Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/23/20
Area Forecast Discussion
National Weather Service La Crosse WI
1030 PM CDT Mon Jun 22 2020
.SHORT TERM...(Tonight)
Issued at 216 PM CDT Mon Jun 22 2020
A slow-moving cold front continues to make gradual southward
progress through the forecast area this afternoon. The front`s
current position is given away by the deformation-driven band of
showers stretching from central Iowa into central Wisconsin.
Additional support is coming from a mid-level shortwave trough
rotating through the region this afternoon. Dewpoints near and south
of the front remain in the low to mid 60s, but behind it they are
rapidly dropping through the 50s. Temperatures across the board have
been kept in check by the overcast skies and ongoing showers across
much of the area, with even reaching 70 a Herculean feat.
Main concern the rest of this afternoon will be whether any
thunderstorms manage to develop to produce heavier rainfall rates.
Realized instability has been much lower than models had originally
shown for today. Latest RAP analysis shows barely a couple hundred
J/kg of CAPE, and find it hard to believe that the atmosphere has
any chance of recovering through the rest of the afternoon,
despite RAP suggesting that will be the case. Better instability
remains to our south, where some convection has managed to
develop. In addition, there really isn`t any moisture transport
focused on the area and warm cloud depths are slowly declining.
So, rainfall rates across our area have been behaving thus far
today, and latest trends suggest this will continue to be the case
through early evening. Will keep Flash Flood Watch for Fayette,
Clayton, and Grant counties going in case any convection sneaks
into that area, which was raked by significant rainfall over the
last 24+ hours. Locally 4+ inches was reported over southeast
Fayette and southern Clayton counties mainly just from last
night. Any heavier rainfall rates over that small area would lead
to quick runoff and possible flash flooding. But again, trends are
suggesting a diminishing flash flood threat.
Rain axis expected to slowly pivot out of our south and east
through the rest of this afternoon and evening as the front pushes
through our area. Could see some partial clearing work in from
the west tonight, but area of stratocu to our northwest will
eventually sag down into our area towards daybreak. Good night to
sleep with windows open as temperatures and dewpoints fall through
the 50s.
.LONG TERM...(Tuesday through Monday)
Issued at 216 PM CDT Mon Jun 22 2020
A cool (and less humid) day is expected on Tuesday as northwest
flow remains present behind the passage of a cold front. Highs on
Tuesday will be in the low to mid 70s with dewpoints in the 50s.
An upper-level low will continue to rotate over Ontario the next
few days, bringing with it chances for widely scattered diurnal
showers/storms on Tuesday and Wednesday as a couple shortwave
troughs ripple through the large-scale flow. A brief break in
precipitation looks likely on Thursday as a short period of upper
ridging moves overhead, resulting in more summerlike temperatures.
Flow becomes more southerly going into Friday, which will pull in
moisture and increased humidity values. An area of low
pressure/cold front then looks to move through the area Friday
into Saturday, bringing shower and storm chances. Although exact
placement and timing of said low is still a little uncertain at
the moment, will need to keep an eye out for possibly a few
stronger storms. Forecast soundings depict plenty of instability
to work with and decent shear, though warmer temperatures aloft
may cap things off. The front looks to stall somewhere over the
Midwest states going into the weekend, keeping southwesterly flow
present and chances for showers/storms possible through the
weekend. High temperatures through the weekend and early next week
look to be in the 80s, with dewpoints in the 60s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1030 PM CDT Mon Jun 22 2020
Cigs: sct-bkn mid vfr deck overnight, with satellite trends
suggesting skies should go mostly bkn by 12z or so (still VFR).
Going to hold with generally a BKN VFR deck through the day, into
the evening...although some periods of SCT seem likely too.
WX/vsby: with recent rains, light sfc wind field, and variable
clouds overnight, could see some fog develop. Meso models suggesting
western WI more likely to see some (mostly shallow?) fog. While
light wind at the sfc, RAP/HRRR bufkit soundings already blowing at
+15kts by 200 ft - not favorable for valley fog development at KLSE.
Going to keep P6SM going for both TAF locations and monitor.
Northwest flow a loft, shortwave energy and daytime instability will
fire off more diurnally driven shra Tue afternoon. Some thunder also
possible. Will go with VCSH for now, revising forecast if/when
impacts to TAF sites become more probable.
Winds: looking to hold northwesterly through the period, mostly
around 10 kts or less daytime but with a few higher gusts Tue
afternoon. Lighter winds overnight ahead of a sfc trough that
doesn`t move in til btwn 09-11z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...Kurz
LONG TERM...NMB
AVIATION...Rieck
Area Forecast Discussion
National Weather Service Birmingham AL
623 PM CDT Mon Jun 22 2020
.UPDATE...
For 00Z Aviation.
&&
.SHORT TERM...
/Updated at 1020 AM CDT Mon Jun 22 2020/
Through this evening.
It`s shaping up to be an active weather day here across Central
Alabama with a fairly potent upper level shortwave moving in from
the west, which will help to trigger numerous showers and storms
this afternoon. First, let`s look at some mesoscale features of
note this morning. Large outflow boundaries are evident on visible
satellite from previous convection that developed in Arkansas and
northwest Mississippi during the overnight hours. That boundary is
already triggering convection across our western and northwest
counties as daytime heating increases. Meanwhile, a secondary
outflow boundary has raced northward from the coast into southern
Mississippi and southwest Alabama, already triggering widespread
convection in those locations. Therefore, in addition to mesoscale
features such as these, the synoptic scale forcing from the
shortwave activity will amplify the shower and thunderstorm
coverage this afternoon. The KBMX 12z modified sounding this
morning indicated a very unstable situation, with over 3800 J/kg
of SBCAPE, and downdraft CAPE over 1000 J/kg. PWATs will be on
the rise as we go through the day with southwesterly surface flow
continuing. RAP surface analysis is indicating PWATs around 1.8
inches across the southwestern counties, and that moisture will
continue moving northward as we go into the afternoon. RAP
analysis is also already indicating 3500 J/kg of SBCAPE across our
southern tier of counties. With the additional upper level
support and 0-6km bulk shear values around 20 knots, we`ve
included the chance for isolated severe storms this afternoon
through the early evening hours. Damaging winds gusts to 60mph and
quarter size hail will be the hazards with the stronger storms.
We`ll have to closely watch the development along these outflow
boundaries today. If organized cold pools can develop behind the
outflow boundaries today, slab-like lifting could occur, which
would then lead to a more organized severe storm threat. In
addition, heavy rainfall with the high PWATs will also give us a
localized flood potential in a few locations if we get any
training thunderstorms. We`ll be watching radar and observation
trends closely as we go through the day.
56/GDG
.LONG TERM...
/Updated at 0327 AM CDT Mon Jun 22 2020/
Tuesday night through Sunday.
An ill-defined front should be located over southern TN or
northern AL Tuesday night with persistent moist west-southwest
flow over the forecast area. This will be supportive of numerous
showers and storms Tuesday night into Wednesday. There is model
disagreement on the potential for subsidence on Thursday with
possibilities ranging from no rain to scattered activity. The
current forecast will side with persistence and feature 30-50
percent POPs.
A general reduction in rain chances appears likely for Friday
through Sunday as a deep-layer ridge builds over the region. The
ridge does not appear particularly impressive, and isolated to
scattered convection may continue to occur each afternoon and
evening.
87/Grantham
&&
.AVIATION...
00Z TAF Discussion.
An active weather pattern will persist thru the period. Monday
afternoon showers and storms have stabilized the air mass across
Alabama and a break in the rain will occur thru 05z. A low level
trof will pass through north Alabama between 09z and 15z.
Widespread showers and embedded tstms will develop over west
Alabama by 08z and spread eastward thru the morning hours. The
most active storms will shift to areas south of I-20 by 17z. The
approaching low level trof will produce isentropic lift and cigs
will lower overnight, with widespread IFR cigs between 10z and
14z, mainly north of KMGM and KTOI. The cigs will rise quickly
after 14z with cigs aoa 5000 feet after 18z.
58/rose
&&
.FIRE WEATHER...
High humidity and rain chances will continue through at least
Wednesday. Showers and thunderstorms could become widespread at
times. Winds should generally be light and from the southwest
through Wednesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 71 85 67 82 66 / 60 80 70 60 40
Anniston 71 85 67 82 66 / 50 80 70 80 50
Birmingham 72 86 70 83 68 / 60 80 70 70 40
Tuscaloosa 72 87 70 83 68 / 60 80 70 80 40
Calera 71 86 69 82 67 / 50 80 70 80 50
Auburn 70 86 68 81 67 / 40 60 70 90 50
Montgomery 71 90 70 84 69 / 30 70 70 90 50
Troy 71 90 70 84 69 / 30 60 60 90 50
&&
.BMX WATCHES/WARNINGS/ADVISORIES/...
None.
&&
$$
Area Forecast Discussion
National Weather Service Cheyenne WY
532 PM MDT Mon Jun 22 2020
.SHORT TERM...(Tonight - Wednesday)
Issued at 213 PM MDT Mon Jun 22 2020
A few showers and thunderstorms are possible through the remainder
of the afternoon into the early evening across southeast Wyoming &
the western Nebraska Panhandle. An unstable air mass associated w/
cyclonic/northwest flow aloft is the main reason for this activity
today. SPC Mesoanalysis only shows around 500 J/kg CAPE across the
region, so strong to severe storms are unlikely. However, a rather
dry boundary layer is in place with inverted-v type profiles. This
may yield gusty winds in excess of 45 MPH with some storms. Fairly
cool again for Tuesday with potential for an isolated thunderstorm
or two, mainly along the Laramie Range. Upper-level ridging should
become more established over the central Rockies on Wednesday with
H7 temperatures returning to +12 to +14 deg C. Highs are likely to
soar back into the upper 80s and low 90s across a large portion of
the area as a result. Minimal chances for precipitation.
.LONG TERM...(Wednesday Night - Monday)
Issued at 240 AM MDT Mon Jun 22 2020
Medium to long range models in reasonable agreement late this week
and into next weekend. Models continue to indicate a slow moving
upper level trough pushing across the northern and central Rocky
Mountain region through Friday, and likely forming a closed low
as it digs southeast across the high plains of Colorado. All
models and ensembles agree that this system will move pretty slow
across the area, so expect unsettled weather late this week. The
most likely day to see some severe weather is Friday, although
Thursday can not be ruled out either due to minor timing
differences with shortwave energy out ahead of the main upper
level trough. Continued to increase POP both Thursday and Friday;
with Friday looking the most favorable for widespread rainfall and
thunderstorms based on the GFS and Canadian models. Temperatures
will trend cooler as a Pacific front moves through the region
Thursday night and Friday with daytime highs only in the 70s
along/west of I-25, and mid 70s to low 80s further east across
western Nebraska.
For next weekend, model solutions diverge a bit with the movement
of the upper level trough/low, with the GFS and Canadian keeping
shower activity and thunderstorms near the Colorado border and
I-80 corridor through most of the day on Saturday. Temperatures
should return to above normal levels as all models show a return
to southwest flow aloft. However, another strong Pacific system
will be moving onshore and towards Wyoming later on Sunday, which
may bring another prolonged period of unsettled weather for the
last few days of the month.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 523 PM MDT Mon Jun 22 2020
Latest high res guidance has removed initial chances of showers
from KCYS into the NE Panhandle. Retained the shower possibility
for KLAR and KRWL based on HRRR and NAMNEST through about 03-04z.
Otherwise winds expected to diminish after sunset with diurnal
increase in morning. Some shower activity possible Tuesday
afternoon though confidence on direct impacts low at this time
though inclusion in later issuances likely. VFR conditions to
persist.
&&
.FIRE WEATHER...
Issued at 220 AM MDT Mon Jun 22 2020
Fire weather conditions look to be slightly elevated the next
couple of days as conditions across the area begin to dry out due
to warmer temperatures, and dry thunderstorm activity increases.
Gusty, erratic winds are possible near thunderstorms that develop,
but RH values do not approach 15-20% until Wednesday afternoon
after daytime maximums occur.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...CLH
LONG TERM...TJT
AVIATION...WM
FIRE WEATHER...BW
Area Forecast Discussion
National Weather Service Dodge City KS
614 PM CDT Mon Jun 22 2020
...Updated Aviation Discussion...
.SHORT TERM...(This afternoon through Tuesday night)
Issued at 1217 PM CDT Mon Jun 22 2020
NW flow aloft is firmly established over SW KS at midday, with
passing mid and high clouds. Yesterday`s impressive MCS wiped out
most of the CAPE/moisture/instability out of SW KS, but not all
of it. Mesoanalysis is still holding onto MUCAPE of 2000 J/kg
across the SW zones. Insolation is working on this airmass, and
satellite imagery shows an outflow boundary in the vicinity of LBL
that may serve as a convective initiation focus this
afternoon/evening. Thunderstorms will develop near the Raton Mesa/
I-25 corridor early this afternoon. HRRR (which has performed
very well the past 2 days and running) shows consistency with
these initial supercells quickly congealing into a squall line,
oriented from near Elkhart to west of Amarillo by 7 pm. Clearly,
the vast majority of the squall line and the associated risk for
strong/ damaging winds will remain in the Panhandles/West Texas
through this evening. Uncertainty surrounds how much of this
activity can sneak across the Oklahoma border into Kansas.
Continued to carry chance to likely pops along the immediate
Oklahoma border this evening/tonight. Am confident some convection
will make it into Kansas, but severity is unclear. For now, 5%
wind/hail probability from SPC for the southern zones is
warranted. Otherwise, dry weather will prevail elsewhere tonight,
with a mix of mid/high clouds, and winds trending light and
variable in a weak pressure gradient. Expecting upper 50s and
lower 60s sunrise Tuesday.
NWly flow aloft will be maintained Tuesday, in response to a
sprawling 593 dm upper high centered over Arizona. This time of
year, NW flow aloft will encourage a chance of thunderstorms
virtually on a daily afternoon/evening basis, as moisture and
instability are present, and various vorticity maxima/shortwaves
arrive from the NW. 12z NAM, extended HRRR, and ECMWF all have
convective QPF over primarily the west/NW zones Tuesday
afternoon/evening, in this continued NW flow environment. 12z NAM
maintains 2000 J/kg CAPE and sufficient shear to support vigorous
updrafts. Slight chance/chance category pops are clearly warranted,
with at least a marginal hail/wind risk. Afternoon highs in the 80s,
with winds trending light upslope E/SEly Tuesday.
.LONG TERM...(Wednesday through Monday)
Issued at 202 PM CDT Mon Jun 22 2020
A typical early summer regime is expected for SW Kansas, as
varying degrees of NWly mid level flow will continue through at
least Friday. As such, there will be daily rounds of mainly late
afternoon/nocturnal scattered thunderstorms Wednesday through
Friday. It will not rain for three days, and it will not rain
everywhere. Rather, pops in the 20-40% coverage range are
warranted daily during the preferred convective maximum time each
diurnal cycle. Convection will either be directed to SW KS from
the mountains (mainly nocturnal), or various small vorticity
maxima/shortwaves will interact with the continuous late June
moisture/instability supply. Bouyancy will be available each day,
and with NWly flow at 500 mb, shear will remain sufficient for
some convective organization each day. 12z MEX pops Wednesday
through Friday are in near climatology, 25-30% each day, and this
trend was retained in the NBM grids. The new 12z ECMWF supports
scattered thunderstorms Wednesday PM, and a mesoscale convective
complex genesis region across the southern zones late Friday. No
obvious organized severe weather episodes are apparent with the
models, but this is the time of the year where we have to be on
guard for the occasional NWly flow surprise (mesoscale accidents).
Temperature forecast is much simpler, very near normal, with
afternoon highs in the upper 80s and lower 90s each day.
12z ECMWF shows NWly flow aloft ending over the weekend, as the
strong upper high over the SW weakens dramatically, reacting to
an unseasonably strong trough digging into the Pacific NW.
If ECMWF trends are correct, high pressure would relocate over
NE U.S. by Monday, forcing SWly flow aloft and dryline/lee trough
maintenance across the plains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 607 PM CDT Mon Jun 22 2020
Northeasterly winds will be at less than 10 knots overnight. A
brief period of low VFR ceilings will be possible near and south
of Garden City and Dodge City between 02z and 09z Tuesday. Also
there may be a few widely scattered thunderstorms near the
Oklahoma border that might impact the Liberal area between 02z and
04z Tuesday. MVFR ceilings will be possible in and near these
thunderstorms. The northeast to easterly wind early Tuesday
morning at 10 knots or less will veer to the southeast Tuesday
afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 61 84 63 89 / 20 10 20 30
GCK 60 85 61 90 / 20 20 20 10
EHA 61 83 62 89 / 70 40 30 10
LBL 61 85 63 89 / 60 30 20 10
HYS 59 84 61 88 / 10 10 30 40
P28 64 86 64 89 / 10 10 10 20
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Turner
LONG TERM...Turner
AVIATION...Burgert
Area Forecast Discussion
National Weather Service Grand Forks ND
1024 PM CDT Mon Jun 22 2020
.UPDATE...
Issued at 1020 PM CDT Mon Jun 22 2020
A few sprinkles/light showers are lingering over northwest MN, but
overall activity is following expected trends and should end over
the next few hours. More expansive cloud cover is transition
south with a decreasing trend from the north. I made further
adjustments to account for these trends, otherwise forecast is on
track with quiet weather the rest of the night.
UPDATE Issued at 641 PM CDT Mon Jun
22 2020
CU field and isolated showers associated with cold pool aloft
still lingering early this evening should dissipate with loss of
daytime heating/favorable low level lapse rates. Still can`t
completely rule out "cold air" funnels before sunset with high
vorticity environment and good low level lapse rates. Not an
expected impact if there are any funnels as stretching potential
is minimal to non existent in current RAP analysis and without
surface convergence in absence of well defined surface boundaries
I am less confidence in non-supercell tornado potential. Fine
tuned coverage/timing of cloud cover and near term temp trends
otherwise forecast is on track.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 222 PM CDT Mon Jun 22 2020
Fairly low impact weather throughout the short term.
The thick cumulus and isolated showers will diminish by early
evening, although some cloud cover will likely linger overnight.
Areas that managed to clear out last night dipped into the lower
40s for lows. At this point, expect a bit more cloud cover, so
think lows will be higher than that. Tuesday looks like a very
similar day to today (and this past Sunday). One difference is
that 500mb temperatures are expected to be a few degrees colder.
Therefore the idea of showers and isolated thunder still looks
good. Any of this activity would also fade away pretty quickly in
the evening.
.LONG TERM...(Wednesday through Monday)
Issued at 222 PM CDT Mon Jun 22 2020
The period starts on the quiet side as the upper level ridge shifts
over the region. Surface high pressure retreats into the central
Plains. Return flow is light in a weak pressure gradient ahead of
the next system developing over the High Plains.
For Thursday into Thursday night...a vigorous short wave crosses the
area. Combined with abundant low level moisture and surface
trof...there is a potential for stronger thunderstorms although a
discrete severe storm cannot be ruled out.
By Friday...the pattern becomes a bit more unsettled as a series of
upper level waves propagate through the flow...creating instability
and providing more chances for showers and storms through the rest
of the period. Temperatures will be near to above normal to end the
period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 641 PM CDT Mon Jun 22 2020
Cu field and isolated showers producing prevailing ceilings
3500-6000 kft AGL across eastern ND and northwest MN should
lift or dissipate around sunset this evening. Models indicate
Axis of moisture over west central MN that result in MVFR
ceilings developing 10-13Z Tuesday, but guidance that shows this
keeps it south of KTVF/KBJI and I didn`t include mention. CU field
in the 3500-6000 kft AGL range redevelops by late Tuesday morning,
and once again lingerings through sunset with a few showers across
the afternoon showers (maybe isolated thunder). Pattern supports
prevailing winds out of the northwest generally 7-11kt during the
daytime periods, decreasing at night.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$
UPDATE...DJR
SHORT TERM...Godon
LONG TERM...Hopkins
AVIATION...DJR
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
655 PM CDT Mon Jun 22 2020
.SHORT TERM...(This evening through Tuesday Night)
Issued at 425 PM CDT Mon Jun 22 2020
Upper air and water vapor analysis shows NW flow in place across
the Central Plains around an upper trough over S Canada. An MCV
can be seen rotating thru E IA, with a couple weaker vort lobes
seen on WV over the Dakotas. Tstms have blossomed over north
central and northeast Neb. early this afternoon, out ahead of the
SD vort lobe and associated cold front. 12Z LBF and OAX ROABs
indicated relatively cool convective Ts, given seasonably cool mid
level temps of only 3-5C H7 temps. 3PM obs feature temps generally
in the 80s and dew points in the upper 50s to low 60s.
For this afternoon and evening...forecast reasoning remains
largely unchanged from earlier today. SPC mesoanalysis places
1000-1500 J/kg of MLCAPE amidst effective deep layer shear
magnitudes of only 25-30kt. This is keeping convection rather
disorganized and pulsey per latest composite radar loop. However,
this may be just enough CAPE/shear along with aforementioned cool
mid level temps and associated seasonably low wet bulb 0C heights
could promote some marginally severe hail. Calls to folks beneath
the stronger cores we`ve had so far have yielded no ground truth
reports thus far. Steep low level lapse rates of 8-8.5 C/km and
DCAPE values around 1000 J/kg may also promote some bouts of gusty
winds around 60mph. As far as coverage, looks like the NE half of
CWA (NE of Kearney-Beloit) will have best chcs/scat coverage
given favorable positioning w/in left exit region of seasonably
strong H3 jet streak (60-70kt) and ahead of advancing vort lobe.
All in all, a pretty straightforward setup in which any severe
tstms will be marginal and isolated. Expect a distinct diurnal
decr to convection, so any limited svr threat should end by 8pm.
The rest of the overnight looks to be fairly quiet w/ clearing
skies, at least for a few hrs, after sunset. One item to watch
will be potential for weak mid level convection over mainly south
central NE after 09Z. Latest RAP runs, and to some extent 18Z
HRRR and 12Z NAMNest, indicate a small zone of ascent within
H85-H7 layer, associated w/ some isentropic ascent seen best on
300K sfc, and ahead of fast moving vort lobe w/in seasonably fast
cyclonic/NW upper flow. These types of waves are notoriously
difficult to pin down, but could envision a few high-based returns
around dawn tmrw morning. Have introduced some "sprinkles" for Tue
AM, but may need some outright shwr mention if trends continue.
Have introduced a slgt chc for tstms for Tue aftn as low level
lapse rates steepen and cool mid level temps remain. SREF and
12Z/18Z HRRR have hinted at this and this is backed by NAM
forecast soundings showing a few hundred J/kg of SBCAPE for the
aftn hrs. Otherwise, should be a seasonably pleasant day w/ highs
in the upper 70s N/NE to mid 80s far SW along w/ lgt winds.
Weak low level WAA and H85 convergence may keep a low end chc for
convection going across the far SW Tue night. NAMNest and SREF
probs highlight north central KS w/ best potential, w/ even better
potential likely a bit further S closer to deeper moisture plume.
.LONG TERM...(Wednesday through Monday)
Issued at 425 PM CDT Mon Jun 22 2020
Zonal to NW flow continues thru the end of the work week before
potentially turning more zonal to SWrly for the upcoming weekend.
After a brief dip in temps on Tue, expect a gradual warming trend
for late week and into the weekend.
The shortwave ridge axis that creeps into the area Tue night will
continue to shift to the E on Wed. This will bring some return
flow/WAA into at least KS portions of the CWA by late aftn, and
perhaps south central Neb as well. There`s decent model consensus
in a plume of moderate instability/shear by Wed aftn co-located
w/ diffuse NW to SE draped warm front. Continued cyclonic upper
flow almost guarantees that there will be at least one or two
upper perturbations rotating thru, providing at least weak upper
level support/ascent. Directional shear will not be lacking given
S/SE flow at the sfc near the front veering sharply to NWrly at
H7, resulting in 35-45kt+ of effective shear. Thus, IF some
storms can develop, the CAPE/shear space would be supportive of
supercells, but its just too early to resolve finer scale details
that would be important to tstm coverage and placement, so think
the SPC Day 3 "Marginal" over the S is a good place to start, for
now.
Rising heights during the day Thu should lead to mainly dry
conditions and warming temps to around 90F. The next trough
passage is forecast to arrive Thu night into Fri, though models
disagree on the timing and amplitude. Too early for specifics, but
EPS 24hr precip plots would suggest some active wx in the Thu
night to Sat AM time frame.
Thereafter, general pattern evolution suggests continued warming
trend and low end tstm chcs w/ possible transition to SW upper
flow. Models agree that the mean upper trough position should be
well W of the area over N Rockies and/or Pac NW, but differ w/r/t
finer details/low amplitude disturbances. 12Z data, in particular
the EPS, has trended towards a little more ridging/drier for the
weekend, but would like to see more consistency before believing
this trend w/ much confidence.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 652 PM CDT Mon Jun 22 2020
Significant wx: Scattered tstms w/ gusty winds next couple of hrs
Tonight: The main issue will be scattered tstms rolling through
next 1-2.5 hrs or so. Could see some gusty NW winds 25-30kt with
the arrival of this activity but bases have been primarily above
MVFR levels thus far, so kept the TAFs VFR. Expect decr clds/pcpn
03-04Z, with mainly clr skies returning around midnight.
Confidence: general trend - high, winds - medium.
Tue: VFR. Some clds w/ bases 5-6K ft may return around sunrise and
will need to watch this for iso shwrs. TAFs remain quiet, for now,
in the morning, but inserted some VCTS for potential of iso pop-up
t-showers in the aftn. Winds will start off light out of the NW
then incr a bit for the aftn, sustained around 10kt w/ gusts near
20kt. Confidence: Medium.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...Thies
LONG TERM...Thies
AVIATION...Thies
Area Forecast Discussion
National Weather Service Goodland KS
950 PM MDT Mon Jun 22 2020
.SHORT TERM...(This evening through Tuesday)
Issued at 245 PM MDT Mon Jun 22 2020
Overview: NW to NNW flow aloft will prevail through mid-week --
on the eastern periphery of an upper level ridge over the Desert
Southwest/Intermountain West, and the southwest periphery of a
cut-off (or nearly cut-off) upper low over the Great Lakes.
This Afternoon/Evening: Though little/if any low-level forcing is
present this afternoon -- differential heating, weak (10-15 kt)
upslope flow (Southeast CO), marginal diurnal destabilization
[~500 J/kg mlcape] along/south of I-70 (Eastern CO), a relatively
weak cap [7.0-7.5 C/km H7-H5 LR], and weak DPVA attendant a small
amplitude wave progressing from CO into Southwest KS via NW flow
aloft (per 19Z SPC Mesoanalysis H7-H4 DPVA) -- have all
contributed to the development of isolated convection along the
southern flank of the Palmer Divide (invof Hwy 94 between Colorado
Springs and Eads). With the marginally unstable/uncapped airmass
largely confined to Southeast CO, the presence of a N-S DCAPE
gradient (increasing values with southern extent), mean steering
flow from the WNW, and deviant /right-mover/ motion from the NNW,
convection developing on the southern flank of the Palmer Divide
this afternoon will tend to propagate toward the SE-SSE. With the
above in mind, convection is largely anticipated to remain outside
of the NWS Goodland CWA -- aside from an updraft or two that may
briefly graze southwest portions of Cheyenne county, CO and
(possibly) southwest portions of Greeley county, KS. Severe
weather is not anticipated.
Tonight: Moisture return, an increasingly upslope component to
low-level flow (as flow veers to the E), and [possibly] small
amplitude perturbations in NW flow aloft may aid in the
development of isold/sct nocturnal convection in Eastern CO and
portions of Western KS. Simulated reflectivity forecasts via the
18Z HRRR support such a scenario in the 05-11Z time-frame, though
the 18Z NAM NEST is less enthusiastic. Confidence is low with
regard to whether or not convection will develop.. and, if so..
whether or not coverage will be isold/sct. At this time, the
relative best potential for convection appears to be along/west of
Hwy 27. Severe weather is not anticipated.
Tue-Tue night: Marginal diurnal destabilization (500-1000 J/kg
mlcape), weak low-level upslope flow on the eastern periphery of a
broad lee sfc trough, and small amplitude perturbations in NW
flow aloft may aid in the development of convection in the
southern flank of the Palmer Divide (south and west of Goodland)
early Tuesday afternoon -- though coverage/intensity may highly
depend upon (1) the presence and (2) precise timing of any small
amplitude perturbations -- upstream features that can be difficult
to discern a few hours out, let alone 24 hours out. With this in
mind, a fair amount of uncertainty persists with regard to
specifics. Isolated marginally severe storms are possible (south
and west of Goodland) in the 19-01Z time frame. Some potential for
nocturnal convection may also persist Tue night.
Wed-Wed night: Flow aloft is anticipated to veer from the NW to
the NNW, on the eastern periphery of the upper ridge building
slowly eastward into the Rockies. Guidance suggests that southerly
return flow may be somewhat more pronounced Wed -- as the MSLP
gradient tightens on the eastern periphery of a broad lee cyclone.
Given a potential for nocturnal convection Tue night/Wed morning,
and considerable uncertainty with regard to any upstream features
(i.e. small amplitude waves/perturbations in NNW flow aloft) --
the convective forecast in this period remains very uncertain.
.LONG TERM...(Thursday through Monday)
Issued at 220 PM MDT Mon Jun 22 2020
For the extended period, the models start out showing an upper air
ridge over the Plains that will progress eastward into the Eastern
US by the weekend. At the same time, they are showing an upper level
low developing over CO. As this ridge progresses eastward, a few
shortwave troughs will move through the area. In the beginning of
the next week, an upper level low travels in from PACNORWEST placing
the local area between a trough and ridge pattern. Intensity and
placement of the low varies between models so this will be monitored.
On the surface, a chance of showers and thunderstorms are expected
later Thursday due to a localized low associated with an upper
shortwave trough passing over the area. Later, a cold front
associated with another upper level shortwave trough will begin to
progress through the area late Friday. A chance of showers and
thunderstorms could be expected with this front through Saturday.
After the front passes, dry conditions returns to the area; however,
isolated showers and thunderstorms can not be ruled out. Fire
weather is possible for the western counties of the CWA as RH values
begin to drop Sunday into Monday with wind gusts forecasted up to 25
mph at this time by the models.
Thursday high temps for the CWA are expected to be in the middle 90s
followed by the upper 80s to lower 90s on Friday and Saturday due to
the precipitation cooling things in the area. Sunday and Monday
should see a return of highs reaching the middle to upper 90s across
the CWA. Overnight Lows are forecasted to drop into the middle 50s
to lower 60 range over the western counties of CWA with the eastern
counties dropping into the lower to middle 60s range.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 950 PM MDT Mon Jun 22 2020
For KGLD and KMCK, vfr conditions expected through the period. The
forecast area remains under northwest flow aloft and latest model
solutions are bringing an increase in clouds centered around
7000-10000 ft overnight then a mostly sunny to partly sunny sky
with cumulus clouds during the afternoon. There could be a few
sprinkles or light rain showers near the KGLD terminal in the
09z-16z timeframe. Any afternoon/evening convection at this time
appears to be far enough away from the KGLD terminal to not
include in the forecast. Winds generally variable 6kts or less
from taf issuance through about 22z then establish an northeast to
southeast direction at speeds around 6-7kts.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...VINCENT
LONG TERM...99
AVIATION...99
Area Forecast Discussion
National Weather Service Grand Rapids MI
740 PM EDT Mon Jun 22 2020
LATEST UPDATE...
Aviation
.SYNOPSIS...
Issued at 330 PM EDT Mon Jun 22 2020
-Showers and thunderstorms tonight into early Tuesday
-Beach hazards Tuesday, cooler
-Still cooler with isolated showers and storms Wed-Thur
-Stormy Friday into Saturday
&&
.DISCUSSION...(This evening through next Monday)
Issued at 330 PM EDT Mon Jun 22 2020
-- Showers and thunderstorms tonight into early Tuesday --
Things could turn active for a while late this afternoon and
evening as the approaching mid level trough interacts with
building instability. A few strong to perhaps locally severe
storms are possible through about 10 pm. The main threat is for
gusty winds although some hail is possible too, with the highest
risk for a few svr cells south and southwest of GRR. This is where
RAP MLCape rises above 1000 J/KG over the next few hours. The
storms coming out of Chicago will be ones to watch, as well as new
cells forming along convergent zone near/east of Hwy 131.
After the diurnally enhanced convection fades later this evening
and any svr threat diminishes, the next thing to watch for
overnight into early Tuesday is a heavy rain threat. This would be
mid level deformation zone related as the main wave approaches
and a sfc low deepens overnight into Tuesday morning. The ECMWF
continues to suggest an area of heavy rain impacting srn Lwr MI,
with localized amounts in excess of two inches not out of the
question.
-- Beach hazards Tuesday, cooler --
Deepening sfc low early Tuesday in the vicinity of srn Lk Huron,
and cold advection on the back side of the departing wave,
creates a period of stronger northwest winds and 3-5 ft waves.
Main impacts will be at beaches south of Muskegon and on north
sides of piers, with emphasis on Holland State Park and North
Beach in South Haven. High temps struggling to reach 75 Tuesday.
-- Still cooler with isolated showers and storms Wed-Thur --
Upper level trough will be parked over the region for mid week
which results in slightly cooler than normal highs in the mid to
upper 70s. The cold air aloft may help fuel a few showers and
storms, especially during peak heating and inland from Lk MI.
-- Stormy Friday into Saturday --
Guidance continues to show a pacific system sending a warm front
into the region on Friday, followed by the cold front on
Saturday. A few rounds of showers and storms appear likely during
this time, some containing heavy rainfall and perhaps some
stronger storms.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 735 PM EDT Mon Jun 22 2020
Radar and forecast trends support scattered to numerous showers
and thunderstorms around the TAF sites this evening possibly
through midnight. Local impacts are expected...especially for KAZO
to KBTL and KJXN. Then low level moisture remains high through
the night and into Tuesday morning with IFR and lower conditions
possible from the ceilings. A cold front cuts through the TAF
sites from west to east during the afternoon. This could trigger a
few showers storms...especially the further inland the front
goes. The winds will shift to the northwest and become gusty
behind the departing cold front.
&&
.MARINE...
Issued at 330 PM EDT Mon Jun 22 2020
Deepening low pressure over the ern GrtLks Rgn late tonight and
Tuesday will result in a period of hazardous winds and waves.
Small craft advisories and Beach Hazards are in effect. Northwest
winds of 15 to 25 kts and waves of 3-5 ft expected, highest waves
south of MKG.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement from Tuesday morning through Tuesday
afternoon for MIZ056-064-071.
LM...Small Craft Advisory from 4 AM to 11 AM EDT Tuesday for
LMZ847>849.
Small Craft Advisory from 8 AM to 5 PM EDT Tuesday for
LMZ844>846.
&&
$$
SYNOPSIS...Meade
DISCUSSION...Meade
AVIATION...MJS
MARINE...Meade
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
932 PM EDT Mon Jun 22 2020
.SYNOPSIS...
Showers and thunderstorms are expected tonight into Tuesday as
a cold front moves through the Ohio Valley. A slightly cooler
airmass will move in behind the front with seasonable
temperatures expected through mid week.
&&
.NEAR TERM /THROUGH TUESDAY/...
A weak boundary is lifting up across eastern Indiana and
northern Kentucky and isolated to scattered showers and
thunderstorms have developed along it . This will continue to
lift northeast across our southwest areas through evening but
with some mid level ridging aloft, it is moving into a less
favorable environment. Will therefore just hang on to some
slight chance pops early to account for this.
Otherwise, a broader upper level trough will continue to shift
east across the Mississippi Valley with a series of mid level
short waves rotating through the trough overnight. This will be
accompanied by a strengthening 30-40 knot low level jet that
will shift up into our area through tonight. As a result,
expect fairly widespread showers and embedded thunderstorms
to overspread our area from the southwest/west as we head
through tonight. Not expecting severe thunderstorms though gusts
could reach 30 mph according to HRRR wind gusts and upstream
observations. PWs will push up into the 1.75 to 2 inch range
through the night so once again some locally heavy rainfall will
be possible. Lows tonight will generally be in the upper 60s.
&&
.SHORT TERM /TUESDAY NIGHT/...
The upper level trough will continue to shift slowly east
across the Great Lake and Ohio Valley region Tuesday into
Tuesday night. Some additional mid level energy will rotate
through the trough during the day on Tuesday as an associated
cold front moves slowly southeast across our area through the
day. Expect fairly widespread showers and embedded
thunderstorms to persist through Tuesday morning before
beginning to see a decreasing trend from the northwest Tuesday
afternoon into early evening as the cold front moves through. As
the trough and some better winds aloft develop, the deep level
shear is forecast to increase through the day on Tuesday.
However, with the pcpn mainly moving through during a less
favorable time of day, any severe threat should remain limited.
Highs on Tuesday will be in the upper 70s to lower 80s. Lows
Tuesday night will be in the upper 50s.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
The start of the long term period will be characterized by broad
troughing/cyclonic flow positioned across the Ohio Valley/Great
Lakes regions as a relatively deep mid-level closed low meanders
north of the local area Wednesday through Thursday
Embedded within this broad cyclonic flow aloft will be several
subtle disturbances/vort maxes pivoting around the base of the
longwave trof axis, which will provide enough lift to generate
periodic diurnally-driven/enhanced isolated to scattered
showers/storms both Wednesday and Thursday, especially near the I-70
corridor. This will occur in an environment with seasonably steep
low level lapse rates, enough to generate about 1000j/kg of SB-
instby across central and northern parts of the local area on
Wednesday and upwards of 1200-1500 j/kg SBCAPE again on Thursday.
With the aforementioned broad cyclonic flow, expect the profile to
be one characterized by unidirectional /but seasonably modest/
mid/upper level flow. The main limiting factor to more widespread
activity (i.e. likely PoPs) will be the relatively dry air
entrenched across the area through the column. Have kept PoPs in the
chance category for now on both days, but think Thursday`s activity
may be focused a bit more east than will be the case on Wednesday --
owing to a midlevel impulse ejecting east across the region early
Thursday and serving as a focus for development.
Afternoon/evening shower/isolated storm activity will wane Thursday
evening, marking the beginning of a fairly abrupt pattern change as
we progress into Friday. Model guidance remains in good agreement
showing midlevel ridging expanding north into the Ohio Valley on
Friday, with indications for a warm front to move through the area
during this time frame. This will usher in very warm and moist air
by Friday night in from the west/southwest, with the NNW to SSE
oriented front pivoting east through the Ohio Valley Friday evening.
It is at this point where model guidance begins to diverge a bit on
how specifically the pattern evolves from here. While some global
guidance shows a ridge building quickly into the area, others show
more of a quasi-zonal flow pattern setting up for the weekend, with
modest midlevel flow setting up coincident with an increasingly
unstable low level environment. There are certainly a few solutions
out there that have shown a pattern resembling that of a ridge-rider
environment setting up across the Ohio Valley for this weekend into
early next week with several midlevel impulses ejecting quickly east
on the northern fringe of the developing ridge. This is far from set
in stone, but certainly there is the potential for episodic rounds
of showers/storms progressing east/southeast/south through at least
a portion of the local area during this time frame -- should all of
the necessary ingredients come together in such a manner. At this
juncture, it would be imprudent to speculate on which areas will see
pcpn/storms at what times, since the environments will almost
certainly become more mesoscale-dependent/driven, something that
cannot be modeled with any sort of accuracy at these time ranges.
For now, we will leave it as a warm and moist airmass settling into
the region with increased chances for widespread showers/storms
Saturday through the remainder of the long term period. Highs will
generally be in the 80s to around 90 degrees with lows in the 60s to
around 70 degrees.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Aviation weather will be affected by increasing moisture and
instability ahead of low pressure advancing to the Great Lakes.
Aided by a 35 knot 850mb flow, showers and thunderstorms are
forecast to develop tonight. Thunderstorms may not directly
impact airports so went with VCTS early tonight. Showers may
impact all sites later tonight while instability decreases.
MVFR ceilings are forecast at all sites by Tuesday morning as
the boundary layer moistens to near saturation. Sites should see
improvement back to VFR Tuesday afternoon as the low tracks to
the Central Great Lakes allowing drier air to work in, while
winds shift from south to west with speeds rising over 10 knots.
OUTLOOK...No significant weather expected.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...JGL
NEAR TERM...Coniglio/JGL
SHORT TERM...JGL
LONG TERM...KC
AVIATION...Coniglio
Area Forecast Discussion
National Weather Service Marquette MI
754 PM EDT Mon Jun 22 2020
.SHORT TERM...(This evening through Tuesday)
Issued at 355 PM EDT MON JUN 22 2020
Generally cloudy day across Upper Michigan as a few lake breeze
boundaries can be seen on radar with a few pop-up blips on MQT radar
across Marquette and eastern UP. A nearly stationary front can be
seen on along the trough over west-central UP on the RAP analysis as
this will be the focus for add`l rain development this evening into
tonight. Model run after model run has trended drier and slower
since last night and this forecast resembles that. There is some
add`l development on the last few radar scans across Dickinson,
Florence, and Forest counties along the convergence zone, and expect
this to slowly build over the next few hours.
Tonight, as a developing low pressure system lifts north from WI
along a shortwave trough, the add`l rain will develop along the axis
with the front draped along it. Lowered QPF some from the going
fcst based on latest trends and upstream observations as well. With
plenty of clouds around tonight, felt fine going with median for the
lows with upper 40s across the west and low 50s in the east.
By tomorrow morning, this shortwave trough becomes slightly
negatively tilted as the low deepens slightly with pressure falls
helping increase the winds. Could see some enhancement for the rain
across far eastern Upper Michigan early tomorrow morning with the
add`l lift from the pressure falls. Otherwise tomorrow will feel a
little chilly with stronger winds around 20mph from the NW off Lake
Superior. With some sunshine and scattering skies across the west,
should see temps in the 60s, with temps near 60 across the east.
Along the PRNL, downwind of Lake Superior, temps may struggle to
break the 60 degree mark with persistent NW winds off Lake Superior.
.LONG TERM...(Tuesday night through Monday)
Issued at 340 PM EDT MON JUN 22 2020
Slow moving pattern continues for the start of the extended with a
quasi-rex block in place over Ontario shifting east to Quebec by
Friday. Thereafter, upper level ridging begins to take place over
the upper midwest as another trough digs into the Pacific Northwest.
Ensemble solutions seem to be in agreement with the negative height
anomalies diminishing by the end of the week and positive height
anomalies building and continuing for several days. Models have
tightened up on the timing of shortwaves through the week with
Thursday looking dry in most of the guidance as a shortwave ridge
moves through. The better chance for precipitation arrives late in
the week and early next weekend with a stronger shortwave progged to
move though the region.
For Tuesday night into Wednesday, a low just east of Lake Superior
will be lifting into Ontario and towards northern Quebec. This low
will bring some showers along the eastern U.P. Tuesday night. As
this low moves into Quebec and a surface high pressure ridge begins
to take its place, expect showers to move east, and for partly
cloudy skies to become dominant. There may be a small chance at some
showers and thunderstorms Wednesday afternoon in the south as
diurnal heating may bring in instability to produce convection. As
the surface ridge builds in, expect warmer air to be advected over
the U.P.
The building ridge next weekend could mark the beginning of a
several day period of muggy conditions for the U.P with low level
moisture from the Gulf of Mexico transported into the region on
southerly flow. Deterministic models are handling the ridge
differently with the GFS showing more of an omega block up over the
Hudson Bay with southwesterly flow and shortwaves keeping the
weather active. The ECMWF is much broader with the ridge showing
large scale subsidence keeping the region dry late in the weekend
into early next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 752 PM EDT MON JUN 22 2020
Low pres lifting ne into the Great Lakes will generate shra across
eastern Upper MI tonight into Tue. These shra should remain mostly e
of KSAW. Otherwise, expect VFR conditions tonight at KIWD/KCMX/KSAW.
A trof dropping s across the area Tue morning should be followed by
a period of lower clouds. All terminals should see a period of MVFR
cigs in the morning, especially at KSAW. Not out of the question
that cigs at KSAW could fall to IFR for a couple of hrs. These lower
clouds will then scatter out or lift, resulting in improvement to
VFR at all terminals late morning into the mid aftn.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 355 PM EDT MON JUN 22 2020
There may be some patchy dense fog across the eastern half of the
lake as light rain showers slowly work in tonight. As an area of low
pressure develops and lifts over the lake tonight, NW winds will
gust up to about 25 knots tomorrow...with a few gusts to 30 knots at
the higher observation platforms. Otherwise after Tuesday night,
winds will remain blo 20 knots for the rest of the fcst period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JAW
LONG TERM...NL
AVIATION...Rolfson
MARINE...JAW
Area Forecast Discussion...UPDATE
National Weather Service Portland OR
846 PM PDT Mon Jun 22 2020
Updated aviation discussion
.SYNOPSIS...Sunny and warm weather prevails this afternoon throughout
the forecast area, with mainly clear skies expected to persist
through Tuesday morning. High clouds will gradually increase Tuesday,
but temperatures will remain well above normal. A weak cold front is
expected to move through the Pac NW Tuesday night and Wednesday,
resulting in more clouds, cooler temperatures, and perhaps some areas
of drizzle. High pressure brings a return to warm and dry weather
Thursday and Friday, but it appears likely that cool and unsettled
weather will return for the weekend.
&&
.SHORT TERM...This afternoon through Thursday...High pressure
dominates the weather across the Pacific Northwest this afternoon,
bringing clear skies and above normal temperatures. Hot weather
across northern California and SW Oregon is inducing a thermal trough
of low pressure over those areas, turning low-level flow more
northerly across our forecast area. The offshore component to the
wind is resulting in much drier conditions than the last couple days,
with hardly a cloud in the sky across SW Washington and the entire
state of Oregon. Meanwhile the air mass aloft has warmed considerably
as a transitory ridge of high pressure slides across the region.
Temperatures at 850 mb have warmed from +8 deg C as of yesterday`s
00z KSLE sounding to around +17 deg C at KSLE per the latest RAP
analysis. As a result, temperatures are climbing above 80 deg F this
afternoon for the inland valleys, and above 70 deg F for the coastal
communities.
Very dry air above the surface should lead to clear skies tonight,
save perhaps a few narrow coastal valleys where patchy fog will be
possible tonight/Tue morning. Otherwise, Tuesday will start off sunny
with temperatures a few degrees warmer to start than they were this
morning. With models continuing to show 850 mb temps up around +18 to
+19 deg C over the Willamette Valley 21z Tuesday, it is very possible
that a handful of inland valley locations could break 90 degrees for
high temps Tue afternoon. Coastal areas will be much cooler than
their inland counterparts due to the lack of offshore flow, likely
allowing a fairly early but shallow sea breeze into the coastal
valleys. The weak and shallow onshore flow may cause dewpoints to
come up slightly Tuesday, making it feel a little more humid in
addition to the warmer temperatures. High clouds are expected to
increase through the day Tuesday, but will probably not be
thick/opaque enough to have much of an impact on temps.
Changes come in the form of a weak cold front which will move across
western WA/OR Tuesday night/early Wednesday. After a mild night Tue
night, onshore flow will increase considerably Wednesday for more
clouds and cooler temps. The marine layer will deepen in response to
this system, and could become deep enough for areas of drizzle or
isolated showers Wednesday especially in the higher terrain. The
marine layer will linger through Thu morning, but the marine layer
will become shallower as upper level ridging builds back into the
region. This should allow temps to reach the lower to middle 80s
Thursday afternoon despite the morning clouds.Weagle
.LONG TERM...Friday through Monday...The polar jet stream will start
off the extended forecast period aimed toward western Canada, but it
will begin to sag southward Friday. This should allow for stronger
onshore flow after another warm afternoon Friday. Shower chances
increase for the weekend as the jet stream continues to push south
into Washington and Oregon. Model guidance continues to carve out an
unseasonably deep and cool upper level low or trough over the Pac NW
this upcoming weekend, which should lead to another round of
late-season cool and showery weather which may continue into early
next week. Weagle
&&
.AVIATION...VFR conditions will across the forecast area through
12Z Tuesday under clear skies. The latest model guidance
continues to show a thermally induced surface trough extending
northward up the Oregon coast, before moving inland Tuesday
afternoon. There is a possibility for localized IFR/LIFR fog
to develop around KONP after 12Z Tuesday, as depicted by some of
the high resolution model soundings. Confidence for fog
development at KONP is low to medium at this time.
Interior locations are expected to maintain VFR conditions
through 06Z Wednesday. Gusty northwest winds will likely develop
along the coast Tuesday afternoon and linger through the evening
hours. -TK
KPDX AND APPROACHES...VFR conditions will continue through 06Z
Wednesday. Scattered high clouds should begin moving into the
area late Tuesday morning into the afternoon. Sea breeze looks to
move into KPDX by 00z, leading to a few gusts around 15 kt or so.
-TK
&&
.MARINE...Thermally induced surface trough remains over the
north California and south Oregon waters through Tuesday evening.
Expecting small craft advisory winds to develop in zone PZZ275
in the next few hours and then extend into the remaining zones
this evening. Gusts to 30 kt possible over PZZ275 and PZZ255
through tonight. Small craft advisory wind conditions expected
to persist through tonight, with zone PZZ275 holding onto small
craft winds through Tuesday morning.
A shortwave trough is forecast to move across the waters late
Tuesday through early Wednesday. This will weaken the thermally
induced surface trough resulting in lighter wind speeds. Longer
range guidance shows the thermal trough returning Thursday, which
will likely bring back small craft advisory winds to our waters.
General seas will be 4 to 7 ft through the middle of the week.
Model wave guidance shows the potential for 9 to 11 ft seas
developing next weekend. /42
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until midnight PDT tonight for coastal
waters from Cape Shoalwater WA to Florence OR out 10
NM.Waters from Cape Shoalwater WA to Cascade Head OR from
10 to 60 NM.
Small Craft Advisory until 9 AM PDT Tuesday for Waters from
Cascade Head to Florence OR from 10 to 60 NM.
&&
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until midnight PDT tonight for coastal
waters from Cape Shoalwater WA to Florence OR out 10
NM.Waters from Cape Shoalwater WA to Cascade Head OR from
10 to 60 NM.
Small Craft Advisory until 9 AM PDT Tuesday for Waters from
Cascade Head to Florence OR from 10 to 60 NM.
&&
$$
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Area Forecast Discussion
National Weather Service Shreveport LA
1003 PM CDT Mon Jun 22 2020
.SHORT TERM.../Tonight/
All remains quiet this evening and should remain so for the
majority of the overnight hours, as the weak outflow bndry from
the early morning convection has dissipated, although an area of
bndry lyr moisture pooling persists where this bndry became
stationary earlier this afternoon over portions of NE TX/NW LA/SW
AR. While ample instability remains along this SW to NE axis, the
region remains on the subsident side of a shortwave trough over
the Lower MS Valley that brought about the strong/severe
convection and localized flooding to portions of SW AR last
night/early this morning. However...we wait for the convection
well to our NW over the TX Panhandle associated with the next
developing shortwave trough along the base of the larger longwave
trough currently digging through the Midwest and Great Lakes
Region.
This trough remains progged to slide SE into the Srn Plains
overnight, where moderate instability resides indicative of
MLCapes of 2000-3000+ J/Kg, which will be maintained by a
developing 25-30+kt Srly low level flow over Wrn TX and the Hill
Country. The 00Z NAM has initialized well with the ongoing
convection over the TX Panhandle this evening, which slides the
MCS SE across WCntrl into N TX late tonight, with increasing
moisture convergence along an H850 trough (and inverted sfc
trough) near and just S of the Red River of N TX resulting in this
convection building E into ECntrl TX by or just prior to daybreak
Tuesday. In addition, the 00Z NAM suggests that H850 theta-e
ridging will develop over portions of Ern OK late tonight near
the primary shortwave trough which may result in isolated to sct
convection developing near or N of McCurtain County. With the last
few runs of the HRRR suggesting a slower movement of the MCS into
the region, as well as the latest CAMs, have dropped pops this
evening and significantly lowered pops to low chance for the Nrn
sections of SW AR/SE OK and extreme NE TX late tonight. Have also
taken out pops for the remainder of tonight across Lower E TX/N
LA/Scntrl AR, but did maintain the pop forecast as is Tuesday as
convection should quickly expand E across much of the region after
daybreak through midday/early afternoon along and just S of the
weak sfc trough extending into Srn AR. Also made a few minor
tweaks to min temps, mainly to lower them in a few places where
they were already near their min temps. Otherwise, the remainder
of the forecast is in good shape.
Zone update already out...grids will be available shortly.
15
&&
.PREV DISCUSSION... /issued 653 PM CDT Mon Jun 22 2020/
AVIATION...
VFR conditions will continue this evening through much of the
overnight hours, with a few cu and extensive areas of cirrus
expected to linger over the area. However, a Srly low level flow
should result in areas of low MVFR/possibly IFR cigs
developing/spreading N after 08Z, possibly affecting the E TX/N LA
terminals by or prior to 12Z Tuesday, with these cigs affecting
the SW AR terminals after 12Z near a weak sfc trough that will
extend from the Red River of Srn OK/N TX into SW and SCntrl AR.
These cigs should gradually lift through mid to late morning,
although a decaying complex of convection over WCntrl and N TX
will shift ESE and possibly affect portions of E TX by/after 12Z,
with the remnant cold pool or outflow bndry potentially enhancing
convective development farther E across the region during the day
with the onset of diurnal heating. Have maintained VCTS for E TX
Tuesday morning, while delaying VCTS for the TXK/SHV terminals
until late morning as this convection may build E closer to the
sfc trough to the N as it drifts S through the day. Believe that
the convection will be widespread enough to warrant prevailing
TSRA with vsby reductions and MVFR cigs at the TYR/GGG/TXK/ELD
terminals by early afternoon, with this convection eventually
expanding ESE across much of N LA during the afternoon. Thus, a
mix of VFR/MVFR cigs will be possible during the afternoon,
whereas the lower cigs will be colocated with the convection. SSW
winds 5-10kts tonight will persist through Tuesday, but become VRB
and possibly gusty in/near the convection. /15/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 74 82 69 86 / 10 90 60 40
MLU 72 84 69 84 / 10 90 70 60
DEQ 73 80 62 89 / 30 70 10 0
TXK 73 79 66 86 / 20 80 20 10
ELD 72 81 65 85 / 10 90 40 20
TYR 73 80 68 86 / 30 90 40 20
GGG 73 81 68 86 / 10 90 50 30
LFK 73 86 69 86 / 10 90 80 70
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
15
Area Forecast Discussion
National Weather Service San Angelo TX
609 PM CDT Mon Jun 22 2020
.AVIATION...
/00Z TAFS/
Isolated to scattered showers and thunderstorms are possible
across the Concho Valley this evening, which may affect the KSJT
and KBBD TAF sites. A line of showers and thunderstorms may then
move through the area between 06Z and 13Z. Any of these storms may
produce heavy rainfall, large hail, and strong gusty winds. Most
of this activity will move south of the area by mid morning. In
addition, stratus will develop between 10Z and 12Z, resulting in
MVFR ceilings. VFR conditions will return by mid to late morning.
Gusty south to southeast winds early this evening will decrease
late this evening. A cold front will move through the area Tuesday
morning, resulting in north to northeast winds around 10 knots.
&&
.PREV DISCUSSION... /issued 225 PM CDT Mon Jun 22 2020/
SHORT TERM...
(Today and Tonight)
A messy forecast pattern appears to be on tap through at least
tomorrow morning. As of early Monday afternoon, a warm and moist
Gulf airmass had established itself across much of west Texas.
Temperatures were in the upper 90s on their way to the low 100s,
with dewpoints in the upper 60s. A Heat Advisory remains in effect
until this evening for the Concho Valley and Crockett County.
Meanwhile, an area of low pressure was noted along the Texas/New
Mexico border, while a surface trough extended out from this area
through the Concho Valley, with a frontal boundary across southern
Oklahoma. The upper levels are in a persistent northwest flow
pattern at 500mb, which tends to make forecasting convective
coverage much more challenging this time of year.
Midday RAP soundings and SPC Mesoanalysis show widespread areas
of over 5000 J/kg of CAPE, with 1500 J/kg of Downdraft CAPE, along
with Effective Shear of 30-40KT. As a result, SPC has a Slight
Risk across much of the Southern Plains today. The one fly in the
ointment is how much the cap will hold this afternoon. Temps at
700mb were holding right at 14 deg C. However, the aforementioned
surface trough may provide just enough convergence to break
through the cap, allow for a few cells to develop this afternoon.
Anything that develops could produce locally damaging wind gusts
and possibly large hail.
The best chances for precipitation appear to be tonight, when a
substantial shortwave embedded in the northwest flow aloft will
push southeastward across West Central Texas. Assuming not much
change to the current airmass, aside from some diurnal cooling,
and if thunderstorms can get organized late this evening across
the South Plains, a large thunderstorm complex should push through
West Central Texas sometime after midnight. This complex would
have the potential to produce locally damaging winds, heavy rain,
and persistent lightning. Otherwise, warm and humid conditions
will continue overnight.
By sunrise tomorrow, the 500mb shortwave should help to move a
cold front southward and push any nocturnal precipitation further
east. In it`s wake, a slightly cooler airmass will move in, with
cloud cover hanging on through about midday. Still, temperatures
are expected to reach the low 90s in the afternoon.
SK
LONG TERM...
(Tuesday Night through next Monday)
A stationary cold front/outflow boundary is expected to settle
south of our forecast area by Tuesday night. This boundary, along
with another shortwave moving southeast through west Texas will
bring another chance for showers and thunderstorms, mainly for
areas southeast of a Sweetwater to Brownwood line. However,
thunderstorms can`t be ruled out anywhere due to outflow
boundaries being laid down by previous convection serving as
potential focal points for new thunderstorms to develop off of.
With overnight convection Tuesday night expected to add new
outflow boundaries, and the shortwave/potential MCV moving slowly
through southern parts of Texas, additional thunderstorms will be
possible through Wednesday, mainly for the southern half of the
area. Any of the storms produced during these events will have the
potential for locally heavy rainfall with a very humid atmosphere
in place. Although widespread severe weather is not expected, a
few of the storms could become strong and produce small hail,
and/or strong, gusty winds. Highs Tuesday and Wednesday should be
the coolest of the week overall, in the mid 80s to lower 90s.
The forecast will trend drier through the end of the week and into
next weekend, with moderating temperatures. Highs from Thursday
through the weekend should warm slowly back into the 90s areawide.
20
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 70 88 67 88 / 70 30 20 10
San Angelo 74 93 68 90 / 30 20 30 30
Junction 74 93 67 90 / 30 30 40 40
Brownwood 71 88 66 89 / 60 40 30 20
Sweetwater 69 89 67 88 / 50 20 20 20
Ozona 74 94 69 90 / 10 20 30 40
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 7 PM CDT this evening for Coke-Concho-
Crockett-Irion-Runnels-Sterling-Tom Green.
&&
$$
Daniels