Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/29/18
Area Forecast Discussion
National Weather Service Wakefield VA
814 PM EDT Mon May 28 2018
A weak frontal boundary will linger from central Virginia to
the Eastern Shore tonight into Tuesday. The remnant low of
Alberto is expected to track west of the mountains through mid
week as high pressure remains anchored over the western
Atlantic. The moisture ahead of this low will result in
unsettled conditions over the area.
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of 800 PM EDT Monday...
Latest wx analysis features a quasi-stationary frontal
boundary draped across the northern third of the area (Melfa to
RIC to CHO). Per NHC...center of TS Alberto made landfall near
Laguna Beach on the FL Panhandle, with associated moisture is
streaming north along the east coast due to a combination of
Alberto and high pressure over the wrn Atlantic. Scattered
showers and a few tstms have developed mainly along the boundary
this aftn along and north of I-64, with any showers/tstms
capable of producing very heavy rain, as evidenced by 1.42" at
AKQ in less than an hour earlier this aftn. Localized flooding
remains possible this evening, even as activity continues to
diminish with loss of heating.
Meanwhile to the south, an area of rain is tracking across the
eastern Tidewater and NE NC associated with mid-level WAA and
shortwave energy. This area of rain and perhaps a few embedded
tstms will move into SE VA/NE NC through the mid to late evening
hours, with additional sct showers expected over central and
eastern VA into the early overnight hours. While locally heavy
rainfall remains primary threat, have updated to go no higher
than slight chc thunder given instability parameters. Will also
likely see areas of fog develop over the northern half of the
area tonight, with BUFR profiles agreeing with HRRR assessment
that best chance will remain over NW corner of the CWA where
heavy rainfall occurred, though dense fog is less likely given
persistent overcast/mostly cloudy conditions through the night.
Warm and humid/muggy tonight with lows in the mid 60s to low
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
As of 400 PM EDT Monday...
Given Alberto`s remnant low track and the high offshore, models
continue to show more of the deeper moisture bands moving N and
rotating across the Mid Atlantic region through mid week with
the heaviest rainfall across the srn half of the local area.
1.5-2.5" QPF are possible for much of the area (less for the MD
Ern Shore), with localized amounts up to 2.5-3.5" through
Thursday. The boundary will linger over the region Tuesday, then
gradually lift nwd Wednesday, and then N of the area by
Thursday. Timing chcs of rain is difficult, so mainly high chc
to likely PoPs through the period, but expect showers and
embedded tstms to become increasingly diurnally driven through
Wednesday/Thursday. The main concern will be locally heavy
rainfall and flooding, but confidence is not high enough for a
flood watch. Highs both mid 70s/low 80s Tuesday, upper 70s to
low 80s Wednesday, and low/mid 80s Thursday. Lows generally in
the upper 60s to low 70s.
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 410 PM Monday...
Medium range period characterized by continued unsettled
weather, as the remnants of Alberto lift north and become
absorbed by northern stream upper trough over the Great Lakes.
EPS/GEFS in reasonably good agreement that this trough then
dives south/southeast across the Mid-Atlantic over the weekend,
bringing another period scattered to numerous showers and
T-storms...mainly diurnally-driven...to the local area into
early next week. The associated surface front drops across the
area Saturday, and meandering across the region into early next
week. Have held rain chances in the high-end chance to likely
range by day, with chance pops lingering into the overnight and
early morning. Conditions remain warm and muggy through the
period. Highs in the 80s, with early morning lows in the mid 60s
to low 70s.
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
As of 730 PM EDT Monday...
A backdoor front continues to reside over the eastern portions
of the CWA and widespread tropical moisture continues to move
north covering much of the region. TAF sites are bouncing
between VFR and IFR conditions depending on the intensity of
rain or showers moving through. Overall, am expecting
deterioration in conditions through the night as IFR ceilings
and visibilities settle in. Winds are mostly light especially
over the Piedmont and Central Va so some areas of dense fog
possible overnight. Isolated convection may produce some thunder
especially over NE NC and SE Va. Rain/drizzle/fog expected
through Tue morning with generally IFR conditions slowly
improving to MVFR/VFR during the afternoon. Showers and
thunderstorms again possible during the afternoon/evening.
Outlook: Scattered showers/tstms are possible over the next
several days with an influx of tropical moisture from the deep
south, along with the potential for late night/early morning
As of 430 PM EDT Monday...
No headlines in the short term tonight thru Wed. Late this aftn,
backdoor front was still laying near a Cape Charles westward to
York River line. ENE winds 5-15 kt were occurring N of this
boundary, while SSW winds 5-15 kt continue S of the line. This
boundary will lift north of the area tonight, with winds
becoming SE or S. Another backdoor front will drop into/thru the
area Tue night and Wed, with wind speeds remaining mainly 15 kt
or less. However, seas over the far nrn ocean waters may reach
5 ft by Wed aftn. Sctd tstms could be accompanied by gusty winds
As of 345 AM EDT Monday...
* RIC monthly rainfall total through 5/27 is 10.27" which now
ranks as the wettest May on record. (breaking the old record
of 9.79" in 2016). (Precipitation records date back to 1880).
* SBY monthly rainfall total through 5/27 is 9.66". Through the
27th, this already ranks as the 2nd wettest May on record
(wettest is 10.38" in 1948). (Precipitation records date back
Area Forecast Discussion
National Weather Service Caribou ME
1049 PM EDT Mon May 28 2018
A cold front will approach this evening and cross the area
overnight. High pressure will build in from the northwest on
Tuesday and crest over the area Wednesday. High pressure will
move south of the region Wednesday night into Thursday.
.NEAR TERM /THROUGH TUESDAY/...
1030 PM Update...
The threat for convection appears to be waning using the latest
RAP/HRRR showing the stronger cells weakening as they move into
Maine. The 00Z CAR RAOB showed a stable layer of about 3k ft
which would aid in suppressing any convection activity. The RAP
soundings do show some elevated CAPE of 500 joules around
midnight but this looks overdone compared to the latest Near
Storm Environment showing at best 200 joules in Quebec. There is
still a threat of some heavy rainfall w/the showers expected to
move across the region overnight as PWATs are around 1.3 inches.
There is moisture up through 700 mbs but this seems to be drying
up as the 00Z UA analysis showed 700 mb moisture pushing to the
east. There is still some decent shear noted at both 0-3km and
0-6km of 30 kts. So, some wind gusts to 25+ mph are possible in
the line of showers later tonight as the front apchs.
Adjustments were made to the POPs to take into account the
latest radar trends showing the best activity across the
northern 1/2 of Maine. Kept the threat for fog across the coast
and waters into early Tuesday morning.
Moisture ahead of a cold front will continue to bring a mostly
cloudy sky this evening. Some showers ahead of the front will be
scattered across the north and west this evening. Most of the
showers are expected to be light and spotty. A cool layer
between 3K and 5K feet will prevent any deep convection ahead of
the front tonight. The cold front will push across the area
during the predawn hours on Tuesday followed by clearing Tuesday
morning. Tuesday will then feature bright sunshine with a gusty
northwest wind as high pressure pushes down from the northwest.
The gradient will weaken Tuesday afternoon allowing the wind to
diminish late in the afternoon.
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
High pressure will dominate the middle of the week with clr skies
and near calm winds expected to build in Tue night as winds
decouple. Hv undercut guidance slightly tho may not be cold enuf for
mins Wed mrng ovr deeper vly locations. At this time may see patchy
frost in far wrn reaches of the St. John Vly bfr daybreak given
current fcst lows.
Only significance of not drg the rmndr of the short term wl be the
warm temps due in on Thur. H9 temps soar to +22C and abv north of
the Katahdin region per GFS with latest NAM about 1-2 degrees cooler
aloft with CMC the compromise. As a result hv lowered high temps by
a degree or two fm prior fcst with max temps drg the day common in
the m80s acrs nrn and wrn areas under sw flow aloft. With onshore
flow drg the day expected to keep coastal areas cool, relatively
speaking, highs wl be hard-pressed to climb into the l/m 70s.
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Sfc high wl be building south and out of the area. Upr lvl ridge wl
be breaking down Fri morning as wv assoc with Alberto gets captured
by trof mvg acrs upr Midwest. CWA shud starting feeling the impacts
fm system Fri ngt. Showers shud dvlp Fri mrng in wm sector with
airmass destabilizing in the aftn. PW values appch 2 inches Fri aftn
and evng, thus hv added in hvy rain with any storms that can dvlp
ahd of front.
Fropa looks to occur sometime on Sat with GFS mvg it offshore by
18z with CMC slower and EC the compromise. As a result hv included
slgt chc thunder for srn zones Sat aftn. With area being in the
wmsector Fri night expect to see patchy fog area-wide.
In wake of fropa expect hipres to follow into early next week.
Latest Euro building 576 ridge acrs the region while rmng med range
guidance is flatter with flow. Hv sided with Superblend to retain
isold showers thru the end of the pd. Following fropa expect that
temps wl return to near normal values, and possibly slightly blo,
thru early next week.
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
NEAR TERM: Low clouds will result in IFR conditions Downeast
this evening followed by an improvement to VFR late tonight. VFR
conditions are expected across the north tonight and throughout
the area on Tuesday.
SHORT TERM: VFR expected through the end of the week with
possible tstorms bringing MVFR restrictions on Fri afternoon.
Locally hvy rainfall is possible with any storm.
NEAR TERM: Winds and seas are expected to be below SCA tonight
and Tuesday. Fog may limit visibilities over the water tonight.
The visibility will be good following the cold front early
SHORT TERM: Seas and winds remain below SCA levels through most
of the week. Visibilities may be reduced in fog Fri night
through Sat morning before a cold front crosses the waters. May
see winds increase to marginal SCA thresholds late Sat night.
Area Forecast Discussion
National Weather Service Cleveland OH
808 PM EDT Mon May 28 2018
Weak high pressure will remain over the region tonight. Stronger
high pressure will build southeast across the Great Lakes
tonight and Tuesday. The remnants of Alberto will move north
into the central Great Lakes Wednesday, passing just west of the
.NEAR TERM /THROUGH TUESDAY NIGHT/...
Isolated showers and thunderstorms developed between 3-6PM from
Marion east to Stark County and drifted southwest with time.
Although hard to see beneath the cirrus, the cu field has
thinned and showers have diminished. Some weak surface based
convergence remains across NE Ohio but doubt we will see any
additional development. Will update to remove the remaining
isolated thunderstorm mention in the next hour or so. With high
dewpoints remaining across inland NE Ohio will also add a
mention of patchy fog from from Millersburg to Canton to
Record heat will continue across the area this afternoon,
although dew points have mixed down into the low 60s to upper
50s across parts of the area. Main focus for the rest of this
afternoon is potential isolated TSRA roughly along and south of
a Marion to Youngstown line. HRRR runs throughout the day have
been consistent with developing the isolated convection by 20Z
across the area, and latest satellite and radar trends show a
few cells trying to develop near Canton. Will hold with the
previous iso TSRA mention in the grids through the early
High clouds will remain across the area tonight with high
pressure over the area. A warm and humid night is expected, with
lows only dropping into the mid/upper 60s across the area, and
dew points in the low/mid 60s. Some patchy fog cannot be ruled
out with light winds, but should mainly be in low lying areas
across the southeast part of the forecast area, where dew points
have remained in the mid/upper 60s this afternoon at peak
mixing. Not anticipating dense fog at this point with the higher
clouds streaming north from subtropical storm Alberto, but where
convection develops tonight, will need to watch for early fog
Tuesday should be a fairly similar day to Monday, with a bit
more high clouds expected, as well as some lower/mid level
moisture streaming into the region as Alberto makes its way
inland toward the Tennessee valley. This should allow for a bit
more diurnal cu on Tuesday and dew points remaining a degree or
two higher through the day. Will continue to leave slight chance
pops in the forecast Tuesday with similar instability to today.
Highs are a touch cooler on Tuesday, but most of the area should
still reach the upper 80s to low 90s. The remnants of Alberto
will continue northward into the southern Great Lakes Tuesday
night, passing west of the region. Moisture will increase
through the night across the area, but models have backed off a
bit timing-wise with precip. Looks like most of the area may
remain dry through the night, with just some stray shower
activity before Wednesday morning.
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Wednesday begins with low pressure moving north out of over
southern Indiana, the remnants of Alberto, with deep, tropical
moisture across the Ohio Valley and lower Great Lakes. Do now
anticipate a solid shield of rain however diurnal forcing will
provide enhancement to the convection with a likely flare up
during the day. Best chance will be west closer to the path of
the low as it moves north through Indiana, however there will
still be a chance of convection across northern PA as well. Will
have categorical pops west, likely for the balance of northern
Ohio and chance for nwrn PA. Will start out Wednesday night with
likely pops everywhere with the low centered in sern lower MI
however will drop to chance pops after midnight as focus of
forcing shifts north with the low. Thursday the tropical low
continues northeast however another low will be approaching from
the west across the western lakes. Will boost pops back to
likely ahead of this approaching system with leftover tropical
moisture still across the area. Friday the system moves through.
Will have likely pops east and chance west. temperatures mostly
lower 80s Wednesday and Thursday. Highs upper 70s to lower 80s
.LONG TERM /FRIDAY THROUGH MONDAY/...
Although track and timing between the models differ, both models
move large upper level trough east of the area and off the East
coast Friday night. Will go with chance pops for the area Friday
night to cover the lingering showers. AFter that both models have
high pressure pushing south across the Lower Great Lakes Saturday
for a dry day. After that models diverge. Both models form
upper level low from trough on east coast. GFS has the low
sliding south along the East Coast with a secondary low tracking
into the Ohio Valley. ECMWF on the other hand retrogrades low
over the area on Monday. For now will superblend temps and go
with low chance pops on Monday.
.AVIATION /00Z Tuesday THROUGH Saturday/...
High pressure will remain over the area with winds dropping off
to near calm overnight. Although cirrus will continue to move
overhead, dewpoints remain high in the mid to upper 60s across
inland NE Ohio and could see patchy fog develop after 08Z at
CAK/YNG/MFD. Generally expecting patches of MVFR fog but could
drop to IFR prior to sunrise so included a 2 hour tempo group.
Otherwise fog expected to burn off quickly on Tuesday morning
with easterly winds inland and NE winds near the lakeshore.
OUTLOOK...NON-VFR possible Wednesday through Thursday.
Light and variable flow will continue across Lake Erie overnight.
Tuesday, a weak cold front will drop south across the lake as high
pressure moves east through Quebec. Winds behind the front will turn
northeast on the lake increasing to 15 to 20 knots west by late
afternoon/early evening. Main concern will be for the need for a
small craft advisory but for now believe for the most part waves
will remain below criteria. With a northeast flow the lake level is
also of concern. At this time levels on the west end are expected
to get above 5 feet above low water datum Tuesday afternoon/evening
but should not get to warning levels of 6 feet. By Wednesday morning
winds will veer to the southeast at 15 to 20 knots in response to
low pressure moving north through Indiana, the remnants of Alberto.
A small craft advisory should not be needed given the southerly wind
direction. Flow will turn south Wednesday night and then southwest
Thursday as the remnants of Alberto continue northeast and another
low moves into the central lakes from the west. The low will
continue east of the area by friday afternoon dragging a cold front
across the lake. Expecting winds to turn northerly behind the front
Friday evening/night around 15 knots.
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1045 PM EDT Mon May 28 2018
Deep tropical moisture will persist over the area through Wednesday
as the remnants of Alberto move northward from Georgia to Kentucky
and eventually to the Great Lakes. A moist airmass will persist into
Friday before southerly flow shifts more to the west. Warm yet a
little drier air will mix in from the west over the weekend.
.NEAR TERM /THROUGH TUESDAY/...
As of 1030 PM EDT...The main rain band from Albert has finally
pushed into our GA counties, producing torrential downpours,
cg-lightning and a few wind gusts. It has been on a general
weakening trend, as we have lost daytime heating and shear is
marginal. So while not entirely zero yet, the severe threat looks
very low. The latest HRRR takes this band north over the next couple
hours and produces some decent simulated reflectivity along the
southern escarpment for the post-midnight hours. This may pose some
problems with mudslides and flooding overnight for areas that
received heavy rain over the last few days. Otherwise, the rest of
the forecast area is looking like it may see a lull in flood threat
overnight. However, additional heavy rain bands will develop over
the area Tuesday. So I will leave the Flash Flood Watch as is.
With scattered to overcast skies, showers and isolated
thunderstorms should persist through the overnight, with higher
rainfall amounts most likely over the upslope areas tonight and into
tomorrow morning. High temperatures will remain slightly below
normal while low temps will remain well above normal.
On Tuesday, the NAM and GFS both show about 1500 J/kg across the
I-85 corridor by late aftn, as some breaks in the low overcast is
expected, allowing some insolation. This will be combined with 0-6
km shear of 20-30 kts and SRH of around 200 m2/s2. The CAMs do show
some discrete cells that may track NE within bands of enhanced
emanating from TC or (post-TC) Alberto as it tracks into central TN.
The SPC Day 2 Outlook has a marginal risk for severe weather across
the entire area, with isolated brief/weak tornadoes being the
biggest threat. Highs will be near normal east and below normal west
under the continued moist tropical air mass.
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 110 PM Monday: A very moist and complicated pattern continues
thru the short term. The remnants of TC Alberto will continue
pulling north as it/s picked up by a developing mid/lat trof.
Meanwhile...a general weakness in the sub/trop ridge will persist
over the SE CONUS which will maintain moist GOM/Atl flow trained on
the FA. Deep layered moisture will remain elevated with PWATs
persisting abv 1.5 inches. Soundings show continued low-end
conditional instability each afternoon within little shear...so
general short-lived tstms are possible just about anywhere each
afternoon. Otherwise...very little forcing will be had...so the
better precip/rate enhancement will be associated with mech lift
where another 1-2 inches of rainfall is possible thru early Thu.
This amt of rain could lead to continued and/or additional flooding
concerns across the srn and ern BR...thus the FFA will be extended
in time thru 12z Thu across the mtn zones. Max temps will remain
arnd normal Wed and a little abv normal Thu. Mins will persist abt
10 degrees abv normal each morning.
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 155 PM Monday...A broad ulvl trof will remain across the east
coast to begin the period. Small scale pockets of h5 energy will
traverse the FA...however overall ulvl forcing will remain weak
until a more defined trof dives south out of the glakes region on
Sun. The good news is moisture transport vectors within the llvls will
begin to veer w/ly early Fri which will decrease the chances for
precip over the non/mtns and limit any new hydro threats. The area
will remain in a highly moist environ Fri however...which will make
for a muggy day as high temps reach a cat or so abv normal.
There is some uncertainty with the degree of airmass mixing
associated with a frontal system Sat which looks to stall out across
or just south of the FA thru the weekend. The GFS is drier and
wetter with the pattern Sat than the ECMWF...however both models do
show a diurnal precip trend which would mean isol to sct convec each
afternoon. A few storms could become quite strong or severe with
hail and gusty winds being the biggest threat mainly across the NC
mtns...while the non/mtns will be a little more stable with lowering
td/s in downsloping w/ly H9-H8 flow. The aforementioned ulvl trof
will reach the area Sun afternoon or evening and this could
instigate more widespread showers and tstms late Sun into Mon. Max
temps over the weekend will remain abv normal by a cat or so...while
mins remain well abv normal by abt 10 degrees.
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Instability has increased across the Upstate,
but convection remains shallow, with little lightning. Will opt for
prevailing shra and vcts at the three Upstate sites. For KCLT and
other NC sites, mainly going with SHRA this evening thru the
overnight. Guidance in good agreement on continued rain bands
pivoting northward thru the area, producing low cigs and occasional
low vis in downpours. Winds are generally ENE, but will gradually
veer to ESE, then SE overnight thru Tuesday morning. Wind speeds are
generally 5-12 kt. Another lull in shower coverage is expected in
the morning, then daytime heating should produce another round of
numerous showers and tstms in the aftn. Cig will improve gradually
from IFR to MVFR with some VFR breaks by mid-aftn.
Outlook: Tropical moisture will linger through at least thru
Wednesday. So expect continued rounds of numerous to widespread
showers and embedded thunderstorms with low cigs and occasional low
vis across the region. Slightly drier air is expected to start
working into the area on Thursday, but diurnal convection is still
02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 90% High 80% Med 66% High 82%
KGSP Med 68% Low 55% Med 60% High 90%
KAVL High 86% High 92% High 89% High 100%
KHKY High 92% Med 77% High 88% Med 72%
KGMU Med 66% Low 51% Low 58% High 94%
KAND Med 76% Med 60% Med 63% High 94%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
Heavy rainfall over the past two weeks across much of the forecast
area, particularly the mountains, has set the stage for serious
flooding and landslide issues to possibly develop with any
additional tropical rainfall through mid-week. Numerical model
profiles exhibiting precipitable water values over two inches and
deep warm cloud layers in excess of 12 kft will make for highly
efficient heavy rainfall processes and further increase the threat
of flash flooding and river flooding. The latest 3/6 hour FFG
guidance values are generally running 2.5 to 3.5 inches and these
will be quite achievable in the expected waves of heavy tropical
rain showers...especially across the higher terrain. Hydro problems
will likely continue through Tuesday and possibly into late
Wednesday as heavy tropical rainfall continues in waves.
GA...Flash Flood Watch through Thursday morning for GAZ010.
Flash Flood Watch through Wednesday morning for GAZ017-018-026-
NC...Flash Flood Watch through Thursday morning for NCZ033-048>053-
Flash Flood Watch through Wednesday morning for NCZ035>037-056-
SC...Flash Flood Watch through Thursday morning for SCZ001>003.
Flash Flood Watch through Wednesday morning for SCZ004>014-019.
Area Forecast Discussion
National Weather Service Jackson MS
1013 PM CDT Mon May 28 2018
Updated for evening discussion.
Convective precipitation associated with the outskirts of
"Alberto" has diminished with loss of heating and have reduced
rain chances for the overnight. The latest HRRR guidance is
bearish with any additional shower activity, but will maintain
some continuity with previous forecast and also to match up with
neighboring WFOs. The remainder of the forecast elements are
generally on track for the near term and no significant
adjustments were necessary. /CW/EC/
Prior discussion below:
Tonight and Tomorrow: The threat of any impacts from Alberto in
our region remain low. Rainfalls totals should`t eclipse 1.0" for
most locations with higher chances of precipitation. Lows tonight
should fall to near 70 degrees areawide with highs on tomorrow
ranging from the low 90`s along and west of the MS River to the
mid 80s in eastern MS where cloud cover from Alberto will obstruct
the sun. /jpm3/
Tuesday night through Sunday: Come Tuesday night Alberto is expected
to be moving north from the Tennessee Valley toward the Great Lakes
region. In its wake, mid to upper level troughing will linger over
our CWA through Wednesday morning but this trough axis will shift
east through the day as mid level ridging begins building into our
region from the southwest. A moist airmass with a PWAT in excess of
1.7in will also remain over our region Wednesday and support mainly
diurnal convection but greatest coverage will continue in the east
with the least coverage in the west. This will result in warmest
afternoon temperatures in the west as well. This warmer and drier
trend look to continue into Saturday As the mid level ridge
strengthens over the region. However, there remains differences in
the models with the strength of the ridge and a couple disturbances
that are expected to top it.
The first disturbance is expected Thursday but model consensus
suggest associated rain chances will remain to our north. With
little convection expected in our CWA most sites look to top out
in the lower 90s. Normal highs run 85-88F. Another disturbance
looks to drop around the mid level ridge Friday and model
consensus suggests associated convection may infringe on our
eastern most zones. Yet another disturbance is expected Saturday
again with rain chances being carried in our east. This will allow
for a warming trend with dry weather for at least the western two
thirds of our CWA Thursday through Saturday. With temperatures
topping out in the mid 90s combined with high humidity, heat index
values look to top out around 105F Friday and Saturday
afternoons. Wl continue this mention in the HWO. Although there
remain differences in the models for Sunday, consensus is that
upper level troughing and a cold front will drop over our region
leading to greater rain chances and cooler temperatures. /22/
00Z TAF discussion:
Aviation hazards will be largely influenced by Subtropical Storm
Alberto. Look for gusty NE/N wind and showers to diminish early
this evening with increasing shower chances late tonight in the
GTR to perhaps MEI area when the center passes at it`s closest
point to eastern MS. There will be an increase in mostly MVFR
ceilings along/east of the I-55 corridor early Tuesday morning
persisting until around noon before mixing upward to VFR category.
GTR looks to experience the worst of impacts associated with STS
Albert Tuesday with RA/VCTS likely going into the afternoon. At
other sites, VCSH/VCTS could be a concern late morning and
.PRELIMINARY POINT TEMPS/POPS...
Jackson 69 87 71 92 / 15 31 21 30
Meridian 69 86 70 89 / 30 52 38 43
Vicksburg 69 89 71 93 / 7 19 7 19
Hattiesburg 69 89 71 91 / 22 26 34 48
Natchez 69 89 72 91 / 7 19 6 17
Greenville 70 87 72 93 / 7 29 16 25
Greenwood 69 85 70 92 / 14 46 27 33
Area Forecast Discussion
National Weather Service Mount Holly NJ
827 PM EDT Mon May 28 2018
Weak high pressure will remain across the area tonight through
Tuesday night. The high will move away Wednesday as low pressure,
the remnants of Alberto, move across the Ohio Valley. A warm front
associated with this will approach from the south. Rather unsettled
conditions will remain for the end of the week and into the weekend
as low pressure aloft affects the region.
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Low clouds are redeveloping across the area as the sun sets
this evening. In addition, the flow is expected to become more
westerly overnight, albeit light. Given the lack of continued
onshore flow, considerable low clouds (due to the inversion
mentioned previously), and fog parameters no more robust
compared to last night, confidence in widespread dense fog is
low. Therefore, kept patchy fog in the forecast, which may be
With the loss of daytime heating, absence of a pronounced surface
boundary, and generally weak large scale descent aloft, kept the
forecast dry for tonight.
Hourly temperatures were adjusted based on a blend of short term
guidance (weighted toward the RAP), and the previous forest for
continuity. This resulted in little, if any change, to the low
temperature forecast, with values several degrees above seasonal
norms, due to the cloud cover.
Showers have developed in portions of Delmarva early this afternoon,
on the northern fringe of larger-scale lift associated with a quasi-
zonal, elongated vorticity lobe positioned from the Ohio Valley to
the central Mid-Atlantic coast. Hi-res simulations have not
accounted for this development well (generally too far to the south
with coverage being too sparse), so included some slight-chance PoPs
the rest of the afternoon generally from Kent County (MD and DE)
With a surface ridge in place to the north of a deformation axis
located in far southern portions of the Mid-Atlantic this afternoon,
the low-level inversion has held strong across the area today, with
a cloud deck stubborn to erode across the area this afternoon. Light
surface flow and a subtle onshore component near the coast have
contributed to the mostly overcast day. Models suggest there may be
a small time window in which some breaks in the clouds occur before
sunset, but the general model bias has been too optimistic today.
Therefore, the confidence on such occurrence and its duration is
The forecast tonight is a challenge owing to the potential
implications of the current low-cloud deck on the development of fog
across the area. Should the clouds remain in place, the development
of more widespread fog would be less likely, even with slowly
increasing dew points and light surface winds. Nevertheless, the
pattern is certainly favorable for at least patchy fog, especially
in rural/valley locations and near the coast, where a subtle onshore
fetch will remain and the cooler ocean waters will contribute to
rapid saturation after dark.
With these conditions in mind, basically have mention of patchy fog
everywhere after 03Z (areas of fog along the coast and offshore).
Regarding PoPs, confidence is lacking given the proximity of lift to
the southern CWA and at least some indications from the HRRR that
showers may attempt to lift northeastward into far southern New
Jersey early this evening. For now, though, have kept PoPs
unmentionable for the tonight period pending improved hi-res model
Temperatures will not drop much tonight owing to the increased cloud
cover/fog and slowly increasing dew points. Generally have lows in
the 60s across the CWA, with strong weighting given to consensus raw-
model output given its somewhat better performance recently with
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
Very challenging forecast tomorrow, with subtle surface (and upper-
level) meteorological phenomena in play and little agreement among
raw-model and statistical output.
The large-scale pattern will feature midlevel ridging becoming a
little bit stronger across the Northeast in advance of the remnants
of Alberto to the southwest. Midlevel perturbations will continue to
progress eastward in proximity to a deformation axis across the
southern Mid-Atlantic. Warm-sector precipitation will develop to the
south of the deformation axis, which will likely remain south of the
CWA through the day. However, like today, we may see some
development creep into the far southern portions of the area
(generally central/southern Delmarva), so kept some mention of PoPs
here. Meanwhile, a surface high will progress into New England and
adjacent areas during the afternoon, with an apparent (albeit very
weak) surface trough in place across the Appalachians. Terrain
effects in combination with differential heating and subtle
mesoscale convergence associated with the surface trough will likely
be sufficient to initiate some convection during the afternoon to
our north and west. Cannot rule out a storm or two developing in our
CWA during peak heating, especially northwest of the Fall Line. Most
locations will be dry tomorrow, but the environment in place (plus
the subtle nature of potential initiating mechanisms) precludes me
from eliminating PoPs entirely.
With the southern CWA in closer proximity to the deformation axis
and associated large-scale lift, expect cloud cover to be denser and
longer-lived in these areas tomorrow. Meanwhile, the
northern/western CWA may break out into some sun sooner. Thus,
temperatures may actually be warmer to the north and west and cooler
to the south during the afternoon. However, confidence on max temps
is low. A comparison of MOS guidance for KPHL is instructive: 12Z
MAV is 89, 12Z MET is 79, and 12Z ECS is 86. The erosion of the
cloud cover will be critical to the accuracy of the forecast. I did
not stray too far from consensus, as the subtly stronger ridging may
counteract the models` tendencies to erode cloud cover too
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
High pressure will be dropping across the Northeast states and the
Canadian Maritime provinces Tuesday night and Wednesday. This will
mostly keep fair weather across the region along with seasonable
temperatures. There could be some patchy fog Wednesday morning in
rural areas. Lows Tuesday night will be in the low 60s up north and
mid/upper 60 elsewhere. Highs on Wednesday will mostly be in the 70s
with a few 80s near Metro Philadelphia.
Unsettled conditions will prevail through much of the long range as
the remnants of Alberto move well to the west of the area and a
decent batch of moisture is drawn northward with it. Several upper
lows will affect the area into the weekend which will help trigger
almost daily chcs for showers and tstms. Right now Thursday and
Saturday look to be the the days with the higher chcs for showers
and tstms with high chc and low likely pops in the grids. The other
days have mostly low chc pops. Wet ground across the area could lead
to some hydro concerns later this week if organized convection
develops. Low confid in this happening attm.
Temperatures for most of the long term will average normal or below
with frequent clouds and sct showers predominating. One exception
will be Friday when partly sunny skies may allow for highs to reach
the mid 80s in most areas. Conditions will be rather humid through
the period, especially the weekend with dew points in the 60s to low
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Tonight...CIGs should deteriorate to IFR 02Z-06Z, with the
potential for LIFR at some sites after 06Z. There is also the
potential for fog, though confidence in fog
development/location/timing is fairly low. Winds should be
light/variable. Overall confidence is low.
Tuesday...Improvement to MVFR during the morning and VFR by
afternoon is expected, though confidence with timing is low.
Winds remain southerly or southwesterly around or below 10 kts.
There is a slight chance of storms during the afternoon (especially
north/west of PHL), but coverage looks sparse should these
develop...so no inclusion in TAFs at this point. Overall confidence
Tuesday night and Wednesday...Mostly VFR. Fog psbl early Wed.
Wed night thru Saturday...Mostly VFR. Patchy rural fog psbl
during the pre-dawn and sct showers/tstms during the afternoon
or early evening hours.
Sub-advisory winds/seas are expected through Tuesday. Conditions may
become favorable for fog tonight, but dense fog is not expected at
this time, as the dew points - Sea Surface Temperatures differential
based on buoy observations is not favorable. The pattern should
be more conducive to dense fog Tuesday Night.
Sub-SCA conditions expected. Scattered showers and tstms Wed
night thru Saturday with locally higher winds and seas.
Through this evening...The risk for the development of dangerous rip
currents is moderate for the NJ beaches and low for the DE beaches.
Tuesday...A moderate risk for the development of dangerous rip
currents is forecast for the NJ beaches due to a combination of an
increasingly onshore component of wind throughout the day up to
around 15 mph, multiple swell groups of similar magnitudes (several
sets from the south-southeast to the east-northeast with 7-9 second
periods) which should lead to shorter periods of higher waves,
and a full moon (larger variations in tides, accentuating water
For the DE beaches, a low risk for the development of dangerous rip
currents is forecast, due to the wind being both parallel to the coast
Remember, a low risk of rip currents does not mean no risk!
Life threatening rip currents often still occur near jetties,
reefs, and piers. The vast majority of rip current victims swam
at unguarded beaches. ALWAYS SWIM IN THE PRESENCE OF A
The Sandy Hook NOS tide gauge (SDHN4) remains out of service.
CORMS is addressing the problem. There is currently no estimated
time for a return to service.
Area Forecast Discussion...UPDATED
National Weather Service Portland OR
905 PM PDT Mon May 28 2018
Updated Short term and Aviation sections
.SYNOPSIS...A series upper level troughs will maintain onshore winds,
and a cooler marine influence tonight through Thursday with
night and morning clouds and a mix of sun and clouds in the
afternoons. Brief ridging will provide a warmer day on Friday before
another upper level trough arrives for next weekend.
.SHORT TERM...Today through Thursday...Evening Update: Am finding it
very difficult this evening to identify what`s left of the cold
front and precisely where it might be located. There is not much
conclusive evidence on satellite or surface obs. Decided to pare
down cloud cover for tonight and tomorrow given the lack of
continuity in the cloud field over the waters. For sky cover tonight
and early tomorrow, have leaned fairly heavily on a combination of
the HRRR and Canadian regional model as they are showing the closest
representation of reality at this time. Even so, expect inland cloud
cover will be highly variable tonight with little confidence for any
given location. Updated text and grids have been sent. /JBonk
Previous discussion follows: A weak cold front will fall a part as
it moves across extreme SW Washington and NW Oregon this afternoon
and evening. This front will most likely just impact the sky cover
where there will be variable cloudiness across the region. Areas
south of Salem will be less impacted or not impacted at all by this
The marine layer will deepen tonight as an upper level trough
approaches. This combined with light onshore flow will allow any
marine clouds that develop along the coast tonight to move through
the coastal valleys into the Willamette Valley and parts of the
Cascade foothills early Tuesday morning. There will be partial
clearing Tuesday afternoon, but the afternoon temperatures should cap
just below 70 degrees inland and the low 60s for the coast.
There will be little change in the weather Tuesday night and
Wednesday as a short wave trough reinforces the broader upper trough
over the area. There may be enough lift to squeeze out brief light
rain or drizzle along the north coast and the Willapa Hills late
Tuesday night into Wednesday, but do not expect much if any rain
Another upper trough arrives Wednesday night and Thursday maintaining
nocturnal coastal clouds, and inland afternoon clearing with
Temperatures peaking in the 60s. There will be slightly more
available moisture with this trough, and there is a slight chance for
showers along the coast and coastal mountains Thursday morning, and
over the Cascades Thursday afternoon. ~TJ
.LONG TERM...Thursday night through Monday... A shortwave through
finally pushes up and over the Cascades Thur night. Fri a shortwave
ridge makes a brief stop, only to be pushed out Fri night, as the
next system looks to approach the area, which looks to linger in the
area though the weekend. The GFS and Euro disagree on if
precipitation will happen within this time frame. The best chance
for precipitation according to the GFS is from Sat evening through
Mon as the trough makes its way into the area. However, The Euro
currently has little precipitation, as it is pushing the system much
further north towards Seattle within the same time frame. As a
result I am keeping PoPs above Climatology,as we have a slight dry
bias for the area. Especially, as the models continue to change and
develop as to how this next system approaches. /42
AVIATION...VFR conditions across most of the region this
evening, with some low marine stratus developing along the
central Oregon coast. With an upper trough moving into the
region, expect localized low VFR to higher MVFR ceilings to
settle into more widespread MVFR conditions late overnight/early
Tuesday. Gusty north winds will continue both at the coast and
through the Willamette Valley into the evening, briefly easing
overnight/early Tuesday, but again increasing during the
afternoon hours on Tuesday. Expect cloud deck to gradually lift
and begin to scatter late Tuesday afternoon inland, but clouds
may remain banked up along the Cascades and foothills much the
KPDX AND APPROACHES...VFR this evening under mostly clear skies,
but likely will see low VFR to MVFR cigs develop late tonight
after 12z and lingering through early Tuesday morning. Expect
cigs to lift slowly with daytime heating and scatter around 22z
Tuesday. North to northwest surface winds ease overnight but will
again be gusty Tuesday afternoon to 15 kt. Cullen
.MARINE...No Changes Made. A ridge of high pressure offshore will
continue through much of the week with lower pressure inland over
the Pacific NW and over Northern California. This will create a
tendency for winds to be from the N or NW. Winds are expected to
reach Small Craft Advisory thresholds in the afternoons and evenings
through Tuesday evening, then be below Small Craft Advisory
thresholds until possibly the weekend.
Seas were around 7 ft this afternoon, and will be in the 7-9
foot range tonight through Tuesday from the increasing north
winds. Seas will then ease back down to 6-7 ft during the mid
week period as a broad upper trough sags in across the area. Seas
will become choppy during the peak winds in the afternoons and
PZ...Small Craft Advisory for winds until 10 PM PDT Tuesday for
Coastal Waters from Cape Shoalwater WA to Cascade Head OR
out 60 NM.
Small Craft Advisory for winds until 2 AM PDT Wednesday for
Coastal Waters from Cascade Head OR to Florence OR out 60
Small Craft Advisory for Rough Columbia River Bar from 3 AM to
8 AM PDT Tuesday.
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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. This area is
commonly referred to as the CWA or forecast area.
Area Forecast Discussion
National Weather Service Pueblo CO
909 PM MDT Mon May 28 2018
Issued at 909 PM MDT Mon May 28 2018
Updated forecast to expire Red Flag warning.
.SHORT TERM...(This evening through Tuesday)
Issued at 225 PM MDT Mon May 28 2018
An upper level low will continue lifting northeastward tonight acrs
northwest CO and into eastern WY. For the rest of the afternoon,
thunderstorms are developing along and near the eastern mtns, and
generally moving north to northeast. Will have tstms in the
forecast the rest of the afternoon along the ern mtns and I-25
corridor, with best chances for severe storms over portions of
Pueblo and El Paso counties and maybe Crowley. Then for this
evening, the HRRR has very little chance for precip acrs southeast
and south central CO after 00Z, except over northern Teller and
eastern Kiowa counties. The NAM, GFS and RAP are similar to the
HRRR, showing tstm chances mainly over part of El Paso and Teller
counties (mainly northern portions), and maybe parts of Kiowa
county. Will also keep some POPs in the forecast for some of the
Continental Divide this evening, and for areas mainly north of
highway 50 and then along the KS border.
Later tonight the forecast models show a lines of storms working
south into Kiowa county, then moving east in the mid to late morning
hours on Tue.
Tue the upper low is forecast to start tracking more north than
east, into northwest SD and southwest ND, leaving much of southern
CO dry for the day. The exception to this is the isolated precip
showing up in the models over some northern portions of southern CO,
including Teller and El Paso counties in the afternoon, and maybe
.LONG TERM...(Tuesday night through Monday)
Issued at 225 PM MDT Mon May 28 2018
Models continue to be in general agreement through the extended
period with slightly higher forecast confidence. Main concerns
will be thunderstorm potential through Wednesday, and fire weather
concerns on Friday.
Tuesday night through Wednesday...an upper level disturbance is
forecast to lift northeast into the Northern Plains by Tuesday
evening. Models indicating isolated shower and thunderstorm
activity over the Central Mountains through the evening hours
before dissipating overnight. Models progs are also indicating the
potential for an isolated thunderstorm across the far Eastern
Plains during the evening hours. Any thunderstorms that do develop
out east will quickly move east into Western Kansas during the
evening, with dry conditions expected overnight.
On Wednesday, expect a quick moving disturbance out of New Mexico
to lift north across the area as upper level shortwave ridging
moves across the area. Increased southwest flow and modest
instability will lead to shower and thunderstorm development by
mid day over the mountains. As the upper disturbance lifts across
the region, expect continued shower and thunderstorm development
from the Palmer Divide, southeast across the Eastern Plains during
the afternoon and evening hours. The potential exists for a few of
these storms to become strong, and perhaps severe with large hail
and damaging winds being the primary threats. This activity will
shift east across the Plains through the overnight hours, clearing
to the east late Wednesday night.
Thursday through Saturday...expect drier conditions across the
region for the end of the workweek into the weekend. Southwest to
westerly flow will increase, especially on Friday. This will lead
to increased fire weather concerns across the region for Friday
with strong gusty winds and low humidity values due to a quick
moving upper level disturbance. This will need to be monitored. By
Saturday, expect weaker flow across the region with less fire
weather concerns. Temperatures will also be warm with many
locations across the Plains pushing 100 degrees.
Sunday and Monday...better chances for showers and thunderstorms
will once again be possible heading into early next week.
Increased moisture across the Plains and energy across the region
will allow for the thunderstorms to develop. Temperatures will
also be slightly cooler across the region. Mozley
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 225 PM MDT Mon May 28 2018
Gusty south to southwest winds are expected through early this
evening at KALS, otherwise VFR conditions are expected, with lighter
winds on Tue. Gusty eastern winds are expected this afternoon at
KCOS and KPUB, then becoming westerly this evening.
Forecast models show the potential for tstms at KPUB and KCOS
beginning around 22Z and continuing thru about 00Z.