Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/21/24
See below for an aviation forecast discussion for the 00Z TAFs.
&&
.SHORT TERM /THIS EVENING THROUGH FRIDAY NIGHT/...
Issued at 245 PM CDT Thu Jun 20 2024
Precipitation has remained mostly south of Hwy 212 so far today.
There are a few showers showing up on radar farther north, but the
bulk of the activity remains closer to the primary boundary - a
developing warm front stretching east northeast from a Colorado low
across northern NE. A 30 to 40kt llj in the warm sector and some
ample shortwave activity riding the upper ridge will help kick off
some strong to severe thunderstorms through this evening. However,
the strongest part of the jet looks to remain across NE and maybe as
far north as the NE/SD border. A more anemic 20 to 25kt llj may push
into central and east central SD. Weak convection with heavier rain
is the most likely scenario tonight, but there is a marginal to
slight risk (1 to 2 out of 5) for severe storms south of Hwy 14.
Anything severe could be more likely if an MCS traverses out of
Wyoming and the Black Hills and clips this forecast area with strong
winds.
WPC pushed a moderate risk for excessive rainfall into Lyman and
Buffalo counties for tonight. Given the convection, chances for
locally heavy rainfall are present, especially with PWATs a full
standard deviation above normal. Could still see an additional 1 to
3 inches of widespread rain across the southern cwa into east
central SD through Friday night with embedded areas of more intense
accumulations. Therefore, issued a flood watch through Friday night
due to the wetter antecedent conditions and thunderstorm potential.
The warm front will stretch farther northeast on Friday and be the
focus point for strong to severe storms. The timing has really
waffled on storm development but could be as early as 17z or closer
to 21z. There is a slight risk for severe storms along and south of
Hwy 212 Friday. Less sold on anything much developing too far north
of the front, but there is a low potential for a couple of tornadoes
right on the front aside from risks of strong winds and large hail.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 245 PM CDT Thu Jun 20 2024
Saturday starts the long term with a shortwave over the area. This
will move east fairly quickly before a ridge builds in for Sunday.
This ridge stays over the region a little longer than in previous
model runs, lasting at least into Monday afternoon before we
transition to more westerly/zonal flow. Tuesday a quick shortwave
makes its way across the area. Another ridge starts to build in for
the end of the period.
We start the long term with some possible lingering showers over far
northeastern SD and west central MN Saturday morning. Monday evening
is going to be our next chance for some rain ahead of that shortwave
trough. Chances are pretty limited, with highest being 25 to 35%
over eastern SD and west central MN. Accumulations are also expected
to be low, toping out at about a tenth of an inch over east central
SD.
Temperatures to start the period will be warming, peaking on Monday
with highs east of the James River about 5 to 10 degrees above
average and west of the James River about 10 to 15 degrees above
average. Highs return to about average for the rest of the period.
Winds are expected to be around normal for the entire period.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 622 PM CDT Thu Jun 20 2024
Terminals KABR,KATY,KPIR,KMBG
A blanket of clouds is over the region. Prevailing conditions are
characterized as generally MVFR or lower. Guidance indicates that
later tonight after 06Z, the prevailing condition at all four
terminals will drop into some form of IFR (cigs) and remain there
until sometime later on Friday when some improvement is expected.
With the current batch of showers and thunderstorms just about
done affecting terminal airspace, it appears that there will be a
several hour break before more showers/thunderstorms begin picking
up/moving in from the southwest later this evening into the
overnight hours. Keeping an eye out for heavy rainfall, which
could lead to reduced (MVFR/IFR) visibility overnight.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Flood Watch through Saturday morning for SDZ018>020-022-023-036-
037-048-051.
MN...None.
&&
$$
UPDATE...Dorn
SHORT TERM...Wise
LONG TERM...KK
AVIATION...Dorn
Area Forecast Discussion
National Weather Service La Crosse WI
1050 PM CDT Thu Jun 20 2024
.KEY MESSAGES...
- Multiple rounds of heavy rain are expected Friday morning
through at least Saturday morning. How the bands line up will
determine the local flooding threat. Confidence is lower on
exactly how the later storms Friday night into Saturday
afternoon evolve.
- A few storms Friday and Saturday may be severe, with damaging
winds the main threat.
- A brief respite from the active pattern for Sunday and Monday,
but more storms loom for Monday night into Tuesday.
Unfortunately, severe storms cannot be ruled out for Monday
night into Tuesday.
&&
.UPDATE...
Issued at 1040 PM CDT Thu Jun 20 2024
With the evening update, in coordination with MPX have an
earlier start time to the Flood Watch for flash flooding.
The 03Z surface from stretched from central Iowa into northern
Kansas with surface dewpoint in the 70s south of the front. The
warm front is forecast to slowly lift north Friday. Overnight, a
convective complex over parts of Nebraska/South Dakota is
forecast to push east across MN with storms reaching our
southeast MN counties in the morning. Precipitable water values
increase 150 to 200 percent along and north of the frontal axis.
The storms are forecast to move around 20kt, however due to the
continue moisture transport/theta-e advection/low level jet,
training of storms is expected and these morning storms may put
down some locally heavy rain. The CAMs still have some
differences in how far north the heavy stripes of rain will be
Friday morning. The 21.00Z HREF has the mean heavy rain more
from RST toward north of LSE. However, should the warm front not
make it as farther north, the heavy would likely affect areas
farther south. See our detailed river flood products for updates
as we head into this significant rain/river flood event.
&&
.DISCUSSION...
Issued at 338 PM CDT Thu Jun 20 2024
This Afternoon into Tonight: Decreasing Potential for Thunderstorms
Largely as expected, widespread cloudiness across much of the CWA
has limited surface insolation, with latest RAP guidance suggesting
less than 250 J/kg of MLCAPE is present and, with winds out of the
east, am not expecting robust enough low level warm advection to
change this. Have therefore continued to limit mentions of thunder
to 30 percent or less. Additionally, with 18z WV satellite showing
the CWA is largely between two shortwaves - one southeast of the CWA
and the second looking to pass just to our northwest, much of the
area looks to remain free of precip entirely, with the exception of
areas along an Albert Lea MN to Medford WI axis, where the close
approach of the northwestern shortwave should be enough for at least
a few showers. In either case, am not too concerned about excessive
rainfall with any showers this afternoon and evening given PWAT
values are generally under 1.65" and 700/850mb moisture transport is
modest.
Friday through Saturday: Heavy Rain, Flooding, and Severe Storm
Potential
This evening, moisture transport increases markedly over the central
High Plains ahead of an advancing upper trough. As a shortwave
ejects over NE, an MCS should develop and translate east-
northeastward along a northward lifting warm front to SD and
eventually S MN by Friday morning. As for severe thunderstorms, this
morning MCS could pose an isolated damaging wind threat in S MN if
it remains sufficiently organized. Finally, flood threat with this
initial rounds appears to be low as 700/850mb moisture transport
remains modest for this initial round.
Friday afternoon and evening, low level moist advection should help
MLCAPE build to 1000-1500 J/kg as the front, forced southward by the
morning MCS, pushes back northward. While 0-6km bulk shear values
are generally 35 knots or less, this would be sufficient for perhaps
a bit of organized convection. While hodographs are not overly
impressive, if enough surface destabilization can occur, there would
be at least a small probability for all hazards with damaging winds
having the higher relative risk. The primary concern with this
activity will be heavy rainfall and flooding as 700/850mb moisture
transport will increase in time as the main upper trough advances
eastward over the central Plains and becomes oriented out of the
southwest, somewhat along the expected east-west axis of the front.
PWAT values look to top 2 inches, with these values exceeding the
99th percentile in both the NAEFS and ENS climatology. Thus,
expect efficient rain producers with some areas potentially affected
by training storms. Given this and the saturated soils from abundant
recent rainfall, have issued a Flood Watch beginning Friday
afternoon.
Main uncertainty Friday afternoon focuses on how far north the low
level warm advection pushes the front after it is forced southward
by outflow from the morning MCS. Non-CAM guidance suggests the
boundary may return to a position just northwest of our CWA while
many CAMs have trended toward a solution roughly around Interstate
90. While all guidance tends to struggle with the effects of cold
pools, am inclined to learn toward the CAM solutions as they tend to
do a bit better. Have therefore trended axis of highest QPF to the
south and this adjustment may not yet be enough. Second uncertainty
focuses on the timing of the morning MCS - should this arrive
sufficiently late, this round could carry a higher risk for severe
wind as the morning inversion breaks. Additionally, this would delay
airmass recovery and onset of the second round of storms.
Moving ahead to Saturday morning, our third round of convection
looks to occur as the main upper trough finally approaches. As moist
advection continues, PWAT values approach NAEFS/ENS climatological
maximums and training risk increases as 850mb moisture transport
becomes more oriented along the surface boundary. Have therefore
kept the Flood Watch going through midday Saturday.
The already high uncertainty in details increases markedly by
Saturday afternoon. Should the previous three rounds of convection
occur largely as envisioned, the boundary may very well be shunted
southeast of the CWA for good. Given this uncertainty, have ended
the Flood Watch early Saturday morning. If the boundary remains in
our CWA, would need to extend this Watch in time. Finally, if the
boundary remains in our CWA, destabilization to the south of this
feature Saturday afternoon would lead to another period with severe
thunderstorm potential. Given the modest increase in deep shear as
mid to upper level flow ramps up ahead of the upper trough, all
severe hazards could be in play in the southeastern third of the CWA
if this fourth round manifests itself.
Sunday through Wednesday: Brief Break from Storms, then Active
Weather Returns
In the wake of Saturday`s upper trough, northwesterly flow aloft
begins to dominate proceedings. With conditions at 700/850mb drying
out considerably, most areas should remain free of rain Sunday, with
the exception of north central Wisconsin due to a passing upper
wave. Next wave Monday night into Tuesday may bring additional
rainfall with CSU ML severe outlooks suggesting at least some risk
for severe thunderstorms during this period. Admittedly had little
time to closely examine this given the abundance of active weather
in the short term but will need to keep an eye on Monday and
Tuesday.
&&
.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 955 PM CDT Thu Jun 20 2024
Increasingly challenging Aviation forecast. In the nearest term,
upstream observations have varied between LIFR and VFR with
thunder slowly trudging east through central Minnesota late
tonight. Has been drastically slower with every radar loop
however. Confidence increases through Friday for precipitation
moving west to east. Confidence remains low on exact location
of heaviest rainfall and convective storms. Therefore, have
continued VCTS at both TAF sites but needs further refinement as
forecast hour nears.
&
.HYDROLOGY...
Issued at 405 PM CDT Thu Jun 20 2024
A Flood Watch has been issued for parts of southeast Minnesota,
northeast Iowa, and western Wisconsin from Friday into Saturday.
Multiple rounds of heavy rain are expected from Friday morning
through Saturday, increasing the potential for flash flooding.
Widespread rainfall accumulation of 2 to 4 inches is forecasted
with locally higher amounts exceeding 5 inches possible in
spots. Highest flash flooding risk remains dependent on exact
location of heaviest rainfall bands. Should the heaviest
rainfall bands line up over the smaller river basins, there is
a 20-30 percent chance that these basins could experience
periods of flooding at moderate flood stage.
Additionally, the combination of recent heavy rains with the
ongoing rounds of storms increase river flooding potential into
next weekend. Moderate to high confidence (60-90% chance) for
sites along the Mississippi River to exceed flood stage during
this time.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Flood Watch from 7 AM CDT Friday through Saturday afternoon
for WIZ032.
MN...Flood Watch from 7 AM CDT Friday through Saturday afternoon
for MNZ079-086>088-094>096.
IA...Flood Watch from 7 AM CDT Friday through Saturday afternoon
for IAZ008>011-018-019.
&&
$$
UPDATE...Zapotocny
DISCUSSION...Ferguson
AVIATION...JAR
Area Forecast Discussion
National Weather Service Boston/Norton MA
1002 PM EDT Thu Jun 20 2024
.SYNOPSIS...
Scattered strong to severe thunderstorms remain possible this
evening...mainly across northern MA where a Severe Thunderstorm
Watch is in effect. A backdoor cold front moves in from northeast to
southwest Friday...bringing another round of showers and
thunderstorms. The bulk of this activity should be across interior
Massachusetts and Connecticut...where some of the storms may become
severe and also result in a localized flash flood threat. Warm
and muggy this weekend with rain and thunderstorm chances both
Saturday and Sunday. A cold front sweeps across the region Monday
with additional showers and storms, briefly less humid on Tuesday,
but summer warmth and humidity returns for midweek.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
10 PM Update
The severe thunderstorm threat has ended with storms loosing
strength very quickly after sunset as capping inversion
developed. A few lightning strikes are still being observed,
mainly over the waters, but more stratiform showers have become
the more dominant precipitation mode over the last hour or so.
We expect that showers will continue to dissipate over the next
two to three hours, with dry conditions expected well before
sunrise.
Given the lack of instability/forcing after sunset, the Severe
Thunderstorm Watch has been cancelled.
Previous update...
745 PM Update
* Strong to Severe T-Storms through late evening in areas north
of the CT/RI/MA State lines
* Localized damaging wind gusts & torrential rainfall which may
result in a very localized flash flood threat
Shortwave energy across northern New England coupled with
outflow and MLCapes still over 2000 J/KG has resulted in a
solid line of strong to severe t-storms to enter northwest and
northern MA early this evening. We think enough outflow will
result in a risk for severe storms over the next 1-3 hours in
areas at last north of the CT/RI/MA state lines. This is also
supported by the latest machine learning probs from the CSU to
the Nadocast and HRRR Neural network...which are all showing a
quite robust signal for localized damaging wind gusts. Main
question is how far south this convection will survive as it
out-runs the greater forcing. Given that DCapes are still over
1000 J/KG...we expanded the Severe T-Storm Watch to the CT/MA
border and extended it through 11 pm. Also...these storms will
be capable of producing torrential rainfall and a localized
flash flood threat.
Once this activity winds down later this evening...much of the
overnight hours should feature dry/muggy weather. Overnight low
temps will mainly be in the upper 60s to the lower 70s. We also may
see some patchy ground fog develop overnight given light winds/high
dewpoints especially where rain falls earlier in the evening.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Key Points...
* Showers & t-storms anticipated Fri PM with the severe weather
threat/very localized flash flood threat across interior MA/CT
* Much cooler across eastern MA but still hot & humid towards the CT
River Valley where Heat Advisories remain posted
Details...
Friday...
A backdoor cold front will be moving westward across the region
Friday morning and into the afternoon. This will hold high temps in
the 80s across much of eastern MA and temps along the immediate
coast will probably fall into the 70s by afternoon. Further
inland...high temps will top off in the upper 80s to the lower 90s
with the warmest of those readings in the CT River Valley. The Heat
Advisory for Friday will only cover portions of southwest
MA/CT...where Heat Indices are expected to top off between 95 and
100 degrees.
The other concern will be for another round of showers & t-
storms...which looks to be Friday afternoon/early evening. The focus
for this will be along the backdoor cold front and will be enhanced
by shortwave energy in west to northwest flow aloft. While a few
showers & t-storms may impact the entire region...thinking the main
focus for the potential of severe weather/localized flash flooding
will be across western/central MA & northern CT. This is where the
greater instability will reside on the order of 1500 to 2000 J/KG.
These backdoor cold fronts can be a recipe for training and a
localized flash flood threat. The CSU Machine learning probs
highlight this risk nicely with again the focus across the interior.
There also is a severe weather risk with the main concerns being
locally damaging wind gusts with hail a secondary risk. This is
depicted nicely by the machine learning probs as well as the HREF
Updraft Helicity Swaths/Radar Simulations.
Friday night...
The convection should dissipate Friday evening. Otherwise...we will
have to watch for areas of low clouds and fog developing. Overnight
low temps will be mainly in the 60s.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Highlights:
* Warm and muggy this weekend with rain chances both Saturday and
Sunday.
* Cold front sweeps across the region on Monday, drier and returning
heat into mid next week.
The mid-level ridge continues to deamplify, as 500mb heights lower
from north to south, which is a consistent theme for the upcoming
weekend. At the surface an area of higher pressure near Bermuda
wanes and surface pressure lowers across the northeast. This area of
low pressure developing over the northern Great Lakes, drives our
weather conditions late this weekend into Monday, as the trailing
cold front, south of the low, sweeps across the northeast sometime
Monday. Beyond Monday, high pressure builds back Tuesday through
Thursday, with a cold front possibly pushing across the region later
on Friday/Saturday.
In addition, most of next week trends warmer than normal, and at
this point, next week doesn`t look to be as extreme as this current
week. Though the ensemble situational awareness tables indicates
Monday through Thursday, surface temperatures could be running
between the 90th and 99th percentile (of climatology), with a return
of average temperatures post cold front, sometime late Friday into
Saturday.
Saturday & Sunday:
Getting closer to home, there is a quasi-stationary frontal boundary
across the region, running from east to west through southern New
England and through Upstate New York on Saturday. Weak area of low
pressure tries to develop along the boundary, with the greatest area
for showers and storms along and north of the Mass Pike during the
mid to late afternoon. At this point, not expecting anything severe,
and SPC has most of the region under general thunder. A slightly
more elevated issue would be the potential for excessive rainfall.
The ERO from WPC highlights much of central/western Massachusetts
and northern Connecticut for a `Marginal` risk. Given PWATs are
above two inches, isolated and locally heavy downpours could lead to
urban street and poor drainage flooding.
Aforementioned frontal boundary becomes a warm front Saturday night
into early Sunday, lifting northeast, and placing us in the warm
sector. Scattered showers into the overnight hours, though the best
forcing appears to be concentrated further north. A prefrontal
trough and shortwave pivot through, with showers and thunderstorms
later Sunday afternoon/evening.
As for temperatures, Saturday will be the `cooler` day, the warmest
location will be the Connecticut River Valley, highs here are in the
mid 80s. Much cooler in northwest Massachusetts where highs are low
to middle 70s with the northeast flow. Nightly lows are still mild
which isn`t ideal for sleeping with windows open, lows are in the
middle to upper 60s to 70 degrees in the Connecticut River Valley on
Saturday night, then 2-4 degrees warmer Sunday night.
Next Week:
Warm and muggy day ahead of a surface cold front with temperatures
climbing into the 80s and dew points in the 60s. Storms develop mid
to late afternoon with the surface cold front, a bit a relief behind
the front with lowering dew points into the 50s and leads to a nice
Tuesday with comfortable, albeit warm day, with dew points in the
upper 50s to 60F. High pressure reestablishes across the northeast
leading to a drier week with return of summer warmth. Highs are in
the middle and upper 80s and lows in the 60s with a sign of cooler
temperatures by late in the week.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
00z TAF Update...
Through 04z This Evening...Moderate Confidence.
Main issue through 04z this evening will be a large cluster of
showers & t-storms. Some of these storms will be strong to
severe and result in locally strong wind gusts and torrential
rain. Still some uncertainty on the southern extent of this
activity...but feel at least areas north of the CT/MA state
lines are the areas of greatest concern.
Overnight...Moderate Confidence.
Mainly VFR once the scattered t-storms wind down by late
evening. However...will have to watch for some patchy ground fog
and reduced vsbys /MVFR-IFR levels/ especially where ground
becomes wet from the earlier showers & t-storms. Light SW winds.
Friday...Moderate Confidence.
Biggest concern is another round of scattered showers &
t-storms. Main risk for a few strong to severe storms will be
across western/central MA & northern CT Friday afternoon/early
evening with locally torrential rainfall. In addition...low
clouds and fog patches may develop during the afternoon/early
evening hours to the east of the CT River Valley. This process
should occur first along the eastern MA coast. Backdoor cold
front will shift the winds to the NE as the day wears along.
Friday night...Moderate Confidence.
Bulk of the scattered showers/t-storms should wind down Friday
evening. Otherwise...light onshore flow and a cooling boundary
layer will allow low end MVFR to IFR conditions to expand
westward during the evening impacting the rest of the region.
KBOS TAF...Moderate Confidence in TAF. Main issue is a cluster
of strong to severe t-storms that will likely be working into
the towards 01z/02z. Based on the latest radar trends and the
environment...we do favor the activity surviving into Boston.
KBDL TAF...Moderate Confidence in TAF. Main concern will be
cluster of showers & t-storms to the north of the terminal. Not
sure if the activity will get that far south...but will need to
be watched 03z/04z.
Outlook /Saturday through Tuesday/...
Saturday: MVFR/IFR conditions possible. Chance SHRA, isolated
TSRA, patchy BR.
Saturday Night: Mainly IFR, with local MVFR possible. Chance
SHRA, isolated TSRA, patchy BR.
Sunday: Mainly VFR, with local IFR possible. Breezy. Chance
SHRA, isolated TSRA, patchy BR.
Sunday Night: Mainly VFR, with areas IFR possible. Breezy. SHRA
likely, isolated TSRA, patchy BR.
Monday: Mainly VFR, with local IFR possible. Breezy. Chance
SHRA, isolated TSRA, patchy BR.
Monday Night: VFR. Breezy. Chance SHRA.
Tuesday: VFR.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight through Friday night...High Confidence.
Nearshore small craft wind gusts will linger from areas near the
southeast New England coast into early this evening...so small craft
headlines continue in this region through 8 pm. Other risk tonight
will be a few strong t-storms which may threaten our northern waters
through about 10 pm. We also will need to watch for some fog
developing overnight.
The backdoor cold front will move across our northern waters Fri
morning...but likely stall across our southern waters Fri afternoon
and night. Pressure gradient will be weak enough to keep winds/seas
below small craft thresholds. We will need to watch for areas of fog
developing during the overnight hours.
Outlook /Saturday through Tuesday/...
Saturday: Winds less than 25 kt. Chance of rain showers, patchy
fog, isolated thunderstorms. Visibility 1 to 3 nm.
Saturday Night: Winds less than 25 kt. Chance of rain showers,
isolated thunderstorms, patchy fog. Visibility 1 to 3 nm.
Sunday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Local rough seas. Slight chance of rain showers,
isolated thunderstorms, patchy fog. Visibility 1 to 3 nm.
Sunday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Rain showers likely,
isolated thunderstorms, patchy fog. Visibility 1 to 3 nm.
Monday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of rough seas. Rain showers likely, isolated
thunderstorms, patchy fog. Visibility 1 to 3 nm.
Monday Night: Winds less than 25 kt. Local rough seas. Chance
of rain showers, isolated thunderstorms, patchy fog. Visibility
1 to 3 nm.
Tuesday: Winds less than 25 kt. Areas of seas approaching 5 ft.
&&
.CLIMATE...
All Time June High Temperature Record (Daily)
BOS - 100 F (06/06/1925, 06/26/1952 and 06/30/2021)
BDL - 100 F (06/26/1952, 06/30/1964)
PVD - 98 F (06/25/1943, 06/15/1945 and 06/30/1945)
ORH - 98 F (06/26/1952)
Most recent day of 100 F (or greater)
BOS - 100 F (07/24/2022)
BDL - 100 F (07/21/2019)
PVD - 100 F (07/28/2020)
ORH - 102 F (07/04/1911)*
* For ORH this is the only 100+ degree day in its period of record.
Daily High Temperature Records...
June 20th
BOS - 98 F (1953)
BDL - 97 F (2012)
PVD - 95 F (1941)
ORH - 93 F (1953)
June 21st
BOS - 96 F (2012)
BDL - 96 F (1953 and 2012)
PVD - 96 F (1941)
ORH - 91 F (Multi-Years)
Daily Warmest Low Temperatures Records...
June 20th
BOS - 78 F (1931)
BDL - 74 F (1931)
PVD - 74 F (1931)
ORH - 72 F (1931)
June 21st
BOS - 80 F (2012)
BDL - 73 F (1923 and 2012)
PVD - 75 F (2012)
ORH - 74 F (1923 and 2012)
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 7 PM EDT Friday for CTZ002>004.
Air Quality Alert until 11 PM EDT this evening for CTZ002-003.
MA...Heat Advisory until 7 PM EDT Friday for MAZ008>011.
Air Quality Alert until 11 PM EDT this evening for MAZ007-
010>021.
RI...Air Quality Alert until 11 PM EDT this evening for RIZ001>005.
MARINE...None.
&&
$$
SYNOPSIS...Frank/Dooley
NEAR TERM...Frank/KS
SHORT TERM...Frank
LONG TERM...Dooley
AVIATION...Frank/Dooley
MARINE...Frank/Dooley
CLIMATE...BL
Area Forecast Discussion
National Weather Service Billings MT
655 PM MDT Thu Jun 20 2024
.UPDATE...
Mostly quiet weather around the forecast area this evening. There
is an area to watch across our north, east of Snowies, thru the
evening. A couple stronger storms developed along the northern
Musselshell and northern Custer county lines over the past few
hours. Brunt of activity has stayed to our north but as ESE low
level jet increases toward sunset would not be surprised to see a
strong to severe storm develop across our northeast (potentially
impacting Forsyth-Miles City-Baker between roughly 02-07z)...
though it should be noted that high res models keep convection to
our north. Otherwise, chance of showers and embedded thunderstorms
will increase from the south overnight as a shortwave emerges
from the southwest flow aloft. Low level easterly winds will
persist, and there will be sufficient elevated instability for
thunderstorm potential along w/ small hail and pockets of heavy
rain during the overnight hours and early Friday. This includes
the Billings metro area. Finally, area of stratus over Carter
County is slowly advecting to the east/north. This will likely
evolve into a stratus/fog combo as the night wears on. In fact,
HRRR suggests 925mb moistening along our western foothills (per
upsloping) by daybreak tomorrow. Something to watch. Overall the
next 12-18 hours are messy, and the showers/stratus/fog will all
have impacts on Friday`s convection. Stay tuned. JKL
&&
.DISCUSSION...
Tonight through Friday night...
Shortwaves and jet energy will move through WSW flow aloft
tonight. With low-level ESE flow, PWAT`s will climb to 1 inch from
KBIL S and E. Some areas showed MUCAPE of 500-1000 J/kg (elevated)
and bulk effective shear around 40 kt tonight. So with enough lift
there could be a few strong storms, mainly along the northern
tier, N of KBIL, where HREF showed a few updraft helicity tracks.
Had 20-30% PoPs much of the night over portions of the area based
on CAMS. Had higher PoPs E of KBIL late at night as second wave
moves through the area. HRRR showed fog, possibly dense, over
Carter and Fallon Counties overnight. Satellite and web cams had
low clouds moving into SE MT. Added areas of fog to the far E
overnight, with patchy fog elsewhere N and E of KBIL. Next shifts
can keep an eye out for possible dense fog advisory. It will be a
warm and humid night with lows well into the 50s.
Stronger trough moves across the area Friday through Friday night.
HREF showed a few helicity tracks S and SE of KBIL Fri. morning.
Helicity tracks become strong in the afternoon with an area of
tracks N of the forecast area and a second area over Sheridan
County and far SE MT. Northern area of tracks weakens as it moves
SE into the forecast area in the evening. MUCAPEs Fri. afternoon
and evening will be 1000-2000 J/kg and bulk effective shear will
be 30 to 50 kt with the strongest parameters from KBIL E and S.
Due to continued ESE flow, some areas showed an inversion on GFS
soundings...so this inversion along with cloud cover could inhibit
strength of some of the storms. High PWAT`s continue which will
bring heavy rainfall with the storms. So, hail, wind and heavy
rainfall will be the threats with any strong to severe storms.
Highest PoPs (50-60%) will be E of KBIL in the morning. 30-50%
PoPs in the early afternoon will increase late in the afternoon
and continue into the evening. PoPs will quickly decrease W to E
late Fri. night. Temps will be in the 70s to low 80s on Friday and
in the 50s Fri. night. Arthur
Saturday through Wednesday...
Upper level ridging will continue to build into the Northern
Rockies through the extended forecast period. Increasing heights
will result in above normal temperatures and mostly dry
conditions. The warmest day in the extended forecast will be
Sunday with highs in the mid 90s, approaching 100F. The
probability of a high temperature of 100F or greater is 20-60%
from Columbus to Busby and Miles City. There is a low chance
(10-25%) for showers and thunderstorms Sunday night as the ridging
is briefly flattened by a weak shortwave. High temperatures for
the rest of the week will be in the mid-upper 80s to mid 90s.
Rivers and streams have fallen considerably over the past week
but still have a bit to go to get down to normal summer flows. If
you head out to the rivers to cool down this weekend be sure to
wear life- vests and continue to use extra caution, especially
with children. Matos
&&
.AVIATION...
Stratus is expected to edge into the area late tonight in Friday
morning with conditions lowering to MFVR. Chances for showers and
thunderstorms increase late tonight, to around 40 percent, over
much of the area E of KLVM and continue through Friday morning
with MVFR/IFR or lower conditions possible in the thunderstorms.
Continued VCSH at KBIL, KSHR and KMLS TAFs for late tonight,
mainly after 06Z. There is a medium chance of seeing a
thunderstorm around KBIL and KMLS in the 12Z to 15Z timeframe as
a 500 mb jet pushes into the area. Isolated to scattered showers
and thunderstorms are possible again Friday afternoon but
confidence is lower during this timeframe with the forecast
depending on how the showers and thunderstorms evolve late tonight
into Friday morning. Wetenkamp
&&
.PRELIMINARY POINT TEMP/POPS...
Fri Sat Sun Mon Tue Wed Thu
-----------------------------------------------------------
BIL 057/079 056/084 059/097 062/091 058/088 058/090 061/093
24/T 31/U 00/U 11/U 10/U 11/U 12/T
LVM 049/080 050/086 054/095 056/090 052/087 053/090 056/089
14/T 21/U 01/N 11/N 11/U 11/U 13/T
HDN 056/081 054/085 057/099 060/092 056/090 057/092 060/096
55/T 41/U 00/U 21/U 10/U 11/U 11/U
MLS 057/078 057/082 058/096 064/089 058/087 058/090 063/093
36/T 51/U 00/U 20/U 10/U 11/U 21/U
4BQ 058/079 057/084 058/097 066/091 059/088 060/091 063/094
46/T 41/U 00/U 10/U 10/U 11/U 11/U
BHK 054/075 054/080 054/092 061/088 055/085 055/086 057/089
26/T 51/B 00/U 10/U 11/U 11/U 12/T
SHR 052/080 051/083 055/097 061/092 055/087 056/091 059/093
37/T 31/U 00/U 10/U 10/U 11/U 11/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Columbia SC
813 PM EDT Thu Jun 20 2024
.SYNOPSIS...
Dry weather and near normal temperatures will continue through
tonight as synoptic situation remains relatively unchanged.
Unsettled conditions are possible tomorrow and into the weekend
as moisture moves in from the Atlantic. Well above normal
temperatures are expected by Sunday into early next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
KEY MESSAGE:
- Seasonably warm and dry overnight.
Little change in the overall pattern and the surface high
remaining in control of the region. Easterly winds will become
light and variable overnight. Can`t completely rule out some
ground fog south of I-20 towards daybreak, but the threat is
low.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
KEY MESSAGES:
- Tropical wave will pass south of us Friday.
- Increasing chance for afternoon and evening thunderstorms.
Westerly moving tropical wave/low pressure center is forecast
to move ashore northern Florida or southeastern Georgia during
the day on Friday, pushing westward by the evening hours.
Initially, our forecast area will have quite a bit of subsidence
north of this feature as we`ll still be stuck underneath the
mid and upper level ridge. As a result, the day is initially
expected to be dry and warm. By the afternoon hours, however, a
surge of PWs is forecast by all guidance, with HREF members
generally showing the highest PWs >1.5" approaching the I20
corridor and points southward. This is the area most likely to
see rain between 2p and 8p, though it should remain generally
scattered in nature. Thunderstorms are possible but generally
expecting things to remain sub-severe. I do want to note that
the well- performing HRRR has been consistently showing no
precip developing but it also is mixing the boundary layer
substantially more than its fellow CAMs (even those that have
had that bias in the past) so tend to think that is the outlier.
Highs will likely end up in the lower 90s, maybe a touch cooler
in the coastal plain where clouds are likely to develop earlier
in the day. Showers/storms will likely hang around for a bit
after sunset, diminishing as the night goes along. Look for lows
in the upper 60s.
Saturday looks fairly similar, as the plume of higher PWs is
expected to fully overspread the forecast area by this point. Given
hot temperatures and rich boundary layer moisture, we should see
scattered showers/thunderstorms develop across the forecast area
again on Saturday. Again, generally expecting these to remain
sub-severe but can`t rule out a strong storm here or there. Highs are
likely to be in the low to mid 90s, with overnight lows again in the
upper 60s or lower 70s.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
KEY MESSAGES:
- Heat builds into next week with heat indices above 100.
- Typical scattered afternoon/evening thunderstorms are
expected.
Guidance continues to show fairly conflicting signals in terms
of heat in the long term. The ridge that has been parked across
the OH Valley and Mid Atlantic regions is expected to shift
westward and yield troughing as the next work week approaches.
The first signs of this are expected by Sunday as heights will
begin falling across the Carolinas. Heights should continue to
remain at or below 588dm by Monday and Tuesday as the western
CONUS ridge builds and persistent troughing looks like it may
set up. LREF Members support the operational models in showing,
leading to higher confidence than normal in the pattern
evolution through early next week.
However, the sensible weather that results from this in the forecast
is conflicting to say the least. The trough is forecast and expected
to yield a surface low into the northeast CONUS by Monday, pushing a
weakening cold front towards the FA by Monday afternoon and the
overnight hours. PWs will still be near to slightly above normal
both Sunday and Monday, with scattered to potentially numerous
thunderstorms expected both days given the favorable setup. This
conflicts with models also showing high chances at temps in the
upper 90s to around 100F for highs by Monday. This is also shown on
Tuesday despite the cold front likely stalling near the area. Part
of this looks like it could be westerly or northwesterly flow that
develops in the base of this trough advecting warm (20-22C) 850 hPa
temps across the area Sun-Wed of next week. Given the expectation
that daily showers/thunderstorms will be a risk, and lowering 500
hPa heights, it is hard to believe NBM guidance that temps will make
it to near 100F any day next week, let alone multiple days. Have
capped forecast highs around 98F as that makes conceptual sense
given the forecast as it stands right now. However, while we may
not get as hot as some of the guidance suggests, it will feel
above 100 due to the increasing low level humidity.
Lows will likely be in the 70s given surface moisture in place.
Overall, it does look hot but nothing too crazy for June in the
southeast. By the middle of next week, things still look to be
active with a building western CONUS ridge, so expect daily
chances at rain to continue into Wednesday and Thursday.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
VFR conditions expected through the TAF period.
With high pressure generally in control tonight into Friday,
conditions are expected to remain vfr through the period. Late
afternoon cumulus will be dissipating towards sunset once again.
Winds should diminish to less than 5 knots, but should still be
enough mixing near the surface to keep them from going
completely calm for long periods. In addition, the mixing will
also help to inhibit any fog formation late tonight. Friday will
see an increase in low-level moisture as an area of low pressure
off the coast begins tracking closer to the region. This may
only produce more scattered to occasionally broken vfr clouds
through the afternoon. As for rainfall potential Friday, most
guidance keeps the activity much closer to the coast through
much of the day, but can not completely rule out an isolated
shower approaching ogb late in the afternoon as the sea-breeze
moves inland more.
EXTENDED AVIATION OUTLOOK...Brief restrictions possible in
isolated to scattered afternoon and evening thunderstorms Saturday
with increasing chances Sunday through Tuesday.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...None.
GA...None.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
Area Forecast Discussion
National Weather Service Cheyenne WY
551 PM MDT Thu Jun 20 2024
.KEY MESSAGES...
- Severe thunderstorms possible this afternoon with hail, strong
winds, and heavy rainfall. Cannot rule out a tornado with any
longer track supercells that develop. Severe thunderstorm
potential continues Friday.
- Hot temperatures are expected for Sunday through the middle of
next week. Highs exceeding 100F will be possible (40-60%
chance) particularly on Monday.
&&
.MESOSCALE...
Issued at 1153 AM MDT Thu Jun 20 2024
Mesoscale trends continue to be monitored ahead of today`s
severe weather event in southeast Wyoming and western Nebraska.
As of 18z/noon, high-based convective towers were noted along
and just west of the Laramie Range in southeast Wyoming where
dewpoints are generally in the upper-30s and low-40s with
southwesterly surface winds. A dryline boundary was noted on
KCYS radar imagery over the south Laramie range, which per
surface observations likely extends northward along the western
fringes of the Laramie Range and into the Shirley Basin. East
of this boundary and into the high plains, easterly surface
winds are transporting rich surface moisture toward the dryline
boundary in general east-southeasterly flow. With 30-40 knots of
southwesterly flow aloft, bulk shear values AoA 45 knots are in
place over the high plains.
Several important nuances in satellite and surface observations
are evident that may ultimately assist with zeroing in on the
greatest threat zone today. The character of surface cloud cover
in the eastern Wyoming high plains depicts a gradient of
stabilization, also evident in wind/Td fields. In far southeast
Wyoming over CYS, low- level cloud cover has generally mixed out
late in the morning giving way to clear skies and lower
dewpoint values as a relatively shallow moist layer mixes away.
Farther north in central Platte and Goshen counties, surface
cumulus clouds over the North Platte River valley from BFF
through TOR and GUR have remained in place despite surface
mixing and heating. With surface dewpoints remaining in the low
60s and more backed winds to the east compared with locations
farther south, a favorable combination of deeper surface
moisture and better low-level hodograph shape exists here. Even
farther north along the US-20 corridor from Douglas through
Lusk/Chadron, morning convection has draped an outflow boundary
along this corridor with backed northeasterly flow north of
this feature. It is likely that conditions will remain capped
to the north of this boundary today given plentiful lingering
mid- level cloud cover.
With all this being said, the most favorable overlap of surface
moisture, better directional wind shear, and upper-level support
appears to be throughout Platte and Goshen County Wyoming as
well as points farther east through Scottsbluff and Alliance.
Mid-morning CAM guidance has continuously depicted initially
discrete supercell activity here, eventually merging into a
linear storm mode as outflows pool. Hail early in storm mode,
then high winds later in the day appear to be the most likely
threats. The tornado threat will likely be dependent on if any
initial discrete cells can tap into enhanced low-level shear
near/along the lingering outflow boundary in far northern
Platte, Goshen, Sioux and Dawes counties. These features will
continue to be monitored throughout the early afternoon.
&&
.SHORT TERM /THROUGH SATURDAY/...
Issued at 234 PM MDT Thu Jun 20 2024
Surface low analyzed across east central Albany County this
afternoon. Warm front from this low extends eastward to
Wheatland and eventually to Alliance and into central Nebraska.
Cold front extends southwest into southwest Albany County into
northwestern Colorado. Storms are forming along these fronts
this afternoon. North of the front...there still is some capping
seen on RAP mesoanalysis...while south of the front...surface
based CAPE ranges from 2000 J/KG over southern Wyoming to 3500
J/KG over the central Panhandle. Looks like the HRRR simulated
radar is handling convective development the best this
afternoon.
This supercell tracks east into southern Sioux/northern Scotts
Bluff and eastern Box Butte Counties through late afternoon.
Storms line out over the central Panhandle towards 00Z from
Alliance south west to Kimball. Some redevelopment of storms
behind this line across Platte and Goshen Counties through 02Z.
Concern tonight for stratus and fog returning to the northern
Panhandle. Did bring low clouds and fog back into
Dawes...northern Sioux and Niobrara Counties tonight.
Warm front remains over the northeast portion of the CWA for
Friday afternoon. This will be the focus for severe storms
Friday. SPC has a Slight Risk area identified for Friday
afternoon.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 403 AM MDT Thu Jun 20 2024
A hot and largely dry weather pattern will dominate much of the
week ahead. Friday`s shortwave trough will be off to our east
by early Saturday morning, leaving dry air advection over much
of our area in its wake. The shortwave moving east will break
down the potent ridge that has been dominant over the central
and eastern US this week. However, the ridge will then
retrograde westward and expand over the Four Corners states
through the weekend. Models are in good agreement showing the
ridge remaining fairly stationary but amplifying through the
middle of next week. Ensemble mean 500-mb heights over KCYS
climb from around 587-dm at 12z Saturday to a maximum of 592-dm
by Tuesday evening. Temperatures should return above normal on
Saturday as 700-mb temps climb to around +15C over the Wyoming
portion of the forecast area. Widespread 80s to lower 90s will
still probably be the coolest day of the long term forecast
period. By Sunday, 700-mb temperatures edge up to +16 to +18C
and remain there or higher through at least Tuesday, and
possibly beyond. Look for widespread 90s on Sunday, and possibly
a few degrees higher on Monday. Some areas will have a good
chance at surpassing 100F. Current probabilities of 100+F
temperatures on Monday are sitting around 40% for Chadron,
Torrington, and Bridgeport, but over 60% for Scottsbluff.
Forecast confidence decreases somewhat beyond Monday, as the
amplifying ridge may open the door to a few weak shortwaves
sliding over the top. Some of these could have the potential to
bring surface cold fronts through the area. While there is
nearly every ensemble member has extremely hot temperatures on
Sunday and Monday, about 20% of members bring a front through
our northern counties by Tuesday, and this proportion rises for
Wednesday and Thursday. Overall, the forecast still leans quite
hot, but by mid-week there is a little bit more uncertainty.
Other than the heat, the week ahead looks fairly dry too.
Precipitable water values don`t look too bad, hovering around
average for Saturday into early next week. However, the combination
of dry low-levels (due to the dry-line getting pulled eastward) and
warm air aloft will reduce precipitation chances. We should still
see some activity each day, but it will be much less widespread than
Thursday and Friday. With inverted-v soundings showing up in the
forecast in place of decent mid to upper level moisture lingering,
expect each day to put up some scattered radar echos, but the chance
for measurable precipitation on the ground looks fairly low.
Showers may lead to dry microbursts through this hot period. The
majority of ensemble members allow the dryline to pull back to the
west by Tuesday or Wednesday, increasing low level moisture and thus
the chance for more noteworthy precipitation and thunderstorm
activity for the middle of the week.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 547 PM MDT Thu Jun 20 2024
Concerns tonight with the 00Z TAFs will be remaining
thunderstorms in the Nebraska Panhandle...followed by low
stratus. Line of thunderstorms still making its way through the
Panhandle. Still has to clear KSNY and KCDR over the next couple
hours. Low stratus expected to develop over the Panhandle
airports this evening and continue overnight. Followed HRRR
guidance on timing of IFR onset. Another round of storms
expected Friday afternoon.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
MESOSCALE...MAC
SHORT TERM...GCC
LONG TERM...MN
AVIATION...GCC
Area Forecast Discussion
National Weather Service Goodland KS
656 PM MDT Thu Jun 20 2024
.KEY MESSAGES...
- Marginal Risk for severe thunderstorms early this evening from
northwest Kit Carson county to northwest half of Yuma into
corner of Dundy county.
- Continued very windy Friday with 20%-30% chances for afternoon
and evening thunderstorms, some of which could become severe.
- Weekend looks to remain hot with highs in the 90s. Could be a
few severe thunderstorms Sunday afternoon/evening.
- Hottest temperatures of the period Monday/Tuesday. Heat index
values of 100-105 degrees east of Highway 25.
- Not as hot (highs in the 90s) Wednesday/Thursday with better
chances (20%-40%) for thunderstorms moving through the area
from the west during the late afternoon to overnight hours.
&&
.UPDATE...
Issued at 647 PM MDT Thu Jun 20 2024
Watching cluster of storms draped from roughly the Denver
Airport into the the Nebraska panhandle. The storms are cold
pooling to the ENE and may clip NW portions of Yuma county.
Overall not much change to the forecast.
Did bump up winds from 23-02Z Friday evening as the GFS has been
consistently showing an 8mb pressure rise and 40-45 knot winds
in the 850-800mb range, which if this does come to fruition
would not be difficult to mix down with pressure rises of that
magnitude. RAP and NAM however show 3-4mb pressure rises in the
same period and no where near that magnitude of winds in the
same layer. Previous experience does lean more towards the GFS
solution especially when it comes to winds so am leaning
towards that solution at this time, but is plausible that winds
remain in the 30-35 knot range if the RAP and NAM where to
verify.
&&
.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 115 PM MDT Thu Jun 20 2024
Tonight...a small area of moisture in the 700-500mb layer is
forecast to move off the Palmer Divide area and into the northwest
corner of the forecast area (from near Flagler to Wray north) early
this evening, supporting 20%-30% chances for showers and
thunderstorms. The primary hazards will be outflow wind gusts to 60
mph and hail to the size of quarters. Otherwise, it should generally
be clear with low temperatures in the lower 60s to around 70. Breezy
to windy southerly winds will continue generally west of Highway 25.
Friday-Friday night...a monsoonal type pattern sets up with an upper
trough to our west and ridge centered over the southeast states.
Unfortunately, moisture from Mexico is skirted to the south of the
area (oriented from southwest Kansas to northeast Kansas). There is
a bit more moisture in the 700-500mb layer compared to 24 hours ago
that moves into the northwest half of the area from the Raton ridge
area, supporting 20%-30% chances for showers and thunderstorms north
of a line from Kit Carson to Colby and Norton from around noon MDT
to midnight MDT. A few thunderstorms are possible with hail and
strong wind gusts the primary hazards. It will be windy once again
with southerly winds gusting in the 35 to 45 mph range during the
day, steadily decreasing overnight while veering to the southwest to
northwest.
Saturday-Saturday night...500mb flow shifts from southwest flow
aloft to zonal with troughing to our north and an elongated ridge to
our south. Presently, dry weather is forecast. There could be some
isolated flirting with the northwest corner of Yuma and Cheyenne
counties (Colorado) in the 23z-02z timeframe as some mid level
moisture moves off the Cheyenne Ridge and Palmer Divide into those
areas. High temperatures are forecast to be in the upper 80s to
middle 90s with low temperatures in the 60s.
Sunday-Sunday night...broad upper level ridging strengthens over the
area. High temperatures continue to rise with readings in the middle
to upper 90s. Low temperatures are forecast to be in the 60s. It
appears from the GFS/NAM models show a plume of moisture in the 700-
500mb layer moves into parts of the forecast area from south central
Colorado, supporting at least a 20% chances for afternoon
thunderstorms for quite a bit of the area. As a result, I`ve
expanded the areal coverage of possibility from what the NBM loaded.
Any thunderstorm activity quickly dissipates in the early evening
hours. High temperatures are forecast to be in the 95 to 100 degree
range with low temperatures in the 60s.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
Issued at 115 PM MDT Thu Jun 20 2024
Monday...500mb flow becomes northwesterly, in between ridging to our
south and troughing along the US/Canada border. A subtle weather
system per GFS/ECMWF/GEM 700-500mb relative humidity forecasts and
qpf moves through the area from the northwest during the very late
afternoon through evening hours, supporting 20% chances for showers
and thunderstorms at the moment. High temperatures are forecast to
be in the upper 90s to around 104. This may be a few degrees too
high given typical mixing at 850mb. Regardless, it will be hot. Heat
index values of 100-102 degrees are forecast generally east of
Highway 25. Low temperatures are forecast to be in the 60s to lower
70s.
Tuesday...not a whole lot of change in the 500mb pattern with
another chance (20%-30%) for late afternoon and overnight
thunderstorms. High temperatures remain the middle 90s to around 101
degree range. Heat index values of 100-103 degrees are forecast east
of Highway 25. Low temperatures again the 60s to lower 70s.
Wednesday...500mb pattern shifts the upper high to the southwest
part of the country with a trough approaching the west coast/pacific
northwest. Thunderstorm chances increase into the 20%-40% range
during the afternoon and overnight hours as a potentially more
organized weather system moves off the Colorado front range and
through the area. High temperatures are forecast to not be as hot as
prior days with readings in the 90s. Heat index values remain in the
90s. Low temperatures fall into the 60s.
Thursday...current guidance indicates another chance (20%-40%) for
thunderstorms to move through the area during the afternoon and
overnight hours from the west. High temperatures remain in the 90s
with low temperatures in the 60s to lower 70s.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 436 PM MDT Thu Jun 20 2024
VFR conditions are forecasted for this TAF period. Winds will be
the main story as breezy to gusty southerly winds will continue
for the majority of the period; although winds do look to relax
at KMCK overnight as they will be further away from a surface
low across E Colorado. Fairly good signal for LLWS from the SW
around 45-50 knots to affect each terminal tonight as well .
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.
&&
$$
UPDATE...Trigg
SHORT TERM...99
LONG TERM...99
AVIATION...Trigg
Area Forecast Discussion
National Weather Service Gray ME
1033 PM EDT Thu Jun 20 2024
.SYNOPSIS...
Heat ridge breaks down this evening as a surface
cold front pushes through the area bringing cooler weather.
Front stalls just to our south and becomes a focus for rain
shower activity tomorrow and Saturday. Warmer again on Sunday
with thunderstorms and locally heavy rain. Quiet weather is
expected by the beginning of next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
1030 PM Update...Main focus of this update was to trim down PoPs
as the bulk of shower activity has exited the area. Recent runs
of the HRRR also suggest shower activity will be limited
overnight. Have also increased fog coverage with this update as
drier air does not arrive until tomorrow morning.
8 PM Update...Convection is on the downward trend with much of
the activity shifting south of the NH/MA border. Therefore, have
allowed for the Severe Thunderstorms Watch to expire as
scheduled. Have mainly refined PoPs based on latest radar trends
and hi res guidance which keeps chances for showers going
through midnight.
5:50pm Update... A quick update to better match POPs with radar
trends so far and through the rest of the evening. Severe storms
remain possible for a few more hours, but the best chance for
storms looks to be toward southern NH where the air hasn`t been
worked over as much yet.
Previous...
The backbone of the heat breaks this evening as strong to
severe storms move through the region. The heat threat is
steadily evolving into a severe threat for this afternoon with a
cold front slowly pressing southward through the afternoon
hours. Isolated storms are expected to grow and consolidate
into clusters and slow moving lines of storms through the
afternoon and into the evening. With west- southwesterly flow,
storms are not expected to weaken until after they move
offshore, bringing the severe threat right to the coastline.
A severe thunderstorm watch has been issued for the entire
forecast area, with storms already firing early this afternoon.
Yesterday`s storms proved damaging with just high CAPE and cold
pools. Today, a little more shear and better forcing from the
front combine with the hot and humid conditions to bring severe
storms with a higher degree of confidence than we often see.
Damaging winds are likely to be the most widespread impact, but
some hail around quarter size is also likely with a few storms,
especially in the more isolated ones forming during the mid
afternoon hours.
The lines and clusters of storms push offshore through the
evening hours after sunset, with much cooler conditions expected
behind the storms by late evening. The front slowly moves
through during the overnight hours, bringing in drier air
overnight. Before this drier air filters in, patchy fog is
likely by late evening and into the overnight hours, especially
through the valleys and along the coastline.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
The front continues to slowly move through the CWA tomorrow,
with temps warming into the mid 80s through southwest NH ahead
of the front. Behind the front, cool and dry northeasterly flow
keeps temps in the low to mid 70s through much of Maine and the
Seacoast of NH. Showers, and some thunderstorms continue near
and behind the front tomorrow as moisture continues to ride
along the front. This makes for a cool and showery day for much
of southern and western Maine and eastern NH. Further behind the
front, central Maine may escape most of the shower activity to
see more sunshine, with temps warming into the mid to upper 70s
accordingly.
Scattered showers continue through the overnight hours tomorrow
night as the front lingers to our south. Placed of the cooler
side of the ridge, waves of leftover convection and periods of
showers likely continue to move through the region as these
features ride around the ridge. The cooling trend continues,
with lows dipping into the upper 50s to low 60s across most of
the area.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Overview: Relatively progressive flow after the NE CONUS ridge
becomes suppressed with a more active polar jet stream and Canadian
troughs moving across New England. Shortwave ridging is expected
between the troughs bringing a see-saw weather pattern over the next
week. This will bring periods of active weather with thunderstorms
and temperature swings from near normal to above normal.
Impacts: Localized heavy rain is possible Saturday across Western
NH with a higher threat for localized flash flooding on Sunday
across the mountains. In addition, severe weather can`t be ruled
out Sunday at this time across most of the forecast area.
Forecast Details: On Saturday a stationary boundary will be located
in the vicinity of Southern NH with surface ridging to our north.
This will separate the heat and moisture from the Mid-Atlantic and
cooler dry airmass from Canada. Expect showers and isolated
thunderstorms along this boundary with the highest chances for
locally heavy rain across Southwest NH at this time. By Sunday the
stationary boundary becomes a warm front and surges north of the
area bringing the region back into the warm sector. Threat for
severe weather will increase as a robust mid-level shortwave and
associated cold front pushes through the area sometime late Sunday
into Monday morning. There is some model spread on the order of 12
hours or so on timing of FROPA at this time. Monday the shortwave
trough swings through with the potential for much cooler weather and
showers, but this depends on the timing of the trough. Tuesday looks
to have the highest potential for being the driest day of the week
as a shortwave ridge moves over the area with a rebound in the
temperatures. Wednesday could be warm once again as a return to
southwest flow is possible ahead of the next approaching trough. A
period of storms is possible in the Wednesday night into Thursday
timeframe as the next cold front swings through the area.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Short Term...Showers and occasional thunderstorms are expected
at all terminals through the early evening hours. These storms
push offshore by late evening, with brief periods of BR or FG
possible in the valleys overnight. PROBs are too low to go too
strong with the fog threat, but IFR to LIFR can`t be ruled out
late tonight at LEB, HIE, and RKD. Conditions improve tomorrow
morning, but periods of MVFR ceilings are likely through coastal
terminals. Showers and brief restrictions are possible at all
terminals tomorrow afternoon and night, but otherwise mainly VFR
to occasional MVFR conditions are expected.
Long Term...Showers and thunderstorms could bring temporary MVFR to
IFR conditions on Saturday with the highest threat across the
airfields of New Hampshire. Similar impact to operations is possible
on Sunday as the threat for afternoon thunderstorms increases along
with gusty southwest winds. Storm coverage should trend downward by
the beginning of next week.
&&
.MARINE...
Short Term...A cold front slowly moves southward across the
waters overnight tonight and tomorrow. Thunderstorms with strong
wind gusts are likely near the coast late this afternoon and
early evening. Winds shift to northeasterly behind the front
tonight, but conditions are expected to remain below SCA levels
through tomorrow night.
Long Term...Storms are possible over the waters on Saturday. By Sunday
strong SW winds could develop leading to marginal SCA conditions by
the afternoon and evening hours ahead of an approaching cold front.
Cold front pushes through on Monday with a return to offshore flow
and possible SCA conditions.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
NEAR TERM...Clair/Schroeter
SHORT TERM...Clair
LONG TERM...Dumont
AVIATION...Clair/Dumont
MARINE...Clair/Dumont
Area Forecast Discussion
National Weather Service Tucson AZ
136 PM MST Thu Jun 20 2024
.SYNOPSIS...Hot temperatures this afternoon with an Excessive Heat
Warning in effect for portions of southeast Arizona. Increased
moisture will result in the potential for thunderstorms each day
into next week week. Storms this afternoon into evening could
produce strong winds and blowing dust mainly from Nogales to Tucson
and into Pinal County. Windy conditions are also expected into
Friday. The added moisture will also result in temperatures dropping
back down close to seasonable levels through the weekend.
&&
.DISCUSSION...Plenty of active weather to talk about today as a more
monsoonal pattern/moisture regime is developing. East to southeast
winds are ongoing, mainly from points Tucson eastward with a
southerly to southwesterly flow elsewhere. Given the strong surface
pressure gradient, we`ve seen wind gusts between 40 and 50 mph for
portions of Graham and Cochise County where a Wind Advisory remains
in effect until 5 AM Friday. Moisture levels have increased
considerably with PWAT values of 1 to 1.25 inches from Tucson
eastward, but still between 0.5 inch to 1 inch west of Tucson where
the moisture hasn`t made it quiet yet. For this afternoon, we`re
particularly focused on the potential for a north-south line of
showers and thunderstorms developing across Eastern Pima/Eastern
Santa Cruz/Eastern Pinal/Western Graham/Western Cochise Counties.
This north-south line of showers and thunderstorms is forming along
the western edge of the moisture push (pseudo dry line) with the mid
to upper level flow generally pushing the storms that do develop
towards the east to northeast. MLCAPE values this afternoon per the
RAP are around 500-1000 J/KG in this favored zone with DCAPE values
nearly 2000 J/KG. Given this profile, the main concern with any
thunderstorms will be strong/gusty outflow winds producing areas of
blowing dust. With that said, a Blowing Dust Advisory remains in
place between 3 PM and 8 PM this evening. Not a lot of rain with
these storms with dry lightning potential in spots as well.
Convective activity will diminish after sunset this evening, and
then the focus overnight into Friday morning will continue to be the
larger scale east to southeast winds. The normally more susceptible
spots for east to southeast winds (including the south and east
portions of the Tucson Metro) will especially see the winds kick up
tonight into Friday morning. A few locales will see sustained winds
approaching advisory levels (30 mph). We didn`t expand any wind
headlines on this forecast cycle but this is something we`ll
continue to monitor this evening and overnight. HREF probabilities
for wind gusts over 45 mph are over 50 percent in these localized
most favored spots so the winds will certainly be noticeable
overnight into Friday morning for many folks.
For Friday, wind speeds will gradually diminish as the day
progresses with the main focus turning to the deeper moisture and
convective potential. With the increased moisture, temperatures will
drop about 3 to 6 degrees for most locales compared to today. PWAT
values Friday will increase to around 1 to 1.5 inches and these
values range from 150% to 225% of normal so it`s certainly
anomalous to have this much moisture early in the monsoon.
HREF/CAMS are showing isolated to scattered showers and
thunderstorms across most of southeast Arizona Friday afternoon into
evening. Main concerns will continue to be gusty winds with brief
localized downpours with the strongest storms.
For this weekend, additional moisture makes its way into the region
with PWAT values increasing to between 1.25 inches near the NM
border to nearly 2 inches for the western deserts. These values are
2 to 3 standard deviations above normal for this time of year. With
that said, the mid/upper high will be just to our north and east
with warm temperatures aloft that will partially mitigate
convection. However, given the deep moisture, we`ll certainly see
scattered mainly afternoon and evening showers and thunderstorms
this weekend.
The ensembles are showing a slight meander early to mid next week of
the mid/upper level high to the south and west as it strengthens
slightly. This type of regime would result in thunderstorm chances
shifting to locales generally from Tucson south and eastward. With
the high increasing in strength, temperatures bump back up during
this timeframe to about 3 to 5 degrees above normal.
&&
.AVIATION...Valid through 22/00Z.
SCT-BKN clouds 10-14k ft AGL KTUS/KOLS eastward. Convergence along a
surface boundary will likely lead to isolated to scattered -SHRA/-
TSRA starting around 21/21Z through about 22/03Z. Main terminals
affected will be KTUS and KOLS. Storms will be capable of winds 35-
45 kts with a 10-30 percent chance for winds in excess of 50 kts.
Outside of storms SFC winds become SELY at 15-25 kts with gusts to
30-40 kts across much of the forecast area. The strongest winds are
expected at KDUG and KSAD terminals. Aviation discussion not updated
for TAF amendments.
&&
.FIRE WEATHER...Temperatures are expected to peak today from
Tucson westward, then more seasonable temperatures thereafter.
Surface winds currently east to southeast from Tucson eastward and
west to southwest areas west of Tucson. The strongest winds will be
in the Upper Gila River Valley near Safford as well as near Douglas
along the International and NM borders. The increased moisture with
min RH values in these locales currently 20-30 percent. So while the
winds are at critical levels, RH values will remain just above
critical levels but certainly still elevated fire weather conditions
due to the strong winds and dry fuels Thursday. Breezy to windy
conditions continue Friday, though increased moisture will have
overspread more of the forecast area. A mixture of dry/wet isolated
to scattered storms are expected this afternoon from Tucson eastward
and then to include the remainder of southeast Arizona Friday. As
moisture remains this weekend, isolated to scattered thunderstorms
will continue each day through the weekend into early next week with
a low to mid grade monsoon pattern in place.
&&
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning through 8 PM MST this evening for AZZ501>506.
Blowing Dust Advisory from 3 PM this afternoon to 8 PM MST this
evening for AZZ502-504>506.
Wind Advisory through 5 AM MST Friday for AZZ508-509.
&&
$$
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson