Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Gray ME
909 am EDT Tuesday Apr 21 2015
low pressure will drive an occluded front across the region today
preceded by locally heavy rain and scattered thunderstorms. Low
pressure north of the Great Lakes will gradually weaken as it
drifts southeast into New England Wednesday through Thursday. Low
pressure will continue to weaken as it meanders north of New
England Friday through Saturday.
Near term /until 6 PM this evening/...
occlusion now lifting across the County Warning Area this morning and driving
remaining moderate to heavy shower activity northeast.
Thunderstorms are still ongoing mainly offshore with some cells
over downeast Maine. Scattered light mountain showers are also
moving slowly north-northeast. These mountain showers may hang around but
otherwise the rain has ended for most of the region.
We should have plenty of warming today with the rain moving out
early. Will be looking at bumping up temperatures a few degrees
from current forecast shortly.
at 06z...a 984 millibar low was centered near southern tip of
Hudson Bay with occluded front extending southeast to a 999
millibar vicinity of the Delaware-Maryland-Virginia. Strengthening low level jet and
onshore flow is generating several bands of moderate to
occasionally heavy rainfall on National Weather Service Doppler radar mosaic in advance
of the warm frontal occlusion. Lightning detection indicated stray
strokes across the County Warning Area at moment...with a much
more impressive area of convection across southern and western
New England pivoting north and east towards our area. This area
of convection will translate north and east across our forecast
area this morning in advance of the occlusion with locally heavy
rainfall and possible poor drainage and urban flooding. This
additional rainfall may also push some of the rivers to bankfull
by late today and tonight. Consequently...no changes to present
Flood Watch were made. We'll see rain taper from southwest to
northeast today with passage of the front along with partial
Short term /6 PM this evening through 6 PM Wednesday/...
we'll see partly cloudy skies under weak ridging tonight before
the next impulse rotating around the upper low over the Great
Lakes brings a return of clouds and showers on Wednesday.
Long term /Wednesday night through Monday/...
a broad upper level closed low over the Great Lakes will keep
unsettled weather across the forecast area through the rest of
week and into the weekend as it slowly drifts east to over New
England. Expect several short waves to rotate around the base of
this system at times enhancing the shower activity.
Expect generally cloudy skies and scattered showers Wednesday
night and into the weekend.
Shower activity will diminish over the weekend but skies will
remain mostly cloudy with scattered rain or snow showers in the
Aviation /13z Tuesday through Saturday/...
short term...MVFR will deteriorate to LIFR and IFR as heavier
rain and scattered thunderstorms move in. Rain may be lighter at khie where we
will see the rain shadow effect. Also some snow may mix in late in
the North. East winds may gust to 35 knots at times. Some improvement
by middle morning Tuesday as rain moves east. VFR with local MVFR in
fog tonight then areas of MVFR on Wednesday in showers.
Long term...areas of MVFR ceilings through Saturday.
short term...easterly winds and seas continue to build this
morning ahead of an occluded front. A Gale Warning remains in
effect through 2 PM today. Winds will decrease behind the front
but a Small Craft Advisory will likely be needed for waves through Wednesday
Long term...sca's may be needed Thursday and Friday.
onshore flow brings a soaking rain today. More cool unsettled
weather with showers will linger through the end of the week.
a widespread 1 to 2 inches of rain is expected through today.
However...given strong moisture inflow...localized amounts of up
to 3 inches could occur. This would lead to flooding problems...
especially in areas where snow melt is still occurring. A Flood
Watch remains in effect.
ME...Flood Watch through Wednesday morning for mez007>009-012>014-
New Hampshire...Flood Watch through Wednesday morning for nhz002>015.
Marine...Gale Warning until 2 PM EDT this afternoon for anz150>154.