textproduct: Caribou

WHAT HAS CHANGED

Issued Flood Watch for the North from 2pm Today through 8am Monday.

KEY MESSAGES

1) Locally heavy rainfall and severe thunderstorms possible into Monday

DISCUSSION

KEY MESSAGE 1... Locally heavy rainfall and severe thunderstorms possible into Monday

KEY MESSAGE 1 DESCRIPTION... With flash flood guidance as low as 1 inch in and hour and 2 inches in 6 hours, and with Convective Allowing Models showing potential for 1-2" of rainfall in scattered locations across the North in 1-3 hours from early afternoon into Monday morning across the North, have issued a Flood Watch for this area from 2pm Today through 8am Monday. Across Downeast Maine and the Bangor Penobscot Region, it looks like any heavier precipitation holds off until tonight. Also, it looks like convection could be more progressive/less likely to train, so confidence in flooding in this region is not as high at this time. Will continue to assess the flooding risk in this area, and its possible a flood watch could be issued for some or all of this area later today.

Occluding low pressure system moves in from the west. By this morning, warm front moves across the region, bringing in plenty of moisture. Pre-frontal troughing could help produce some morning showers across the northern areas, which could use up some of the instability in the northern region before the primary severe threat later in the afternoon. Anticipating partially to mostly cloudy skies during the day today, but frontal passage will provide enough lift for storm development.

In terms of the severe threat, there is a plethora of favorable parameters to hint at severe storm development. During the afternoon period, elevated levels of CAPE >1000-1500 J/kg, low- level lapse rates 8-9 C/km, PWATs roughly 1.25 - 1.50 inches and a couple hundred J of DCAPE point towards the chance for severe thunderstorms that could produce heavy rain and gusty winds. There is a chance for some small hail to develop with these storms. There is a non-zero chance for tornado development as well, with low LCL heights, and plenty of shear. Highest areas of concern are the Central Highlands and Upper Penobscot Valley. Additionally, periods of heavy rainfall on already moist soil could cause some hydro concerns, leading to some potential flooding in localized areas. For reference, 1-1.5 inches of rainfall within 1 hour, in regions north of Bangor, could cause flooding. Make sure to have multiple ways to get warning information, and stay weather aware!

AVIATION /12Z SUNDAY THROUGH THURSDAY/

Today and tonight...Early IFR/LIFR due to low cigs/vsby will trend generally VFR/MVFR today, periods of rain showers and thunderstorms at KFVE/KCAR/KPQI/KHUL. Otherwise, generally VFR at KBGR and KBHB. Thunderstorms at northern terminals could bring periods of heavy rain, gusty winds, and lightning. LLWS starts late tonight at KBGR/KBHB. Ran showers continue into tonight, but thunderstorm potential decreases past midnight. Expecting a return to IFR/LIFR conditions due to cigs/vsby.

Monday...MVFR or lower possible Monday morning, with some morning fog. Also isolated thunderstorms possible at Downeast terminals Monday morning. Potential for isolated thunder at KFVE and KCAR Monday evening. S winds 5-10KT shifting to W winds, with gusts 15-20KT.

Monday night-Wednesday...VFR. WSW G15-20KT possible Tuesday afternoon.

Thursday...MVFR/IFR in rain showers and possible TS. SE winds 10-15 kts.

MARINE

Winds and seas ramp up to Small Craft criteria tonight, over all waters. Fog is expected to develop overnight, reducing visibility. Rain showers possible Monday. Winds from the S today into Monday.

Conditions drop below small craft levels on Monday afternoon and remain that way into the middle of next week.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Flood Watch from 2 PM EDT this afternoon through Monday morning for MEZ001>006-010-031. MARINE...Small Craft Advisory from 8 PM this evening to 2 PM EDT Monday for ANZ050-051. Small Craft Advisory from 8 PM this evening to 8 AM EDT Monday for ANZ052.