Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Caribou ME
620 PM EDT Thu Jun 22 2017
a warm front will lift across the region Friday, followed by a
cold front Friday night into Saturday. A series of upper
disturbances will cross the region through the weekend, keeping
the weather unsettled.
Near term /through Friday/...
620 PM update...
very pleasant evening continues across all of northern and down
East Maine this hour. Clouds will be on the increase late this
evening in association with approaching warm front from the
southwest. Current forecast is in good shape and see no reason
to make any significant adjustments with this update.
the potential for heavy rain on Friday is the main concern for
the near term.
Low pressure is currently spinning over the Great Lakes will shift
eastward across Quebec tonight and Friday. Meanwhile, the warm front
that extends southeast from this low will lift north over the
northeast Continental U.S.. southwest flow out ahead of the Quebec low will
draw moisture northward from the remnants of Tropical Depression
Cindy, and this moisture will interact with the warm front to
produce a swath of rain across the region. Precipitation will
approach our western sections late tonight, but should begin in
earnest during the mid to late morning hours on Friday. With pwats
of 1.5 to 2.0 inches and warm-cloud depths of 11-13 kft, expect
we'll see efficient rainfall processes. The highest amounts will
occur across the North Woods up through the Saint John valley,
accompanying the strongest warm advection. These areas could pick up
three-quarters of an inch or more through daylight hours on Friday.
Have therefore continued to mention heavy rain in the forecast for
these locations. Central and downeast areas will mainly see a half
inch or less, with only a tenth or so along the coast. Have also
continued the chance of thunder for Friday afternoon. The amount of
instability is in question owing to plentiful cloud cover, but there
should be enough, especially over western areas, to allow for a few
Short term /Friday night through Sunday/...
widespread rain, possibly with some embedded thunderstorms,
will be ongoing Friday evening as a front approaches from the
west, and it may be heavy up north. As the front swings through
the County Warning Area overnight into early Saturday, anticipate a shift to
more showery precip, and decreasing pops in general. Some low
stratus and patchy fog is also possible before the front moves
A weak upper-level disturbance and associated vorticity
Max may kick of a few showers up north Sat afternoon. A more
robust shortwave may then pass through Sat night into early sun
am, which the GFS and Canadian both show bringing a few showers
to central and downeast areas. However, for both shortwave
features, kept any pops low-end chance at best. As a broader
trough approaches from the west Sunday afternoon and evening, a
broader area of showers is possible across most of the County Warning Area.
Long term /Sunday night through Thursday/...
the active upper-level pattern will keep weather fairly
unsettled through the long term. A cold front expected to push
through Monday morning will bring further showers to the area
Sun night into Mon am. Given the active weather pattern with
multiple shortwaves, it's not surprising that disagreements
between models on timing and placement of features develops in
the long term, thus pops were generally kept under 50 percent
during the period.
Aviation /22z Thursday through Tuesday/...
near term: VFR conditions will persist through 12z Friday. Then
MVFR conditions will become more likely, especially at the
northern terminals, as an area of rain spreads across the state.
The rain may be heavy at times Friday afternoon, possibly
reducing visibility and dropping ceilings to IFR levels, mainly
at the northern sites.
Short term: would expect IFR conditions to continue Fri night
into early Sat am in heavy rain and possible patchy fog.
Improvement to MVFR and VFR then expected Sat PM into sun,
except for patchy IFR possible around any showers. Some more
widespread IFR conditions possible Sun night into Mon am, and
again during the day Tue, in scattered shower activity.
near term: a Small Craft Advisory has been issued for late Friday
afternoon through Friday night. Winds and seas will both build
through the day as a warm front lifts across the waters. Gusts to 25
kt and seas of 3-6 feet are expected by Friday evening.
Short term: winds will continue to gust to near 25kts Fri night,
and seas will build to 4-7ft overnight into Sat am, thus the Small Craft Advisory
was continued into Sat am. Winds and seas are both expected to
decrease Sat PM, and seas will continue to decrease into sun as
winds remain offshore.
Marine...Small Craft Advisory from 5 PM Friday to 8 am EDT Saturday for