Florence Day Three

9-7  Afternoon
Nothing really different.  NHC extended where it will cross 30n past 70W now.  Shear remains an obstacle for another 24-48 hrs.  There is nothing impeding it between that point and the coast.  We're still 6 days out, but a coastal hit seems 80% likely.  Area of concern remains the Carolinas.  But GA/NFL are remarkably still  in this, as is VA, NJ and Cape Cod.  After that perhaps Nova Scotia or Newfoundland. 

9-7 morning

Florence is beat down to a TS due to shear and a little dry air.  This was expected and accounted for.
Today we'll focus on tracks.

First, I'll compare the first time the NHC forecast the storm to pass 30N vs. their current forecast.

Three days ago, the forecast was to reach 30N at 56W.  Now its 70W.  That's 725 miles difference.

Tracks from the deterministic models.

Most alarming is that the NAVGEM went from Bermuda to EC landfall.  This makes all operational models hitting or nearing the coast.
6z Run of GFS

Florence day two

9/6 Evening.  Euro, Ukie and now the GFS have landfalls on the 12z runs.  JMA came to the party going west of 70 as well. NAVGEM is the only one left east of 70 and it hits Bermuda.
The 12z Gfs run is horrifying.

 Euro is slightly better. Weaker, less winds. 

9/6   Morning -  New day, new info, no real changes.    NHC last night boldly said that the trough would miss connecting with Florence, which would result in her heading west towards the EC.  How much of an influence the trough and Gordon (2) have remains to be seen as it could steer Florence more NW than WNW and bring her to Cuba.  Once the trough passes, high pressure and a ridge build (1) over and to the east of Florence, sending her west again.

Also watching steering currents, the anticyclone/ridge (3) in the Atlantic and eventually the storm hitting the PAC NW (4)

0z model summary:

• UKIE - remains furthest south.  Not sure why.  Likely hits SC
• CMC - middle south - hits NC near SC border
• Euro - in the middle.  Hits NC up to NJ.
• GFS - middle north.  Misses coast on a recurve, but comes really close to MD to MA
• NAVGEM - east of Bermuda, much slower
• JMA  - having problems with getting it.  The one run I saw is like the navgem
• Icon NC to NYC

0z Ukie

0z CMC path

0z cmc landfall winds

0z Euro landfall winds

0z Euro path

6z GFS closest

0z Icon

Look at the NHC models.

Lastly, ensembles are a little more optimistic on it missing.

0z euro ensembles

Hurricane Florence day one

9-5  Beginning coverage on Florence as model consensus has it missing a trough in the Atlantic and approaching the east coast.

First, where have we been...

Here's the trend from the last 8 runs of the GFS.  Until yesterday's late run, it kept it well at sea.

This was the initial forecast

Potential Tropical Cyclone Six Discussion Number   1
NWS National Hurricane Center Miami FL       AL062018
1100 AM AST Thu Aug 30 2018

The area of low pressure that moved off the coast of Africa has
continued to become better organized, and is producing a large
area of disturbed weather with gusty winds, but currently lacks a
well-defined center.  Environmental conditions are favorable for
additional development, and a tropical depression or a tropical
storm could form an any time today or Friday.  Given the high
chances that this system could bring tropical storm conditions to a
portion of the southern Cabo Verde Islands, advisories have been
initiated on Potential Tropical Cyclone Six.  Most of the intensity
guidance calls for strengthening and so does the NHC forecast.

The system is embedded within the easterly trades and this flow
pattern will steer the disturbance toward the west or west-
northwest during the next few days.  By the end of the forecast
period, a turn toward the northwest should begin as the system
reaches a weakness in the subtropical high.  This is consistent with
the output of the global models.

FORECAST POSITIONS AND MAX WINDS

INIT  30/1500Z 12.9N  18.4W   25 KT  30 MPH...POTENTIAL TROP CYCLONE
 12H  31/0000Z 13.2N  20.1W   30 KT  35 MPH...TROPICAL DEPRESSION
 24H  31/1200Z 13.5N  22.0W   35 KT  40 MPH
 36H  01/0000Z 14.0N  24.0W   45 KT  50 MPH
 48H  01/1200Z 15.0N  27.0W   55 KT  65 MPH
 72H  02/1200Z 16.5N  33.0W   65 KT  75 MPH
 96H  03/1200Z 18.5N  38.0W   65 KT  75 MPH
120H  04/1200Z 20.0N  42.0W   65 KT  75 MPH

TD Six was hatched on the 31st on the 21z advisory

That Forecast discussion maxed it out a 70mph.

TS Florence was named in the 5 am advisory on the 1st.  

Still the 5am forecast disco kept it at under Hurricane strength through day 4

For all of Sept 3rd she remained at 65-70mph speed until the 11am advisory on the 4th when she became a hurricane. 

Hurricane Florence Advisory Number  21
NWS National Hurricane Center Miami FL       AL062018
1100 AM AST Tue Sep 04 2018

...FLORENCE BECOMES THE THIRD HURRICANE OF THE ATLANTIC SEASON...
...NO THREAT TO LAND THROUGH THE WEEKEND...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...19.7N 42.5W
ABOUT 1240 MI...2000 KM WNW OF THE CABO VERDE ISLANDS
ABOUT 1270 MI...2045 KM ENE OF THE LESSER ANTILLES
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...990 MB...29.24 INCHES

11am ast disco mentions that the shear would knock her back to TS and then gain to H by 9th.   The track was uncertain though it clearly looked to be headed east of Bermuda and highly unlikely to make a US landfall.

This analysis didn't work out.  by 2pmAST she was 85mph.  By 11pm advisory she was 100mph.  And at 8:30 AST they advised she was Cat 3, 120mph at 961mb.  Intermediate advisory

So that takes us to the 11am Disco which adjusts the track west, but is highly uncertain, and not as far west as the models.  The analysis shows that a pocket of low shear allowed her to develop, but that the shear should increase and knock her down again.   

FORECAST POSITIONS AND MAX WINDS

INIT  05/1500Z 22.0N  45.7W  110 KT 125 MPH
 12H  06/0000Z 22.7N  47.2W  110 KT 125 MPH
 24H  06/1200Z 23.8N  49.0W  100 KT 115 MPH
 36H  07/0000Z 24.7N  50.6W   95 KT 110 MPH
 48H  07/1200Z 25.1N  52.1W   90 KT 105 MPH
 72H  08/1200Z 25.7N  54.7W   90 KT 105 MPH
 96H  09/1200Z 27.0N  57.0W   95 KT 110 MPH
120H  10/1200Z 28.5N  59.0W   95 KT 110 MPH

The GFS was really the last hold out as even the NHC ensembles are further west. 
6z NHC
12z nhc

The ukmet and euro ensembles have been onto this a few days earlier

9-3 0z euro ens

9-3 0z ukmet ens

Thoughts on the ridge/trough and other features that would affect this are at wxdisco

Hurricane Chris

7-12  Afternoon:  Landfall has either occurred or is imminent near St. Pierre.

Morning: Chris back to TS with 70mph winds.  Heaviest precip has transferred to the northwest portion of the storm, with winds on the northeast, which is typical for storms north of 40N.  As it converts to post tropical/extra tropical, winds will expand.  Newfoundland looks to be be taking a strong hit.  Even if the eye doesn't pass over land (which it looks like it will to me) the bulk of the damage is caused ahead of the eye and the precip will be to the NW putting the island in the direct path.

7-11  Chris made it to cat 2, with max sustained winds of 105mph overnight.  Lowest pressure was 970mb.  Chris is speeding away this evening with a chance that it hits Newfoundland tomorrow evening as a TS.  Still looks strong on the satellite this evening and is currently at 90mph winds moving northeast at 25mph.  Wind field should expand as it transitions to extra tropical.

7-10  
Latest Dropsonde with surface reading at 83mph

Afternoon -waiting for upgrade.  HDOB with 984mb low and 84mph winds.  Dropsonde with near surface winds of over 95mph.

Satelite

Morning update - still a TS with winds of 70mph.  The dry air is almost mixed out on the WV loop and the radar, while at a distance, briefly showed a complete eyewall.  Would need recon to provide a radar image to confirm.

Still predicted to be a cat one at max 90 mph and no threat to land until Newfoundland (but there is time for that to change).  Wouldn't be surprised if this reached 100 mph briefly either.   Would be surprised if it went higher, or didn't exceed 75 mph.

7-9  Will the eye reform?

Evening satellite prior to nightfall.

 Chris was named in the 5am advisory yesterday.  Its expected to hang around awhile, then head northeast.  Some advisories have gotten he max winds up to 90mph 11 pm disco but the opportunity to advance is limited by the upwelling going on underneath as it stays stationary.  If it can get into warmer water, then the structure would allow it to strengthen, possibly rapidly and get to 90mph.  However, NHC has tuned it down a notch since last night.   It is coming into radar though.

A look at the satellite

7-7  This hasn't made it to official TS status yet, but recon did show smfr winds at 50mph.

Here's how it looks mid day.  Its not going anywhere for now as its stalled under  a front.  Guidance and sense says that it should stay fairly close to where it is, then move northeast. However, since its so close to land, and since guidance has changed a few times in the last day, we should still watch this.  It is currently forecast to be a hurricane and pass 40N at 65W