Area Forecast Discussion
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FXUS61 KGYX 281017 AAA
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
617 AM EDT SAT MAY 28 2016
A hot day is in store for much of New England today...as high
pressure just off the south coast allows for warmth to build
north. Some humidity will even build into parts of New Hampshire
and make it feel a few degrees warmer than what the thermometer
reads. If heat is not your thing...relief is not far away. On
Sunday high pressure builds into the Maritimes...and turns winds
northeast and off the water. That will send a cold front through
eastern parts of the forecast area...dropping temperatures some 15
to 20 degrees from today. That front will hang around the area and
provide the focus for increasing showers and thunderstorms into
Sunday night and Monday as tropical moisture streams northward
into the area.
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --Update...Minor tweaks to account for latest trends in temps this
Previous discussion...Marine fog and stratus will mainly hang
tough near and N of PWM this morning...gradually lifting with
daytime heating. Then strong ridging aloft will build thru the
day...and allow skies to clear. A very warm air mass in
place...strong heating...and Wly flow across the interior will
mean afternoon highs reaching the low 90s for many. With dewpoints
in the 60s...some parts of the lower CT River Valley and ASH-MHT
corridor will see heat index values near 95. That will be the main
forecast concern today...though there will be a chance for
afternoon showers or storms near the coast. Some of the higher res
model guidance continues to show QPF developing during peak
heating. Given the rising heights...forcing will be weak and
anything more than widely scattered convection seems unlikely.
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.SHORT TERM /SUNDAY/...
Tonight into Sun...a S/WV trof crossing the Maritimes will see
high pres build in its wake. As high centers E of Nova
Scotia...the pres gradient will reverse across the region and turn
winds NEly and onshore. A backdoor cold front is expected to move
thru at least Ern zones Sun. Temps could be some 20 degrees cooler
vs today. Air mass aloft will remain quite warm still...so to the
W of the front could be another very warm day. This may include
much of the CT River Valley. At the same time that warmth aloft
may strengthen the inversion and make it all the more difficult to
rid the marine influence near the coast Sun. Precip chances will
revolve around scattered convection in the very warm air mass to
the W...and any low level rnfl or drizzle in the marine
layer...but overall forcing remains weak again.
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
High impact weather: heavy rainfall sunday night into monday may
cause localized flash flooding.
A broad ridge of high pressure aloft continues to be the main
large scale feature over the eastern United States through the
next week. This will keep generally mild temperatures in our
region under southerly flow. A weak shortwave will help to
initiate showers to start the week.
Our weather for Sunday and Monday will depend largely on the
strength of a tropical system. While Tropical Depression Two will
remain well to our south and is expected to move into South
Carolina, this tropical moisture will extend into Northern New
England. The strong Bermuda high will couple with an approaching
front to force a plume of very moist air northwards. Precipitable
water will approach 2 inches /near record levels/. Extensive
southerly flow around the Bermuda high will also bring warm air
allowing the freezing level to rise to around 12,000ft. The
tropical moisture and high freezing level will thus set the stage
for heavy rainfall. The moist airmass will yield convective
showers and thunderstorms. However since storm motion vectors
remain very weak /less than 10kts/ there is a risk for localized
flash flooding as any storms which form will have ample moisture
and not move very fast.
The font will push through Monday afternoon allowing for high
pressure to build back in from the Ohio River Valley. The ridge
remains in place through Tuesday and Wednesday bringing seasonable temperatures
with highs in the upper 70s and lows in the 50s. The upper level
pattern begins to shift by the end of the week as a trough digs
into the great lakes at 500mb. At the surface a low pressure
system moves through southern Canada dragging another cold front
through the forecast area for the end of the week.
.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
Short Term...Marine fog/stratus is hanging tough very near the
coast from coastal York into Cumberland Counties...advancing
farther inland on the Midcoast. This will remain the case thru
morning...before gradually lifting with daytime heating. Fog will
likely hang just off the coast during the day. Otherwise VFR
conditions prevail. This afternoon could see widely scattered SHRA
or TSRA develop near the coast...but coverage and location remains
Scattered showers and thunderstorms will impact all terminals on
Sunday afternoon into Monday. Brief periods of IFR rain will
occur across inland sites. For coastal sites expect ceilings to
drop to IFR with fog overnight Sunday into Monday. After Monday
afternoon conditions will improve to VFR through the end of the
Short Term...Winds and seas are expected to remain below SCA
thresholds for the weekend. Cold front pushing SWwd across the
waters Sun may allow for a period of seas approaching 5 ft outside
of the bays.
Large scale high pressure will remain over the region keeping
winds and seas below small craft criteria.
The pattern will remain warmer and humid into early next week. As
a result relative humidity values will remain moderate to high.
Winds will also remain on the lighter side...with high pressure
generally in control.