Preliminary long-term ice forecast for winter navigation of 2006-2007 at the Baltic Sea and the Gulf of Finland

Preliminary long-term ice forecast for winter navigation of 2006-2007 at the Baltic Sea and the Gulf of Finland
(made on August 29-30, 2006)

This preliminary ice forecast is based on the research of the rules of large-scale atmospheric process in the Northern hemisphere held from the beginning of the current year. It also considers space-and-geophysical phenomena as well as ice-and-thermal state of adjacent northern seas featured with certain prognostics. This integrated approach enables to determine general baseline features of forecasted ice conditions.
In order to increase lead-time of this forecast up to 4-7 months it was decided at this phase not to consider actual data of key hydro-meteorological processes over pre-winter period. So general factors of the ice conditions (ice area, length of ice way along the navigable pass, flat ice thickness) featuring the type of ice conditions for the coming winter are represented in qualitative form.
Area of the Baltic Sea ice territory during the period of its maximum level (norm - 193, maximum - 402, minimum - 52 by 103 sq. meters) and seasonal maximum length of ice way along the basic navigable pass of the Gulf of Finland (norm - 242, maximum - 480, minimum - 50 miles) are expected to be close to the normal annual value.
Maximum thickness of natural flat ice in the water areas of the Vyborg Bay, Luga Bay and Bjorke-Zund strait is also expected to be close to the normal annual value. However, in the upper part of the Gulf of Finland it is expected to be a little bit lower than norm (the norm for Nevskaya – Ustyevskaya HMS is 55, maximum - 92, minimum - 21 cm).
Ice conditions in November – April may be characterized by higher spatiotemporal inconsistency. There is a possibility of both negative and positive anomalies of hydro-meteorological and ice conditions. In general it is expected that during the period of winter navigation in November-April 2006/2007 ice conditions will be close to annual normal type (moderate).
At the end of November after analyses of the current hydro-meteorological dada there will be basic long-term forecast developed based on more valid physical information. It is planned to carry out quantitative assessment of general data as regards the type of ice conditions. Further working out of this forecast is to be expressed in long-term forecast of the time for ice edge and fast ice boundary to reach certain meridians.

30.08.2006

Preliminary baseline meteorological forecast for October — May 2006/2007

In compliance with preliminary baseline meteorological forecast developed by the specialists of the department for long-term meteorological forecasts of Arctic and Antarctic Research Institute the following conditions are expected:
In October – pressure upper by 1.0 hPa. Air stream – mainly south-western with move to north-west. Temperature – above norm (4.7 ºС), average monthly: 5.8 град.С.
In November – pressure lower by 2.0 hPa. Air stream – western with frequent move to north. Temperature – below norm (-0.6 ºС) average monthly: -1,4 ºС.
In December – pressure lower by 3.0 hPa. Air stream – south-western with move to north-west. Temperature – above norm (-5.3 ºС) average monthly: –4.2 ºС.
In January – pressure lower by 4.0 hPa. Air stream – south-western with move to south-east. Temperature – below norm (-7.7 ºС) average monthly: –8.2 ºС.
In February – - pressure upper by 3.5 hPa. Air stream – south-western with move to north-west. Temperature – above norm (7.9 ºС) average monthly: –7.4 ºС.
In March – pressure lower by 5.0 hPa. Air stream – south-eastern, eastern, western. Temperature – below norm (-4.2 ºС), average monthly: -4,8 ºС.
In April – pressure lower by 2.0 hPa. Air stream – south-western with frequent move to south-east. Temperature about norm (3.1 ºС).
In May – normal pressure. Air stream – southern with move to north-west. Temperature – above norm (9.5 ºС) average monthly: 10.7 ºС.
Improvement of baseline meteorological forecast detailed as regards horizontal circulation periods is to be carried out starting from the end of October 2006.