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Office: GYX

FXUS61 KGYX 191119
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
719 AM EDT Thu Jul 19 2018

.SYNOPSIS...
High pressure will crest over the region today and will shift
offshore overnight. High pressure will hold offshore Friday
through Saturday. A warm front will approach from the south
Saturday night and will lift north into the region on Sunday.
A warm and humid air mass will prevail behind the front early
next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
700 Am Update...
Quick update to mainly adjust area temps/tds. Patchy valley fog
is quickly dissipating and skies are crystal clear across the
region. No majors planned to current forecast.

Prev Disc...
Another fine mid summer day on tap as high pressure gradually
crests over the region by late in the day. Will see a chilly
start to the day in valleys in the mountains and foothills where
temperatures are already in the 40s. Highs today will top out
near normal ranging from the mid 70s north to the lower 80s
south.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
High pressure will slide offshore overnight and will hold there
through Friday as quiet weather continues across the northeast.
Looking for clear skies Thursday night with lows from the mid
40s to mid 50s. Return flow will bring slightly warmer
temperatures on Friday with most areas reaching the lower to mid
80s under mostly sunny skies.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Not much change to the forecast as latest 00z deterministic
guidance and latest forecast ensembles continue to be in general
agreement with the upcoming pattern change. Dry weather will be
replaced by a tropical airmass by Sunday and should continue in
place through much of next week. This will mean we stand a good
chance at beneficial rainfall.

High pressure ridging in place across the northeast should
provide fair weather Friday night into Saturday. However, with
tropical air mass looming to our south, low clouds and some fog
may begin to roll in late Saturday along the coast as winds turn
more onshore.

A short wave trough originating from off the southeast US coast
will swing northward Saturday night into Sunday along with
varying degrees of strength of attendant SFC low pressure seen
the latest model guidance. This short wave trough will bring
north a tropical airmass. In fact precipitable water values
should go from around 50% of normal to nearly 200% of normal in
roughly 12-18 hours ending midday Sunday. That is a serious air
mass change and one that will support occasionally heavy rain on
later Saturday night and Sunday along with a few thunderstorms.
Confidence in rainfall totals not overly high at this time as
degree and placement of forcing for ascent is still in question.
There may even be some mesoscale enhancement as some guidance
shows coastal front development.

Confidence is high enough in the occurrence of rainfall that we
can go with PoPs around 80 percent on Sunday.

Thereafter, Bermuda high pattern remains in place allowing for a
very moist airmass to persist through midweek. Pegging down
forcing mechanisms for rainfall timing is difficult this far out
in time. However, there will be substantial chances for showers
and thunderstorms Monday through Wednesday - mainly during the
afternoon hours with peak heating and quite possibly mainly in
the interior zones where less subsidence may be found. Will have
to watch out for localized flash flooding during this period
with very high PWATS in place.

&&

.AVIATION /11Z THURSDAY THROUGH MONDAY/...
Short Term...VFR today through Friday.

Long Term...VFR conditions likely Friday night through Saturday.
However, low clouds and vsbys restrictions in fog likely to
develop coastal terminals Saturday night with moistening onshore
flow. IFR conditions expected Sunday most locations in rain
along with a few thunderstorms. Low conditions likely continue
Sunday night with low clouds. Some improvement possible Monday.

&&

.MARINE...
Short Term...No flags as high pressure keeps winds light.

Long Term...SCA conditions, especially 5+ foot seas, possibly
develop Saturday night and may last into early next week.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.

&&

$$



Office: CAR FXUS61 KCAR 191007 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 607 AM EDT Thu Jul 19 2018 .SYNOPSIS... High pressure will slide south of the area today through Friday then move east into the Atlantic on Saturday. Low pressure will approach from the south on Sunday. && .NEAR TERM /THROUGH TONIGHT/... 6 AM Update...The sky remains clear across the area. Some isolated patchy fog in the northern river valleys is dissipating. Temps were adjusted early this morning to account for some lower readings in the normally colder valleys. Otherwise, no significant changes this hour. High pressure cresting nearby to the south today will bring plenty of sunshine and a comfortably dry day. A few high clouds may stray into far northern areas this afternoon into this evening. Otherwise, tonight will be another mostly clear night. Dew points will be low today, generally in the upper 40s to near 50. The humidity will begin to increase just a bit this evening as dew points rise into the low 50s and slightly more humid air starts to move in from the west around the high. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... Hot and increasing humidity for this term. High pres is forecast to slide into the Gulf of Maine into Saturday w/very warm temps and increasing dewpoints expected. Plenty of sunshine if forecast leading to daytime temps shooting into the mid and upper 80s both days. The caveat to this will be along the coast up into the Bangor region especially on Saturday w/a sse flow setting up leading to cooler temps. There is the potential for some fog and low clouds to set up across the Bangor region down to the coast by early Saturday morning. The sse flow around the high will bring llvl moisture in from the Gulf of Maine. The 00z NAM and SREF point to the potential for some fog development by early Saturday morning. Attm, leaned w/patchy fog the aforementioned areas. Confidence attm is not high enough to push for widespread coverage of the fog. The NAM and SREF also indicate some light precip making it into the Downeast region on Saturday. The GFS holds this back until Saturday night. The ECMWF and Canadian Global bring some light precip into the Downeast and Bangor region by late Saturday afternoon. Given the discrepancy of the timing, decided to stay w/20-30% pops for light rain/drizzle by late in the day on Saturday for the Bangor and Downeast. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... A weak sub-tropical wave is forecast to lift n from the coastal Carolinas into the Northeast late Saturday night into Sunday. The long range guidance including the ECMWF/GFS and Canadian Global show the wave weakening as it lifts across the Northeast on Sunday. All the long range guidance forecasts measurable precip w/some of the guidance such as the ECMWF and GFS bringing 0.50 to 0.75 inches of rainfall. The Canadian Global is light on the rainfall keeping the ridge axis over the region. The heaviest rainfall from this event looks to be across the Bangor and Downeast region. In collaboration w/GYX, decided to go w/60% pops for the aforementioned areas which includes portion of the Piscataquis Valley due to upslope. Further n, went w/40-50% pops. There does appear to be some elevated instability to support some tstms for the southern sections of the CWA. This first round of rainfall look like it could exit the region by Sunday night and tried to show this w/scaling the pops back to the chance category. A tropical like airmass looks to set itself in place w/strong high pres anchored in the western Atlc and a closed low to the w leading to a ssw. This ssw is forecast up through 300mbs tapping both the Gulf of Mexico and Atlc ocean. This will allow for moisture to set in place. Dewpoints are forecast to be on the increase climbing well into the 60s to around 70F. Therefore, warm and humid into mid week. Disturbances in the upper flow will be the forcing to allow showers and tstms to set up through at least mid week. Decided to follow the daycrew's thinking of carrying tstms for the afternoon into the evening for each day. Given the tropical airmass, heavy rainfall looks to be a high probability. There is still time to assess this situation w/the later model guidance. && .AVIATION /10Z THURSDAY THROUGH MONDAY/... NEAR TERM: VFR conditions are expected across the region today and tonight. SHORT TERM: VFR into Saturday. The exception will be for KBHB and KBGR as fog and stratus on Saturday could lead to MVFR/IFR and perhaps even LIFR. Sunday looks like conditions could be MVFR/IFR for all terminals w/rain and possible tstms for KBGR and KBHB. && .MARINE... NEAR TERM: Winds and seas are expected to be below SCA today and tonight with generally tranquil conditions over the waters. SHORT TERM: Winds are forecast to be around 10 kts into Saturday w/seas of 3 ft. The winds are forecast to increase on Sunday as a weak sub-tropical wave lifts up from the coastal Carolinas. Wind speeds could hit 15+ kts especially over the outer waters. The more notable item here is the sse flow into Sunday veering to the ssw w/an increasing period. Wave heights are shown to build to 4-6 ft into Monday w/the highest waves over the outer zones. Fog will be nuisance for navigation Saturday morning right through Sunday. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...Bloomer Short Term...Hewitt Long Term...Hewitt Aviation...Bloomer/Hewitt Marine...Bloomer/Hewitt