Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/25/24
AREA FORECAST DISCUSSION
National Weather Service Albany NY
958 PM EDT Tue Sep 24 2024
.SYNOPSIS...
The two week stretch of dry conditions over much of
eastern New York and western New England will not be allowed to
extend past this evening as showers look to spread into the region
from northwest to southeast overnight tonight. But unsettled
conditions will be short lived as yet another period of dry weather
looks to begin Friday into the upcoming weekend.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
.UPDATE...As of 0955 PM EDT, we`re beginning to see rain
showers moving into portions of Herkimer and Hamilton counties
as a band of WAA builds into central New York. Rainfall amounts
across that area have ranged from a few hundredths to near a
quarter of an inch (mainly in persistent bands of showers).
Latest CAMs including the HRRR have been handling the evolution
of showers well, so have updated POPs to reflect obs and newer
guidance over the next few hours. Previous discussion below...
.PREV DISCUSSION [0400 PM EDT]...Tranquility persists this
afternoon as part of the last day of the recent two-week stretch
of dry conditions across much of eastern New York and western
New England. Visible satellite imagery shows mostly to partly
sunny skies across the region with the most consistent coverage
south and east of Albany courtesy of easterly flow driving
coastal clouds inland. And though a cirrus shield has reached
the western edge of our CWA in advance of a low pressure system
currently situated in the Ohio Valley, a hole or minimum in
cloud coverage has existed for much of the afternoon from Albany
northward due to enhanced subsidence and possible downsloping
effects with high pressure adjacent to the northeast.
Throughout the remainder of the afternoon/evening and into the
overnight, the high over Atlantic Canada will gradually slide
south and east as upper- level ridging aloft is forced to
deamplify and also shift south and east as an upper level trough
digs into the Mississippi Valley. By tomorrow morning, the
trough looks to split as the southern portion deepens and closes
off into an upper-level cutoff low in the Mississippi Valley and
the northern portion remains a positively-tilted shortwave about
the base of an upper low in northern Canada. The aforementioned
surface low currently in the Ohio Valley will gradually track
north and east into the northeast Great Lakes/southeast Ontario
as the axis of the shortwave aloft digs farther south into the
same area. Warm air advection ahead of the attendant warm front
associated with the low paired with favored synoptic-scale
forcing for ascent at the leading edge of the shortwave will
allow showers to develop and track into the region by tonight.
Showers will spread into the region more or less from west to
east, bringing the initial accumulations of what will be much
of the region`s first accumulating rainfall in over 14 days.
Showers tonight will be relatively light in nature, impacting
areas mainly north and west of Albany. Extensive cloud cover as
a result of the advancing system will make for more mild
temperatures in comparison to last night with upper 40s to low
50s anticipated.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
Showers continue into the day Wednesday as the shortwave
propagates farther eastward and the surface low continues its
progress northward whilst the cutoff low sinks farther into the
deep south. Southwesterly flow across the area will align with
the southwest to northeast axis of moisture extending
northeastward from the Gulf of Mexico, bringing plenty of fuel
to sustain rounds of showers throughout the day and into
Wednesday night. The heavier showers look to come Wednesday
evening into Thursday morning as upper-level flow increases in
response to the deepening and closing off of the upper wave into
an upper low. Increased divergence aloft and upslope flow could
lead to some heavier downpours in higher terrain regions of the
Southwest Adirondacks and Southern Greens, but with the recent rain
deficit, there are no hydro concerns at this time. It is also
possible that some embedded thunderstorms develop Wednesday
afternoon/evening as latest CAMs are indicating some elevated
instability within the environment. However, no severe weather
is anticipated.
Showers continue into Thursday morning as a weak cold front
swings through the region, but gradually begin to wane in
spatial coverage as the upper low moves east into southeast
Quebec, taking with it the better forcing. By Thursday night,
primarily dry conditions will be reinforced across the region as
heights increase in the wake of the upper low with high pressure
ridging building over the Midwest and into Ontario.
High temperatures Wednesday will be the cooler of the period
with extensive cloud cover and rain-cooled air, reaching only
the mid 50s to mid 60s. Low temperatures Wednesday night will
only dip into the low to mid 50s with pockets of upper 40s above
1500 ft and upper 50s in valley areas. Highs then warm Thursday
to the mid/upper 60s to low 70s with pockets of low 60s across
higher terrain regions. Thursday night will feature lows in the
low to upper 50s with upper 40s in the Southwest Adirondacks and
highest peaks of the Eastern Catskills and Southern Greens.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
Another prolonged period of dry weather is anticipated across
the long term forecast period as upper-level ridging builds in
across the region Friday into Saturday and remains in place
through early next week as an Omega block sets up Monday into
Tuesday. Though the closed low in the Deep South will track
north through the Mississippi Valley through the weekend, the
high pressure ridging it encounters will keep it at bay, leading
to little to no impact for our region.
High temperatures will
be fairly similar throughout the period with mid/upper 60s to
low 70s across much of the region outside of pockets of low 60s
possible across higher terrain. Low temperatures will generally
fall to the upper 40s to low 50s each night of the period.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Through 00z Thursday...VFR conditions to start the period will
slowly deteriorate through the night, as low clouds and chances
of rain showers increase with an approaching system. The first
chance will come around 25.10z mainly at ALB/GFL as low-level
lift increases, with MVFR ceilings and visibilities also
expected. Guidance is in agreement of a brief break in activity
through midday, though MVFR and scattered IFR ceilings will
persist at all terminals. A more widespread moderate to heavy
rain will arrive towards the end of the TAF cycle and will be
accompanied by low-end MVFR to IFR conditions, though these
should hold off until after 26.00z.
The winds will be light from the east to southeast at less than
10 KT tonight, and then will be southeasterly at 5-10 KT after
12Z Wednesday.
Outlook...
Wednesday Night: High Operational Impact. Likely SHRA...TSRA.
Thursday: High Operational Impact. Likely SHRA...TSRA.
Thursday Night: Moderate Operational Impact. Chance of SHRA.
Friday: No Operational Impact. NO SIG WX.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
&&
.CLIMATE...
Having last recorded measurable precipitation on September 9,
the dry spell in Albany reached 14 days on Monday, September 23.
This is the first two-week dry spell in Albany since May 11-25,
2021, when a trace of precipitation was observed over 15 days.
Furthermore, every day in the current dry spell has seen zero
precipitation, marking the first absolute dry spell of at least
14 days since October 4-26, 1963.
Tuesday, September 24 is expected to extend the dry spell to 15
days before widespread rain ends the streak on Wednesday.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Gant
NEAR TERM...Gant/Speck
SHORT TERM...Gant
LONG TERM...Gant
AVIATION...Speck
CLIMATE...Picard
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
645 PM CDT Tue Sep 24 2024
...New AVIATION...
.SHORT TERM...
(Tonight through Wednesday night)
Issued at 319 PM CDT Tue Sep 24 2024
Through this evening...Very localized convection has fired up in
southern Cameron County...right over Brownsville. Convective-
allowing models (CAMs) are not too bullish on too much additional
development beyond this area...will need to keep an eye a bit
farther west along the river but that`s about it. Better activity
in the Gulf should stay there due to sea breeze stability over the
coastal/near coastal areas. Model blends actually show this fairly
well and updated the forecast to cover...with a pocket of likely
where it`s raining now and lower (isolated/scattered) elsewhere
inland except for the upper Valley/Rio Grande Plains. Another area
to watch is Kenedy/Brooks which is closer to an area of higher
coverage of showers this afternoon.
For tonight, skies will clear as they have in recent nights and
winds will lay down to near calm. The one exception is late at
night near the coast, as another round of isolated to scattered
showers over the Gulf should edge toward shore. There are some hints
of deeper moisture (compared with recent nights) so could see a few
more late night clouds inland...but this is not explicitly forecast
right now. Temperatures will be largely unchanged from recent
overnights...plenty muggy with morning lows in the mid to upper 70s.
For Wednesday...models have backed down a bit with rain chances and
QPF...but as northwest flow aloft becomes established by late in the
day we`ll need to watch the approach of a shear axis on the tail of
the actual trough which dives into the lower Mississippi Valley
toward evening. For now...maintained mainly sea-breeze driven
convection, pulling the rain chances away from the nearshore/coastal
areas by mid to late afternoon which is common. Temperatures and
heat index should be similar to today except if/when/where it rains.
The aforementioned shear axis moves across the region overnight
and the forecast could be a bit tricky. Global models are
diurnally bearish...but CAMs are a bit more bullish including the
HRRR and HRW which show band(s) along/just ahead of the wind shift
(front) that is expected to pass and bring drier (lower humidity)
conditions beginning Thursday. Exactly where any stronger cells
may develop is unclear but the threat is there. For now a stripe
of 20-30 percent chances moving from north to south through the
night, which should exit the U.S. between 4 and 7 AM, if not
sooner. The onset of the drier air will filter across the northern
ranchlands and perhaps reach the RGV by daybreak on slightly
increased northerly winds...and low temperatures will end up near
seasonal averages (70 to lower 70s) by daybreak.
Lastly, as Tropical Cyclone Helene moves toward the Yucatan Channel
and begins its potential rapid intensification cycle overnight
Wednesday, coastal impacts may be delayed until the start of
Thursday (long term period). That said, tides remain well above
predicted levels...which are in "King" Tide mode and among the
highest levels of the calendar year. However, the lack of wave
energy should keep coastal flooding (i.e. water up to the dunes)
out of the picture at the early Wednesday morning high tide...and
probably just out of the picture before daybreak Thursday though
we`ll need to keep tabs for a possible Coastal Flood Statement
then, before we begin to consider Advisories Thursday into Friday
due to the back swell from Helene.
&&
.LONG TERM...
(Thursday through next Tuesday)
Issued at 319 PM CDT Tue Sep 24 2024
Key Messages:
-Tropical Storm/Hurricane Helene to have little impact to Deep South
Texas and the Rio Grande valley.
-A cold front will move through the region late week bringing a bit
of relief from the oppressive heat.
The main story and impact to Deep South Texas and the Rio Grande
Valley for the long term period will be the approach and passing of
a cold front. On Thursday, a midlevel low pressure system located
across the middle Mississippi Valley will begin to ingest what will
be Hurricane Helene and cause the aforementioned low to linger
across the middle/lower Mississippi Valley through the end of the
week. The low finally drifts northeast through the weekend and into
early next week with high pressure returning to Deep South Texas a
dry conditions into early week.
At the surface the aforementioned low will drag a cold front through
the CWA Thursday. Forecast CAPE values remain around 1000 J/kg and
PWATs between 1.50 and 1.75 inches on Thursday morning we could see
some isolated to scattered showers and thunderstorms with the
potential for some brief heavy rainfall in spots as the front moves
through the CWA. Rain chances will be confined to the lower Valley
and along the coast with POPs under 30%. In wake of the FROPA, much
drier air will filter into the region.
Along the coast, the combination of the frontal passage and the
arrival of long period swell from Helene will result in increased
wave heights and adverse beach conditions Thursday and Friday.
Enhanced rip current risk and minor coastal flooding will be
possible at beaches along the Lower Texas Coast.
As for temperatures, we won`t see much relief from the warm
temperatures (in some respects) with highs remaining in the low to
mid 90s, but with less humidity and lower dewpoints heat indices
will stay below 100 degrees through the forecast period.
&&
.AVIATION...
(00Z TAFS)
Issued at 625 PM CDT Tue Sep 24 2024
Currently, MFE and HRL are sitting under clear skies while BRO is
experiencing broken VFR conditions due to earlier convection.
Winds at all terminals are out of the east-southeast and generally
ranging from between 8 to 12 knots. Overnight, winds are expected
to diminish to light and variable along with scattered clouds at
VFR, with less coverage over MFE, and a few MVFR clouds.
Following sunrise tomorrow morning, scattered clouds, at VFR
levels, will persist and chances of vicinity showers will
increase by the late morning hours for HRL and BRO. A PROB30 has
been added for all terminals for the chance of isolated to
scattered showers and thunderstorms between 16Z to 20Z for HRL and
BRO as well as between 19Z and 22Z for MFE, due to elevated
moisture being lifted along the seabreeze boundary into the
afternoon hours tomorrow. Clouds should remain at VFR tomorrow
with light to gentle east-northeast winds.
&&
.MARINE...
Issued at 319 PM CDT Tue Sep 24 2024
Now through Wednesday Night: Outside of Isolated to scattered
convection, light winds and slight seas will be the rule through
most of the period through Wednesday. Wednesday evening will be
fine as well, but conditions could begin deteriorating overnight,
first from a small chance (10 to 20 percent) of a band of
showers/embedded thunderstorms to press south through the waters
during the late evening through postThursday through Monday...What will be Hurricane Helene and the
passage of a cold front will likely lead somewhat adverse conditons
to start the period. As a cold front moves through the waters off
the lower Texas coast on Thursday, isolated to scattered showers and
thunderstorms will be possible along with increased winds Thursday
into Friday. At the same time swell from Helene will arrive on
Thursday as well leading to elevated seas, most likely on the
offshore Gulf waters. Small Craft Should Exercise Caution headlines
or Small Craft Advisories may be needed for the Gulf waters Thursday
and Friday as wave heights look to reach 6-7 feet. Seas are expected
to subside over the weekend, with favorable marine conditions
prevailing through the remainder of the period. midnight hours.
Soon after, winds turn northerly and increase toward 15
knots...while at the same time the first note of easterly swell
and building seas may arrive in 20-60 nm leg before daybreak. For
now...seas are forecast to increase to near 4 feet at that time,
likely a combination of wind wave and early arrival of easterly
swell.
Thursday through Monday...What will be Hurricane Helene and the
passage of a cold front will likely lead somewhat adverse conditons
to start the period. As a cold front moves through the waters off
the lower Texas coast on Thursday, isolated to scattered showers and
thunderstorms will be possible along with increased winds Thursday
into Friday. At the same time swell from Helene will arrive on
Thursday as well leading to elevated seas, most likely on the
offshore Gulf waters. Small Craft Should Exercise Caution headlines
or Small Craft Advisories may be needed for the Gulf waters Thursday
and Friday as wave heights look to reach 6-7 feet. Seas are expected
to subside over the weekend, with favorable marine conditions
prevailing through the remainder of the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE 78 93 75 89 / 20 40 30 30
HARLINGEN 74 94 71 90 / 10 40 30 20
MCALLEN 78 96 75 94 / 10 30 30 10
RIO GRANDE CITY 75 94 73 92 / 10 30 30 10
SOUTH PADRE ISLAND 81 87 79 86 / 20 40 40 30
BAYVIEW/PORT ISABEL 77 91 74 87 / 20 40 40 20
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
SHORT TERM...52-Goldsmith
LONG TERM....68-McGinnis
AVIATION...65-Irish
Area Forecast Discussion
National Weather Service Charleston SC
1106 PM EDT Tue Sep 24 2024
.SYNOPSIS...
High pressure will linger across the region through Wednesday.
A tropical cyclone is forecast to track northward across the
Gulf of Mexico, then move inland late week across portions of
Florida, Georgia, and possibly South Carolina. Drier weather
then arrives for the weekend.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Earlier showers trying to develop in the coastal waters have
since fizzled with quiet weather anticipated overnight. No
significant changes made to the overnight forecast.
Previous discussion...
Quiet weather out there this evening and that will remain the
case through the overnight as mid level ridging and surface high
pressure remaining along the southeast coast. That said, there
are a few showers moving through the outer waters within the
larger scale southeast flow. HRRR guidance does drive a few
showers into coastal areas overnight. Not prepared to add any
precip chances to the going forecast at this juncture, but will
keep an eye on trends. Low temperatures are forecast to range
from near 70 inland to the mid to upper 70s along the coast.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
Wednesday: The upper level ridge that was over the Pacific Northwest
on Tuesday will translate east towards the Four Corners region with
a trough axis centered across the Great Lakes. Meanwhile, energy
that was near MN/ IA earlier this week will be diving south towards
AR with wave breaking starting to occur. As this happens, the energy
will break off into a closed upper level low and become quasi-
stationary over AR. Towards SC/ GA, a mid-level ridge will nudge
east, but still keep the area dry as a subsidence inversion remains
around 800/ 900 mb. PWATs are also forecast to be around or below
1.50" with substantial mid level dry air in place. At this time
though, Helene will likely be a hurricane and turn to the north as
it begins to feel the influence of the mid level low (or weakness).
Widespread cirrus will filter into the region and thicken. Expect
high temperatures in the mid to upper 80s with low temperatures in
the lower to mid 70s.
Thursday and Friday: All attention then turns to Tropical Storm
Helene on Thursday as it begins to accelerate to the north/
northeast or towards the Florida coastline. Rapid intensification of
Helene is expected Thursday due to warm Gulf of Mexico water and
little in the way of upper level shear. The National Hurricane
Center is forecasting Helene to make landfall as a major hurricane
along the Big Bend region of Florida Thursday evening. During the
day Thursday, cloud bases will continue to lower as showers
overspread the region from the southwest. Helene will bring multiple
hazards to GA and SC. For full details, please refer the the HLS.
Wind: A tropical storm watch is now in effect for all GA zones and
GA marine zones. Peak wind gusts will likely occur Thursday night
into early Friday morning as Helene moves north across central GA.
Wind gusts across SC will likely remain mostly below Tropical Storm
Force at this time. Therefore we opted only for a Tropical Storm
Watch across GA.
Tornadoes: As Helene passes west of the region Thursday night,
hodographs rapidly elongate with an impressive amount of instability
forecast for a tropical cyclone. Both the GFS and NAM have MLCAPE
values at 500 J/kg or greater with Helicity values around 300 m2/s2.
Critical angles are also near 90 degrees, which would make most of
the vorticity streamwise, or suitable for the development of
tropical tornadoes. As such, the SPC has the area in a slight risk
for Thursday into Friday.
Storm Surge: Currently surge values are in the 1 - 3 ft range MHHW.
As such, coastal flood products might be required. More on this can
be found in the Tides/ Coastal Flooding section.
Flooding Rainfall: As mentioned above, multiple rounds of showers or
rainbands in association with Helene will begin to impact the area
Thursday morning (esp towards GA). By Thursday afternoon, rainfall
will have spread over the entire region. Showers and a isolated
rumble of thunder will then persist through Thursday night into
early Friday morning. Helene will continue to head north and be
across central/ northern GA by sunrise Friday morning. At this
time, rainfall will start to come to an end across coastal GA
and SC. Rainfall totals of 3 - 5" are possible for GA with 2 -
4" across SC.
Helene will be across northern GA and SC Friday morning with
dry air wrapping around the southern flank of the storm. As this
occurs, rainfall will come to an abrupt end Friday after
sunrise with breaks in the clouds appearing. Southwest winds
will be gusty at times with temperatures warming into the upper
80s.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Friday night into Saturday, long term guidance indicates that the
forecast area will remain between a closed mid-level low over the
Mississippi River Valley and a 592 DM ridge over the Bahamas. Dry air
in the wake of the remnants of Helene is forecast to drift
northward, with a stream of moisture flowing NE between the two mid-
level features across the forecast area. The moisture should yield
some gradually increase in cloud cover with isolated showers across
extreme SE GA. High temperatures should favor values in the mid to
upper 80s.
Sunday through Tuesday: The closed mid-level low will shift east
over the Ohio River Valley on Sunday. Then opening into a wave
across the east coast early next week. Isolated to scattered showers
and thunderstorms will remain across the forecast area through the
period, especially during the afternoon and evening. High
temperatures are forecast to range between 80 to 85 degrees with
lows between 65 to 70.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
00Z TAFs: VFR. Winds will remain steady from the SSE although
tend to weaken during the overnight hours. Some gustiness will
develop during the day Wednesday with gusts to around 20 knots
possible.
Extended Aviation Outlook:
Wednesday: All terminals VFR with winds out of the southeast.
Thursday: Hurricane Helene will be across the northeast Gulf of
Mexico Thursday morning heading to the north/ northeast. Initially,
all terminals will be VFR in the morning hours with high clouds
thickening and bases slowly lowering. By the afternoon hours, MVFR
conditions are likely at KSAV and KCHS. Transient IFR cigs will then
be possible by the evening hours as precipitation from Helene
spreads over the entire region. Visibilities will also be reduced to
IFR or lower at times due to the heavy rainfall. Restrictions in
cigs, vsbys, heavy rain, and gusty winds will then persist Thursday
evening into early Friday morning.
Friday: Helene will quickly start to pull away from the region with
a return to VFR conditions. Southwest winds will be gusty at times.
Saturday and Sunday: VFR conditions. No precipitation is expected on
Saturday with a slight chance of showers and thunderstorms on
Sunday.
&&
.MARINE...
Tonight, a ridge of high pressure will southeast winds around 10 kts
across the marine zones. Seas are forecast to range between 3-4 ft.
Wednesday: Broad high pressure offshore will result in southeast
winds around 15 kt. Seas will average 2-3 ft for the nearshore
waters out 20 nm and 3-4 ft for the outer GA waters from 20-60 nm.
Conditions will begin to deteriorate Wednesday night ahead of an
approaching potential tropical cyclone in the southern Gulf of
Mexico.
Thursday through Friday: Expect dangerous marine conditions as a
northward moving tropical system in the Gulf of Mexico strengthens.
Fine details are likely to change depending on the exact track and
strength of the system. At this juncture, guidance indicates ESE
gusts could range between 25-30 kt by Thursday morning. The tropical
cyclone is expected to track inland and make it closest approach
late Thursday night/early Friday, which is when tropical storm force
gusts or greater are likely across the local waters. A Tropical
Storm Watch has been issued for the GA waters. Tornadic waterspouts
will also be possible during this time frame, in addition to bands
of heavy rain. Seas are expected to peak between 8-13 ft within 20
nm and 14-17 ft over the outer GA waters from 20-60 nm late Thursday
night. Conditions will begin to improve Friday night.
Saturday through Sunday: As the tropical system rapidly weakens to
our north, seas will drop to 2-3 ft with westerly winds shifting out
of the north around 10-15 kt.
High Surf and Rip Currents:
Wednesday: Onshore winds and swells with 10 to 11 seconds will
develop along the Ga Coast. Local calculation and rip current MOS
support a moderate risk for the GA coast.
Breaking waves of 5 feet or greater are likely to occur at the
beaches Thursday into Thursday night. A High Surf Advisory will
likely be needed for all area beaches. Significant beach erosion is
likely to occur during this time. A high risk for rip currents has
been posted for the SC/GA coast on Thursday. Additionally, an
elevated risk for rip currents is possible Friday with lingering
gusty winds, large breakers, and long period swells.
&&
.TIDES/COASTAL FLOODING...
On Thursday, strengthening onshore winds could lead to an increasing
tidal departure, with some coastal flooding possible along the
Charleston and Colleton County coasts Thursday afternoon. The threat
for coastal flooding is then expected for the entire coast through
the end of the week due to impacts from a tropical cyclone. Storm
surge inundation of 1 to 3 ft is possible along the coast of
southeast Georgia and the South Carolina Lowcountry.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Tropical Storm Watch for GAZ087-088-099>101-114>119-137>141.
SC...None.
MARINE...Tropical Storm Watch for AMZ354-374.
&&
$$
NEAR TERM...Adam
SHORT TERM...Haines
LONG TERM...NED
AVIATION...Adam/Haines
MARINE...NED
Area Forecast Discussion
National Weather Service Indianapolis IN
943 PM EDT Tue Sep 24 2024
.KEY MESSAGES...
- Patchy fog developing overnight
- Seasonable temperatures for much of this week with highs in the
70s and lows in the upper 50s and 60s
- Potential for more rain late week into the weekend from tropical
remnants. Many uncertainties remain on location and amounts of
rainfall
&&
.FORECAST UPDATE...
Issued at 943 PM EDT Tue Sep 24 2024
The cold front has moved away to the east of the region this evening
with only a few small pockets of showers left and these are rapidly
dissipating as well. Mostly cloudy skies remained behind the front
with temperatures at 01Z in the mid and upper 60s.
Much of the rest of the night will shift focus to the potential for
fog to develop as W/NW winds lighten. Model soundings hint at near
saturated conditions persisting within the boundary layer as drier
air aloft builds in. Expect that to manifest as a reexpansion of
lower stratocu as the night progresses...but there remains enough
breaks in the clouds that the patchy fog potential cannot be ignored
with special emphasis on locations that received rainfall earlier
today. Will introduce fog after 06Z and maintain it through daybreak
with improvements by mid morning Wednesday.
Lows will fall into the upper 50s and lower 60s which the current
forecast has covered well. Zone and grid updates out.
&&
.MESOSCALE UPDATE...
Issued at 447 PM EDT Tue Sep 24 2024
Central Indiana remains in a broad warm sector ahead of a deepening
surface low this afternoon. Broad lift and 1000-2000 J/kg of
instability within this warm sector has allowed for scattered
showers and thunderstorms to develop. This has primarily been
focused along two advancing boundaries; one over far eastern Indiana
and one along the I-69 corridor.
Overall shear has been supportive of updraft development, but
greatest effective shear has remained over southern Indiana and KY.
This could move northward with time though as a dry slot has been
noted via visible satellite imagery, of which could help deepen the
instability layer allowing for storms to tap into greater shear
aloft. 0-1 km shear has slowly been increasing as well, as the
surface low deepens increase low level backing of the winds. This
low level shear has a greater concentration over N/E IN and OH.
All of this said, central Indiana still looks to remain in a
marginal threat for isolated downbursts within organized updrafts,
with a slightly greater threat east of central Indiana. If the
greater deep shear is able to match up with the low level shear,
an increased threat for isolated tornadoes will be possible, but
this looks to be more likely over portions of OH. After the line,
currently over the I-69 corridor, passes, the severe threat
should also end (around 7-8 PM EDT).
&&
.SHORT TERM (This evening through Wednesday)...
Issued at 224 PM EDT Tue Sep 24 2024
Synopsis:
Surface analysis early this afternoon shows low pressure in place
over northwest IN. This was resulting in cyclonic lower level flow
across Central Indiana. Our forecast area resided within the warm
sector with south to southeast surface winds across the area. A weak
surface trough axis was found pivoting around the low over western
Central Indiana. Radar this afternoon shows the development of
instability convective showers and storms across Central Indiana.
Dew points remained moist, in the mid 60s to near 70. Aloft, a deep
upper trough was in place over the northern plains, extending south
to the southern plains states. This was resulting in southwest flow
over Central Indiana aloft.
Overnight -
Fog will be expected to develop overnight. Light winds are expected
to arrive, and lower level residual moisture will remain present.
Dew point depressions overnight are expected to fall to 0-2F.
Furthermore, there is a lack of an arrival of dry air as dew points
only fall to around 60 overnight. Thus fog development is expected,
particularly away from the urban heat island of Indianapolis. Expect
overnight lows to fall to the upper 50s to lower 60s.
Wednesday -
Forecast soundings suggest good subsidence an drying within the mid
levels on Wednesday, however they do suggest to saturation during
the afternoon hours as convective temps are reached. Meanwhile
aloft, the upper trough over the plains is expected to push east
toward the Ohio valley and surface high pressure tries to build over
Indiana. All of this could lead to some shallow rain shower
development and CU development. Confidence for partly to mostly
cloudy skies due to CU development is high, however, confidence for
rain showers is low and any precip should remain rather light. HRRR
hints at a few showers across the area, but mainly to the northwest,
perhaps lake enhanced, coming off Lake Michigan. Thus will include
slight chances for afternoon shower across much of the area.
Confidence in this is quite low. Highs on Wednesday should reach the
middle to upper 70s.
&&
.LONG TERM (Wednesday night through Tuesday)...
Issued at 224 PM EDT Tue Sep 24 2024
Synoptic Pattern:
Currently, central Indiana is positioned upstream of an amplified
trough, with an associated week low pressure system. This will
allow for marginal baroclinicity in the low levels, and a weak push
of cooler air following its departure.
In the upper levels, the ridge over the Inter-Mountain West will
amplify, creating strong AVA and height rises over the Great Lakes
region. In return, the aforementioned low will become "cut-off" from
the polar jet and become stationary over the Ozarks/Mid-Mississippi
Valley. This should place central Indiana in a rather mundane, cool
pattern through mid-week, with the majority of the forcing from the
cut off low staying south/west of central Indiana.
The pattern will begin to shift late week as a tropical system
plunges into the CONUS. With the cutoff low over AR/MO, and a high
over the Mid-Atlantic, steering flow should push the warm-core low
north into the Tennessee Valley late Thursday, where it will begin
extra-tropical transition. As this process begins, it will also
interact with the cut-off low, creating a Fujiwara effect as the
vort maxes collide. This should push the remnants of the tropical
low westward into the Ohio Valley. There is still a lot of
uncertainty on the impact of the antecedent high pressure over the
Great Lakes and strength of the tropical low leading to low
confidence in the overall impacts to central Indiana.
Temperature/Cloud Cover/Wind:
With the low becoming cutoff, very little air mass movement will
take place mid week, keeping 850mb temperatures essentially
unchanged. This, along with mostly cloudy skies will lead to
deamplified diurnal swings with highs in the low to mid 70s and lows
in the upper 50s to low 60s.
As the tropical low nears later in the week, dew points and 850mb
temperatures are expected to increase, but surface temperatures will
likely stay in the 70s with continued cloud cover and increasing
rain chances. Pockets of 80s cannot be ruled out, but most of the
region should stay in the 70s through Sunday.
A tightening pressure gradient on the northward portion of the
tropical low should lead to greater overall winds over the Ohio
Valley Friday and potentially Saturday. Current expectation is for
sustained between 15-20mph with gusts upwards of 30mph, but this
could change depending on the tropical low`s strength and
location.
Precipitation:
As mentioned, central Indiana will be positioned in the threshold
between low pressure to the SW and high pressure to the north. This
should limit moisture transport northward and keep central Indiana
mostly dry through Thursday. Still, with the low positioned close
enough to the Ohio Valley, a few stray/isolated light showers cannot
be ruled out.
This changes for Friday onward as the tropical low nears from the
S/SE. There is still a lot of uncertainty on timing and amounts, but
trends are increasing overall chances for rainfall Friday and
Saturday. Precipitation chances continue through Monday of next week
with generally low pressure remaining over the region, but
uncertainty is too high Sunday onward for confidence in rain
occurring.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 641 PM EDT Tue Sep 24 2024
Impacts:
- Ceilings dropping to MVFR tonight and possibly into IFR early
Wednesday morning
- Fog possible overnight through Wednesday morning
- VFR ceilings returning by Wednesday afternoon
Discussion:
A cold front has passed to the east of all of the terminals early
this evening with most of the lingering showers moving away and
diminishing. Drier air will briefly filter in through the evening
but expect low clouds to settle back in as deep moisture lingers
within the boundary layer through the night. The combination of
light W/NW flow and the low level moisture also supports the
development of fog overnight through daybreak Wednesday but
confidence is lower in just how widespread and low visibilities may
get. Keeping visibilities mainly in the 2-4SM range predawn through
the first half of the morning Wednesday.
Weak high pressure builds into the area Wednesday but low level
moisture will persist with cooler air aloft. Expect ceilings to lift
to a decent VFR cu field for the afternoon. Northwest winds will be
less than 10kts on Wednesday.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
UPDATE...Ryan
SHORT TERM...Puma
LONG TERM...Updike
AVIATION...Ryan
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
642 PM CDT Tue Sep 24 2024
.KEY MESSAGES...
- Patchy fog may develop tonight and become locally dense into
early Wednesday.
- Chances for periodic showers return Friday night into early
next week, but confidence in specifics remains low.
&&
.DISCUSSION...
Issued at 300 PM CDT Tue Sep 24 2024
Through Wednesday Night:
A partially lake-induced or enhanced MCV earlier resulted in
focused pockets of heavy rain and localized flooding into
portions of the Chicago metro through the early afternoon. With
efficient warm-rain processes ongoing, the lingering shower
activity focused east of the I-355 corridor will continue to
produce occasional downpours over the next couple of hours. With
this being said, thankfully, the feared more pronounced lake
induced meso-low developed over Lake Michigan, which will in all
likelihood keep any additional torrential rates safely off to
the east.
Lake effect showers should eventually get going tonight into
Wednesday morning for portions of northwest Indiana (possibly
brushing the Chicago shore), though we remain skeptical of the
more bullish HRRR depictions and suspect it`s overdoing
instability. The official forecast held onto chance (~30%) PoPs
near the lake in Porter County given the current forecast wind
directions and orientation of lake enhanced convergence. Spotty
shower activity could then expand inland into northwest Indiana
Wednesday before dissipating by or during the afternoon.
Aside from the precip. trends, have some concern for fog
development overnight, especially where clouds are able to
sufficiently clear (favoring interior northern IL). It isn`t a
very favorable fog setup due to moderate northerly flow aloft
above the inversion. However, given the return of rain over the
past few days and light surface winds tonight, will need to
monitor for patchy ground fog development, some of which may be
locally dense. Any fog should erode quickly Wednesday morning.
The rest of Wednesday and Wednesday night will be quiet, with
seasonably mild temperatures (low-mid 70s highs) Wednesday
afternoon and a relatively cool Wednesday night. Expecting dew
points to mix out Wednesday afternoon, and with light/calm winds
and clear skies Wednesday night, this should set up favorable
radiational cooling conditions. Forecast lows are in the upper
40s to lower 50s outside of Chicago and mid 50s to around 60F in
and near the city. Some concern exists for fog development
Wednesday night as well, though will let the midnight shift take
a look at this potential.
Castro
Thursday through Tuesday:
A complex evolution to the synoptic weather pattern continues
to limit forecast confidence for the long term forecast period,
although some trends and clustering across the guidance/ensemble
suite have been noted today. The latest multi-model consensus seems
to suggest that much--if not all of--our forecast area may see
little/no precipitation through at least into Friday evening.
By Thursday, a trough will have been pinched off from the jet
stream and become a closed upper-level low centered over or just
east of the Ozarks. To its north, the axis of a high-amplitude
ridge will be encroaching upon the western Great Lakes, while to
its southeast, soon-to-be Hurricane Helene will be on final
approach to making landfall along the Florida Gulf Coast. With
the influence of the ridge in our region on Thursday, we will,
in all likelihood, be treated to dry conditions and near to
slightly above normal temperatures with highs in the mid to
perhaps upper 70s (coolest near the lake).
After making landfall, Helene will encounter the upper low and
likely engage in a Fujiwhara-like interaction that will see the
tropical cyclone rapidly get torn apart with its remnants then
getting slung anticyclonically around the low and eventually
absorbed into the low itself. While there is still quite a bit
of spread exhibited in the latest suite of deterministic and
ensemble forecast guidance regarding exactly how this interaction
will play out, there seems to be growing support for most or
all of our forecast area remaining dry on Friday due to either
1.) Helene having a slower forward motion and making landfall
later and/or 2.) the continued presence of the ridge suppressing
precipitation associated with both cyclones to the south.
There`s enough of a QPF signal in the Grand Ensemble to warrant
not yanking the NBM`s PoPs for Friday in our far southern CWA
just yet, but did end up lowering them once again. Regardless
of exactly how Helene interacts with the upper low, tightening
pressure fields in the vicinity of these two interacting systems
will yield a period of breezy northeasterly winds Friday into
Saturday that will induce high wave action on Lake Michigan,
leading to dangerous conditions along the lakeshore.
Saturday onwards remains a fairly big question mark with
respect to precipitation owing to dependencies pertaining to the
aforementioned synoptic-scale interaction. In one possible
scenario, we could see rain showers on Saturday as Helene`s
remnants get whipped from east to west, then see daily periodic
rain showers heading into next week as the upper low continues
to meander around nearby.
Alternatively, if Helene and the upper low meet up farther to
the east, or if the upper-level ridge ends up being stronger
than expected and continues to keep everything suppressed to the
south, then the upper low could remain bottled up well to our
south or southeast through early next week, keeping its
associated precipitation away from our forecast area.
There are several other possible "middle ground" outcomes as
well, but with how difficult it is to model such a complex
atmospheric interaction, it will still probably take at least
another day or two for us to gain some more clarity as to
whether or when it will actually rain this weekend into early
next week. For now, have continued to leave the NBM`s broad-
brushed slight chance and chance PoPs for this time frame
largely untouched. A fairly strong cold front passage pegged for
Monday night into Tuesday may then bring a true taste of
autumnal temperatures into mid next week.
Carlaw/Ogorek
&&
.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 642 PM CDT Tue Sep 24 2024
An upper-level low over southern Lake Michigan will exit to the
east tonight, allowing for gradually improving conditions.
Scattered areas of -RADZ will persist for a few more hours, with
associated brief periods of sub-VFR visibility. Low-end MVFR
ceilings with pockets of IFR ceilings will slowly lift into
high-end MVFR levels through the night before becoming SCT VFR
by Wednesday morning. Outlying sites (RFD, DPA, and GYY) may see
MVFR BR develop overnight, with a low (20%) chance for MIFG
with IFR/LIFR visibility.
Winds will remain in the NW quadrant around or less than 10
knots through Wednesday, with the exception of a NE wind shift
with a lake breeze at ORD/MDW late Wednesday afternoon.
Kluber
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
Visit us at weather.gov/chicago
Area Forecast Discussion
National Weather Service Raleigh NC
1055 PM EDT Tue Sep 24 2024
.SYNOPSIS...
Mid-level disturbances, in moist, southwesterly flow aloft, will
interact with a stalled surface front that will weaken over the
Carolinas and VA through mid-week. Tropical Cyclone Helene is
forecast to make landfall in the Florida Big Bend late Thursday,
then move quickly north, while weakening, through the southern
Appalachians and OH Valley Friday and Friday night.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 1055 PM Tuesday...
A stationary front separating dew points in the upper-60s from dew
points in the lower-to-mid-70s currently stretches from between KTDF
and KRDU SE to between KRWI and KGSB. The SBCAPE gradient on SPC
mesoanalysis also depicts the front well, as far NE zones are very
stable while south and west of the front has SBCAPE as high as 1500
J/kg. The air mass is very moist as well, as there is deep S/SW flow
aloft between offshore ridging and a mid-level low centered over
northern Missouri. 925-850 mb moisture transport is maximized
directly over central NC, and PW values are in the 1.7 to 2 inch
range.
Moisture interacting with the aforementioned stalled front has been
bringing lines and clusters of heavy showers and storms training
across parts of the northern and western Piedmont this evening. One
line is near the VA border that will be moving ESE into Person,
Granville, Vance and Warren counties over the next few hours. A
cluster of showers and storms to the SW of the Triangle will be
moving NE into those urban areas shortly, and additional rounds of
heavy rain currently over SW NC and NW SC will move ENE across the
northern Piedmont overnight. Latest HRRR runs indicate the greatest
threat of heavy rain will be from KRDU to the north and west, which
is where a Slight Risk (level 2 of 4) of excessive rainfall is in
effect. It won`t take much rain to get flash flooding, as some
localized spots have already received as much as 1 to 3 inches this
evening. Additional localized amounts of 1 to 3 inches will be
possible where training occurs, and very localized amounts exceeding
this can`t even be ruled out. Probabilities of heavy rain begin to
decrease after 06z as instability wanes, but some convection is
likely to persist in this corridor through 12z, and with already
saturated ground, a threat of flash flooding will continue. For
these reasons, a Flood Watch is in effect for our tier of counties
bordering VA (plus Durham, Wake and Franklin counties) from now
until 8 AM tomorrow morning.
Farther south and east away from the front, a mostly dry night is
expected, but an isolated shower can`t be ruled out. Widespread
cloud cover will keep low temperatures extremely mild across central
NC, in the upper-60s to lower-70s.
&&
.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
As of 345 PM Tuesday...
In the mid/upper-levels, an anticyclone over FL today will drift
newd to about midway between Bermuda and the South Atlantic coast,
while a cyclone settles across the mid-South. Deep sswly flow
between the two will provide the steering for Tropical Cyclone
Helene into the eastern Gulf of Mexico and also convectively-
enhanced disturbances from the cntl Gulf coast through the wrn
Carolinas.
At the surface, the quasi-stationary front now over cntl NC will
retreat nwwd into srn and cntl VA on Wed, while an upstream cold
front now moving across the TN and lwr MS Valleys will slow and
stall invof the srn Appalachians and GA. Aside from a sea breeze,
the main foci for convergence and convection will consequently
become oriented just to the north and west of cntl NC and where the
otherwise weakly-forced warm sector will exist.
While isolated showers and storms will be possible with diurnal
heating/destabilization, as early morning stratus retreats nwwd and
lifts/scatters within the warm sector and/or along the sea breeze,
the axis of convection will likely materialize through the wrn
Carolinas and especially upslope into the mountains.
temperatures should be more-uniformly warmer and in the 80s on Wed,
with continued unseasonably mild/humid conditions and lows in the mid
60s to near 70 Wed night.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
As of 230 PM Tuesday...
The 11am track of Tropical Storm (eventually Hurricane) Helene calls
for a landfall along the Big Bend region of Florida Thursday
evening, moving up through northern Georgia Friday morning, and
becoming a post-tropical cyclone over Indiana by Saturday morning.
The cone for Helene remains to the west of our forecast area,
although the cone specifically forecasts the center of the storm.
Helene is expected to be a larger than typical storm and impacts
will be felt well outside of the cone.
The impacts from Helene should start making their way into the
forecast area Thursday, with the greatest rainfall intensity and
wind speeds occurring Thursday night and Friday. It`s too early to
look at specifics, but multiple inches of rain are likely across
western counties, with lesser amounts expected to the east. It also
appears that the wind and wind gusts will remain below tropical
storm strength of 40 mph, with the higher values remaining to the
west.
The forecast should begin to dry out by Friday night as the
circulation from Helene moves over the Midwest. However, as Helene
becomes post-tropical and develops warm/cold fronts, scattered
thunderstorms should remain in the forecast through early next week.
Normal late-September temperatures are around 80/60 degrees, and
Saturday is expected to be the warmest day with slightly above
normal highs. Lows will be above normal throughout the forecast.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 830 PM Tuesday...
Anomalous moisture embedded within swly flow will continue to
generate MVFR/IFR stratus along a stalled boundary over the northern
Piedmont. This will effectively keep KINT/KGSO and perhaps KRDU sub-
VFR through this evening. Then, all sites will sock back down to
IFR/LIFR later tonight through overnight period. The cloud deck
will slowly erode from south to north through Wednesday afternoon
(KINT/KGSO may very likely remain sub-VFR however through the end of
the 24 hour TAF period).
In addition to stratus restrictions, showers and storms
will likely move sw to ne through the overnight period. Some of
these storms will affect INT,GSO and RDU. KINT/KGSO and even KRDU.
Additional showers and storms may be possible Wednesday afternoon,
primarily near KINT/KGSO.
Outlook: Under a persistent anomalous moisture regime, late
night/early morning sub-VFR ceilings and visibilities will be
possible each day in the outlook period. Additional showers and
storms will also be possible each day. While there is still some
uncertainty wrt to the evolution of Tropical Storm Helene, it does
appear that heavy rain and perhaps gusty winds will be possible late
Thursday night through early Saturday morning (highest impacts as of
now would be likely at KINT/KGSO).
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 8 PM EDT this evening through Wednesday morning for
NCZ007>010-021>026-041.
&&
$$
SYNOPSIS...MWS/CBL
NEAR TERM...Danco
SHORT TERM...MWS
LONG TERM...Green
AVIATION...Badgett/Luchetti
Area Forecast Discussion
National Weather Service Tallahassee FL
1111 PM EDT Tue Sep 24 2024
...New UPDATE, MARINE...
.UPDATE...
Issued at 1110 PM EDT Tue Sep 24 2024
The 11 pm EDT advisory package from NHC effectively has little or
no change. The center of Helene is still forecast to make
landfall along the Big Bend coast as a Cat 3 late Thursday.
Mostly unrelated to Helene, Wednesday should be an active day of
thunderstorms and heavy rain, especially for the Panhandle and
southeast Alabama. A slow-moving or nearly stationary surface
boundary will set up over the Panhandle, serving as a focus for
thunderstorm development against the backdrop of moderate
instability, a moistening air mass, and about 25-30 knots of bulk
shear to help storms organize into clusters. Convection will start
to blossom along the Emerald Coast before sunrise on Wednesday.
&&
.SYNOPSIS...
Issued at 354 PM EDT Tue Sep 24 2024
Weather turns active on Wednesday as showers/thunderstorms
increase ahead of Tropical Storm Helene. Isolated severe weather
and heavy rain is possible with this activity.
Helene is forecast to approach Apalachee Bay as a likely major
hurricane on Thursday with conditions deteriorating from south to
north. Landfall is forecast somewhere along the NE Gulf Coast as a
major hurricane and bring a myriad of potentially significant
threats: life-threatening storm surge, tropical storm/hurricane-
force winds, flash flooding, and isolated tornadoes.
Conditions should improve heading into the weekend as Helene
exits the region.
&&
.NEAR TERM...
(Through Wednesday)
Issued at 354 PM EDT Tue Sep 24 2024
The benign weather we have been experiencing the past couple days
gives way to increasing rain chances tomorrow. A frontal boundary
attendant to a broad/energetic upper trough over the Central
Plains interacts with tropical moisture off the Gulf to be the
primary foci for showers/thunderstorms. The environment is
forecast to be somewhat conducive for loosely organized convection
capable of isolated gusty/damaging winds, locally heavy rain, and
perhaps a brief tornado or two. For these reasons, the SPC
introduced a Marginal Risk (level 1 of 5) of severe weather in the
Day 2 Outlook for SE AL, the FL Panhandle, and parts of the FL
Big Bend/SW GA.
The 18Z HRRR initiates convection off the Emerald Coast as a N-S-
oriented cluster in the morning before spreading inland with
time. Storm mode appears to take on linear-like banding shapes,
which could spell heavy rain/flooding trouble that`s not even
directly associated with TC Helene, yet. In response to this
evolution, the WPC maintains a Slight Risk (level 2 of 4) over
parts of the Emerald/Forgotten Coasts and Marginal Risk (level 1
of 4) elsewhere for the Day 2 Outlook. The former may drop
southward to the Wiregrass Region in subsequent outlooks.
With weather aiming to be active on Wednesday, users are highly
encouraged to finalize any outdoor preparedness plans ahead for
Helene sooner than later. Given the increased cloud cover/rain
chances, expect relatively cooler daytime temperatures with
widespread highs in the 80s. Overnight lows drop to the low 70s.
&&
.SHORT TERM...
(Wednesday night through Friday)
Issued at 354 PM EDT Tue Sep 24 2024
The focus will be the approaching Tropical Storm Helene, which is
expected to become a hurricane or major hurricane prior to
landfall somewhere along the Florida Panhandle or Big Bend.
There will be a developing upper level trough over the middle
Mississippi Valley that will pull in Tropical Storm Helene,
bringing it up north through the Gulf of Mexico. Tropical Storm
Helene is expected to strengthen to a hurricane bringing
significant impacts to the Florida Panhandle and Big Bend,
possibly extending further inland to SE Alabama and SW Georgia.
Winds will be gradually increasing through the day on Thursday
with scattered showers already occurring.
The 11AM EDT Advisory still indicates that Tropical Storm Helene
will make landfall along the Florida Big Bend as a Major Category
3 Hurricane sometime late Thursday evening.
The 12z ensemble runs do not show much shift east or west from
the 06z ensemble runs as to where the center may go. The object to
focus on is that this will be a very large storm in size. Impacts
will be felt well outside of the cone of uncertainty. Expect
conditions to begin deteriorating by midday Thursday. All
locations along the northern Gulf and along the eastern portions
of the Florida Big Bend and west coast of Florida are at risk
currently for a major hurricane bringing significant wind, storm
surge inundation, and rainfall. Additionally, Tropical Storm
Helene is likely to have a faster than usual storm motion as it
accelerates north around landfall and moves inland. When combined
with the storm`s large size and fast forward motion, significant
winds and gusts could extend further inland than folks are
typically accustomed to seeing during tropical systems.
Reminder, every storm is unique in its own way with what it
brings in regards to threats and hazards, and each system brings
uncertainty that can leave you unprepared if you`re not ready for
a *reasonable* worst case scenario. Don`t underestimate the danger
you could experience with Helene just because you avoided impacts
from previous storms.
With watches issued and upcoming warnings are likely, if you are
under a tropical/hurricane/surge watch or warning, be sure to
check the forecast at weather.gov (type your zip code to see
watches/warnings at your location) and read the tropical
watch/warning text. These watches/warnings will list out
conditions that you should be prepared for. These watches/warnings
also list out reasonable worst case scenarios you should be ready
for at your location.
&&
.LONG TERM...
(Friday Night through Monday)
Issued at 354 PM EDT Tue Sep 24 2024
Helene will be out of the region by the start of this long term
period. We can expect to return to typical conditions for late
September with highs in the mid-80s with overnight lows in the
upper 60s/low 70s. PoPs chances will be low during the weekend but
the upper level trough from before the hurricane will be moving
east/northeast across the eastern one-third of the U.S. pushing a
frontal boundary across the TAE CWA that may increase rain chances
to about 30% by the end of the long term.
&&
.AVIATION...
(00Z TAFS)
Issued at 805 PM EDT Tue Sep 24 2024
Flying conditions this evening are fairly tame, with mid-level
convective debris clouds decreasing and affecting some terminals.
Overnight, southerly flow aloft will increase somewhat, bringing
a more richly moist and moderately unstable air mass north off the
Gulf. This will interact with a surface boundary over the
Panhandle and southeast Alabama to bring a blossoming of
convection over ECP before sunrise, expanding north to DHN after
sunrise. TLH and ABY will be near the eastern edge of convection
through the morning.
On Wednesday afternoon, rain-cooled air near ECP and DHN may
bring a decrease in convection, but areas that did not previously
see thunder will see convection and perhaps thunder bubbling up in
the afternoon.
&&
.MARINE...
Issued at 1110 PM EDT Tue Sep 24 2024
At 11 pm EDT Tuesday, the center of Tropical Storm Helene was
located over the far northwest Caribbean Sea. Helene will move
northward across the eastern Gulf on Wednesday and Thursday,
rapidly strengthening to a major hurricane before making landfall
along the Big Bend Coast late Thursday. Helene will quickly move
inland on Friday, so conditions will improve over the waters.
Gentle to moderate southwest breezes will prevail this weekend, as
a large area of low pressure spins over the Lower Mississippi
Valley.
&&
.FIRE WEATHER...
Issued at 354 PM EDT Tue Sep 24 2024
Fire weather concerns are minimal over the next 3 days as rain
chances markedly increase from a frontal system moving into the MS
Valley, followed by the arrival of TC Helene late this week.
For Wednesday, showers and thunderstorms mainly focus west of the
Apalachicola River basin. Some may be strong to severe capable of
gusty/damaging winds, and locally heavy rain.
On Thursday, tropical moisture surging off the Gulf from the
approaching Helene is expected to bring squally weather with
conditions deteriorating ahead of landfall somewhere along the NE
Gulf coast as a likely major hurricane. Hurricane conditions are
possible across the FL Big Bend while tropical storm conditions
are possible for eastern portions of the FL Panhandle. Widespread
wetting rains are expected with potential for flash flooding
(locally considerable).
Very high dispersions are forecast on Friday thanks to breezy
gradient winds from Helene`s large circulation despite pulling
away from the region.
&&
.HYDROLOGY...
Issued at 354 PM EDT Tue Sep 24 2024
Primary focus continues to on the approach of Tropical Storm
Helene to the region. The system has the potential to bring
significant rain to the region, even accounting for its fast
forward motion as it nears the Florida Big Bend. Model guidance
has been in good agreement that a precursor event of heavy
rainfall will overspread the Florida Big Bend and Panhandle
Wednesday evening with the bulk of the rainfall arriving later on
Thursday. This will lead to some heavy rainfall totals across
North Florida and South Georgia totaling 5 to 10 inches of rain
with isolated maximum totals approaching 10 to 15 inches.
The entire forecast area is included in a Moderate risk for flash
flooding (level 3 out of 4) for Thursday. It is possible that
this risk level is increased in future outlooks. Nonetheless,
these amounts will lead to considerable urban flash flooding along
with the potential for moderate flooding, especially on the
Ochlockonee River Basin. Depending on where the heaviest rains are
distributed inland, it is entirely possible that other river
basins could experience moderate riverine flooding in the days
ahead.
For storm surge information, please refer to the latest
information from the National Hurricane Center. This is an
extremely dangerous storm surge threat in the Apalachee Bay. Storm
Surge around Apalachee Bay will not just merely be a coastal
event in this system, but will spread many miles inland. If
ordered to evacuate, heed the advice of local emergency managers -
it could save your life!
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 73 86 72 79 / 10 50 90 90
Panama City 75 85 72 79 / 30 80 90 90
Dothan 71 85 70 76 / 30 70 90 90
Albany 73 87 72 78 / 10 50 80 90
Valdosta 71 88 72 81 / 0 30 80 90
Cross City 73 90 73 85 / 0 60 90 90
Apalachicola 77 84 73 81 / 40 70 100 100
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...Flood Watch from Wednesday evening through Friday morning for
FLZ007>019-026>029-034-108-112-114-115-118-127-128-134.
Tropical Storm Warning for FLZ011>013-112.
Hurricane Warning for FLZ014>019-026>029-034-114-115-118-127-128-
134.
Storm Surge Warning for FLZ027-115-118-127-128-134.
High Rip Current Risk through late Friday night for FLZ114-115.
GA...Flood Watch from Wednesday evening through Friday morning for
GAZ120>131-142>148-155>161.
Tropical Storm Watch for GAZ120>131-142>144-155.
Hurricane Watch for GAZ145>148-156>161.
AL...Flood Watch from Wednesday evening through Friday morning for
ALZ065>069.
Tropical Storm Watch for ALZ067-069.
GM...Tropical Storm Warning for GMZ750-770.
Hurricane Warning for GMZ730-752-755-765-772-775.
&&
$$
NEAR TERM...IG3
SHORT TERM...Montgomery
LONG TERM....Montgomery
AVIATION...Haner
MARINE...Haner
FIRE WEATHER...IG3
HYDROLOGY...Godsey