Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/14/21
Area Forecast Discussion
National Weather Service La Crosse WI
1030 PM CDT Sun Jun 13 2021
.SHORT TERM...(This evening through Monday)
Issued at 127 PM CDT Sun Jun 13 2021
Isolated storms remain possible across north-central/central WI
late today, although observational trends favor lower severe/
convective potential.
GOES water vapor channels early this afternoon show a shortwave
trough within NW flow dropping across the northern Great Lakes.
The question continues to be whether any convection will impact
north central/central WI through early evening with the
shortwave/cold front. Long, straight hodographs would favor
supercellular convection (as suggested by some longer-lived model
updraft helicity tracks via the 12Z HREF), but weak low-level
moisture/mid-level lapse rates will significantly limit instability.
12Z GRB/MPX soundings showed very shallow low-level moisture.
Moisture transport is generally on the weak side ahead of the wave
and will be countered by diurnal mixing. RAP indicates only a narrow
axis of up to a few hundred J/kg of MLCAPE at Medford, WI with dew
points in the 40s/low 50s. Other CAMs show a range in convective
coverage, modulated by instability/moisture, but current dew points
in the 40s/low 50s suggest moisture will be on the meager side
(closer to the RAP/HRRR), limiting the convective/severe potential
when combined with weak forcing. Given the shortwave trajectory,
expect the higher precip chances to remain north/east of the area,
but will have to monitor north-central WI for any isolated storm
development late this afternoon with wind/hail potential. This risk
remains highly conditional, and trends favor most parts of the area
remaining dry.
High pressure will build across the area into Monday with cold
advection in the wake of the short wave/front ushering in slightly
cooler, dry air. Highs will mostly be in the 80s on Monday with
plenty of sunshine.
.LONG TERM...(Monday night through Sunday)
Issued at 127 PM CDT Sun Jun 13 2021
Upper ridge over the western US will dominate the weather through
mid week. Highly amplified northwest flow over the upper midwest
will keep temperatures and humidity on the pleasant side for mid
June.
For those that are hoping for some rainfall, the next time period to
watch is Thursday and Thursday night. Model consensus is for the
upper ridge to flatten as an upper low pushes into it across
northern Canada. In this scenario, convergence along the attendant
cold front could have the potential to support convection. However,
there are many factors working against precipitation including
limited moisture with the system and the northern track of the upper
low. If the upper ridge does not flatten as quickly as the models
suggest, the low would likely track farther to the north and our
precipitation chances would decrease accordingly. This is reflected
in the ensemble model runs which have a significant spread in
solutions approaching Thursday, further reducing confidence.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1030 PM CDT Sun Jun 13 2021
Cigs: generally SKC/SCT VFR conditions expected through Tue.
WX/vsby: no impacts expected.
Winds: north northwest overnight with cold front sinking south of
the TAF sites. KLSE more south/southeast due to decoupling...but
swinging northwest by 15z or so.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...JM
LONG TERM...DMD
AVIATION...Rieck
Area Forecast Discussion
National Weather Service Binghamton NY
919 PM EDT Sun Jun 13 2021
.SYNOPSIS...
Scattered showers and thunderstorms are expected through
tonight. A few storms may produce damaging winds and heavy rain,
with localized flooding possible. Scattered showers and
thunderstorms continue Monday, as another disturbance drops
through the region. Though a small chance of showers lingers
Tuesday, drier and cooler weather is anticipated for midweek.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
910 PM Update...
Made rather significant changes to the forecast for this evening
to reflect latest radar trends. Convection has fired up along
the Central Southern Tier of NY to the southern Finger Lakes
along a corridor of enhanced CAPE and closer to the upper level
trough. A few Severe Thunderstorm Warnings have already been
issued for this part of the CWA. Meanwhile, farther south,
across our Northeast PA counties, conditions have been mainly
dry with just a few light showers around. Therefore adjusted
PoPs to upgrade the Central Southern Tier of NY and Finger Lakes
regions to likely and adjust PoPs downward farther south. Now
that it is post-sunset, instability will likely be on the
downward trend as the rest of this evening progresses and
therefore the severe thunderstorm threat will likely decrease
over the next few hours.
Will let the Severe Thunderstorm Watch for the Northern Tier of
PA/Wyoming Valley ride until its scheduled expiration at
02Z/10PM EDT.
640 PM Update...
So far, the strongest storms in PA have stayed west of our CWA
(more across Central PA), closer to the upper level trough and
greater shear. Despite instability present across the Northern
Tier of PA and the Wyoming Valley, the lack of enough lift has
prevented much thunderstorm development up to this point. Still
expecting coverage of scattered showers and thunderstorms to
increase throughout this evening as the trough approaches, but
the overall extent of the severe weather potential for the
above mentioned areas (where a Severe Thunderstorm Watch remains
in effect until 10PM) is somewhat questionable. The greatest
coverage of showers and storms may not be until after sunset and
by then, diurnally-driven instability will be waning. That being
said, we are not making any changes to the Watch at this point
and this will be re-evaluated with the next forecast update. Any
storms that do develop with have the potential to bring locally
heavy rainfall.
In terms of tweaks to the official forecast, mainly made
adjustments to PoPs to better reflect current radar trends.
Otherwise, the previous discussion below remains valid.
320 PM Update...
Latest RAP13 analysis shows a band of low level convergence
focused over the Northern Tier of PA, though this is not
readily apparent in surface obs. Instability axis extends across
pretty much the same area, but continues eastward into the
Catskills and Poconos, where cloud cover has eroded over the
past couple of hours. Further north, rather dry air in the low
levels is limiting instability despite slightly cooler air in
the mid-levels -- note lower 50s dewpoints and even 47 at ITH
which would be questionable if not for the 50 at Cortland.
Meanwhile, and upper level trough is moving across SW Ontario,
evident in satellite imagery, while a surface trough/weak cold
front tries to take shape from far western NY into eastern Ohio,
masked somewhat by the lake breeze downwind of Lake Erie.
Expect isolated showers and thunderstorms to increase in
coverage across the Northern Tier of PA, with a general eastward
progression, with stronger cells perhaps curving more to the
southeast as they tap into the mid-level flow. Additional
thunderstorms are expected to develop along the surface trough
early this evening, and will spread east into our area,
including the Southern Tier and parts of the Finger Lakes where
destabilization can occur. Expect several clusters of storms to
be on-going by nightfall, with some heavy rain potential as
storms may try to train along old leftover boundaries. The
greatest risk of heavy rainfall will be over NE PA, where low-
level theta-e ridging looks to lay across, nosing into the
Catskills/Poconos overnight.
Mid-level dry air will promote strong thunderstorm wind gusts
early on, with isolated hail possible given steeper lapse rates, but
as soundings become more modified/moist, heavy rain will become
the primary threat.
For Monday, the main upper trough will swing into southwestern
Ontario, with several bands of rain and embedded thunder
possible. Additional strong to severe thunderstorms can`t be
ruled out again, but will be highly dependent on how convection
evolves overnight into the morning hours. At this time, it
appears areas east of I-81 will be most likely to recover and
destabilize before the main trough swings through.
1145 AM Update...
Low clouds are rapidly breaking up and are currently limited to
the Catskills and NE PA, with plenty of sunshine filling in to
the north and west. With strong surface heating, we could see
temperatures in parts of the Mohawk Valley climb well into the
middle or even upper 80s by this afternoon.
Thunderstorm potential remains a challenging forecast. HRRR and
other high-res models suggest weak low level convergence will
develop along a line roughly from ELM-SYR with southwest flow to
the west of the boundary, and backed S to SSE flow to its east,
apparently influenced by differential heating on either side of
the dissipating cloud layer. Meanwhile, RAP13, NAM, other models
suggest moderate instability will develop across the Twin Tiers
by this afternoon, with SBCAPE vales of 1000-1500 J/KG, and
minimal CIN. Despite the collocation of the low level
convergence and instability, many of these same models struggle
to initiate convection without a larger-scale trigger. That
trigger, a shortwave trough currently over Lake Huron, doesn`t
look to arrive into western NY/PA until around 00Z, assuming it
is being properly initialized.
For now, kept at least a "Chance" PoP in the SW part of the CWA
and extending E-NE along the low level convergence zone early
this afternoon, but the better chances for thunderstorms may not
come until later this afternoon into this evening, with a focus
mainly south of the Southern Tier.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
300 PM Update...
Some patchy fog could hang around Tuesday morning, but should lift
soon after sunrise. A couple of weak shortwaves and low level
moisture will provide some support for a few spotty showers on
Tuesday. With a few hundred J/kg of CAPE present, afternoon
thunderstorms are also possible. Not much is expected for
accumulations, up to a couple of tenths at best. Highs will only be
in the upper 60s to mid 70s as northerly flow advects cooler air
into the area. Showers and skies clear out Tuesday night as high
pressure moves in. Overnight lows will fall into the 40s and 50s
Sunny skies are in store for Wednesday. However, with northerly flow
still present, highs will once again be in the upper 60s to mid 70s.
This cooler air will provide plenty of natural AC as lows drop into
the 40s Wednesday night.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
300 PM Update...
The start of the long term period will start out quiet. High temps
on Thursday will be in the 70s and the lows will fall into the upper
40s and low 50s. Friday will also be fairly quiet, but the pattern
begins to shift. A ridge moves through and flow becomes more
southwesterly, bringing warmer air and moisture to the area. Highs
will be closer to 80 on Friday. Chances for precipitation increase
Friday evening as a cold front approaches the area. This cold front
will bring rain showers and possibly some thunderstorms through
Saturday night. Models still differ on the timing of this system
with GFS still being the faster solution, so followed National Blend
of Guidance (NBM) for the timing which is a little slower like the
ECMWF. Sunday looks to be cooler to finish out the weekend with
also a slight chance for showers with the passing of a weak
system.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
Scattered showers and thunderstorms are expected tonight,
especially this evening across the Twin Tiers. Right now,
confidence in thunder was only high enough to include in the TAF
at KBGM and KELM in two hour TEMPO groups this evening.
Elsewhere, an isolated thunderstorm cannot be ruled out, but
confidence is not high enough to include in the TAF just yet.
Will continue to monitor this potential for potential amendments
if necessary.
In terms of restrictions, mainly VFR conditions early this
evening will likely give way to at least Fuel Alternate ceiling
restrictions overnight at all TAF sites with the exception of
KSYR. Best chance for IFR conditions will be at KAVP, KBGM, and
KELM. Patchy fog/mist is also possible. Conditions are expected
to return to VFR by Monday afternoon, with KAVP likely being the
last terminal to do so.
Another round of scattered showers and thunderstorms is expected
Monday afternoon, although confidence in thunder is too low at
this time to include in the TAFs. This will be fine-tuned in the
upcoming TAF issuances.
Outlook...
Monday night...Some restrictions possible with lower ceilings
and/or patchy fog.
Tuesday...Chance of additional showers and thunderstorms/brief
restrictions, otherwise mainly VFR.
Tuesday night through Friday...Mainly VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...BJG/MPH
NEAR TERM...BJG/MPH
SHORT TERM...BTL
LONG TERM...BTL
AVIATION...BJG
Area Forecast Discussion
National Weather Service Corpus Christi TX
616 PM CDT Sun Jun 13 2021
.AVIATION...
VFR conditions will prevail through most of tonight. Light patchy
fog and low CIGs are expected to briefly develop toward early
Monday morning, leading to MVFR/IFR conditions, especially from
ALI to VCT. VFR conditions will quickly resume mid morning Monday
and will continue through Monday afternoon. There is a chance of
showers and thunderstorms across the VCT area Monday afternoon.
Winds will generally be light and variable a majority of the TAF
period.
&&
.PREV DISCUSSION... /Issued 245 PM CDT Sun Jun 13 2021/
SHORT TERM (Tonight through Monday Night)...
Heat index values this afternoon are climbing into the 103 to 106
range and are expected to hold in this range for the next few
hours before cooling with sunset. Surface winds are remarkably
light and generally less than 5 MPH across the Coastal Bend and
Victoria Crossroads. While these elevated heat index values are
just a bit lower than the criteria normally used to issue a
Special Weather Statement, have concerns that very light winds
will only increase the heat stress that individuals experience
while outdoors and have opted to issue a short statement for heat
for this afternoon.
Water vapor imagery this afternoon showed a small disturbance
embedded in the northeast flow aloft translating down the Middle
Texas coast. Despite the presence of this feature, any convection
this afternoon appears to be limited by drier air over the region
as visible satellite shows a rather compressed cumulus field. Some
enhancement has been noted near and east of Matagorda Bay, where
the sea breeze has begun to move inland. A remnant mesoscale
convective vortex (MCV) was noted earlier in the day moving across
Brazoria and Matagorda counties in the vicinity of this sea
breeze, but has become less defined during the afternoon hours and
is difficult to determine whether or not the feature still exists
on satellite and surface observations.
Regardless, deeper convection that it able to form along the sea
breeze north of the region... aided by whatever forcing from the
disturbance aloft and additional surface convergence the remnant
MCV provides... may be able to propagate into the Victoria
Crossroads before sunset. Have maintained low (20 percent) rain
chances as a result of this potential, with the thinking for the
remainder short term forecast also remaining virtually unchanged.
Dry conditions will persist across the region tonight with
clearing skies allowing for another round of radiation fog to
develop across the Coastal Bend and Victoria Crossroads after
midnight tonight. Ample near surface moisture may result in dense
fog to develop, but it is interesting to note that recent HRRR
runs have backed off on lower visibilities overnight. This is
probably due to anticipated subsidence over the region as the
disturbance aloft drops farther southwest, but with forecast
soundings showing the boundary layer decoupling after midnight
(limiting the potential for influence from this feature) will
continue to maintain fog in the forecast. Otherwise, expect lows
to bottom out in the low to mid 70s.
Morning RAOBs depicted a broad upper ridge centered over New
Mexico with a shortwave trough rotating around the eastern
periphery of the ridge across the Red River. While the trough over
Oklahoma will remain too far north and west of the region to
affect sensible weather in the short term, it is expected to nudge
weak surface troughs or convergence zones towards the region by
Monday morning. Returning moisture and the presence of these
boundaries will result in a new focus of shower and thunderstorm
activity on Monday, some of which may advect towards the region
from South Central or Southeast Texas as northeast flow aloft
persists. This deeper moisture will also allow for slightly higher
heat index values by Monday afternoon. Highs in the upper 80s to
mid 90s along the coast will increase to the low 100s along the
Rio Grande, allowing for most of the region to feel like it is in
the 100 to 110 degree range.
As the upper ridge wobble over the Four Corners region on Monday
night, additional disturbances will translate across the region as
flow aloft becomes more easterly. This may allow for shower and
thunderstorm development to continue across the Victoria
Crossroads into the early morning hours Tuesday with lows across
the region in the mid to upper 70s.
LONG TERM (Tuesday through Sunday)...
Not much change to the long term forecast. A strong mid-level ridge
will remain nearly stationary over the Four Corners region through
Friday with a slight westward drift thereafter. This will keep
conditions primarily dry with partly cloudy skies as a northeasterly
flow persists over the area. A few sea breeze showers and
thunderstorms will be possible throughout the week as a couple of
weak shortwave troughs push through South Texas around the
periphery of the upper ridge, and PWATs hover near 2 inches along
the coast.
Temperatures will be hot through mid week with heat indices ranging
from 105-109 Through Wednesday then 100-105 through the rest of the
week. Highs will be in the 90s for most of the area with triple
digits along the Rio Grande. Lows will be in the 70s. Cannot rule
out some patchy fog across the inland coastal plains during the
early morning hours this week.
The National Hurricane Center continues to monitor an area of low
pressure over the Bay of Campeche for potential tropical
development. At this time there is a 20% chance of development in
the next 48 hours and a 50% chance of development in the next five
days. The deterministic and ensemble models show a considerable
spread and thus there remains uncertainty with regards to the
structure, future path, and potential strength of this system.
Residents along the Mid Texas coast should continue monitor the
latest forecasts from the NHC and ensure your preparedness plans
are in place. Its possible we will see increasing tides, swells
and rain chances by the end of the week into next weekend.
Fortunately we will be moving into an astronomical tide minimum by
next weekend which should help reduce any potential coastal flood
impacts.
MARINE...
Isolated showers and thunderstorms will be possible along the
coast north and northeast of Port Aransas on Monday with the
onshore flow remaining weak. A weak onshore flow will persist
through Thursday night. Winds are then expected to increase to
moderate out of the northeast on Friday in response to a low
pressure system moving northward into the western Gulf. The
National Hurricane Center indicates this system has a 50 percent
chance of becoming a tropical depression in the next 5 days. Small
Craft Advisory conditions may begin over the offshore waters
Friday night due to increasing swells. Isolated showers and
thunderstorms will be possible Tuesday through Friday, becoming
scattered Friday Night through Saturday Night. Mariners should
monitor the latest information from the National Hurricane Center.
&&
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 74 94 75 93 76 / 0 0 10 10 0
Victoria 75 96 75 94 74 / 10 30 20 30 10
Laredo 76 102 77 100 77 / 0 0 0 10 0
Alice 72 98 72 95 73 / 0 0 10 10 0
Rockport 76 93 77 92 77 / 0 10 10 10 0
Cotulla 77 101 77 100 77 / 0 0 10 10 0
Kingsville 72 96 74 93 74 / 0 0 10 10 0
Navy Corpus 77 90 78 90 79 / 0 0 10 10 0
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
TE/81...AVIATION
Area Forecast Discussion
National Weather Service Cheyenne WY
529 PM MDT Sun Jun 13 2021
.UPDATE...
Issued at 314 PM MDT Sun Jun 13 2021
Severe Thunderstorm Watch 268 has been issued for southeast
Wyoming and Nebraska Panhandle through 04Z tonight. Updates have
been sent.
&&
.SHORT TERM...(This evening through Monday)
Issued at 240 PM MDT Sun Jun 13 2021
Forecast challenges deal with severe thunderstorms today.
Currently...thunderstorms developing along the Laramie Range this
afternoon. Surface trough lays from near Cheyenne to Torrington
with moist southeasterly upslope flow in the lower layers. Cold
front being analyzed across central South Dakota back into
northeastern Wyoming. SPC Mesoanalysis showing EMC RAP surface
based CAPE around 5000 J/KG out in the Panhandle and around 2500
J/KG where the storms are forming on the Laramie Range. Still
some small capping across southeast Wyoming with around 50 J/KG
convective inhibition. Main limiting factor right now is lack of
shear.
Later this afternoon...northern front drops south into the
northern Panhandle and Converse County in east central Wyoming.
Sfc to 6km shear increases to 35kts across the northern Panhandle
to around 50kts down here near Cheyenne. HRRR and NAMNEST short
term guidance forecasting showers blossoming along the front as it
slowly drops south southwestward into the southern Panhandle and
southeast Wyoming plains. Could be a long show tonight as both
models continue showers and storms through 09Z.
SPC showing a Day 2 Marginal Risk area for the Nebraska Panhandle
for Monday afternoon. Latest guidance showing no PoPs over that
area for Monday. But with dewpoints in the 60s...surface boundary
in the Panhandle and a weak upper southwest dropping
shortwave...decided to add low chance PoPs for the Panhandle. and
.LONG TERM...(Monday night through Saturday)
Issued at 323 AM MDT Sun Jun 13 2021
Monday, the moisture sticks around the Nebraska panhandle with
PWATs around 1.00 in through the afternoon. Daytime heating will
still be strong with the upper-level ridge holding strong over
northwest Wyoming, so the panhandle is still conducive to
thunderstorms, but confidence is lower for Monday`s convection.
Tuesday, the ridge begins to erode, turning our winds back to
westerly/southwesterly, advecting warmer, drier air into southeast
Wyoming and western Nebraska. Afternoon highs for Tuesday and
Wednesday are in the 90s to 100 degrees for some areas with
humidities dropping to the teens and lower 20s. Winds should
remain between 5 and 15 knots, but with the temperatures being so
high and the air being so dry, there is still elevated fire
weather conditions.
Finally Thursday we begin to see a downward trend in temperatures
as winds turn northwesterly. Afternoon highs are still expected to
be in the 80s to lower 90s through the weekend though, with
overnight lows in the 50s and 60s. Next chance of precipitation
after Monday will be Friday afternoon.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 525 PM MDT Sun Jun 13 2021
Wyoming TAFS...VFR. Thunderstorms in the vicinity at Cheyenne
until 03Z. Wind gusts to 30 knots at Laramie and Cheyenne until
03Z, then to 23 knots at all terminals after 15Z Monday.
Nebraska TAFS...VFR, except for occasional MVFR and wind gusts to
45 knots in thunderstorms until 02Z at Scottsbluff. Thunderstorms
in the vicinity at all terminals until 05Z. Wind gusts to 26 knots
until 05Z, then to 24 knots after 15Z Monday.
&&
.FIRE WEATHER...
Issued at 240 PM MDT Sun Jun 13 2021
High pressure over the Rockies will keep temperatures above normal
and very dry humidity over the next several days. Increasingly
warmer temperatures and single digit afternoon humidities from the
Laramie Range west. Until fuels are turned over to YES on rapid
fire spread...fire weather conditions will remain below critical
levels. A windy day expected Wednesday into Thursday across Carbon
and Albany Counties....with afternoon humidity in the single
digits.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
UPDATE...GCC
SHORT TERM...GCC
LONG TERM...LK
AVIATION...RUBIN
FIRE WEATHER...GCC
Area Forecast Discussion
National Weather Service Duluth MN
819 PM CDT Sun Jun 13 2021
.DISCUSSION...(This evening through Saturday)
Issued at 431 PM CDT Sun Jun 13 2021
Summary: Showers and thunderstorm chances continue this evening
for the Arrowhead, northwest Wisconsin, and the I-35 Corridor.
Temps trend cooler Monday and Tuesday, but remain a few degrees
above normal. Warmer temperatures return for Wednesday and
Thursday along with a few more chances of rain and thunderstorms.
Temperatures for Friday through next weekend are expected to be
either side of normal, a welcome break from the recent heat with
highs in the upper 60s to upper 70s.
Showers and thunderstorms remain in the picture this evening for
the Arrowhead, northwest Wisconsin, and the I-35 corridor. Surface
low pressure was centered near Brainerd late this afternoon with
a convective mesohigh over the Arrowhead. These features will both
move eastward with time tonight. As the low approaches northwest
Wisconsin, low-level convergence will increase along the
combination lake breeze and outflow boundary from this mornings
storms. Forecast and observed cloud bases in the warm sector are
around 8-10 kft, so we need to provide a considerable amount of
lift before we can realize the meager MLCAPE available. SPC
mesoanalysis, RAP, and HRRR forecasts suggest any storms which
develop will have 300-800 J/kg to work with. There is considerable
dry air in the mid-levels over the warm sector which will cause
dry air entrainment and further suppress convection initially.
Should storms develop, additional convection along resultant
outflow boundaries should sustain storms through early evening.
Deep layer 0-6 km shear on the order of 70 kts and effective shear
of 40 to 60 knots in addition to 500 mb flow of 55 to 60 knots
should provide a fast storm motion toward the southeast. Long,
nearly straight hodographs suggest damaging winds and large hail
will be the primary risk with storms initially. Should a storm
form on the lake breeze over Carlton, Pine, or southern Douglas
counties, the storm motion and orientation of the boundary may
support a brief tornado risk. However, high cloud bases and meager
instability discount this potential. It seems the tornado risk is
non-zero, but probably less than 1 percent.
Over the Arrowhead widespread convection will continue into this
evening associated with the mid-level forcing closer to the upper-
low and shortwave trough. A few wind gusts of 45 to 55 mph are
not out of the question with that convection, but the hail threat
is near-zero.
Another shortwave trough farther upstream into northwest Ontario
may bring a few showers and storms back to the International
Border area and the Arrowhead tonight. Storms will weaken with
time with the loss of daytime heating tonight.
Mid and upper-level ridging over the Northern Plains and the
Rockies will keep Minnesota and Wisconsin in northwest flow aloft.
Another shortwave trough will dive southward out of Ontario
Monday and may bring a few sprinkles or light rain showers to the
Arrowhead and northwest Wisconsin. Temperatures Monday and Tuesday
will trend a little cooler, but still several degrees above
normal.
Warmer temperatures and rain chances return to the forecast
Wednesday and Thursday. A closed low is expected to move over the
northern Prairies and into northwest Ontario Friday and Saturday
with a lobe of much cooler 850 mb air. Temperatures will trend
cooler Friday through next weekend and will be either side of
normal. With the cold air aloft, there will be chances of showers
and thunderstorms each day. Timing differences and the track of
the upper low preclude a mention of precip in the forecast until
Sunday afternoon.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 643 PM CDT Sun Jun 13 2021
Surface low pressure was in west central Wisconsin this evening
and will move southeast tonight. A few thunderstorms were
occurring over northwest to north-central Wisconsin. Northwest
flow aloft was sending a shortwave southeast and it along with a
surface trough were producing showers and storms near the
International Border. The storms will last another 2 to maybe 4
hours before they dissipate. A strong storm is possible both in
northern Wisconsin which has much stronger deep layer shear but
but is weaker on instability and in far northeast Minnesota which
will have a bit higher instability but lower shear. For the TAFs,
we expect them to remain dry through the period along with VFR
conditions. There will be a cumulus field that develops over parts
of the Northland Monday, mostly widespread in far northeast
Minnesota. A few showers could develop as well there. Gusty winds
this evening will diminish tonight then ramp up again on Monday as
deep mixing is expected.
&&
.MARINE...
Issued at 820 PM CDT Sun Jun 13 2021
The strong northeast winds have quickly diminished this evening.
Winds will gradually become westerly overnight, from 5 to 15 knots
with a few gusts to 20 knots. There may still be an isolated
thunderstorm this evening, most likely between Grand Portage and
Silver Bay. The main threat will be lightning. Winds will start
out west to northwest on Monday then veer north to northeast by
early evening. Speeds will be at or less than 15 knots except for
a few higher gusts. North to northeast winds will continue Monday
night less than 15 knots. T
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 54 79 51 74 / 10 0 0 0
INL 51 77 47 79 / 10 0 0 0
BRD 55 84 52 81 / 0 0 0 0
HYR 51 81 50 77 / 40 10 10 0
ASX 52 78 48 71 / 30 10 10 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
DISCUSSION...Huyck
AVIATION...Melde
MARINE...Melde
Area Forecast Discussion
National Weather Service Grand Rapids MI
946 PM EDT Sun Jun 13 2021
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 318 PM EDT Sun Jun 13 2021
- Chance of rain tonight then cooler and less humid through
Thursday
- Chance of showers/thunderstorms late week
&&
.UPDATE...
Issued at 946 PM EDT Sun Jun 13 2021
I have increased the chance for rain over most of the CWA tonight
as a result of recent radar loop, IR image loops and some common
sense meteorology. The short story is we have a rather strong and
quickly digging upper level system. The axis of the polar jet core
(we get into the left exit region of the jet) drops nearly due
south overnight. In response to that the low level jet really
strengthens overnight. By 5 am we have 35 to 40 knots on the low
level jet amid at Holland Michigan. There is strong speed
convergence west of US-131. Given this under the jet core exit
region I have to believe there will be a lot of dynamic lift going
on. The current radar images show a bowing band of thunderstorms
from the Door Peninsula to near Traverse City. The HRRR does not
have any forecast echos that far south at this time. However the
12z HREF did. There is strong deep layer shear, the 6km shear is
forecasting between 50 and 70 knots of shear at 5 am over this
same area. The down side is the cape is feeble. Still with all
those dynamics I think we can still see some convection (through
fast moving) come farther south than previously through.
Over our north central CWA I have near conditional pops tonight
(hard to believe it would not rain there). Between I-96 and Route
20 I have likely pop and high chance. There is some dry air below
the cloud base, so gusty winds are possible as these storms move
through.
&&
.DISCUSSION...(This evening through next Sunday)
Issued at 318 PM EDT Sun Jun 13 2021
- Chance of rain tonight then cooler and less humid through
Thursday
Shortwave trough coming over the western ridge will serve to
amplify the flow across the CONUS with height falls across the
Great Lakes and the welcome return of cooler and drier air
through much of this week. Dew points drop through the 50s on
Monday and all the way down to the 30s by Wednesday, when morning
lows could also tumble into 30s in the cold spots like Leota, with
lows in the 40s elsewhere.
- Chance of showers/thunderstorms late week
Another shortwave trough tops the western ridge and pushes a sfc
cold front through on Thursday night into Friday bringing the
chance of showers and thunderstorms. Although it is early to pin
down the specifics, there are signals that strong to severe storms
may be possible despite the late night/early morning timing.
Strong warm advection and moisture advection/pooling ahead of the
front along with shear profiles progged to be 35 to 40 knots means
there is potential for a progressive derecho tracking near or just
south of Lower Michigan.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 723 PM EDT Sun Jun 13 2021
A weak area of low pressure will drop southeast across the state
tonight and produce a few showers after midnight...perhaps an
isolated thunderstorm. Moisture is lacking in this system and so
we don`t anticipate anything other than VFR conditions through the
period.
&&
.MARINE...
Issued at 318 PM EDT Sun Jun 13 2021
Low chance of thunderstorms tonight north of Grand Haven then
northerly winds around 10 to 20 knots the next few days with
waves expected to remain less than 4 feet.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...WDM
SYNOPSIS...Ostuno
DISCUSSION...Ostuno
AVIATION...04
MARINE...Ostuno
Area Forecast Discussion
National Weather Service Jacksonville FL
846 PM EDT Sun Jun 13 2021
.UPDATE...
Evening convection weakening over the area as airmass stabilizes
after earlier strong storms that produced isolated hail and
flooding. Upper trough axis over the area and backdoor front
moving sw into se Ga will keep scattered showers and isolated
thunderstorms going until at least midnight. Upper trough will
continue to drift se over ne Fl on Monday with scattered afternoon
storms expected more likely over ne Fl and coastal se Ga where
higher instability and moisture will exist.
&&
.PREV DISCUSSION [720 PM EDT]...
.Short Term.../through Tuesday/...
Stalled frontal boundary will persist across area this afternoon,
and will be a focus for diurnally driven convection. In addition the
sea breezes will also provide sources for convergence. Expect
greatest coverage of convective activity across NE FL due to
location of frontal boundary. Due to the expected slow movement
of convection, periods of heavy rainfall anticipated, especially
across NE FL.
The boundary will dissipate overnight, with convection diminishing
around midnight. Lower chances for convection expected for Monday,
with this activity largely driven by diurnal instability, and
east coast sea breeze interactions.
Another cold front will move into southeastern US Tuesday providing
a prevailing flow from the southwest. This will keep the east coast
sea breeze from pushing inland. Convection will be limited in
coverage again Tuesday, with mainly diurnally driven activity.
Overnight lows will be near normal this period. Highs will trend
below normal on Monday, then near normal on Tuesday.
.Long Term.../Tuesday night through Sunday/...
Cold frontal boundary will sink south across forecast area Tuesday
night, becoming stalled near the GA/FL line Wednesday, where it will
linger through Wednesday night. The front will dissipate during the
day Thursday. Better moisture will be south of the boundary, so
best convective focus over NE FL through Thursday.
High pressure will be to the east, with troughing to the north late
in the week through the weekend, with isolated to scattered
convection expected.
.AVIATION...[Through 00Z Tuesday]
Convection weakening this evening across NE Fl/SE Ga and will
likely linger till around midnight as the well performing HRRR
model indicates. Instability has weakened so expect mostly showers
with isolated thunder possible. VFR conditions will prevail
overnight with chance of MVFR conditions in shower activity. Have
VCTS after 17z Monday as scattered afternoon storms develop.
.Marine...
A frontal boundary will remain stalled over region this afternoon,
and dissipate overnight. Another cold front will move into
southeastern US Tuesday, then stall across area Tuesday night
through Wednesday night, before dissipating Thursday. The region
will be between high pressure to the east and a trough of low
pressure to the north late in the week through the weekend.
Rip Currents: SE GA: Low through Monday
NE FL: Low through Monday
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 70 89 72 94 71 / 20 20 10 30 10
SSI 73 81 75 90 76 / 40 30 20 30 10
JAX 71 85 72 92 72 / 50 40 20 40 20
SGJ 71 83 72 89 74 / 50 50 20 40 20
GNV 71 88 71 88 72 / 50 50 40 50 30
OCF 71 88 72 87 74 / 40 50 40 40 30
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
Area Forecast Discussion
National Weather Service North Platte NE
640 PM CDT Sun Jun 13 2021
.SHORT TERM...(This evening through Monday night)
Issued at 323 PM CDT Sun Jun 13 2021
A weak frontal boundary across SD should settle into the White River
basin this afternoon and this evening acting as a focus for storm
development across wrn and ncntl Nebraska tonight. The ongoing
convection across cntl SD should help push the front south, perhaps
to near the SD/Neb border. Satellite also suggests a very weak upper
level disturbance across ncntl Colo/wrn WY which is expected to set
off storm activity on the Laramie Range and perhaps the Pine Ridge.
Winds aloft are weak at 20 to 25 kts but the bulk effective shear
should increase to 30 to 35 kts given the low level inflow across
the Panhandle. SPC suggested a slight or 15% severe weather chance
and the primary storm modes are large hail and wind damage early
which become wind damage with the formation of a healthy cold pool
later this evening.
POPs for the forecast tonight are mostly 20 to 30 percent with 40
percent across northwest Nebraska. This might be conservative but
storm activity will have to overcome a 14C 700mb cap across the
Panhandle and the RAP model would suggest no POP at all because of
the cap.
The temperature forecast leans on the guidance blend plus bias
correction plus a couple of degrees across swrn Nebraska. The
convection tonight should help pull the cold front south into ncntl
Nebraska providing a modest cool down Monday. Highs around 90 are in
place across ncntl Nebraska Monday with mid 90s across swrn Nebraska.
Rain chances Monday night have been dismissed by most models with
just the SREF showing development in the Panhandle late Monday. The
models are in good agreement building a fairly strong h700mb ridge
across wrn Nebraska which should produce subsidence and no obvious
trigger is shown aloft by the models. Temperatures aloft at h700mb
are around 14C presenting a formidable cap leaving just a weak
frontal boundary near the Black Hills and of course, the Laramie
range for focus and storm development. Nonetheless, SPC suggested
storms may form across the Panhandle Monday evening and the forecast
carries an isolated POP for this reason.
.LONG TERM...(Tuesday through Sunday)
Issued at 323 PM CDT Sun Jun 13 2021
There is little change in the extended forecast today. The models
are in very good agreement amplifying the subtropical ridge
across NM north into Nebraska this week- Wednesday will be the
warmest day. The upper level ridge will flatten Thursday allowing
a Pacific cold front to move through Nebraska with cooler weather
to follow. The models continue to show h700mb temperatures rising
to near 17C Wednesday...about a 3C bump above Tuesday`s readings.
Highs in the 90s are in place Tuesday which warm a few degrees
Wednesday. Dew points in the lower 60s shown by the model
consensus generate heat indices above 100F and later forecasts at
some point will likely include a heat advisory.
Isolated POPs are in place at times Wednesday night through Sunday
but later forecast may well have to increase these chances. A
stationary front may set up across Nebraska and this would certainly
provide an excellent focus for storm development, especially given
the increase in winds aloft to around 40kt.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 632 PM CDT Sun Jun 13 2021
Scattered thunderstorms will develop and move southeast into
western and portions of north central Nebraska tonight. Chances
are not real high that they will directly impact either the LBF or
VTN sites, but it is possible and a VCTS has been included in the
terminal forecast. Otherwise VFR conditions will prevail outside
of any thunderstorm activity. Winds will generally be 10 kts or
less but will be stronger around any thunderstorm activity.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Taylor
Area Forecast Discussion
National Weather Service Pueblo CO
901 PM MDT Sun Jun 13 2021
.UPDATE...
Issued at 847 PM MDT Sun Jun 13 2021
Updated to end thunderstorm chances for this evening. A few cells
have popped up on the north side of the Palmer Divide, but are
having a hard time sustaining themselves as they drop southeast.
At this time, it does not appear they will make it into northern
El Paso County. Mozley
UPDATE Issued at 550 PM MDT Sun Jun 13 2021
Updated the precipitation chances based on the latest satellite,
radar and guidance. The two areas of concern continue to be the
Palmer Divide and Raton Mesa region. Isolated thunderstorms
continue to pop up off Pikes Peak, and then dissipate as they
shift eastward into El Paso County. MLCAPE values are still
upwards of 1500 j/kg, however, there is quite a bit of CIN across
the region, likely limiting the eastward extent. That being said,
if a storm can get going, there is more than enough instability
and shear for strong updrafts that could produce up to 1.5 inch
hail and 60 mph winds. Down south off the Raton, there is much
less certainty. Moisture is more limited, and MLCAPE under 1000
j/kg and quite a bit of CIN. An isolated strong to severe storm
may also be possible over this area. Thunderstorms should
dissipate with sunset, with dry conditions expected after 8 PM or
so. Mozley
&&
.SHORT TERM...(This evening through Monday)
Issued at 251 PM MDT Sun Jun 13 2021
Currently...
A few small thunderstorms have fired off in El Paso County, while
some spotty cumulus clouds can be seen on visible satellite across
the I-25 corridor. Dewpoints near the Palmer Divide are still near
60, so things are still a fair bit more humid than some models
suggested. Will be keeping a close eye on convective activity over
the next few hours...
The main influence for today`s setup will be the shortwave energy
traveling through the upper-level ridge over our area this afternoon
through tomorrow morning. These conditions will provide some
synoptic scale ascent, while surface flow is expected to be similar
to yesterday. Flow at the surface will mainly be from the east-
southeast, providing moisture, while flow at the mid-levels will be
more westerly, providing some directional shear and advecting dry
air aloft, serving to increase mid-level lapse rates. The main
difference in the setup from yesterday is that the best flow and
moisture will be centered north of highway 50, and our main areas of
interest for severe potential will be Teller, El Paso, and possibly
eastern Fremont and northern Pueblo Counties.
Severe Threats...
Given proper orographics and surface flow, the Raton Mesa and Palmer
Divide will be the two main areas to watch this afternoon-evening.
For the Palmer, short-term models are resolving 2500-3000 J/kg of
CAPE and 30-plus knots of bulk shear near Colorado springs, which
makes sense given that dewpoints have been in the low-60s since 9AM.
A few small thunderstorms have fired off of Pikes Peak and drifted
into El Paso County, but nothing severe has been noted yet. Models
suggest more storms should fire within the next few hours, lasting
through 6-7PM. Looking at forecast soundings, there are still some
decent dewpoint depressions expected near the surface, and with
inverted-V soundings present at several locations and moisture
seemingly more high-based, today`s primary threat will likely be 60-
70 mph wind gusts and hail up to 1.5 inches. Similar to yesterday,
LCLs are on the high side over the I-25 corridor, and given the high-
based moisture the chance of a tornado is fairly low, although if
one were to happen it would be over the Palmer Divide where LCLs are
the lowest.
The Raton Mesa overall is looking a bit less favorable for severe
weather today. Models are resolving between 700-1500 J/kg of CAPE
and around 30 knots of bulk shear. However, moisture does not seem
to be nearly as bountiful and LCLs are closer to 10 kft in most
places. However, should a storm overcome these limitations and fire,
it would likely occur between 4-6PM near Trinidad, with 60mph wind
gusts and 1-1.5 inch hail possible. The threat of tornadoes in that
area is near zero.
Finally, a few storms could also fire off the Wet Mountains a bit
later in the afternoon as well. Models are in disagreement on this,
but given the ambient moisture and CAPE in the area, the possibility
cannot be ruled out. However, there is low confidence that these
thunderstorms would be able to reach severe status.
Forecast Confidence...
Over the last several days, forecast models have been handling
convective activity fairly poorly. The HRRR has had the tendency to
overmix the atmosphere, resulting in incredibly dry and
precipitation-free environments. Overall, the NAM and NAM Nest, as
well as ensemble solutions, seem to be handling these situations
more appropriately. This reveals several potential solutions for
this type of situation; where there is ample moisture and
instability, but it is high-based. Additionally, there is a notable
cap over the eastern plains that should prevent convection entirely,
and although shear is sufficient, overall there is fairly weak large-
scale forcing to help thunderstorms along. If storms manage to
overcome these obstacles, they tend to be stronger to severe, but
some models tend to lean towards solutions where the inhibiting
factors win out. Given recent trends over the last several days,
combined with increased confidence in a more moisture-rich
environment than models suggest (which tend to run a bit dry,
anyways), forecast confidence in convection over Teller and El Paso
Counties this afternoon-evening is moderately high. Confidence on
the Raton Mesa convection is moderate, but still possible, while the
confidence on convection coming off the Wet Mountains into Pueblo
County is low. Even though we have higher confidence in storms on
and near the Palmer Divide today, the strength and extent of the
storms will depend on how soon convection can overcome these
limiting factors, and will have to be closely monitored closer to
initiation time. Storm motion today will also be tricky, as storms
have tended to be very slow-moving the last 48 hours, which models
capture especially poorly. Given the mean flow, storms moving to the
northeast through our area of interest is most likely at this time,
although propagation of updrafts will likely differ storm to storm.
Monday...
Moisture is still expected in excess over the far eastern plains on
Monday, and with daytime heating in no short supply under the upper-
ridge, another round of convective storms is anticipated for the
afternoon-evening hours. However, like today, there will be a cap in
place over most of the area, so confidence in this outcome is still
in flux. The best environment for storms will be to our east, where
there is more CAPE and less instability. However, a few storms could
still fire off the southern Sangres tomorrow before moving east into
better air.
Otherwise...
Outside of the general severe threat, temperatures today and
tomorrow will be hot once again, hitting mid-high 90s over most of
the area, with near-record breaking temperatures expected in several
places. Outside of convective areas, there will just be a few clouds
around, mostly sunny, which will assist in the daytime heating, and
winds should stay from a generally southeast direction and slightly
gusty in the afternoon hours.
.LONG TERM...(Monday night through Sunday)
Issued at 251 PM MDT Sun Jun 13 2021
...Hot with isolated mountain thunderstorms at times...a potential
uptick in thunderstorms still advertised for late week into next
weekend...
Upper high stays locked in across the Rockies and 4 Corners region
through mid week with low levels drying out in and near the
mountains. Mid and high based moisture will gradually increase
within the upper high. This will support isolated afternoon and
evening thunderstorms over and near the mountains both Tuesday and
Wednesday. Inverted V soundings suggest primary storm risks will be
lightning and gusty outflow winds but only spotty light rainfall.
Meanwhile, high temperatures will climb to record to near record
values both days.
Energy moving through southern Canada and the northern U.S Rockies
will eventually send a cold front into the southeast plains...mostly
likely in the Thursday night/Friday time frame with EC leaning
towards the later side. With moisture still cycling through the
upper high across CO, the mountains will see isolated to scattered
thunderstorms each day with a better chance for some spotty wetting
rains as surface dew points come up. The plains will see an uptick
in thunderstorms Friday into next weekend with the possibility of
strong to severe thunderstorms on Friday or Saturday if sufficient
low level moisture advects back westward. Otherwise with another
day of record to near record heat on Thursday, temperatures will be
dropping back closer to climatological averages...though still
slightly on the high side. -KT
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 251 PM MDT Sun Jun 13 2021
VFR conditions expected over KALS, KCOS and KPUB over the next 24
hours. Winds this afternoon will be gusty up to around 25 mph, from
the southeast at KALS and the southeast at KCOS and KPUB. There is a
chance that thunderstorms could develop near KCOS and KPUB after
about 22Z this afternoon, with confidence at KCOS being much higher
than KPUB. However, exact storm placement will be tricky today, so
left KCOS at VCTS for now. Winds will weaken after nightfall and
become diurnally driven.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...MOZLEY
SHORT TERM...GARBEROGLIO
LONG TERM...KT
AVIATION...GARBEROGLIO
Area Forecast Discussion
National Weather Service Blacksburg VA
1029 PM EDT Sun Jun 13 2021
.SYNOPSIS...
A front enters the area late tonight, pushing to the coast by
Tuesday. Drier air works in behind this system for much of the
coming week. The next chance of showers and thunderstorms
returns for next weekend.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 1025 PM EDT Sunday...
Bowing line of storms continues heading south through the
south-central portions of the forecast area. This line is
expected to continue heading south, and trend weaker in time.
Most of the precipitation behind this feature is light rain that
will continue for an hour or two behind the exiting line. Little
if any rain is expected across the area by 200 AM Monday.
Fog is expected to develop overnight. Some areas could be
locally dense.
As of 630 PM EDT Sunday...
Small adjustments made to thunderstorm arrival...
The forecast on a whole will not be changed a great deal. We are
still expecting the ongoing thunderstorm activity southeast of
Covington to head southeast, and storms across central WV to
continue heading southeast into the Watch area. Have made minor
adjustments to the hourly grids regarding the timing of the best
chances of stronger storms entering the Watch area.
As of 500 PM EDT Sunday...
Severe Thunderstorm Watch in effect through 10PM for
northwest part of the forecast area...
Forecast update in the near term reflects a more robust coverage
of showers and storms around the Lexington region over the next
couple of hours. Looking ahead into the evening hours, we will
become more concerned with activity that is currently across
northern sections of West Virginia. Showers and storms are
expected to head south following an instability axis and arrive
within the new Severe Thunderstorm Watch area with in the 7pm
to 9pm time frame, then progress southeast into the region. The
greatest severe threat will be damaging winds. Also, locations
that receive multiple rounds of heavy rain producing showers or
thunderstorms could be a candidate for localized flooding or
flash flooding. We will continue to monitor for both severe and
flooding threats.
As of 145 PM EDT Sunday...
Threat of severe storms, some heavy rain along a line this
afternoon/evening...
High-res convective allowing models are somewhat different on
timing/strength of the convective clusters that extend eastern Ohio,
northern WV into the Shenandoah Valley north of Staunton this
afternoon.
The visible satellite shows limited vertical development in the cu
field in our forecast area. This shows that the 12z HREF/Nested NAM
and 16z RAP are overdone on convection as they were all showing
storms firing up in the Alleghanys from Greenbrier to Bath by now.
The 16z HRRR seems to have a better handle on what is occurring and
will lean toward its solution this afternoon, though the others have
the same flavor on lining up convection further north and showing a
scattered to broken line of storms moving south into our Alleghany
Highlands/Greenbrier Valley area east toward the Blue Ridge between
19z-22z, then shifting to the Roanoke/New River Valleys between 22-
01z, in two clusters, one pre-frontal the other more along an upper
wave.
Instability this afternoon is high but airmass is "drier" over us
with pwats of 1 to 1.3 inches. SBCAPEs are running above 2000 J/kg
in the mountains, and even higher over KY where temperatures are
warmer. Low cloud cover has slowed the destabilization further east,
but DCAPES are higher in the 1000-1300 J/kg range.
With instability present/available, am concerned we could at least
see some potential for stronger winds across our northern CWA later
this afternoon, though the better shear exists further north.
As we head through the evening, expect some weakening as this line
moves south through the NRV and Mountain Empire east to the piedmont
with models showing convection breaking up and ending late, though
some models are still showing lingering showers into the
overnight.
Will keep pops in the likely range north of I-64 this afternoon, to
chance pops along/west of the Blue Ridge, as a few showers/storms
could fire along the ridges after 4pm. By dusk ramp trying to time
the line of convection but also showing areal coverage lessening, so
will have likely pops from the Mountain Empire through the New and
Roanoke Valleys, northeast toward Lynchburg, tailing off the
low chance along/south of the Va/NC border.
As the vort associated with convection pushes off to the southeast
overnight, look for some clearing, but also have potential for low
clouds/fog again, especially where it rains, but confidence is low
on this. Will have more clouds in WV and the piedmont, with less in
along the Blue Ridge by dawn Monday with fog most everywhere in the
2 to 5 mile visby range.
Monday should be drier, as lower dewpoints at least work to the
mountains after frontal passage. There looks to be another wave
along the front moving across central Virginia Monday afternoon, but
overall a west-northwest flow increasing aloft to dry the airmass
out, so keeping any slight chance pops east of Lynchburg to Danville
line, with most places seeing plenty of sunshine but staying warm
with highs in the lower 80s mountains to near 90 east.
Forecast confidence is high on threat of showers/storms through this
evening, though average on how high pops to go and how far south
this line makes it. Average confidence on fog/low clouds late
tonight but high confidence on a drier and sunnier Monday.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 200 PM EDT Sunday...
Shower chances trend down as high pressure builds in...
An upper trough sets up over much of the east coast of the CONUS,
anchored on a cutoff upper low in southeastern Canada. This will
advect some cooler, drier air into the area and help decrease the
chances of precip through the middle of the week. In addition,
higher surface pressure begins to settle in, arriving from the
midwest. The center of the surface high will be near OH and MI by
Wednesday night. The high pressure will also help to suppress
showers, but the possibility for some isolated showers exists
through Wednesday afternoon/evening, especially over the mountains,
but most will remain dry.
With largely clear skies and a bit of a drier air mass, expecting
diurnal temperature swings to be 20+ degrees as there is no cover to
block insolation during the day, no showers to cool daytime temps,
and little cover to prevent radiative cooling at night. This will be
more evident towards the mid-week; by Wednesday night, expecting
lows to drop into the 40s west of the Blue Ridge, 50s east. Highs in
this portion of the forecast will generally be in the mid 70s west,
mid 80s east.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 200 PM EDT Sunday...
Dry conditions last through Friday, but an approaching cold
front ends the calm weather this weekend...
High surface pressure will keep precip at bay through Friday.
Meanwhile a surface low moves through southern Canada and
towards the Great Lakes. That low has an associated cold front
trailing below it that approaches us by Saturday morning. The
surface high pressure that had been over us will slide off the
coast and synoptic flow will turn to the south/southwest ahead
of the front. This will warm things up for the weekend. Pre-
frontal showers will begin forming by Saturday afternoon and
should continue through Sunday.
Temperatures will start around or just below normal for the season
and rise to a few degrees above towards the end of the forecast
period.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
As of 715 PM EDT Sunday...
Strong to severe thunderstorms will be impacting at least TAF
sites KLYH, KROA, KLWB, KBLF, and perhaps KBCB through 02Z/10PM.
Variable wind speeds with gusts nearing 50kts are likely in and
around each of these airports as the storms move through. Also,
anticipate quick changes and both ceiling height and visibility
thanks to these storms as well.
It`s a bit more uncertain if KDAN will see any substantial
activity, but there likely will be at least scattered showers
near KDAN around 01Z-03Z/9PM-11PM.
Once the precipitation clears, look for areas to trend towards
decreasing visibility as light fog develops. Most areas with
fog will be in MVFR range, but pockets of IFR or lower are
possible, especially in the river valleys and where the heaviest
rain falls this evening.
On Monday, drier air will work its way into the region with
conditions quickly improving to VFR by mid-morning, and
remaining that way through the day.
Confidence in the above aviation scenario is moderate to high.
The biggest question will be the next few hours with the impacts
of the strong storms moving through the area.
Extended Aviation Discussion...
There is a low chance of thunderstorms Tuesday afternoon in the
mountains. Otherwise mainly VFR into Friday outside of any late
night fog in the mountains with high pressure settling in over
the region.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...AMS/WP
NEAR TERM...DS/WP
SHORT TERM...VFJ
LONG TERM...VFJ
AVIATION...DS/WP
...Update to aviation forecast discussion...
.DISCUSSION...
Issued at 229 PM CDT Sun Jun 13 2021
Upper level ridging remained centered over the southwestern U.S.
per the 19Z water vapor imagery with the ridge axis extending into
the northern Rockies. A closed upper low was off the Pacific
Northwest coast, and an MCV was noted over southwestern OK
generated from last night`s convection. At the surface, high
pressure continued to nose into northeast KS providing some
relatively dry air and light winds. The low level moisture axis
was shifted west over south central and western KS as a result.
For tonight quiet weather should continue due to a lack of forcing
for vertical motion and general subsidence within the upper ridge
axis. With clear skies and light winds, lows are expected to fall
into the lower and middle 60s. Chances for ground fog look pretty
small since afternoon dewpoints have already mixed out into the
middle and upper 50s.
Monday could see another MCV this time move across northeast Kansas
from convection that has developed over SD. The 15Z RAP shows a nice
compact vort max moving through the area during the afternoon and
other 12Z guidance also indicates this potential to varying degrees.
While the RAP develops isolated showers, the NAM and GFS fail to do
so because of a dryer airmass and less instability. And the RAP
doesn`t get much support from the HREF, although the 12Z HRRR has
some isolated precip moving into north central KS early in the
afternoon. Much of the larger scale models keep things dry except
for the GFS which waits for the MCV to pass before developing
storms. This doesn`t make much sense and was not given much weight
in the forecast. So with the majority of guidance keeping a dry
forecast, have POPs at 10 percent across north central KS where
there could be just enough moisture as the MCV passes for an
isolated storm to pop up. Highs Monday look to be in the lower and
middle 90s as models warm the airmass slightly.
For Tuesday through Thursday, the main story is the heat building
into the forecast area. Models show good warming at 925 for
Wednesday and Thursday with western parts of the forecast area
potentially hitting triple digits. For now the National blend of
models keep the higher dewpoints southeast of the area with mixing
in the afternoon lowering the moisture content. This keeps apparent
temps below 105 Thursday afternoon. But this will be something to
keep an eye on.
Models prog a boundary moving into the area and hanging up across
the region Thursday night and through next weekend. This coincides
with the upper ridge breaking down to allow the front this far
south. So the good news is there should be a cooling trend for highs
even if there remains some differences in the location of the
boundary. But the 12Z ECMWF has started to show the boundary moving
into the forecast area. This may provide a focus for showers and
storms even though the better westerlies look to remain north of the
forecast area. So the forecast has some small POPs sprinkled
throughout the forecast for the end of the week and the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 617 PM CDT Sun Jun 13 2021
High pressure overhead will keep VFR conditions with clear skies
and light to calm winds overnight, remaining light through the
day tomorrow.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Wolters
AVIATION...Picha