Scientific Forecaster Discussion
fxus61 kgyx 250805
Area forecast discussion
National Weather Service Gray ME
405 am EDT Tue Jul 25 2017
high pressure builds in from the west today...bringing drier
weather and clearing. It will shift offshore on
Wednesday...allowing some warmer air back into the region. A
cold front pushes toward the area on Thursday...with low
pressure possibly forming along the front bringing another
chance of rain and cooler temperatures.
Near term /until 6 PM this evening/...
low pressure and yesterdays rain will move off into the Gulf of
Maine with improving conditions through the day. A secondary
area of low pressure remains in upstate New York and scattered
showers will continue through the north through the morning. Low
clouds will help to keep moisture around through the morning
hours, with some patchy fog and drizzle possible through
Clouds will decrease by afternoon as the low moves out and this
will allow temperatures to climb back to near 70.
Short term /6 PM this evening through 6 PM Wednesday/...
high pressure will build into the region tonight. With clear
skies and lingering moisture expect valley fog to form
throughout the region with dense fog in some of the valleys.
Moisture will be the limiting factor in the overnight low
temperatures. In the north more dry air will allow temps to fall
into the upper 40s while further south will remain in the mid
Wednesday high pressure will remain overhead with clear skies.
Temperatures will return to near 80 inland, but cooler on the
coast where an afternoon sea breeze will develop.
Long term /Wednesday night through Monday/...
high pressure will be shifting east of the region Wed night
allowing return flow to set up in its wake. At this time the
high pressure is forecast to be expansive enough and have a
large enough dry push that any marine fog/stratus should be
scoured out of the Gulf of ME by this time. Despite return
flow...it does not look like higher dew point air mass will have
enough residence time over the cooler water to create much of a
fog issue ahead of the approaching cold front. Though that could
change if the front is delayed.
The lead S/WV trof will push attendant front towards the area
Thu afternoon. With sufficient heating a strong storm or two is
possible...as a seasonably strong 300 mb jet streak crosses
overhead. Beyond that there is still considerable uncertainty as
to what happens along the trailing portion of the front as the
secondary S/WV trof approaches. Model guidance is in strong
agreement that convection will fire across parts of the Midwest
and track ewd. The European model (ecmwf) remains a bit of a nrn outlier
regarding track of that convection...but after consecutive runs
being well north the 25.00z European model (ecmwf) has shifted back S. This better
matches the GFS and CMC...as well as its own axis of 800 mb
potential temp advection. As a result the forecast is starting
to look mainly dry Fri for nrn zones...with the best chance for
precip to be near the Massachusetts border.
Beyond Fri...the ern Continental U.S. Will remain in broad trofing...though
the northeast may get into a little S/WV ridging. This will lead
to pretty weak forcing and low precip chances thru the
weekend...along with no significant heat or cold shots.
Aviation /07z Tuesday through Saturday/...
short term...existing MVFR cloud deck will persist through mid
morning before conditions return to VFR. Look for IFR fog in the
valleys tonight as good rational cooling sets up with high
pressure overhear. The high will remain through Wednesday
keeping VFR conditions.
Long term...VFR conditions Wed night into early Thu will prevail
as high pressure slides offshore. A cold front will approach Thu
afternoon with shra/tsra. Any convection could bring MVFR or
lower conditions...but confidence is low in timing and placement
of cold front due to typical modeling errors at this time range.
VFR conditions are expected to return behind the front to start
short term...high pressure will build over the waters today
allowing winds and seas to gradually diminish.
Long term...sly flow will develop late Wed as high pressure
builds offshore. Sustained sly flow may allow seas on the outer
waters to near 5 ft for a time Thu ahead of the approaching cold
front. Otherwise winds and seas are expected to remain below Small Craft Advisory
Marine...Small Craft Advisory until 6 PM EDT this evening for anz150-