Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/29/20
Area Forecast Discussion
National Weather Service Birmingham AL
639 PM CDT Thu May 28 2020
For 00Z Aviation.
/Updated at 0501 PM CDT Thu May 28 2020/
Not overly impressed by the appearance of the radar or satellite
depictions late this afternoon. An are of showers and
thunderstorms was located across western Tennessee, southward
along the Alabama Mississippi state line, then to Tuscaloosa and
Demopolis. The convection was moving generally northeast around 35
mph. The NAM12, HRRR and a few other CAMS`s indicated the highest
rain chances northwest. Localized higher mean moisture and lift
associated with upper level perturbation moving through the flow
located along the I-59 corridor. Much of the cumulus field looks
less than impressive and even see a few gravity waves moving into
convection over Marion County. SBCAPE values are only 1500-2000
with MLCAPE only 1000. Mid level lapse rates are poor today but
lower level lapse rates are finally improving due to heating. CAPE
hail parameters are marginal around 500 and precip water values
1.5 or less. Will maintain a small chance of some gusty winds and
small hail but bump it northward near the lift, generally along
and north of I-59. There is an outside shot at a severe storm, but
it will be very limited. The timing was also adjusted as the
feature should clear the west by 7 pm and potentially linger until
10 pm far northeast.
Previous short-term discussion:
/Updated at 128 PM CDT Thu May 28 2020/
This afternoon through Friday.
The persistent closed upper low remains over Western Arkansas
this morning. A disturbance over Southeast Arkansas is supporting
showers and thunderstorms over Northwest Mississippi. This
activity is expected to continue moving northeast, efficient
portions of our northwest counties this afternoon and evening.
Some of the storms which may become strong to severe due to
increasing low-level instability along with drier air aloft which
is contributing to higher downdraft convective available potential
energy values in addition to higher bulk shear values.
The strongest storms will be capable of producing large hail and
damaging winds. Frequent lightning and torrential downpours are
also expected. Localized flooding remains a possibility in low-
lying and poor drainage areas, especially if they experience
multiple storms over a short time frame.
Expect highs in the mid 80s north and east to readings closer to
90 south and west. Winds will be out of the southwest 5-10 mph
outside of convection.
Expect the upper low to open into a trough and begin ejecting
northeast into the Ohio River Valley region this evening and
overnight as a shortwave dives southeast out of the High Plains
region. Across our area, ongoing shower and thunderstorm activity
will move northeast with time and is expected to gradually wane in
intensity later this evening and overnight. Clouds will persist
with some reductions in visibility tonight with patchy fog
possible, especially in areas that get decent rains today. Lows
will range from the low 60s north to the upper 60s far southeast.
Winds will become light and remain out of the south outside of
Friday will bring morning clouds followed by increasing chances
again for showers and storms. No organized strong or severe storms
are expected as the upper trough will be pulling away with less
dynamics to work with. Highs will the in the mid 80s with winds
becoming out of the west 5-10 mph.
/Updated at 0316 AM CDT Thu May 28 2020/
Saturday through Thursday.
The stubborn upper level low will finally get kicked out of the area
by Saturday and the trailing precipitation should will come to an
end by the late afternoon, with generally dry conditions Saturday
night. Upper level ridging will build into the area on Sunday and
Monday behind a cool front that will work through on Sunday from the
north. Very limited moisture will be associated with this system so
stayed with a dry forecast. Central Alabama will remain on the
western side of the upper level ridging through the rest of the
forecast so synoptically we should remain on the drier side. With
that said if the ridge remains further east or south then rain
chances would have the potential to increase during the second half
of the week, especially in the west. Of course we will continue to
evaluate daily for those hit and miss summertime airmass storms that
are really not hinted at until the mesoscale models begin to be
incorporated into the forecast. Look for highs to slowly warm over
the weekend into the middle to upper 80s with much of the next week
in the upper 80s to low 90s.
00Z TAF Discussion.
A broad upper trof near the MS River will produce sct shwrs and
tstms across central Alabama, mainly after 15z. A cluster of
tstms currently over nw Alabama will likely stay north of I-20. A
few showers or storms may develop farther south, but chances too
low to include at any TAF site. Despite proximity of upper trof,
the low levels will remain relatively dry, and this will limit
areal coverage of convection as the trof pushes slowly eastward.
Expect sct shwrs to develop after 12z, with tstm activity increasing
in the afternoon hours on Friday. The drier low level air mass
mentioned above will also hinder cloud formation, with cigs
staying above 3000 feet agl at most sites. Higher moisture
content in the low levels across southeast Alabama will result in
areas of fog and IFR cigs at KTOI from 10z thru 13z.
Moisture remains elevated through the end of the week with higher
chances of wetting rains including thunderstorms through Friday.
A few strong to severe storms will be possible this afternoon and
evening across Northern and Western Central Alabama. Patchy fog
will again be possible Friday morning. Minimum relative humidity
values are forecast to remain above 50 percent through Friday. On
Saturday, a surface front may bring a few showers and storms but
then some drier weather and lower humidity values are expected for
the second half of the weekend and into the first part of next
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 62 84 61 82 56 / 40 50 20 10 0
Anniston 66 85 62 83 57 / 40 50 20 10 0
Birmingham 66 85 64 84 59 / 50 40 20 10 0
Tuscaloosa 65 86 64 84 59 / 50 40 10 0 0
Calera 66 85 64 83 59 / 40 40 20 10 0
Auburn 67 84 64 82 61 / 20 50 30 20 0
Montgomery 69 86 65 85 61 / 20 50 20 10 0
Troy 68 86 66 85 62 / 20 60 30 30 0
Area Forecast Discussion
National Weather Service State College PA
1134 PM EDT Thu May 28 2020
Tropical moisture will cover PA into Friday night. A strong
cold front will push through the state Friday evening and
night, bringing numerous showers and scattered strong to
potentially severe thunderstorms. Much cooler and less humid
conditions will follow for the weekend into early next week as
the flow turns decidedly northwest at all levels of the
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Compact area of heavy showers and a few TSRA continues to
linger/train over portions of the Central Mtns of PA and Susq`s
West Branch this evening.
Latest HRRR run shows this area of convection slowly waning over
and lifting NE over the next few hours, leaving us with a
variably cloudy and muggy night with a light south to southeast
breeze and sfc dewpoints in the 60s...to near 70F in the Susq
Valley. Low temps won`t be too much higher than these dewpoints.
Additional isolated to scattered showers should redevelop
across the region late tonight into the mid morning hours of
Friday as the nose of an 80-90 kt 300 mb jet max over eastern KY
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
Friday could be the severe weather event we usually see on the
31st of May. However, the hodograph isn`t as potent as it could
be for tornadoes. Moisture is super high and the pre-frontal
trough coming through at or just before peak heating will likely
be the focus for strong and severe storms. SPC has expanded the
coverage of the SLGT risk to cover most of CTP CWA. There is a
good chance of a second line of storms as the front moves closer
and starts to cross the CWA from NW-SE in the early evening. The
convergence along that line is suspect, but the air will not be
worked-over/stabilized as the front nears. The front should
clear things out early in the night over the NW and by sunrise
in the SE. The bulk of the TSRA should be over by 1-2AM, though
after loss of sun and best convergence. Maxes will get into the
80s in the valleys and u70s in the higher elevs. Dry air moving
in Fri night should allow temps to get into the 50s in the NW
half of the area.
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Some scattered convection could linger into Sat over the SE,
with a few light showers possible over the NW as well as the
upper trough slips overhead. Drier conditions are expected for
later Saturday into Monday. Early next week, models are in good
agreement on an extended period of NW flow as a large scale
upper trough sharpens over SE Canada and the Eastern US. An
expansive sfc high pressure builds back in across the Ohio
Valley and drifts just south of PA by Tue and then offshore by
the middle of the week. Expect mainly dry weather and cooler
less humid conditions Mon-Tue (including a couple of chilly
mornings, though some cirrus overhead may keep mins from
bottoming out in the 30s over the northern mountains).
Quick hitting shortwave trough slides through on Tue and may
produce some scattered light showers. The longwave trough
flattens a bit briefly before sharpening again as large ridge
builds over central parts of the country. This will allow
another weak shortwave or two to ripple by overhead on Thu which
will interact with a leftover weak surface boundary (from Wed)
to keep mention of showers in the forecast.
The first half of next weekend is looking pleasant and dry.
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
Most of the showers and storms out of the area now. Still a
storm near IPT until around Midnight.
A few more showers lifting northward toward AOO and JST, but
these are weakening. Thus went with a TEMPO group at AOO and JST.
Some other adjustments to the TAFS late this evening.
Earlier discussion below.
00Z TAFS sent.
Developing line of showers and isolated thunderstorms on western
edge of lower dewpoints. Tropcial moisture to the east, but time
of day should keep the storms from being too strong. Main issue
will be torrential rain and wind gust, mainly up to 35 to 40
mph, but isolated higher gust possible.
Lower clouds and some fog later, once skies clear back out.
For late Friday morning into the afternoon hours, went with VFR
conditions again, and VCSH. Potential for thunderstorms, but
with the cold front well to the west, and lower dewpoints than
today, just went with VCSH for now.
Improving conditions for the weekend, into at least early next
Tuesday, as much cooler and drier air works southeast into the
Fri night...CFROPA. SHRA/TSRA ending W-E.
Sat...MVFR cigs poss NW, otherwise no sig wx..
Sun-Mon...AM Fog poss N. Otherwise VFR.
Tues...chc SHRA/MVFR, mainly NW.
Area Forecast Discussion
National Weather Service Cheyenne WY
825 PM MDT Thu May 28 2020
Issued at 812 PM MDT Thu May 28 2020
Did a quick update to the forecast package for the overnight
hours. Lowered the temps a degree or two across the Panhandle to
match up better on our CWA borders with the LBF and BOU offices.
Current NBM guidance appeared to be 2-3 degrees warmer and was a
glaring opportunity to rectify while taking a look at projected
lows for that area. Warmest overnight lows still look to be in the
lower elevations along the North Platte River Valley in the NE
Panhandle region. One thing to take note of is that short term
guidance continues to hint at east/southeast/south winds overnight
in SE WY, east of the Laramie Range. Monitoring the decreasing
ceilings heights overnight will be recommended to the night shift
in the event that patchy fog or low visibility occurs. Current
HRRR guidance is only hinting at the Summit region potentially
having low ceilings/visibility, but wouldn`t be surprised if it
spreads further east to encompass the city of Cheyenne if
widespread low ceilings and patchy fog occurs.
.SHORT TERM...(Tonight - Friday)
Issued at 202 PM MDT Thu May 28 2020
A few thunderstorms will be possible late this afternoon and early
evening, mainly over and in the general vicinity of the S. Laramie
Range where differential heating this afternoon has reinforced the
weak surface boundary draped across this area. SPC Mesoanalysis is
indicating upwards of 40 knots of deep layer vertical shear, along
with 1000 J/kg SBCAPEs where full sun has occurred today. A couple
of stronger storms are certainly possible with hail and gusty wind
the primary hazards, but overall forcing is quite weak with modest
upslope flow and limited low-level convergence. As such, we`re not
expecting to see anything widespread but the ongoing SPC MRGL risk
is in good shape. Any activity should diminish after sunset.
Upper-level ridging remains in control Friday w/ the CWA remaining
on the northern periphery of the 4 Corners High. There is a chance
that weak disturbances riding along the edge of the ridge could be
foci for convective development on Friday, but in general we would
expect the better chances for showers & thunderstorms to be placed
to the north within stronger NW flow aloft. There is some question
regarding vertical shear strength, but 35 knots of 500 mb flow may
be sufficient for organized storms. The latest NAM Nest is showing
potential for dew points in the 50s & resulting CAPEs over 2000 J/
kg. Any storms that do develop could be strong to severe, but once
again it should be rather isolated.
.LONG TERM...(Friday night - Thursday)
Issued at 225 AM MDT Thu May 28 2020
Daily chances for showers and thunderstorms expected this week as
daytime high temperatures rise under the influence of a stubborn
upper level ridge, called an omega block, builds aloft. Surface
moisture will be pulled north under the ridge axis, though severe
potential looks limited by a lack of shear and capping aloft
beginning Saturday. This will be the story for the weekend and
into next week as the ridge stubbornly sits aloft and surface
temperatures increase into the 90s east of the Laramie Range by
MOnday. Some model discretion by mid-neat week with how quickly
this ridge will transition east, and how much moisture will be
pulled north under the ridge for widespread storm potential.
Either way, the region may be stuck under this warm, rather dry
pattern for the foreseeable future.
.AVIATION...(For the 00Z TAFS through Friday afternoon)
Issued at 445 PM MDT Thu May 28 2020
Showers and thunderstorms struggling to develop this evening across
southeast Wyoming, so started removing VCSH from the KLAR and KCYS
TAF. Low to midlevel clouds are 4000 to 6000 feet AGL will continue
through 12z with some locally lower CIGS around KCYS and KLAR.
HAZARDS/WEATHER TRENDS: Can not rule out a quick shower or thunder
shower over the southeast Wyoming terminals this evening, but
confidence is lower compared to 6 hours ago. Otherwise, VFR
conditions expected today with some lower CIGS around 1000 feet AGL
near KCYS and KLAR by 12z Friday.
Issued at 225 AM MDT Thu May 28 2020
Scattered showers and isolated thunderstorms expected this
afternoon, with gusty winds the primary threat. This may also be
the case tomorrow as a ridge of high pressure builds over the
Great Basin and transitions east over the High Plains. Will see
afternoon humidity drop into the teens from west to east,
beginning in Carbon County Saturday, and spreading east into the
High Plains by Monday. These humidities will pair with increasing
high temperatures, reaching into the 90s by next week. Daily
afternoon thunderstorm potential will pose a threat as chance of
wetting rains remains low for the period. This is a perfect setup
for elevated to locally critical fire weather conditions.
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
651 PM CDT Thu May 28 2020
.UPDATE.../WATCH TO CONTINUE FOR A SHORT WHILE LONGER/
For practical purposes, the threat for severe wx has been much
reduced for South Central TX. However, as NW flow events can be quite
tricky, as noted in the severe storms approaching Bell County, will
wait another 30-45 minute before clearing counties from the SVR
A few storms warrant a VCTS around DRT for another hour or two. All
other activity is reduced to mostly some residual sprinkles, assuming
the cluster of Central TX storms pass well to the north of AUS. By
late this evening we should see minimal cigs and mostly light to
moderate north winds.
.PREV DISCUSSION... /ISSUED 231 PM CDT Thu May 28 2020/
The Storm Prediction Center has issued a Severe Thunderstorm watch
for generally areas along and west of HWY 281, in addition to Hays,
Guadalupe, and Wilson Counties. This includes the San Antonio and Del
Rio metro areas. The watch runs through 10 pm tonight and highlights
the threat for hail up to 2 inches and 70 mph winds.
PREV DISCUSSION... /ISSUED 211 PM CDT Thu May 28 2020/
SHORT TERM (Tonight through Friday Night)...
After yesterday`s severe weather event that left large swaths of
quarter sized hail or greater, several hail reports between 2-2.75
inches, and gusty winds in several spots it looks like there will be
one more round of strong to severe storms this evening before
quieter weather prevails tomorrow into the weekend.
With the pesky upper level low to the northeast of Texas, over the
Oklahoma/Arkansas border, it leaves South Central Texas in a
northwest flow pattern. Despite several rounds of storms over the
last few days southeasterly winds at the surface continue to allow
for plentiful moisture return between the rounds. Couple this with
lift associated with daytime heating and a boundary moving in from
the north, instability of between 2000-3000 j/KG, and just enough
shear to help the storms maintain the strength and you get the
recipe for the strong to severe storms today. Convective initiation
is already ongoing across San Angelo`s area from San Angelo south to
Junction. This is earlier than really any of the convective allowing
models showed CI ongoing today. Several severe thunderstorm
warnings have already been issued for this activity.
The spread of the morning high resolution models really resolved
into 3 camps: 1) some (like the Texas Tech WRF) developed storms
into a complex that could dive to the southeast and impact areas
from San Antonio to Austin, 2) others (like many members of the 12z
SPC HREF) developed storms to the north of our area and took them
generally south through the Edwards Plateau along and west of HWY
281, 3) Lastly the HRRR has trended drier for most of its runs since
12z with only isolated storms through the evening. Just using
current radar trends with the activity over SJT`s CWA the 2nd
scenario seems most likely. Outflows are driving the storms more to
the south and are kicking off additional storms. The 1st scenario
does remain feasible as the storms could come together developing a
cold pool, and drive to the southeast. The 12z/16z SPC updates take
this scenario into account as they extended the slight risk eastward
from just across the Rio Grande Plains to a Kerrville to San Antonio
to Cuero line. Trends will have to be monitored through the
afternoon, but still think that the best chances for storms will be
along and west of the HWY 281 corridor through the evening. An MCD
just issued by SPC highlights the risk of rapid updraft
intensification due to the steep lapse rates which would mainly lead
to a hail threat in the short term. If/when these storms grow
upscale and develop that cold pool and become a complex of storms
damaging thunderstorm winds would become the main concern.
All of this is occurring within the northwest flow aloft along the
leading edge of a weak front. Models show a distinct northerly wind
shift with drier and slightly cooler air working south later this
evening into the overnight behind the storms. This along with the
upper level ridge building in from the west as the upper low exits
tomorrow will squash any further rain chances and lead to a drying
trend for Friday into much of next week. With the drier air in place
afternoon highs should only climb into the mid to upper 80s to lower
90s for Friday and Saturday. This is very close to normal for this
time of the year. Looking back at the months of April and May our
County Warning Area was under a Marginal, Slight, or Enhanced risk
of severe storms from SPC over 50 percent of the days. As I said in
the morning update AFD I think most folks in South Central Texas
will welcome the quieter weather pattern and seasonable temperatures
through the middle of next week. Whether it has been the busy
emergency managers and local TV/private/NWS meteorologists or those
who have been impacted by the hail/wind/tornadoes over the last few
weeks it will give us all time to take a breath and enjoy the quiet
LONG TERM (Saturday through Thursday)...
Fairly quiet weather pattern will be in place to start the long term
with an omega block setting up over the CONUS. An upper level ridge
will build over the middle of the US and a large upper level trough
over the Pacific and another over the Northeast US. The only feature
preventing a true omega block pattern setting up will be an inverted
trough that global models keep over Mexico and southern TX late this
weekend. The feature will slowly advect northward and push some
energy up into South-Central TX by early next week. Only have slight
chances for showers and storms in the forecast for Monday into
Tuesday for this.
Apart from this, a benign pattern will remain in place with high
temperatures running close to climatological normals and little to
no chance for rain. A much needed break from the active weather the
region has had over the last couple of weeks.
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 68 87 65 87 66 / 20 0 0 0 0
Austin Bergstrom Intl Airport 67 86 64 87 64 / 20 0 0 0 0
New Braunfels Muni Airport 68 87 64 88 64 / 30 0 0 0 0
Burnet Muni Airport 64 85 62 86 63 / 10 0 0 0 0
Del Rio Intl Airport 70 92 67 93 68 / 40 - 0 0 0
Georgetown Muni Airport 65 86 62 87 64 / 10 0 0 0 0
Hondo Muni Airport 68 90 64 92 66 / 30 - 0 0 0
San Marcos Muni Airport 67 86 64 88 64 / 20 0 0 0 0
La Grange - Fayette Regional 69 86 65 88 65 / 20 10 0 0 0
San Antonio Intl Airport 69 88 66 90 67 / 30 0 0 0 0
Stinson Muni Airport 70 89 67 90 68 / 30 - 0 0 0
Area Forecast Discussion
National Weather Service Goodland KS
459 PM MDT Thu May 28 2020
.SHORT TERM...(This evening through Friday night)
Issued at 245 PM MDT Thu May 28 2020
This Afternoon: Though no obvious surface boundaries and/or upper
forcing can be identified in Southwest Nebraska early this
afternoon -- agitated Cu are evident in visible satellite imagery
over Dundy/Chase counties -- presumably in association with weak
low-level convergence amidst a marginally unstable, uncapped
airmass (mid-level lapse rates ~5.5 C/km). HRRR simulated
reflectivity forecasts suggest that an isolated updraft will
develop invof Dundy/Hitchcock counties ~22-23Z and progress SSE to
near Colby/Oakley by 01-02Z prior to dissipating with loss of
heating. With weak forcing, weak mid-level lapse rates, weak
mlcape (250-500 J/kg), modest dcape (700-800 J/kg), and 20-30 kt
effective deep layer shear.. severe weather is not anticipated.
This Evening-Tonight: N-NNW flow aloft will prevail over the
region -- on the NE periphery of an amplifying upper level ridge
over the Desert Southwest/Intermountain West. Simulated
reflectivity forecasts via the HRRR and NAM NEST suggest that
scattered showers (perhaps an isolated storm) will develop in NE
Colorado late this evening, and that light showers may persist
into portions of far NW Kansas overnight. Aside from an
increasingly upslope component to low-level flow and the onset of
weak warm advection late tonight -- little in the way of
additional forcing can currently be identified. Regardless, no
impactful weather is anticipated.
Fri-Fri night: A broad surface trough will develop in the lee of
the Central/Southern Rockies on Fri -- as the amplifying upper
ridge over the Desert Southwest builds northward into the
4-Corners -- and flow aloft backs from NNW to NW over the High
Plains. With NW flow aloft and southerly low-level flow on the
eastern periphery of a developing lee trough, isolated convection
cannot be ruled out in Colorado and adjacent KS border counties
during the late afternoon and evening hours -- though confidence
remains very low with regard to whether or not convection will
develop. The latest guidance suggests that convection may be
confined further north (over eastern Wyoming and western
Nebraska).. where NW flow aloft will be stronger.. and small
amplitude waves /DPVA/ more likely to be present.
.LONG TERM...(Saturday through Thursday)
Issued at 135 PM MDT Thu May 28 2020
Large, amplified, slow moving upper ridge will be the dominant
feature this period. It will begin the period with the axis over
the Rockies and by Thursday only have reached the Mississippi
River Valley. Temperatures will be above normal the entire period,
with the hottest days being Monday and Tuesday with upper 90s to
lower 100s possible. Thunderstorm chances will be low with the
lack of upper forcing under the ridge. Nonetheless, cannot rule
out a few diurnally forced thunderstorms migrating off the Front
Range during the late afternoon and evening hours just about every
day. Severe chances will be low due to lack of flow/deep layer
shear under the ridge. Fire weather parameters will be at their
highest on Monday and Tuesday when relative humidity is forecast
to drop into the 15-20 percent range. Surface wind speeds,
however, will be marginal, and fuels are also beginning to green
up with recent rainfall.
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 459 PM MDT Thu May 28 2020
Another round of VFR conditions is expected for both taf sites
during the forecast period. High pressure over the region will
give KGLD/KMCK scattered mid/high clouds.
Winds for KGLD, NE around 10kts thru 05z Friday, then SE 5-10kts.
by 08z, light/variable becoming SE around 15kts by 15z.
Winds for KMCK, NE around 10kts thru 08z Friday, then
light/variable. By 15z, meandering from ESE to SSE around
Area Forecast Discussion
National Weather Service Jacksonville FL
932 PM EDT Thu May 28 2020
Scattered showers and thunderstorms continue across inland parts
of the forecast area this evening. The main concentration has been
over extreme southeast GA over the past few hours where the
airmass never got worked over during the afternoon convection.
Additional showers and a few storms continue over inland northeast
FL around the Suwannee Valley area down to central and west
Marion county. General trend is for convective intensity to
diminish. Model guidance not doing a good job with current radar
trends, and the HRRR looks a few hours behind the state of the
radar. For the update, continued to show a diminishing trend with
convection by late evening but have left in best chances of
showers and potential storms rest of tonight for the zones
closest to the Gulf of Mexico, given the fetch of mid-level southwest
winds bringing in unsettled wx from the Gulf waters overnight,
and aided by shortwave troughing rotating around the main
mid/upper level low centered over central MS valley area.
Another round of showers and storms expected Friday, with best
chances in the afternoon hours. Coverage may be higher than
Thursday, and still expecting locally heavy rainfall, frequent
lightning, and gusty winds with storm activity. Localized flooding
will be a concern with this activity given the relatively wet
conditions over the past several days.
Current forecast was on track with little change with southerly
flow about 10-15 kt and seas 2-4 ft. A few showers and storms will
remain possible overnight.
.PREV DISCUSSION [758 PM EDT]...
.NEAR TERM [Through Tonight]...
Moist airmass in Southwest flow aloft and Precipitable Water
Amounts of 2 inches or more will continue to aid in scattered
convection across SE GA this afternoon and numerous to widespread
convection across NE FL as Atlc Coast Sea breeze moves inland and
interacts with ongoing across NE FL that will meet over the St
Johns River Basin and intensify as it drifts E-NE towards the I-95
corridor and JAX/SGJ metro areas during the late afternoon/early
evening hours and this is where the greatest threat of localized
flooding will be, mainly in the urban areas that have received
recent heavy rainfall and localized amounts of 1-3 inches are
possible before sunset, with a decreasing trend in convection
towards midnight. Trof axis across inland SE GA this afternoon
also a possible focus for strong to isolated severe storms with
damaging wind gusts of 50-60 mph in addition to locally heavy
rainfall threat but Hi-Res convection models not as robust on this
scenario yet, but better wind fields aloft over inland SE GA will
support isolated severe storms tracking off towards the NE at
faster speeds through the evening hours. Only isolated convection
expected to linger during the overnight hours with muggy lows in
the lower 70s inland and mid/upper 70s at the coast. Some patchy
fog possible in areas that receive rainfall this afternoon and
.SHORT TERM [Friday Through Saturday]...
Cold front will continue to slowly sag through the SE US and into
the SE GA/NE FL region through this period and expect higher than
normal rainfall chances with locally heavy rainfall the main
threat each afternoon and evening as coverage increases to 60-90%
over the region both days as local sea breezes push inland and
interact with ongoing convection. This will allow for some strong
storms with gusty winds to 40-50 mph at times, but widespread
severe weather is not expected. Rainfall amounts of 1-2 inches are
expected for most areas, with locally higher amounts of 2-4
inches possible along the I-95 and US 301 corridors and some local
urbanized flooding issues can be expected in the JAX/SGJ metro
areas due to recent heavy rainfall. Humid conditions will continue
with Max Temps generally in the upper 80s/near 90 inland and mid
80s at the coast.
.LONG TERM [Sunday Through Thursday]...
Sunday...Slow moving front will slowly push SE of the region by
Sunday Night and expect one more round of scattered showers and
storms across NE FL during the afternoon hours followed by drier
conds Sunday Night with clearing skies.
Mon/Tue/Wed...Unseasonably dry airmass will filter into the
region from the North as High Pressure Ridge builds over the area.
Precipitable Water Amounts will fall below one inch through this
time frame and basically shut down afternoon convection with
rainfall chances around 10 percent or less. The breeze
onshore/E-NE flow will hold temps below normal as well with Highs
in the lower 80s along the coast and Mid/Upper 80s over inland
areas. Low temps will fall into the lower 60s inland and mid/upper
60s along the coast and airmass will feel quite different than
this weekend. While rain chances will be lower than normal the
breezy/onshore flow may bring an isolated shower from time-to-time
but thunderstorm activity is not expected.
Thursday...High pressure ridge breaks down and while airmass
remains drier than normal to keep rain chances less than 20
percent with a few isolated storms possible across NE FL. Temps
will rebound back to above normal levels with highs into the lower
90s inland and mid/upper 80s at the coast.
[Through 00Z Saturday]
Strongest storms are west-northwest of the TAF sites over inland
southeast GA. These cells are moving slow and will likely
dissipate before they reach the coast. Otherwise, some leftover
stratiform rain affecting areas around SGJ and GNV with brief
VFR/MVFR vsby over the next hour or so, and could affect VQQ soon.
Some light mist and low clouds will be possible toward early
morning Friday...at this time mainly anticipate around VQQ, GNV,
and SGJ. Another round of showers and storms appears likely Friday
afternoon and have included VCTS and PROB groups at this time.
Light and variable or southerly winds tonight and Friday morning.
Winds will turn south-southeast due to the east coast sea breeze
at JAX, SSI, CRG, and SGJ after 18Z Friday.
Ahead of the approaching cold front expecting a continuation of
South winds 10-15 knots and seas 2-5 ft through Friday, becoming
Southwest on Saturday, then shifting winds on Sunday with the cold
frontal passage. Northeast winds will develop Sunday Night and
expect East to Northeast winds at 15-20 knots and seas building to
5-8 ft Monday through Tuesday with Small Craft Advisory
Rip Currents: Low to Moderate Risk of Rips through the weekend
with breakers 2-3 ft, then potential High Risk on Mon/Tue as
surf/breakers build into the 3-5 ft range.
High moisture levels and rainfall will keep Fire Weather threats
to a minimum through the weekend. Drier airmass expected next week
with afternoon humidities around 35 percent over inland areas
will start to dry out fuels towards the mid-late week period.
While widespread 1-2 inch rainfall amounts are expected through
Sunday along the I-95 and US 301 corridors with isolated 3-4 inch
totals, mainly localized flooding threat will exist each afternoon
and evening with main stem river basins remaining below flood
stage. May need to keep an eye on urban flooding potential for the
JAX/SGJ metro areas on Friday/Saturday along with possible higher
risk smaller river basins such as Black Creek and the Upper Santa
River Basin as localized flooding will be a greater threat due to
recent heavier rainfall over the past week.
.PRELIMINARY POINT TEMPS/POPS...
AMG 70 87 69 87 67 / 20 70 50 70 20
SSI 74 83 72 84 71 / 20 70 60 80 30
JAX 72 89 70 88 70 / 20 90 50 90 30
SGJ 72 86 71 87 71 / 40 70 50 70 40
GNV 70 89 69 89 69 / 50 90 40 80 10
OCF 70 89 69 89 69 / 60 90 40 70 10
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
934 PM EDT Thu May 28 2020
A warm and moist air mass will prevail through Friday. A cold
front will then move through the area Saturday morning. High
pressure builds over the area early next week. A warm front will
will move through the area Wednesday.
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
0120Z regional radar is showing a diminishing trend over the
past hour, with just a few showers over the Potomac Highlands,
and some showers in the I-81 corridor south of Staunton. The 00Z
HRRR is showing some enhanced clusters of showers and storms
developing over south-central Virginia shortly after midnight,
and increasing in intensity and areal coverage as it moves north
to a position near southern MD by daybreak. So while the bulk of
the CWA will be largely dry overnight, the southeast portion has
increasing likelihood of showers and tstms as the night turns to
day. Overnight lows will be above normal, with temps in the
upper 60s outside the metro areas to lower 70s in urban areas.
Also expecting low clouds and patchy fog to develop in the 08Z-
12Z timeframe, predominantly east of the Blue Ridge.
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
A potent mid-upper level trough will approach the area during
the day tomorrow. Low clouds will be in place to start the day
to the east of the Blue Ridge, with a mix of sun and clouds to
the west of the Blue Ridge. The clouds to the east of the Blue
Ridge will gradually burn off through the morning, with ample
heating occurring across the area. Temperatures are expected to
climb well into the 80s across the entire area. The combination
of warm temperatures, dewpoints around 70, and height falls
aloft in association with the mid-upper level trough will result
in 1500-2500 J/kg of MLCAPE by late afternoon. As flow
increases aloft ahead of the mid-level trough, ample shear will
also be in place, with 0-6 km shear values of 30-50 knots. As a
result, strong to severe thunderstorms are expected to develop
tomorrow afternoon. The storms are initially expected to form
across western MD and the WV panhandle and gradually progress to
the east. Model soundings indicate capping between 800 and 900
mb through much of the day along the I-95 corridor, so storms
aren`t expected to make it into the metro areas until very late
afternoon or evening. Overall, the greatest severe threat
appears to be across western portions of the forecast area,
where winds will be strongest aloft. Both multicell clusters and
supercells appear possible given the parameter space in place.
In terms of hazards, damaging winds will be the greatest threat,
with hail also possible in any supercells that form. The low-
level wind field will be on the weaker side until evening, so
the tornado threat is expected to be low, but non-zero. Current
thinking is that storms should be rather progressive, so the
flood threat should be minimized. However, it`s worth noting
that consecutive runs of the HREF have highlighted the
potential for heavy rainfall across portions of western
MD/eastern WV panhandle, so that potential will need to be
monitored as well.
Any storms should gradually weaken trough the evening hours.
Eventually the system`s cold front will progress through
tomorrow night, ushering cooler and drier air into the area for
the weekend. Depending on the progression of the front, showers
and storms could potentially develop Saturday afternoon from
Central Virginia to Southern Maryland, but that appears to be a
low-chance possibility at the moment.
.LONG TERM /SUNDAY THROUGH THURSDAY/...
Large scale upper trough axis will be crossing the area around
12Z Mon. Upper level convergence behind it will lead to
subsidence and surface high pressure to build into the area. It
will be "chilly" Monday for early June standards. Won`t rule out
frost potential over the Potomac Highlands Tue morning under
clear skies and light winds.
High moves offshore Tue and heights begin to rise leading to a
warming trend. A warm front is expected to push east of the area
early Wed with a return of more humid conditions and the next
chance of showers.
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
VFR for the start of the overnight for most all terminals except
KBWI and KMTN where MVFR conditions for CIGS have developed
since sunset. Expecting this trend to MVFR to continue for all
terminals, including some patchy fog developing around daybreak.
Conditions should gradually improve back to VFR tomorrow
morning, with prevailing VFR conditions through the afternoon
hours. Showers and thunderstorms are expected to form tomorrow
afternoon, initially across western portions of the forecast
area. These storms could impact MRB as early as mid-afternoon,
but showers/thunderstorms should hold off at the major hubs
until late afternoon or evening. Conditions should improve to
VFR on Saturday in the wake of a cold frontal passage.
Fair weather expected Sunday through Tuesday under high
There could be a break in the winds tonight and early Friday.
Have generated a SCA for the Chesapeake Bay and surrounding
waters for Friday afternoon and evening. Some strong thunderstorms
will also reach the waters later Friday evening, with the strong
possibility of Special Marine Warnings being issued at that
SCA conditions possible Sunday into Monday in NW flow.
MARINE...Small Craft Advisory from 2 PM to 10 PM EDT Friday for
Area Forecast Discussion
National Weather Service Nashville TN
851 PM CDT Thu May 28 2020
FOR EVENING DISCUSSION.
Convection decreasing in intensity and coverage at this time.
Additional shower activity is located across northern AL but it
too is beginning to decrease. Current fcst appears to be on track
with the pops ratcheting down to just 20 percent for the
overnight. Hrrr attempts to invoke a few pops up showers late but
this looks iffy. Overnight lows still look like the lower 60s for
most areas by sunrise. Will go ahead and update zones in the next
hour to remove the higher pops from earlier.
00Z TAF DISCUSSION.
Showers and a few storms have developed in Middle TN this evening.
Look for these storms to either move through or end by 02Z. MVFR
vis is possible with a direct hit, but VFR is more likely to
Winds will pick up tomorrow, with a few gusts of 15-20 kts,
shifting to the northwest as a front moves through Friday