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Hawaii Extended Forecast Discussion
(Caution: Version displayed is not the latest version. - Issued 1220Z Nov 23, 2014)
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Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
720 AM EST Sun Nov 23 2014

Valid 00Z Mon Nov 24 2014 - 00Z Mon Dec 01 2014

The 23/00z deterministic GFS/ECMWF seemed to closely follow the
short-term local forecasts. The frontal passage will likely
produce a sensible weather change---with a modified mid-latitude
Pacific airmass spreading across the island chain between 24/12Z
and 26/00Z.

Of note, the 23/00Z ECENS/GEFS maintained good mass field
continuity over the eastern half of the Pacific Ocean after day
3---versus their deterministic runs. So keeping extended forecast
at a nearly equal blend seems the way to go for day 5-7 in the
subtropical Pacific until the downstream/upstream pattern resolves
its continued variability.

The biggest differences in the Subtropics between the
deterministic GFS/ECMWF concern the timing of a second
mid-latitude trough progression (from the Aleutians) across the
Dateline and eastward to 160W around 29/00Z. The GFS maintains a
distinct separation of the mid-latitude wave train along
40N---enough of a distinction---to allow a second front to migrate
into the Subtropics---approaching Kauai from the northwest on day
6 (29/12Z). The ECMWF anticipates a consolidation of the long wave
pattern invof 135W---and is significantly faster with the Aleutian
system's incorporation into the mid-latitude flow pattern
downstream off the west coast of the Mainland. Therefore, it
carries a much-less amplified and weaker surface front (29/12Z).