Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/19/23
Area Forecast Discussion
National Weather Service La Crosse WI
1020 PM CDT Sun Jun 18 2023
.DISCUSSION...(This evening through Sunday)
Issued at 200 PM CDT Sun Jun 18 2023
Key Messages:
- Showers and storms most numerous through early evening,
decreasing in coverage overnight. Lightning to those outdoors is the
main impact. Some areas may get lucky and see repeat downpours and
rain totals over 1/2 inch.
- Warm and dry forecast for next week is still on track, worsening
the drought situation.
Showers and Thunderstorms Most Numerous Through Evening
Convection has been expanding this afternoon in the ML CAPE axis
extending into the area from eastern Iowa. Eventually expecting
scattered to numerous showers and storms to form in this axis, but
as we move into the early evening, the CAPE will start to diminish
with a decrease in coverage expected. The RAP does show some weak
instability and moisture transport holding on through the night as
it moves to the north/northeast. This may be enough to keep some
scattered showers going through much of the night for areas along
and north of Interstate 94 into north-central Wisconsin. Some decent
downpours should occur with the stronger activity yet this afternoon
with precipitable water amounts around 1.5 inches and radar data
suggesting rates around a half inch per hour. Outside of the
stronger activity though, while some rain can still be expected,
amounts will generally be a quarter inch or less.
On Monday a lingering low-level moisture axis is suggested in the
guidance to be placed along a broad Eau Claire WI to Decorah IA
axis. With daytime heating, the air mass has little cap by afternoon
and there is some hint of some very weak low-level moisture
convergence between an east/southeast drier, ridge building flow and
the resident southerly flow within the axis. This may be enough to
trigger a few showers or a storm. Have held a low chance of
showers/storms /20%/ near and north of I-90 in the afternoon. It is
well agreed in the model guidance that this drier, ridge building
push of low-level air continues to scour west Monday night,
stabilizing the area for the week.
Tuesday through Sunday: Drought Building Weather
Bottom line for next week is that drought conditions will worsen
across the area with above normal temperatures and lower afternoon
relative humidities /30-40%/ promoting drying soils and vegetation.
This forecast period remained stable with high predictability
suggested in the ensemble families...thus very little change made
with this update. Major amplification of the North American flow
pattern is expected next week with deep anomalous troughing over the
west with ridge building from the southern Plains into the Great
Lakes. Extreme heat probabilities and anomalies from the 18.00Z
ECMWF/NAEFS ensembles remain in the "just above normal" category and
behaved. An anomalous easterly flow signal is seen in low-levels to
the southeast over IL and srn Lake MI, which provides an air mass
source region that is a somewhat cooler, drier flow as it advects
northwest into our area on southeast flow. So, the warmth builds to
upper 80s and lower 90s and holds with a stagnant pattern through
the week, with the NBM mean dewpoints in the 55-62F range...quite
comfortable for June warmth. This will keep heat index values very
close to the air temperature.
Rain and storm chances begin to increase late week as the large
scale ridge begins to break down at higher latitudes. However there
is low predictability and various ensemble solutions on when and how
this occurs. In the big picture as the ridge breaks down over the
Great Lakes and southern Canada, more zonal flow and shortwave
trough energy should affect the region. Rain chances would build
southeast with time through the weekend.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1020 PM CDT Sun Jun 18 2023
CIGS: mostly mid level VFR cigs through the night, with models
pushing to scatter those out Monday morning. RAP/NAM12 bufkit
soundings suggest sct-bkn cu deck will develop in the afternoon with
lingering moisture, weakly convergent boundary and daytime heating
(instability). Any potential cig looks to be VFR at this time.
WX/vsby: scattered -shra/ts continue at late evening with a ribbon
of instability, upper level shortwave and low level jet helping to
trigger some more convection. Much more miss than hit, and CAMS
still favor a decrease in this activity/shift north as we move into
the overnight. Might have to continue VCSH at the TAF sites through
06z, but favoring dry after that.
WINDS: south/southeast into Monday night, generally 10 kts or less.
&&
.FIRE WEATHER...
Issued at 200 PM CDT Sun Jun 18 2023
An easterly wind flow and air mass source region from the east will
bring anomalously lower dewpoints for June into the districts next
week. This, combined with above normal temperatures, will bring
afternoon minimum relative humidity values into the 30-40% range
next week which will help further dry fuels. Winds appear to remain
below 15 mph for the week. Rain chances, albeit low, increase for
next weekend as the ridge pattern begins to break down.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...04/Baumgardt
AVIATION.....Rieck
FIRE WEATHER...Baumgardt
Area Forecast Discussion
National Weather Service Duluth MN
658 PM CDT Sun Jun 18 2023
.DISCUSSION...(This evening through Saturday)
Issued at 522 PM CDT Sun Jun 18 2023
Summary: Chances for showers and isolated thunderstorms will
continue this evening with dry and hot conditions expected for
much of the week. Rain chances return at the end of the period as
a cold front tries to work in.
Low pressure was located over Iowa this afternoon with showers and
isolated thunderstorms over eastern and northern Minnesota and
western Wisconsin. Much of this activity was being driven by
daytime heating and a shortwave aloft. Models have been struggling
with this activity with synoptic models broadbrushing rainfall
across the region and CAMs doing poorly with coverage and
intensity. Leaned on the HRRR with the first pass through the
forecast before tweaking later upon the arrival of the 18z NAMNest
which seems to have a decent handle on the activity in
Koochiching County and what is moving into our southern zones in
northwest Wisconsin. This activity will continue to drift north-
northeast this evening and diminishing with the loss of daytime
heating. No strong or severe storms are expected with marginal
shear in place. Northwest Wisconsin will see the best chance for
rainfall this evening, but amounts will be light and far from what
is needed to reverse course on the increasing drought conditions.
A few showers and isolated storms may linger into Monday morning
as the shortwave exits the region. Upper level ridging and high
pressure to our east will then act to keep dry conditions in place
for much of the week. Southerly flow at the surface over the
region on the backside of the high off to our east will lead to
increasing temperatures with highs reaching the 80s and 90s for
midweek. Over the latter portion of the week and heading into the
weekend, a cold front and upper trough will attempt to move out of
the Northern Plains and into the Northland. However, eastward
progress will be slow as it runs into the strong high to the east.
Rainfall chances will be possible Friday into the weekend along
with cooler temperatures behind the front as high top out in the
70s and 80s. The upper flow pattern then looks to become a bit
more favorable for bringing storms systems through the region
heading out of the weekend and into next week. Expectations should
be tempered, however, in regards to rainfall. Systems in this
trajectory tend to have less moisture to work with, so significant
rainfall will continue to be hard to come by.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 658 PM CDT Sun Jun 18 2023
VFR ceilings are present across the area, with some scattered
showers across east-central Minnesota in to northwestern
Wisconsin. Also a couple isolated showers near INL that should
exit by 01-02Z. Only TAF site with prevailing shower mention is
HYR this evening and overnight. Have also introduced VCSH for DLH
this evening due to light showers moving north out of northwestern
Wisconsin. Interaction of these showers with the lake breeze could
limit rainfall potential and duration at DLH. Models bring in
lower ceilings and visibilities tonight into Monday morning,
though the fog and IFR ceiling potential may be more limited to
areas that see rainfall today. Mainly kept MVFR ceilings for TAFs
tonight into early Monday morning, with the best potential for IFR
ceilings/MVFR visibilities at BRD and DLH. A return to VFR
conditions is expected by midday on Monday.
Winds remain light and variable through tonight, then turn
southeasterly around 6-10 knots with occasional gusts to 10-15
knots during the late morning and afternoon on Monday.
&&
.MARINE...
Issued at 522 PM CDT Sun Jun 18 2023
Northeasterly winds are expected to prevail through the forecast
period with gusts to around 20 knots possible through early this
evening and again Monday afternoon, mainly along the North Shore.
A few gusts to around 25 knots cannot be ruled out at times, but
these are expected to be few and far between. These persistent
northeasterly winds will lead to waves of 2 to 4 feet at the head
of the lake with waves generally under 2 feet elsewhere. A few
isolated thunderstorms will be possible through Monday morning,
but only a few isolated lightning strikes will be possible.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 54 73 54 81 / 30 0 0 0
INL 56 81 63 90 / 20 0 0 0
BRD 60 87 67 90 / 20 0 0 0
HYR 59 84 61 88 / 60 10 0 0
ASX 54 79 57 87 / 30 20 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
DISCUSSION...BJH
AVIATION...Rothstein
MARINE...BJH
Area Forecast Discussion
National Weather Service Peachtree City GA
938 PM EDT Sun Jun 18 2023
.UPDATE...
Issued at 929 PM EDT Sun Jun 18 2023
Strong shortwave across the Lower Mississippi River Valley will
move east overnight. An area of showers and thunderstorms
associated with the shortwave should begin to approach the AL/GA
line after 06Z. The hi-res models have been fairly consistent with
the timing of this system, however they are having issues
resolving whether the system will be an unorganized area of
convection or a linear line.
The early morning convection should (hopefully) at least stabilize
portions of northern GA through the early afternoon. Depending
upon how widespread and how far east the early morning convection
makes it, portions of the southern CWA could be temporarily
stabilized also. Do expect additional showers and thunderstorms
tomorrow afternoon, but he hi-res models are currently a mess.
Development and timing of any afternoon convection will depend
upon what the early morning convection does. Have tried to convey
a brief lull in convection during the mid/late morning, but do
expect activity to pick up once again in the afternoon...but
initiation time/place is uncertain as of now.
&&
.SHORT TERM...
(This evening through Monday)
Issued at 316 PM EDT Sun Jun 18 2023
Challenging forecast for the short term. In the very near term,
showers have finally started to push into portions of western GA
this afternoon, though they have been mainly isolated to I-85 and
points southward so far. These are associated with the remnants of
storms that pushed through portions of MS and AL last night into
early this morning, but are likely being aided in remaining
around by some WAA and a small lower to mid level mesovortex
likely also created by this mornings convection. How well these
remain together will be a question of how quickly the very dry
airmass in place from this morning`s sounding can vacate the area
and/or moisten. Best chances will be across west GA through the
evening hours, but have left in some afternoon PoP chances across
most of the CWA. Beyond these showers moving in, enough surface
moisture is coming in to allow for at least some quick pop up
storms, especially in central GA where moisture is better overall
and CAPE values are rising to at or above 1000 J/kg.
Tonight, the CAMs have quite the split on how things are going to
play out. Upper level system that is expected to stall over the area
for the week in pushing in. Moisture is expected to continue
streaming into the area from the Gulf and Atlantic. If there is some
level of clearing out of the convection like the HRRR has been
showing late this evening, we likely will see the baroclinic
boundary associated with the repeated rounds of rainfall to our
south able to lift a bit into the CWA. As the upper level system
continues to move in, eventually convection should begin to fire
upstream in TN, MS, and AL. This may congeal into a bit of a more
organized line as it pushes into the CWA, bringing some late
night/early morning storms and heavy rain. Some other models are
less aggressive, keeping storms and the lines a bit more to our
south. This forecast package has leaned a bit into the HRRR, as it
seems to be performing well overall with convective solutions the
past 24 hours. That said, can see how its forecast can go wrong,
especially if gulf based convection continues to hang on for longer
than expected.
Not expecting a widespread severe weather outbreak even if a line of
storms does form. Better sfc based instability and shear will still
be further south, with ensemble HREF mean showing only 500-1000 J/kg
of instability within the CWA overnight. That said, 0-1 km SRH is in
the 100-200 m2/s2, so hard to rule out some stronger updrafts
capable of some damaging wind gusts or hail - if storms can end up
forming.
Otherwise, the rest of the forecast for Monday will be dependent on
what unfolds overnight. It is likely that we will see additional
convection pop up through the afternoon and into the evening as the
upper level low slowly moves into the area and moisture continues to
stream in. But where and when, you know, the important details, are
a bit more challenging to pin down. One thing a bit more certain
is that cloud cover should keep highs down in lower to mid 80s
across the CWA, continuing our trend of relatively cooler early
summer days.
Lusk
&&
.LONG TERM...
(Tuesday morning through next Saturday)
Issued at 316 PM EDT Sun Jun 18 2023
Key Messages:
- Cloudy and rainy weather is forecast this week, with rainfall
totals likely (> 90% chance) exceeding 2 inches by next weekend.
- Expect below average temperatures all week, with high temperatures
running 5 to 15 degrees below average.
Dreary Weather Tuesday through Next Weekend:
With an omega block over the Lower 48 and a nearly stationary upper
level trough over Alabama and Mississippi pumping moisture northward
from the Gulf, it will feel like we are living in a "southern
version Seattle" this week. Though it is hard to imagine us not
seeing the sun for six straight days in late June, that is what a
good portion of the ensemble guidance is leaning towards. The mean
cloud cover from the 80 EPS and GEFS members keeps the region under
80 to 100 percent cloud cover through at least Sunday. With the
cloud cover will come the consistent threat of rain, due to a
persistent feed of moisture from the Gulf and diffluent flow aloft.
Our going forecast has rainfall chances at or above 20 percent for
every 6 hour block between Tuesday and Saturday. If we zoom in on
the Atlanta area, only 3 of the 80 EPS and GEFS ensemble members
project less than 2 inches of rain in the region through the end of
next weekend. Meanwhile the average rainfall from all 80 EPS and
GEFS members is hovering near 3.5 inches. This trend in the guidance
holds true for other areas in central and north Georgia, though rain
totals are slightly higher across the eastern half of the state.
Thus our forecast confidence is high regarding the occurrence of
rainfall totals in excess of 2 inches by the end of the week. In
some localized areas where thunderstorms either train or are
persistent over several days rain totals in the 5 to 8 inch range
could occur. As such our flooding risk will be higher than normal
all week and the WPC has the region under either a slight (Level 2
of 4) or marginal (Level 1 of 4) risk for excessive rainfall each
day through Friday. One good thing about this particular event looks
to be how the rain is spread out over 4 to 6 days. This should limit
the flood threat to some degree, though we may start to see some
limited river rises by the later part of the week if these rain
totals come to fruition.
All of the cloud cover and rain will help limit temperatures over
the upcoming week. Our going forecast keeps high temperatures 4 to
14 degrees below seasonal averages through Saturday. The coolest
days could end up being Wednesday and Thursday when daily highs may
only reach the mid to upper 70s across north Georgia (including
Atlanta).
Albright
&&
.AVIATION...
(00Z TAFS)
Issued at 653 PM EDT Sun Jun 18 2023
Hi-res convective models are in good agreement with an area of
shra moving in around 08Z MON. There should be a lull in
convection after the early morning activity, and afternoon/eve
shra/tsra will be possible. Do think thunder will fire up first
tomorrow afternoon south of where the morning activity moves.
Winds will likely flirt with due south tonight and briefly go SE
early Mon. Winds should go back to the SW mid to late morning MON.
//ATL Confidence...00Z Update...
Med confidence on convective trends tomorrow afternoon. Med-high
confidence remaining trends.
NListemaa
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 68 79 67 80 / 60 70 50 90
Atlanta 70 81 69 81 / 70 70 50 90
Blairsville 63 75 63 73 / 70 70 50 100
Cartersville 68 83 67 81 / 80 50 40 90
Columbus 71 83 69 85 / 60 70 40 80
Gainesville 68 78 68 78 / 70 70 50 90
Macon 70 83 68 84 / 30 70 50 90
Rome 70 85 68 83 / 80 50 40 90
Peachtree City 68 83 67 83 / 70 60 40 90
Vidalia 72 87 70 85 / 30 70 70 90
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...NListemaa
LONG TERM....Albright
AVIATION...NListemaa
Area Forecast Discussion
National Weather Service Glasgow MT
212 PM MDT Sun Jun 18 2023
.DISCUSSION...
AFTERNOON DISCUSSION:
Showers have started to move into northeastern Montana, moving
towards the northeast along Phillips and Petroleum counties. As
the afternoon and evening progresses, these showers are still
expected to become more widespread across our CWA.
Regarding the severe potential, the late morning run of the CAMs
have become a bit more favorable compared to earlier. Not
currently expecting major happenings but also cannot rule out a
spicy storm here or there producing gusty winds and sub-severe
hail. The good news is, the severe risk is expected to be
completely diminished by midnight and possibly as early as 10 PM
if the HRRR is to be believed.
-thor
PREVIOUS DISCUSSION:
Today into tonight:
Current radar from Great Falls indicates showers moving across
western MT, which will eventually reach northeast MT by early
afternoon as the upper level trough moves into the intermountain
west. A shortwave trough will eject through the main trough, and
an accompanying cold front will turn winds from the southeast to
northwest. Since there is not low-level moisture advection
expected, surface CAPE values will likely remain below 750 J/kg,
according to the 00Z and 06Z NAM NEST and HRRR. However, steep
low-level lapse rates and strong forcing for ascent may work in
tandem to aid in convection. These storms could produce gusts to
50 mph and sub- severe hail through the late evening.
Monday into Monday night:
The setup will remain the same as the previous day, but with the
upper-level trough and moisture aloft already in place, higher
precipitation accumulations are expected by 06Z Tuesday across the
area than for the activity today. Lapses rates will not allow for
almost any CAPE to develop in the afternoon based on CAMs, so
showers are mainly expected. Anywhere from one tenth to three
quarters of an inch are possible across the area.
Tuesday:
The upper-level trough will remain over the region, so another
round of showers and thunderstorms is possible. However, there
appears to be less organization and strength to this event since
there appears to be no shortwave trough accompanying the trough.
There is high confidence (80 percent) that precipitation
accumulations will be less than on Monday.
Wednesday and beyond:
Although precipitation chances exist for Wednesday and Thursday,
recent monitoring of the long-term forecast helps indicate
moisture advection and decent bulk wind shear ahead of an oncoming
trough. This may bring severe weather into play, but high
uncertainty exists on the timing of this trough.
-Stoinskers
&&
.AVIATION...
UPDATED: 2000Z
FLIGHT CAT: Mainly VFR, MVFR/IFR possible with thunderstorms.
DISCUSSION: Showers have begun moving into northeastern Montana
and will continue to spread eastward as the day progresses. For
the most part these showers will remain light, however, there is
a chance for some stronger thunderstorms after 00Z which may
reduce conditions to MVFR or even IFR. Showers and thunderstorms
are expected to diminish for KGGW and KOLF by 04Z and KSDY and
KGDV by 07Z.
WINDS: West/northwest at 10 to 20 kts gusting up to 30 kts this
afternoon/evening before becoming light and variable after 06Z.
Winds may be erratic and gusty with thunderstorms.
-thor
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service Grand Rapids MI
756 PM EDT Sun Jun 18 2023
LATEST UPDATE...
Aviation
.SHORT TERM...(This evening through Monday night)
Issued at 248 PM EDT Sun Jun 18 2023
No changes to previous forecast thinking, although we did lower
Monday afternoon dewpoints and relative humidity values a bit based
on the expected dry east-northeasterly flow that will be established
by then. Model guidance can sometimes have a slight moist bias
(referring to humidity, not precipitation) in these situations.
With respect to near surface smoke, recent HRRR runs indicate a
pronounced westward push of the greater concentrations well into
Lake Michigan. This should help our air quality across much of
southwest Lower Michigan for Monday/Juneteenth.
.LONG TERM...(Tuesday through Sunday)
Issued at 248 PM EDT Sun Jun 18 2023
There are three primary focus areas in the long term period: fire
weather potential Tuesday into Wednesday, degree of warmth mid to
late week, and rain chances by the weekend.
Fire weather conditions may come in to play perhaps on Tuesday and
Wednesday. This is due to rising temperatures in the mid 80s to
around 90 and lower RH values to 30% or less during the afternoon
hours, but in concert with wind gusts that could exceed 20 mph.
Given the dry antecedent conditions and current Fire Danger Rating
(FDR) for conifers ranging from high to extreme across much of the
area, fire development and fire spread could be elevated on these
days.
Looking at EPS percentiles and spread for max temps Tuesday into
Thursday, high confidence exists for upper 80s to low 90s. Given the
Rex Block pattern in place, very little spread is shown in the
ensemble membership with respect to the max temps. As noted in the
previous AFD, heat index readings should be held at or below the
actual air temperatures given low dewpoints and RH values. Sunshine
will dominate this period, though the usual caveat of possibly hazy
skies due to Canadian wildfires will once again apply.
The upper low across the SE United States that will be wedged under
the upper ridge across the Great Lakes may try to make a
northwestward movement by late in the week or weekend. Depending on
the system`s propagation, we may see some enhanced low level
moisture and rising PWATs develop. This far out, a variety of
outcomes are possible, including a total miss to our south and east
if it does not far enough north. This would have implications on how
warm it may get during this period as well. EPS 25th percentile max
temps for GRR Saturday into Sunday are in the low to mid 90s. That
would not materialize if the upper low moves in. The NBM is
currently featuring 20%-40% chances for some showers and
thunderstorms Friday into Sunday. So, chances are not great at this
point, and ideally we would want to see better ensemble agreement on
the likely outcome late week, but this may not come into focus for a
couple days yet.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 756 PM EDT Sun Jun 18 2023
VFR weather continuing tonight and Monday with only high level
clouds (abv 20k ft) expected. There was some shallow fog around
early Sunday morning (08Z-12Z) which produced 3-5 mile vsbys, and
while that cannot be ruled out again early Monday morning, the
air is drier so did not include any fog in the TAFs.
The vsby reduction at MKG (5 miles) due to persistent haze is
expected to eventually improve later tonight into Monday as drier
easterly/offshore flow becomes established.
&&
.MARINE...
Issued at 248 PM EDT Sun Jun 18 2023
No headlines are anticipated due to weak flow. Winds will increase a
bit on Monday/Juneteenth and Tuesday, but the offshore direction
will mitigate nearshore wave growth.
We continue to observe light haze along the lakeshore and this is
borne out by a persistent 5 mile visibility reported at the Muskegon
ASOS. Our concerns for marine fog are greatly reduced due to
impressive warming of water temperatures /mid to upper 50s F/ at
beaches. Additionally, a north-south oriented maximum of near
surface smoke concentrations that`s currently located along the
lakeshore region is expected to push west out of the nearshore
waters on Monday/Juneteenth as easterly flow begins to take hold.
&&
.CLIMATE...
Issued at 248 PM EDT Sun Jun 18 2023
Our long term climatological stations certainly reveal the unusual
nature of this drought, with many sites in the top 3 driest May-June
period so far, including Grand Rapids, Lansing, Muskegon, and
Kalamazoo. If Grand Rapids (GRR) does not get at least 0.26" of rain
through the end of this month, we will rank 1st driest May-June
period on record ahead of the May-June 1988 drought, which only saw
1.32" at the time. Currently GRR is at 1.05" from May 1 through
today.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
SHORT TERM...TJT
LONG TERM...Hoving
AVIATION...Meade
CLIMATE...Hoving
MARINE...TJT
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
944 PM CDT Sun Jun 18 2023
...New MESOSCALE UPDATE...
.MESOSCALE UPDATE...
Issued at 932 PM CDT Sun Jun 18 2023
After the morning convection scoured out the airmass, afternoon
heating resulted in a rapid recovery and local radars were lit up
at mid evening with storms over our east and northeast Mississippi
zones. Much of this activity was producing severe weather with
wind and tornadoes being the main threat although hail and locally
heavy rain was also occuring with the strongest storms. This
activity was moving to the east and additional development is
expected during the next several hours. Some area rivers are in
flood from the rainfall over the last several days and in addition
to the severe weather threat, flash flooding will also be possible
over east Mississippi the next several hours. The chance for rain
has been adjusted based on radar trends and temperature curves
were adjusted based on rain cooled areas. /22/
&&
.DISCUSSION...
Issued at 356 PM CDT Sun Jun 18 2023
Overview...
Severe storms will continue today and tonight as a short wave is
fueling an MCS and pushing southeastward into a very unstable
environment. 5800 j/kg of CAPE have been observed along with very
steep midlevel lapse rates around 8 c/km. Unseasonably strong deep
layer shear is helping to maintain these storms and and stagnant
pattern is fueling multiple rounds over several days. This is likely
to continue into tonight until Monday as an upper low traverses
across Tennessee and Alabama. This should turn flow northerly
across the area and advect drier air and should bring reprieve
from this current unsettled pattern for much of the area, but it
should be noted that climatology suggests it may be difficult to
maintain a drier airmass. As the upper low influences our area,
the stalled frontal boundary that has been in the vicinity of the
I-20 corridor should push south and west. Given available moisture
and instability, storms are still possible Monday along this
boundary in far southwest Mississippi and eastern Louisiana.
Throughout the week, temperatures and dewpoints should be
relatively lower providing some relief for much of the area.
Today and tonight...
Severe storms from this morning have cleared the area and skies are
clearing from west to east. Mid to upper 70s dewpoints are being
observed in southern Louisiana and this plume of moisture is
being advected into our area as evidenced by satellite imagery and
observations across the southeast. This should set up a nice
recovery of airmass ahead of a deepening low pressure system. As
of 1:40 PM, surface pressure measured was 1010mb and is falling
quickly, with modeled pressure falls to be as much as 6 mb in 6
hours. Many CAMs are in agreement with an intense QLCS that pushes
through later this evening and into tonight. Favorable convective
parameters (3500+ j/kg CAPE, vertical totals 31, midlevel lapse
rates 8 c/km) will be supportive of damaging wind gusts and large
hail once again. However, unlike previous events, southeasterlies
are being observed across the area as a boundary pushes northward
from southern Louisiana, which could increase tornado potential
with favorable low level shear. HRRR depicts 200-300 m^2/s^2 0-1
km SRH and WSW oriented shear vectors. CU fields are observed
along the boundary and mesoanalysis shows 5000-7000 j/kg of SBCAPE
across southern Louisiana, which will be supportive of rapid
upscale growth. /SAS/
Monday through next weekend...
Looking ahead to tomorrow, a residual boundary from tonight`s
convection will serve as the main focus for a corridor of yet
another round of storms, with damaging wind gusts and large hail the
primary threats given 3500+ j/kg of CAPE and vertical totals 28-31.
There is however notably weaker shear as the pattern begins to wind
down and this may preclude extreme intensity, however strong to
severe storms are still probable along this boundary. Thankfully the
focus will be south and west of most of our area, however eastern
Louisiana and extreme southwest Mississippi may be impacted.
As mentioned previously, the pattern should wind down this week,
replaced by a rex block pattern that should relieve us from most
activity in the midst of an upper low advecting drier air on the
backside. Climatology dictates however that maintaining a drier
airmass will be difficult and rain and storms are still possible
daily, therefore have maintained pops. Despite daily pops, the
upcoming week should feature more seasonable norms. /SAS/
&&
.AVIATION...
(00Z TAFS)
Issued at 645 PM CDT Sun Jun 18 2023
Local radars showed TSRA developing over the western and cntrl MS.
This activity will spread east northeast across the area affecting
most TAF sites this evening. Away from TSRA activity, VFR
conditions wl continue. After 06Z as the TSRA activity diminishes,
MVFR cigs are expected to develop and continue through 16Z before
improving to VFR by 18Z. The coverage of aftn and evng TSRA Monday
wl be across the se half of hour CWA. /22/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 72 91 70 90 / 60 30 20 40
Meridian 70 90 68 91 / 70 40 20 40
Vicksburg 72 91 72 89 / 60 10 20 30
Hattiesburg 75 93 72 91 / 40 70 30 60
Natchez 73 94 73 90 / 50 20 30 50
Greenville 70 90 70 90 / 60 0 10 10
Greenwood 71 90 70 90 / 70 0 10 10
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Flood Watch until 7 AM CDT Monday for MSZ026>033-036>039-042>046-
048>052-054>058-062>066-072>074.
LA...None.
AR...None.
&&
$$
SAS20/22
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
628 PM CDT Sun Jun 18 2023
.SHORT TERM...
Issued at 204 PM CDT Sun Jun 18 2023
Through Monday night...
Regional water vapor imagery depicts several compact MCVs oriented
just west of the Mississippi River Valley from near the Twin Cities,
MN to just west of St. Louis, MO. Each circulation is within a
narrow moist sector bounded by I-35 and the Mississippi River where
surface dew points are in the low to mid 60s and mid-level lapse
rates range from 6 to 7 K/km. Little to no capping has allowed for
scattered showers and storms to develop in close proximity to each
MCV primarily, again, west of the Mississippi River. Meanwhile, a
surface high pressure system remains parked over the eastern United
States which, in tandem with the approaching aggregate low-level
cyclonic flow, is facilitating east-southeasterly dry low-level flow.
As a result, the narrow moist sector to our west is becoming, well,
narrower, giving way to lowering humidity levels, rising
temperatures, and generally sunny skies across northern Illinois and
northwestern Indiana. Outside a stray change a thunderstorm manages
to develop near western Winnebago/Ogle/Lee counties this afternoon,
we favor a dry forecast through the rest of the day.
Over the next 12 hours, the central MO MCV is expected to become
dominant and drift eastward into the Ohio River Valley. As a result,
increasing upper-level clouds via anticyclonic convective venting
will spread over the area setting the stage for a muted temperature
drop into the low to mid 60s overnight.
Cloud cover should decrease tomorrow morning as the low pulls away
and stalls near the TN/KY borders. Accordingly, highs tomorrow
should be similar to today and in the mid to upper 80s. The
exception will be along the Lake Michigan shore where cooler
readings will be realized thanks to continued east/northeasterly
onshore flow. A shower or two cannot be ruled out tomorrow south
of a line from Pontiac to Rensselaer closer to the moisture within
the stalled low, but our resident dry airmass may very well prove
too hostile to support updraft longevity and hence, any
precipitation. We`ll continue a dry forecast for this reason.
Tomorrow night looks similarly quiet with overnight lows in the
lower 60s and light winds.
Borchardt
&&
.LONG TERM...
Issued at 204 PM CDT Sun Jun 18 2023
Tuesday through Sunday...
Ensemble models are projecting the short wave trough, that drives
the short-term weather, gradually to move east-southeast on Tuesday
and develop into a closed low before stalling and sitting over the
Alabama/Georgia border. Behind the short wave, a 500-mb ridge will
attempt to grow but the stalled low will prevent it from expanding
eastward forcing it to morph and contort the ridge around the low
from the Texas Panhandle to Western Quebec. Previous runs of longer
range models provided the probability of parts of the CWA reaching
into the low to mid 90s in the middle to later part of this week.
And yet now, with the expected stalling of the upper low, the
cyclonic flow will likely help temper temperatures at the surface
slightly. Low 90s are still in the forecast for Tuesday through
Thursday, but its not as widespread, nor as robust, most likely
areas along a line from Ogle to Ford counties.
As the shortwave cuts off into a low on Tuesday, the pressure
gradient is forecast to tighten slightly over Lake Michigan. Winds
will be projected to mix down and develop stronger northerly
winds over the lake. There is still a lot of uncertainty in how
strong the low gets when it cuts off and where and when exactly
the winds develop on Tuesday. However, stronger winds mean
additional energy being transferred into the waves. The swim risk
forecast was kept at moderate along the Illinois lakefront for now
as it is still over 48 hours away; yet, caution can still be
advised on Tuesday afternoon through Tuesday night. As a reminder
for beachgoers: stay dry when the waves are high.
Rain chances from Tuesday through the rest of the work week are
barren and mostly below 10 percent, which of course does nothing to
help the current drought in the state. Most ensemble models are not
showing degradation of the stalled low over the southeast to happen
until late on Friday, and slowly drift eastward over the weekend.
Some members are showing low weaken and drift northwest ward
slightly as it becomes open wave on Friday, which can bring the
chance for rain back into the area for Friday and Saturday night,
mainly across our southeastern forecast area. But there is so
much uncertainty in how it tracks that the forecast was trimmed
down to just a slight chance (less than 24 percent) for rain and
even thunder, with accumulations being minimal. By late Sunday
into next Monday, there is some signal (especially in the
GFS/GEFS) of the Great Plains ridge developing that can bring more
northwest flow that may translate into some rain chances. But
with it being around Day 7, it is hard to take great stock on that
at this time.
DK
&&
.AVIATION...
For the 00Z TAFs...
No significant aviation concerns through the TAF period.
Early evening surface analysis depicts a weak low pressure trough
west of the Mississippi River, with high pressure to the east
across the eastern Great Lakes. The trough to our west is expected
to weaken and drift southeast into the lower Ohio Valley
overnight, in association with a mid-level disturbance tracking
across Missouri. As this occurs, isolated convection in the
vicinity of the Mississippi River will dissipate this evening
before refocusing well south of the area Monday. While an isolated
shower can`t be completely ruled out near KRFD early this
evening, better chances remain off to the west and potential not
worthy of mention. Otherwise, dry easterly low level flow will
persist, maintaining dry VFR weather across the terminals through
the period.
East to east-southeast winds will diminish with the approach of
sunset this evening, but will maintain a mainly easterly direction
into Monday morning. Daytime mixing and renewed lake breeze
development off Lake Michigan should produce northeast winds 10-15
kts by afternoon. A period of BKN high cloud is expected
overnight, decreasing during the day Monday. Wildfire smoke aloft
will continue to make for a milky/hazy appearance. Near-surface
smoke may produce a few VFR haze obs tonight, though HRRR model
smoke concentration forecasts suggest decreasing low- level smoke
Monday.
Ratzer
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
Visit us at weather.gov/chicago
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/NWSChicago
www.twitter.com/NWSChicago
www.youtube.com/NWSChicago
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1001 PM EDT Sun Jun 18 2023
.SYNOPSIS...
High pressure will build over the area with dry conditions
expected through Monday. By mid next week, a slow moving area
of low pressure may bring a prolonged period of unsettled
conditions.
&&
.NEAR TERM /Overnight/...
As of 10 PM Sun...No changes with late eve update. The few
diurnal showers early have long since dissipated with loss of
diurnal heating.
Prev disc...As of 7 PM Sun...A few showers and an isolated
thunderstorm near the mouth of the Pamlico River formed due to
river/sea breeze convergence, but is now in the dissipating
phase. Therefore, a dry forecast for the rest of the evening and
through the overnight. Still could be some patchy
fog/haze/smoke late tonight, and esp acrs swrn counties, so
areal placement of lowered vsbys still on track.
Prev disc... As of 145 PM Sunday...High pressure continues to
prevail across the area through tonight. Scattered cu across the
area with afternoon heating and have seen a few showers develop
along the sea/river breeze convergence zone adjacent to the
Neuse River. Added isolated showers for this area for the next
few hours but they have not been persisting very long. Hazy
skies across the area as smoke aloft from Canadian wildfires
impacting the area today and have seen some visibility
reductions at times. Added haze to the forecast where HRRR smoke
showing greater concentrations. In addition, smoke from a large
wildfire in Brunswick County has brought air quality issues
across portions of SE NC, including Duplin County where an AQA
continues through midnight.
Skies will become mainly clear this evening with loss of heating
and light southerly winds prevailing. Good radiational cooling
set up and could see patchy light fog as we saw last night but
should burn off quickly after sunrise. Lows will range from the
mid 60s inland to around 70 beaches.
&&
.SHORT TERM /MONDAY/...
As of 200 PM Sunday...The upper ridge axis shifts eastward
Monday as a short wave trough transitions into a vertically
stacked cut-off low over western KY/TN. Moisture will advect
toward the area from the west throughout the day but expect dry
conditions to prevail for the most part, however cannot rule out
an isolated shower moving into western Duplin County late in
the day. Low level thicknesses chance little from today and
expect highs in the upper 80s inland and low to mid 80s coast.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
As of 345 AM Sunday...A quiet start to the week quickly ends as
an unsettled pattern sets up from Tuesday onward across the
Carolinas with multiple rounds of precip possible into next
weekend. With an extended period of rainfall there will be a
threat for some localized flooding across the area though exact
details will need to be hashed out in the coming days.
Tue into next weekend... Upper level low eventually settles into
the the Southeast/Deep South by about mid week and moves little
thru the end on the week with latest guidance suggesting this
upper level low opens up into a trough and shifts NE`wards
sometime next weekend. As this occurs, surface low drops south
towards the Gulf Coast and moves little before lifting
NE`wards next weekend as high pressure ridge centered over the
NE`rn CONUS blocks its progression N`wards this week. With
onshore flow continuing to advect moisture into the Carolinas
continued cloud cover and increasing chances for showers and
maybe some thunderstorms will be possible each day from Tuesday
onward. Latest guidance has shifted the start of the steadier
shower activity slightly earlier to Tuesday afternoon/evening
and has kept at least a chance for showers going into this
weekend. As such have increased PoP`s across the area to high
end Chc to Likely PoP`s through Thurs with SChc to Chc PoP`s
afterwards where confidence is slightly lower. In addition to
this, with PWAT`s increasing to above 1.5 inches by Tue and
then 2+ inches by Wed a threat for moderate to potentially
heavy rainfall will be possible from Tue night thru at least
Thu. This could bring a threat for some localized flooding
across the area but details will need to be hashed out first
before specifics can be mentioned as there is still some slight
uncertainty with regards to location of heaviest precip and
where low eventually ends up. Temps from Tuesday onward will be
below average to average with little diurnal change as highs get
into the 70s to low 80 with lows in the upper 60s to low 70s.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
SHORT TERM /through Monday/...
As of 7 PM Sunday...Pred VFR conditions expected through the
TAF period but hazy conditions as smoke from Brunswick County
and Canadian wildfires has been impacting the area occasionally
reducing vsbys to MVFR. Mainly clear skies and light winds will
allow for good radiational cooling conditions again tonight and
could see patchy fog develop once again late tonight, esp for
wrn TAF sites. Vsbys mainly expected to be MVFR but could drop
to IFR in more favorable locations across southwestern rtes.
Light southerly flow through tonight will become southeasterly
Monday with gusts around 15-20 kt expected during the afternoon.
Dry conditions prevail on Monday with any showers remaining west
of the ENC terminals.
LONG TERM /Monday night through Friday/...
As of 345 AM Sunday... Sub-VFR conditions becoming increasingly
likely from Tue onward as chances for showers and thunderstorms
increase across the FA and moisture advects into the CWA
allowing for ceilings to lower. Winds are forecast to be
southeasterly on Mon but back to an easterly direction by Wed at
around 10-15 kts with gusts near 20 kts possible at times.
These conditions will change little through the end of the
period outside of typical diurnal lowering of winds each night.
&&
.MARINE...
SHORT TERM /through Monday/...
As of 620 AM Sunday...High pressure continues across the waters
through tonight bringing light winds, then lifts northward as a
low pressure system moves into the Tenn River Valley. Southerly
winds less than 15 kt continue through tonight, then become
southeasterly Monday and increase to 10-20 kt in the afternoon.
Seas continue around 2-3 ft through Monday morning, then build
to 3-4 ft in the afternoon with a dominant period around 7 sec.
LONG TERM /Monday Night through Friday/...
As of 345 AM Sunday... Winds will continue to generally remain
E`rly through the period, however they will increase on Tue and
Wed potentially maxing out around 15-20 kts Tue night thru Wed
night as the gradient tightens between the low to our west and
descending ridge to our north. This ridge will eventually push
well offshore later this week allowing gradient to relax and
winds to ease closer to 10-15 kts. Seas mainly 2-3 feet on
Monday increasing to 3-4 feet on Tuesday with Small Craft
conditions likely for the central and northern waters beginning
on Wednesday as seas increase to 4-7 feet. Seas then gradually
lower down to 3-5 ft by Thurs night as winds relax.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...MHX
NEAR TERM...SK/TL
SHORT TERM...SK
LONG TERM...RCF/OJC
AVIATION...TL/RCF
MARINE...SK/RCF
Area Forecast Discussion
National Weather Service Marquette MI
1159 PM EDT Sun Jun 18 2023
.SHORT TERM...(This evening through tonight)
Issued at 323 PM EDT SUN JUN 18 2023
Latest 18z RAP analysis shows deep closed lows across the Pacific
NW and near Newfoundland with a shortwave trough/ridge couplet
across the Midwest. There is a narrow axis of moisture east of the
shortwave trough lifting north across MN today. Recent
satellite/radar imagery shows isolated to scattered
showers/thunderstorms bubbling up near the MS River Valley
associated with deeper moisture. Closer to Michigan, there was a
difficult to explain patch of clouds between Munising and
Manistique this morning near the 500mb ridge axis which kept temps
5-8F cooler and RH ~10% higher until they dissipated early this
afternoon. Farther east, a few sites have dipped below 30% RH but
winds near or below 10 knots kept fire wx concerns in check.
Across the west half, a diurnal cumulus field developed indicating
a well-mixed boundary layer where temps are around 80F and dew
points mainly in the mid to lower 50s. A lake breeze has developed
along the immediate Lake Superior shoreline, but decent southerly
flow has prevented the boundary from pushing inland.
Looking ahead to tonight, the shortwave/vort max over MN this
afternoon appears to get sheared apart across far western Lake
Superior. Weakening synoptic scale ascent combined with a reasonably
well-mixed and dry boundary layer should prevent any measurable
precip. It`s tough to find any CAPE so thunder chances were removed,
but I suppose a brief sprinkle/rain shower can`t be ruled out late
tonight across Gogebic/Ontonagon Counties. Increasing cloud cover
combined with better low level mixing should keep temperatures
several degrees warmer than last night across interior locations.
While most places should cool into the 50s, the far west could
stay in the low 60s.
.LONG TERM...(Monday night through Sunday)
Issued at 412 PM EDT SUN JUN 18 2023
Weak ridging over the Upper Great Lakes will become amplified by
midweek as a rex block takes shape over the east half of the CONUS.
Anomalously strong ridging by midweek with this pattern will result
in continued dry weather and a trend toward very warm to hot
conditions for the mid to late week period. Relief from the hot and
dry weather could potentially come sometime next weekend as the rex
block breaks down over the eastern CONUS and shortwaves moving over
the flattened mid-upper level ridge bring chances for convection.
Beginning Monday, convection from a decaying MCV currently over
southern/central MN could sneak into the western fcst area tonight
and linger into Monday, although I doubt this would amount to
anything more than isolated showers based on fcst soundings. Inland
max temps Monday under partly cloudy skies will rise into the lower
to mid 80s with readings near the Great Lakes shores mostly in the
mid to upper 70s. Min RHs could dip blo 30 percent over the eastern
interior but fairly light sse winds around 10 mph should
somewhat mitigate fire wx concerns.
Increasingly amplified ridging by midweek will continue the dry
weather for the majority of the week. At the same time, the airmass
overhead looks to support 850mb temps between 15-19C range with 5H
heights exceeding 590 dam. This should yield daytime highs over the
interior well into the 80s and probably into the lower 90s
throughout the extended. The warmest days look to be Tuesday
through Thursday. Prevailing southerly flow off Lake Michigan
could keep eastern counties from getting too hot and should keep
locations along the shore in the upper 70s to lower 80s. Forecast
temps will be trickier along the Lake Superior shore as the
prevailing southerly flow may be strong enough to suppress lake
breezes there and a downsloping flow could end up keeping temps
warmer instead of cooler. Diurnal mixing should support min RH
values falling into the 30-40% range or lower each afternoon.
Fortunately, winds should not be overly strong under the ridge,
and there should be a good potential for lake breezes each day.
By late week, and particularly the weekend, the ridge shifts east
and several shortwaves move across the Upper Great Lakes pushing a
cold frontal boundary into the area. This boundary will increase the
chances for showers/t-storms by the weekend and could provide some
relief from the heat.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1158 PM EDT SUN JUN 18 2023
VFR will remain the predominant flight category for the duration of
the TAF period at all TAF sites despite increasing cloud cover at
IWD and CMX due to a weakening disturbance to the south. In
addition, rain showers in association with that disturbance will
drift through IWD early this morning. A couple rumbles of thunder
cannot be ruled out with those rain showers, but environment is not
favorable for convective development. Winds will be light out of the
southeast.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 412 PM EDT SUN JUN 18 2023
Recent guidance continues to suggest ridging will dominate the
region through a majority of next week. There is a chance a decaying
thunderstorm cluster could move into western Lake Superior this
afternoon/evening, but otherwise, dry conditions with light winds
are expected. Higher reporting platforms may observe some higher
winds here and there, but stable conditions should keep winds light
and waves minimal near the surface.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...EK
LONG TERM...Voss
AVIATION...TDUD
MARINE...Voss
Area Forecast Discussion
National Weather Service New York NY
1028 PM EDT Sun Jun 18 2023
.SYNOPSIS...
Low pressure will continue moving northeastward across the
Canadian Maritimes through tonight. A weak cold front moves
through this evening and then east of the region later tonight.
Another weak front moves into the area Monday into Monday
night. This surface trough lingers nearby Tuesday as high
pressure builds south from New England. The high moves overhead
Wednesday, before shifting offshore into late week. Low pressure
to the south may impact the area this coming weekend.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Update the forecast to include isolated showers over eastern LI
and SE CT for the next few hours. A few showers are developing
off a decaying sea breeze over LI Sound and are pushing through
eastern Suffolk County. Additional showers are expected to shift
through SE CT. A cold front should shift winds to NE overnight,
but will remain light.
Dry conditions otherwise expected overnight with more
subsidence taking place aloft. Temperatures will remain near
normal for lows late tonight. Forecast lows tonight are mainly
in the mid 50s to mid 60s. Lows get into the lower 50s for some
interior locations and possibly for some parts of the Pine
Barrens as well while some parts of NYC will have lows more in
the upper 60s for tonight.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
The local area will still be under the upper level trough with
periodic shortwaves moving along the southern end of the trough.
One moves through Monday night. The trough and shortwaves will
still be present despite some slight height rises. There will
not be much strength to the shortwave but enough to warrant the
mention of the possibility of rain showers Monday afternoon
through Monday night. Models also indicate that low level
instability will be a little higher than the previous day so
added in a slight chance of thunderstorms across the most
interior parts of the area within the Lower Hudson Valley into
Southwest CT.
At the surface, weak high pressure to the north and east allows
for an easterly flow to develop. The forecast models also
depict some trough development across the interior that could
further focus convergence and allow for rain shower development
late in the afternoon and into Monday night. The trough remains
in the vicinity of the region Monday night. The easterly flow
will be greater along the coast and less inland, allowing for
relatively warmer temperatures across the interior with greater
convergence as well. The easterly flow slightly weakens Monday
night.
Temperatures Monday trend slightly cooler along the coast
compared to the previous day with more maritime influence but
will be nearly the same inland compared to the previous day.
Used NBM and a consensus of MOS for the forecast highs. For
Monday night, used a blend of consensus raw model temperatures
and NBM to convey a less vast range of lows, generally in the
upper 50s to lower 60s, a little below normal for this time of
year. The airmass will be transitioning to more of a cooler
maritime airmass.
The area where showers will be more probable is where the HRRR
was showing some increase in near surface smoke for Monday
afternoon into Monday evening. Because of the increased chances
for showers, do not think concentrations of smoke would be much
considering the wet deposition from the rain showers.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Troughing over New England finally exits as ridging over the Upper
Great Lakes builds and gradually shifts east this week.
A surface trough lingers nearby to start the period, with a weak
shortwave passing through New England providing some additional
energy. This weak forcing and instability (MUCAPE values around 500
J/kg) may support the development of a few scattered showers or
thunderstorms across the interior in the afternoon, though most
should remain dry.
Upper ridging begins to shift east Wednesday into Thursday as
surface high pressure tracks south into the region, maintaining dry
conditions. With the east to southeast flow, a relatively cool air
mass will be across the region through Thursday; highs mostly in the
70s. The ridge and surface high move offshore into the start of the
coming weekend, with a return flow allowing temperatures to return
to more seasonable levels, with humidity also on the increase.
Guidance continues to keep low pressure to the south late this week,
though rain chances begin to climb this weekend with increasing
moisture on the S/SW flow. Capped PoPs at high chance (50%) given
inherent uncertainty at this stage. Otherwise, with subtle
adjustment, national blended guidance was followed for this
update.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
A weak backdoor cold front pushes through the area overnight,
otherwise, weak high pressure will be in place.
VFR.
Light winds ahead of the cold front, which will be shifting wind
to NE overnight, but remaining light.
For Monday, NE winds less than 10 kt for morning push, giving
way to hybrid SE sea breeze late morning into early afternoon,
pushing through all terminals except KSWF.
Haze aloft possible from Canadian wildfires Monday morning, no
issues anticipated at ground level.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No unscheduled amendments expected.
OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY...
Mon Night - Tue Night: VFR. A chance of showers with isolated
thunderstorms, well north and west of the NYC/NJ terminals. E
winds 10 kt or less. Chance of MVFR/IFR cigs Mon Night/Tue AM
and Tue Night/Wed AM.
Wed - Fri: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
The pressure gradient across the forecast waters will remain
relatively weak through Monday night, allowing for sub-SCA
conditions to continue.
With high pressure dominating Tuesday into late in the week, winds
and seas are expected to remain below SCA levels across the forecast
waters.
&&
.HYDROLOGY...
Any rain showers into Monday night are not expected to result
in any hydrologic impacts. Rainfall amounts are expected to
remain less than a quarter of an inch on average.
No hydrologic impacts are expected through the end of next
week.
&&
.TIDES/COASTAL FLOODING...
There is a low risk of rip currents Monday for all Atlantic facing
beaches with 2 ft waves and 7 second or less dominant periods
expected.
There is a moderate risk of rip currents on Tuesday for all Atlantic
facing beaches with 2-3 ft waves and 7 to 8 second dominant periods
expected.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JM/DR
NEAR TERM...JC/JM
SHORT TERM...JM
LONG TERM...DR
AVIATION...JC
MARINE...JM/DR
HYDROLOGY...JM/DR
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Shreveport LA
938 PM CDT Sun Jun 18 2023
...New UPDATE...
.UPDATE...
Issued at 926 PM CDT Sun Jun 18 2023
Severe Thunderstorm Watch #336 remains in effect until 1 AM for
Union County Arkansas as well as all of Northern Louisiana. Storms
should continue to show a weakening trend over the next couple
hours such that parishes in the watch (at least the western
parishes across Northern Louisiana) may be cancelled early.
Convection this far this evening remains across portions of North
Central and Northeast Louisiana where frontal forcing is a little
more concentrated. Deep Layer shear is a little stronger as well
which in the reasoning for better storm organization. Taking a
look outside our office, moderate cumulus towers can be seen,
struggling to make much height further west along the boundary
across northern Caddo, Bossier and Webster Parishes. Will continue
to watch the progression of the storms across Claiborne and Union
Parishes however before canceling the watch early near and to the
west of the I-49 Corridor. Did however lower pops along and ahead
of the slow moving boundary with latest HRRR and NAM output
suggesting that renewed convection with be isolated at best as the
boundary approaches and sinks south of the I-20 Corridor much
later tonight.
Hourly fcst temps are in the ballpark so no changes were made to
the current forecast temperature wise.
13
&&
.SHORT TERM...
(This evening through Monday Night)
Issued at 259 PM CDT Sun Jun 18 2023
Latest radar loops shows a weak frontal boundary drifting north and
northeast across East Texas and Louisiana. Most of the eastern
half of our CWA have seen little in the way of cloud cover today,
but this area has also been largely overturned by the earlier
convection. South of the frontal boundary, the atmosphere is
extremely unstable. Latest mesoanalysis indicates surface-based
CAPE in excess of 5000-6500 J/kg. With the boundary drifting
northward, this unstable atmosphere should also advect north back
into the CWA over the next few hours. The development of
convection is highly uncertain, and the models are having
difficulty resolving any lingering effects from this morning`s
storms. If another round of thunderstorms develop late this
afternoon and into this evening, the most favored area will
generally be southeast of a line from Jacksonville TX, to
Shreveport, to El Dorado AR. The extreme instability combined
with very strong deep layer shear will support a threat for very
large hail (2 inches in diameter or greater), damaging winds, and
possibly a tornado. I`ve generally favored the HRRR since it has
performed reasonably well over the last couple of days. The severe
weather threat should quickly end shortly after midnight as the
storms dissipate and exit the area.
This persistent threat for severe weather should finally come to
an end early Monday. There is still a chance for isolated to
widely scattered convection late Monday and into early Tuesday as
an upper trough becomes cutoff over the Southeast CONUS, but the
risk for severe weather appears low, and convective coverage
should be rather spotty. The big story will be the dangerously hot
and humid conditions, which won`t abate for a few more days (more
on that below). Peak heat index values above 110 degrees F are
once again expected across Central Louisiana and much of East
Texas, so another Excessive Heat Warning was issued for Monday. In
addition, a Heat Advisory was issued just north of the warning,
where peak heat indices will likely be between 105 and 109 degrees
F.
CN
&&
.LONG TERM...
(Tuesday through next Saturday)
Issued at 259 PM CDT Sun Jun 18 2023
Beginning Tuesday morning, a pronounced upper level high over
southwestern Texas and the Rio Grande valley and its associated
ridging will build north and east enough to keep the heat locked in
place for the ArkLaTex for the remainder of the week and likely into
next weekend. Highs in the 90s are to be expected throughout the
week for much of the region, ranging on Tuesday from the lower 90s
north to mid to upper 90s south. Coupled with dewpoints in the mid
70s across the region, the need for continued extensions of the Heat
Advisory and possibly Excessive Heat Warning will need to be
explored. Overnight lows will hold reasonably steady in the low to
mid 70s with perhaps a few upper 60s returning in our northeastern
regions across Arkansas late in the week.
Through the course of the week, northerly flow aloft, encouraged by
the ridge to our west and the closed low to our east over Alabama
and Georgia may allow the development of some more seasonal
summertime afternoon convection. Tuesday morning looks to find our
northeastern zones still holding on to showers and storms from
overnight, which rebuild later in the day with a renewed impulse of
energy on the west side of the aforementioned closed low. This
activity looks to dissipate by midnight Wednesday, commencing a more
recognizable June pattern of dry nights and mornings with a spot of
afternoon convection possible, particularly across our southern and
easternmost zones.
Because the closed low retrogrades north and west over the Ohio and
middle Mississippi valleys late this week, reestablishing
northwesterly flow aloft in the process, Friday looks to be a touch
more active, with storms across the southeastern half of the area by
early afternoon. The low will lift north and east over the Great
Lakes region into next weekend, allowing the Texas ridge to build
east as it departs, returning the ArkLaTex to an afternoon
convection pattern, accompanied by another heat wave.
Wednesday and Thursday look to see an incremental relief from this
hot pattern, with more lower 90s than mid to upper 90s across the
ArkLaTex. These higher values will begin to return Friday, and only
skyrocket from there into next weekend, which at this point looks to
consist of upper 90s for highs, accompanied by lows in the upper 70s
for the majority of the region. At this long range, some ebb and
flow in the precise values is to be expected, but the entire Four
State Region should be prepared for this warm pattern to hold on for
the course of this forecast period.
/26/
&&
.AVIATION...
(00Z TAFS)
Issued at 452 PM CDT Sun Jun 18 2023
Tricky aviation forecast for the evening and a portion of the
overnight hours as we may be dealing with convection near or south
of our I-20 terminals in the 00z-08z timeframe. The favored
location of this convection would be along a weak frontal boundary
which is currently located near the I-30 Corridor of NE TX but
then snakes its way southeast into Central Louisiana. The
Louisiana portion of this boundary is supposed to retreat
northward towards the I-20 Corridor while the NE TX portion of the
boundary will remain stationary until later this evening when it
will begin to take on a southeastward push towards the I-20
Corridor. All this to say we are more confident with VCTS and
TEMPO TSRA at the LFK and MLU terminals than the I-20 terminals
this evening into the overnight hours. Did however mention VCTS
along the I-20 terminals through 06z just in case and will handle
any TSRA with AMDs if necessary.
Winds will be mostly variable giving the waffling of the boundary
across our airspace through the TAF period. Any MVFR ceiling or
lower in association with convection should return to VFR
conditions on Monday outside some patchy morning fog.
13
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 74 96 76 93 / 20 10 20 10
MLU 72 94 73 90 / 40 10 20 20
DEQ 65 94 70 92 / 0 0 20 10
TXK 70 96 73 94 / 10 0 20 10
ELD 68 93 70 90 / 10 0 20 10
TYR 74 98 78 97 / 10 10 10 0
GGG 72 96 76 95 / 10 10 20 10
LFK 76 99 77 97 / 20 10 10 10
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...Heat Advisory from 10 AM to 8 PM CDT Monday for LAZ001>003-
010>013.
Excessive Heat Warning from 10 AM to 8 PM CDT Monday for
LAZ017>020-022.
OK...None.
TX...Heat Advisory from 10 AM to 8 PM CDT Monday for TXZ108>112-125-
126-138.
Excessive Heat Warning from 10 AM to 8 PM CDT Monday for TXZ124-
136-137-149>153-165>167.
&&
$$
SHORT TERM...09
LONG TERM....26
AVIATION...13