Marine Weather and Tide Forecast for Thomaston, ME

KEY MESSAGES
1. Areas of rain with embedded thunderstorms and moderate to heavy rainfall rates will continue through early morning with a chance of localized flash flooding.

2. High astronomical tides will continue into early this week and minor flooding remains possible due to residual surge.

3. Seasonable temperatures will return for much of the week. An unsettled second half of the week is likely with multiple rounds of showers in the forecast.

DISCUSSION
KEY MESSAGE 1 DESCRIPTION...

PWATs continue to surge ahead of an approaching cold front early this morning. All signs points towards a focused, but progressive area of moderate to heavy rainfall moving thru with the boundary. Flash flood guidance remains around 2 inches for 3 hrs. Upstream observations are showing mainly 1 to 1.5 inches with the heaviest rain so far, so things should be just heavy enough to keep a close eye on. Instantaneous rates are being estimated around 4 to 5 inches per hour in convective elements, so not only will torrential rain be possible, but any storm that does slow down or train briefly could cause some of that localized flooding. As of 230am, there has been a downtrend in persistent convection, and rates across a majority of the area have become more moderate. The Flash Flood Watch remains in effect as earlier rainfall percolates through the hydrologic system, combined with ongoing steady rates.

Once the front clears the area this morning conditions will rapidly improve for the afternoon.

KEY MESSAGE 2 DESCRIPTION...

High astronomical tides continue thru today. The evening tides are of greatest concern for Minor flooding, with the best chance for these levels to be met for Portland and Hampton again tonight. Wave action is expected to be less than last evening, but there has been a fairly consistent 0.5 to 0.75 foot residual surge for a few days now. Additional coastal flood headlines are possible.

KEY MESSAGE 3 DESCRIPTION...

Not much change on forecast temps this week. Should see widespread 70s and 80s during the day and falling back into the 50s to near 60 at night. Might even be able to sneak in some 40s in the northern valleys if we can sufficiently clear out.
Humidity begins to creep back up by Wed into Thu as the next storm system approaches.

That will come as an upper-level low moves eastward across Ontario and Quebec. As it approaches the lowering heights and warm advection may support afternoon showers Wed. But this system will be seasonably strong based on model forecasts right now. So I am anticipating that by Thu there will be strong synoptic support for rainfall as well as gusty winds. Convective guidance continues to suggest severe weather is a possibility, but that will largely depend on whether we can get any heating and resulting destabilization. Also at this time the rainfall amounts looking like a good soaking, but this time of year you always have to be cognizant of high rainfall rates as CAM guidance starts to become available closer to the event.

AVIATION /01Z MONDAY THROUGH FRIDAY/
Rain showers and embedded thunderstorms are moving through the western portions currently. Most guidance is now confined areas of IFR or lower to near the coast just ahead of the cold front early this morning. Otherwise widespread MVFR expected, with local IFR or lower in the heaviest convection. Overall there is also a lack of lightning in much of the precip at this hour, so I have opted to not include in TAFs unless I see a concerted uptick. Conditions will quickly return to VFR once the front passes thru during the morning.

Outlook:

Monday night: VFR conditions expected.

Tuesday - Wednesday: VFR conditions expected. Local MVFR or lower possible Wed afternoon in showers.

Thursday - Thursday night: Areas of MVFR or lower possible in rain and low CIGs .

Friday: Low CIGs may linger into Fri before clearing during the afternoon.

Friday night - Saturday: VFR conditions expected.

MARINE
Marginal SCA conditions expected thru sunrise ahead of the approaching cold front. Southerly winds will gust to around 25 kt and seas build to near 5 ft outside of the bays early. There may also be areas of fog on the waters, especially north of Cape Elizabeth towards sunrise as well. Winds and seas remain below SCA thresholds thru most of the week until the next system arrives Thu. Southeasterly winds turning southwesterly may gust up to 30 kt with seas building above 5 ft outside of the bays.

GYX WATCHES/WARNINGS/ADVISORIES
ME...Flood Watch until 8 AM EDT Monday for MEZ007>009-012>014-033.
Coastal Flood Advisory until 1 AM EDT Monday for MEZ023-024.
NH...Flood Watch until 8 AM EDT Monday for NHZ001>004.
MARINE...Small Craft Advisory until 8 AM EDT Monday for ANZ150>154.