Severe Thunderstorm Warning 7, NWS Caribou, ME

Area Forecast Discussion
National Weather Service Caribou ME
551 AM EDT Wed Jun 17 2026

.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.

&&

DISCUSSION...AES/SM
AVIATION...AES/SM