Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/29/21
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
826 PM MDT Fri May 28 2021
.UPDATE...
The Severe Thunderstorms Warning has been cancelled as convection has
moved south and east out of the forecast area into Eddy and Lea
Counties and into the TX Panhandle. Updated zone forecast is out.
Thanks to all of the storm reports sent in for today`s severe
weather!
24
&&
.PREV DISCUSSION...521 PM MDT Fri May 28 2021...
.AVIATION...
00Z TAF CYCLE
Scattered thunderstorms continue across eastern New Mexico this
afternoon. The threat for strong to severe storms will continue
through about 03Z when the storms should then move into west TX.
Main threats continue to be heavy rain, frequent lightning, large
hail, and damaging winds. Outflow boundaries propagating westward
along with sufficient low-level moisture will cause low-clouds with
MVFR to IFR ceilings to redevelop for areas along and east of the
central mountain starting around 06Z and continuing through mid-
morning. The east canyon wind is still expected at KABQ, but wind
speeds should remain below 35 knots. Therefore, an Airport Weather
Warning is not anticipated.
15
&&
.PREV DISCUSSION...314 PM MDT Fri May 28 2021...
.SYNOPSIS...
Strong to severe thunderstorms will be the rule during the afternoons
and evenings in eastern New Mexico this evening through at least
Memorial Day. Best chances for afternoon and evening showers and
thunderstorms in the Rio Grande Valley and points west will be on
Memorial Day. High temperatures on Saturday will be near average,
cooling to below average Sunday and into early next week. Slight
chances for afternoon and evening showers and thunderstorms will
remain in the forecast through much of next week.
&&
.DISCUSSION...
.SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT)...
East to southeast flow at the surface continues for areas along and
east of the central mountain chain, complements of last night`s
backdoor cold front. Upslope flow has allowed for storms to develop
early this afternoon across the northern high terrain, and they are
slowly propagating east-southeast onto the lower elevations. These
storms will be entering an unstable and sheared environment which
will allow them to intensify through this evening. Aloft at 500mb,
westerly flow is present while farther up at 300mb, flow is more
northwesterly. While flow aloft is fairly week with only about 10 to
20 knots at 500mb, the curved hodograph indicates plenty of
directional shear. The latest SPC mesoanalysis indicates plenty of
instability as well with 1000-2000 J/kg of MLCAPE from roughly San
Miguel County southward through Lincoln and Chaves counties. This
environment will support severe or supercell thunderstorms with the
primary threats being large hail and damaging winds. These storms
should develop into multi-cell clusters or linear segments as they
approach the NM/TX border this evening, and both the latest HREF and
HRRR guidance indicate the severe weather threat should be over by
03-04Z as the storms exit into west TX.
Outflow from these storms will surge westward tonight, helping to
reinforce low-level moisture as well as produce an east canyon wind
in the middle RGV similar to last night. Surface winds across the
east will veer more southeasterly on Saturday, limiting the upslope
component that`s present today. However, as an H5 low starts to take
shape to our west, a mid-level jet streak will be steered over the
CWA. While directional shear is reduced, speed shear increases
thanks to the jet streak. Additionally, upper-level divergence is
enhanced across the northeast corner of the state which will be
within the left exit region of the jet. With plenty of instability
remaining in place, Saturday will feature another round of strong to
severe storms again for the eastern portions of the CWA,
particularly the northeast where the latest SPC Day 2 Outlook
highlights a slight risk.
The other concern for Saturday will be the possibility for heavy
rainfall across the northeastern plains as well as areas along the
NM/TX border. By Saturday night, a shortwave disturbance over
southern CO will interact with another backdoor cold front. This
area of convergence combined with increased instability along the
front will help additional convection to develop. There also high
confidence with more than sufficient moisture with PWATs near to
even exceeding an inch. These PWATs are above climatology which adds
to the heavy rainfall confidence. Models are in fairly decent
agreement with the potential for heavy rainfall totals although
there are differences in placement. By Sunday morning, there is the
potential for some locations to see upwards of 2-3" of rain which
may produce flash flooding.
LONG TERM...(SUNDAY THROUGH THURSDAY)
Sprawling surface high pressure centered near the Great Lakes will
keep a southeasterly return flow going across eastern NM Sunday.
At the same time, a weak upper-level low over far southern CA is
forecast to slowly slide southeastward over northern Baja and
northwest Sonora during the day Sunday. This upper-low results in
surface low pressure developing over west-central NM Sunday
afternoon. Another round of strong to severe storms is likely across
much of eastern NM Sunday afternoon/evening with a strong westward
push of moist rain-cooled air surging westward Sunday night. Strong
east winds are forecast for the RGV Sunday night into Monday
morning. GFS and ECWMF agree that Gulf moisture associated with this
surge will be plenty deep to not get scoured out via afternoon
mixing west of the central mountain chain. Memorial Day still looks
like the best day for wetting showers and thunderstorms in the RGV
and points west. Out east, another round of strong to severe storms
is forecast underneath increasing southwest flow aloft ahead of the
above mentioned upper low.
Upper-level trough axis slides east of NM Tuesday. Enough residual
low-level moisture remains for a round of afternoon mainly mountain
convection Tuesday. The northern mountains and northeast
highlands/plains stand the best chances for convection Wednesday
thanks to atmospheric stretching (deformation) between a deep upper-
level trough to the east and a building high pressure ridge to the
west.
15/33
&&
.FIRE WEATHER...
There are currently no critical fire weather concerns over the next
week. A very active pattern through the holiday weekend will lead to
daily rounds of thunderstorms, especially across eastern NM. Storm
coverage this weekend will favor areas along and east of the central
mountain chain. Across the west, dry conditions prevail with minRHs
in the single digits, however, winds will remain relatively light.
Chances for wetting precipitation increase for central and western
NM Monday and Tuesday as low-level moisture being pushed westward to
the Continental Divide should result in an uptick in storm coverage.
Chances for storms and wetting precipitation will gradually trend
down by the middle of next week as winds continue to remain light.
15
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Denver/Boulder CO
752 PM MDT Fri May 28 2021
.UPDATE...
Issued at 752 PM MDT Fri May 28 2021
High based showers with a few weak storms mixed will continue to
progress eastward through the evening. A couple may linger past
midnight across the far eastern plains. Tweaked PoPs and sky cover
to line up with current trends. Latest HRRR runs bring low clouds
back to the Front Range Saturday morning, mainly after sunrise.
This looks on track with low level moisture increasing behind a
cold front. Increased cloud cover Saturday morning for this.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 327 PM MDT Fri May 28 2021
Shallow cumulus clouds continue to fester over most of the higher
terrain this afternoon, but we`ve yet to see any sustained
updrafts develop so far. Cloud depths have increased a little in
the past hour or so across far southern Jefferson county and
forecast guidance continues to show at least a few weak
showers/storms developing later this afternoon. We`ll maintain
slight chance for storms across much of the area, with storms
remaining very isolated. The severe threat is very low, but a few
of the stronger showers could produce some gusty winds this
evening. Showers should dissipate by early tonight. The rest of
the overnight hours should be pretty quiet with party to mostly
cloudy skies. Lows will remain in the low 50s for the plains and
the mid 30s for most of the higher terrain.
Tomorrow will mark the start of a cool and moist weekend for most
of northeastern Colorado, as a slow and weak trough axis moves
across the region. A weak frontal push should come through the
area tomorrow morning, with moist northeasterly flow continuing
through most of the day. With weak upslope flow extending through
roughly 700mb and increasing (but weak) instability...
characterized by a long skinny MLCAPE profile... we should start
to see convection develop across the higher terrain during the
early afternoon hours, with activity spreading into the plains
shortly after. The modest CAPE values over our Foothills/urban
corridor should limit heavy rainfall potential a bit, though
forecast PWATs remain near the 90-95th percentile for this time of
year. Storm motions tomorrow should also be relatively slow given
the weak flow aloft. Though the overall flash flood threat will
be fairly low, there are some concerns with the Cameron Peak and
Calwood burn areas.
In addition to the potential for heavy rains across the
Foothills, there is also a severe weather threat across our far
eastern counties tomorrow afternoon. Forecast guidance shows at
least a few storms developing off the Palmer Divide moving into
the far eastern Plains by the evening. There is some question of
how unstable the airmass ahead of these storms would be, with most
guidance suggesting about 1000-2000J/kg of MLCAPE. As mentioned
previously, flow aloft is quite weak, but there is enough
directional shear to promote a marginal severe threat. The primary
threat would likely be large hail, with a few strong wind gusts
also possible. Severe threat should quickly diminish by about 9PM
with just a few scattered showers and storms left.
.LONG TERM...(Saturday night through Friday)
Issued at 327 PM MDT Fri May 28 2021
The big questions for this forecast involve details of the
precipitation as the upper trough slowly moves across Colorado
Saturday night through Monday. Unfortunately, while the models are
in pretty good agreement on the big picture, there`s little
agreement on details. What we do know is that the air mass will
saturate along the east slope of the Front Range with persistent
but weak upslope and lift by Sunday morning, and across the rest
of eastern Colorado as the day goes on. The best lift will be over
the mountains late Sunday and across the plains Sunday night.
There`s agreement that mainly light winds and little temperature
gradient will keep large scale QG forcing weak, but a deep neutral
layer will also allow a good response to the lift that we have.
Without much cold advection, the snow level remains high, probably
above 10,000 feet though some models have a little more cooling in
their areas of heavier precipitation. The closest thing to a focus
is easterly winds against the east slopes of the Front Range, but
the wind speeds are 10-15 knots at best at the surface and become
weaker or less easterly with height. There`s also good agreement
that we maintain some westerly flow at 500 mb, though it gets down
to 10-15 knots in some models early Sunday before increasing
again.
What we don`t know is where any focus would be. Lacking this, we
get a prolonged period of mainly light rain, possibly moderate
rain for a few hours as that band of synoptic scale lift comes
over. No doubt there will be some smaller scale feature such as a
surface boundary on the plains or a weak eddy or shear zone in
the low to mid level flow that may be tied to earlier convection
elsewhere that will provide one or two foci for localized heavier
rain. This is most likely to be an issue Sunday afternoon and
evening when it won`t take much to produce a pocket of deeper more
productive convection. But each model picks a different place and
time, ranging from Pikes Peak to Larimer county and Sunday morning
through Sunday evening. So we`re not able to get any more focused
with a possible flood threat, and this might not change until this
feature develops. Outside of a possible focus, there`s agreement
on rainfall amounts generally between 0.5 and 1.5 inches with the
heavier amounts in the foothills and just east. Most of the models
do produce an area that gets over 2 inches, but in bullseyes in
different places.
So the flood threats, from most likely to least likely are:
1. Steady rain in the new burn areas east of the Front Range
Sunday that produces an inch over a few hours, enough for minor
flooding.
2. Slow moving storms over the burn areas that are localized but
produce an inch of rain in an hour. This will likely happen
somewhere, but will it be over a burn area?
3. Slow moving storms over the plains that produce a couple inches
of rain in a few hours. Plains storms will probably wind up moving
into the inflow eventually, making this less likely.
4. Thunderstorms west of the Front Range will have less moisture
to work with, but will be slow moving and could have stronger
updrafts. There is a low risk of storms producing an inch of
rainfall in an hour in that area on Sunday afternoon.
Monday there`s some drying coming in from the north, but that
could just allow for enough heating to redevelop convection. Still
slow motions, low flooding threat, and upslope winds. After that,
there`s a warming and drying trend with the models with about a
day`s difference between models on how quickly it warms up.
There`s a bit of a trend toward a slower warm up which could keep
us in the 70s with low grade storm activity through Thursday,
where the more aggressive operational GFS has us in the 80s and
dry by Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 752 PM MDT Fri May 28 2021
The threat for wind shift from showers will continue to decrease
through the evening hours. By 06Z, southerly drainage winds are
expected. A cold front will push through around 12Z and increase
low level moisture. Low clouds with ceilings of 500 will be
possible at KDEN and KBJC. The best time for this will be 13-17Z.
With increased moisture over the area, there will be better chance
for showers and thunderstorms Saturday afternoon and evening.
&&
.HYDROLOGY...
Issued at 327 PM MDT Fri May 28 2021
Flash flooding threat will be negligible tonight with no
precipitation expected over the burn areas. Flooding concerns
increase during the late morning and afternoon hours tomorrow as
scattered showers and storms develop over the Front
Range/Foothills. Above average moisture and slow storm motions
could promote heavy precipitation rates, but instability is rather
weak. Still, any slow moving storm that develops over burn areas
could pose a threat for some flash flooding. Most flooding
concerns will be contained to burn areas on the east side of the
divide.
Widespread light to moderate rainfall is expected on Sunday. There
is a threat of localized heavy rain that could cause flash
flooding in the new burn areas. The threat is greatest on the
Cameron Peak and Calwood burn scars on Sunday afternoon.
Elsewhere there is a lower threat of flooding. There may also be
some minor flooding from prolonged steady light to moderate
rainfall on the new burn scars from Saturday night through Sunday
night or Monday morning.
On Monday there will be a lower risk, but still some threat of
flooding on the Cameron Peak and Calwood burn scars. After that,
storms will likely be weaker or moving faster and the threat of
flooding will be much lower for several days.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Meier
SHORT TERM...Hiris
LONG TERM...Gimmestad
AVIATION...Meier
HYDROLOGY...Hiris/Gimmestad
Area Forecast Discussion
National Weather Service Charleston SC
1016 PM EDT Fri May 28 2021
.SYNOPSIS...
A cold front will push through the area Saturday night,
followed by high pressure from the north into the middle of
next week. The high will then move further offshore late in the
week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Early this evening: Regional radar imagery shows a line of
convection that stretches across southeast Alabama into central
Georgia and the Upstate of South Carolina. The overnight is
expected to be dry and the forecast continues to follow the HRRR
and RAP which both show the upstream convection dissipating
before it reaches the interior zones of the forecast area. We
have maintained rain chances in the 20 percent range across
Allendale, Screven, Jenkins, Bulloch, and Candler counties
around sunrise Saturday.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
Saturday and Saturday night: A deep, but positively tilted
trough will develop across the Ohio and Tennessee Valley
Saturday, then move into the area at night as it becomes more
neutrally oriented. At the surface, a northeast to southwest
aligned cold front will drift through the Southeast, reaching
the forecast area during the evening, and passing offshore
before midnight. The front has a slow progression into and
through the area initially since it is generally parallel to the
flow aloft, and there is expected to be at least one wave of
low pressure forming along the front over the Midlands and/or
Pee Dee of South Carolina.
While we can`t rule out a few showers and t-storms along the
northwest tier early on with a weak short wave, much of the
morning will be under the influence of subsidence and NVA in
wake of this feature. The better chances for convection will
come in the afternoon and the evening, as the front draws a
little closer and there is the interaction of boundaries with
the sea breeze that looks to reach close to or a bit east of the
I-95 corridor.
Deep layered shear isn`t overly impressive and MLCAPE looks to
be only around 1000-1500 J/kg. Given quite a bit of dry air
above 600- 700 mb, the strength of the updrafts will be somewhat
curtailed. Thus we have gone no higher than 40% PoPs. But it
looks to be the first rainfall for many places in over two
weeks, albeit generally less than 1/4 inch.
Where there is an interaction of boundaries the updrafts could
tap into some of that drier mid level air, and maybe result in
an isolated non-zero severe risk.
Convection will wane quickly from west to east at night, as the
cold front pushes into the ocean, and a post-frontal trough
moves in the South Carolina counties overnight from the north.
Temperatures look to peak close to 90F everywhere inland from
the barrier islands, and with the arrival of a somewhat cooler
and drier air mass after midnight, lows will fall to the upper
50s and lower 60s most places inland; middle 60s along the
coast.
Sunday through Monday: The trough aloft passes through on
Sunday and is followed by zonal flow on Monday. Simultaneously
at the surface, high pressure builds from the north Sunday, then
shifts into the immediate Atlantic waters Monday. The lack of
forcing and moisture will preclude any mention of rainfall. It`s
a noticeable change in air mass from what we`ve recently had,
and the resulting temperatures will end up below climo.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
High pressure building near the coast and over the Atlantic
will block any upstream cold fronts from getting this far
southeast through the entire week. The zonal flow aloft will
temporarily give way to ridging, before the next trough develops
far to the west and northwest Thursday and Friday. The first
half of the week looks to have minimal forcing for ascent and/or
moisture, but some better forcing and moisture arrive by later
in the week. For now we have no rainfall in the forecast through
Tuesday night, small chances Wednesday along the sea breeze,
then higher chances Thursday and Friday. Thermodynamics and
shear aren`t that impressive, so the severe potential looks
quite low at this stage. Temperatures will climb to near or even
slightly above climo given 850 mb temperatures and low level
thickness near or above average for early June.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions are expected to prevail through 00z Sunday. The
main forecast challenge will be the potential for showers and
thunderstorms Saturday afternoon. Isolated to scattered showers
and thunderstorms are anticipated across the area, but
confidence in direct impacts is low. For now, have introduced a
VCSH at KCHS, KJZI, and KSAV beginning around 18-19z. Can`t rule
out some brief reductions in visibility as showers and
thunderstorms pass through, but details including timing and
likelihood will have to be worked out with subsequent TAF
issuances. Southwest winds could gust up to around 20 knots in
the afternoon.
Extended Aviation Outlook: VFR conditions are expected to
prevail. Diurnal convection could occur Wednesday, mainly on
the sea breeze.
&&
.MARINE...
Tonight: The local waters will sit in a relatively tight
southwest to northeast pressure gradient area ahead of a cold
front. This setup will keep southwest flow elevated through the
night, mainly in the 15-20 knot range. The zone with the best
chance for frequent 25 knot gusts will be the Charleston County
waters and a Small Craft Advisory has been issued through 8 am.
Seas will increase through the night, becoming 3-5 feet in the
latter portion of the period.
Saturday: The pressure gradient will tighten between the sub-
tropical ridge and an upstream cold front through the day. That
along with a boost from the sea breeze will push winds close to
advisory levels in Charleston Harbor and on the Charleston
County Atlantic waters during the late morning and afternoon.
On average winds will be SW at 15 or 20 kt, with gusts as high
as 25 kt or so, especially over AMZ330 and AMZ350. Seas will
hold around 3 to 5 feet, and highest on the Charleston County
ocean waters.
Mariners should remain alert for isolated to scattered t-storms
moving in late in the day and during the evening hours.
Saturday night: The cold front will move through the marine
area early at night, clearing the local waters by 06Z. This is
followed by a weak post-frontal trough from the north late at
night over the South Carolina zones. Winds will shift from SW
early on to the W and NW behind the cold front, then clock
further around to the NW and N with the trailing trough. Any
lingering 25 kt gusts in the evening will come to an end, and
winds and seas will stay below advisory thresholds thereafter.
Sunday through Wednesday night: High pressure will dominate
conditions as it builds in from the north early in the week, and
eventually slide into the ocean and gradually further offshore
with time. No advisory conditions appear to occur through the
entire forecast period.
Rip Currents: Although there is some question as to how much
swell energy will reach the beaches, given that it is a holiday
weekend and to better "mesh" with WFOs ILM and JAX, we opted for
a Moderate Risk of Rip Currents at all beaches Saturday.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 8 AM EDT Saturday for AMZ350.
&&
$$
NEAR TERM...BSH
SHORT TERM...33
LONG TERM...33
AVIATION...BSH/33
MARINE...BSH/33
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
709 PM CDT Fri May 28 2021
.UPDATE.../SVR 221/
Replaces 218 and 220 and valid through 07Z.
&&
.AVIATION.../00Z TAFS/
Strong to severe storm complex moving through AUS at 00Z issuance
time. With strong winds associated with this segment of storms, the
chance for improving conditions will happen faster that at the other
3 TAF sites. SAT/SSF/DRT will probably see a couple rounds of
convective cells with shifty and unpredictable wind directions
possible through 06Z in San Antonio and through 08Z at DRT. AUS
probably has the higher potential for a severe wind speed however.
Mostly VFR skies should follow, but guidances call for some
intermittent MVFR or even some IFR cigs with residual shower
activity. Will stick with the more stable and fair solutions and
adjust later if necessary.
&&
.PREV DISCUSSION... /ISSUED 431 PM CDT Fri May 28 2021/
UPDATE.../ADDED LLANO TO WATCH #218/
A new severe watch may be in the plans for later this evening, but
severe storms are grazing the northern border of Llano County. Watch
218 was expanded to buy some time until 00z for Llano.
PREV DISCUSSION... /ISSUED 308 PM CDT Fri May 28 2021/
SHORT TERM (Tonight through Saturday Night)...
Storms firing along an front/outflow boundary over Central TX will
likely threaten Burnet/Williamson/Lee counties by aroun 20Z.
Moisture rich environment as the storms move south should make for a
slightly more skinny CAPE profile over time and lead to heavy rain
and damaging winds and 1 inch hail as the elevated threats as the
storms expand south into the metro cities in the evening hours.
A new weather watch may be needed for western counties shortly (per
MCD #786), and this will be over an area where >2 inch hail threats
are higher, with cooler and drier air aloft west of a line from
Burnet to Boerne to Crystal City. The dry-line is pretty far to the
west, so the first storm cells that enter this delayed threat area
may also me coming from the front/outflow boundary to the north.
Colliding cells and the high pwat levels near 2 inches will congeal
the storms into an MCS with a solid line expected by the time San
Antonio is impacted. Judging by the last few runs of the HRRR the
severe and heavy rain threat may ease up over AUS as early as 9 pm.
However, the coarser scale models do less with outflows and show
more late night activity through the I-35 corridor rooted toward an
amplifying mid level trough. Where the developing frontal boundary
is by midnight should help determine whether the threat continues in
to the early morning hours. At this time would guess the severe
threat could last into around 09Z over the Rio Grande Plains.
Most of the models depict a shortwave mid level ridge over Texas to
combine with the overworked low level airmass. Thus low chance PoPs
over eastern counties and little to no rain is expected over western
counties for most of daytime hours Saturday into Saturday night.
LONG TERM (Sunday through Friday)...
Sunday should be the driest day of the forecast, but still will
carry low chances for some afternoon convection. Another shortwave
to move through the area from the southwest leading to storm
development over the higher terrain in Mexico, then moving east into
the Rio Grande Plains Sunday night. Continued disturbances Monday,
along with a cold front positioned to our north will enhance rain
chances Monday into Tuesday. By mid to late week, a deepening long-
wave trough that extends through the Plains into Mexico will fire
off more shortwaves through the area into the end of the week. This
extended wet pattern could lead to isolated areas of flash flooding,
as there has been little time to recover from the past rain events.
Temperatures will be mild and slightly below normal, though the
humidity will make it feel warmer.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 68 83 69 82 68 / 70 40 10 30 -
Austin Bergstrom Intl Airport 67 83 68 82 68 / 70 40 - 20 -
New Braunfels Muni Airport 70 85 69 84 69 / 80 30 - 20 -
Burnet Muni Airport 67 82 66 81 67 / 70 40 - 20 10
Del Rio Intl Airport 71 89 74 88 73 / 60 10 20 30 40
Georgetown Muni Airport 67 82 67 81 67 / 70 40 10 20 10
Hondo Muni Airport 69 87 70 86 70 / 80 20 - 10 10
San Marcos Muni Airport 68 84 68 83 68 / 70 30 - 20 -
La Grange - Fayette Regional 71 84 69 84 69 / 70 50 10 20 0
San Antonio Intl Airport 69 85 69 84 70 / 80 30 - 20 10
Stinson Muni Airport 71 87 71 86 71 / 80 30 - 20 -
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...Oaks
Long-Term...KCW
Decision Support...33
Area Forecast Discussion
National Weather Service Gray ME
939 PM EDT Fri May 28 2021
.SYNOPSIS...
Low pressure will pass south of the region tonight bringing rain to
southern and central areas. Rain will taper off on Saturday but
conditions will remain cool and cloudy. Another low pressure
system will move up the Atlantic coast on Sunday and Sunday
night with rain overspreading the region again. Showers are
expected to slowly give way to improving conditions on Memorial
Day with quiet weather and moderating temperatures through
midweek.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
940 PM Update...Adjusted PoPs just a tad for the next few hours
based on the progress of the northern edge. Tightened the PoP
gradient up a little bit. Otherwise, no significant changes to
the going forecast.
625 PM Update...Very little change to the going forecast other
than to lower temperatures a bit where it`s raining. It`s 49
degrees in Keene NH, with some readings around the 44 degree
mark at higher elevations in the Monadnocks. Otherwise, PoP
timing looks really good going forward.
Previously...
High Impact Weather Potential:
* Frost possible along the Canadian border.
* Locally heavy rain far southern NH tonight.
Pattern: Early afternoon water vapor imagery shows a shortwave
trough building into the Great Lakes Region...with a moisture plume
east of this feature originating in the Gulf of Mexico and arcing
north and east into New England. Another...more subtle shortwave is
located over southeastern Ontario...moving south and east along the
southern flank of much larger scale troughing centered over Labrador
Drilling down to the surface...there is a weak area of low pressure
taking shape east of the Great Lakes trough over the Ohio Valley
with a precipitation shield to it/s north and east in a region of
frontogenetical forcing. The movement of this low and it/s
attendant precipitation shield will be the primary forecast
concern through tonight...as this feature pushes towards ridging
that is centered over James Bay...but is supplying dry...cool
Canadian air from the north.
Through this Evening: Clouds will continue to stream in from the
west with rain slowly edging eastward, but struggling as it
encounters 20-25F dewpoint depressions over southern NH. Rain
through 8pm will be light...and confined to the lakes region and
points south in NH. From MHT-ASH east there may only be a few
sprinkles by this point. 8pm temperatures will be in the 40s in
the mountains...and low 50s to the south.
Tonight: Low pressure pushes east along baroclinic zone stalled
south of New England overnight. As it does so...impressive band of
mid level frontogenesis strengthens below right entrance region to a
150kt jet streak at H2 with an easterly low level jet strengthening
to 30-40kt north of the stationary front. PWATs above 1.5" will be
available south of the boundary. The setup suggests good low/upper
level coupling of forcing for ascent with this combination of
variables yielding a band of moderate to locally heavy rain
over southern NH and far southern ME. The northern edge of the
rain shield should be sharp with dry Canadian air still poised
to the north. Some uncertainty remains with this as the 28.12Z
NAM has shifted northward along with the EC/GFS...but with
recent HRRR runs as well as the CMC global and regional a bit
further south. Have edged PoPs northward just a bit with the
majority of any rainfall remaining along/south of a LEB-IZG-LEW-
RKD line. Rainfall amounts will increase as you head south with
overnight values nearing 1" along the MA border. This could
cause some localized ponding of water...but no significant
flooding is expected.
At the other edge of the forecast area...some breaks in the
clouds and very low dewpoints will allow for another round of
chilly overnight lows. Stayed above the MOS guidance which was
far too warm in many locations last night...with mid/upper 30s
over our northern tier of zones. Areal coverage of temps in the
lower 30s is very small /right along the international border/
and therefore have held off from any frost/freeze headlines.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
High Impact Weather Potential: Minimal.
Saturday: Wave of low pressure south of Cape Cod will push north and
east to a position south of Halifax by Saturday evening as mid level
shortwave shifts east. Precipitation shield will slowly erode from
northwest to southeast as this occurs. While somewhat drier low
level air will slowly push in from the north through the day...the
mid level cloud deck looks to hold tough for all but far northern
areas. Low level northeasterly trajectories portend a chilly day
and the raw 2M temperatures in the guidance agree well on this
point. With showers continuing through some of the morning over
southern areas...and deeper moisture remaining entrenched
here...expect the coolest highs...with values struggling to reach
50. These values will challenge record low high temperatures for
the date /45 at KCON in 1917 and 49 at PWM in 2017/. Further
north where skies will be a bit brighter...mid/upper 50s are
expected.
Saturday Night: Northeasterly flow continues as high pressure
remains centered just north of Maine with another area of low
pressure taking shape off the Mid Atlantic coast as upstream
shortwave begins to close off as it nears the coast. As the flow
aloft begins to back...deep moisture will start lifting north once
again with cloudy skies likely to dominate the period. Isentropic
ascent over the warm front to our south may bring showers into our
far southern zones before daybreak. As for temperatures...the
deepening cloudiness will result in a rather small diurnal
range...with temperatures along the coast into the foothills only
falling into the lower 40s...with upper 30s in the mountains.
Finally...with a strengthening gradient...northeasterly winds will
freshen overnight...particularly along the coast with 10-20mph winds
continuing through the overnight.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Overview...The second half of the Memorial Day weekend looks wet, at
least late Sunday into Sunday night, but showers/rain will linger
into Monday morning as well. Conditions dry out Tuesday and
Wednesday before a rather large storm system over the Great Lakes
may bring chances for showers to the region for the latter half of
the week. Cool temperatures will gradually warm over the first half
of the week and peak around mid-week.
Impacts...While the overall impacts from rainfall late Sunday into
Monday morning will not be meteorologically significant (i.e.,
no flooding expected, etc.), will note the unfortunate timing
related to the holiday weekend.
Forecast Details...The focus of the long term will be on the first
two days of the period, Sunday and Memorial Day, as low pressure
looks poised to move up the New England coast late Sunday into
Monday. A period of beneficial rain for southern areas looks likely,
centered on Sunday afternoon into Sunday night.
Sunday begins with a closed upper-level low centered over the
eastern Great Lakes and the Ohio Valley with weak waves of low
pressure present along a quasi-stationary front off the East Coast.
One of those weak waves becomes enhanced with aid from the upper low
late Sunday, strengthening some as it slowly moves up the New
England coast through Monday evening. An area of rainfall will begin
to move into southern areas late Sunday morning as the low develops,
gradually spreading northward through the evening and eventually
covering the entire CWA. The rain continues Sunday night and into
Monday morning before coming to an end sometime Monday afternoon as
the low begins to accelerate north.
As far as amounts...the 00Z GFS and Euro ensemble QPF data show that
the mean rainfall totals for Sunday through Monday morning for
Manchester and Portland are around an inch. However, Portland`s mean
lies above its 50th percentile in the Euro ensemble while
Manchester`s lies below its 50th percentile. Overall, both ensemble
and deterministic guidance suggests that western ME looks to have
the best chance for the highest rainfall totals. This forecast may
ultimately be a bit light compared to the latest guidance, but it is
higher than the previous forecast with room to trend in either
direction as we get closer to the event. Will also note that the
latest deterministic Euro is much slower than the latest GFS with
this system, potentially pushing rainfall into Tuesday...so fair to
say that there is still some overall uncertainty with this portion
of the forecast.
In the wake of that system, high pressure builds to our south,
eventually centering off the East Coast by Wednesday. This will
allow a broad southwesterly flow to develop over the Northeast
through mid-week. While temperatures on Sunday will continue to be
on the cool side, the southwesterly flow will allow a warming trend
to begin Monday and continue through mid-week. Other than a few
showers in northern areas Tuesday afternoon, we should remain dry on
Tuesday and Wednesday. Toward the latter half of the week, a large
baroclinic zone stretching into New England ahead of a large system
over the Great Lakes may bring some chances for showers to the
region on Thursday.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
Short Term...
Summary: Low pressure passing south of the region tonight will bring
rain to much of the area....with conditions gradually improving
Saturday afternoon through Saturday night.
Restrictions: VFR all sites at the moment. Rain arrives over
southern NH this evening...spreading north and east overnight.
Within the rain shield...conditions will deteriorate to
MVFR/IFR. VFR conditions will hold at HIE...with uncertainty
whether rain reaches AUG/RKD. Rain diminishes Saturday morning
with improvement to VFR Saturday afternoon and evening. VFR will
dominate much of Saturday night...but towards daybreak Sunday
rain may bring restrictions back to southern terminals.
Winds: Light winds /turning onshore along the coast/ will gradually
shift northeasterly tonight and increase to 12g18kts for the day on
Saturday. Northeast winds continue 5-15kts Saturday night.
Lightning: No lightning is expected through Saturday night.
LLWS: No LLWS is expected through Saturday night.
Long Term...Rain begins to overspread the region from the south
late Sunday morning, bringing associated MVFR/IFR restrictions
to all terminals by late Sunday afternoon. Rain continues
through Sunday night before ending late Monday morning through
early Monday afternoon. Breezy northeast winds on Sunday will
become lighter and more northwesterly through Wednesday as high
pressure builds into the region.
&&
.MARINE...
Short Term...Northeasterly winds strengthen over the waters
late tonight with SCAs likely for Saturday and continuing
through Saturday night.
Long Term...SCA likely ongoing for the outer waters Sunday
morning, and while winds should diminish beginning Sunday
afternoon, seas are expected to remain above 5 ft through Sunday
night and possibly into Monday morning. Rain is likely over all
zones Sunday and Sunday night and likely early Monday morning.
High pressure builds south of the waters late Monday, bringing
lighter winds and lower seas for Tuesday and Wednesday.
&&
.TIDES/COASTAL FLOODING...
Astronomical tides remain high through this weekend. While surge
values will increase slightly as low pressure passes south of
the region...tide heights are gradually decreasing and therefore
no significant coastal flood impacts are expected.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory from 8 AM to 6 PM EDT Saturday for ANZ153.
Small Craft Advisory from 4 AM Saturday to 4 PM EDT Sunday for
ANZ150-152-154.
&&
$$
NEAR TERM...Arnott/Ekster
SHORT TERM...Arnott
LONG TERM...Watson
Area Forecast Discussion
National Weather Service Lake Charles LA
1033 PM CDT Fri May 28 2021
.DISCUSSION...
Wx map shows weak sfc high pressure ridge over East Texas/Louisiana
this evening. Satellite and area radar imagery shows a Mesoscale
Convective Complex (MCS) centered just west of Houston. Earlier
short term guidance didn`t have as good a handle on this system,
but the latest HRRR guidance finally picked up the feature. The
result is more or less the same, with slow weakening as it moves
southeast, but additional development with the remnant outflow
boundaries possible across Southeast Texas/Southwest Louisiana and
adjacent coastal waters. For the most part, mainly adjusted the
evening chances of precipitation, with little adjustments
overnight. For the remainder of the forecast, no major changes
made.
DML
&&
.PREV DISCUSSION... /issued 644 PM CDT Fri May 28 2021/
DISCUSSION...
00Z 29MAY21 TAFs
AVIATION...
VFR conditions will prevail through tonight with possible MVFR
CIGS and VIS as a boundary reaches SETX and extreme western SWLA.
Isolated thunderstorms could develop along and ahead of this
boundary. Otherwise, tomorrow we can expect northerly /
northeasterly winds and mid to high level clouds.
Stigger/87
PREV DISCUSSION... /issued 420 PM CDT Fri May 28 2021/
SHORT TERM [Tonight through Saturday Night]...
A potentially active short term period is expected, though there
is not a great deal of confidence in the details this afternoon.
Frontal boundary to the north is progged to sink south through the
forecast area overnight, while clusters of showers and
thunderstorms initiating over central/eastern TX track generally
TWD the SE. Model guidance is a bit all over the place, but
generally agree that the current convective activity may glance
SE TX this evening, with the greater chance of rain coming
overnight into SAT morning as a shortwave trof approaching from
the west initiates new convection. Highest chances reside across
SE TX into far SW LA through the day, with rains expected to come
to an end during the evening as drier air filters in and the
shortwave departs to the east.
Seasonal low temperatures are expected tonight, with highs
tomorrow moderated by clouds/convection and post-frontal CAA.
Below normal lows are expected Saturday night, with upper 50s
across parts of central LA and lower 60s along the I-10 corridor.
13
LONG TERM [Sunday through Friday]...
The front that passes early during the weekend will stall over the
northern Gulf of Mexico and then start to move northward back into
our area Monday into Tuesday. This may lead to the formation of
showers and thunderstorms during these days. The front will weaken
and eventually dissipate sometime on Tuesday or Wednesday.
SREF shows a light amount of rainfall accumulation Monday evening.
However, GFS and WPC keep all accumulation along the western
periphery of our area until late on Tuesday. This forecast adds a
small amount of accumulation compared to WPC for Monday and Tuesday.
Severe weather will not be expected early in the week.
An additional frontal system will begin to make its way into our
area from the northwest on Tuesday. The broad cyclonic (counter-
clockwise) flow from the system will help to funnel moisture
northward from the Gulf of Mexico. It appears that the low pressure
center over Oklahoma will intensify Wednesday into Thursday,
strengthening the northward flow and leading to high chances for
precipitation. The GFS, ECMWF, and WPC agree on accumulations of
rainfall Wednesday evening into Thursday. A risk of severe weather
cannot be ruled out for the middle of the week (Wednesday and
Thursday).
The additional frontal system will be expected to stall and weaken
northwest of our area. It will then be expected to dissipate
Thursday evening into Friday. Rainfall chances will continue through
Friday.
55
MARINE...
High pressure will persist over the northeastern Gulf of Mexico
through tonight, with mostly light southerly winds persisting.
Winds will increase and shift to northeasterly during the weekend
as a weak frontal system drifts into the Gulf of Mexico. Light
onshore flow will return for early next week as the front lifts
back northward and washes out.
13
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 67 79 59 81 / 20 30 0 0
LCH 72 82 63 83 / 30 50 10 10
LFT 70 82 62 82 / 20 30 10 10
BPT 70 83 64 83 / 40 60 10 10
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Midland/Odessa TX
632 PM CDT Fri May 28 2021
.DISCUSSION...
&&
.AVIATION...
Have ongoing storms along the Pecos River moving into the Permian
Basin with additional storms moving down from Ern NM. Carrying
TSRA at INK... PEQ... and MAF. More storms expected overnight...
could see local MVFR cigs and vsbys with storms.
&&
PREV DISCUSSION... /issued 202 PM CDT Fri May 28 2021/
DISCUSSION...
KMAF 18Z RAOB shows a cap still in place, but considerably less than
the 12Z run. For some reason, the raob came in w/a sfc Td of 24C,
yielding mucapes of over 7000 J/kg! After editing the sounding for
a sfc Td of 19C, mucapes dropped to 3400 J/kg, which is still
potent. Mid-lvl lapse rates of near 9C/km and a wet-bulb zero of
8600` call for very large hail, and dcapes of 1300 J/kg suggest
damaging winds as well. Deep-lyr shear of 40 kts will help maintain
supercells, as will a 35+kt LLJ this evening. Radar already shows
the first cell going up nrn Brewster County, and this is in line
w/the latest HRRR run, which develops additional convection Permian
Basin late this afternoon, then SE NM this evening on a possible MCS
moving SE out of NM.
Saturday looks to be a little less active, w/the primary focus being
orographic lifting on easterly flow to the higher terrain out west
near the dryline. By Sunday afternoon, the west coast trough will
be over Baja del Norte, sending a strong shortwave into West texas
and Southeast New Mexico, w/Sunday night looking to be best chances
for rain this forecast, w/a continued severe threat. Monday night
looks wet/severe as well, as another shortwave calves off the
trough.
Chances drop off after Monday, but the trough remains parked over
Baja, and moisture isn`t going anywhere, so a chance of convection
remains in play each day. It goes w/out saying that temps will
remain below normal in this pattern, given expected convection/cloud
cover each day.
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 63 81 67 79 / 50 30 20 30
Carlsbad 64 87 67 85 / 20 20 30 50
Dryden 67 87 70 84 / 40 10 30 30
Fort Stockton 64 87 68 84 / 30 20 20 30
Guadalupe Pass 60 85 62 82 / 10 30 40 40
Hobbs 61 82 65 79 / 40 20 30 50
Marfa 58 89 62 84 / 10 30 30 40
Midland Intl Airport 63 82 67 80 / 50 20 20 40
Odessa 63 84 67 81 / 50 20 20 40
Wink 65 88 68 86 / 40 20 20 40
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&
$$
Area Forecast Discussion
National Weather Service New York NY
936 PM EDT Fri May 28 2021
.SYNOPSIS...
Unsettled weather is in store for the weekend, as waves of low
pressure move along a stationary front south of the area. One last
low pressure tracks near the coast Sunday into Monday, followed by
high pressure briefly returning on Tuesday. A slow moving frontal
system may impact the region mid to late next week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Temperatures have cooled fairly significantly as widespread rain,
locally moderate at times, overspreads the region. The rain will
continue for the majority of the night as surface low pressure over
the Ohio Valley redevelop off the Middle Atlantic coast tonight.
This is in response to an upper trough over the shifting towards the
Ohio Valley tonight.
In addition, strong southeast/easterly flow will increase overnight
as the surface low approaches. With decent low level/850mb flow,
moisture will continue to advect into the region, with PW values
nearing 1.5-1.75" per model soundings. Models have been pretty
consistent in advertising a period of heavier precipitation
overnight before tapering off early Saturday morning. HREF continues
to show a widespread 1-2" rainfall in across the area in the 6 hr
prob. matched means, with highest amounts across eastern LI and
southern CT.
Some of the heavier precip may be associated with remnant convection
that is currently near the DC metro. The HRRR has been continuing to
signal this activity lifting northward as the secondary low
redevelops off the Middle Atlantic. This convection should pass just
south of Long Island, but some heavier bands could move across
portions of Long Island and southeast Connecticut around or just
after midnight. A rumble of thunder cannot be ruled out here, but
have left mention out of the forecast since the airmass still
appears too stable.
Rainfall amounts by 12z Saturday should average around 1.5 to 2
inches across the area. Minor flooding is the main threat as the
rain falls in a relatively long duration.
Have also increased winds a bit overnight. Forecast soundings are
indicating a well mixed boundary layer up to just below 4 kft. Winds
at the top of the mixed layer average around 40 to 45 kt after
midnight. Do not think this intensity will mix to the ground, but
gusts 30 to around 35 kt are looking likely along the immediate
coast. Winds further inland should be weaker, but could still see
some gusts 25-30 kt.
Temperatures should fall into middle and upper 40s overnight.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/...
Uncertainty in the forecast with respect to precipitation
through Sunday. Light precipitation should continue into
Saturday morning, and begin to taper off for a period by
afternoon, as the surface low departs off to the east. The
aforementioned upper trough cuts off by Saturday night, and
slowly meanders northeast through the Great Lakes, becoming
positively tilted by Sunday afternoon, keeping the area in deep
cyclonic flow. Under gusty northeast/easterly flow and cloud
cover, temperatures will remain nearly steady through the day,
struggling to get out of the 50s. Shaved a few degrees off the
NBM deterministic for temperatures on Saturday as they`re near
the median. With spread from the upper 40s to upper 50s in the
inter-quartile range, this may still be a bit high, should
temperatures tonight cool to the wet bulb, especially northwest
of NYC, and have trouble recovering Saturday. Winds diminish
Saturday night as the low heads away from the area.
Another weak low pressure develops off DelMarVa by late Saturday,
with an inverted trough feature hanging to our south. This will
keep the area in extensive cloud cover Saturday through Sunday
evening, with precipitation chances increasing again by Saturday
night as the surface low approaches from the south. Guidance
differs a bit on the evolution of the track of this weak low, which
will impact our sensible weather. The NAM, CMC and EU have a more
westerly track up the coast through NYC, while the GFS is further
east off the coast of Montauk by early Monday. In fact, the EU
is the slowest of the guidance, keeping the low near the area
into late Monday. Have not bought off on this scenario just yet,
but worth watching in subsequent cycles. Nonetheless, precip
chances remain in the forecast Sunday into Monday morning, with
the bulk of the precipitation likely Sunday afternoon into
Sunday night, with another 0.25 to 0.5" possible across the
region.
The surface low exits the area Monday morning as the flow aloft
becomes zonal and the upper low shears out to the northeast.
After another day of easterly flow and cool temperatures on
Sunday, but a moderating trend under northwest flow begins
Monday, with highs back up in the low 70s.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
High briefly returns on Tuesday to keep us dry, then an
approaching warm front brings a chance of an afternoon shower on
Wednesday or Wednesday night. There is some question as to the
timing of this front with the faster GFS lifting it across area
on Wednesday while the ECMWF lifts it across the area Wednesday
night into Thursday. Once the warm front lifts to the north, the
region will lie between western Atlantic high pressure and yet
another longwave trough and associated low pressure and cold
front to our west. The trends are indicating both Atlantic and
Gulf of Mexico moisture transport will get involved. The axis of
the deepest moisture along with the timing and strength of both
the longwave trough and western Atlantic ridge will ultimately
play a role in determining the days with the highest probability
of rain. For now, have capped PoPs at high chance for the end
of the week owing to the uncertainty. High temperatures Tuesday
through the end of the week are expected to be near to slightly
above normal.
&&
.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
Low pressure will pass to the south tonight and then to the east
on Saturday and bring rain with gusty winds. The rain will be
heavy at times tonight as the low makes its closest approach,
then become lighter daytime Saturday as it pulls away. It
remains uncertain how strong winds may become overnight as the
low approaches. Some guidance is forecasting peak sustained
winds over 25 kt with gusts up to 40 kt, but think may be too
high and have gone with a more conservative 20-25G35kt.
Flight cat should lower to IFR in heavy rain tonight, then
gradually improve to MVFR in most places for daytime Saturday.
Cigs will likely be slower to improve E of the NYC metros.
Winds at FL020 should increase to 40-45 kt along the south
shore of Long Island, impacting mainly KISP and also
KLGA/KJFK/KBDR/KGON to a lesser extent, from about 06Z-12Z.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
AMD possible to fine-tune winds and flight cat.
.OUTLOOK FOR 00Z SUNDAY THROUGH TUESDAY...
.Saturday night...MVFR conds should lower to IFR late as rain
with another wave of low pressure starts to arrive. NE winds
G25kt along the coast.
.Sunday and Sunday night...Rain with IFR conds. NE winds
15G20-25kt, diminishing throughout and possibly shifting to
SE-S along the coast as low pressure tracks overhead or nearby/
.Monday...Lingering rain with MVFR to IFR possible. Improvement
and more dry conditions forecast for late day into Monday night.
.Tuesday...VFR.
.Wednesday...Possible MVFR with a chance of rain showers.
Detailed information, including hourly TAF wind component
forecasts, can be found at: http:/www.weather.gov/zny/n90
&&
.MARINE...
Gale conditions across all waters, except for NY Harbor and the
western LI Sound, where SCA gusts are probable, tonight through
Saturday morning as a surface low approaches. Ocean seas will
build tonight into Saturday, mainly 6-9ft through Saturday
morning. Gale conditions are likely across the western LI sound
and NY Harbor for a period on Saturday morning as well. As such,
a Gale Warning was issued for these areas for Saturday morning,
with gusts to 35kts likely.
Winds will diminish somewhat by Saturday night, but will remain
in SCA range with seas 4-6ft into early Monday across all ocean
waters. SCA conditions should subside by Monday afternoon.
Conditions on all waters will be below advisory criteria Tuesday
into Wednesday with a weak pressure gradient in place.
&&
.HYDROLOGY...
One to 2.25 inches of rainfall is likely tonight into Saturday,
resulting in some nuisance flooding in low lying and poor
drainage areas. Additional rainfall is possible mid to late
next week, but amounts are uncertain at this time.
&&
.TIDES/COASTAL FLOODING...
Widespread minor coastal flooding is likely with tonight`s high
tide. This is due to increasing E-NE flow and only about 3/4 to 1
1/2 ft surge needed to reach minor benchmarks. A coastal flood
advisory remains in effect for the south shore back bays, lower NY
Harbor, and Western Long Island Sound. Locally moderate flooding
cannot be ruled out, specifically across the most vulnerable
locations along the south shore back bays.
Impacts should be minimal with just isolated minor flooding across
the upper NY Harbor and a coastal flood statement remains here. A
coastal flood statement also remains for southwest Suffolk for
mainly along the western portion of the Great South Bay where
isolated minor coastal flooding is possible.
While astronomical tides are lower with the late morning/early
afternoon high tide on Saturday, isolated minor coastal impacts are
possible along the vulnerable locations along the south shore back
bays. Residual from the expected rainfall could also keep tide
levels higher. Saturday night`s high tide should also bring more
widespread minor flooding impacts across the south shore back bays
due to persistent NE flow. The coastal flood advisory for the south
shore back bays has been extended through Saturday night. A new
coastal flood advisory has also been issued for Saturday night`s
high tide along the lower NY harbor and portions of the Western
Sound along the SW CT and southern Westchester shoreline. Elsewhere,
tide levels should remain below minor benchmarks. If water levels
end up a bit higher, then additional statements and/or advisories
may be needed for Saturday night across the Western Long Island
Sound across NW Long Island and possibly along the Great South Bay
and upper Harbor.
Easterly swells will likely result in a sweep of 4 to 6 ft surf
tonight into Saturday, causing some minor beach erosion issues.
Dune impacts look localized and limited to minor.
There is a high risk of rip currents at Atlantic Ocean Beaches
through Sunday.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Coastal Flood Advisory until 4 AM EDT Saturday for CTZ009-010.
Coastal Flood Advisory from 1 AM to 5 AM EDT Sunday for CTZ009.
NY...Coastal Flood Advisory until 1 AM EDT Saturday for NYZ074.
Coastal Flood Advisory from 10 PM Saturday to 2 AM EDT Sunday
for NYZ074.
Coastal Flood Advisory until 4 AM EDT Saturday for NYZ071-073-
078-176-177.
Coastal Flood Advisory from 1 AM to 5 AM EDT Sunday for NYZ071.
High Rip Current Risk through Sunday evening for NYZ075-080-
081-178-179.
Coastal Flood Advisory until 2 AM EDT Sunday for NYZ075-178-
179.
NJ...Coastal Flood Advisory until 1 AM EDT Saturday for NJZ006-106-
108.
Coastal Flood Advisory from 10 PM Saturday to 2 AM EDT Sunday
for NJZ006-106-108.
MARINE...Gale Warning until noon EDT Saturday for ANZ331-332-340-345.
Small Craft Advisory until 6 AM EDT Saturday for ANZ335-338.
Gale Warning from 6 AM to noon EDT Saturday for ANZ335-338.
Gale Warning until 6 PM EDT Saturday for ANZ350-353-355.
&&
$$
SYNOPSIS...DBR/DS
NEAR TERM...DBR/DS
SHORT TERM...DBR
LONG TERM...DS
AVIATION...BG
MARINE...DBR/DS
HYDROLOGY...DBR/DS
TIDES/COASTAL FLOODING...DS
Area Forecast Discussion
National Weather Service Phoenix AZ
250 PM MST Fri May 28 2021
.UPDATE...Updated Fire Weather Discussion.
&&
.SYNOPSIS...
Seasonable dry and warm conditions under clear to mostly clear skies
are expected across the lower deserts through at least early next
week. High temperatures will mostly top out in a 99-102 degree
range through the holiday weekend with readings likely a bit
warmer for the middle of next week. A slight increase in moisture
mostly across eastern Arizona for next week may be enough for some
isolated mainly high terrain thunderstorms by early next week and
into the weekend. In addition, an isolated shower or thunderstorm
can not be entirely ruled out for the Phoenix area deserts for
much of next week.
&&
.DISCUSSION...
Yesterday marked the 7th consecutive day of mostly below normal, or
equal to normal, high temperatures for Phoenix with a high of 99
degrees. That trend should end today as with an above normal high of
102 degrees forecast for Phoenix, which would be 3 degrees above the
normal high of 99.
The early afternoon upper level RAP mesoscale analysis indicates a
dry westerly H5 flow aloft on the SW flank of a ridge to the east.
There was also a weak, dry UL trough and associated weak PVA
anomaly crossing the area with the main trough pushing into
central Canada. Clear to mostly clear skies were also noted across
our region with a large ridge positioned over the NE PAC. Mid-
level WV imagery also showed a swath of slightly elevated moisture
entering the region through SE CA.
A warming trend will continue today with highs topping out in
Phoenix and the lower deserts in the 99-102 degree range.
Models then agree on dry southwesterly flow with flattened ridging
into tomorrow with a weak mostly-dry positively tilted low pressure
system dropping from southern CA to over the N GOC-NW MX just SW
of the region from Saturday into Monday. As as result expect
highs in a fairly narrow range through the period. Highs will
climb to near 100-102 degrees for Saturday with the weak low
allowing for a very slight dip in temps with highs near 99-101 for
Sunday and Memorial Day Monday.
The Clusters forecast analysis shows the strong W US ridge now
actually peaking in strength on Wednesday and beginning to shift
east and weakening on Thursday and Friday. There are also hints of
weak troughing lingering to the southwest on Friday. For QPF chances
for Wednesday through Friday the Clusters show at least one minor
cluster favoring very minor QPF each day which would be associated
with very isolated showers or high-based thunderstorms. Better
shower and storm chances would be favored across the higher
terrain areas north and east of Globe as well as SE-NE AZ.
However the much more likely and bullish solution favored by the
Clusters is dry conditions associated with the strong midweek high
pressure building in from the northwest and associated mid-week warm
up to near 102-104 degrees on Wednesday and Thursday. Still, on
the GEFS plume PW moisture gradually increases from near 0.6
Monday to around 0.8 late in the week associated with the weak
troughing thats possibly lingering to the South or southwest.
The end result are very low-end POPs for Phoenix for much of the
week and into next weekend.
The latest indications are that the midweek warm-up resulting in
areas of moderate heat risk could possibly be reigned in by
increasing moisture and decreasing high pressure during Thu and
Fri which would mitigate an excessive heat event as temperatures
settle back to near 100-102 late this week and into the weekend.
However, out west the late week temperature could be a few
degrees warmer at around 103 to 105 degrees.
&&
.AVIATION...Updated at 1808Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No significant impacts to aviation through the TAF package. Winds
will favor normal diurnal trends with a switch to west-
southwesterly across the valley between 19-21Z. Speeds will be
generally light this afternoon, however, can`t rule out a few
thermal gusts reaching into the 14-18kt range, especially KPHX &
KDVT. A return to easterly flow during the overnight hours before
the typical switchback to westerly tomorrow afternoon. SKC to
start, transitioning to a FEW250 deck around sunset and eventually
going SCT250 by early morning.
Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns anticipated through the TAF
period. Wind directions will follow typical diurnal trends. At
KIPL, expecting a few hours of southerly winds with gusts to 15kts
before subsiding around 04Z. KBLH will see slightly higher gusts
to 20kts out of the south for several hours between 21-02Z before
tapering off for the overnight period. Skies will start off
generally clear, but a FEW deck AOA 250 will move ohd by later
this afternoon before becoming SCT250 overnight.
&&
.FIRE WEATHER...
Monday through Friday:
Weak upper level troughing will settle in over the region Sunday
into Monday with high pressure increasing by Wed, however max
temps will remain slightly above normal through the entire period.
A gradual increase in moisture during the period is likely to
bring some isolated thunderstorms across the AZ high terrain, with
lower desert storms not entirely out of the question though much
less likely. However, wetting rains are not very likely, so these
isolated storms may pose a dry lightning threat. Min RH values
will remain quite low, mostly staying between 5-10% each day.
Daily max RHs will mostly range from 20-30% with higher readings
across the western deserts. Winds will remain fairly light through
the bulk of the period, but with typical afternoon breeziness
most days.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Sawtelle
AVIATION...D`Anthony/Feldkircher
FIRE WEATHER...Sawtelle/Kuhlman
Area Forecast Discussion
National Weather Service Pueblo CO
310 PM MDT Fri May 28 2021
.SHORT TERM...(This evening through Saturday)
Issued at 305 PM MDT Fri May 28 2021
Currently...satellite imagery and radar show isolated thunderstorms
developing off the southern Sangre de Cristo range, east into the
Raton Mesa this afternoon. Satellite imagery also shows robust
cumulus fields over the Mountains, and into the Pikes Peak region. A
few weak radar returns are showing up near Pikes Peak. Temperatures
have warmed nicely, with 70s to mid 80s across the region. Winds
are southeasterly across the Plains, which has help keep moisture
pooled up there. Dewpoints are currently running in the upper 40s
to lower 50s.
Rest of today...thunderstorms are expected to remain confined to
near the New Mexico border this afternoon. CAPE values are rather
high across this area, at around 1500 j/kg. Shear is weak and
westerly. The potential exists for storms to become near severe
off the Raton Mesa over Las Animas County. Hail could briefly
approach one inch in diameter and wind gusts near 60 mph are
possible with stronger storms. Elsewhere, storms are expected to
remain sub-severe at this time, with gusty outflow wind to near
50 mph, especially over the Pikes Peak region.
Tonight...thunderstorms along the New Mexico border should dissipate
and track southeastward this evening with the loss of day time
heating. Up north, any cells that develop will also quickly
dissipate this evening. Dry conditions are expected overnight. At
the surface, lee cyclogenesis is forecast to strengthen across the
Plains, which will draw deeper moisture northward across the Plains.
Dewpoints are forecast to remain in the 50s with southeasterly flow
level flow. This will help keep temperatures mild, with lows in the
mid to upper 50s. The san Luis Valley is expected to fall into the
upper 30s to lower 40s.
Saturday...severe weather is looking likely across the Plains. Upper
level shortwave ridging is forecast to shift across Colorado and
into western Kansas through the afternoon. A strong embedded upper
disturbance will also shift east under the ridge by the afternoon.
At the surface, the lee cyclone is forecast to strengthen and shift
northeastward throughout the day. Currently, there is a bit of
uncertainty as to where the cyclone will set up; a few CAM solutions
have the low near Pueblo, while a fe have it up near Limon.
Currently prefer the more southerly solutions given the majority of
high-res guidance follows this, as well as the coarser resolution
models. Low level southerly flow will continue to pull moisture
northward across the Plains. Dewpoints are forecast to remain
steady or rise slightly into the upper 50s across the far Eastern
Plains by afternoon. MLCAPE values are forecast to rise in excess
of 1500 j/kg by early afternoon. 0-6 km shear is also forecast to
strengthen to near 35 kts by early afternoon. With the more
southerly surface low track, low level winds should draw more
easterly along and north of Highway 50. Expect thunderstorms to
develop from the Palmer Divide, southeast toward Baca County by mid
afternoon. Given the parameters, large hail, to 2 inches in
diameter, strong winds in excess of 60 mph and locally heavy
rainfall will also be possible. Areas along and north of Highway
50s, from Pueblo, southeast towards Springfield, will have the best
wind profiles for rotating updrafts. Given the east to southeast
surface winds, this area may also see the greatest potential for a
tornado or two during the afternoon. Mozley
.LONG TERM...(Saturday night through Friday)
Issued at 305 PM MDT Fri May 28 2021
...Scattered strong to severe thunderstorms possible throughout the
late hours of the evening over the eastern plains. Large hail of up
to 2" in diameter, along with strong and gusty winds of 70 mph or
greater, and even a few isolated tornadoes are possible with some of
these storms. There will still be a slight chance of severe
thunderstorms for Saturday night as well...
Saturday evening through Sunday morning...
The region will be under a ridge with troughing beginning to take
shape upstream over California, which will help to advect moisture
in the mid to upper levels from the southwest over Colorado.
Meanwhile downstream, a low located to the northeast over southern
Canada and a trough to the southeast over the deep south will result
in splitting and diffluence aloft over the area, and therefore the
atmosphere will become primed for possible strong to severe
thunderstorm development later in the day and into the evening,
especially over the eastern plains, once the capping deteriorates.
CAPE values will be the highest right around 00Z over the counties
of Bent and western Kiowa, with some models showing values of most
unstable CAPE close to 4000 J/kg and LI values of -8, therefore
there could potentially be severe thunderstorms over these
locations. Helicity values do appear to be very low so the biggest
threat would be large hail and strong winds accompanying these
storms, although with some models displaying high bulk shear values
of 60 to 70 kts, and the NAM12 producing high SIG TOR parameter
values of around 2, so a few isolated tornadoes cannot be ruled out.
Most likely area for these to occur would be over the eastern plains
and up to the Kansas border up until around 03Z on Sunday. Soundings
do indicate that there is a pretty good inverted V with skinny CAPE,
so the potential also exists that there could be some very strong
downdrafts and microbursts could become a hazard as well. The HRRR
is picking up on a possible MCV developing over Las Animas around
00Z, and then producing a very strong outflow of possibly greater
than 60 kts (69 mph), which could be affecting the counties of Baca,
Bent, and Otero to the north. Some strong storms could also develop
over the Sangre de Cristo and Wet Mountains, as well as the Rampart
Range earlier in the afternoon around 19Z, and these could become
severe as well as they move out over the plains along the I-25
corridor. Most of the stronger to severe thunderstorms should begin
to weaken after around 9pm as the environment begins to stabilize
more with the absence of surface heating, however, the risk of
thunderstorms will continue throughout the night with enough
diffluence aloft still in place and cyclogenesis taking place over
southeastern Colorado. Skies will remain mostly cloudy overnight.
Winds will generally be light and variable for most locations,
although with they will begin to increase during the evening over
the eastern plains and become strong and gusty out of the south,
then shifting more SE and weakening by early Sunday morning. High
temperatures on Saturday will be fairly mild for most locations
until clouds increase, and then fall to right around the seasonal
average for perhaps slightly above with such an extensive cloud
cover over much of the CWA.
Sunday afternoon through Monday night...
As the cyclogenesis continues with the low propagating a little
further south over NE New Mexico, it will begin to usher in more
moisture that will be wrapped around on the backside of the
deformation zone, right over much of the plains and overrunning
occuring as far west as the San Juan Mountains, therefore it looks
to be very possible that most of the CWA will experience periods of
rainshowers with embedded thunderstorms throughout much of the day
on Sunday, especially later in the afternoon and evening hours.
Lower levels will become more saturated with higher dewpoints
extending westward up to the I-25 corridor, with a dryline setting
up to the south and east and the forcing could allow for a better
chance of thunderstorms along this boundary as well. Most of the
instability will have shifted back to the western CWA and there
could potentially be some strong to severe thunderstorms over the
central mountains later in the afternoon as forcing and lapse rates
appear to be more favorable in these areas. Main threat for this
reason will be flooding over the burn scars potentially, especially
if some of these storms become stationary. On Monday, the very
positively tilted axis in the long wave trough over the southwestern
US is going to cause the low to become cutoff south of California,
which will help to keep the surface low remaining in place over New
Mexico into Monday, and this will allow for a very similar setup for
more continuous showers and thunderstorms possible over much of the
CWA. There will be cooler temperatures advected in from the north
over the plains, so this, along with extensive could coverage, will
keep max temperatures well below the seasonal average, by as much as
25 degrees in some locations. This cooler air at the surface could
also help to enhance overrunning, yet the lower levels will also be
much more stable and therefore most of the showery precipitation
will be on the light side, and continue throughout the night. Also,
with snow levels dropping on Monday as colder air moves in, peaks
above 10,500 feet could get anywhere from a dusting to a few inches
of new snowfall. Lows for Monday night will be cooler as well, and
slightly below the seasonal average for most locations, from the 40s
over the plains, to the upper 20s and 30s for high country.
Tuesday through Wednesday...
The surface low will begin to exit the region by early Tuesday
morning and allow for clearing to finally take place for most
locations throughout the morning. Afternoon thunderstorms will
develop later in the day over the mountains with some residual
moisture and the long wave trough axis still overhead. The U/L
cutoff low over the southwest will eventually detach itself from the
trough and allow it to begin to fill and shift further eastward on
Wednesday, although with a jet maxima upstream over the Dakotas, and
a sharply positive tilted axis, this will still put southeastern
Colorado in the divergent quadrant, so thunderstorms look to develop
over the mountains during the afternoon. The ECMWF is showing that
there could also be some convection over the far eastern plains in
the evening as a dryline sets ups from the trough right along the
Colorado/Kansas border, although the GFS keeps the boundary much
further south with a quicker propagation time of the trough moving
southeastward. So depending on which model holds true, will
determine if the far eastern plains possibly get strong to severe
thunderstorms later in the evening on Wednesday.
Thursday through Friday...
The deterministic models and ensembles are in fair good agreement
that a ridge will begin to build back in over the region with much
warmer temperatures returning, back to the seasonal average or even
slightly above for many locations. Due to there being enough
instability for the U/L cutoff low remaining off the coast of
southern California and feeding up a substantial amount of mid level
moisture from the south over the region due to this, there will
still exist the chance of afternoon and evening thunderstorm
development. Most of these storms will be confined to the
mountainous areas of the CWA, but some could develop over the plains
as well, especially on Thursday. Steward
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 305 PM MDT Fri May 28 2021
KALS...VFR conditions through the next 24 hours. A few
thunderstorms will remain possible over southern portions of the San
Luis Valley this afternoon, but confidence in one hitting the
terminal is low. Another round of afternoon thunderstorms is
possible Saturday.
KCOS...an isolated thunderstorm will remain possible through this
evening at the terminal. Southeasterly winds are expected into this
evening, becoming northerly overnight. More widespread
thunderstorms are forecast for Saturday afternoon, with reduced VIS
and CIGS expected.
KPUB...VFR conditions through Saturday morning. Winds are forecast
to be southeasterly this afternoon, and turn northerly overnight.
Widespread thunderstorms are forecast for Saturday with reduced VIS
and CIGS expected. Mozley
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MOZLEY
LONG TERM...STEWARD
AVIATION...MOZLEY