textproduct: Caribou

WHAT HAS CHANGED

- 7:28PM UPDATE...Minor tweaks to skies and POPs over the next 12 hours. Otherwise this is an aviation update for the 00z TAFs, see below for more details.

KEY MESSAGES

1) Rain will occur tonight into Wednesday morning, with showers and thunderstorms Wednesday afternoon. There is a marginal risk for severe thunderstorms Wednesday afternoon and evening. Locally heavy rainfall is possible which could lead to minor urban flooding.

2) Dangerous Rip Currents and potentially High Surf along the Downeast coast Wednesday.

3) Potential for a system moving in Monday/Tuesday, bringing some wetting rainfall.

DISCUSSION

KEY MESSAGE 1...Rain will occur tonight into Wednesday morning, with showers and thunderstorms Wednesday afternoon. There is a marginal risk for severe thunderstorms Wednesday afternoon and evening. Locally heavy rainfall is possible which could lead to minor urban flooding.

KEY MESSAGE 1 DESCRIPTION... Low pressure lifting across Quebec province will begin to draw a warm front across the region tonight. Overrunning rain will expand across the region early tonight then persist through the remainder of the night. Precipitable water values increase to around 2 inches Downeast tonight, with 1.50 to 1.75 inches across northern areas. A strong low level jet will also cross Downeast areas overnight. Elevated instability will also support isolated/scattered thunderstorms overnight. With the higher precipitable water values and support from the low level jet, expect the heavier rain totals tonight will occur Downeast. The warm front will exit the region Wednesday morning, with the steadier rain ending in the wake of the warm front. The warm sector will cross the region Wednesday afternoon, with a cold front starTing to cross late. Showers and thunderstorms will develop in the warm sector Wednesday afternoon in advance of the cold front. A strong mid/upper level jet will help provide support for the thunderstorms. Additional support will be provided from a disturbance in advance of an approaching upper trof. The strength of afternoon thunderstorms will largely depend on the amount of heating and de-stabilization which occurs in the warm sector with greater sun leading to increased instability. Strong to possibly severe thunderstorms are possible Wednesday afternoon if enough instability can develop. CAPE values of 1000-2000 J/kg, with Downdraft CAPE values of 1000-1500 J/kg are expected Wednesday afternoon dependent on the degree of de-stabilization. The region remains in a Marginal Risk for severe thunderstorms Wednesday. Showers/thunderstorms will then end in the wake of the cold front Wednesday night. Rainfall totals tonight into Wednesday night will generally range from around 3/4 to 1.50 inches Downeast, with around 1/3 to 3/4 of an inch north. However, locally greater totals are possible particularly with any convection. This could lead to localized urban/poor-drainage flooding, particularly Downeast.

KEY MESSAGE 2...Dangerous Rip Currents and potentially High Surf along the Downeast coast Wednesday.

KEY MESSAGE 2 DESCRIPTION... Rough seas will occur along the Downeast coast Wednesday with large breaking waves from a long period southerly swell. A High Surf Advisory could be needed along the Downeast coast Wednesday dependent on how rapidly seas build.

On Thursday, seas will be about 2 feet lower as compared to Wednesday. That said, they will still be rather rough for this time of year, with 4-6 ft seas still mostly as a south swell with a fairly long period of around 9 seconds. So although seas will be a bit calmer, conditions along the coast could be hazardous for people recreating near the shore. Also, the weather Thursday will be quite a bit nicer than Wednesday, and this will bring more people outside and in potential harm's way.

KEY MESSAGE 3...Potential for a system moving in Monday/Tuesday, bringing some wetting rainfall.

KEY MESSAGE 3 DESCRIPTION... Quiet, dry weather from Thursday to Sunday with a warming trend. Then Monday/Tuesday, most models bring wet weather as a low pressure system moves northeast through the region. Exact track and timing of the low pressure system is uncertain, but in general, models favor rain at some point Monday/Tuesday, with a chance of thunderstorms too.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

00z TAF UPDATE... Tonight...Initially VFR across all terminals, lowering to MVFR then IFR/LIFR from south to north overnight as -RA and BR overspread the area. PROB30 for TSRA with brief IFR cigs/vsbys at KBGR and KBHB between 03Z and 07Z. S to SE winds generally 10 to 15 kts with gusts 20 to 25 kts. LLWS developing between 02Z and 04Z across all terminals, with S to SE winds 40 to 45 kts at 2kft.

Wednesday...LIFR/IFR cigs and vsbys early in the morning with lingering BR and VCSH. TEMPO 1/4SM FG at KBHB between 10Z and 13Z. Conditions will gradually improve to MVFR by early afternoon. Afternoon -SHRA with PROB30 for -TSRA and CB between 18Z and 23Z across northern terminals and KBGR. S to SW winds 10 to 15 kts gusting 20 to 25 kts. LLWS ending by 11Z-12Z north and 15Z south. Northern terminals and KBGR improving to VFR late in the TAF period.

Wednesday night...Variable conditions with strong to possibly severe thunderstorms possible during the evening, then with any patchy fog overnight. Otherwise, VFR/MVFR. Southwest/west winds 10 to 15 knots.

Thursday - Sunday...Mainly VFR. W wind gradually becoming S on Saturday/Sunday. Winds generally 5-10 kts, except W 10-15 kts with gusts to 25 kts during the day Thursday.

MARINE

The Small Craft Advisory is now in effect til 6 AM Thursday. Rain with isolated/scattered thunderstorms tonight. Showers along with isolated/scattered thunderstorms Wednesday into Wednesday evening. Areas of fog tonight into Wednesday night.

Winds relax to 15 kts or less Thursday morning, and wave heights 5-8 ft early Thursday fall below 5 feet by Friday. Little or no marine fog expected Thursday to Sunday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory until 6 AM EDT Thursday for ANZ050>052.