MattTarrant

Tropical Depression 10 has formed in the central tropical Atlantic and is forecast to move WNW/NW. Forecasted to be close to the Northern Leeward Islands by Friday as a #hurricane. The average (1981-2010 climatology) date for the 4th Atlantic hurricane is September 21 (@Philip Klotzbach).

33.7

Now saying 38c...

38.3c, Kew Gardens, Thursday

More a phrase than a word no? No on a serious note both the FV3 and Legacy attempt to deconstruct the trough ECM style. Regarding the N Atlantic trough it seems relevant to notice that the ECM 12z was more amplified initially allowing for the newfoundland trough to aid the pattern transition.

Raw ECM data shows 36 at 1:00 PM next Friday...So only imagine the peak temp...

Interest is growing in the Gulf of Mexico over the next few days as an unconventional system is forecasted to develop into a cyclone, the National Hurricane Center predicts an 80% chance of formation in the 5 day range. Uncertainty prevails but a tropical storm or weak hurricane is likely to be situated towards the Louisiana/Texas border by Friday/Saturday.

The ECMWF is introducing a substantial upgrade to its Integrated Forecasting System (IFS) today (12z run). This is a notable update and includes several fundamental changes. Key changes include: . Improved continuous data assimilation (Ensemble of Data Assimilation (EDA) Increased from 25 to 50) . Wave model changes (New parametrizations for wind input & deep water dissipation of waves) . 3D aerosol climatology replaces 2D climatology. . Minor updates/improvements to convection & radiation scheme Appreciable improvements include 1 - 5% reduction in upper air and 0.5 - 2% surface parameters errors in the extra tropics.

26.2°C, Kew Gardens

Two trough features were on the fax charts, so not out question to see an area of organised showers push through. It's interesting to note a subtle difference between the ECM/GFS Vs UKMO regarding 850hpa temps, the former's have them 1/2 lower. However, at best a transient cover at low levels anyway.

Slide 51 comments on stratospheric errors . Q3FY16GFSBriefingNCEPOD.pptx

Not quite as sharp as the ECM 0z but an excellent effort, 8/10.

Your the one that doesn't have a clue. It's not exactly new musings that the reversal (not really the warming) at 60hpa in the stratosphere was gradually pushed backed in time, with modelling being somewhat progressive in that nature. The 1st/2nd is almost guaranteed now as the reversal date. The Met Office, draw conclusions from an accumulation of model data, with even the best insight in the world it is impossible to predict that the models were being progressive. There is also an issue as to the extent of coupling between the stratosphere and the troposphere, ie the extent of downwelling. The models have been loosely trending to a more -NAM setup with lower u values in the 100 - 300hpa region (see ECM), though there is still considerable uncertainty in this region. Now watch, in conjunction with the stratospheric plots, the extent of anomalous heights across the pole region as to a rough guide to the extent of downwelling.

https://journals.ametsoc.org/doi/full/10.1175/1520-0442(2004)017<2584%3ATLCOTN>2.0.CO%3B2 This research paper could be of use . Cheers Matt

Well this is an example from my families home in south west England back in March when the freezing rain was very serious. Be careful.

That's why people complaining about an amber warning will likely look silly...

'ICON (13km)' DOES NOT EQUAL ICON - EU (7km). Uncertain as to whether the model physics are the same (ie Icosahedral Nonhydrostatic), though the vertical and horizontal resolution are appreciably different. ICON (13km) = 60 Vertical Layers ICON - EU (7km) = 90 Vertical Layers

The control run is run at a lower resolution but has no adjustments made to the raw data (same as GFS Op).

An upper tropospheric (250mb) low fed some dry air but also led to shear on the southern side of Florence. This was mentioned in the recent NHC discussion, recent imagery however from the GOES - 16 shows very cold cloud tops now on the southern side. However, early land interaction seems to be limiting this from wrapping around the eyewall, thus intensity probably won't change much despite the high ocean heat content available to Florence .

The UKMO reflects the comments you made about damage to Wilmington, I don't think with modern building codes damage will be quite to the extent you mention, but serious damage nonetheless!

Out of interest, where do you find these?

The Latest ECM confirms this development (at least within the operationals) that landfall is increasingly likely, indeed a major hurricane as well Edit: Beat me to it