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Tropical Hurricane Idalia
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- Start date
weatherguy
Member
Idalia New 12z Run HAFS 142 mph Cat 4:
Looks like that all hurricane models showing >110kts at landfall with the HMON strongest with pressure at ~930mb and the HAFS-B at surface wind of ~125kts.
Henry2326
Member
18z....
Henry2326
Member
4 pm UHC discussion..tops out at 100 mph...currently.
The intensity forecast is somewhat challenging. Idalia will be
traversing eastern Gulf of Mexico waters of high oceanic heat
content, and the environmental air mass should remain fairly moist.
The flow to the east of an upper-level trough could impart some
vertical wind shear over the system, but this shear could also be
compensated by the conducive effect of upper-level diffluence.
There is considerable spread in the model intensity guidance,
ranging from minimal to major hurricane status before landfall on
the northeast Gulf coast. The official intensity forecast is a
little higher than the previous one, and remains near the higher
end of the guidance. Given the uncertainties, users should monitor
future NHC forecasts for possible changes in the predicted strength
of Idalia, and prepare for possible significant impacts within the
hurricane and storm surge watch areas.
The intensity forecast is somewhat challenging. Idalia will be
traversing eastern Gulf of Mexico waters of high oceanic heat
content, and the environmental air mass should remain fairly moist.
The flow to the east of an upper-level trough could impart some
vertical wind shear over the system, but this shear could also be
compensated by the conducive effect of upper-level diffluence.
There is considerable spread in the model intensity guidance,
ranging from minimal to major hurricane status before landfall on
the northeast Gulf coast. The official intensity forecast is a
little higher than the previous one, and remains near the higher
end of the guidance. Given the uncertainties, users should monitor
future NHC forecasts for possible changes in the predicted strength
of Idalia, and prepare for possible significant impacts within the
hurricane and storm surge watch areas.
GoDuke
Member
Damn we gonna end up dry in CLT
HugeSnowStick
Member
I think this is way too far east. The upper level low in the NE Gulf is going to move out quickly, then allowing it to bend back to the WNW, Just IMO.
Area Forecast Discussion
National Weather Service Peachtree City GA
258 PM EDT Sun Aug 27 2023
...Afternoon Area Forecast Discussion...
.SHORT TERM...
(This afternoon through Monday)
Issued at 224 PM EDT Sun Aug 27 2023
Key Messages:
- Scattered thunderstorms will continue through this evening,
with isolated strong or severe downbursts possible.
- Widespread thunderstorm activity is anticipated Monday, with
locally heavy rainfall and isolated flooding possible in
northern Georgia.
At 3 PM, radar indicated scattered shower and thunderstorm
activity across the region. SBCAPE values were in the 2500 to 4000
j/kg range, via the SPC Mesoanalysis page. Couple this with DCAPE
values near 1000 j/kg from Atlanta southward to Columbus and
inverted V profiles below 800 mb (see 18Z sounding), and the
environment is supportive of localized down burst activity. Several
storms have already shown down burst signatures with potential
gusts near 40 mph. Expect this trend to continue into the
evening, with any stronger updrafts potentially producing severe
level winds and tree damage. Due to the nature of the
environment, any damaging winds should be very localized to the
area directly under the storms.
Tonight through Monday:
A weak mid level shortwave approaching from the west should
provide the lift to keep scattered shower and thunderstorm
activity going across northern Georgia through tonight. With the
loss of day time heating and subsequent drop in instability, this
activity should remain sub severe. Thus regular rainfall will be
the main concern overnight.
Diurnal heating and a lingering frontal boundary should combine
to produce widespread thunderstorm activity in northern and
central Georgia Monday afternoon. Precipitable water values
hovering near 2 inches and slow storm motions should favor higher
rainfall rates. It wouldn''t be surprising if rain rates with some
storms topped 2 inches per hour, especially in northern Georgia.
The Weather Prediction Center (WPC) has latched on to this
potential and issued a Slight Risk (level 2 of 4) for flooding in
northern Georgia. The Atlanta metro is included in the Slight Risk
area. A couple of storms could also produce strong or severe
downburst winds, but this threat is second to the flooding risk.
Areas from Macon southward to Columbus will be flirting with heat
index values near 105 degrees again Monday afternoon. Given the
potential for thunderstorms and the marginal nature of the heat
(Heat Advisory criteria is 105 degree) we decided to hold of on an
extension to the Heat Advisory at this time. The evening or
overnight shifts may reconsider the need for a Heat Advisory.
Albright
&&
.LONG TERM...
(Tuesday morning through next Saturday)
Issued at 224 PM EDT Sun Aug 27 2023
- Tuesday, a stalled frontal boundary will serve as the focus
for shower and thunderstorm activity.
- Tropical Storm Idalia is expected to bring heavy rainfall to
portions of central and eastern Georgia early Wednesday and
will lead to flooding concerns through Thursday. See below
discussion for more details.
- High pressure returns, moderating temperatures back to
seasonable values ranging from the 80s during the day and 60s
overnight.
Tuesday into Next Weekend:
Shower and thunderstorm activity will be widespread
Tuesday as the stalled frontal boundary remains draped over central
Georgia. While the threat for severe weather will be relatively low,
cannot rule out an isolated severe thunderstorm producing damaging
wind gusts. As tropical moisture surges northward ahead of Idalia,
PWATs exceeding 2.0" across central Georgia will result in localized
flooding concerns Tuesday. As is typical with tropical systems,
hydrologic concerns will persist through Thursday as now Tropical
Storm Idalia is expected to become a hurricane before making
landfall near the Big Bend region along the Florida Panhandle. For
this forecast cycle, the primary threat Idalia will impose to our
area is heavy rain where flooding concerns are expected to impact
our southeastern counties. Currently, 3 to 5.5" of rain are forecast
to fall, but locally higher amounts will be possible. As a result, a
Slight Risk for Excessive Rainfall has been diagnosed for central
and eastern Georgia. While confidence is growing that Georgia will
experience some degree of impacts from Idalia, our range and
coverage of threats may expand or diminish depending on the exact
track she takes. Global ensemble members continue to exhibit the
potential for Idalia to jog further west or further east thus
warranting a close monitor of the progression of the track through
the Gulf. If the track bumps westward, we could see an increasing
wind and tornado threat for portions of our forecast area. Please
stay tuned as the forecast evolves in the coming days. After Idalia
passes through, high pressure will build back in and bring
seasonable temperatures back to the forecast area. Generally, more
quiet weather will be expected though isolated diurnally driven
convection may be possible through the end of the period.
Long
Area Forecast Discussion
National Weather Service Peachtree City GA
258 PM EDT Sun Aug 27 2023
...Afternoon Area Forecast Discussion...
.SHORT TERM...
(This afternoon through Monday)
Issued at 224 PM EDT Sun Aug 27 2023
Key Messages:
- Scattered thunderstorms will continue through this evening,
with isolated strong or severe downbursts possible.
- Widespread thunderstorm activity is anticipated Monday, with
locally heavy rainfall and isolated flooding possible in
northern Georgia.
At 3 PM, radar indicated scattered shower and thunderstorm
activity across the region. SBCAPE values were in the 2500 to 4000
j/kg range, via the SPC Mesoanalysis page. Couple this with DCAPE
values near 1000 j/kg from Atlanta southward to Columbus and
inverted V profiles below 800 mb (see 18Z sounding), and the
environment is supportive of localized down burst activity. Several
storms have already shown down burst signatures with potential
gusts near 40 mph. Expect this trend to continue into the
evening, with any stronger updrafts potentially producing severe
level winds and tree damage. Due to the nature of the
environment, any damaging winds should be very localized to the
area directly under the storms.
Tonight through Monday:
A weak mid level shortwave approaching from the west should
provide the lift to keep scattered shower and thunderstorm
activity going across northern Georgia through tonight. With the
loss of day time heating and subsequent drop in instability, this
activity should remain sub severe. Thus regular rainfall will be
the main concern overnight.
Diurnal heating and a lingering frontal boundary should combine
to produce widespread thunderstorm activity in northern and
central Georgia Monday afternoon. Precipitable water values
hovering near 2 inches and slow storm motions should favor higher
rainfall rates. It wouldn''t be surprising if rain rates with some
storms topped 2 inches per hour, especially in northern Georgia.
The Weather Prediction Center (WPC) has latched on to this
potential and issued a Slight Risk (level 2 of 4) for flooding in
northern Georgia. The Atlanta metro is included in the Slight Risk
area. A couple of storms could also produce strong or severe
downburst winds, but this threat is second to the flooding risk.
Areas from Macon southward to Columbus will be flirting with heat
index values near 105 degrees again Monday afternoon. Given the
potential for thunderstorms and the marginal nature of the heat
(Heat Advisory criteria is 105 degree) we decided to hold of on an
extension to the Heat Advisory at this time. The evening or
overnight shifts may reconsider the need for a Heat Advisory.
Albright
&&
.LONG TERM...
(Tuesday morning through next Saturday)
Issued at 224 PM EDT Sun Aug 27 2023
- Tuesday, a stalled frontal boundary will serve as the focus
for shower and thunderstorm activity.
- Tropical Storm Idalia is expected to bring heavy rainfall to
portions of central and eastern Georgia early Wednesday and
will lead to flooding concerns through Thursday. See below
discussion for more details.
- High pressure returns, moderating temperatures back to
seasonable values ranging from the 80s during the day and 60s
overnight.
Tuesday into Next Weekend:
Shower and thunderstorm activity will be widespread
Tuesday as the stalled frontal boundary remains draped over central
Georgia. While the threat for severe weather will be relatively low,
cannot rule out an isolated severe thunderstorm producing damaging
wind gusts. As tropical moisture surges northward ahead of Idalia,
PWATs exceeding 2.0" across central Georgia will result in localized
flooding concerns Tuesday. As is typical with tropical systems,
hydrologic concerns will persist through Thursday as now Tropical
Storm Idalia is expected to become a hurricane before making
landfall near the Big Bend region along the Florida Panhandle. For
this forecast cycle, the primary threat Idalia will impose to our
area is heavy rain where flooding concerns are expected to impact
our southeastern counties. Currently, 3 to 5.5" of rain are forecast
to fall, but locally higher amounts will be possible. As a result, a
Slight Risk for Excessive Rainfall has been diagnosed for central
and eastern Georgia. While confidence is growing that Georgia will
experience some degree of impacts from Idalia, our range and
coverage of threats may expand or diminish depending on the exact
track she takes. Global ensemble members continue to exhibit the
potential for Idalia to jog further west or further east thus
warranting a close monitor of the progression of the track through
the Gulf. If the track bumps westward, we could see an increasing
wind and tornado threat for portions of our forecast area. Please
stay tuned as the forecast evolves in the coming days. After Idalia
passes through, high pressure will build back in and bring
seasonable temperatures back to the forecast area. Generally, more
quiet weather will be expected though isolated diurnally driven
convection may be possible through the end of the period.
Long
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This was the ICON last Wedneday 12z @ 00z 8/30
96 hours later, today's 12z, pretty solid model if it comes to be.
96 hours later, today's 12z, pretty solid model if it comes to be.
Henry2326
Member
18z GFS getting with the program at 958.
Brent
Member
Big oof on the GFS 
Shaggy
Member
Gfs has it going from landfall to cape fear in 18 hours. This should reduce flooding with exception to that band of heavy rain in the northern half of the storm on the gfs.
Gonna be looking at another high end Cat 4/Cat 5 landfall.
HurricaneFred
Member
BHS1975
Member
Lol… I figured it would have gone down to at least 890 on the first run
There is new convention building around the LLC.
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For those who want this on a panhandle to GA to WNC route, it is going to have to get moving quickly...(IMO that route is trending less and less, mainly because of the reform East/movement more over the water vs the Yuc). I think this is a Tampa to Orlando to JAX to ILM route.