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FXUS61 KGYX 181957 AFDGYX

Area Forecast Discussion National Weather Service Gray ME 357 PM EDT Sat May 18 2024

SYNOPSIS
A cold front moves offshore through the evening hours. High pressure strengthens over the region and just offshore early next week with dry conditions and well above normal temperatures. Scattered showers return by late Wednesday into Thursday as a cold front approaches and then crosses the region.
An upper level trough will keep scattered showers over the region Friday. High pressure builds in from the north next weekend, bringing a return to cooler conditions.



NEAR TERM /THROUGH SUNDAY/
Impacts: *No significant weather impacts expected

A decent area of rain has moved into southern New Hampshire and is expected to move northeastward hugging the coast and interior zones of Maine through the evening. More scattered showers continue to move northward through northern zones at this hour and are expected to clear out late this evening.
Additional showers may also come ashore in both Maine and New Hampshire before the upper and surface low fully move out of the region. Therefore kept likely PoPs on the coast through midnight to account for these lingering showers, but they will taper off quickly. Visible satellite imagery shows the clearing line behind this shortwave is just about getting into Vermont at this hour and may begin to reach northern and western New Hampshire after midnight. Still, clouds will keep temperatures in the lower 50s with those areas that see some clearing standing the best chance of dipping a bit cooler. Patchy fog will be much more widespread tonight, with locally dense patches likely especially in areas that saw decent rainfall.

SHORT TERM /SUNDAY NIGHT/
Impacts: * No significant weather impacts expected

Surface high pressure builds into the region Sunday which will keep us dry and kick start our warming trend. As clouds gradually clear from northwest to southeast we could end up with about a 10 degree temperature gradient between the Connecticut River Valley and the coast. Currently it looks like western zones warm into the low to mid 70s while the interior of Maine and New Hampshire top out in the mid to upper 60s. The coast of course stays the coolest, only reaching the lower 60s.

Sunday night looks cooler as skies remain partly cloudy. More areas stand a chance to drop into the mid to upper 40s. We will be drying out the lower levels as flow turns northwesterly under the ridge, so would expect fog to be very limited if it even develops at all. Confidence is low so it has been excluded from the forecast at this time.

LONG TERM /MONDAY THROUGH SATURDAY/
Overview... Heat makes its season debut this week as a ridge builds across the Eastern US. Temps gradually rise through midweek, and then humidity begins to increase late in the week ahead of a cold front. The front likely arrives sometime late in the week or early next weekend, but uncertainty remains on the arrival timeframe of this slowing front in the presence of the ridge.

Details...

This week will be dominated by a warm and summer-like weather pattern. In the presence of anomalously low pressure across much of the US and the Central Atlantic, an area of high pressure develops off the Eastern Seaboard. This sets up an increasing southerly flow by the beginning of the week, which gradually turns more southwesterly by midweek. Mostly sunny skies are expected for the duration of this timeframe, but some isolated mountain showers are possible across the mountains early and mid week in the afternoon.

Temperatures gradually rise each day from Monday through Wednesday. 70s to low 80s are expected inland, while the coastline remains in the 60s with increasing southeasterly flow.
By Tuesday, a warmer airmass continues to stream in, with winds becoming more southerly. This sends most areas away from the immediate coastline into the 80s, with upper 80s expected across southern New Hampshire. The coastline likely holds onto onshore flow most of the day, with temps in the 60s along the MidCoast, to low 70s along the southern coastline. Wednesday looks to be the warmest day, with south- southwesterly flow pushing the heat to the southern coastline. 80s are expected in most spots, with temps near 90 degrees across southern and western New Hampshire. The MidCoast will be a notable exception, with temps holding in the 60s with onshore flow continuing. Humidity will generally be low through this time frame, with dew points mainly in the 50s. This actually is dry enough to help shave a few degrees off the heat indices from the air temps.

By Thursday and Friday, humidity begins to increase as a cold front approaches and helps draw up some moisture from the south.
There remains uncertainty on the timing of this front amongst the ensembles. While the current forecast holds with NBM dew points, there is likely to be a period of time where dew points surge into the upper 60s ahead of the front late in the week.
Temps look to be trending downward during this time frame as more clouds and showers arrive. Showers and storms are expected to accompany the cold front when it arrives, but with the timing uncertainty POPs remain in the chance to low likely range during this timeframe. By next weekend, cooler air is expected to arrive as high pressure builds in from the north.

AVIATION /20Z SATURDAY THROUGH THURSDAY/
Short Term...A mix of MVFR and VFR ceilings will continue in the evening before widespread fog develops tonight trending most terminals toward IFR. Fog will dissipate Sunday morning and ceilings will have been lifting and clearing out overnight, so conditions should be VFR early on and remain there through Sunday night. Winds remain light through the period.

Long Term...Mainly VFR conditions are expected at most terminals from Monday through Thursday, but some coastal fog is possible at times at RKD Wednesday and Thursday. Showers and some thunderstorms bring brief restrictions on Thursday and Friday, especially to northern terminals. VFR conditions likely return by next weekend.

MARINE
Short Term...SCA seas look to continue through the first part of Sunday morning as slow moving low pressure passes east of the waters. Seas look to calm below SCA thresholds through the day and remain below through the night as high pressure begins to build over the waters. Northeasterly winds remain 10-15 kts through Sunday becoming, much calmer into Monday.

Long Term...High pressure builds across the Eastern Seaboard this week, bringing increasing south to southwesterly flow.
Areas of dense marine fog possible by midweek. SCA conditions are possible by Thursday with increasing southwesterly flow ahead of an approaching cold front.

GYX WATCHES/WARNINGS/ADVISORIES
ME...None.
NH...None.
MARINE...Small Craft Advisory until 10 AM EDT Sunday for ANZ150-152-154.

Dover, Cocheco River, Piscataqua River, New Hampshire, Tide feet

Salmon Falls River, Piscataqua River, New Hampshire, Tide feet

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