Storm Forecast

Storm Forecast
Valid: Sat 18 Jan 2014 06:00 to Sun 19 Jan 2014 06:00 UTC
Issued: Fri 17 Jan 2014 18:55
Forecaster: PISTOTNIK

A level 1 was issued for an offshore area of Portugal and Morocco for severe wind gusts.


A quasi-stationary weather pattern has established with a cold anticyclone over Scandinavia and Western Russia and a long-wave trough over Western Europe. This configuration results in a deep Southwesterly flow and warm air advection over Central, Eastern and Southern Europe, including a Saharan elevated mixed layer that overspreads the Central Mediterranean region. In contrast, cool air is pushed southward into the Iberian Peninsula.


... Western and Central Mediterranean region ...

Steepening lapse rates and adequate low-level moisture support the buildup of a few hundred J/kg of CAPE during the forecast period. QG lift ahead of the main trough axis may allow isolated thunderstorms over the Western Mediterranean Sea, mostly embedded in widespread cloudiness and stratiform rain. Their struggle to become surface-based and a lack of vertical wind shear should preclude any severe weather.
Similar conditions arise with upslope flow along the Liguarian coast and - very late in the forecast period - in coastal Slovenia and Croatia. However, at least till the end of the current forecast period, no rainfall accumulations sufficient for a level 1 are expected yet.
Further Southeast, deep-layer shear increases to 25 m/s over the Tyrrhenian Sea and Italy, but capping beneath the Saharan elevated mixed layer will be too strong to enable convective initiation.

... Portugal, Morocco ...

A wave swings southeastward on the back side of the main trough, accompanied by a pronounced tropopause anomaly. Once more a few hundred J/kg of CAPE may materialize in its warm sector. With 850 hPa winds peaking over 25 m/s, isolated severe wind gusts are possible in the second half of the forecast period, though the confidence in the formation of a convective line is limited.

Otherwise, maritime convection in a weakly sheared environment beneath the base of the long wave trough may produce isolated lightning strikes over the Atlantic Ocean.

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