Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/27/18
Area Forecast Discussion
National Weather Service Bismarck ND
1024 PM CDT Sat May 26 2018
.UPDATE...
Issued at 1021 PM CDT Sat May 26 2018
POPs were again scaled back a bit as there has been little
development east of the main convection across eastern Montana
thus far. High res models though continue to advertise development
into western ND 03-05Z. Severe Thunderstorm Watch 122 continues.
UPDATE
Issued at 836 PM CDT Sat May 26 2018
Thunderstorm activity remains over eastern Montana, and appears to
be 1-2 hours yet before far western ND will see any of this
activity based on latest high res model output. Thus delayed
bringing convection across the MT/ND border until closer to
03-04Z. Latest HRRR and other high res models also continue to
develop convection across northern SD and into my south central
and perhaps my southeast after 05Z, as the low level jet develops
from the central high plains north-northeast across
western/central SD into my the southern half of ND.
UPDATE
Issued at 704 PM CDT Sat May 26 2018
SPC went with a severe t-storm watch for most of western North
Dakota now through early Sunday morning. Drier air across
northwestern ND kept the watch south of the Missouri River, which
high res CAMs support. The question is then what materializes
later this evening as the area of storms move into central ND.
There is some potential for an MCS/linear line developing and
turning southeast, impacting south central ND later this evening
and overnight as a strong low level jet develops across the
central Dakotas. A possible eastward expansion of the watch is
thus possible and will be monitored over the next several hours.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 214 PM CDT Sat May 26 2018
Main highlight is the transition from dry conditions this
afternoon to an increasing threat for showers/thunderstorms
overnight. Severe weather with large hail and damaging winds
remains possible favoring western North Dakota tonight.
Mid/upper level ridge will shift from western ND this afternoon
into eastern ND by 12z Sunday. Per water vapor loop, an upper
level low circulating over north central Nevada will slowly
translate north and east and into North Dakota Tuesday/Tuesday
night. Several shortwaves will eject out from this main low until
early next week. A couple shortwaves tonight traversing from south
central Montana into western North Dakota will result in the
development of showers/thunderstorms. CAM`s show discrete cells
developing in eastern Montana this evening (00z-03z), from Miles
City to Glasgow, gradually morphing into a larger area after 03z.
There appears to be a broken line of thunderstorms embedded within
the main area that will enter western ND between 03z-06z Sunday.
SPC continues with a slight risk for severe thunderstorms with
large hail and damaging winds, especially western North Dakota.
Further expansion and strength of the convection after midnight
will be tied to the low level jet and moisture advection into
central ND. For most of tonight, cloud bases will remain high
across central ND, closer to the ridge axis; while lowering across
the far west closest to the highest instability and approaching
shortwaves and associated showers and thunderstorms mentioned
above. Thus wind and hail are the primary threats. There will be
a window of opportunity between 06z-12z Sunday that with an
increasing low level southerly jet, moisture advection and
elevated instability will lead to additional development of
showers and thunderstorms for central ND late tonight through
sunrise Sunday.
Lingering convection early morning Sunday should wane in coverage
during the day. then ramp back up Sunday evening/Sunday night,
with the approach of the next mid level low.
.LONG TERM...(Sunday night through Saturday)
Issued at 214 PM CDT Sat May 26 2018
Periods of showers and thunderstorms, some severe per SPC remain
in the forecast Sunday night through Monday night. A deeper
southerly flow/moisture ensues as the main upper low from Nevada
approaches. Instability and shear remain in place for severe
weather especially central and southern North Dakota. A brief
break in the showers/thunderstorms Wednesday as the upper low
departs. Then southwesterly flow initiates again for more chances
of showers/thunderstorms Friday and Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 704 PM CDT Sat May 26 2018
An area of showers and thunderstorms will shift from eastern
Montana this evening and into western North Dakota between
02z-05z this evening. KISN and KDIK have the highest chance and
confidence for showers/thunderstorms. KMOT and KBIS will then see
chances overnight, after 06Z. Would anticipate some chances for
severe weather this evening from 02-05Z for KDIK and KISN. Cloud
bases will initially be high as showers/storms develop (9kft to
10kft), then lower with time towards 12z, but still remaining
VFR.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NH
SHORT TERM...KS
LONG TERM...KS
AVIATION...NH
Area Forecast Discussion
National Weather Service Brownsville TX
643 PM CDT Sat May 26 2018
.DISCUSSION...Updated for latest aviation discussion below.
&&
.AVIATION...VFR expected to predominate at the RGV terminals for
the next 24 hours. High-pressure ridging upstream will continue to
shift closer, further drying out the atmospheric column. RAP
BUFKIT soundings suggest that an MVFR-level cloud deck will form
tonight, but other guidance leaning away from it. Will retain FEW-
SCT 015 in TAF`s but not go with a prevailing CIG due to lower
confidence. Winds will generally be light SE-S, becoming more ESE
Sunday afternoon as the sea-breeze front progresses inland.
&&
.PREV DISCUSSION... /issued 321 PM CDT Sat May 26 2018/
..The HEAT of the moment...
SHORT TERM (Tonight through Sunday Night): Upstream ridging aloft
remains in place over west Texas and will shift slowly east toward
central Texas through the next day or two, further solidifying local
stability. A deep upper low will hover over the Southwest United
States during the short term, while in the GOMEX Subtropical Storm
Alberto moves north from the Yucatan Channel and across the Gulf
toward the north central to northeast Gulf coast during the next two
to three days. Across the west Gulf and the CWA, high pressure will
remain in control at the surface, with light to moderate southeast
to south winds and mostly clear skies. Temperatures will continue to
be above normal, particularly during the day, and the forecast will
feature high temperatures a couple of degrees above guidance. The
forecast values will dance around record numbers, with the 98 degs
forecast at Brownsville, the 100 degs forecast at Harlingen, and the
103 degs forecast at McAllen for Sunday comparing to 99, 100 and 107
degree records, respectively. These values will combine with ambient
humidity to produce mid afternoon heat index values of 103 to 108
degrees.
LONG TERM (Monday through Saturday): The heat that is already in
place builds further through the week, peaking on Wednesday and
Thursday as position and strength of the early onset of the 500 mb
"La Canicula" ridge centered from Coahuila through the Texas Big
Bend combines with lower surface pressures over west Texas...forced
a little bit by a slow moving 500 mb trough easing across the
intermountain west and into the U.S. Four Corners region by early
Friday. In my 10+ years tracking such overview parameters as 1000-
500 mb thickness and raw 850 mb temperatures, never have I seen a
587+ decameter value over McAllen and nearly 590 decameter (590!)
over the Rio Grande Plains (GFS). The ECMWF is just a hair behind,
and 850 mb temperatures *on the Rio Grande Plains* approach 28 or
29C (Wednesday). Combine this with deep dry air, near solstice
sun angle, and rapidly drying top soils and super-adiabatic
possibilities and it would not surprise to see 110+ for some areas
in southern Starr/Zapata Wednesday, perhaps beginning Tuesday and
continuing Thursday and perhaps beyond. The ridge shifts slowly
northward by next Friday/Saturday which raises surface pressures a
bit over west Texas and thereby slightly lowers the 1000-500 mb
thickness and 850 temperature, but not appreciably enough to put a
dent into this impressive late May and early June heat wave.
So, what does this all mean? First, given the parameters above, have
raised temperatures in all areas 2 to 5 degrees over previous
forecast, with 104 to 107 along and west of US 281 Tuesday through
Friday, only slightly lower on Memorial Day and next Saturday. The
good news (if you can call it that) is abundant dry air above the
few cumulus bases will mix down given expected mixing heights at or
above 8000 feet, so afternoon humidity in the 20s to lower 30s will
keep "feels like" temperatures close to the actual temperatures,
with perhaps an exception late next week/weekend across the more
populated RGV where near 110 apparent temperatures may start to
appear.
The aforementioned lowering surface pressures over west Texas will
help enhance the afternoon sea breeze, which will gradually progress
from near the coast into the mid/upper Valley by late afternoon and
bring slight cooling after the highs are reached. Until then,
however, 10 mph or lower winds will keep ventilation low. Bottom
line? A pretty remarkable, searing heat wave more similar to July
2009 and 2015-2017 than the end of May and start of June.
One final but important item: The impact of Alberto on Lower Texas
shoreline. This afternoon`s "jump" reformation of the center and
latest model trends suggest a far eastern Gulf of Mexico track in
the short term, before some "curling" into the upper low that
captures the system on Memorial Day. With the most strengthening
expected after the center passes our latitude, and landfall
somewhere closer to the western Florida panhandle than Louisiana,
swell impacts may be a bit more limited. While there should be some
tidal run up peaking at high tide Monday morning, it may only be
half to two thirds to the dune line at narrow beaches, more a
curiosity than anything else. Rip currents, however, which are
already at moderate levels may amp up a tad and due to the huge
crowds on a hot Memorial Day weekend a Rip Current Statement may be
needed this evening which could extend into Memorial Day.
MARINE (Tonight through Sunday Night)...Light to moderate
southeast to south winds and low to moderate seas will continue
along the lower Texas coast due to a persistent weak local
pressure gradient over the northwest Gulf. Subtropical Storm
Alberto will move north from the Yucatan Channel toward the north
central to northeast Gulf coast over the next couple of days,
posing no threat to the lower Texas coast.
(Monday through Thursday Night)...Based on the eastward nudging
of the new center for Alberto, landfall Monday will likely be a
bit farther east as well (and sooner) hence there may not be ample
time for significant swell to generate seas any higher than 4
feet. Blended close to TAFB in the offshore waters on Monday
before whatever enhancements come from Alberto recede.
Thereafter, gradient picks up a bit by Tuesday and especially
Wednesday and Thursday, but mainly the typical diurnal marine layer
arguments for the Gulf. Could edge near Caution (15 to 20 knot)
territory Tuesday night through Thursday night bur for now kept just
below. Laguna Madre may well see caution afternoons with the
gradient enhanced by the sea breeze Tuesday through Thursday.
Otherwise, moderate seas over the Gulf with some increase in wind
waves, perhaps to 3 feet, are expected especially Wednesday night
on.
CLIMATE...Been flirting with records in recent days and the
expected heat of the atmosphere upcoming will challenge more. The
following are records for McAllen/Miller and Brownsville May 28
through 31:
McAllen/Miller
May 27 107 in 1973
May 28 101 in 2017
May 29 102 in 1975
May 30 103 in 2004
May 31 106 in 1967
Brownsville
May 27 99 in 1973
May 28 98 in 1919
May 29 98 in 1922
May 30 100 in 1919
May 31 100 in 2005
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
This product is also available on the web at:
HTTP://WEATHER.GOV/RGV
53-Schroeder/65
Area Forecast Discussion
National Weather Service Charleston SC
1023 PM EDT Sat May 26 2018
.SYNOPSIS...
Deep tropical moisture on the east side of Tropical Cyclone
Alberto will spread into the region on Sunday. This moist
airmass will linger across the area into the middle of next
week, resulting in unsettled weather.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 1020 PM: I will issue a quick update to adjust sky and
temperatures to observations.
As of 920 PM: KCLX only detected isolated showers across the
coastal areas this evening. However, the showers have generally
tracked inland and dissipated. I will keep the forecast free of
mentionable PoPs.
18Z run of the GFS and SREF, suggests that the potential for
heavy rainfall late Sunday into early Monday is increasing.
Overall there has been a eastward shift in the track of Tropical
Cyclone Alberto. Southeast GA/SC will be positioned between the
closed mid level over the Gulf of Mexico and a ridge across NC.
Late Sunday night, the core of the H25 jet pushes south across
the Mid Atlantic states. At the sfc, a trough is expected to
rotate northward on the east side of Alberto, reaching the GA/SC
coast late Sunday evening. The placement of the mid level
heights, jet, and the sfc trough will favor the development of a
Predecessor Rainfall Event (PRE). GFS and ECMWF indicate that a
wide band of heavy showers, possibly embedded thunderstorms,
will develop offshore Sunday evening, moving across the CWA
Sunday night into early Monday morning. SREF normalized anomaly
is interesting as it shows a 3 sigma signal in PW passing over
the CWA between 6Z to 12Z Monday. It is possible that the heavy
rainfall could overlap with the high tide at 8 PM Sunday and 8
AM Monday.
As of 740 PM: KCLX indicated little to no coverage of showers
across the forecast area. I will update the forecast to remove
mention of thunderstorms and lower PoPs below mentionable values
over the next hour.
As of 6 PM: Visible satellite indicates that earlier cool pools
have drifted inland. In the wake, shallow Cu has developed over
the CWA, only a few showers over Jenkins and Screven Counties.
HRRR indicates that little to no coverage will redevelop through
the rest of this evening and during the overnight hours. I will
update the forecast to decrease PoPs, reduce thunder mention to
isolated, and indicate on light intensity.
Previous Discussion:
Until Sunset: Showers and isolated thunderstorms continue to
move inland with the sea breeze, decreasing in both intensity
and coverage. This is because SPC mesoscale analysis now indicates
MLCAPEs ~1,000 J/kg inland. We adjusted POPs down slightly for
the next few hours to account for this. But it`s possible POPs
may remain a little too high for a little too long inland. Also,
attempted to again adjust the hourly temperatures to better
reflect the current observations and the progression of the
showers with the sea breeze inland.
Tonight: Models are fairly consistent showing a period of dry
weather this evening into most of the overnight. Models even
hint at some stratus or fog well inland. But confidence was not
high enough to include this in the forecast. Deep tropical
moisture associated with an approaching Alberto will move in
from the south late tonight. PWATs are forecasted to exceed 2",
which is 2 standard deviations above normal for this time of
year per NAEFS. We have POPs increasing from south to north late,
especially around daybreak. Lows will be mild due to mostly
cloudy skies, ranging from the upper 60s to lower 70s.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
Sunday through Monday: There is no change with this forecast package
to the overall setup for this time period. Deep tropical moisture,
with precipitable water values in the 2.25-2.50 inch range, will
spread northward into the forecast area through the day on Sunday
around the broader circulation of Tropical Cyclone Alberto. Rain
chances will steadily increase Sunday into Sunday night, and chances
are currently in the 80-90 percent range. Upper jet dynamics will
provide larger scale forcing in the presence of the tropical
moisture feed, and widespread moderate to occasionally heavy rain is
expected just about everywhere. The main tweak to the forecast is to
account for slightly faster timing, based on model consensus and the
National Hurricane Center forecast track for Alberto. Rainfall
amounts are expected to range 1-3 inches through Monday, with the
highest amounts progged for the Charleston Tri-County region. The
threat for localized flooding issues remains, with the heaviest
period of rain occurring Sunday evening through early Monday
morning.
Tuesday: Alberto is forecast to pass well west of the forecast area
on Tuesday. A very moist airmass will remain in place, and numerous
to widespread showers and thunderstorms are expected to develop.
This activity will be more diurnally driven, beginning quickly in
the morning with the onset of heating. The overall severe threat
will remain low through the short term period.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Active weather will persist through the middle-to-end of the week as
deep tropical moisture remains in place. The lack of any larger
scale forcing will result in a primarily diurnal trend for the POP
forecast, with chance-to-likely most days and low-end-to-slight
chance overnight. The flooding threat will decrease, though local
issues cannot be ruled out given the ample moisture available to
storms mainly Wednesday and Thursday afternoons.
High pressure centered near the Bahamas will slowly assume control
of the local pattern as we head into next weekend, bringing more
settled conditions. Temps will trend from near to marginally above
normal through the period.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Prior to the 0Z TAFs, KCLX indicated little to no coverage of
showers across the forecast area. The terminals remained dry
through this afternoon. Conditions across the KCHS and KSAV are
forecast to remain VFR through tonight. After sunrise Sunday,
sfc ridge will lift north as a trough ripples north across GA. A
large broken band of showers and isolated thunderstorms is
expected to develop within the trough. MVFR ceilings and periods
of MVFR visibilities will likely occur with the moderate
showers. I time MVFR conditions to arrive at KSAV at 14Z and
KCHS at 16Z.
Extended Aviation Outlook: Occasional to frequent ceiling and/or
visibility restrictions can be expected at the terminals Sunday
evening through Monday morning as an area of moderate to heavy
rainfall crosses the area. VFR conditions will prevail thereafter,
though continued unsettled conditions mean that brief periods of
flight restrictions in showers and thunderstorms are possible mainly
in the afternoons.
&&
.MARINE...
Tonight: Offshore buoys and stations along the coast continue
to report winds of 10-15 kt associated with the inland moving
sea breeze and a slightly enhanced pressure gradient. Winds
should remain this intensity overnight. Seas will range from
2-4 ft, highest beyond 20 NM offshore.
Sunday through Thursday: Winds will start out easterly or
southeasterly on Sunday, but will gradually become more southerly
into Monday as Alberto moves closer to the Gulf Coast. Southerly
flow will then prevail into mid week. Speeds will generally top out
in the 15-20 knot range at their strongest, staying mainly in the 10-
15 knot range. The main concern will be seas which will increase
Sunday and Sunday night. For the outer waters beyond 20 nm, 6 foot
seas are expected by the afternoon and could even get inside of 20
nm. A Small Craft Advisory will likely be needed for at least the
outer waters Sunday afternoon into Monday. Seas will return to the 2
to 4 foot range with moderate southwest winds mid-week as high
pressure near the Bahamas takes control.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...NED
SHORT TERM...
LONG TERM...CEB
AVIATION...NED
MARINE...
Area Forecast Discussion
National Weather Service Grand Forks ND
1026 PM CDT Sat May 26 2018
.UPDATE...
Issued at 1026 PM CDT Sat May 26 2018
Regarding thunderstorm potential tonight: Thunderstorm activity
over Eastern Montana is shown to spread eastward, with a general
agreement in CAMs of arrival in our far western CWA after 7Z, and
the Red River Valley around 12Z. This may be optimistic on timing
based on current regional radar trends. Evolution and intensity
are still uncertain, and there is not a lot of agreement on that
side of things at this point. RAP shows MU CAPE potentially in the
1500-2000 J/KG range in our far west by 12Z as warm front moves
northward and southerly flow begins to develop, while values
remain lower to northeast. At the very least keeping thunder in
the forecast and adjusting timing of PoPs seemed reasonable. Any
thunderstorms would become elevated and if low levels remain
decoupled it will be hard to anticipate potential for any severe
wind. Also, if activity outpaces increase in instability stronger
updrafts necessary for larger hail may not be supported. Potential
is there and this should be monitored, but overall confidence in
impacts is low.
UPDATE Issued at 645 PM CDT Sat May 26 2018
Only minor adjustments to near term trends, otherwise monitoring
upstream activity for possible adjustments to PoP/Wx for later
tonight/tomorrow. Elevated instability (MU CAPE 500-1500 J/KG)
should be in place so while PoPs weren`t adjusted, I added thunder
mention to late night/Sun morning grids.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 246 PM CDT Sat May 26 2018
Mostly sunny skies are expected through the remainder of the day
across much of the forecast area. The only exception will be
across north and northwest Minnesota where a persistent cumulus
field has developed in a less stable airmass influenced by a weak
upper level shortwave north of the Great Lakes region. Slight
instability of 500-1000 J/kg MUCAPE in this region may allow for
an isolated thunderstorm or two in this region later this evening.
Otherwise, a few clouds and breezy conditions will persist across
eastern ND/western MN. Winds are expected to gradually diminish
through the evening and overnight hours as surface high pressure
shifts to the east.
Rain chances will increase across eastern ND early Sunday morning
as precipitation associated with a subtle mid level wave propagate
into the region around an upper level ridge axis. This early
morning precipitation is expected to move out of the region and
make way for a second round of showers/thunderstorms Sunday
afternoon. A deepening surface low across central SD will cause a
northward flux of higher theta-E air into the southeast ND/west MN
region. Deterministic and short- range ensemble guidance suggest
a boundary layer airmass characterized by dewpoints in the upper
50s/low 60s will support moderate instability of 1.5-2.5 kJ/kg
MLCAPE by the afternoon and evening hours. 0-6 km Bulk Shear
values of 30-40 knots will support organized convection that will
pose a threat for severe hail up to one inch and strong wind gusts
up to 60 mph. While convection will likely be focused a surface
warm front across the southern River Valley, uncertainty remains
as to the degree of destabilization from daytime heating due to
early morning showers/cloud cover and whether forcing along the
front will be sufficient to initiate convection. As such,
trends in surface dewpoints and cloud cover will have to be
monitored to assess the afternoon severe potential.
.LONG TERM...(Sunday night through Saturday)
Issued at 246 PM CDT Sat May 26 2018
Temperatures... Hot weather continues Monday for the Memorial Day
Holiday. Cooler temperatures begin to move in Monday with 70s and
the low 80s in the Devils Lake Basin and along the international
border. Cooler weather moves across of the rest of eastern North
Dakota and northwest Minnesota Tuesday with temperatures still above
normal but not like the recent record setting temperatures. By late
next week temperatures could even to fall to close to normal as a
cooler air mass moves in.
Thunderstorm Potential... Thunderstorms and showers on Monday with
potential for strong to severe storms. This will depend on what
happens Sunday as any significant convection on Sunday will reduce
the chance for strong to severe storms Monday. Bulk shear values on
Monday across eastern North Dakota and northwest Minnesota in the
NAM are in the 30 to 55 kt range which would support strong to
severe storms. What is more in question is the instability,
especially after potential Sunday convection. MU CAPE varies
significantly from near 0 up to 3500 J/kg, but in the areas with the
better shear values go up to closer to 2300 J/kg in the NAM and GFS.
Thunderstorms will again be possible Tuesday and Wednesday but it is
too early to say much about thunderstorm strength for those days.
Excessive Rainfall Potential... Monday into Wednesday high
precipitable water values in the NAM and GFS are above the 90th
percentile for nearby sounding climatologies (BIS, ABR, and INL).
This is supported by the previous upper low becoming dislodged and
the trough moving towards the Northern Plains. Dryer weather
expected Thursday before another chance for rain Friday into
the next weekend as an upper level trough moves into the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 645 PM CDT Sat May 26 2018
VFR conditions should prevail through the TAF period, and gusty
northwest winds should decrease early in the TAF period. Southeast
winds increase during the day Sunday and a few gusts to 20kt can`t
be ruled out. Primary aviation concern will be potential for
showers/thunderstorms late tonight (after 08Z) through the
morning, and again in the late afternoon/evening. Confidence
wasn`t high enough to introduce more than VCSH at KDVL for now,
but will need to monitor trends as activity develops in eastern
Montana and western ND as this would be what may impact eastern ND
and northwest MN later tonight.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...DJR
SHORT TERM...AM
LONG TERM...NC
AVIATION...DJR
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
922 PM EDT Sat May 26 2018
.SYNOPSIS...
A cold front will move south of the forecast area tonight. Cool high
pressure will build in from the northeast on Sunday and will hold
over the region into Monday with plenty of clouds expected. High
pressure will shift east late Monday and Monday night as a weak warm
front approaches from the west. A cold front will drop south through
the region by Tuesday morning. High pressure will build over the
region Tuesday and will push offshore south of New England
Wednesday. Low pressure may bring appreciable rainfall to the region
Friday into the weekend.
&&
.NEAR TERM /THROUGH SUNDAY/...
925 PM Update... Minor changes to the forecast based on trends
in the forecast database.
825 Update...So minor changes to the forecast to
indicate that showers will occur and may impact your way home.
Rain will occur but wont be a nuisance.
720 PM Update...Minor changes at this time. Convection is struggling
over southern NH and SW Maine. Some pockets of better instability
have helped better cells for a few scans...but overall these have
weakened with time. Will continue to monitor.
Previous discussion...Slow moving backdoor front continues to
shift southwest early this afternoon with most of the associated
shower activity still running from northern New Hampshire
through southwest Maine. To the south...filtered sun through
high clouds has boosted temps in the mid to upper 80s across
southern New Hampshire. This will be the area of concern through
early evening as the front continues to shift south into this
unstable air mass. SPC has upgraded this area to a marginal risk
for severe and radar showing convection beginning to fire over
eastern New York and central Vermont. HRRR showing this activity
becoming more organized as it moves into southern New Hampshire
later this afternoon and evening. SPC meso analysis page
showing CAPES edging into the 500 to 1000 range with moderate
shear. Have included heavy rain and gusty winds in the zones for
these areas but will hold off on enhanced wording to see how
the situation develops.
In any case...HRRR showing this activity pushing south of the
forecast area around 00Z with just light scattered showers in
its wake. Onshore flow sets up behind the front by late this
evening and expect ocean stratus to overspread much of southern
New Hampshire and extreme southwest Maine by midnight or shortly
after. Lows overnight will range through the 40s in northeast
zones and lower to mid 50s in the southwest.
&&
.SHORT TERM /SUNDAY NIGHT/...
High pressure will build in from the northeast on Sunday
increasing moist onshore gradient and keeping much of southern
New Hampshire and southwest Maine socked in with stratus.
Farther to the north and east looking for filtered sun through
high clouds. Looking for highs in the north and east to top out
in the lower to mid 60s. Coastal and southwest zones will only
see highs in the 50s.
High pressure will shift off to the east Sunday night allowing
low level moisture to overspread much of the forecast area
overnight. Looking for areas of fog and drizzle in southern
zones with the remainder of the forecast area remaining dry.
Lows will generally range through the 40s.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
High pres centered over the maritimes will continue to provide
a cool, moist onshore flow into Mon, especially on the coast.
Far interior locations such as southwestern NH will see warming
conditions as the cool low level air mass begins to depart. A
cold front will cross the region Monday night into early Tuesday
with the chance of showers, mainly across northern and central
zones. High pressure then builds in later Tuesday through
Thursday with warming temperatures expected. Not out of the
question that a few locations hit 90 on Thursday. Thereafter,
some beneficial rainfall is possible Friday into the weekend if
the remnants of Alberto do indeed make their way to the
northeastern states as several deterministic models are showing.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
Short Term...VFR with areas of MVFR/IFR ceilings developing in
southern New Hampshire and southwest Maine. This cloud cover
with persist through Sunday. IFR/LIFR ceilings overspread most
of the forecast area Sunday night.
Long Term...VFR to IFR conditions are likely on Monday, mainly
on the coastal plain where cool, moist onshore flow will
persist. Improving conditions are expected Tuesday morning
through Thursday where are return to VFR is expected.
&&
.MARINE...
Short Term...Have issued SCA`s for late tonight through midday
Sunday as easterly gradient tightens over the Gulf of Maine later
tonight.
Long Term...SCA due to seas over the outer waters possible
Monday, but at this time it looks marginal.
&&
.FIRE WEATHER...
Wind switches onshore this evening and overnight and remains
that way into Monday, so expect high RH through Monday, with
scattered showers and relatively light winds.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until noon EDT Sunday for ANZ150-152-154.
&&
$$
NEAR TERM...Hanes/Watson
SHORT TERM...Ekster/Sinsabaugh
LONG TERM...Ekster
Area Forecast Discussion
National Weather Service Huntsville AL
701 PM CDT Sat May 26 2018
.NEAR TERM...(Tonight)
Issued at 701 PM CDT Sat May 26 2018
Convection continues to make its final hurrah across the TN Valley
this evening, with just a few showers/storms of note on KHTX. The
trend will likely continue for the next hour or so, with only a rogue
shower/storm expected overnight. Unlike last night where we had
widespread rain and lingering stratus during the overnight/morning
hours, with convection being more sparse today, fog formation is
likely by sunrise. The fog will be more dense in locations that
received heavy rainfall this afternoon/evening, but have included the
chance for at least patchy fog area-wide in the grids. Will monitor
obs through midnight and will make updates as warranted to more
dense-wording in the official forecast (if need be).
Several changes were necessary for the update this evening as a
result of this thinking, with PoPs decreased and Sky grids updated as
well. The HRRR was doing a fairly good job with the coverage of
isolated/scattered convection at the moment, and so those Sky grids
were implemented for the rest of the evening/overnight hours. With
more clearing noted in the grids than before, this better supports
the thinking for fog formation (as opposed to 80-100% coverage from
before).
Temps are on track to bottom out in the upper 60s to around 70F again
for Sunday morning.
.SHORT TERM...(Sunday through Monday night)
Issued at 159 PM CDT Sat May 26 2018
A narrow mid to upper level ridge position builds into place north
of Alberto as the upper trough remains over the lower OH and MS
valleys on Sunday. The ridge gives way quickly during the afternoon
as the first of several spokes of vorticity rotate north and
northwest into the TN valley. By late in the day, expect numerous
showers and thunderstorms along this feature that will translate
northwest and west during the evening. A narrow dry gap behind this
band is quickly filled in by a potentially heavy band of showers and
thunderstorms late Sunday night into early Monday. Have carried the
highest PoP in our southeast (Likely), with chance further north. The
models have shown a sharp gradient to this particular rain band in
successive runs, making the PoP forecast challenging. It`s possible
that our TN counties may see very little from this band, while north
AL gets a period of heavy rain Monday morning. Then, this abruptly
diminishes and/or dissipates during day as a strong dry slot becomes
ingested north-northwestward into the circulation.
On Monday Night, depending on the track of Alberto either into
southwest AL or southeast MS, a compact precipitation area around
the circulation may affect parts of our area as early as late Monday
night. The best chance may be our southwest counties based on the 12Z
guidance.
.LONG TERM...(Tuesday through Friday)
Issued at 159 PM CDT Sat May 26 2018
As one would expect, some model discrepancies are noted with the
track of Alberto (or the remnants of Alberto) after it makes
landfall. The operational GFS/Euro track the system across the heart
of Alabama Tuesday and to near western Kentucky by early Wednesday.
The NAM is a bit faster and has more of a westward track, and is
supported by a large number of GEFS members. The official NHC track
is a blend of the two camps and that seems quite reasonable.
For now, that would place the highest potential QPF across western
Alabama Tuesday underneath the core/proximity of the lower. Depending
on the track as well some areas may be in the favorable right front
quadrant for rotating convective bands early Tuesday. Despite the low
lifting north of the Tennessee Valley by Wednesday, expect scattered
to numerous storms again especially in the afternoon with broad
troughiness and high PWATs in place.
Not much notable change on Thursday, and in fact we may see another
uptick in precipitation with the passage of an upper s/w trough
during the afternoon/evening hours. In general, have trended toward
the lower end of the diurnal ranges (warmer mins/lower maxes) given
the tropical airmass and likely early cumulus/convective initiation.
The upper flow becomes a bit more northwesterly by late in the work
week/toward next weekend as the upper ridge begins to build into the
Plains. The high amplitude nature of the ridge will bring potentially
extreme heat to the southern/central plains late next. Closer to
home, will continue chance pops for Friday/Saturday as there`s some
indications of another piece of northern stream energy working its
way across the Tennessee Valley during that time frame.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 630 PM CDT Sat May 26 2018
Current convection ongoing across the region continues to dissipate
as of the 00Z TAF issuance, and only an isolated shower/storm is
expected overnight. With that said, mention of VCSH/VCTS was removed
thru 27/01Z. Fog formation is likely overnight (compared to more
stratus coverage last night/this morning), so have retained the IFR
conds possible between 27/10-14Z at both KHSV and KMSL. Fog will
dissipate shortly after 14Z with VFR conds returning/prevailing thru
the end of the TAF period. Showers/storms will begin developing by
this time, so a VCTS was mentioned at both sites beginning at 27/17Z.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&
$$
NEAR TERM...12
SHORT TERM...17
LONG TERM...15
AVIATION...12
For more information please visit our website
at weather.gov/huntsville.
Area Forecast Discussion
National Weather Service Miami FL
900 PM EDT Sat May 26 2018
.AVIATION...
Trends in the model suggests more precipitation is possible
through the night into Sunday.
&&
.UPDATE...
Raised rain chances overnight to nearly 100 percent as nearly
certain widespread rain will continue. Latest convective band is
pushing into far southern Florida nearly 1z and additional banding
is likely toward early morning. 0z RAOB indicates increasingly
favorable airmass for rotating updrafts as supplemented by HRRR
and other CAMs. Target time for enhanced tornado risk appears to
be 5z-13z, so will be continuing to closely monitor. SPC continues
with Slight Risk of tornadoes and damaging winds south and west of
a Naples to Miami line overnight, with Marginal Risk for remainder
of CWA. Flood Watch and Small Craft Advisory continues areawide.
High Risk of Rip Currents on East coast through Monday, with High
Risk Sunday for Gulf Coast. Will be also monitoring for minor
tidal inundation along the Gulf coast Sunday, particularly around
high tide with is roughly midday. A Coastal Flood Statement is in
effect along the Gulf coast where a foot or so of inundation is
possible. Last but not least, Tropical Storm Warning in effect for
outer Gulf Waters, beyond 20 nm offshore. Latest observations from
buoys in the Gulf and also in and near the Keys should tropical
storm force wind gusts are likely already occurring in this area.
8PM NHC advisory on Subtropical Storm Alberto reveals weak,
disorganized storm with max. sustained winds of 40 mph, though
highest winds are present well east of the center. Alberto should
make its closest approach to South Florida during the morning
Sunday.
&&
.PREV DISCUSSION... /issued 349 PM EDT Sat May 26 2018/
DISCUSSION...
The National Hurricane Center shows Alberto continuing to move north-
northwestward over the eastern Gulf waters through the rest of the
weekend. At the same time, an area of high pressure continues to
remain over the western Atlantic just to the east of the Florida
peninsula. This set up will allow for a south southeasterly wind
flow to continue and it will keep a steady flow of deep tropical
moisture in place through the Memorial Day weekend.
With all of this moisture in place, rain chances will remain high
through the rest of the weekend. Of particular concern is that for
late tonight and Sunday, South Florida will lie under a region of
upper-level divergence to the east of the deepening mid/upper level
low pressure over the Gulf of Mexico associated with Alberto, as
well as increasing low-level convergence and wind fields around the
periphery of Alberto`s large-scale circulation. This synoptic setup
is conducive for bands of rain and a few embedded thunderstorms to
not only increase in coverage but also in intensity as they move
north across the area. The end result is that our flood threat will
increase beginning late tonight and continue through Sunday, and
possibly Sunday night as well. The Flood Watch will remain in place
at least through Sunday evening, and we will continue to closely
monitor the threat of heavy rain and flooding even into Monday as
Alberto continues to affect the northern Gulf coast.
Along with the increasing threat of flooding, the potential for
isolated tornadoes will increase late tonight in response to the
strengthening low-level wind profiles, helicity values and
increasing instability. The highest tornado threat appears to be
late tonight and Sunday over Southwest Florida, but notable as well
over Southeast Florida. This corresponds well with SPC`s marginal
risk area over all of South Florida.
Both of the latest GFS and ECMWF show Alberto moving across the
Southeastern portion of the country early next week. This should
also allow for a deep swath of moisture across South Florida as the
flow should remain out of the south southwest at least through the
middle of the week. By the end of next week, the swath of deeper
moisture should slowly move northward out of the region, which
should allow for a return to a more typical summertime pattern with
scattered showers and thunderstorms developing along the east and
west coast sea breezes.
MARINE...
The offshore Gulf waters are under a Tropical Storm Watch
through midday Sunday due to its closer proximity to the outer
tropical storm force wind field. Wind speeds will be between 25 and
30 knots across the Gulf waters, with higher gusts even outside of
any rain bands. Over the Atlantic waters, South-Southeast winds of
20 to 25 knots tonight and continuing through late Sunday. Wind
speeds gradually decrease to 15 to 20 knots late on Memorial Day,
except over the offshore Gulf waters where winds will remain around
20 knots.
A Small Craft Advisory will be in effect for all the coastal waters
through at least Sunday night.
BEACH FORECAST...
Tides have been running about a half-foot above normal along the
Southwest Florida coast based on data from NOAA tide gauges. As
Alberto moves northward over the eastern Gulf, consensus of the
latest model guidance shows that the water levels could go up a
little bit more, as much as 1.5 to 2 feet above mean higher high
water (MHHW) across portions of the Southwest Florida coast during
the high tide cycle Sunday morning through midday. This will
allow for the possibility of some minor coastal flooding and minor
beach erosion especially in the vulnerable areas along the
Collier County coast. We will continue to monitor this, however if
this trend continues, a coastal flood statement will need to be
considered for Sunday. There will be a high risk of rip currents
along the Atlantic Coast beaches through Sunday evening. The
threat for rip currents will also begin to increase late tonight
and Sunday along the Gulf coast beaches, probably to a high risk.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 73 83 75 84 / 90 90 60 90
Fort Lauderdale 75 82 77 83 / 90 90 70 80
Miami 74 83 75 84 / 90 90 70 80
Naples 72 84 74 85 / 90 80 60 80
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...Flood Watch through Sunday evening for FLZ063-066>075-168-
172>174.
High Rip Current Risk from 8 AM EDT Sunday through Monday
afternoon for FLZ069-075.
High Rip Current Risk through Monday afternoon for FLZ168-172-
173.
AM...Small Craft Advisory until 8 AM EDT Monday for AMZ610-630-650-
651-670-671.
GM...Tropical Storm Warning for GMZ676.
Small Craft Advisory until 8 AM EDT Monday for GMZ656-657.
&&
UPDATE...23/SK
DISCUSSION...55/CWC
MARINE...55/CWC
AVIATION...67/MT
BEACH FORECAST...55/CWC
Area Forecast Discussion
National Weather Service Melbourne FL
930 PM EDT Sat May 26 2018
...Flood Watch Remains in Effect for East Central Florida Over
the Holiday Weekend...
.UPDATE...
Tonight...Increasing low level southeast winds have moistened the
atmosphere back up after the brief dry intrusion from the east.
Areas of light rain and isolated showers have been spreading
northwest across the region. However, deep convection has remained
well to the south closer to Alberto. As the circulation lifts north
across the eastern Gulf of Mexico, moisture will increase further
across the local area, and outer bands should push towards our
southern counties. The HRRR model shows low level shear increasing
too, so will have to watch for rotating cells over the Atlantic and
near the Treasure Coast/Okeechobee in the pre-dawn hours. A threat
for heavy rain also exists with this band of convection. The HRRR
and GFS show widespread precip coverage southward from about Orlando
to Cape Canaveral.
Have increased PoPs a little across the south half (60-80%) based on
the latest model trends.
Previous Discussion...
Sun-Mon...Rain chances ramp up considerably Sunday (up to 90%) and
remain high Monday (70-80%) as deep southerly flow to the east of
Alberto transports a very moist tropical airmass with PW values of
2+ inches northward across the area.
Heavy rainfall and localized flooding remain the main concerns from
this system, with the potential for training bands of showers and
storms moving northward across the area. Rainfall totals of 2-3
inches are generally expected through Sun- Mon across much of the
area, with locally higher totals possible. A Flood Watch remains
in effect for all of east central Florida during this timeframe.
An isolated tornado threat will also exist across the region,
mainly into Sunday, when low level helicity values are maximized
to the east of Alberto. While wind threat continues to remain low
for the area with Alberto`s forecast track, breezy S/SE winds will
still be expected into Sunday, with stronger showers and storms
having the potential to produce strong wind gusts.
Cloudy to mostly cloudy skies will persist through the holiday
weekend, keeping highs limited to the low 80s on Sunday and mid 80s
on Memorial Day. Overnight lows will remain above normal with values
in the low to mid 70s.
Tue-Fri...Even as Alberto weakens after landfall along the northern
Gulf coast, a moist plume of 2+ inch PW values will persist in a
deep S/SW flow over the area. This will continue a wet pattern
through at least Wednesday, with likely rain chances (60-70%)
forecast across much of the region. Showers and storms will likely
transition to becoming more diurnally driven, with greatest coverage
in the afternoon each day. Into late week, models indicating a
slight decrease in rain chances as deeper moisture shifts south and
east. However, scattered shower and thunderstorm coverage will
remain in the forecast each afternoon. Highs will range from the
mid- upper 80s, with low 90s possible across portions of the area
on Friday.
&&
.AVIATION...
Much more adverse conditions are on tap as even higher moisture
associated with the circulation of Alberto advects into east central
Florida overnight and Sunday. Recent HRRR model runs show
widespread showers with MVFR-IFR conditions spreading to KSUA a
little after 06z, then rapidly northward and reaching KDAB-KLEE a
little after 12z. This is faster than shown by the most recent
TAFs, so further adjustments in timing can be expected due to the
very dynamic nature of convection around this developing tropical
cyclone. If the recent HRRR model pans out, there should be a
period of brief heating in the late morning and early afternoon,
which would allow for a second round of convection. It may not be
as widespread, but the HRRR shows wind gusts over 35 knots along the
coast and a fair amount of lightning.
&&
.MARINE...
Tonight-Sunday...Hazardous conditions for small craft operation.
Southeast-south winds will increase to 20-25 knots tonight and
Sunday. Seas will steadily build and be a choppy 6-8 feet offshore
and 5-6 feet near shore. In addition, widespread showers with
embedded squalls will affect the waters. Gusts over 35 knots will
occur with the squalls along with some lightning strikes.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...Flood Watch through Monday evening for Coastal Volusia County-
Indian River-Inland Volusia County-Martin-Northern Brevard
County-Northern Lake County-Okeechobee-Orange-Osceola-
Seminole-Southern Brevard County-Southern Lake County-St.
Lucie.
AM...Small Craft Advisory from 8 AM to 10 PM EDT Sunday for Flagler
Beach to Volusia-Brevard County Line 0-20 nm.
Small Craft Advisory from 8 AM Sunday to 8 AM EDT Monday for
Flagler Beach to Volusia-Brevard County Line 20-60 nm-
Volusia-Brevard County Line to Sebastian Inlet 0-20 nm.
Small Craft Advisory until 8 AM EDT Monday for Sebastian Inlet
to Jupiter Inlet 0-20 nm-Sebastian Inlet to Jupiter Inlet
20-60 nm-Volusia-Brevard County Line to Sebastian Inlet 20-
60 nm.
&&
$$
Lascody/Bragaw
Area Forecast Discussion
National Weather Service San Angelo TX
622 PM CDT Sat May 26 2018
.AVIATION...
/00Z TAFS/
Expect VFR conditions at the terminals tonight and Sunday.
21
&&
.PREV DISCUSSION... /issued 245 PM CDT Sat May 26 2018/
SHORT TERM...
(Tonight and Sunday)
This morning`s ARW and occasionally the HRRR have hinted at a few
storms across the southeast portions of the area this afternoon
and evening, in an area where visible satellite showed a little
bit of ACCAS this morning. Its also pretty close to the moisture
axis the storm last followed. Still think that convection is
unlikely, but hard to rule it out completely. Will add a mention
of isolated convection to areas southeast of a Brady to Menard to
Sonora line through sunset. Otherwise, hot and dry to continue.
Approaching the 100 degree mark in some areas this afternoon, and
all indications are that it will be hotter on Sunday. Lots of
locations to see highs in the 100 to 103 range.
LONG TERM...
(Monday through Saturday)
The main story going into the last week of May will continue to
the very hot temperatures. The upper level ridge remains centered
over West Central Texas next week...between an upper low over the
Great Basin and a low pressure system over the eastern Gulf of
Mexico. Periodic disturbances rounding the crest of the ridge will
generate scattered showers and thunderstorms across the southern
and central Plains...with any convection looking to remain well
north of the forecast area. Otherwise, high temperatures each
afternoon will approach or exceed 100 degrees. The hottest days of
the week look to be on Wednesday and Thursday...when 850 MB
temperatures rise to 31-32 C across the western half of the area.
This translates to surface temperatures in the 100-105 range.
Needless to say, the heat is on with not much rain in sight.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 72 100 72 98 / 5 5 0 0
San Angelo 73 103 73 101 / 5 5 0 0
Junction 71 100 72 100 / 20 0 0 0
Brownwood 72 98 71 96 / 5 0 0 0
Sweetwater 72 103 73 99 / 5 5 0 0
Ozona 70 102 72 100 / 5 5 0 0
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
...Update to aviation forecast discussion...
.Discussion...(This evening through next Saturday)
Issued at 240 PM CDT Sat May 26 2018
Unseasonably warm temperatures will be the story for the
remainder of the holiday weekend, with the possibility of storms
this afternoon and again midweek.
Northeast Kansas was baking under a late May sun this afternoon
with highs toping out in the 90s to even near 100 along the KS/NE
border where a drier airmass promoted more efficient warming. Heat
indicies were about the same throughout the region with dewpoints
10+ degrees higher further south. A band of cumulus clouds has
developed across Brown and Nemaha counties in the last hour or so
along the gradient between these airmasses where weak surface
convergence was also noted. All 12Z HREF members and daytime runs
of the HRRR has indicated that convective initiation will take
place around 20-21Z in this region. With 2000 J/kg of MLCAPE but
weak vertical wind shear, robust but short-lived cell clusters are
anticipated along and east of a line from Marysville to Topeka
this afternoon and evening, ending by 01-03Z as they propagate
S/SW on the collective outflow boundary. With ample mixing today,
DCAPE values of 1500-1800 J/kg will promote efficient downward
momentum transport and downburst winds with any convective cell.
Thus, cannot rule out a severe wind gust with any thunderstorm
this afternoon. The threat for small hail will also exist given
the degree of instability.
High clouds spilling over the top of the approaching H300 ridge
are progged to move into NE Kansas this evening and tonight,
though all synoptic and short-range solutions are failing to
resolve these clouds. Thus have leveraged satellite imagery tends
to advect the cirrostratus shield in overnight. These clouds
linger throughout much of the day tomorrow and call into question
how high temperatures will climb in the afternoon. For now have
kept the going forecast for near record to record highs, but there
is some concern that high clouds may temper these readings by 2-4
degrees.
The upper level ridge pushes east by Sunday night with SW flow
for Monday and Tuesday. The cutoff low over the SW U.S. migrates
northeastward for Monday into Tuesday, dragging a frontal boundary
slowly eastward over the High Plains and Mid-Missouri River
valley. This will serve as the focus for shower and thunderstorm
development midweek, though confidence in timing and placement of
these storms is on the low side. These storms may temper highs
somewhat, but looks for continued above average temperatures
throughout the seven day forecast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 619 PM CDT Sat May 26 2018
VFR prevails at terminals. Despite the short term models showing
convection forming near terminals, current radar and satellite
trends suggest there is not enough focused lift or boundary to
warrant a mention for VCTS through 02Z.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Skow
LONG TERM...Skow
AVIATION...Prieto