Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/10/20
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1044 PM EDT Wed Sep 9 2020
.SYNOPSIS...
A warm and humid air mass will be over the region tonight with
some showers moving into locations south of the Interstate 90
corridor after midnight. A disturbance moving along a front
south of the region will bring showers and a chance of
thunderstorms in the late morning into the afternoon from the
Capital Region south and east. A cold front will bring
additional isolated to scattered showers and thunderstorms in
the afternoon into the evening, as it sweeps across the region.
A much cooler and drier air mass will settle into the region
Friday into Saturday.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
As of 1030 PM EDT...Forecast remains on track with only some
minor adjustments needed based on observational data and trends.
Fair through this evening with chances for showers moving into
the southern reaches of the forecast area overnight. Milder and
muggier than last night.
A strong mid and upper level ridge over the western Atlantic
will continue along the East Coast tonight into tomorrow with
above normal heights. A pair of frontal boundaries will impact
the forecast area tonight through tomorrow.
The cold front with cooler and drier air will remain north of
the St Lawrence Valley tonight associated with a strong northern
stream mid and upper level trough. Another frontal boundary
along the periphery of the 597 decameter closed anticyclone near
the East Coast will drift northward from the Mid Atlantic
States and coastal New England tonight. Some over running light
rain or rain showers will move towards locations south and east
of the I-90 corridor and closer to the I-84 corridor after
midnight. An inverted sfc trough and weak mid-level shortwave
will enhance the lift and moisture advection with this feature.
Some weak elevated instability is indicated by the latest NAM
over the southern most zones, so a rumble or two of thunder may
possible.
Some patchy fog may form north of the area of showers, as their
likely will be a sharp cut-off in the cloud shield. A weak sfc
high will be over upstate NY and New England early in the
period. We placed some patchy fog in the forecast, and it will
be a muggy night with sfc dewpts in the upper 50s to mid 60s.
Low temps will be in the upper 50s to lower 60s over the higher
terrain and north and west of the Capital Region and mid and
upper 60s from the Capital Region south and east.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
Tomorrow...Complicated forecast with the two fronts impacting
the forecast area coupled with the weakening ridge. An influx of
deeper moisture and tropical like air mass will occur over the
southern half of the forecast area with PWATs rising to around
2.0". Further north and west of the Capital Region PWATS will be
in the 1.5-2.0" range. The higher PWATs are +2 to +3 STD DEVs
above normal based on the 12Z GEFS. Weak impulses moving along
the front south of the region could bring isolated to scattered
thunderstorms with locally heavy downpours. There are some
timing differences in the CAMs, especially with the 3-km NAMnest
and the 3-km HRRR. The 3-km NAMnest has some convection and
heavier rain showers impacting the area in the late morning into
the early afternoon especially south and east of the I-90
corridor. The 3-km HRRR is slower and more in the afternoon
period. The model soundings look tall and skinny south of
Albany. All this said, increased lift and low-level convergence
with the boundary to the south could yield periods of heavy
rain with locally heavy downpours. WPC is placing locations
south of the Capital Region /southeast Catskills, mid Hudson
Valley, southern Berkshires and NW CT/ in the Day 2 Excessive
Rainfall graphic with Marginal Risk of exceeding the FFG. The
good news is the 1-,3-hr and 6-hr FFG values are high, but
intense rainfall rates will be possible. Ponding of water on
roadways and poor drainage flooding of low-lying/urban areas
will be possible. We will also have monitor for any training.
The latest 12Z HREFS does lean to towards an increase of mean
SBCAPE values of 1000+ J/kg in the afternoon for locations south
and east of the Capital Region and the 0-6 km bulk shear
increase to 25-30 kt. Further north, the 0-6 km shear increases
to 30-40 kts with the cold front pushing southward in the
afternoon for locations north of the Capital Region, but the
instability is generally lower in the 250-750 J/kg range. The
lower instability will limit updrafts from being tall enough for
a robust severe threat. Some gusty winds may be possible from
pcpn loading. The mid level lapse rates look weak and overall,
convection from the cold front dipping southward looks isolated
to widely scattered. Sfc dewpts will be in the 60s to lower 70s.
SPC has placed the entire forecast in General Thunder at this
time. We likely will have to monitor for a marginal/isolated
severe or two.
The front makes steady progress in the afternoon and a 2nd round
of showers and thunderstorms will be possible in the late
afternoon into the early evening over the southern most zones.
High temps will likely be held down due to clouds and a moist
air mass with highs in the upper 70s to lower 80s in the valley
areas, and upper 60s to upper 70s over the higher terrain
Thu night...Isolated to scattered showers will decrease
especially before midnight over most of the forecast area. A
few could linger a little thereafter closer to the I-84 corridor
if a weak wave forms and moves along the boundary. Strong cold
advection will occur in the wake of the front with H850 temps
falling to +6C to +10C from the Capital District north and west,
and +10C to +14C south and east. It will becoming breezy from
the west to northwest at 5 to 15 mph. Humidity levels will lower
and lows will fall into the 50s with some mid and upper 40s
over the southern Adirondacks and southern Greens.
Friday-Friday night... Cold advection continues in the morning.
A broad Canadian anticyclone builds in from the Great Lakes
Region. It will be a much cooler and drier air mass. The winds
will be northwest to north at 10 to 20 mph. Sfc dewpts will fall
into the 40s to lower 50s with even some upper 30s over the
southern Adirondacks. High temps will generally be in the upper
60s to lower 70s across the lower elevations, and upper 50s to
mid 60s over the mtns. The strong subsidence from the sfc high
will yield lots of sunshine. Fri night...the winds should go
light to calm, with clear skies, as the sfc anticyclone will be
building in over the region for ideal radiational cooling
conditons. Lows will be chilly in the 40s to lower 50s with some
upper 30s possible in the southern Greens and over the southern
Dacks.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
High pressure will slowly push to our east on Saturday but will
still bring another dry and partly to mostly sunny day with highs
ranging from the 60s in the higher terrain to the low to mid-70s in
the valleys.
Unsettled weather returns late Saturday night and continues through
Sunday night as an upper-level trough (the one responsible for the
cold and snow across the Rockies earlier this week) sweeps across
the region. At the surface, low pressure over the Upper Midwest will
track northeastward with a warm front lifting northward through the
region late Saturday night through Sunday morning and a cold front
passing through Sunday night into early Monday morning. Strong lift
along the warm front should lead to some rainfall as early as Sunday
morning (though models differ on start time). As the afternoon
progresses, an increase in dew points and precipitable water values
(1.50 to 2.00 inch range) along with being in the warm sector of
this system will likely lead to additional showers and perhaps a few
thunderstorms. The rather cloudy conditions should prevent
thunderstorm activity from being too strong, but this will continue
to be monitored over the coming days. Some locally heavy rainfall
will be possible, though with the rather dry conditions across the
region, any rainfall should be beneficial. Otherwise, it will be a
breezy day with highs ranging from the mid-60s to the mid-70s.
As the cold front pushes through Monday morning, showers will come
to an end and clouds will decrease and give way to mostly clear and
dry weather for the remainder of the long term period as high
pressure returns. There could be a northwesterly breeze on Monday
behind the front. Highs Monday through Wednesday will be in the 60s
and 70s (with Tuesday likely the coolest day) with lows mainly in
the 40s (with a few 30s possible across the higher elevations).
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Conditions will be variable across the region. Lower level clouds
will move in from the south overnight into early Thursday morning
as a trough of low pressure approaches from the south with MVFR
ceilings developing. While at KGFL, MVFR conditions are expected
to develop overnight with IFR possible due to radiation fog.
Scattered showers are expected to develop/move in from the south
early Thursday morning with MVFR conditions and IFR possible at
KPOU/KPSF. Chances for showers will spread northward but with
lesser coverage as you head northward, so have addressed threat
with VCSH in KALB and KGFL TAFs. A period of MVFR ceilings are
expected at KALB and possible at KGFL.
Light and variable to calm winds through the night with a
southerly flow developing Thursday at 6 knots or less.
Outlook...
Thursday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Friday: No Operational Impact. NO SIG WX.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: Moderate Operational Impact. Chance of SHRA.
Sunday: Moderate Operational Impact. Likely SHRA...TSRA.
Sunday Night: Moderate Operational Impact. Chance of SHRA.
Monday: No Operational Impact. NO SIG WX.
&&
.FIRE WEATHER...
A warm and humid air mass will be over the region
tonight with some showers moving into locations south of the
Interstate 90 corridor after midnight. A disturbance moving along a
front south of the region will bring showers and a chance of
thunderstorms in the late morning into the afternoon from the
Capital Region south and east. A cold front will bring additional
isolated to scattered showers into the evening periods. A much
cooler and drier air mass will settle into the region Friday
into Saturday.
The RH values will increase to close to 100 percent tonight with
some patchy fog, dew formation and scattered showers. The RH
values will lower to 40 to 55 percent tomorrow afternoon with
showers and thunderstorms moving in. The RH values will increase
to 80 to 95 percent Friday morning.
The winds will light south to southwest at less than 10 mph
tonight, and shift to the west to northwest in the wake of the
cold front tomorrow afternoon into the early evening at 5 to 15
mph and will persist through Friday morning.
&&
.HYDROLOGY...
Widespread problems are not expected on the main stem rivers the
next several days.
Isolated to scattered showers and isolated thunderstorms will
be possible late tonight for locations south of the Capital
Region.
Isolated to scattered showers and a few thunderstorms will be
possible Thursday as a front moves southward north of the
Capital Region. Locations south and east of the Capital Region
with have scattered to numerous showers with a chance of
thunderstorms with locally heavy rainfall. High PWAT values will
allow for intense rainfall rates potentially exceeding an inch
or more in an hour. Ponding of water on roadways and urban and
poor drainage flooding of low-lying areas will be possible south
and east of the I-90 corridor. 1-,3-,and 6-hr FFG values remain
high due to the recent dry spell. Total rainfall may range from
a a half an inch to an inch and half south and east of the
Capital District into Thursday night for some locations.
Rainfall amounts should generally be a tenth to a quarter inch
north and west of the Capital Region.
A cooler and drier air mass builds in for Friday and Saturday
which will allow for flows to decrease.
A more widespread and soaking rainfall is possible for Sunday-
Sunday night as low pressure tracks across the region.
For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Wasula
NEAR TERM...IAA/Wasula
SHORT TERM...Wasula
LONG TERM...Rathbun
AVIATION...IAA
FIRE WEATHER...Wasula
HYDROLOGY...JLV/Wasula
Area Forecast Discussion
National Weather Service Buffalo NY
1031 PM EDT Wed Sep 9 2020
.SYNOPSIS...
Temperatures will settle back towards normal values during the next
couple days...as the stalled frontal boundary over our region will
be pushed to the south by an approaching area of high pressure. The
period will be characterized by generally fair...dry weather that
will persist through at least the start of the upcoming weekend.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
Stratus will spread south of Lake Ontario and across the North
Country in the northeasterly flow on the cool side of a frontal
boundary which is located just south of Buffalo and Rochester.
The front will lift slightly north overnight, which will cause
the stratus to move north also, but any clearing combined with
increasing moisture from the south is likely to result in fog.
HRRR guidance shows the greatest risk for dense fog across the
Niagara Frontier, but there`s also a risk for dense fog in the
Southern Tier valleys and the North County.
Otherwise, fair dry weather will be found across the majority
of the region through the period...courtesy of a ridging off the
east coast. The only blemish could be a shower or two over the
Finger Lakes Thursday afternoon and early evening. Temps will
cool through the period. Hemispheric GEM preferred through
Thursday...GFS Thursday night.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
High pressure centered over the Great Lakes Friday morning will
spread eastward into the weekend. Dry weather expected Friday into
Saturday. A northeast flow will lead to cooler than normal
temperatures Friday with highs in the upper 60s to low 70s. Winds
veer to the south-southeast Saturday and warm air advection will
move into the region from south to north. Temperatures will climb
into the mid to upper 70s Saturday.
An upper level trough will move into the western Great Lakes
Saturday night and a southerly flow will increase transporting
Atlantic moisture into the region. Models are depicting a 100+ kt
upper level jet across southern Ontario and Quebec ahead of the
trough. The eastern Great Lakes and areas to the southeast will be
located in the right entrance region. While it looks like the better
mid-level convergence will be south and east of western and north
central NY we may have a period of moderate showers with a slight
chance of thunderstorms late Saturday night across Western NY. Low
pressure will quickly move from the Mid-West to the eastern Great
Lakes/southern Ontario region Sunday morning and drag a cold front
across the region Sunday. Moderate showers will move into the North
Country into Sunday. Showers and thunderstorms will continue through
Sunday. Drier air will filter into the region Sunday night and
showers will end from west to east.
Temperatures will climb into the mid to upper 70s Sunday and into
the mid to upper 50s Saturday night and Sunday night.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
Prolonged period of quiet and dry weather appears on tap during this
period. High pressure over the Great Lakes will track southeast
and provide tranquil weather through at least midweek. Look for
highs near to a bit above normal for this period with upper 60s
to low 70s.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Satellite imagery (Nighttime Microphysics) shows stratus and IFR
or lower conditions north of a BUF-ROC-ART line late this
evening. The front will move slightly north overnight, which may
allow a brief improvement in flight conditions after 04Z.
However, any clearing also brings the risk of fog to develop,
with locally dense fog possible. Greatest concern is across the
Niagara Frontier where moisture just to the south will mix with
cooler air late tonight. Also expect fog to develop across the
Southern Tier valleys again tonight.
Conditions will gradually improve Thursday morning, giving way
to mainly VFR conditions by Thursday afternoon.
Outlook...
Thursday night...Mainly VFR.
Friday and Saturday...VFR.
Saturday night and Sunday...VFR to MVFR with the likelihood of showers
and thunderstorms.
Monday...VFR.
&&
.MARINE...
A stalled frontal boundary will remain south of the lakes
overnight. A cold front will move across the waters late
tonight into Thursday. A northerly wind will become northeast by
Thursday night. This will persist through Friday until winds
become west- southwest Friday night. Waves will increase during
this time and small craft conditions will be possible.
A southerly wind will increase Saturday and Saturday night as a
cold front approaches from the west. Showers and thunderstorms
are possible Saturday night through Sunday night. Small Craft
Advisories will be possible during this time.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.
&&
$$
SYNOPSIS...RSH
NEAR TERM...Apffel/RSH
SHORT TERM...HSK
LONG TERM...AR/HSK
AVIATION...Apffel
MARINE...Apffel/Hitchcock/TMA
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1046 PM EDT Wed Sep 9 2020
.SYNOPSIS...
A cold front will approach the region from Canada tonight,
before slowly crossing the region Thursday through Thursday
evening. Drier air follows for Friday and Saturday as high
pressure enters the region. Low pressure will pass north of New
England Sunday into early morning.
&&
.NEAR TERM /UNTIL 8 AM THURSDAY MORNING/...
1045 PM Update...
Temperatures were adjusted slightly overnight based on latest
forecast trends. These bring overnight lows down just into the
upper 50s across the north, and keeps southern and central
sections in the 60s. Most of the coast is reporting dense fog,
and this will gradually work its way north by morning.
745 PM Update...
Have extended the dense fog advisory a tier northward based on
latest HRRR and other guidance. The advisory was also extended
until 10 am for the Mid Coast based on this morning`s timing of
fog dissipation. The offshore waters may see dense fog through
almost noon tomorrow. Otherwise showers continue along a front
across southern Quebec and northern ME, and this may bring a few
sprinkles to the northern mountains overnight. It is interesting
to note that Mount Washington was 61 degrees at 7 pm, almost as
warm as our sea level observation sites.
Previous discussion...
Plenty of low level moisture will advect inland from the Gulf of
Maine on relatively light south to southwesterly winds. This
will allow for areas of dense fog to develop once again over
southern locations. Have issued a dense fog advisory for the
coast and one row of zones inland due to visibilities dropping
to a quarter mile or less. The dense fog will be more patchy
well inland.
Latest mesoscale models suggest tropical moisture off the Mid
Atlantic region may attempt to advect into far southern portions
of our region embedded within the low level south to
southwesterly flow. Latest radar imagery continues to show some
of this moisture advecting poleward towards the southern New
England coastline. Have added low chance pops for late tonight
with this feature.
It will remain muggy tonight with overnight lows mainly in the
upper 50s to lower 60s, very close to forecast dew point values.
&&
.SHORT TERM /8 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Dense fog lifts Thursday morning. Clouds expected with the
southern New England tropical moisture with scattered showers
expected south. Highest chance for rainfall will be over
southeastern New Hampshire. Over northern sections, scattered
showers are expected along and ahead of an approaching cold
front. CAPE values increase during the day, sufficiently enough
to possibly trigger a thunderstorm or two during the day.
After some scattered showers in the south Thursday evening, the
precipitation will exit off the coastline as the front shifts
offshore. Some fog may develop over and along the coastline,
however a drying trend with northwesterly winds can be expected
by late at night as high pressure builds into the region.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Early in period a frontal boundary will push offshore allowing
high pressure over the Great Lakes to push east. This will
result in rapidly clearing skies early Friday in a fresh
northerly flow. The high will rapidly push east reaching
Northern New England Friday Night. The high will move east of
the area during the day Saturday. This will result in clear
skies giving way to mid and high level clouds later in the
afternoon as low pressure moves east from SW Ontario Province.
The low will track north of the area keeping the heaviest
precipitation to the North and West of the region...however the
associated frontal systems with the low will increase the
likelihood of showers Sunday and Sunday evening. High pressure
will build back in from Southern Canada early next week. After a
relatively warm stretch expect temperatures to trend cooler and
become more seasonable.
Models: Will be initializing with the NBM. Global models are in
better than average agreement over this period. There are slight
QPF differences for Sunday but nothing significant. The
Canadian is the driest and the GFS is the wettest but all
amounts are relatively low...under a quarter of an inch south of
the mountains. The GFS is about 6 hours faster for the onset of
any showers. The NBM POPS are a bit high this far out given
that most precip events have under performed in recent weeks.
Will therefore reduce pops about 15% across the board Sunday.
Otherwise the blend is in good shape.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Short Term...Areas of IFR and LIFR conditions developing in low
clouds and dense fog along and near the coast tonight. Patchy
dense fog possible once again over the interior.
Long Term...
Generally VFR to MVFR conditions through Saturday Night.
Areas of IFR developing in showers Sunday into Sunday
night as a cold front approaches and then crosses the region.
VFR conditions return Monday as high pressure builds in. &&
.MARINE...
Short Term...Areas of dense fog will redevelop over the waters
this evening and continuing into early Thursday. Some fog to
redevelop over the waters Thursday evening.
Long Term...
Waves and wind below SCA through Sunday Morning. Waves will
build to SCA levels as southerly winds increase ahead of low
pressure to our north. A cold front will shift winds to the NW
Monday into Tuesday with waves at or above SCA levels at the end of
the fetch.
&&
.MARINE...
Short Term...Areas of dense fog will redevelop over the waters
this evening and continuing into early Thursday. Some fog to
redevelop over the waters Thursday evening.
Long Term...
Waves and wind below SCA through Sunday Morning. Waves will
build to SCA levels as southerly winds increase ahead of low
pressure to our north. A cold front will shift winds to the NW
Monday into Tuesday with waves at or above SCA levels at the end of
the fetch.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Dense Fog Advisory until 9 AM EDT Thursday for MEZ012>014-
018>026-033.
Dense Fog Advisory until 10 AM EDT Thursday for MEZ027-028.
NH...Dense Fog Advisory until 9 AM EDT Thursday for NHZ010-013-014.
MARINE...None.
&&
$$
NEAR TERM...Hanes
SHORT TERM...Cannon
LONG TERM...Lulofs
Area Forecast Discussion
National Weather Service Blacksburg VA
1002 PM EDT Wed Sep 9 2020
.SYNOPSIS...
A strong stationary front will extend from New England into the Mid
Mississippi Valley through Thursday with another weaker front along
the southeast coast of the United States, while high pressure was
over the Mid Atlantic region in between the two fronts. This weather
pattern will result in a periods of rain across the area through
Friday. The northern front may cross through the area at the end of
the week.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 1002 PM EDT Wednesday...
Intermittent pockets of showers and drizzle continue to rotate
through the area this evening. Radar continues to show most of this
out over the Piedmont back into the Roanoke and New River Valley.
The heaviest rain continues to stay to our east out over Richmond
back to the Virginia Tidewater where the front lingers. Hi-res
guidance including the HRRR and ARW continue to paint the steadiest
rain east of the area overnight as another wave of energy moves
overtop of the western Atlantic ridge. Low clouds and areas of fog
will continue to remain in place area-wide when showers are not
pivoting on through.
Dense areas of fog are expected early Thursday morning west of the
Blue Ridge thanks to some holes in the clouds allowing for better
radiational and the extra moisture overhead. The easterly component
remains though so more gray than sun in most locations Thursday at
least to start. Some sunshine may break through by mid afternoon
especially off to the west of the I-81 stretch since these locations
are on the outer periphery of the wedge. Even with that said
conditions should look fairly similar to Wednesday with passing
showers and a few diurnally driven storms especially where we can
maximize daytime heating. Overnight lows look to fall back into the
low to mid 60s out west with upper 60s and low 70s out into the
Piedmont. Highs Thursday back int0 the mid to upper 70s and low to
mid 80s.
As of 549 PM EDT Wednesday...
A gray and gloomy evening with a few pockets of light shower
and drizzle activity moving on through. Most of our shower
activity today has been confined to the east out over
Appomattox, Buckingham, Halifax, Caswell, Campbell, and
Pittsylvania counties. These areas are closest to the stalled
frontal boundary off the Virginia Tidewater and a shortwave
piece of energy in the upper flow rotating northeast around the
upper ridge over the western Atlantic. Downslope can be noted
where shower coverage has been minimized throughout the day and
a few breaks of sunshine have been allowed to poke through. Off
to the east of I-81 and out over the Piedmont southeasterly
upslope flow has allowed a rich transport of PWATS around 1.9 to
2.2 inches to work on in. For that reason went ahead to keeping
numerous showers and light to moderate pockets of rain in these
areas areas tonight with a tapering of precipitation chances to
around 20-40 percent west of the I-81 corridor. A few rumbles
of thunder cannot be ruled out the rest of this evening but as
of now the overall threat looks to be pockets of showers, low
clouds, and fog heading into the overnight hours.
Adjusted temperatures a bit to reflect where pockets of sunshine
have been noted out over the North Carolina mountains and back
across portions of southern West Virginia as well as the New River
Valley. Overall most locations continue to hang in the mid to upper
70s with upper 60s and low 70s out east over the Piedmont.
Temperatures look to fluctuate a degree or two over the next few
hours but look to remain relatively steady through the overnight
period with the clouds and excess moisture overhead. The only
exception to this would be out west over the mountain where some
breaks could be noted thanks to downslope pushing lows in to the
upper 50s and low 60s overnight.
Areas of dense fog to start Thursday morning with pockets of drizzle
and mist rolling on through. Low clouds should lift a bit by mid
morning with a few leftover showers out east according to the latest
hi-res guidance. Another shortwave looks round our ridge out over
the western ATlantic with another wave of showers and even a few
scattered thunderstorms Thursday afternoon as more tropical moisture
pumps in. High temperatures look to be similar to Wednesday with
highs in the low to mid 70s out over the mountains and mid to upper
70s to about 80 east of the Blue Ridge.
Confidence remains moderate for overall precipitation and
temperatures in the near term. Timing remains an issue overall with
the modeling on timing the waves and placement of shower and
thunderstorm activity as it rounds the ridge.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 225 PM EDT Wednesday...
The short term remains active with the region remaining on the NW
cusp of high pressure. Shortwaves within the flow, combined with
diurnal heating and ample moisture with PWATs 1.5-2.0 standard
deviations above normal will result in ample opportunities for
showers and embedded thunderstorms. While areawide totals won`t
remain very high, training and terrain influenced convection could
result in amounts greater than 1.5 inches in places. This ample
rainfall over multiple days, following rain from Thursday, will
likely lead to flooding complications.
Saturday, a backdoor front enters the region while high PWATs
remain, resulting in continued rainfall with ample cloud cover and
below average temperatures. It won`t be until Saturday night that we
start to look for an actual cold front to bring a change in the
overall weather patter.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 225 PM EDT Wednesday...
A shortwave trough to our west will get picked up and exit through
Canada on Sunday. The cold front associated with this trough will
makes it way eastward to the Mid-Atlantic Sunday afternoon, bringing
yet another round of rain.
After the front fully exits the region after Monday, drier
conditions with cooler temperatures returns. That means that the
conditions we just let go with highs in the 70s/low 80s will come
back, as well as nighttime lows making their way down into the 50s
for many.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
As of 752 PM EDT Wednesday...
Our wedge continues to hold as we remain sandwiched between a cold
front to our west over the Ohio River Valley and a stationary front
along the Carolina/Virginia coast. East to southeast flow will
continue to pump rich Atlantic moisture into the area tonight and
throughout the day Thursday. This will lead to additional pockets of
scattered showers and drizzle especially east of the Blue Ridge and
foothills through the overnight into early Thursday morning.
Overall we will continue to bounce between VFR and MVFR conditions
through this evening especially at KDAN and KLYH since they sit
closest to the coastal front. Ceilings though look to lower to
IFR/LIFR mainly after 02z/10PM tonight. Besides the low ceilings
expect areas of fog overnight through early Thursday morning
especially in those typical valley west of the Blue Ridge.
Widespread low clouds will continue as fog lifts tHursday morning.
More low clouds along with additional waves of showers and storms
heading into Thursday afternoon. Winds will remain relatively light
out of the east to southeast direction through the TAF period.
Average confidence on visibility, ceilings, precipitation, and
wind. Below average confidence on timing and placement of
diurnally driven storms within the period.
.Extended Aviation Discussion...
Extensive cloud cover and daily chances for showers and
thunderstorms are expected through the period as the Atlantic
moisture remains in place across the region resulting in a
moist, warm, humid, and unsettled weather pattern. Prolonged
periods of sub-VFR conditions are likely. Drier air may arrive
early next week.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...AMS
NEAR TERM...ET
SHORT TERM...RR
LONG TERM...RR
AVIATION...ET/KK
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
821 PM EDT Wed Sep 9 2020
.UPDATE...
Latest RAP model locates an inverted trough from the southeast
Gulf of Mexico to northeast FL that eases westward later tonight
and Thu. Deep southeasterly flow moves in behind the trough and
helps maintain a moisture rich atmosphere. Model PWAT values run
2.2 to 2.5 inches through tonight into Thu.
Afternoon showers and storms produced some gusty winds and
localized street flooding earlier but have pushed offshore...leaving
some light rain behind mainly in the north. The showers and a few
storms will continue over night as they drift slowly west...the
rain will be ending within the next couple of hours. The rest of
the night on land should be dry although there may be some brief
low cloudiness toward sunrise. Have adjusted the forecasts for the
next few hours to better reflect current and near term
conditions.
&&
.AVIATION...
10/00Z TAFs. Afternoon convection has cleared the aerodromes with
prevailing VFR with FEW-SCT low clouds under a BKN middeck.
However...there could be some OCNL BKN ST late night but will hold
at SCT. Southern terminals will see VCSH AFT 15Z then VCTS AFT
18Z for all sites. Brief MVFR TSRA 20-23Z. Light E winds become
VRB to calm over night then E or SE AFT 15Z. Winds at TPA/PIE/SRQ
shift to onshore in the afternoon.
&&
.MARINE...
An inverted trough in the eastern Gulf slowly exits to the west
as high pressure...with a relaxed gradient...builds in from the
northeast during the rest of this week. This keeps southeast and
east winds in place although shifting to onshore near the coast in
afternoon sea breezes. Isolated to scattered thunderstorms will
result in locally higher winds and seas.
&&
.Preliminary Point Temps/PoPs...
TPA 76 90 76 92 / 40 70 50 70
FMY 75 91 75 92 / 20 70 50 70
GIF 74 91 74 92 / 20 70 30 80
SRQ 75 91 75 92 / 30 70 60 60
BKV 73 91 74 92 / 40 70 50 70
SPG 76 90 76 92 / 40 70 60 60
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION/MARINE...09/Rude
UPPER AIR...42/Norman
DECISION SUPPORT...42/Norman