
02/T 21/U 10/U 00/U 10/U 01/U 11/U
MLS 061/096 065/088 057/090 060/085 057/085 056/089 060/092
02/T 30/U 11/U 10/U 10/U 01/U 11/U
4BQ 060/095 063/089 058/090 060/086 057/087 056/089 059/092
02/T 31/U 21/U 10/U 10/U 11/U 11/U
BHK 054/092 062/090 055/088 058/085 054/085 052/086 057/090
01/U 31/U 12/T 21/U 11/U 11/U 11/U
SHR 057/095 059/089 055/092 056/088 054/087 054/090 056/092
13/T 22/T 21/U 10/U 11/U 11/U 12/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Fire Weather Watch in effect from Friday afternoon through
Friday evening FOR ZONE 117.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion...CORRECTED
National Weather Service Charleston SC
912 PM EDT Wed Aug 5 2020
.SYNOPSIS...
A stationary front will remain over the area through the
weekend. Atlantic high pressure will then linger off the coast
through early next week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
A relatively concentrated cluster of showers/tstms extending
from Portal and Pulaski east to Egypt and Stilson at 07/01z is
slowly working east and southeast along an increasingly ill-
defined outflow boundary. This convection is being fed by
lingering unstable conditions in the Ludowici-Savannah region
where MLCAPEs are still averaging 2500-3000 J/kg per latest SPC
instability progs. Expect this activity to keep propagating to the
east/southeast over the next few hours along a small northwest-
southeast oriented H8 theta-e ridge axis that is directed into the
Savannah Metro Area per latest RAP analysis. Increased pops to
60-70% in this region through midnight.
Later tonight, channeled shortwave energy passing through aloft
could act to spark additional mostly isolated showers/tstms
during the early morning with the better chances occurring along
the southern South Carolina coast. Adjusted pops slightly to
reflect this trend. Lows will range from the lower 70s well
inland to the lower 80s and Downtown Charleston.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
A mid-level trough will encompass the Great Lakes Region and
then shift to the east southeast, encompassing much of the
Atlantic Northeast and Southeast through Saturday. As a
stationary front remains over the area, moisture will be
plentiful and is expected to linger with PWATS around 1.75 to
2.25 inches. Isolated to scattered showers/thunderstorms are
expected each afternoon with plentiful instability and along the
sea breeze. Overall, any thunderstorms that form are expected
to diminish after sunset with the loss of daytime heating.
Temperatures will remain near normal and as of now, maximum heat
indices are expected to be between 98 and 106 degrees.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
There isn`t much change to the weather pattern expected early next
week with the continuation of near to above normal POPs and
temperatures near normal.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
VFR. An outflow boundary north of KSAV could spark an isolated
tstm near the terminal through 03z, so this will need to be
watched. Guidance suggests scattered showers/tstms will develop
near or just west of the terminals Thursday, initially near
KSAV then near KCHS. Will carry VCTS 14-19z at KSAV, but hold
off on any mention KCHS since it appears better rain chances
will remain just to the west.
Extended Aviation Outlook: Brief flight restrictions are possible
due to showers/thunderstorms, mainly each afternoon and evening.
&&
.MARINE...
Tonight: South winds less than 15 kt will prevail with seas 2-4
ft.
Thursday through Monday: Overall, winds will remain generally
south. Winds are expected to remain below Small Craft Advisory
but could become gusty up to 15 kts along the sea breeze each
afternoon and during the nocturnal surge.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
Area Forecast Discussion
National Weather Service Cheyenne WY
555 PM MDT Wed Aug 5 2020
.SHORT TERM...(This evening through Thursday)
Issued at 330 PM MDT Wed Aug 5 2020
Forecast challenges transitioning from severe thunderstorms this
afternoon...to critical fire weather conditions through the
remainder of the week.
Currently...Trough of low pressure extends along the front range
of eastern Colorado northwestward into Laramie and eventually to
near Riverton this afternoon. Radar has begun to blossom on radar
this afternoon...similar to what the short range guidance has been
showing. Probably better today than over the past several days.
Less shear today and a little more stable over yesterday. RAP
analysis showing SB CAPE of around 1800 J/KG down here near
Cheyenne to around 1000 J/KG up near Douglas. Off to the west over
Carbon County...very dry conditions being observed with Tds in the
low 20s. Red Flag Warnings look to be panning out out that way and
will continue the current afternoon RFWs for today.
Short range guidance showing storms moving out into the Panhandle
towards 00Z. Should we get this rainfall this evening...do believe
we stand a good chance at patchy fog with southeasterly upslope
flow. Did add patchy fog into the forecast for the Panhandle below
4500 feet elevations. SREF hinting at lower conditions out there
towards 12Z as well.
Drier and breezier Thursday with low humidity spreads east. Looks
like surface boundary shifts east to near the Wyoming/Nebraska
state line. GFS 700mb winds west of the Laramie Range
25-30kts...so critical fire weather conditions look to be certain
out west. Continued the Red Flag Warnings for FWZ 303 through 308.
Best chances for any afternoon showers/storms look to be east of
the Laramie Range.
Very dry conditions Friday as westerly winds continue. 850mb
humidity in the Panhandle falls to 12 percent. Did issue a Fire
Weather Watch for zones we currently have in warnings for Friday.
Later shifts may need to add the Summit and points east as we get
closer to Friday.
.LONG TERM...(Saturday through Tuesday)
Issued at 318 AM MDT Wed Aug 5 2020
A broad upper high will hold over much of the southern half of the
country through the period with the westerlies and embedded
shortwaves being lifted to the north along the international
border. Overall this will provide mainly dry and warm weather to
the CWA with just isolated convection possible where weak
shortwaves clip the CWA, right now looking like later Saturday and
again Tuesday. Temperatures will be above seasonal averages with
little day-to-day changes.
&&
.AVIATION...(For the 00Z TAFS through Thursday afternoon)
Issued at 555 PM MDT Wed Aug 5 2020
Widely scattered thunderstorms across the eastern plains of Wyoming
and western Nebraska will gradually diminish in intensity this
evening through 02z, especially for KSNY and KBFF this evening. Will
have to watch for fog or low CIGS tonight in areas that received
decent rainfall across the panhandle of Nebraska. Will keep out of
TAF for now.
HAZARDS/WEATHER TRENDS: Brief MVFR VIS in any thunderstorm activity
this evening until 02z or 03z, then VFR for the rest of tonight and
into early Thursday morning. Low confidence for fog and low stratus
late tonight for the western Nebraska terminals.
&&
.FIRE WEATHER...
Issued at 330 PM MDT Wed Aug 5 2020
Critical fire weather conditions ongoing this afternoon across
Carbon County where Red Flag Warnings are in effect through 8 PM
this evening. Dry/Breezy conditions return Thursday for areas west
of the Laramie Range. Red Flag Warnings in effect for FWZ 303
through 308 Thursday. Conditions expected to continue into Friday
with a Fire Weather Watch in effect Friday afternoon. See a
slight reprieve Friday night into Saturday as a cold front moves
into central Wyoming. This will be short lived though as
breezy/dry conditions return Sunday.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning until 8 PM MDT this evening for WYZ303>307.
Red Flag Warning from 11 AM to 8 PM MDT Thursday for WYZ303>308.
Fire Weather Watch from Friday morning through Friday evening
for WYZ303>308.
NE...None.
&&
$$
SHORT TERM...GCC
LONG TERM...RE
AVIATION...TJT
FIRE WEATHER...GCC
Area Forecast Discussion
National Weather Service Dodge City KS
640 PM CDT Wed Aug 5 2020
...Updated aviation discussion...
.SHORT TERM...(This afternoon through Thursday night)
Issued at 1200 PM CDT Wed Aug 5 2020
After yet another MCS last night, the sky had cleared completely
as of midday, with only a few lingering patches of dissolving
stratus. A beautiful afternoon will be enjoyed, particularly
considering how hot it can be this time of year, with sunshine,
lighter SE winds, and temperatures continuing well below normal.
All zones will be dry through at least 7 pm.
Yet another MCS is expected tonight, though this time models are
in agreement the most organized complex will be focused on NW
Kansas (WFO Goodland`s CWA) this evening. CAMs show this complex,
or a weakening version of it, arriving across the northern zones
(particularly I-70 corridor) by around midnight. 12z NAM/GFS and
HRRR all grab onto another shortwave embedded in the NWly flow
aloft, and generate scattered convection further south into SW
Kansas tonight. Enough evidence to nudge up pop grids to 50% for
most zones, and may need to be increased further. Severe weather
is not expected, but can`t rule out some wind gusts to near 50 mph
and/or small hail. With continued moist light SEly boundary layer
flow, short term model consensus is to develop widespread stratus
late tonight and Thursday morning (most likely in areas with wet
soils/recent rainfall). Temperatures sunrise Thursday a few
degrees warmer than recently, in the lower to mid 60s.
After morning convection wraps up early Thursday in the SE zones,
the daylight hours will be dry and warmer. Afternoon temperatures
will warm well into the 80s, with lower 90s adjacent to Oklahoma.
Light SE winds will continue. Convection chances will wane
significantly Thursday evening, with most locations remaining dry.
Rising heights and lack of focusing mechanisms are expected to
end the MCS parade Thursday night.
.LONG TERM...(Friday through Wednesday)
Issued at 151 PM CDT Wed Aug 5 2020
Traditional hot and dry August weather will return during this
period, courtesy of a dome of high pressure aloft expanding its
influence across the plains. The heat will return quite noticeably
Friday afternoon, with all locations reaching the upper 90s, with
a few locales (Oklahoma border/Red Hills) eclipsing 100. Moist
soils and green vegetation from recent rainfall will work against
the heatwave, at least for a few days, keeping triple digit
readings relatively limited. Expect no changes over the weekend,
with upper 90s common each afternoon. Morning sunrise temperatures
will also be much warmer, commonly in the lower 70s. Winds will be
S/SW and relatively light through the weekend. All grids are dry
for all zones Friday through Sunday. Starting around Monday,
12z ECMWF suggests a more interesting NWly flow pattern will
evolve. As the upper high retrogrades to near El Paso Monday
evening, the synoptic pattern will likely favor MCS generation
across/near Kansas again early next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 640 PM CDT Wed Aug 5 2020
Thunderstorms in eastern Colorado this evening are expected to
move out into western Kansas again overnight, weakening in the
process. Latest short term model trends continue to show the Hays
and Garden City terminals to be the most favorable locations for
any impacts. Stratus development still looks like a possibility
later tonight into Thursday morning and have maintained at least
MVFR cigs at most locations to reflect this.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 65 88 68 98 / 50 10 10 0
GCK 63 90 66 95 / 50 0 10 0
EHA 64 92 67 98 / 30 10 20 0
LBL 65 94 67 100 / 50 10 10 0
HYS 64 85 68 94 / 50 10 10 0
P28 67 90 70 97 / 40 30 10 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Turner
LONG TERM...Turner
AVIATION...Gerard
Area Forecast Discussion
National Weather Service Huntsville AL
749 PM CDT Wed Aug 5 2020
.NEAR TERM...(Tonight)
Issued at 749 PM CDT Wed Aug 5 2020
A small cluster of showers and thunderstorms was entering Marshall
and far northeast Cullman County. This was along a weak area of
convergence along the frontal boundary that was sitting near or just
northwest of the I-59 corridor. Dew points were around 70F along
this boundary, and the 00Z BMX sounding indicated an SBCAPE of around
2k J/kg. Successive HRRR runs have maintained some convective
activity along and east of I-65 this evening, if not later. For now,
will extend PoPs thru 06Z in this corridor along the boundary.
.SHORT TERM...(Thursday through Friday)
Issued at 251 PM CDT Wed Aug 5 2020
That low-level boundary will remain stationary Thursday, and should
continue to focus scattered showers/storms over NE AL again tomorrow
afternoon. The mid-level drying seen today may moderate somewhat
tomorrow, but PWats should still remain below normal, and that may
still reduce precip coverage slightly. The impact of all this means
that tomorrow should be very similar to today, with highs topping out
near 90.
Some very minor moisture recovery is possible Friday, but the baggy mid-
level trough axis in place over the area will finally slide east,
placing the area in a relatively drier NW flow. Much of the model/
ensemble guidance keeps the region completely dry for Friday,
although a few rogue showers could crop up near the Georgia border.
With fewer clouds/showers, temperatures should reach the lower 90s
more readily, and it is possible that blended guidance is too low.
.LONG TERM...(Friday night through Tuesday)
Issued at 251 PM CDT Wed Aug 5 2020
The weak upper level trough positioned to our northeast will lift up
and out of the east coast as we approach the weekend. A trough
building into the Pacific NW will help push a ridge into the TN
Valley, and its influence will lead to decreasing rain chances and
increasing temperatures as we round out the week. Diurnal convection
is expected to return this weekend, and thanks to a surge of
moisture associated with a lingering warm front, heat indices will
once again trend towards 100 degrees. As the Pacific NW trough
pushes eastward early next week, weaknesses begin to develop in the
governing ridge. This coupled with the push of the stalled front
northward into the TN valley and shortwave disturbances traversing
the ridge will lead to increased chances for the development of
scattered showers and thunderstorms. Despite the likelihood of
convective development, temperatures will remain seasonable in the
lower 90s during the day and low 70s at night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 514 PM CDT Wed Aug 5 2020
VFR flight weather conditions are forecast during the period. The
exception could be patchy BR/FG early Thursday morning, but have left
out of the TAFs. Also, isolated SHRA or TSRA are possible Thursday
afternoon, mainly east of the KHSV area.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&
$$
NEAR TERM...17
SHORT TERM...BCC
LONG TERM...LH
AVIATION...17
For more information please visit our website
at weather.gov/huntsville.
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
900 PM EDT Wed Aug 5 2020
.SYNOPSIS...
Surface high pressure over the western Ohio Valley will
provide mostly dry conditions and unseasonably mild
temperatures through the end of the workweek. Warmer and more
humid air will this weekend, with increased chances for
precipitation by early next week.
&&
.NEAR TERM /THROUGH THURSDAY/...
Surface high pressure is currently centered over the southern
Great Lakes, extending into the northern Ohio Valley. A
relatively dry air mass is in place -- with dewpoints generally
in the 50s. Dewpoints are in the 60s in parts of the far
southern / southeastern CWA. Overall, the forecast appears to be
largely on track, with one minor change for the southeastern
ILN CWA. The HRRR has been very consistent in producing a band
of developmental showers in the 06Z-12Z time frame, with some
support from the RAP as well. This largely appears to be a
result of mid-level forcing, with some weak ascent and moisture
advection ahead of a 500mb wave. It is entirely possible that
some precipitation may develop, but fail to reach the ground
due to the dry air in the low levels of the atmosphere.
Nonetheless, there is enough evidence in the models for a 20-PoP
(which still suggests a lack of measurable precipitation as the
most likely scenario).
The dry air near the surface will also limit the potential for
river valley fog, so this has been kept out of the grids.
Min temps were reduced by about a degree CWA-wide based on
current trends.
Previous discussion >
High pressure centered over the lower great lakes/western Ohio
Valley and overall northwest flow will keep cool and dry
conditions through tonight. Diurnal clouds will slowly dissipate
this evening, and the thick cirrus currently lifting through
the region will also lift north of the area. While an upper
level disturbance will pivot into the region late tonight, very
dry low levels will keep dry conditions overnight.
Overnight lows will moderate slightly from last night, ranging
from the lower/mid 50s north to lower 60s in the southeast where
increasing clouds expected. Light and shallow valley fog is
possible in areas outside of the increasing clouds in the
southeast.
&&
.SHORT TERM /THURSDAY NIGHT/...
Weak instability coincident with a mid level trough will advect
in a little more substantial low level moisture in the southeast
forecast area late tonight and during the day Thursday.
This will be on the southeast edge of the surface high and
will bring a very slight potential for afternoon convection
near Portsmouth/Vanceburg Thursday afternoon. Confidence fairly
low, but with some potential in the CAMs, it can`t be ruled out
so continued the mention of a stray shower.
Across the north, a shallow mid level trough and associated
will continue to pivot through the area, but dry low levels will
keep any precip chances at bay.
Highs slightly warmer on Thursday into the upper 70s and lower
80s area- wide.
For Thursday night, the moisture associated with the weak
shortwave in the SE will pivot northeast of the area, and while
surface flow remains northerly, upper level flow becoming a bit
more westerly/southwesterly. Moisture and temperatures will
begin slowly trending to more seasonable conditions.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Period begins with a H5 shortwave trof over the Great Lakes. Under
this upper trof is located high pressure at the surface. The trof
will slide into the Appalachians by Friday evening. The low levels
look pretty dry, so despite some upper support it is looking like
Friday will be dry. Highs will be close to normal ranging from the
lower 80s in West Central Ohio and the Whitewater Valley to the
upper 80s in the lower Scioto Valley.
With the H5 trof moving off the east coast Friday night, an upper
ridge in the middle of the country builds a little into the Ohio
Valley. Some northwest flow is still apparent over the Great Lakes.
The surface high will still bring dry conditions on Saturday and
highs 85 to 90 degrees.
By Sunday, a stronger H5 s/w will be working east across the
northern U.S./Canadian plains. In addition, southerly surface flow
will start the moisture return into the region. Can`t rule out some
convection popping up, so carried slight chance PoPs for all but the
far east. Highs will increase a little more, ranging from the mid
80s in the West Central Ohio to the lower 90s in the lower Scioto
Valley/northeast Kentucky.
A cold front associated with the H5 s/w is forecast to push into the
western Great Lakes on Monday. This will add surface forcing and
should help with scattered thunderstorm development. Highs will
remain above normal.
For Tuesday and Wednesday the region will be on the southern edge of
zonal flow over the Great Lakes. This will allow some upper level
forcing to affect the region both Tuesday and Wednesday, which will
prompt diurnal convective development. Above normal highs in the mid
80s to lower 90s are forecast.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
VFR conditions are expected through the TAF period. Cumulus
clouds will dissipate in the next few hours, leaving just some
cirrus overnight, along with light NNE winds. Although some MVFR
visibilities are possible at KLUK, the air mass is very dry, and
significant issues with fog are not expected.
Tomorrow, diurnal cumulus (SCT/BKN) should develop again, along
with NE winds that will likely remain below 10 knots.
OUTLOOK...Thunderstorms are possible on Monday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...JDR
NEAR TERM...JDR/Hatzos
SHORT TERM...JDR
LONG TERM...Sites
AVIATION...Hatzos
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1109 PM EDT Wed Aug 5 2020
.UPDATE...
Issued at 1108 PM EDT WED AUG 5 2020
Showers lingered over southeast KY late this evening, and a slight
POP has been extended there later into the night. After this is
finished, the HRRR and new 00Z NAM contain additional development
overnight or toward dawn over middle of the forecast area. Do not
have confidence to jump on this just yet, but if hints of it are
seen, a quick update may be required during the night.
UPDATE Issued at 815 PM EDT WED AUG 5 2020
Isolated showers over the southern portion of the area were on
the decline early this evening. The forecast was largely on track,
and only minor changes were made in blending early evening obs
into the forecast.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 410 PM EDT WED AUG 5 2020
19z sfc analysis shows high pressure moving deeper into the Ohio
Valley. This has provided a partly sunny day for the area - once
the fog burned off this morning. It also kept the convection at
bay until just recently as a few cells have popped in our far
southeast. Additionally, temperatures were a relatively pleasant
upper 70s to low 80s out there at peak heating while dewpoints
held generally in the low to mid 60s amid light north winds.
The models are in excellent agreement aloft through the short term
portion of the forecast. They all depict the main upper trough to
our north gradually lifting out of the Great Lakes tonight. In
its wake, another height minima rolls into the Ohio Valley on
Thursday along with some accompanying energy grazing northern
parts of eastern Kentucky late in the day. Given the limited model
spread with these features have favored the blended NBM solution
with a healthy lean on the CAMs for PoP and QPF details.
Sensible weather will feature a near repeat of the weather from
today into Friday morning. Look for another comfortable night
with a bit more of ridge to valley temp split expected along with
additional areas of fog - possibly dense in the river valleys -
but not quite as extensive as it was this morning. Another
pleasant day unfolds on Thursday with highs a notch higher. Look
for just the small chance for some late day showers and storms
- again mainly in our southeast counties where higher terrain and
differential heating should yield better boundaries for
initialization. Do expect the coverage to be a tad more expansive
than this afternoon/early evening owing to improving upper level
support by 00z Friday. Most of the activity will fade out with
dark allowing another quiet and comfortable night along with more
mainly valley fog into Friday morning.
Only made some minor point based adjustments to temperatures on
Thursday, though did put in some larger adjustments each night per
the ridge to valley differences anticipated. As for PoPs,
generally toned them down and smoothed them early this evening and
on Thursday pm in conjunction with the consensus CAMs guidance.
.LONG TERM...(Friday through Wednesday)
Issued at 332 PM EDT WED AUG 5 2020
The period will begin with a upper level trough starting to pull
east and northeast. At the surface an area of high pressure will
be working across the Great Lakes and northern Ohio Valley. Even
with the nearby trough expect only some higher terrain convection
on Friday afternoon. Then Saturday dry weather is expected as
high progresses further south into the Ohio Valley and heights rise
from expansion of the southern ridge eastward. Then by Sunday the
high pushes east and return flow sets in. This will bring ample
moisture back into the region and at times in combination with
ridge riding disturbances will lead to daily chances of mainly
afternoon and evening showers and thunderstorms for the new work
week. After having temperatures near normal for Friday, the
expansion of the southern ridge and return flow will combine to
warm temperatures back into the upper 80s to lower 90s for
afternoon highs going into the weekend and early next week.
There is fairly good agreement in the upper level pattern for the
long term period. Therefore stuck close to the NBM, with minor
adjustments to valleys for overnight lows and some adjustments to
the afternoon highs when compared to ridges and valleys. Also
adjusted PoPs down in some periods, where more uncertainty exists
for when these disturbances within the periphery of the ridge
arrive.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 822 PM EDT WED AUG 5 2020
VFR conditions prevailed at the start of the period, and will
generally last well into the night. Very isolated light showers
over the Cumberland drainage basin will die out this evening.
Valley fog is expected to develop overnight and grow in breadth
and depth. It is forecast to bring sub-VFR conditions to many TAF
sites toward dawn, but it will dissipate quickly after sunrise. A
few showers or thunderstorms may develop on Thursday afternoon,
especially in southeast KY. However, the prospect is too slim to
warrant inclusion in TAFs.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...HAL
SHORT TERM...GREIF
LONG TERM...DJ
AVIATION...HAL
Area Forecast Discussion
National Weather Service Pittsburgh PA
928 PM EDT Wed Aug 5 2020
.SYNOPSIS...
Building high pressure will maintain quiet and mainly dry conditions
through Thursday afternoon. Shower thunderstorm chances increase
across the ridges through the week`s end, with temperature increasing
through the weekend.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Made a few edits to sky cover and temperatures based on satellite and
observations. Previous...Dry weather and mainly clear skies are
expected tonight under building sfc high pressure. Low dew points and
radiational cooling should result in low temperatures around 5
degrees below average.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/...
Sfc high pressure should generally maintain dry conditions through
the period for the majority of the forecast area. The exception
would be across the eastern ridges, where daily shower and storm
chances exist. Guidance indicates a quasi-stationary boundary draped
across the Mid-Atlantic region (as noted in recent RAP 850mb
temperature analysis), progged to have little movement through late
Friday. Shortwave disturbances trekking through troughing aloft may
serve as sufficient forcing for ascent to initiate convection near
the aforementioned boundary given adequate llvl moisture. However,
poor mid-level lapse rates and unfavorable effective shear should
impede updraft velocity and longevity. Thus, organized, severe tstms
are not anticipated.
Upper troughing is progged to maintain near average temperature
values through Friday; though, a pattern change should be underway.
Persistent upper troughing should begin to fill in response to the
amplification of broad southern CONUS high pressure, with height
rises supporting a warm up and the return of above average
temperature Saturday. Dry conditions will accompany warming trends
under dominant high pressure.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Dry conditions and continued warmth are expected again on Sunday with
little pattern change anticipated. Long range solutions suggest high
pressure should begin to breakdown in response to an encroaching
Midwest trough, with precipitation chances generally increasing early
next week. As the trough digs across the Midwest, amplification of
overhead ridging should maintain above average temperature trends
into Tuesday.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
VFR and light winds expected through the TAF period other than a
slight chance of of MVFR vis restrictions in the morning at
FKL/DUJ/BVI/HLG.
.Outlook...
VFR conditions are expected for much of the week under the influence
of sfc high pressure, though diurnally-driven convection may be
possible each day mainly along the eastern ridges.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.
&&
$$
Area Forecast Discussion
National Weather Service Phoenix AZ
514 PM MST Wed Aug 5 2020
.UPDATE...Updated Aviation Discussion...
&&
.SYNOPSIS...
High pressure will shift east of the area through early next week
pushing thunderstorm chances into southeast Arizona and New Mexico.
This small pattern realignment will also allow temperatures to cool
a few degrees, albeit still remaining slightly above normal. This
unusually dry pattern during the middle of the monsoon may even
persist into the end of next week.
&&
.DISCUSSION...
Current WV Satellite imagery is now showing drier air advecting into
the region behind a shortwave trof that is now moving northward into
extreme southern Utah, ahead of an upper trof that will be impacting
our weather for at least the next few days. The drying is already
being felt at the sfc this hour, with the dewpoint at Phx Sky Harbor
Airport now down to 35 degrees...which helps to take a bit of an
edge off the the 110+ temps that are currently being reported.
latest HRRR forecast soundings are showing PWAT`s falling below 0.75
inch by early evening across South-Central AZ, with any TS activity
being confined to extreme SE AZ (well south and east of Tucson).
The resulting flow pattern has created a deep west to southwest flow
through the bulk of the boundary layer, and 00Z regional sounding
data sampled meager 6-7 g/kg mixing ratios largely unsupportive for
lower elevation convection. As has been the case much of the
monsoon, better quality 10-12 g/kg mixing ratios and deeper PWATs
are hovering not far away in northern Mexico though the overall
pattern through at least early next week will not promote effective
northward transport into the forecast area.
Through the remainder of this week, the aforementioned trough will
edge eastward with shortwave energy mostly deflecting north into the
Great Basin. H5 heights will relax into a 588-591dm range though
thermal ridging ahead of the trough axis will maintain a warm
midtropospheric layer. This evolution will be partially offset by a
bit of cooling in the lower boundary layer; and multi-model and
ensemble output reflects a very narrow range of forecast high
temperatures 1F-5F above normal through the weekend. Current
forecasts for the warmer Phoenix metro area suggests readings
flirting with excessive heat criteria Sat-Mon. Deeper convection
will be relegated almost exclusively to the SE corner of Arizona,
though outflows could periodically allow some moisture to advect
north and it wouldn`t be out of the question for a storm to clip
southern Gila County on any given day (though chances and coverage
don`t seem to warrant POPs anywhere even near 10%).
NAEFS membership strongly supports weak troughing persisting along
the west coast into the middle of next week, possibly being reloaded
by shortwave energy diving southeast from the Gulf of Alaska. The
most notable feature appears to be anomalous subtropical jet energy
and a positive u-wind component punching into the SW Conus. This
scenario does not bode well for any quality moisture return; and
other than the potential for a brief shallow surge of moisture,
forecast soundings depict little more than 5-7 g/kg mixing ratios
throughout the forecast area. Similar to the short term where a
stray shower/storm is possible over higher terrain locations, there
is little justification for any higher POPs or expectation of
rainfall in this type of pattern.
&&
.AVIATION...Updated at 0010Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Expect southwest to west winds with gusts to around 20 kts through
early evening with speeds diminishing later in the evening. An
easterly wind switch is expected late tonight, but will only last
through mid to late morning before again turning back to the west
Thursday afternoon. Skies will remain clear through the period
with only a few high based afternoon CU over the eastern Arizona
high terrain.
Southeast California/Southwest Arizona including KIPL and KBLH:
Breezy conditions will continue through early evening with gusts
up to around 25 kts. Winds will eventually diminish late tonight,
but gustiness is again expected for Thursday afternoon. Skies
will remain clear through the TAF period.
&&
.FIRE WEATHER...
Saturday through Wednesday: Dry conditions with above normal
temperatures will prevail through the middle part of next week in a
weather pattern more similar to June than August. Wetting rains
should not be anticipated as thunderstorm activity shifts southeast
of the districts, and only an outside chance of a shower drifting
into Gila County exists. Afternoon minimum humidity values will
generally fall into the teens across the eastern districts and
single digits over the western deserts. Overnight recovery should
range from only around 20-30 percent with locally higher values at
both higher elevations and lower Colorado River valley. Some
localized afternoon gusts 20-30 mph will be possible, but otherwise
winds will be fairly light through the period.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Percha/MO
AVIATION...Kuhlman
FIRE WEATHER...MO