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Area Forecast Discussion (AFD)

Issued by Caribou, ME (CAR)

FXUS61 KCAR 201959

Area Forecast Discussion
National Weather Service Caribou ME
359 PM EDT Sat Apr 20 2019

A stationary front will slowly lift northward tonight as a warm
front and bring much warmer and humid air into the region for
Sunday. Low pressure will approach from the south later Tuesday.

The stationary front actually moved slightly southward towards
the coast this afternoon and resulted in a chilly day north of
the front with highs in the 40s. The cold air will finally give
way gradually tonight. The large Atlantic high will build 
northwestward overnight and help push the cold air back 
northward. The last widespread batch of heavier showers...and 
even an isolated currently pushing northward 
with the warming aloft. The thermal ridge at H925 will provide a
base for elevated instability. These showers could be locally 
heavy with PWs pushing an inch and a half and a strong LLJ, but
shouldn't last too long as they progress northward out of the 
state by later this evening. Scattered showers will remain over 
the area through the night as an occluded front associated with 
the low in the Ohio River Valley will remain over the area and 
Atlantic moisture will continue to stream northward along the 
occlusion. The frontal inversion will remain in place all night 
with low clouds and increasing fog as much higher dew points try
to advect northward. Some patchy drizzle may also occur from 
low clouds trapped under the inversion. On Sunday, the occlusion
will continue to affect the Downeast counties with rain, fog 
and a cool onshore flow. Meanwhile, further inland, a drier 
southwest flow will develop and the inversion will break in the 
far northwest for sure...resulting in 70F highs with the warm 
air mass. In between the two extremes, the inversion will be 
slow to break and only permit highs in the low to mid 60s by 
later in the afternoon.

Upper level low pressure is expected to pass to the south of the
region on Monday. This will produce showers on Monday,
especially over the east and southeast. The low pressure system
is expected to move to the east on Tuesday as a narrow ridge of
high pressure builds in from the west. At the same time another
area of low pressure will approach from the west. Skies are
expected to remain cloudy through this time period with showers

Low pressure is expect to approach from the west Tuesday Night
and Wednesday then cross across Northern Maine Wednesday Night.
This system will produce rain through this time period. The low
will move off to the east Thursday Night with high pressure
cresting over the region. Another area of low pressure will move
across the region on Friday.

NEAR TERM: IFR to LIFR cigs are expected for all sites until
late Sunday morning when the trend will be towards MVFR cigs or
no cigs. Heavier rain showers will cross the area this evening
with a very small chance of embedded thunder. LLWS is expected
tonight into Sunday morning with south winds up to 45 kts just
above light southerly surface winds.  

SHORT TERM: Expect VFR/MVFR conditions on Monday and Tuesday.
MVFR/IFR conditions are expected Wednesday and Thursday.

NEAR TERM: The Small Craft Advisory has been cancelled in favor
of a Small Craft Advisory for Hazardous Seas. Winds have been
decreasing in the stable humid air over the cold waters and that
trend will continue through Sunday. Fog will be an issue over
the waters tonight and Sunday.

SHORT TERM: Have used the Nam to initialize winds however will
continue to lower all model winds by 10 percent due to cold sea
surface temperature and expected strong warm advection. For
Waves: Long period swell (6-7 feet/10-11 seconds) will be the
primary wave system on both Monday and Tuesday. This wave system
was generated in a long fetch extending well to the south of the
Gulf of Maine so it is not expected to significantly subside
until Wednesday. There will also be southerly winds present but
the expected wind speed is not sufficient for additional build 
of the swell. Total Water Level: High tide levels are close to 
highest levels of the month next few days in coincidence with a 
full moon however storm surge is expected to remain below 1 foot
so no problems are expected in coastal areas. In Bangor fresh 
water run-off continues to increase anomaly at low tide to 
around 5 feet. At high tide the anomaly is increasing to near 
almost 2 feet. This may be a concern as the high astronomical 
tide is elevated due to fresh water runoff over the next 2 days.

Rainfall tonight and warmer temperatures on Sunday continue to
put hydro issues at the forefront of area weather concerns. The
small streams and roads will remain a concern into this evening
with the last batch of heavier rainfall. At this point, after as
much an inch and half of rain plus snowmelt, there haven't been
enough road closures and other issues to justify an upgrade to
a broad areal Flood Warning to replace the current Flood Watch.
Will highlight the trouble spots in the Flood Watch statement. There
are new river point Flood Warnings for minor flooding at four 
points: Big Black River near Big Black, Piscataquis River above
Dover Foxcroft, Piscataquis River at Medford and the Penobscot 
River at West Enfield. The point Flood Warning on the 
Mattawamkeag remains in place with moderate flooding expected. 
In terms of ice jams, the focus remains on the Aroostook River 
at Washburn where a jam remains locked in place and the areal 
Flood Warning remains valid. There are numerous roads affected 
as well as a bridge and some homes in this warning area. On the
Saint John River, the only remaining larger scale ice jam area 
known is near Saint Francis and does not appear to be a 
significant enough threat to prompt any warnings or advisories 
at this time. 

ME...Flood Watch through Monday evening for MEZ001>006-010-011-015-
MARINE...Small Craft Advisory for hazardous seas until 8 PM EDT Sunday 
     for ANZ050-051.

Near Term...MCW
Short Term...Mignone
Long Term...Mignone