Possible Development Near the GA/Bahamas (Is Invest 98L)

[Blown Away]

2 PM TWO:

Southwestern Atlantic:
A large non-tropical low pressure system is expected to develop this
weekend across the northeastern Caribbean sea and southwestern
Atlantic. The system is expected to initially be very broad and
disorganized, but environmental conditions could support gradual
subtropical or tropical development beginning early next week while
it moves generally northwestward or westward over the southwestern
Atlantic.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...30 percent.

No convection in the lemon area yet...

[wxman57]

Definitely looks non-tropical. Wind shear from the Caribbean to the SE U.S. will be about 50-70 kts. Models are developing a very big, broad low with strongest winds about 500 miles to the north along the coast from the Outer Banks to NE Florida. Euro has winds offshore 30-45 kts there Tuesday night, but no penetration inland. Winds are due to an increased pressure gradient between the low and strong high pressure over the eastern U.S. Air over the SE U.S. will be cool and dry, certainly not tropical. By the way, you can see what the models are developing on that satellite loop above this post. Look at 30N/82W. See that rotation? It marks an upper-level low that the models develop at the surface by late this weekend.

[ronjon]

18z GFS shows 1005 low pressure moving across south Florida into the GOM where it meanders thru Saturday in the eastern Gulf then gets shoved south and eventually west into the SW GOM. This looks like a big wet sloppy system.

[cycloneye]

8 PM TWO.

2. Southwestern Atlantic:
A large non-tropical low pressure system is expected to develop this
weekend across the northeastern Caribbean Sea and southwestern
Atlantic. The system is expected to initially be very broad and
disorganized, but environmental conditions could support gradual
subtropical or tropical development beginning early next week while
it moves generally northwestward or westward over the southwestern
Atlantic.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...30 percent.

[Jr0d]

18z GFS shows 1005 low pressure moving across south Florida into the GOM where it meanders thru Saturday in the eastern Gulf then gets shoved south and eventually west into the SW GOM. This looks like a big wet sloppy system.

Im going to call the current GFS run a "happy hour" one. The CMC looks more reasonable.

It is concerning that it is possible for a low to form or sit near the Gulf Stream, Florida Keys and even as far west as the loop current. Water temperatures are plenty warm to support a hurricane...shear should prevent this and I would probably bet on it however we have seen hurricanes form in cooler than expected water water temperatures if the temperature gradient is right.

These late season hybrid systems are tricky.

[LarryWx]

A TC is back on the UKMET at 0Z with a TS (strongest run yet) moving WNW toward central FL as of 144 (keep in mind the strong gradient between this and the big NE high):

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 102 HOURS
FORECAST POSITION AT T+102 : 24.5N 71.7W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 08.11.2022 108 25.3N 71.4W 1008 25
0000UTC 09.11.2022 120 26.2N 72.4W 1006 35
1200UTC 09.11.2022 132 26.4N 75.9W 1007 36
0000UTC 10.11.2022 144 26.9N 78.6W 1006 40

[BobHarlem]

The 0z gfs (So far out to 168 hours or so is a lot more organized/concentrated with this system than earlier runs over the Bahamas (goes right over Nassau) and makes a run for strengthening toward south Florida (994mb) then over Tampa, most of the energy on the right side to the north.

[LarryWx]

It looks like the 0Z Euro sort of has two separate entities (check out the 850 vorticity). This is rather complex.

[Blown Away]

06z GEFS... A few strong TS close to Cat 1 pressures.

[Iceresistance]

2. Southwestern Atlantic:
A large non-tropical low pressure system is expected to develop
across the northeastern Caribbean Sea and southwestern Atlantic
during the next day or two. The system is initially expected be very
broad and disorganized, but it could begin to acquire subtropical or
tropical characteristics by the end of the weekend. Environmental
conditions could support additional gradual development early next
week and a subtropical or tropical depression could form while the
disturbance moves generally northwestward or westward over the
southwestern Atlantic.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...40 percent.

[cane5]

Can someone explain how deep the low pressure gradient might get relative to what we can expect in winds and when that might happen over South Florida next week and for how long since the system will be moving slowly ?

[Steve H.]

NWS Melbourne: On Sunday, mid level ridging over the Gulf of Mexico is expected to
break down. As this occurs, the broad center of low pressure over
the southeastern Bahamas will begin to drift northwestward.
Meanwhile, a narrow inverted trough starts to take shape, stretching
from the western Atlantic into the Gulf. Slight chance PoPs are
forecast to continue on Sunday with some activity drifting inland to
I-95. Beach and sea conditions will become more hazardous with a
high rip current risk and unfavorable small craft conditions
expected.

Operational guidance paints a less clear picture of the Atlantic low
pressure system and its evolution next week. This includes whether
or not it will take on some tropical characteristics or remain
subtropical in nature. Thus, NHC maintains a 30 percent chance of
cyclone formation in the next five days. Regardless of the
particulars, ensemble guidance suggests this system is going to
influence our weather through at least the first half of the work
week. Rain chances go up Monday afternoon and night as mid level
energy works to steer more moisture in the direction of east central
Florida. Northeasterly surface winds will increase in response to a
tightening pressure gradient, resulting in a further building of
seas Monday night into Tuesday. Forecast soundings Tuesday into
Tuesday night latch on to PW values of 2 inches or greater. With
greater atmospheric support in the mid levels Tuesday into early
Wednesday, PoPs markedly increase to 60 and 70 percent near the
coast and 40 to 50 percent inland. Even a few thunderstorms are
possible over coastal locations Tuesday afternoon and night. Total
QPF may reach 1 to 3 inches along and east of I-95 with locally
higher amounts.

Wednesday-Friday...Variability in model guidance from Wednesday
onward precludes more detailed expectations. However, the forecast
does highlight a likely continuation of long-duration coastal and
marine hazards. Seas will remain dangerous to small craft through at
least Thursday, even as east-northeasterly winds relax a bit. The
potential for coastal erosion and life threatening rip currents will
remain so long as the aforementioned low pressure region remains
east of the Florida Peninsula. The 00Z GFS even appears to
reorganize a smaller vort max Thursday afternoon and takes it across
the Peninsula Friday morning. In contrast, the ECMWF does not
develop a similar feature, but instead maintains a weaker, broader
center of low pressure in the central Gulf --- before eroding the
feature completely and phasing it in with an advancing trough over
the east-central CONUS.

This forecast reflects a slowly decreasing trend in PoPs Thursday
and Friday for now, though that is subject to a change in model
solutions. Winds will veer to a southerly direction late week and
slacken, allowing seas to decrease.

&&

[cane5]

NWS Melbourne: On Sunday, mid level ridging over the Gulf of Mexico is expected to
break down. As this occurs, the broad center of low pressure over
the southeastern Bahamas will begin to drift northwestward.
Meanwhile, a narrow inverted trough starts to take shape, stretching
from the western Atlantic into the Gulf. Slight chance PoPs are
forecast to continue on Sunday with some activity drifting inland to
I-95. Beach and sea conditions will become more hazardous with a
high rip current risk and unfavorable small craft conditions
expected.

Operational guidance paints a less clear picture of the Atlantic low
pressure system and its evolution next week. This includes whether
or not it will take on some tropical characteristics or remain
subtropical in nature. Thus, NHC maintains a 30 percent chance of
cyclone formation in the next five days. Regardless of the
particulars, ensemble guidance suggests this system is going to
influence our weather through at least the first half of the work
week. Rain chances go up Monday afternoon and night as mid level
energy works to steer more moisture in the direction of east central
Florida. Northeasterly surface winds will increase in response to a
tightening pressure gradient, resulting in a further building of
seas Monday night into Tuesday. Forecast soundings Tuesday into
Tuesday night latch on to PW values of 2 inches or greater. With
greater atmospheric support in the mid levels Tuesday into early
Wednesday, PoPs markedly increase to 60 and 70 percent near the
coast and 40 to 50 percent inland. Even a few thunderstorms are
possible over coastal locations Tuesday afternoon and night. Total
QPF may reach 1 to 3 inches along and east of I-95 with locally
higher amounts.

Wednesday-Friday...Variability in model guidance from Wednesday
onward precludes more detailed expectations. However, the forecast
does highlight a likely continuation of long-duration coastal and
marine hazards. Seas will remain dangerous to small craft through at
least Thursday, even as east-northeasterly winds relax a bit. The
potential for coastal erosion and life threatening rip currents will
remain so long as the aforementioned low pressure region remains
east of the Florida Peninsula. The 00Z GFS even appears to
reorganize a smaller vort max Thursday afternoon and takes it across
the Peninsula Friday morning. In contrast, the ECMWF does not
develop a similar feature, but instead maintains a weaker, broader
center of low pressure in the central Gulf --- before eroding the
feature completely and phasing it in with an advancing trough over
the east-central CONUS.

This forecast reflects a slowly decreasing trend in PoPs Thursday
and Friday for now, though that is subject to a change in model
solutions. Winds will veer to a southerly direction late week and
slacken, allowing seas to decrease.

&&

Nice report….thanks

[wxman57]

Can someone explain how deep the low pressure gradient might get relative to what we can expect in winds and when that might happen over South Florida next week and for how long since the system will be moving slowly ?

First of all, I would not believe the GFS runs. Euro looks more realistic. What that means for south Florida is a non-event. Maybe some north wind 15-20 mph and less than 1/2 inch of rain. I think that winds of 35-45 mph will develop over the offshore waters along the coast from Jacksonville, FL to the Outer Banks. This will happen regardless of whether or not the NHC names the low. The wind will be produced by the gradient between this low (maybe 1008mb) and a 1040mb+ high over SE Canada.

I think that the NHC will up there "development" (really, naming) chances to 80-90% over the weekend. Whether the low is named or not, the impacts will be the same. Plenty of wind shear and cool, dry air flowing off the SE U.S. coast will prevent any significant strengthening of this non-tropical low. Wind will not penetrate much inland from the beaches. Most rain will be offshore. Wind slowly decreasing on Wednesday as the low weakens.

[cane5]

Can someone explain how deep the low pressure gradient might get relative to what we can expect in winds and when that might happen over South Florida next week and for how long since the system will be moving slowly ?

First of all, I would not believe the GFS runs. Euro looks more realistic. What that means for south Florida is a non-event. Maybe some north wind 15-20 mph and less than 1/2 inch of rain. I think that winds of 35-45 mph will develop over the offshore waters along the coast from Jacksonville, FL to the Outer Banks. This will happen regardless of whether or not the NHC names the low. I think that the NHC will up there "development" (really, naming) chances to 80-90% over the weekend. Whether the low is named or not, the impacts will be the same. Plenty of wind shear and cool, dry air flowing off the SE U.S. coast will prevent any significant strengthening of this non-tropical low. Wind will not penetrate much inland from the beaches. Most rain will be offshore. Wind slowly decreasing on Wednesday as the low weakens.

Thanks waxman

[LarryWx]

From Jacksonville, FL, NWS: this is mainly gradient related between a low trough off the SE coast and and a very strong high to the north as opposed to a compact very strong low:

LONG TERM

(MONDAY NIGHT THROUGH THURSDAY)
ISSUED AT 350 AM EDT FRI NOV 4 2022

STRONG HIGH PRESSURE WILL BUILD TO THE NORTH EARLY THIS PERIOD,
WHILE AN INVERTED TROUGH STRENGTHENS OVER THE WESTERN ATLANTIC. THIS
PATTERN WILL THEN PERSIST THROUGH THIS PERIOD. THIS WILL LEAD TO A
PROLONGED PERIOD OF ENHANCED ONSHORE FLOW. CHANCES WILL EXIST EACH
DAY FOR PRECIPITATION TO COME ASHORE. A MYRIAD OF COASTAL HAZARDS
ARE POSSIBLE THIS PERIOD, INCLUDING GUSTY COASTAL WINDS, BEACH
EROSION, RIP CURRENTS, HIGH SURF, AND COASTAL FLOODING.

MARINE

ISSUED AT 350 AM EDT FRI NOV 4 2022

HIGH PRESSURE WILL SLOWLY MOVE AWAY TO THE NORTHEAST THROUGH THE
WEEKEND. AN INVERTED TROUGH OVER THE AREA THIS MORNING WILL FLATTEN
THROUGH TONIGHT. ANOTHER TROUGH WILL DEVELOP OVER THE WESTERN
ATLANTIC EARLY NEXT WEEK, AS HIGH PRESSURE BUILDS TO THE NORTHWEST
THEN NORTH. THIS PATTERN WILL LEAD TO A PROLONGED PERIOD OF ONSHORE
FLOW, WITH THE GRADIENT BETWEEN THE HIGHS AND TROUGHS LEADING TO
ELEVATED CONDITIONS.

INITIATING ADVISORIES WITH THIS ISSUANCE. FOR THE OUTER WATERS,
ADVISORY LEVEL CONDITIONS WILL BE EXPECTED FROM LATE TONIGHT THROUGH
MUCH OF NEXT WEEK, WITH A PERIOD OF GALES POSSIBLE AROUND MID WEEK.
WILL LIKELY NEED AN ADVISORY FOR INNER WATERS BY SUNDAY, WHICH WILL
THEN ALSO LAST THROUGH MUCH OF NEXT WEEK.

[LarryWx]

From NWS Charleston, SC: gales and major coastal flooding possible Mon-Wed for SC/GA and this may occur even if there is no actual STC or TC:

SATURDAY THROUGH WEDNESDAY: MARINE CONDITIONS SHOULD IMPROVE
SLIGHTLY BY SATURDAY EVENING THROUGH THE REMAINDER OF THE WEEKEND.
SOUTHEAST WINDS BECOMING MORE EAST NORTHEAST ON SUNDAY WILL AVERAGE
10-15 KT. A MORE SIGNIFICANT MARINE HAZARD EVENT IS EXPECTED MONDAY
THROUGH MUCH OF NEXT WEEK. A POWERFUL LOW PRESSURE SYSTEM MOVING
WEST FROM NEAR THE BAHAMAS WILL INTERACT WITH STRENGTHENING HIGH
PRESSURE TO THE NORTH, PRODUCING A STRONG NORTHEAST GRADIENT OVER
THE LOCAL WATERS FOR MUCH OF NEXT WEEK. GALE CONDITIONS WILL BE
POSSIBLE TUESDAY THROUGH WEDNESDAY FOR A MAJORITY OF THE MARINE
ZONES. SEAS ARE EXPECTED TO BUILD SUBSTANTIALLY NEXT WEEK WITH
VALUES 15+ FT OVER THE OUTER GA WATERS TUESDAY NIGHT INTO
WEDNESDAY.



TIDES/COASTAL FLOODING

ASTRONOMICAL TIDE LEVELS ARE RISING AS FULL MOON ON NOVEMBER
8TH APPROACHES. ADDITIONALLY, PERSISTENT MODERATE TO STRONG
NORTHEAST WINDS WILL CAUSE TIDAL ANAMOLIES TO INCREASE. BY EARLY
NEXT WEEK AN EVEN STRONGER NORTHEAST FLOW COULD PRODUCE
SUBSTANTIAL ANOMALIES THAT MAY RESULT IN MODERATE TO MAJOR
COASTAL FLOODING AT THE CHARLESTON HARBOR TIDE GAUGE.

COASTAL FLOODING COULD BEGIN TODAY ALONG COASTAL CHARLESTON AND
COLLETON COUNTIES AND AS EARLY AS SATURDAY EVENING FOR THE FAR
SOUTHERN SOUTH CAROLINA AND MUCH OF THE GEORGIA COAST. THE MORE
SIGNIFICANT TIDE LEVELS COULD BEGIN AS EARLY AS MONDAY EVENING
AND CONTINUE THROUGH WEDNESDAY OR THURSDAY. A SERIES OF COASTAL
FLOOD ADVISORIES AND POSSIBLY COASTAL FLOOD WATCHES/WARNINGS MAY
WILL BE NEEDED.

[MetroMike]

NHC has this area at 40% as of 8am.

[cycloneye]

11/4/22 12z GFS is the most bullish run so far.

[Blown Away]

12z GFS very bullish… Cat 2 into SFL in 5-6 days…