Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/18/23
Area Forecast Discussion
National Weather Service La Crosse WI
1000 PM CDT Sat Jun 17 2023
.DISCUSSION...(This evening through Saturday)
Issued at 231 PM CDT Sat Jun 17 2023
Key Messages:
- Rain chances spread in overnight with the higher chances over
MN/IA. Some storms are also possible to enhance rainfall rates.
No severe storms are expected.
- Warm and dry conditions rapidly build back into the area for
next week temperatures ramping up to around 90F.
Shower and Storm Chances This Weekend
Water vapor satellite this afternoon shows a shortwave trough
slowly advancing northeast out of Nebraska. This wave is expected
to track across Iowa overnight and then into western Wisconsin
during the day Sunday. This will create an uptick in the forcing
over the area, especially late tonight into Sunday morning as the
low level moisture transport increases ahead of the trough. This
increase looks to be focused into areas mainly west of the
Mississippi River and will bring the highest rain chances across
these locations.
By late morning and into Sunday afternoon, this moisture
transport starts to get pinched off as another short wave trough
currently coming out of Colorado advances across northern
Missouri. As this occurs, the coverage of the showers will start
to diminish with only some scattered activity expected across
western Wisconsin. The latest RAP guidance suggests enough MUCAPE
will be in place overnight (250-500 J/kg) to support some thunder
across the west but with deep layer shear lacking, only expect
general thunderstorm to occur. With the heating of the day, a bit
more instability builds Sunday (500-1000 J/kg ML CAPE) but deep
shear is still lacking so again, should not be anything more than
some general thunder. The showers and storms are not expected to
be fast movers, so some potential for isolated spots of higher
rainfall totals as precipitable water amounts up to 1.5 inches
should be in place. Otherwise, rainfall amounts should generally
be a quarter of an inch or less which will not put much of a dent
(if any) into the ongoing dry conditions.
Very Warm and Dry Next Week
Major amplification of the North American flow pattern is expected
next week with deep anomalous troughing over the west with ridge
building from the southern Plains into the Great Lakes. Extreme
heat probabilities in the 17.00Z ECMWF ensemble extreme forecast
index are suggestive of above average heat, but not extreme or
record breaking. So, temperatures will ramp up Monday->Tuesday
into the upper 80s to lower 90s through Saturday. However, flow
trajectories from the east will allow dewpoints and humidities to
remain lower. With dewpoint probabilities weighted toward 60F for
the week, heat index values will remain at or below the air
temperature. Dry soils will certainly reduce any
evapotranspiration component. Thus, while the week will be warm
and dry under ridging, human heat impacts look to be minimal.
While the drought conditions over the area are expected to worsen
next week with afternoon relative humidities in the 30-40% range,
indications are that small rain chances start to enter into the
forecast again late week (Thursday) north and west of La Crosse.
But even into next weekend, questions remain and only low rain
chances look appropriate as this pattern evolves.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1000 PM CDT Sat Jun 17 2023
Slow moving upper level shortwave/sfc trough combo continue to fire
shra/ts across central IA into southwest MN at late evening. The
convection has met some resistance on its eastern flanks as it moves
out of the favorable forcing and ribbon of instability/moisture
transport and into drier air. CAMs models put the breaks on the
shra/ts...diminishing in areal coverage and (relative) intensity
through the overnight.
The shortwave, which likely experiences some enhancement from the
convection tonight, meanders over the local forecast area on Sunday
(not much for steering winds) as does the ribbon of higher
moisture/instability. Daytime destabilization will help the lift
spark scattered shra/ts, which most CAMs are in favor of. Most of
this activity should wane with the loss of daytime heating.
CIGS: NAM12/RAP suggest IFR/MVFR would be likely for at least a few
hours in the 12-18z times frame, mostly associated with rain. Not
seeing that with current convection, and would likely need more
widespread-several hours of rain to counter the current drier
airmass (to saturate that low). Some additional support from latest
numerical guidance at KRST and NBM output. Will add a few hour tempo
at KRST to address this potential, although confidence still shaky.
If it`s going to occur, low cigs should start to manifest across
northwest IA by 06z.
WX/vsby: convection should be decreasing in areal coverage as it
nears the TAF sites later tonight, sparking again during the
afternoon Sunday. Will use a mix of VCSH/TSRA to cover chances for
now. Threat for thunder (30-50%) looks higher tomorrow, currently
favored between 22-02z. Expect some vsby restrictions with any storm.
WINDS: south/southeast through Sunday night. Some higher gusts into
the mid 20 kts possible with any storm.
&&
.FIRE WEATHER...
Issued at 231 PM CDT Sat Jun 17 2023
Anomalously low dewpoints for June, and above normal temperatures,
will bring afternoon minimum relative humidity values into the
30-40% range which will help further dry fuels. Winds appear to
remain below 15 mph for the week. Rain chances, albeit low at this
time, increase for late in the week as the ridge pattern breaks
down somewhat.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...04/Baumgardt
AVIATION.....Rieck
FIRE WEATHER...Baumgardt
Area Forecast Discussion
National Weather Service Binghamton NY
933 PM EDT Sat Jun 17 2023
.SYNOPSIS...
Scattered showers and a few thunderstorms will continue this
evening, mainly east of the I-81 corridor. Additional unsettled
weather is possible early next week, although no particular day
looks to be a washout.
&&
.NEAR TERM /THROUGH SUNDAY NIGHT/...
915 PM Update...
Some isolated showers and a few areas of drizzle remain. Hi-res
guidance is suggesting another couple hours of spotty showers
before they dissipate. Then the overnight will be dry. While
coverage will be quite limited, areas that had rain today could
see some patchy fog. The afternoon update added fog in the
Chemung River valleys. Given how dry it got today, confidence is
quite low that that will occur, even with the light winds and
clear skies. For now, it remains in the forecast, mainly to
match our neighbors to the west.
Sky cover was updated as clouds slowly drift west. This will
continue overnight and could also be another factor as to why
fog does not develop tonight. Temps and dewpts were updated
again to better match obs. Areas with little cloud cover have
begun to cool now that the sun has set while areas under the
clouds and rain have been more steady.
600 PM Update...
SPC Mesoanalysis shows that most of the instability is now east
of the region, though enough remains to keep a slight chance
for thunderstorms through the evening. As expected, the drier
air is keeping the shower activity east of I-81. Showers will
continue for at least the next couple of hours before tapering
off late this evening. Only minor changes were needed to PoPs
over the next couple of hours. Elsewhere, with the dry air that
moved in, dewpoints have fallen into the 40s, resulting in 20 to
30 degree dewpt depressions. Temperatures remain in the 70s
across the dry areas. Both temps and dewpts were touched up to
better match the latest obs. Otherwise, the rest of the forecast
was doing fairly well and needed little change.
247 PM update...
Scattered showers and thunderstorms this afternoon and again
Sunday afternoon are the main concern in the near term. Severe
weather is not expected, but a few of the storms could produce
small hail, gusty winds and cloud-to-ground lightning.
Upper level low currently centered over eastern NY has a
trailing vort max that is sweeping south/sewd over central NY
and northeast PA this afternoon. The forcing from this feature,
combined with sufficient deep moisture wrapping into the system
and modest instability is helping to trigger a fairly broad area
of convection over the region. The extent of the showers and
storms is a bit more widespread and farther to the west than
previously anticipated. ML CAPE indicated on the latest SPC
mesoanalysis is roughly 300-500 J/kg with steep mid and and low
level lapse rates across the region. There is a pretty notable
cut-off between the convection to the east and nothing to the
west. This is due to a markedly drier air mass trying to move in
from the west.
The scattered showers and storms should remain confined to
mainly areas east of I-81 through the rest of the day as the
broad upper level vort max moves east and drier air starts to
nudge slowly to the east. Most of the convection should be
pulse-type and not last long in any one area. The exception to
this may be areas of the western Catskills that may get caught
in a quasi-stationary line of showers and storms between roughly
3-7 PM.
After 8 PM, due to the loss of daytime heating and the forcing
moving to the east, the convection should subside and eventually
taper off. Cloud cover should persist through the night as
moisture continues to wrap around the system to the east.
However, there could be an area over the central/western Finger
Lakes that sees a decent amount of clearing...enough to lead to
more cooling than other areas and some patchy fog late tonight
into Sun morning. There is still quite a bit of uncertainty with
this cooling/fog potential due to the drier air moving in but
the best chance is in and around the Chemung Valley,
Temperatures on Sunday will be several degrees warmer than the upper
60s and 70s seen today. Afternoon highs on Sunday will warm
well into the 70s for much of the forecast area.
The potential for showers and storms on Sunday should be quite
lower than today given the lack of a real mechanism for forcing.
There is some indication of a weak short wave dropping south
across the region...which will combine with afternoon
instability, so convection may be more sparse than today. Low
level moisture Sunday night may be higher than tonight, which
may lead to more fog in Monday morning.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
305 PM Update...
A shortwave drops into New England on Monday likely keeping the
chance for any showers and thunderstorms to the east. Slight
chance to chance PoPs were kept for along and east of I-81
though trends in the models have been towards a weaker shortwave
so if this trend continues, than afternoon rain showers and
thunderstorms may have to be lessened farther.
Monday night into Tuesday, a rex block sets up with a strong
area of high pressure over the Great Lakes region and a cut off
low over the SE US. Initially as the rex block is getting set
up, good low level convergence in addition to some moisture in
place, isolated to scattered showers and thunderstorms develop
on Tuesday. Chances of precipitation were limited as of now due
to a subsidence inversion developing through the day and if the
high pressure builds in faster, it will limit the coverage of
storms on Tuesday.
Tuesday night into Wednesday, the upper level ridge builds in
with temperatures warming to near to above average. Chances of
precipitation were kept Wednesday afternoon but mostly limited
to where there is more terrain. Forecast soundings show some
instability though with the capping it will be tough to get
anything going away from the taller hills and mountains like the
Catskills, Poconos, and areas of Steuben county. Smokey skies
will be possible to likely given the flow almost due northerly
with the trough over New England through the short term. How
thick the smoke could be will be determined by how active the
fires get. Given that 500 mb heights will be well above
climatological means where the fires are, odds are temperatures
will also be well above average so right now it looks like there
will be favorable conditions for active fires.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
305 PM Update..
The rex block will persist through much of the long term.
Afternoon precipitation chances were lowered as it looks like
the center of the upper level ridge will be over us mid week
with strong capping. With the addition of smoke as well surface
heating may be lowered slightly as well as mid level warming so
that is working against any pop up afternoon showers and
thunderstorms. Temperatures were kept with the NBM with
widespread low to mid 80s each afternoon. If there is thicker
smoke, then temperature will need to be lowered but if the smoke
plumes dont materialize, then the forecast highs are too low.
Towards the end of the week, the upper level ridge associated
with the rex block moves east with the flow becoming southerly.
This should help with the smoke as well as bring in better low
and mid level moisture. Precipitation chances begin to return at
the end of the week into early next weekend with the return of
low level moisture and weaker capping in place.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
A few VFR showers will affect KRME and KSYR until around 05z.
Rest of our terminals in central NY and northeast PA will be VFR
this evening. We expect MVFR ceilings at a few of our terminals
which will work down from the northeast around the large upper
level low that has passed to our east. MVFR ceilings will reach
KRME first around 05z, then between 09z and 11z at KSYR, KITH
and KBGM. KBGM will likely see fuel alternates for a time around
12z. KELM could see some IFR fog which is KELM`s fuel alternate
between 08z and 12z. There is considerable uncertainty as to
how much fog and visibility restriction occurs at KELM. Very dry
air has blased southeast with dewpoints plummeting to around
40F in KELM. But HRRR and other models raise dewpoints tonight.
So for now have a tempo group in for IFR fog for KELM 08z to
12z. For KAVP, it looks like VFR conditions.
Northwest winds will be around 5-10 knots overnight. Winds are
expected to pick back up from the north Sunday morning after
15Z closer to 10 knots with a few gusts in the afternoon under
20 knots.
Outlook...
Sunday night through Tuesday...Mainly VFR; scattered
afternoon/evening shower becoming gusty around 20 kt and should
remain breezy through the afternoon before subsiding back to
below 10kts after sunset this evening.rs & thunderstorms
possible with occasional restrictions possible.
Wednesday and Thursday...Mainly VFR
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...BJT
NEAR TERM...BTL/BJT
SHORT TERM...AJG
LONG TERM...AJG/MJM
AVIATION...DJN
Area Forecast Discussion
National Weather Service State College PA
1115 PM EDT Sat Jun 17 2023
.SYNOPSIS...
Upper level troughing over the northeast CONUS will slowly give
way to an upper ridge building in from the Great Lakes the
second half of next week. The remnants of a cut off low over the
southeast states is likely to lift through the region late next
week, as the upper ridge shifts off the east coast.
&&
.NEAR TERM /THROUGH SUNDAY/...
Late evening satellite loop shows mainly clear skies across
central PA through a veil high level smoke from Canadian
wildfires. Dry air and a diminishing breeze associated with high
pressure building into western PA should result in efficient
radiational cooling, especially over the western counties. Readings
are likely to dip into the 40s over the Alleghenies and the 50s
in the Susq Valley. The chilly air, combined with water temps
near 70F, should result in patchy late night fog in the deep
river/stream valleys of the NW Mtns and Laurel Highlands.
Rising heights resulting in fair and warmer weather is expected
Sunday, as the upper low over New England lifts into the
Canadian Maritimes. Model RH fields and the latest HRRR Smoke
Model support a mix of cumulus and high level smoke over the
northeast part of the forecast area Sunday, with mainly sunny
skies over the southwest counties. Mixing down model temps at
800mb yields expected high temps ranging from the mid 70s over
the N Mtns/Laurel Highlands, to the mid 80s across the Lower
Susq Valley.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
Rising heights in between the exiting low over the Canadian
Maritimes and a cut off upper low meandering over the western
Ohio and Tennessee Valleys signals mainly rain-free weather and
warming temperatures for central PA into early next week.
However, a southeast flow off of the Atlantic is likely to
temper the warmup a bit.
Increasing low level moisture and lingering troughing aloft
could yield isolated-widely scattered diurnal convection Monday
and Tuesday, but ensemble plumes indicate most locations remain
dry.
After a string of cool nights, expect a return to summerlike
lows in the upper 50s to mid 60s Monday night, as low level
moisture returns. Highs early next week should range from the
upper 70s to mid 80s over most of the area.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
On the large-scale pattern, ensemble prediction system
agreement has become pretty good for later next week. This
pattern should consist of continued upper-level blockiness, with
a northwestern Atlantic closed low, an expansive ridge axis
slowly building from the middle of the country into the Great
Lakes and Northeast, and a piece of weakening upper-level energy
getting cut off from the westerlies and dropping into the TN
Valley/Southeastern states.
The above noted pattern should result in warmer, more typical
summer-time conditions than we`ve seen anytime in the last 6-8
weeks. Mostly rain-free weather should prevail, with convection
isolated-widely scattered in nature, and relegated mostly to the
afternoon and evening hours. A chance of more widespread showers
and meaningful rainfall could come Friday or Saturday, as the
remnants of the cut- off low over the southeast states lifts
north toward the area.
A southeast flow off of the Atlantic will likely temper daytime
highs across much of central PA the second half of next week,
despite rising heights aloft. Daily highs should be close to
seasonal in the upper 70s and low 80s most spots. Warmer
conditions, especially at night, are possible by Friday/Saturday
as low level flow veers from southeast to south ahead of the
remnant upper low.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
A few wind gusts to around 20 knots will remain possible for
the next hour or two before decreasing after sunset as weak high
pressure builds in from the west. VFR conditions are expected
across almost all of the area although some patchy valley fog is
possible across the western mountains overnight into the early
morning hours. It appears that BFD would be the site that is
most likely to see any visibility restrictions tonight, so the
potential for MVFR visibilities has been included in the TAF.
Any fog that develops overnight will dissipate quickly after
sunrise and VFR conditions will prevail through the day
tomorrow.
Outlook...
Sun Night-Mon...Predominantly VFR.
Tue-Thurs...Brief restrictions possible in scattered SHRA/TSRA.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Fitzgerald
NEAR TERM...Fitzgerald
SHORT TERM...Lambert/Fitzgerald
LONG TERM...Jurewicz/Fitzgerald
AVIATION...Bauco/NPB
Area Forecast Discussion
National Weather Service Cheyenne WY
525 PM MDT Sat Jun 17 2023
.SHORT TERM...(This evening through Monday night)
Issued at 330 PM MDT Sat Jun 17 2023
Isolated thunderstorms are currently ongoing across the CWA this
afternoon, with a stronger line just south of the border in northern
Colorado. Latest GOES WV Imagery shows an upper-level low spinning
over northern North Dakota with drier air south of the low and
across most of the western CONUS. Current temperatures range from
the mid-50s to mid-60s west of I-25 and low- to mid-70s east of I-
25. Convection moved over CYS earlier, keeping temperatures lower
than originally forecast for the day, and the cloudy skies will
likely inhibit any temperature recovery this afternoon. The HRRR and
NAM Nest move all precipitation out by 00Z this evening before a
drier pattern takes hold.
A warm and dry pattern begins Sunday and continues through Tuesday
as an upper-level ridge builds over the central CONUS. Westerly to
southwesterly flow aloft takes over to start the week as the upper-
level ridge builds and an upper-level trough pushes over the Pacific
Northwest and slowly moves easterly. Warm temperatures aloft coupled
with subsidence from the upper-level ridge inhibits precipitation
chances through the beginning of the week. Monday looks to be the
warmest day with several locations in western Nebraska reaching the
low- to mid-90s during the day, with locations in southeast Wyoming
approaching the low-80s. As upper-level height gradients tighten
Sunday as the low moves towards the Pacific Northwest, winds will
pick up significantly, especially over south-central Wyoming. Winds
will be close to 30 kts across Carbon County on Sunday, Monday, and
Tuesday, with gusts approaching 40 kts each day. Tuesday looks to be
the windiest day, with gusts approaching 45 kts in portions of
Carbon County.
.LONG TERM...(Tuesday through Saturday)
Issued at 330 PM MDT Sat Jun 17 2023
Windy conditions Tuesday as CWA in southwest flow ahead of a
slowly approaching low pressure system moving into Idaho. Surface
front looks to be located near the Wyoming/Idaho state line at
12Z Tuesday. 700mb winds across Carbon and Albany Counties
40-45kts. Did increase winds across Carbon County about 4-8kts
from guidance. May need to increase further as we get closer to
the event. Tuesday will be warm...but with increasing clouds and
cold air advection from the west...temperatures could be dampened
some. Did lower afternoon highs over Monday by 3-4 degrees.
Cold front moves into the CWA Tuesday night into Wednesday
morning. GFS and ECMWF does show convection beginning to break
out Wednesday afternoon...so did add some chance PoPs into the
forecast.
GFS does go a little bonkers on QPF over the Panhandle Wednesday
night into Thursday with over an inch of 6 hour QPF. Could be
convective contamination that frequently affects the GFS because
the ECMWF much shows less. Will see how this solutions pans out as
we get closer to the event.
Unsettled weather Thursday and Friday as we continue to get pieces
of shortwave energy move through the southwest flow both days. Have
pretty high PoPs in the forecast each afternoon and early evening
before convection decreases overnight.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 523 PM MDT Sat Jun 17 2023
VFR conditions expected through the 00Z TAF period. Generally
light winds with clearing skies overnight. Winds begin to increase
after 16Z with wind gusts 30 to 40 knots across SE WY and 20 to 30
knots in the NE Panhandle.
&&
.FIRE WEATHER...
Issued at 330 PM MDT Sat Jun 17 2023
Limited fire weather concerns due to ample moisture across the
region. Warmer temperatures are expected with several locations in
western Nebraska reaching the low 90s. Afternoon RHs drop into the
low-20s as the temperatures increase. The biggest concern will be
the strong winds expected Sunday through Tuesday. Sustained winds
near 30 kts with gusts as high as 40 kts are possible across south
central Wyoming.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...AM
LONG TERM...GCC
AVIATION...LK
FIRE WEATHER...AM
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1157 PM EDT Sat Jun 17 2023
.AVIATION...
Clear sky and calm wind is maintained by high pressure drifting
across SE Mi late tonight and early in the morning. Fog is less of a
concern tonight due to the dryness of the resident air mass and with
near surface smoke dissipated considerably compared to last night.
High pressure then drifts into the eastern Great Lakes by afternoon
while still holding control of conditions in SE Mi. Clear sky
continues with light SE wind augmented by lake breeze once again
into Sunday evening.
DTW THRESHOLD PROBABILITIES...
* None.
&&
.PREV DISCUSSION...
Issued at 336 PM EDT Sat Jun 17 2023
DISCUSSION...
Mid/upper level ridge axis continues to track across the Upper
Midwest and into the Great Lakes this afternoon providing dry and
stable conditions while reinforcing moderating thermodynamic
profiles into next week. Very dry boundary layer precludes any
additional diurnal cumulus development as GOES imagery shows the
erosion of what little arose over Metro Detroit midday. Slight
obscuration in visibilities persists as both HRRR and RAP Smoke
models affirm the ducting of Canadian wildfire smoke into the near-
surface layer which should maintain a thin haze. Favorable nocturnal
cooling setup ensures a comfortable evening with overnight lows
generally near 50F throughout the outlying areas.
Associated surface high pressure emerges over the Ohio Valley Sunday
morning resulting in a southerly wind shift and weak warm advection.
The surface high then takes on a more easterly trajectory Monday as
it settles into the Alleghenies with local winds backing toward the
east, although pressure gradient forces still appear rather benign.
Aloft, a weak cutoff low looks to ride a secondary/reinforcing ridge
near the western Great Lakes Sunday as it gets pinched south of the
state. This keeps conditions dry across Lower Michigan. Meanwhile
three of PV anomalies will consolidate over the Northeast,
effectively trapping/blocking the composite ridge (and associated
anemic flow aloft) over Michigan while thicknesses build through the
midweek timeframe.
Extended range MOS data is currently more bullish than the latest
ensembles regarding temperatures Tuesday through Friday, exhibiting
higher confidence in 90F readings for one or more days. Given the
persistent easterly flow, nearshore communities and those downwind
of the lakeshores should be much cooler then interior locations.
First real opportunity for precipitation arrives Friday or Saturday
with the development of a Gulf moisture feed that helps elevate
dewpoints into the mid-upper 60s. Combined with the aforementioned
orphaned low to the south opening/releasing northward, greater
potential exists for convection next weekend.
MARINE...
High pressure now situated across the Great Lakes will bring an
extended period of lighter winds this weekend and into early next
week. Wind direction from the north-northwest will turn more
variable late tonight as the high pressure takes hold. Influence of
this system will also bring dry weather through at least early next
week.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&
$$
AVIATION.....BT
DISCUSSION...KGK
MARINE.......AM
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Peachtree City GA
938 PM EDT Sat Jun 17 2023
.UPDATE...
Issued at 937 PM EDT Sat Jun 17 2023
Evening convection has diminished across the CWA. Have made only
some minor tweaks to the hourly T and Td grids.
&&
.SHORT TERM...
(This afternoon through Sunday)
Issued at 300 PM EDT Sat Jun 17 2023
At 3 PM, the diurnally driven cumulus field was becoming
increasingly agitated along a frontal boundary over central
Georgia. Radar was picking up isolated echos, with the majority
of the activity near the Georgia/Alabama border. North of the
boundary conditions were quieter in the mountain of northern
Georgia. Temperatures were in the upper 80s over most of the
region, at or just shy of convective temperatures.
Through Tonight:
Isolated showers and thunderstorms will continue along an south of
Interstate 20 through around 9 PM this evening. The majority of
these storms will be non severe, but they could produce lighting
and interrupt evening activities. If any of the storms do trend
towards the stronger side, there could be an isolated risk for
downdraft activity in central or east central Georgia (where SPC
Mesoanalysis suggests DCAPEs near 1200 j/kg and the CAMs show
inverted V soundings below 850 mb).
Surface winds should become light and variable tonight. This could
open the door for some patchy fog formation across portions of
central Georgia. As a whole the CAM guidance has been trending
away from this potential and forecaster confidence in fog
formation is low (< 20%). Thus for now we left fog out of the
official forecast.
Considerations for Sunday:
A weak shortwave trough should slide from the Tennessee Vally into
Georgia on Sunday. This wave should promote thunderstorm activity
over portions of Alabama and southern Georgia where the best
instability will be present. The various CAMs are offering up a
wide range of potential outcomes regarding thunderstorm coverage
in north and central Georgia Sunday afternoon and evening. These
outcomes appear dependent on the degree of available instability.
The majority of the members suggest limited instability, with the
HREF mean being at or below 1000 j/kg. The HRRR is the most
bullish of the CAMs in allowing SBCAPEs to climb to around 1500
j/kg Sunday afternoon in central Georgia. For now or forecast
keeps rain chances in the 20 to 40 percent range Sunday
afternoon. Any rainfall that does occur should be brief.
Sunday should be the last day with high temperatures near
seasonal averages before a mild weather pattern kicks in for the
workweek. Expect afternoon highs in the upper 80s and lower 90s.
Albright
&&
.LONG TERM...
(Monday morning through next Friday)
Issued at 300 PM EDT Sat Jun 17 2023
The story of this AFD long term can be summarized in one word: wet.
Aloft, a strong low moving into the Pacific NW will lead to pumping
of the ridge in place over the central CONUS. A rossby wave break
eventually occurs, allowing for what at first appears to be some
movement in what has otherwise been a rather stagnant pattern, but
the hope is short lived. All guidance is in alignment in showing a
PV anomaly getting trapped underneath the high that breaks and
becomes closed, and we quickly find ourselves in a rex blocking
situation with a cut off low sitting right on top of the southeast.
This pattern pretty much remains through most of the long term, with
surprisingly little deviation among most of the long term models and
ensembles.
For us, that means moisture will be streaming into the area up and
around the low pressure center. And it will be doing it pretty much
through the entirety of the long term. This means there will chances
for repeated rounds of heavy precip through the week. The first
round will likely be on Monday as the system moves into the area,
and then each day will have chances of rain aided in part by day
time heating. Where the heaviest rain falls will likely be dependent
on where the low ends up moving. Best chances will generally be on
the eastern side, so any small shifts east or west could have big
implications on total rainfall, and models tend to struggle with
direct placement of any kind of cutoff low.
Overall, rainfall across the long term forecast has 2-5" of QPF from
Monday-Friday. Ensembles give a little better view of the potential
if an area were to see repeated rounds of heavy rainfall from the
system, with some members showing as much as 6-7" possible. This
likely wouldn`t be widespread, but certainly wouldn`t want to
rule out the possibility - especially since this amount of
rainfall, even over a longer period such as 5 days, could
certainly cause some flooding or flash flooding issues.
Lusk
&&
.AVIATION...
(00Z TAFS)
Issued at 723 PM EDT Sat Jun 17 2023
SHRA/TSRA continue to push well south of ATL. Convective activity
should diminish with sunset. Hi-res models progging only isold
activity tomorrow with more widespread rain overnight. Winds will
go light and vrb overnight and could go east for a few hours
before mixing kicks in Sunday morning.
//ATL Confidence...00Z Update...
Med confidence winds. High confidence remaining elements.
NListemaa
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 64 90 67 82 / 10 20 50 80
Atlanta 67 90 69 82 / 20 40 60 80
Blairsville 57 84 62 76 / 0 30 60 80
Cartersville 63 91 67 82 / 10 30 70 90
Columbus 67 90 69 82 / 30 30 60 80
Gainesville 64 89 67 80 / 10 30 50 80
Macon 67 92 68 82 / 30 40 50 80
Rome 63 92 68 84 / 0 30 70 80
Peachtree City 64 92 67 83 / 20 30 60 90
Vidalia 69 91 71 87 / 40 20 20 80
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...NListemaa
LONG TERM....Lusk
AVIATION...NListemaa
Area Forecast Discussion
National Weather Service Gray ME
1047 PM EDT Sat Jun 17 2023
.SYNOPSIS...
Upper level low pressure continues to bring rain and a few
thunderstorms to the region, which has resulted in some flooding
today and will last through the evening. Low pressure moves
away on Sunday with improving conditions in our neck of the
woods. A few weak disturbances may be the cause for a few
showers and thunderstorms Monday through early Wednesday, but
the predominant weather should be dry. A return to summertime
warmth conditions is likely mid and late next week as ridging
builds across the Northeast.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
0245Z Update...
Minor update late this evening with data appearing to be flowing
to AWIPS and the web this hour. Will continue with a slight
chance of a thunderstorm tonight, but mainly over eastern and
northern areas. Patchy fog with shower activity continuing
before diminishing from west to east overnight.
0100Z Update...
Have decided to end the flash flood watch as precipitation rates
remain manageable across the forecast area. Some pockets of
heavy rain will continue however, with localized flooding
possible. Latest radar imagery continues to show the strongest
echoes in northern and eastern portions of the forecast area,
however some of this is due to bright banding.
The latest HRRR indicates the precipitation weakening as they
retrograde towards New Hampshire and southwest Maine during the
overnight hours as drier air in the lower levels enters the
region as low level winds continue to back.
Update...
Latest radar imagery continues to show showers retrograding
westward from the Gulf of Maine early this evening and into the
region. Convection offshore has moved into the Midcoast region
where rainfall rates have increased. This precipitation
continues to be picked up well by the latest HRRR and expect an
additional inch of rain in the mountains this evening and the
Midcoast region.
Have made minor adjustments to the temperatures, dew points and
wind forecasts this evening.
Prev Disc...
Expectations for the rest of today into tonight have not
changed much with this forecast package as we continue the Flood
Watch. Highest rainfall rates and totals we have seen today
thus far have been across southwestern NH close to the center of
the upper low and surface trough axis where there is more
instability and little to no mean flow, allowing showers and
storms to persist over the same areas for longer durations.
Short-range guidance has the threat for these torrential
downpours continuing through at least into early evening across
NH before instability wanes. However, showers do remain possible
into the early overnight across NH.
Crossing over into Maine, there has been a steady light to
moderate rain for most of the day with lower rain rates thus
far. However, satellite is showing more convection blossoming
with cooler cloud tops over the Gulf of Maine so I expect to
see an uptick of embedded heavier cells and rain rates within
the steady rainfall the rest of this afternoon and evening,
especially as the low-level jet continues to ramp up in this
environment with a fairly deep warm cloud layer and PWATS over
the 75th percentile. Areas that see these repeated heavy
downpours could see flooding issues, especially if over same the
regions where heavy rain fell yesterday. While the threat for
thunder is low in Maine, have followed pretty closely to the
HRRR`s depiction and continuing a slight chance.
Shower chances well start to taper off overnight from west to
east as the better forcing also shifts east, especially across
NH. All in all, a widespread 1 to 2 inches is still expected
before all said and done, but as we have seen already today,
locally higher amounts of 3 to 4 inches will certainly remain
possible. With upslope enhancement, the highest amounts are
still expected in the mountains.
On top of the heavy rain and flooding potential, the pressure
gradient will tighten as the low-level circulation continues to
slowly lift to the north and east across the Gulf of Maine but
remaining offshore of the Midcoast, resulting in developing
breezy conditions. Winds across western ME could gust between 25
and 35 mph this evening through tonight, with up to 40 mph not
out of the question. Given the very saturated ground conditions
along with these winds, a few trees could be knocked down.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
The area of low pressure will continue its trek across the Gulf of
Maine through the day Sunday, forecast to be centered near Nova
Scotia by late afternoon or early evening. We`ll start the day
mostly cloudy, but as the low progresses farther north and east,
conditions will gradually improve from west to east through the day,
with decreasing cloud cover expected across NH and far western ME.
As far precipitation goes, any leftovers of the widespread, steadier
precip will be confined to western ME early in the day, more notaably
toward the Midcoast/August regions, but this is expected to come
to an end through the morning hours. However, isolated to scattered
showers will be possible through the day, especially where more
breaks in the clouds occur or in the upslope regions, which looks
to be mainly across NH. Max temps will be in the 60s for most,
and a bit warmer in the lower 70s across southern NH.
Any showers that manage to develop in the afternoon should dissipate
by Sunday evening once the sun goes down. Winds are expected to be
light for the overnight hours, and I think given the recent rains
and still sufficient low-level moisture, that fog could develop in
some areas. Overnight lows look slightly cooler, low-mid 50s in
southern areas and upper 40s to the north.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
A blocky hemispheric pattern persists through the long term but
this time with some hope for a break from the dreary weather
we`ve experienced in recent weeks. There is an inherent level of
uncertainty associated with any blocky pattern, as features
struggle to move (or not), so I wouldn`t rush to make dry-
weather plans just yet... however there is growing consensus in
the model suite bringing a stretch of drier and warmer weather
for the end of the coming workweek. It may be short- lived,
however... with PoPs returning for the weekend.
Starting off on Monday... an omega block will be present over
the Canadian Maritimes, with low pressure centered just south of
Nova Scotia/Newfoundland and high pressure over Labrador. In
the upper levels, a complex low pressure area with a few
impulses pivoting around it will be spinning overhead. One
impulse will be moving through on Monday, offering a quick hit
of light rain showers. Otherwise flow is expected to turn
onshore during the afternoon which combined with partly or
mostly cloudy conditions will limit temperatures to the 60s to
around 70 in the north and east, though warmer temperatures are
expected further from these influences in western zones or the
southern interior. Another one of these upper level impulses
pushes down through New England on Tuesday with another round of
light, widely scattered rain showers... with temperatures
expected to be similar, topping out around 70 degrees for much
of the area. Some weak instability may pop off a few afternoon
thunderstorms on each day, with the expectation that these would
occur over the interior, away from stable maritime air.
By mid-week, there`s good signal that the downstream block
breaks down and allows for some eastward progression of the
upper level pattern. This would allow for a building ridge over
the Plains and Great Lakes to shift east into our area, phasing
with high pressure over the Maritimes. From a pattern
perspective, this should allow us to dry out with PoPs
suppressed by the ridge itself... plus a warmer airmass will be
advecting in from the northwest with the ridge. Temperatures
thus will trend warmer through the middle and end of the week
with highs in the 70s to near 80 on Wednesday... and up likely
into the 80s to near 90 on Thursday and Friday. Weak flow will
allow for daily sea breezes which serve to limit warming along
the coast, as usual. The further out in the forecast the less
certain the upper level pattern is due to the slow, blocky
movement of major features... and the potential development of
another omega block over the eastern CONUS. In general height
and pressure falls are likely by this weekend with an eventual
return to showery weather. Have capped PoPs at a slight chance
or low- chance this weekend with the expectation that these
could be delayed further if the wave pattern stalls out again...
as the fresh 12Z ECMWF suggests.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Short Term...A few sites may be able to reach low-end MVFR
through tonight, but for the most part IFR to LIFR are expected
as widespread showers, some heavy at times, continue over the
region. Precipitation is expected to taper off from west to east
very late tonight into early Sunday morning but it will also
get breezy tonight, especially across Maine. Some sites could
return to MVFR overnight.
Long Term...Periodic restrictions due to showers, isolated
thunderstorms, and overnight fog/low CIGs are expected Monday
through Tuesday night. High pressure builds through the middle
and end of the week with prevailing VFR, although overnight
FG/BR and accompanying low CIGs are possible... especially in
interior river valleys. Winds are expected to be quite variable
in direction through the week but light overall.
&&
.MARINE...
Short Term...Slow-moving low pressure across the Gulf of Maine
will keep SCA conditions across the waters tonight through most
of Sunday. Can`t rule out a few gusts approaching Gale Force
near the Midcoast and Penobscot Bay as well this evening and
tonight. Winds and seas will start to come down Sunday afternoon
and evening as the low pressure lifts away from the area.
Conditions will then remain below SCA levels through Sunday
night.
Long Term...Winds and seas are forecast to remain below SCA
thresholds through the upcoming workweek. Showers, lowered
visibility, and perhaps a thunderstorm or two may impact the
waters Monday through Tuesday night before high pressure pushes
in a dries the region out a bit.
&&
.HYDROLOGY...
Heavy rain fell across the region today with generally one to
three inches of precipitation with locally higher amounts. Our
highest report was 5.8" observed in Newport New Hampshire.
For the rest of the night, rain showers will continue to
retrograde around the periphery of the coastal low back into
Maine and New Hampshire. Rain may continue to be heavy at times
with an isolated thunderstorm or two, however much of the
steadiest and heavist precipitation will continue to gradually
diminish overnight and into Sunday morning. Therefore the flash
flood watch has been discontinued.
Areas rivers should remain in their banks per latest trends as
of 01Z.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until noon EDT Sunday for ANZ150>154.
&&
$$
NEAR/SHORT TERM...Cannon
LONG TERM...Casey
Area Forecast Discussion
National Weather Service Wilmington NC
901 PM EDT Sat Jun 17 2023
.SYNOPSIS...
Isolated showers and storms return Sunday and Monday as moisture
returns slowly to the area. Meandering low pressure, surface
and aloft, will affect the area with unsettled weather for much
of the upcoming week with temperatures likely running below
normal.
&&
.UPDATE...
Quiet night underway, and no forecast changes necessary at this
time. Sea breeze front is apparent on radar about 50 miles
inland and still progressing. Increasing RH may lead to patchy fog
development later tonight. If it does development, it may become
particularly dense across portions of Brunswick and Columbus
counties that are impacted by smoke from the Green Swamp fire.
We`ll be closely monitoring that area for the possible issuance
of a Dense Fog Advisory.
&&
.NEAR TERM /THROUGH SUNDAY/...
Weak high pressure extending in from the north and front to the
distant south will maintain light and variable prevailing winds
which will shift to the south in sea breeze into early this
evening and then become near calm. Overall quiet weather through
Sun morning with potential for localized shwrs/tstms associated
with convergence along the sea breeze boundary. Temps will
remain slightly above normal with near 90 most places for highs
on Sunday and mid to upper 60s for lows.
Dewpoints in the mid 50s will recover into the 60s through this
evening and into tonight, but moisture is still lacking for the
most part through the column for much in the way of fog and
should remain rain-free through Sun morning for most places.
Included some patchy fog, but confidence is low as it looks to
be too dry. Hi res models showing storms to the south associated
with passing shortwave overnight and possibility of stray
shwr/tstm spreading up from south and reaching into southern
tier of forecast area, but kept out any iso pops until early morning.
As sea breeze pushes inland late this afternoon into this
evening, winds will back around to the S. This will shift the
smoke plume from Pulp Rd fire in the Green Swamp to blow toward
the north which HRRR shows affecting NW Brunswick into the
borders or portions of Columbus, Pender and Bladen counties into
this evening and calming down overnight as nocturnal inversion
sets up and winds diminish to near calm.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
This period looks to be relatively the driest as we head into next
week. Mainly diurnal convection is expected headed into Mon
afternoon as moisture advection increases from the south and a
deepening trough aloft looks to become a cut off low more towards
the evening. This low will funnel waves of shortwave energy over our
area with one arriving towards the end of the short term period.
Better moisture/forcing looks to remain in NE SC with relatively
higher POPs in that area. No severe weather is expected at this
time. Lows in the mid to upper 60s throughout the period with highs
in the upper 80s to near 90 on Mon.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
Unsettled weather looks to continue headed into the long term period
as the closed upper low continues to supply lift and moisture to the
area. Adding to this, surface low pressure could also form along the
coast headed into midweek, lingering there through the end of the
period. This could locally enhance lift in those area which, when
paired with guidance showing PWATs near 2.0" (nearing possibly 2.5"
towards the end of the work week), could result in periods of heavy
rainfall. Best chances for rain at this time look to be Tues and Wed
but would not be surprised if POPs increase into late week if
conditions do not change. Surface high pressure looks to try to
wedge down from the north midweek which could lead to slightly
cooler lows inland, but at this time lows look to remain in the 60s.
Highs roughly near 80.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
Light/variable winds will swing slowly around to W and then SW
under weak high pressure. Possible MVFR VSBY restrictions from
fog toward daybreak. With increasing low-level moisture Sunday,
isolated showers/tstms will be possible, although the marine
layer should keep them away from the coastal terminals. Coverage
is expected to be too sparse for inclusion at this time.
Extended Outlook... Mainly VFR through the weekend. Next
potential threat flight categories arrives by Monday, as more
unsettled weather arrives.
&&
.MARINE...
Through Sunday...Weak high pressure will maintain light and
variable prevailing winds but decent sea breeze development, so
winds backed towards the S through this evening with higher
gusts. Fairly weak SE flow on Sunday will become increasingly
onshore in the afternoon sea breeze which should provide some
gusty winds through early Sun evening near shore. Seas will
remain 3 ft or less with some chop in the aftn sea breeze. A 7
second longer period minimal SE swell will mix in.
Sunday Night Through Wednesday...
Sub-SCA conditions look to persist into midweek before both wind
gusts and seas begin to near thresholds. SE`ly flow briefly backs to
NE`ly Mon morning due to the influence of offshore low pressure.
Winds then become predominantly E`ly for the rest of the period.
Come late Tues into Wed, high pressure will start to ridge down from
the north while low pressure forms to the south. This will act to
tighten the pressure gradient leading to increasing wind speeds and
seas responding in turn paired with an increasing ESE`ly swell at 7-
8 seconds. Confidence on SCA is low at this time due to the
uncertainty around the forming low as well as how long the high
pressure will stay in the area, but wind speeds look to reach 10-15
kt with seas 3-5 ft come late Wed into Thurs at this time.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...Coastal Flood Advisory until 1 AM EDT Sunday for NCZ107.
MARINE...None.
&&
$$
SYNOPSIS...ILM
UPDATE...CRM
NEAR TERM...RGZ
SHORT TERM...LEW
LONG TERM...LEW
AVIATION...CRM
MARINE...RGZ/LEW
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
935 PM EDT Sat Jun 17 2023
...New UPDATE...
.UPDATE...
Issued at 928 PM EDT Sat Jun 17 2023
Upper and surface ridging across the Tennessee valley and southern
Appalachians overnight through much of Sunday. Dry airmass with
clear sky and light/calm winds will allow temperatures to fall to
5 to 10 degrees below normal. Some patchy fog near area lakes and
streams is possible.
&&
.SHORT TERM...
(This evening through Sunday)
Issued at 322 PM EDT Sat Jun 17 2023
A weak ridge and high pressure will be over the region tonight
through tomorrow morning. Tomorrow afternoon a weak trough will
creep towards the region bringing increasing rain chances mainly
after this forecast period. There will be a low chance for showers
and storms late tomorrow afternoon/evening mainly south of I-40.
Some haze may linger this evening with northerly flow sending
smoke from Canada toward the region but overall conditions should
be improving tonight according to HRRR smoke products. Vis
restrictions due to haze have been minor and few and far between
today.
A fairly dry air mass remains in place, with dew points in the 50s
and lower 60s. Lows will be seasonally cool mainly in the 50s.
Highs tomorrow will be seasonable near 90 in the TN Valley.
&&
.LONG TERM...
(Sunday night through next Saturday)
Issued at 322 PM EDT Sat Jun 17 2023
Key Messages:
1. Unsettled pattern with chances for showers and storms through the
period.
2. High temperatures will be generally be near to below normal.
Discussion:
A short wave aloft will approach Monday night, with a cutoff low
forming over the region by Tuesday night. Models generally show
this upper low drifting south then perhaps west, although the
details are still uncertain as the models are not consistent and
typically have a notoriously difficult time handling the exact
evolution of these types of systems. However, right now it does
appear that the weak will feature unsettled weather, with showers
and thunderstorms around at times through the period.
Operational model and ensemble data suggests the convective energy
may be higher early in the period, although there are large
disparities between models. For example, the NAM soundings suggest a
possible severe threat Monday given MLCAPE values near or in excess
of 2000 J/kg over much of the area and significant effective shear,
but the GFS shows MLCAPE values generally less than 250 J/kg. This
certainly warrants continued monitoring. There does still appear to
be a threat of flooding during the period given significant moisture
and repeated rounds of showers/thunderstorms, and in these types of
patterns there is also a threat of training. The flooding risk will
continue to be mentioned in the HWO. With the upper low expected to
hang around for much of the week, expect high temperatures to
generally be near to below normal.
&&
.AVIATION...
(00Z TAFS)
Issued at 654 PM EDT Sat Jun 17 2023
Upper and surface riding will keep VFR conditions throughout the
forecast period. Winds will increase out of the south to southwest
Sunday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 62 91 69 82 / 0 20 60 80
Knoxville McGhee Tyson Airport, TN 58 88 67 81 / 0 10 20 70
Oak Ridge, TN 59 90 66 81 / 0 10 30 70
Tri Cities Airport, TN 52 86 64 83 / 0 10 10 60
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...DH
AVIATION...DH
Area Forecast Discussion
National Weather Service San Francisco CA
543 PM PDT Sat Jun 17 2023
...New AVIATION, MARINE...
.SYNOPSIS...
Issued at 1130 AM PDT Sat Jun 17 2023
Onshore winds increase late tonight into Monday with another round
of marine stratus and cooler temperatures. Cool temperatures
persist into next week with troughing along the West Coast.
&&
.SHORT TERM...
(This afternoon through Sunday)
Issued at 802 AM PDT Sat Jun 17 2023
The storm track was located to our north this morning with an
expansive mid-level anticyclone centered across the eastern
subtropical Pacific. A low amplitude perturbation was noted on
moisture channel imagery approaching the Pacific Northwest with
upstream low pressure located across NW BC. Surface high pressure
encompassed much of the eastern tropical and subtropical Pacific,
with a stationary front extending from SW OR into NE WA.
By this evening look for the upstream low pressure area to drop down
the BC coastline before reaching the Pacific Northwest states on
Sunday. This will drive the aforementioned front equatorward as a
cold front, with the front dropping south through the Bay Area late
tonight and the Central Coast on Sunday. After a relatively mild day
today with inland areas climbing well into the 80s, look for a
breezy and blustery cool down by Sunday with highs mostly in the 60s
and 70s. W-NW winds will pick up tonight across the local waters and
North Bay and become increasingly gusty across the region into
Monday. For now, even taking the higher side of the deterministic
forecast guidance, we should fall short of reaching Wind Advisory
criteria (35+ mph sustained winds and/or 45+ mph gusts for
elevations below 2500 ft). That said, it will be breezy so make
sure to secure any loose items that might blow about in the
wind. Also remember to do your part to be one less spark given
these conditions. Even though this is a moist onshore flow fine
fuels are curing and fires remain possible (as noted by the ~100
acre Snell fire which popped up in Napa County yesterday).
Remember one less spark, one less wildfire. Otherwise look for
cooler temperatures tomorrow night with lows in the 40s away from
the immediate coast and bays.
&&
.LONG TERM...
(Sunday night through next Friday)
Issued at 1130 AM PDT Sat Jun 17 2023
A cyclonic flow pattern will prevail aloft along the West Coast with
low pressure locating across the Pacific Northwest and NorCal. Gusty
winds will continue on Monday following a cold frontal passage. The
latest deterministic model solutions now develop a closed upper low
in the vicinity of the Bay Area and/or far NorCal on Thursday into
Friday. This should strengthen the onshore flow yet again and result
in a deeper marine layer. Global Ensembles are hinting at some light
(trace to barely measurable) precipitation during this time, but no
real impacts expected regardless. Temperatures will remain near to
below normal with no heat waves to speak of on the horizon.
&&
.AVIATION...
(00Z TAFS)
Issued at 543 PM PDT Sat Jun 17 2023
Surface pressures are lowering across the cwa while the northerly
pressure gradient ACV-SFO is steadily increasing, 00z (5 pm) it`s
4.8 mb, approx 1 mb stronger than HRRR and NAM output. Embedded
within the northerly pressure gradient is a moderate southerly
gradient 1.1 mb STS-UKI. The SFO-SAC pressure gradient is 3.2 mb.
Northwest winds and steady cool air advection is forecast in the
lower levels of the atmosphere tonight through Sunday, deepening
and weakening the marine layer temperature inversion, the marine
layer temperature inversion will mix out by Sunday afternoon or
early evening. A stronger push of cooler air arrives Sunday night
into Monday morning.
Near term forecast challenges include areal coverage and extent of
inland intrusion of stratus /MVFR-IFR/ this evening, as mentioned
the northerly gradient (and wind) overall is a little stronger than
mesoscale models predict; this favors stratus staying over the coastal
waters. Monitoring the ACV-SFO pressure gradient, if it exceeds ~ 6
mb an old rule of thumb is stratus stays confined to the coast with
limited inland extent (improves chances SFO remains VFR). The diurnal
influences added to the current synoptic pattern e.g. normal weak
background downturn in surface pressures because of solar surface
warming will wane by mid evening with surface temperatures cooling
under onset of night-time radiational cooling and aforementioned
cool air advection. Appreciable lower level cool air advection of
a few to several degrees Celsius takes place tonight through Sunday,
the stratus becoming subject to erosion through increasing vertical
mixing with the loss of the marine layer temperature inversion. The
stratus will most likely fully mix out Sunday /VFR/. Otherwise gusty
northwest to west winds are in the cards Sunday. It may be close
to Airport Weather Warning criteria (sustained and/or gusts to 35
knots or stronger) at SFO briefly this evening and again Sunday.
Vicinity of SFO...Strengthening ACV-SFO pressure gradient and wind
raises confidence VFR prevails tonight, however not quite there
yet with ACV-SFO 4.8 mb, needs to be somewhat stronger. Mesoscale
models are under-forecasting the ACV-SFO pressure gradient thus
leaning toward better chances VFR tonight than not, question is
will there be a short influx of stratus this evening just as cool
air advection is beginning (combined with late day diurnal land vs
ocean surface temp contrasts, press gradient). HREF is leaning to
VFR, adds confidence to VFR forecast. Visible imagery still showing
stratus pooling to the northwest of Point Reyes, still have a ways
to go yet this evening. Winds, observations show an uptick in
winds both at SFO and OAK with recent peak gusts to ~ 30 knots.
Will closely monitor through evening for any additional increases
in wind. Otherwise more chances of strengthening wind Sunday with
the mid-latitude pattern settling across the Bay Area (and north
Central Coast).
SFO Bridge Approach...Moderate to high confidence VFR.
Monterey Bay Terminals...Varying stratus coverage early this evening,
the Fort Ord profiler shows a compression in the marine layer in the
last 2-3 hours, in response to a peak in lower level thermal ridging
forecast by the mesoscale models. Otherwise steady northwest winds
and additional stratus will converge along the coast with MVFR-IFR
ceilings forecast for early to mid evening through late tonight.
MVFR-IFR stratus ceilings mixing out to VFR Sunday due to widespread
strong lower level cool air advection and returning diurnal mixing.
&&
.MARINE...
(Tonight through next Thursday)
Issued at 449 PM PDT Sat Jun 17 2023
Strong and gusty northwesterly winds will develop into the evening
tonight, and look to last until Tuesday as troughing develops.
Windiest spots continue to be between Point Arena and Point
Reyes, as well as south of Point Sur, where occasional gale force
gusts are possible. As a result of strong winds, hazardous water
conditions are expected Sunday and Monday due to steep wind-
driven waves. In addition, afternoon and evening gusty winds are
forecast each day across the San Francisco Bay mainly north of the
Bay Bridge to the Delta. Longer period southerly swell continues
alongside shorter period and light northerly swell.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 AM PDT Monday for PZZ530-575.
Small Craft Advisory from 9 AM Sunday to 3 PM PDT Monday for
PZZ535.
Gale Watch from Monday afternoon through Monday evening for
PZZ535.
Small Craft Advisory until 9 AM PDT Sunday for PZZ540.
Gale Watch from Sunday morning through Monday evening for PZZ540.
Small Craft Advisory until 3 PM PDT Sunday for PZZ545-570.
Gale Watch from Sunday afternoon through late Sunday night for
PZZ545-570.
Small Craft Advisory from 3 AM Sunday to 9 AM PDT Monday for
PZZ560.
Small Craft Advisory from 9 PM this evening to 3 PM PDT Sunday
for PZZ565.
Gale Watch from Sunday afternoon through Monday evening for
PZZ565.
&&
$$
SHORT TERM...SPM
LONG TERM....SPM
AVIATION...Canepa
MARINE...AC
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Area Forecast Discussion
National Weather Service Springfield MO
921 PM CDT Sat Jun 17 2023
...Mesoscale Discussion...
Key Messages:
1. Storm complex will move through the area tonight. Wind gusts up
to 65 mph, hail up to the size of quarters, and locally heavy
rainfall are the primary hazards.
2. Showers and thunderstorms linger into Father`s Day; most
widespread east of the Hwy 65 corridor.
3. Warmer and mostly dry next work week.
.MESOSCALE DISCUSSION...
Issued at 821 PM CDT Sat Jun 17 2023
Severe convection has developed as expected from western Kansas
into the Texas Panhandle. This activity is quickly growing
upscale into a mesoscale convective system (MCS) given a high CAPE
environment favoring aggressive cold pool conglomeration.
Given the highly unstable environment ahead of this MCS (MUCAPEs of
3000-4000 J/kg), it will likely follow forward propagating
Corfidi vectors. Confidence is therefore high that this activity
will advance east across southern Kansas and northern Oklahoma
throughout the remainder of the evening with perhaps a slight turn
to the east-southeast into higher instability. This will include an
attendant threat for 60-75 mph winds.
As this MCS (squall line) begins to approach extreme southeastern
Kansas and the I-49 corridor around 1 AM, it is expected to begin
a gradual decaying phase. However, the initial decaying stages of
an MCS often feature a mesoscale rear inflow jet descending
towards the surface. Thus, we believe that wind gusts of 50-65 mph
are plausible generally southwest of a Stockton to Springfield to
Theodosia line as this squall line moves east across that region
through the 3 AM time frame. Potential wind speeds should then
drop off farther east across the Missouri Ozarks as the MCS
continues to decay during the predawn hours.
Other potential hazards with this MCS will be hail to the size of
quarters and locally heavy rainfall. As mentioned in the previous
AFD, the 12Z HREF localized probability matched-mean product
indicated isolated pockets of rainfall in the 3-4" range. The last
several runs of the HRRR have maintained local pockets of 2-3"
amounts. If the higher-end values do indeed indeed pan out, there
would be a localized flash flooding risk.
Given that the cold pool with this MCS will be outflow dominant
(owing to weak low-level shear), the threat for tornadoes looks
almost non-existent.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 107 PM CDT Sat Jun 17 2023
Water vapor imagery showed an upper-level trough axis centered
over Colorado early this afternoon. This wave will provide the
impulse for MCS development this afternoon and evening across the
Plains as it pushes eastward. Storms likely begin to enter far
southeastern Kansas and western Missouri shortly after midnight
tonight. Mid- level lapse rates of 8 C/km will produce moderate to
strong instability of 2000-3000 J/kg across our southwest CWA.
While the best shear looks to be west and south of our area closer
to the subtropical jet, 0-3 km bulk shear values of 20-30 kt
should aid in storm organization across our southwestern CWA.
These ingredients could allow for hail up to the size of quarters
and straight line wind gusts up to 60 mph. Storms look to outrun
the better instability as they push east through our area, so
expecting a weakening trend overnight.
The other hazard with this activity will be localized flash
flooding. High precipitable water values near the 90th percentile
relative to climatology are supportive of efficient rain rates.
The 12Z HREF Localized Probability Matched-Mean (which is
typically a good indicator of reasonable high-end rain totals)
shows pockets of 3-4 inches of rainfall into Sunday morning. One
mitigating factor is that storm motion looks to be fairly quick,
so the dwell time of a heavy downpour over any given location
should be short. However, will still have to monitor for localized
flash-flooding where rainfall rates are high.
Showers and thunderstorms look to linger into Sunday. The most
widespread coverage looks to be along and east of the Highway 65
corridor, with the activity being more scattered in nature to the
west. There is a low chance for a strong to severe storm or two
given marginal shear and instability; however, confidence is low
as it will likely be conditional on tonight`s activity.
Temperatures Sunday will be a bit cooler, with highs in the upper
70s to low 80s.
.LONG TERM...(Sunday Night through Saturday)
Issued at 107 PM CDT Sat Jun 17 2023
Storms largely look to move out of the area Sunday evening. Kept low-
end rain chances across the eastern Ozarks and south-central
Missouri into Monday as the upper-level waves stalls out and cuts
off a low pressure center across the Tennessee Valley, but most
of the day and most of the area looks dry.
Ensemble guidance then shows a high amplitude ridge building
across the central US, which will bring warmer than normal and
mostly dry conditions to the area through the work week. NBM
temperature spreads suggest daily highs in the mid 80s to low 90s
each day, with overnight lows in the 60s. More uncertainty is
introduced into the forecast by next weekend as model guidance
begins to significantly diverge.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 612 PM CDT Sat Jun 17 2023
Strong to severe convection possible late tonight, currently
occurring in western Kansas into the Oklahoma panhandle. This
activity is expected to continue shifting east and should move
into the area generally by 05z and continue through the remainder
of the night. Outside of the convection, we are expecting VFR
conditions, but will likely see flight conditions worsen in the
convection to MVFR and IFR. Also, variable wind gusts of 30 to 50
kts will be possible in the strongest storms. Best timeframe for
convection: SGF 7-11z, JLN 5-10z and BBG 8-12z. Some redevelopment
will be possible in the eastern Ozarks by late morning and
afternoon and have included a prob30 group for BBG for this
possibility.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
MESOSCALE...Schaumann
SHORT TERM...Didio
LONG TERM...Didio
AVIATION...Lindenberg
Area Forecast Discussion
National Weather Service Shreveport LA
345 PM CDT Sat Jun 17 2023
...New SHORT TERM, LONG TERM...
.SHORT TERM...
(This evening through Sunday Night)
Issued at 342 PM CDT Sat Jun 17 2023
It`s been a very long week for everyone, and it looks like the
ArkLaTex is in for two more rounds of severe weather before this
marathon is finally over. Additionally, much of the region will
continue to experience oppressive heat indices this weekend and into
early next week.
Beginning this evening, the first complex of thunderstorms will
organize along the Texas-Oklahoma border and propagate eastward into
the Four State Region as midnight approaches. Depending on the
forward speed of this initial line, the opportunity may exist for
interaction with steep lapse rates in the vicinity of 8.0 deg C/km.
If this transpires, large hail may be a concern. The 18Z HRRR drives
this first line across the northern ArkLaTex overnight, passing
through the Texarkana metro circa midnight and continuing across
southern Arkansas into the small hours of the morning.
While this is taking place through the late overnight and very early
morning hours, another cluster of thunderstorms will simultaneously
be organizing in south central Oklahoma into north central Texas. As
daybreak Sunday approaches, this cluster looks posed to spread into
a large squall line oriented from northwest to southeast, reaching
extreme southeastern Oklahoma possibly as soon as 09Z or 10Z and if
forward speed is sufficient, reaching the Shreveport-Bossier metro
early tomorrow morning. Concurrently, in the wake of the departing
first system, additional convection looks to fire up along the
Louisiana-Arkansas border ahead of the second line during the
morning Sunday.
As the second system pushes into the region overnight, a large swath
of surface to 500 mb bulk shear values in excess of 50 kts will push
south and east over the Four State Region on northwest flow aloft.
If this shear mixes down to the surface, damaging winds may prove to
be a significant concern across much of the region, in addition to
the threat of large hail and a tornado or two.
The HRRR depicts an aggressive solution pushing the majority of the
convection out of the SHV CWA as soon as lunchtime Sunday. The
consensus is somewhat more reserved, however, and also suggests a
slight chance of further storms across the southern half of the
region through the afternoon and early evening Sunday, gradually
clearing the area from west to east overnight as Monday morning
approaches.
Regarding precise timing solutions, it is important to remember that
one model doesn`t necessarily tell the whole story, and the entire
Four State Region should be prepared for multiple rounds of severe
weather beginning this evening and continuing for much of the day
Sunday.
On top of the above, persistent heat and oppressive humidity look to
continue to combine to make heat indices an additional hazard
through the weekend. Extremely high dew points this afternoon
motivated the upgrading of the Heat Advisory to an Excessive Heat
Warning along much of the I-20 corridor as far east as Webster
parish, and at least the Advisory will likely need to be extended
through the overnight hours once again. Lows in the upper 60s north
to upper 70s south will make for another warm, muggy night which
looks to repeat itself Sunday night into Monday morning. Highs
Sunday are currently forecast to again climb into the upper 80s
north to upper 90s south, with heat indices above 105 looking likely
once again.
/26/
&&
.LONG TERM...
(Monday through next Friday)
Issued at 342 PM CDT Sat Jun 17 2023
During the day Monday, an upper level ridge will build centered over
the Upper Great Lakes and it`s trailing axis southward across the
Plains and to the Big Bend of Texas. South of the ridge, an upper
trough will become cutoff. Together, this will form a Rex Block that
will generally come to dominate our weather until the end of the
week. Hot and humid conditions will persist Monday and Tuesday
likely resulting in more Heat Advisories and Excessive Heat
Warnings. Tuesday will likely be the worst day in terms of the heat,
as compressional warming ahead of a backdoor cold front should add
at least a couple of degrees more to daytime highs. Several
locations in Deep East Texas may see afternoon highs about the
century mark, and much of East Texas may have peak heat indices
above 110 degrees F.
We should finally begin to see relief Wednesday and Thursday as
cooler and drier air advect into the region from the northeast in
the wake of the aforementioned cold front. There is a great deal of
uncertainty how far southwest the cooler air will intrude. Portions
of East Texas and the Lower Toledo Bend Region may remain in the mid
to upper 90s, but locations along and north of Interstate 20 should
only be in the upper 80s to near 90 degrees F. However, the Rex
Block will break down and the upper trough will retrograde over the
region. Rain chances during the long-term period will generally be
limited to isolated diurnally-driven convection in the southeast
half of the area. However, PoPs will diminish as deep layer moisture
continues to wane. As we dry out and maintain abundant sunshine,
temperatures will climb back into the mid to upper 90s by next
weekend.
CN
&&
.AVIATION...
(18Z TAFS)
Issued at 1235 PM CDT Sat Jun 17 2023
For the 17/18Z TAFs, patches of MVFR cigs continue to prevail at
most area terminals, with some lifting to lower end VFR through
the afternoon. Winds of 5 to 10 kts will trend from the southwest
through the afternoon and early evening. By 03Z, a system of
storms will enter ArkLaTex airspace, progressing east through the
night and continuing into Sunday morning, particularly north of
I-20. Prevailing VCTS for impacted terminals. Reductions in
vis/cigs The advance of these storms will be accompanied by
variable gusty winds of up to 20 kts with locally higher gusts
expected overnight and into Sunday with the strongest storms.
/26/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 76 95 74 96 / 40 30 30 0
MLU 73 92 73 93 / 30 50 50 10
DEQ 67 87 66 94 / 70 50 10 0
TXK 71 91 70 95 / 60 50 20 0
ELD 69 90 69 92 / 60 50 40 0
TYR 76 96 74 97 / 30 20 20 0
GGG 76 95 73 97 / 30 30 20 0
LFK 77 97 75 100 / 10 20 20 0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...Excessive Heat Warning until 8 PM CDT this evening for
LAZ001>003-010>012-017>020-022.
Heat Advisory until 8 PM CDT this evening for LAZ001>006-010>014-
021.
OK...None.
TX...Excessive Heat Warning until 8 PM CDT this evening for
TXZ124>126-136>138-149>153-165>167.
Heat Advisory until 8 PM CDT this evening for TXZ108>112-124>126-
136>138-150-151.
&&
$$
SHORT TERM...26
LONG TERM....09
AVIATION...26
...Update to aviation forecast discussion...
.DISCUSSION...
Issued at 240 PM CDT Sat Jun 17 2023
Key points:
* Thunderstorms remain possible through Sunday morning with small
chances for severe storms and locally heavy rain
* Above normal temps next week with minor precip chances
Kansas is between three areas of upper level vorticity early this
afternoon -- the main one moving east across central Colorado and
others moving northeast out of eastern Nebraska and east over
southwest Missouri. A weak frontal boundary was subjectively
analyzed over central and southwest portions of Kansas at 17Z with
very weak convergence along it. RAP sounding showing some convective
inhibition still in place across much of the local area.
There remains some potential for thunderstorms to form locally along
the weak boundary as the boundary layer warms this afternoon, though
forcing for ascent is hard to come by beyond the weak boundary.
Recent HRRR runs have steadily diminished coverage of weak/brief
convection. Have kept chance pops in the most likely areas in
northeast and east-central Kansas. MLCAPE around 1500 J/kg and
deep-layer shear around 30 knots bring minor potential for severe
storms from hail and wind. The greater coverage of storms is
still on track for the late evening into post-dawn hours as a
convective complex forms in southwest Kansas and tracks east. With
the accompaniment of the upper wave, storm chances overspread the
entire area with the greatest chances for storms in the south.
MUCAPE remains around 1500 J/kg and could support a minor severe
storm risk again in hail and wind. There is also some potential
for a few hours of precip and with PWs around 1.5 inches, locally
heavy rains are possible. The MCS and upper wave exit by midday
Sunday.
An upper level ridge steadily builds northeast from the southern
Rockies/High Plains northeast into the Great Lakes next week. Many
dry periods are likely though central High Plains convection could
spread this far east at times. Overall a warmer and slightly humid
forecast is in order with 850 mb temps around 20 C.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 615 PM CDT Sat Jun 17 2023
VFR at all TAF sites through the TAF period. Showers and
thunderstorms are possible before 05z this evening, but confidence
in any forming is too low to mention in the TAF. A complex of
showers and thunderstorms is moving into western Kansas at this
moment. This complex will track eastward across the state this
evening. The most likely time of arrival for our area is between
05z and 08z. The bulk of thunderstorms associated with this
complex will likely stay south of the terminals, but enough could
make into the Topeka area that a vicinity mention seemed prudent.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...65
AVIATION...Jones
Area Forecast Discussion
National Weather Service Tulsa OK
945 PM CDT Sat Jun 17 2023
...New SHORT TERM...
.SHORT TERM...
(The rest of tonight)
Issued at 925 PM CDT Sat Jun 17 2023
Bottom line up front...looks like a long and active night for
much of the forecast area in terms of severe weather potential.
Presently there are two zones of ongoing severe weather that will
begin to impact parts of eastern OK within the next few hours.
First, an expanding linear complex moving across northwest OK,
with a history of 60-80 mph gusts. This will continue to move ESE
toward northeast OK and given the thermodynamic environment in
place, will sweep through northwest AR late tonight. Second, a
cluster of somewhat more discrete convection moving int o south
central OK, near region or upper diffluence. This should continue
to organize over the next few hours into another complex which
will move across southeast OK.
Still some question remaining regarding the possible interaction
of these two complexes, but recent trends seem to show that the
southern one will outpace the northern one enough that both will
offer potential for swaths of high-end damaging wind gusts and
perhaps hail as well. There does remain potential for embedded low
level rotation within these lines of storms as well, as the HRRR
has been suggesting some interaction between the NE OK complex and
a subtle low level boundary lifting north across eastern OK.
These above mentioned storms will exit the CWA around 2-3 AM, but
that might not be the end as a consistent signal remains that
additional storms could develop late tonight across
central/western OK and organize into another complex, which would
move across SE OK around 10-12z.
Forecast will be updated to raise POPs in the immediate term
across far southeast OK, otherwise no substantial changes to the
forecast or the overall messaging.
&&
.LONG TERM...
(Tomorrow through Saturday)
Issued at 228 PM CDT Sat Jun 17 2023
Storms will likely be ongoing Sunday morning, especially across
far E OK and NW AR. Severe weather potential will be lower at that
time. Most activity will be east of the area after 18z, but will
keep lower PoPs between 18z-21z. Upper ridging begins to take
shape over much of the central CONUS next week which will result
in warmer temperatures. Developing low pressure systems across the
PAC NW and SE results in the upper ridge becoming elongated with
a more SW-NE orientation. Late in the week, weak upper level
disturbances moving across the top of the compressed ridge may
offer low chances for showers and storms during that time, but
will largely keep a dry forecast beyond Sunday.
&&
.AVIATION...
(00Z TAFS)
Issued at 636 PM CDT Sat Jun 17 2023
Severe convection currently ongoing from wrn KS through the
Panhandles into nwrn TX. Activity is expected to organize into one
or two lines as it approaches ern OK late this evening, and nwrn AR
shortly after midnight. IFR conditions and possible severe wind
gusts will accompany the initial line. Attempted to time TEMPO groups
to most likely window at each site, then carried PROB30 groups for a
few hours afterwards to account for lingering activity as MCS moves
through the area. Thunderstorm chances end from west to east early
Sunday morning ern OK to late morning nwrn AR. MVFR ceilings likely
to develop Sunday morning at all sites, and persist into the
afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 67 85 65 93 / 80 30 0 0
FSM 71 85 67 93 / 80 60 10 0
MLC 68 87 64 94 / 70 40 0 0
BVO 63 85 61 93 / 80 30 0 0
FYV 64 80 62 90 / 80 60 10 0
BYV 65 79 62 88 / 80 70 10 0
MKO 67 84 64 91 / 80 40 0 0
MIO 65 82 63 91 / 80 50 10 0
F10 66 84 64 91 / 80 30 0 0
HHW 69 87 66 92 / 70 40 0 0
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...14
LONG TERM....23
AVIATION...69