ATL: FRANCINE - Models

[Steve]

12z Mesoscales are out:

NAM 12km - Landfall @ 980mb +/- 5pm tomorrow St. Mary Parish (or so)
NAM 3km - Landfall @ 966mb +/- 6pm tomorrow St. Mary Parish (or so)
FV3 Hi-res - Landfall @ 975mb +/- 3pm tomorrow St. Mary Parish (or so)

Early Cycle 12z


Late Cycle 06z

[duris]

No thanks from New Orleans
 https://x.com/robperillo/status/1833520111577145428

[Steve]

ICON +/- 983mb St. Mary Parish 4/5pm tomorrow

https://www.tropicaltidbits.com/analysi ... 1012&fh=33

[tolakram]

ICON also shows marked weakening before landfall. Let's see just how good it is.

[ElectricStorm]

12z HWRF still running but so far the other three all have at least a Cat 2. HAFS-A strengthens all the way to Cat 3 at landfall which I think is pretty unlikely. The HMON looks similar to what I think will happen with around a 90kt peak followed by a 75-80kt landfall. Shear and dry air will be increasing closer to landfall so I'd assume this will be weakening at landfall rather than strengthening like other storms this year. Dry air could lead to more discrete supercells however, increasing the tornado threat.

Edit: And HWRF doing HWRF things and has 106kts before landfall.

[Steve]

ICON also shows marked weakening before landfall. Let's see just how good it is.

https://i.imgur.com/HPslldz.gif

Dy-no-mat?

[Steve]

Early Cycle 18z. Looking like Houma, Baton Rouge, etc. will be in the path.



Late Cycle EPS

[Stormlover70]

TABS ìs interesting

[Hammy]

TABS ìs interesting

Wondering if that particular model has a stronger system and pulls it further east due to the upper level flow

[AJC3]

TABS ìs interesting

Wondering if that particular model has a stronger system and pulls it further east due to the upper level flow

Quite the opposite. All the TAB (Trajectory And Beta) models are simple guidance based off GFS steering layer winds. The S in TABS stands for Shallow, so it would assume a weaker storm than the TABM(edium) and TABD(eep). And TAB guidance isn't very accurate or much used. I always called the BAM and TAB guidance the "poor man's shear model", because when shear increases, so does the spread in the 3 TAB models, as is the case with Francine.

[ronjon]

Latest NHC track is on the left side of guidance. New Orleans could be in the eastern eyewall if GFS and hurricane models verify.

[Steve]

Mesos NAMs 32/12/3 and FV3 all pretty much hit around New Orleans area. We’re talking less than 24 hours else this could go way farther east. Big lean to the NE but it’s above 26 now. Still wouldn’t be surprised for the coastal counties and next ones up in Mississippi and Alabama to get some TS conditions. I’ll also be looking for the hurricane models later to see how the bands come up. 18z’s all looked bad for tornados with big cells within feeders

[LARanger]

It seems to me most 18Z runs (GFS, the various H's, Euro) had this thing trying to go fishing in Lake Maurepas or Pontchartrain. I'll be very interested to see the 00Z runs.

[Steve]

It seems to me most 18Z runs (GFS, the various H's, Euro) had this thing trying to go fishing in Lake Maurepas or Pontchartrain. I'll be very interested to see the 00Z runs.

Not much on the south side but some north east and south eyewalls will do some damage whoever gets it.

[LARanger]

Looks like it didn't hold . . . the NHC 10p certainly put no stock in it, and some graphics marked 00Z (from Tropical Tidbits) suggest the ones I was looking at may have shifted back to where they were.

Edit: Then again, ICON is still going fishing in Maurepas, so (using the I-12 corridor as landmarks) that's aiming for Hammond moreso than Baton Rouge (or Denham Springs just east thereof).

Awaiting GFS 00Z.

Edit Edit: GFS 00Z skirts Lake Maurepas, per Pivotal.

[sasha_B]

Three of the four high-res hurricane models (HMON, HAFS-A and HAFS-B) show Francine peaking at at least Category 3 (HAFS-B actually shows a brief minimal Cat 4 - 116kt/963hPa at +15 hours). Most of them also show very substantial weakening in the 6 or so hours between 'peak intensity' and 'landfall', though, so a forecast intensity at landfall of around Category 2 seems reasonable. It's anything but a downward trend, regardless. (HWRF is still loading, but it looks like a peak at Cat 2 similar to the last run.)

[LARanger]

I dunno, y'all . . . I don’t wanna 'missmecast', but there seems to be a preponderance of Ponchartrain/NOLA in the 18Z and 00Z. The NHC 10p suggested little change and that the models were in good agreement, so obviously I'm missing something, but of all the ones I am seeing (Pivotal's list), it seems GFS is the west outlier, and even that's to the east of the NHC track by a smidgen.

Another case in point:

 https://x.com/WeatherProf/status/1833693014331380127

[LARanger]

Very little change for the 4am update. Indeed, they spoke of consensus guidance being in good agreement. I find this a bit baffling.

[Steve]

Rainfall estimates are in for the 12z mesoscales

FV3 has a foot or more of rain on the Northshore.
https://www.tropicaltidbits.com/analysi ... 1112&fh=54

NAM 3km has a foot swath up the bayou and river parishes.
https://www.tropicaltidbits.com/analysi ... 1112&fh=55

NAM 12km has the heaviest rain offshore and in south Terrebonne
https://www.tropicaltidbits.com/analysi ... 1112&fh=57

HRRR had a foot just west of New Orleans and across Lake Pontchartrain into Lacombe.
https://www.tropicaltidbits.com/analysi ... 1112&fh=19

[ColdMiser123]

The HWRF was too strong st 15z (11 am EDT), but I would still expect it to get the overall structure reasonably correct. Nothing has been sampled recently in the eastern eyewall, where the strongest winds may be.