Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/18/20
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
536 PM MDT Wed Jun 17 2020
.AVIATION...
00Z TAF CYCLE
Upper trough moving through the Great Basin with sw-wly flow aloft
over NM. At 23Z dryline starting to push back wwd with isold
convection possible along the boundary before 02Z. Short term models
indicate the dryline may reach as far west as the Pecos Valley by
06Z. Sfc lee trough to shift ewd with nly wind shift over ne NM aft
10Z. Areas of MVFR vsbys/cigs in FU/HZ are possible over portions of
wrn and central NM between 06Z-16Z.
&&
.PREV DISCUSSION...230 PM MDT Wed Jun 17 2020...
.SYNOPSIS...
The closed low over eastern Idaho and the trough associated with it
will lift slowly northeast through Thursday. Another weaker trough
will impact NM Friday. A back door cold front will push south and
west across the east Thursday night into Friday, resulting in a
cooler day across the east Friday afternoon. Some showers and storms
will be possible during this time, mostly in the northeast. Wind
shifts each day and night in the northeast will keep this area as a
focus for a few showers and thunderstorms this weekend into next
week. The strongest wind shift/backdoor cold front/dry line will be
next Monday night in the east. Enhanced convection is expected in
the northeast Tuesday and much of the east Wednesday.
&&
.DISCUSSION...
SHORT TERM...(WEDNESDAY NIGHT THROUGH THURSDAY NIGHT}...
Dry southwest flow has strengthened this afternoon with gusts
ranging from 25 to 50mph across much of western and central NM.
Active fire plumes in AZ are starting to build this hour and their
strengths and trajectories will be closely monitored tonight as
southwesterly to westerly flow brings them into west-central NM late
this evening and throughout central NM by Thursday morning. The big
question is just how much smoke settles to the surface overnight.
Have included mention of smoke in the forecast across a good portion
of western and central NM overnight into Thursday morning before
mixing out by mid-day. HRRR near-sfc smoke model is depicting a
repeat situation for Thursday night into Friday morning, which makes
sense given the continued WSW flow from AZ into NM.
Elsewhere, there is some cu over the lower Pecos River Valley over
DeBaca and Chaves Counties this afternoon. These could produce a few
high-based showers this afternoon resulting in some erratic gusty
winds from Roswell to Fort Sumner. The only chance for stronger
storms lays along the TX border from I-40 southward through Curry
and Roosevelt Counties. There remains a marginal risk for a few of
these storms becoming severe, but these storms will quickly move
east into Texas.
Meanwhile, an embedded shortwave within a larger troughing pattern
over the western CONUS will eject over the Northern Great Plains
tonight with relaxing southwest flow resulting through NM Thursday.
This will bring down winds a notch for Thursday and also send down a
backdoor cold front along the front range of the Rockies. This
backdoor front enters northeastern NM Thursday with a chance for
some showers, and more likely a low stratus deck over northeastern
NM heading into Friday morning and the Long Term period.
24
LONG TERM...(FRIDAY THROUGH WEDNESDAY)...
Behind the cold front from Thursday night, Friday will be cooler in
the east. Showers and thunderstorms are forecast from the Sangre de
Cristo Mountains to the east central plains, the most widespread in
the northeast. This convection will continue into Friday night. The
weekend and next Monday will be drier and warmer, with the only
convection in the far northeast each afternoon. Another back door
cold front will impact eastern NM Monday night with slightly cooler
weather for Tuesday and Wednesday. Showers and thunderstorms will be
more widespread Tuesday in the northeast and from the central
mountains to east central NM Wednesday.
40
&&
.FIRE WEATHER...
Critical fire weather conditions will remain over west-central and
northeastern NM through the rest of this afternoon as stronger
southwest winds have mixed down the surface. Peak gusts of 25 to 45
mph will result combining with MinRHs dipping to the single-digits
in some spots. Smoke plumes from active fires in AZ will need to be
closely monitored through tonight into Thu morning as this smoke has
the potential to settle over a good portion of western and central
NM. SW to W flow remains over NM Thu, but to a lesser degree. This
will keep western and central NM in play for another round of smoke
concerns heading into Fri morning. Low-level moisture sets up
further east Thu morning allowing for more widespread poor
recoveries tonight.
The exception will be behind a backdoor front entering far
northeastern NM Thu morning, pushing to the central mountain chain
Fri morning. This will bring better overnight recoveries across the
east and a chance for showers/storms through northeastern NM along
and east of the Sangre de Cristo Mountains. Transport winds shift W
then NW this weekend with the dryline swashing back and forth
through the eastern plains each night. This should reduce smoke
concerns for the weekend heading into next week. Winds will remain
the limiting factor for any critical fire weather conditions during
this time.
24
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 7 PM MDT this evening for the following
zones... NMZ103>105.
&&
$$
Area Forecast Discussion
National Weather Service La Crosse WI
1058 PM CDT Wed Jun 17 2020
.SHORT TERM...(This evening through Thursday)
Issued at 225 PM CDT Wed Jun 17 2020
Tonight, low temperatures will cool into the 60s, but another
pleasant day is on tap. Tomorrow afternoon, temperatures will
climb back into the upper 80s. Dew points will remain nearly
steady around the lower 60s and upper 50s. Cloud cover will be on
the increase tomorrow afternoon ahead of the incoming cold front
and associated precipitation.
Depending on the rate of progression of both the upper level
short wave and associated surface cold front, shower and storm
chances begin increasing late Thursday afternoon around 00z. In
general, a band of shower/storms is expected to slowly track
eastward across the region overnight Thursday into Friday
morning.
There could be a few strong storms, but the severe risk is low at
this time. There is some instability to work with Thursday evening,
but the deep layer shear looks to remain off to the west farther
behind the surface front. Widespread flooding potential appears
low as these past few days have been dry. Local heavy rain is
possible with the stronger, pulse type storms and precipitable
water values ranging from 1.5" up to 2.0".
.LONG TERM...(Thursday night through Wednesday)
Issued at 225 PM CDT Wed Jun 17 2020
For Friday, a few lingering showers from overnight could last
into the afternoon hours. High temperatures will be around 10
degrees cooler than Thursday. By the evening, the front will be
further off to the east. Another shortwave trough coming out of
the southern plains heading northeast nearly along the remains of
that surface frontal boundary will bring additional chances for
showers and storms over the weekend.
Over the first half of the work week, a nearly stacked low looks
to wrap up and slide over southeastern Ontario into the Great
Lakes region. With the area under northwesterly flow, small
chances for precipitation are introduced as pieces of short wave
energy pass through this wave pattern.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1058 PM CDT Wed Jun 17 2020
Relatively quiet VFR conditions are expected through Thursday
afternoon. A cold front will be approaching from the west and with
a tight pressure gradient ahead of this front, look for gusty
south winds for much of the day at both sites. The front looks to
be close enough to produce a mid to high level VFR ceiling at both
sites Thursday evening with some convection expected to be near
KRST. The 18.00Z NAM has come in with a bit slower solution
holding any rain off until mid-evening and the latest runs of the
HRRR are also trending toward a slower solution or having the
leading activity breaking up as it initially comes in. With this
uncertainty, will only add a VCSH to KRST for now.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...Peters
LONG TERM...Peters
AVIATION...04
Area Forecast Discussion
National Weather Service Bismarck ND
1102 PM CDT Wed Jun 17 2020
.UPDATE...
Issued at 1100 PM CDT Wed Jun 17 2020
We will leave Dickey county in the watch through Midnight.
Otherwise will cancel Lamoure.
UPDATE Issued at 817 PM CDT Wed Jun 17 2020
The surface trough and associated low pressure system across
eastern North Dakota has moved slowly east. The line of convection
now looks like it will remain east of most if the Jame River
Valley. So we will cancel most of the severe thunderstorm watch
except for Dickey and Lamoure counties. A thunderstorm or two
could clip the far eastern portion of these counties this
evening.
Otherwise, most of west and central North Dakota was mostly
clear, while the showers across Montana were slower than forecast
to move east into western North Dakota.
The mid level water vapor loops show a circulation across
southwest Wyoming that will move northeast tonight. This feature,
in the relatively fast southwest flow aloft will bring some
mid level vertical motion across central South Dakota this
evening, which will move northeast into North Dakota later
tonight. We expect further showers and thunderstorms to develop
and move north into south central North Dakota late tonight, This
is not expected to be severe, but may spread showers and a few
thunderstorms into the south. So we cleared the precip over much
of the west and central this evening, then brought chances back in
later tonight, mainly south central, east of Bismarck.
UPDATE Issued at 521 PM CDT Wed Jun 17 2020
This update for Severe Thunderstorm watch 282 until 11 pm CDT.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 249 PM CDT Wed Jun 17 2020
Severe thunderstorm potential in parts of south central ND into
the James River valley is our focus through this evening.
As of 19 UTC, a nearly stationary frontal zone extends from near
Linton to Carrington. Elevated convection continues near and to
the cool side of the boundary, with low-level theta-e advection
ongoing in the moist sector where surface dewpoints have risen
into the middle and upper 60s F. Steep midlevel lapse rates are
contributing to moderate to strong instability with MLCAPE from
2000-3000 J/kg, and model simulations and RAP objective analysis
data suggests MLCIN is quickly becoming minimized with boundary
layer heating and moistening. Forecast soundings are strongly in
agreement that a warm nose near 700 mb will persist until close
to 00 UTC, which along with initially weak confluence along the
stationary boundary casts some doubt on the timing of surface-
based convective initiation. In contrast, low-level water vapor
imagery has been showing a subtle midlevel impulse embedded in
southwest flow aloft that is approaching central SD, and recent
visible satellite imagery reveals subtle cirrus associated with
this impulse near Phillip, SD, as of 1930 UTC. Extrapolation of
this feature and in particular its associated cirrus -- which
likely reflects ascent and cooling aloft required for convective
initiation -- has it reaching the frontal zone in south central
ND between 2130 and 2230 UTC. Shallow cumulus near the deeper
moist layer near the frontal zone and the elevated convection in
its vicinity are contributing to notable differential heating and
the augmentation of the low-level ascent and the approach of the
aforementioned impulse aloft is increasing our confidence in the
initiation of surface-based thunderstorms initially near an axis
from Linton and Napoleon toward Carrington around 22 UTC.
Some uncertainty remains in the timing of convective initiation
given the lingering warm nose aloft in forecast soundings and a
disparate set of solutions from CAMs, including the HRRR, which
has held off initiation until closer to 00 UTC and mainly east
of our forecast area. However, that`s a known bias of the HRRR,
and our confidence in the timing and evolution is increasing as
the previously-mentioned observational trends come in focus.
Once storms develop, they will be propagating in an environment
characterized by effective shear on the order of 30-40 kt, which
supports both organized multicells and potential supercells with
the magnitude of instability present. Given a modest orthogonal
component of deep-layer shear vectors to the frontal zone, some
initially-discrete supercell modes are possible, though weaker
high-level flow and right-moving supercell motion vectors from
~230 degrees -- closer to the orientation of the boundary -- do
suggest messy modes could evolve in time. Still, the CAPE-shear
setting and steep lapse rates continue to support advertising
hail up to golf ball size, further advocated by analysis of SPC
SARS output. Some explicit sounding analog matches do show
potential for larger hailstone sizes given the large instability
and high inflow-layer theta-e, but the potential for messy modes
means we are not advertising that at this juncture. We will also
continue to message damaging wind gusts up to 70 mph. There is a
non-zero tornado risk given 0-1-km SRH increasing to between 100
and 150 m2/s2 in the James River valley by early evening, but we
have refrained from explicitly mentioning that at this time with-
out stronger deep-layer shear and marginally-favorable MLLCL
heights, along with potential for messy storm modes.
Based on HREF-SREF blended severe-storm timing guidance, we feel
that the risk of severe thunderstorms will subside by 06 UTC.
Otherwise, the larger middle- and upper-level trough is forecast
to lift northeast into southern Canada by Thursday as it evolves
into a slow-moving low aloft. A jet core and embedded shortwave
trough rotating around that feature could bring another round of
showers and a few thunderstorms to south central areas overnight
and early Thursday morning. Ultimately, this evolution will also
drive another cold frontal zone eastward by Thursday and that is
forecast to lead to a breezy day. We weighted the forecast toward
the higher, MOS-based wind guidance on Thursday. A cyclonic flow
regime could yield low-topped convection, but we relegated PoPs
mainly to southwestern ND where forecast soundings suggest less
influence from a midlevel subsidence inversion than elsewhere
during the day.
.LONG TERM...(Thursday night through Wednesday)
Issued at 249 PM CDT Wed Jun 17 2020
We will be in a seasonable, albeit slightly cooler pattern on the
whole through the long term, with a few chances of showers and
thunderstorms, mainly this weekend.
On Thursday night, the 12 UTC model suite is consistent showing a
strong surface high moving through the Northern High Plains, with
light winds and a subsidence regime supportive of lows likely in
the 35 to 40 F range in parts of southwestern ND. We will need to
consider the potential for frost in this setup.
Thereafter, the upper-level low in southern Canada will slowly be
shifting eastward amid synoptic-scale blocking. The cyclonic flow
on the southern flank of the low and potential impulses embedded
in it will bring some chance of showers and storms this weekend,
with a slow drying trend early next week. The 12 UTC ECMWF and GFS
suggest a non-zero risk of stronger storms Saturday, though the 00
UTC GEFS-based CIPS analog severe probabilities suggest relatively
low confidence in that. The overall flow may become less cyclonic
by early next week, leading to lower precipitation probabilities
in ensemble guidance. Highs through the period will generally be
in the 70s to lower 80s F.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 817 PM CDT Wed Jun 17 2020
Hazards to aviation tonight include thunderstorms across south
central North Dakota. Also MVFR conditions are expected to
develop across the western and northern North Dakota late tonight
and Thursday associated with a cold front.
At 8 PM CDT, the cold front extended across southern Canada. The
front will move southeast and bring some MVFR ceilings into the
region late tonight and Thursday.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...WAA
SHORT TERM...CJS
LONG TERM...CJS
AVIATION...WAA
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
921 PM CDT Wed Jun 17 2020
.UPDATE...
Storms that developed over the Trans Pecos earlier this afternoon
have been able to hold together and currently tracking southeastward
along the Rio Grande, with majority of the convection on the Mexican
side of the border. Based off of current radar trends, went ahead
and included a mention of thunder for our far western areas along the
Rio Grande. Also within the past half hour, an isolated cell has
developed over Crystal City. This storm has had hints of possible
small hail and frequent lightning. Sounding from DRT this evening
shows fairly steep mid level lapse rates for June ~ 7 C/km. High res
guidance is still out to lunch on this activity, so current thinking
is this activity should dwindle with most of it staying on the other
side of the border over the next hour or two.
&&
PREV DISCUSSION... /ISSUED 624 PM CDT Wed Jun 17 2020/
AVIATION...
All sites VFR through the remainder of the the evening. Complex of
storms NW of Del Rio should dissipate before reaching DRT but the
latest HRRR run shows some activity could persist. Will have to
monitor, no mention of thunder in for now. MVFR ceilings develop
across all sites tonight and scattered out late Thursday morning.
Southeast winds should remain at or below 12 knots tomorrow. VFR will
prevail through the remainder of the period.
PREV DISCUSSION... /ISSUED 247 PM CDT Wed Jun 17 2020/
SHORT TERM (Tonight through Thursday Night)...
Extensive cumulus field over the western half of South Central Texas
today, but less convection than the last couple of days showing the
upper ridge has strengthened. We don`t expect much change in the
pattern during this period. The upper ridge will tilt a bit to the
east, but remain in place over Texas. The low level flow will
continue to be from the southeast keeping moist air in place. There
is some model disagreement about convection. Most of the models are
dry, but the GFS continues to produce showers during the daytime
hours Thursday. We have gone with the consensus dry forecast through
this period. We have also gone a couple of degrees above the model
blend on high temperatures Thursday since it has consistently
underperformed with it`s cooler forecast. Low temperatures both
tonight and Thursday night will be near seasonal normals.
LONG TERM (Friday through Wednesday)...
Friday continues the pattern of weak upper ridging to offset
localized moisture pooling. Thus another day of a few showers and
very isolated storms favors areas around San Antonio metro and areas
to the SE toward the Coastal Bend where low level moisture
convergence appears to focus. By Saturday 500 mb heights fall to
form a weak trough over Central TX while low level moisture continues
to funnel north from the Gulf. There could be some pockets of more
organized storm clusters moving inland, particularly over the Coastal
Prairies. Upstream NW flow continues a weak troughing pattern to
leave a very similar picture for rain chances on Sunday. The NW flow
pattern only shows up in the 500 mb winds, so will not show any
interest in nighttime rain chances for Saturday night or Sunday night
for now.
By Monday morning mid-level subsidence begins to build over West TX
and nudges the isolated PoP areas eastward, and the middle of next
week is trending more and more stable. The re-establishment of high
pressure aloft should also lead to hotter temperatures for the work
week, and without a significant change in low level winds expected,
higher heat index values as well.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 73 93 72 93 72 / 0 - 0 20 -
Austin Bergstrom Intl Airport 70 93 72 93 71 / 0 - 0 20 -
New Braunfels Muni Airport 72 92 72 92 71 / 0 - - 20 -
Burnet Muni Airport 71 91 71 91 70 / 0 - 0 10 -
Del Rio Intl Airport 76 97 75 97 75 / 20 10 10 10 10
Georgetown Muni Airport 72 94 72 93 71 / 0 - 0 10 -
Hondo Muni Airport 74 93 72 94 72 / 10 10 10 20 10
San Marcos Muni Airport 72 93 71 93 70 / 0 - - 20 -
La Grange - Fayette Regional 72 94 72 93 71 / 0 - 0 20 -
San Antonio Intl Airport 74 92 74 92 74 / - 10 10 20 10
Stinson Muni Airport 74 91 74 92 74 / - 10 - 20 10
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...EWilliams
Long-Term...Platt
Area Forecast Discussion
National Weather Service North Platte NE
624 PM CDT Wed Jun 17 2020
.SYNOPSIS...
Issued at 312 PM CDT Wed Jun 17 2020
A very amplified H5 pattern was noted across the CONUS
this morning. Closed low pressure remained entrenched over the
Carolinas with a trough extending south into Florida. High pressure
was located north of the low over Lake Huron and southern Ontario.
Further west. a closed low was located over eastern Idaho with a
trough extending to the southwest into northern Nevada. A broad
shield of cloud cover extended north and northeast of the low into
western Wyoming, Montana and Idaho. At the surface, a stationary
front was oriented from northeastern North Dakota, south into
central South Dakota and the Panhandle of Nebraska. A dryline has
developed over eastern Colorado over the past couple of hours and
was oriented from just east of Holyoke Colorado, south along the
KS/CO border. East of the frontal boundary, winds were southerly
across western and north central Nebraska this afternoon and
temperatures were generally in the lower to mid 90s.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 312 PM CDT Wed Jun 17 2020
The main forecast
challenge in the near term is thunderstorm and severe chances
tonight. By 4 PM CT, the before mentioned dry line will surge to the
east and northeast into far SW Nebraska. This dryline bulge,
forecast to be INVOF Perkins, Keith and western Lincoln county at 4
PM CT is expected to be the focal point for thunderstorm
initiation late this afternoon. The latest NAM12 soln, NAM Nest
and several recent runs of the HRRR initiate convection in this
three county area around 5 PM CT this evening. Felt confident
enough in this forecast, to drop pcpn chances further south into
far SW Nebraska with the previous forecast update. Once storms do
develop, they will track quickly north northeasterly given the
current fcst H5 winds. As storms track to the north northeast into
the Sandhills and north central Nebraska, they will encounter
better moisture and increasing deep layer shear as they traverse
north, leading to an increased threat for severe storms. As for
severe mode tonight, strong winds appear to be the main threat
given the inverted V type soundings. Marginally severe hail
appears possible but very large hail not, given the very high
freezing levels. The cold front track across central portions of
the forecast area by late evening, clearing the forecast area
Thursday morning. The threat for showers and thunderstorms will
continue into the overnight, mainly over north central into
northeastern portions of the forecast area. Some showers may
linger Thursday morning in the eastern forecast area INVOF the
exiting front. The frontal boundary will then stall just off to
the east of the forecast area for Thursday. Inherited forecast had
a mention of tsras in the far eastern forecast area Thursday
afternoon/early evening and couldn`t rule this out given the
latest NAM12/GFS soln. Feel the threat for showers and
thunderstorms, will shift east of the forecast area after sunset
Thursday evening.
.LONG TERM...(Friday through Wednesday)
Issued at 312 PM CDT Wed Jun 17 2020
Surface high pressure will
build into the Dakotas and northern Nebraska Friday. South of this
feature, easterly winds will develop, leading to upslope conditions
and cooler temps across the forecast area. With expected clouds and
easterly winds, temperatures will struggle to get out of the 70s
Friday. Late Friday, an upper level trough will lift into the
central Rockies. Downstream of this feature, showers and
thunderstorms are expected to develop along the front ranges of
Colorado and Wyoming and over the western Nebraska Panhandle. This
will be in the vicinity of a surface boundary and weak theta E
ridging in these areas. Better chances for more widespread rain will
arrive Friday night into Saturday morning as the trough aloft enters
the front range Friday night, emerging into western Nebraska
Saturday morning. This activity will then shift east of the area
Saturday afternoon into Saturday evening. For Sunday and beyond,
northwesterly flow will develop aloft as upper level low pressure
intensifies over the upper Great Lakes and southeastern Canada.
Temperatures in this flow regime will be seasonal with highs in the
middle to upper 80s. Precipitation chances will be limited in this
flow regime with mainly dry conditions expected. Beyond Wednesday,
early indications are that ridging will build east of the Rockies
late next week, leading to the development of hot and dry
conditions.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 623 PM CDT Wed Jun 17 2020
For the KLBF terminal: Expect VFR conditions over the next 24
hours. There will be a threat for low level wind shear from 04z
through 10z tonight with wind speeds of 50 KTS 1500 FT AGL. For
the KVTN terminal: Thunderstorms are expected to develop across
north central Nebraska after 01z. At the terminal strong storms
are expected from 01z to 05z Thursday. Wind gusts to 40 KTS and
ceilings around 2000 FT AGL is possible. The threat for
thunderstorms will come to an end after 06z Thursday.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...Buttler
Area Forecast Discussion
National Weather Service Marquette MI
727 PM EDT Wed Jun 17 2020
.SHORT TERM...(This evening through Thursday)
Issued at 349 PM EDT WED JUN 17 2020
GOES WV imagery and RAP analysis highlight a tilted quasi-omega
patterned, with a mid/upper level low over the northern Rockies and
another over the southeast. At the surface to the west, a slow
moving cold front has inched a little closer, kicking off convection
in central North Dakota along the boundary. Between these cutoff
lows, ridging extending from New England to the southern Plains has
kept conditions dry over the Upper Great Lakes. Aside from some
stray cirrus clouds over Lake Superior and parts of the Keweenaw this
morning, its been a cloud free day. The clouds were associated with
overnight convection over Ontario that got caught up in the
anticyclonic flow. Temps have climbed into the 80s in the west and
in the Keweenaw while in the east inland temps have climbed to near
80 so far. By the lakeshores, temps have been cooler in the 70s
except by Lake Michigan where temps have topped out so far in the
60s. The exception to the lakeshore temps statement has been those
prone to downslope adiabatic warming, such as Marquette that has
climbed into the mid-upper 80s. Dewpoints staying in the 50s, which
with the temps have kept RH values so far largely in the 40s with
some 30s in the interior west and in the east, have kept the above
normal temperatures bearable.
Overall the pattern doesn`t change much this afternoon and overnight
tonight, so expect temps to warm and dewpoints to fall a few more
degrees before falling as the sun sinks toward the western horizon.
The cutoff low to the west will migrate north into Saskatchewan and
Manitoba tonight while the low over the southeast remains nearly
stationary. This will keep the ridging and dry air over the Upper
Great Lakes while the surface front over the northern Plains shifts
a little more east. Given the persistent southerly flow and warmth
aloft, expect temps to cool off some, but don`t expect overnight
lows to fall to normal values for the time of the year. Overnight
lows by Lake Superior should stay in the low 60s, as well as the
high country of the Keweenaw. In the interior expect lows in the mid
50s and by the Lake Michigan lakeshore lows close to 50.
Thursday, while still stuck between the mid/upper level lows,
ridging will weaken as heights decrease and the approaching cold
front edges closer. By the late afternoon/early evening, precip out
ahead of the frontal feature should have moved into the far western
lake and perhaps into the far western UP. Clouds will gradually fill
in the western skies as the feature approaches, but in the east
expect a mostly clear day. Highs should be similar to today`s, with
interior and southerly downslope prone areas the warmest in the
upper 80s and some isolated areas near 90. Steep low level lapse
rates will promote some deeper mixing to around 4-5k ft. This should
bottom out dewpoints in the low 50s and bring RH values into the
upper 20s in parts of the interior west and 30s elsewhere. The
deeper mixing will promote some gusty winds reaching down to the
surface. Generally speaking, expect around 15-20 mph with some areas
in the western interior and Michigamme Highlands reach 20-25 mph
wind gusts.
.LONG TERM...(Thursday night through Wednesday)
Issued at 359 PM EDT WED JUN 17 2020
The extended starts out with a continued blocking pattern with quasi-
rex block over southern Alberta and Saskatchewan with another cutoff
low over the mid Atlantic / Ohio River Valley. These systems will
move very slowly with the eastern cutoff low tracking up the New
England coast by Tuesday. The low pressure in Canada will make slow
progress into Ontario and be with us for much of next week.
Precipitation chances will come up Friday as a weakening cold front
stalls over the eastern UP. Instability combined with PWAT values of
1.5 inches in the deterministic models and approaching 2 standard
deviations in the NAEFS anomalies could lead to locally heavy
downpours with any thunderstorms that develop. Shear will remain
weak so not expecting organized convection. Some upper level support
with divergence at 300 mb will aid in developing convection.
A series of shortwaves will affect the region Saturday through
Sunday with multiple rounds of precipitation. Increasing low level
moisture will keep fire weather concerns to a minimum through the
weekend.
It looks like a break in the active weather is possible for Tuesday
as the shortwaves move off and the area is under the base of the
upper level trough. Forecast temperatures overnight next week are in
the low 40s over the interior from the blend but could trend cooler.
Models do bring a few more shortwaves into the area by mid week so
possible there will be enough clouds to limit radiational
cooling. At this point went with the blend temperatures but will
need to monitor as we get closer for possible frost.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 726 PM EDT WED JUN 17 2020
VFR conditions will prevail at all terminal sites through the
forecast period. Only hiccup during forecast period is some LLWS
expected at each of the TAF sites overnight with a low-level jet of
30 knots. KIWD LLWS should begin the earliest and last the longest.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 349 PM EDT WED JUN 17 2020
Today and tomorrow, high pressure will keep Lake Superior calm and
under the influence of mainly southerly winds. The exception being
high platforms that tap into winds above the marine layer; these
could see some wind gusts above 20-25 kts;. Another exception are
the NE winds blowing toward Duluth. Weakening cold front approaching
from the west tomorrow afternoon may produce some
showers/thunderstorms in the western portion of the lake by
afternoon. Despite the cold frontal passage Thursday night into
Friday, weak winds are expected with this feature and afterwards
through the weekend.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JP
LONG TERM...JH/NL
AVIATION...TAP/RJT
MARINE...JP
AREA FORECAST DISCUSSION
National Weather Service Morristown TN
933 PM EDT Wed Jun 17 2020
.UPDATE...
EVENING UPDATE.
&&
.DISCUSSION...
Showers generally dissipating across the area as surface cools.
Area of showers approaching Tri-Cities area has been weakening,
and cloud tops are steadily warming, so think that HRRR trend of
fading these showers out, is on track as well. Am trimming back
the POPs in Southwest VA somewhat before 06z, as later periods
were dry enough already. No other changes at this time.
GM
&&
.AVIATION...
00Z TAF DISCUSSION.
Upper low continues sluggish movement over general region. Lower
ceilings over our area now drifting to southwest, with slightly
higher ceilings wrapping into northeastern sections, might try to
slowly erode lower ceilings initially at KTRI, then nighttime
cooling will allow ceilings to lower again. Have some light fog
forecast at KTYS/KTRI--tough to know how thick it will get with
multiple cloud layers above surface, but brief clearing could
allow for thicker fog to form. After sunrise any fog should be
dissipating. Showers/storms possible with best chances during
afternoon heating.
GM
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 62 83 65 88 66 / 10 30 20 30 10
Knoxville McGhee Tyson Airport, TN 59 82 64 85 64 / 10 30 40 50 20
Oak Ridge, TN 58 82 62 85 64 / 10 30 30 40 20
Tri Cities Airport, TN 57 77 59 80 60 / 30 60 40 80 30
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$