textproduct: Caribou

WHAT HAS CHANGED

- 550 AM Update: Adjustments made to the aviation section below with the 12z TAFs.

-Increased confidence in cool, showery conditions over the north Friday through the weekend.

KEY MESSAGES

1) Scattered showers and isolated thunderstorms in Northern Maine this afternoon.

2) Localized flooding is possible Thursday through Thursday night.

3) Below normal temperatures and showery conditions likely this weekend along with a few thunderstorms.

DISCUSSION

KEY MESSAGE 1...Scattered showers and isolated thunderstorms in Northern Maine this afternoon.

KEY MESSAGE 1 DESCRIPTION... A high CAPE, low shear environment is in place for the day today which will support diurnal shower and thunderstorm development. Most showers and storms will remain across the North Woods, though some may develop into the Central Highlands and through Central and Southern Aroostook county. CAPE values of around 500 to 1000 J/kg will help support vertical development of towering cu transitioning to showers and potentially thunderstorms. However, 0-6km bulk shear values may only be around 20 kts, limiting the longevity of any storms which develop. Additionally, though some mid level moisture will exist for this development, the 00z KCAR sounding showed that plenty of dry air exists as well which will limit fuel for any convection through the day.

KEY MESSAGE 2...Localized flooding is possible Thursday through Thursday night.

KEY MESSAGE 2 DESCRIPTION... The next low pressure system will move into the area from the southwest on Thursday, with rainfall moving into the Central Highlands and Bangor region through mid Thursday morning, then spreading across the rest of the forecast area through Thursday afternoon. Widespread wetting rain will continue into Thursday night, with at least an inch of rain expected for most of the forecast area. PWATs in excess of 1.2 inches combined with a marginal warm cloud layer of just under 10 kft could support efficient rainfall rates, especially with training heavier showers. Localized flooding is most likely in any areas where heavier rain showers train within the developing LLJ Thursday afternoon and evening.

The developing LLJ around 925 mb will approach 35 to 45 kts. These winds may get mixed down with the rain, resulting in gusts 30 to 35 mph possible.

Widespread rain showers will end over most of the area late Thursday night as a cold front crosses the CWA. Closer to the center of the occluding low pressure, the northern half of the forecast area could see continued rain showers through the day on Friday as well.

KEY MESSAGE 3...Below normal temperatures and showery conditions likely this weekend along with a few thunderstorms.

KEY MESSAGE 3 DESCRIPTION... Upper-level low pressure sticks around through much of the weekend which should contribute to cooler temperatures in the 60s, running around 5 to 10 degrees below normal, mainly in the north. In addition, cold air aloft and lift from shortwave energy rotating around the upper low should contribute to scattered showers and possibly a few thunderstorms over northern areas. Generally less confident on the thunderstorm threat due to weak instability and and low potential for heating.

AVIATION /09Z WEDNESDAY THROUGH SUNDAY/

Today - Tonight: VFR conditions will continue across all terminals through today and into the night tonight. S winds 5 to 10 kts with a few gusts to 20 kts this afternoon will become light and variable overnight. Slight chance for showers and isolated thunderstorms this afternoon, with the best chance being at KFVE. However, KCAR south through KHUL through KGNR have a slight chance to see these conditions briefly as well (15 percent chance).

Thursday-Thursday night: IFR/LIFR in locally heavy rain and fog. S-SE winds 10-15 kts with gusts up to 30 kts possible. LLWS possible at southern terminals.

Friday: Improvement to MVFR at southern terminals early Friday morning, then gradual improvement throughout the day. MVFR/IFR persists at northern terminals in rain showers. WSW winds 10-15 kts with gusts up to 25 kts.

Saturday-Sunday: MVFR/IFR in rain showers, especially at northern terminals. W/NW winds 10-15 kts Saturday, decreasing to 5-10 kts Sunday.

MARINE

Wind gusts should be 20 kts or less and seas 4 ft or less on all waters out to 60 NM through tonight. Winds and seas will increase Thursday through Thursday night. Gusts could approach 35 kts Thursday afternoon on the outer waters out to 60 NM, and a gale watch is in place for these zones. Elsewhere, gusts could reach 25 to 30 kts Thursday.

Seas peak at 6 to 9 ft Thursday night with max wind gusts 25-30 kts on the coastal and intracoastal waters and 30-35 kts on the outer waters. Marginal SCA conditions may persist on the coastal and intracoastal waters into Saturday. Below SCA conditions Sunday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Gale Watch from Thursday afternoon through Thursday evening for ANZ080-081.