Forecast Update

Forecast Update
Valid: Mon 07 Nov 2011 14:00 to Tue 08 Nov 2011 06:00 UTC
Issued: Mon 07 Nov 2011 14:06
Forecaster: ESTOFEX

A level 1 was issued for the W-Mediterranean and NW-Italy mainly for heavy rainfall. Isolated excessive rainfall is possible.


Please refer to the main outlook.

Update of the side-note":

Latest satellite data reveals a gradually better organized depression in the western Mediterranean. The center is at least partially covered by a central dense overcast feature with strong pulsating cells especially along the northern/eastern part. It still ingests a somewhat more stable/dry air mass from the south with a diminishing trend, so conditions look promising for further organization. Latest ASCAT data indicates a broad and asymmetric wind field with maxima still displaced from the center, which is typical for an organizing subtropical cyclone (in the range of 30-35 kt). Phase diagrams also support that this depression continued to structure its shallow warm core during the past 12 h and indicates further organization for the upcoming 24 h. Using the Hebert Poteat technique and keeping in mind the better organized structre of the main band and deeper/somewhat more persisting DMC along the center, a classification of ST 2.5 would be a reasonable, although probably quite an optimistic guess, given still transientness of the convection ( ST 2.5 represents an intensity of 35-40 kt). It has to be stressed out that no real time surface data is present to support that intensification rating.

Overall model guidance agrees in pushing that feature northwards towards S-France but with a significant cone of uncertainty. Also intensity guidance diverges with some models indicating a gradual weakening trend, whereas WRF-NMM f.ex. has some further strengthening until landfall. Current thinking is that some further organization seems likely, before geopotential heights gradually increase on Tuesday. In any case, there seems to be no direct affect to S-France until 06 Z, despite increasing easterly winds along the coast and stronger downpours in onshore moving bands.

Minor changes were done to the rest of the outlook as thunderstorm probabilities gradually decrease along the E-coast of the Adriatic Sea. Models still indicate heavy to excessive rainfall along the Ligurian coast all the way to far S-Switzerland especially during the nighttime hours. Despite some models again indicating excessive rainfall amounts in that region, confidence is not high enough to upgrade to a level 2 (also regarding minimal CAPE, so the main activity will probably be more stratiform in nature).

We also downgraded all 50-% thunderstorm areas.

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