textproduct: Gray - Portland

WHAT HAS CHANGED

No significant changes in the short term. Some increase in potential light snowfall late Tuesday or Tuesday night, especially across southern locations.

KEY MESSAGES

1. Another round of soaking rain is expected Sunday, with a wintry mix possible in the mountains.

2. Drier and cooler weather is expected on Monday. There is then a low potential for some light snow or rain on Tuesday and Tuesday night. This will be followed by mainly dry conditions and moderating temperatures through the remainder of the week.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

The next precip event will arrive late tonight and Sun, as low pressure tracks across southern Quebec. Model guidance agrees the strongest forcing and highest QPF will be north and west of the forecast area. However, ensemble guidance also is fairly consistent that a solid soaking QPF event is likely for the forecast area. There is roughly a 3 in 4 chance that most areas will see between 0.25 and 0.5 inches liquid by the time things are all said and done. I say liquid equivalent because there is a question of how cold do temps get in the interim between cold frontal passage and onset of precip. Mesoscale model guidance drops readings across the north below freezing this morning and then barely bring them up above freezing during the afternoon. This is especially true for the western Maine mtns. Temps then sink back a few more degrees this evening before showers arrive with the mid level warm front. The Winter Weather Advisory covers this area nicely already, and I do not foresee a reason to expand at this time. Across those same northern zones precip may end as snow showers, as the next cold front comes thru and mixes out the low level inversion.

KEY MESSAGE 2 DESCRIPTION...

High pressure will allow for a dry but cool day on Monday with northwesterly wind gusts up to 25-30 mph. High temperatures will be into the 30s across the north with 40s to near 50 degrees south. It will remain dry on Monday night with lows mostly into the 20s. Attention then turns towards Tuesday as there is some increasing potential that a weak wave of low pressure may ride far enough north at the base of an H5 s/wv trof axis to bring some light precipitation to the region. Temperature profiles currently support mainly snow but with the high April sun angle and marginal surface temperatures, accumulations during the daytime will be tough to achieve. Light snow and/or rain may continue through Tuesday evening before ending overnight. There remains significant forecast uncertainty though and Tuesday could become another dry day. Regardless, Tuesday night will be cold with lows falling into the teens across the north with lower to middle 20s south.

Geopotential heights are then progged to increase Wednesday through the end of the week as flow becomes increasingly out of the southwest. This will allow for a gradual moderating trend with temperatures potentially becoming above average by the end of the week. Mainly dry conditions also are likely.

AVIATION /02Z SATURDAY THROUGH WEDNESDAY/

In the warm sector ahead of the cold front, patchy LIFR conditions in fog and low CIGs continues. As the front comes thru conditions will mix out quickly to VFR. The exception will be north of the mtns, where MVFR CIGs develop and continue thru morning. VFR conditions expected for most of the day otherwise.

Outlook:

Saturday Night: Areas of IFR or lower develop again in onshore flow. Showers possible thru the night, some freezing rain or sleet possible for HIE and points northeast.

Sunday: Local MVFR or lower possible in showers as cold front crosses the region.

Sunday Night: Return to VFR conditions, except for mtns where MVFR CIGs may linger.

Monday/Monday Night: VFR conditions with daytime NW wind gusts between 25-30 kts possible.

Tuesday/Tuesday Night: VFR conditions are currently favored but there is a low chance (30-50%) for some light rain/snow along with lower ceilings. The greatest potential for this is currently across southern TAF sites. Westerly winds at 5-15 kts.

Wednesday/Wednesday Night: VFR conditions expected. Southwesterly winds at 5-15 kts.

MARINE

A cold front crossing the waters will have offshore winds gusting to around 25 kt thru the mid morning. Later today winds will turn back onshore and steadily increase thru Sun as another storm approaches. SCA remains in effect for the westerly winds thru morning, but a new SCA or extension is likely for the onshore winds thru Sun night.

Westerly wind gusts up to 30 kts are possible on Monday before becoming northerly Tuesday night-Wed AM with gusts between 25-30 kts possible. Elevated seas of 3-7 ft outside of the bays are also possible on Monday.

GYX WATCHES/WARNINGS/ADVISORIES

ME...Winter Weather Advisory from midnight tonight to 10 AM EDT Sunday for MEZ007>009. NH...Winter Weather Advisory from midnight tonight to 10 AM EDT Sunday for NHZ001-002. MARINE...Small Craft Advisory until 2 PM EDT this afternoon for ANZ150- 152. Small Craft Advisory until noon EDT today for ANZ151-154.