textproduct: Caribou

WHAT HAS CHANGED

-Cancelled the remaining winter weather advisories

-Updated aviation section to reflect 0Z TAFs

previous -Extended Small Craft Advisory on all waters until Noon on Sunday.

-Increased confidence in strong storm Monday - Tuesday morning, with flooding threat and strong winds.

KEY MESSAGES

1) Wintry mix late Sunday night into early Monday morning across the North could impact the Monday morning commute.

2) A strong storm Monday into Tuesday will bring high winds and heavy rain, creating potential for scattered power outages and flooding.

3) Strong winds will generate high seas which could lead to wave runup and coastal flooding impacts, particularly if timing lines up with tidal surges.

DISCUSSION

KEY MESSAGE 1... Wintry mix late Sunday night into early Monday morning across the North could impact the Monday morning commute.

KEY MESSAGE 1 DESCRIPTION... The approach of a surface to 850 mb warm front and some weak vorticity advection at 700 mb could bring some light snow changing to a wintry mix, mainly across the North from Sunday night, with most precipitation falling after midnight, into early Monday morning. With a strong low to the west and a well defined ridge shifting east of the area, the forecast area will be in the prime synoptic location for the development of cold air damming. Strong 850 mb SW winds will advect warm air aloft while SE winds near the surface act to trap the previously cooler air to the Longfellows. What is in our favor with this system is the previous air mass is not arctic in nature, and will not be quite cold enough to sustain the CAD setup, becoming easily eroded into the day on Monday. Still, this pattern may result in a couple hours of freezing rain and/or sleet due to a strong surface inversion ending in a warm nose aloft.

Could see an inch or snow and up to around a tenth of an inch of ice north of the Bangor and Interior Downeast regions. This could impact the Monday morning commute with potentially slick surfaces.

KEY MESSAGE 2... A strong storm Monday into Tuesday will bring high winds and heavy rain, creating potential for scattered power outages and flooding.

KEY MESSAGE 2 DESCRIPTION... A strong occluding low pressure system will continue to approach from the west on Monday, with the forecast area in the warm sector Monday into Monday night prior to a strong frontal passage late Monday night into Tuesday morning.

Rain: - Deep moisture will advect into the forecast area on Monday with southerly flow and a strengthening LLJ. PWATs could surge towards well over 1 inch by Monday night with this event, which is 5 standard deviations above normal. To put this extreme moisture surge in perspective, the daily record 00z March 17 PWAT sample from KCAR is 0.83 inches, with forecast PWATs potentially being half an inch of additional moisture into a relatively cool air mass. With strong forcing spanning from the approaching low pressure system, this will likely result in moderate to heavy rainfall across the forecast area, with highest precip totals being across the Downeast region, where storm total rain amounts could exceed 2 inches.

Hydro: - Combined with warm temperatures lifting into the 50s through this time, the Downeast snow pack will quickly melt. All this water and snow melt could result urban and small stream flooding, especially Downeast. The snow pack in the north is better able to absorb the rain, and expected rain totals are less in the northern half of the forecast area. However, rain combined with what snow melt does occur in the north could also lead to localized ponding. Ice rot is likely in the north, while ice movement is quite possible Downeast, such as along the Penobscot.

Winds: - The strong LLJ projected with this system could reach 3 to 4 standard deviations above normal for 850 mb, and could see sustained winds as strong as 70 kts at this level. Rain Monday afternoon through Monday night will mix these higher winds towards the surface, with gusts reaching 35 to 45 mph. The strongest gusts could convectively occur along the FROPA early Tuesday morning, with an extra source of forcing and tightening of the pressure gradient. Strong southerly winds combined with the thawing ground could result in scattered power outages.

KEY MESSAGE 3... Strong winds will generate high seas which could lead to wave runup and coastal flooding impacts, particularly if timing lines up with tidal surges.

KEY MESSAGE 3 DESCRIPTION... Low level jet looks to kick in on Monday morning between 55-70kts over the waters. As pressure gradient tightens, sfc winds range from 30-35 kts Monday afternoon with an increase in sustained speeds between 35-40kts on Monday night. These will gradually shift toward the southwest Tuesday morning and drop back down toward 30kts on Tuesday afternoon.

High tide times will be around 9:30 am Monday morning, 10 pm Monday night and 10:30 am Tuesday morning. Winds, seas and storm surge will be gradually increasing around the time of high tide on Monday morning with wave heights near the shoreline between 4-8 feet. At the next high tide, storm surge will be increasing but not at it/s max. Probabilistic storm surge (PETSS) ranges from 0.8 to 1.3 feet during this timeframe with the PETSS50 around 1.0 feet. As it stands now, total water level is being run on a storm surge of between 0.5 to 0.8 feet so may see water levels go up as we get more confident on the surge, and an increase on coastal flood potential.

Storm surge looks to be maximized between the high and low tide on Monday night. Wave heights progged to range from 12-16 feet along the shoreline with periods of 9-10 seconds. Any minor adjustment to storm surge, seas and southerly wind gusts will make the difference between overwash on exposed coastal roads and significant coastal flooding. Will keep an eye on the potential over the coming days.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

Tonight...KFVE/KCAR/KPQI/KHUL: MVFR with occasional IFR in scattered snow showers early, becoming VFR after 07Z. NW to N wind 5 to 10 kt.

KBGR/KBHB: VFR, except brief MVFR or lower possible vcnty KBGR 02z-05z. NW to N wind 5 to 10 kt.

Sunday...VFR all terminals. N to NW wind 5 to 10 kt becoming S in the afternoon

Sunday night...Becoming MVFR or lower at southern terminals and IFR or lower at northern terminals. SE winds G20-25KT possible at northern terminals and LLWS likely at southern terminals after midnight.

Mon - Tues morning: IFR/LIFR, with VLIFR at times, particularly at KBGR/KBHB. Locally heavy rain probable, -TSRA possible. LLWS likely. SE winds 15 to 20 kts gusting 25 to 30 kts, with brief gusts 40 to 45 kts possible in any stronger convection Tuesday morning.

Tue afternoon: Becoming VFR. WSW winds 10 to 15 kts gusting 25 to 30 kts.

Tue night - Wed: VFR. W winds 10 to 15 kts gusting to 20 kts.

Wed night - Thurs: VFR early, becoming MVFR particularly at northern terminals in -SN. Winds light and variable shifting S at around 10 kts.

MARINE

SCA conditions should last through Sunday morning, so have extended the SCA on all waters through then. We could then see a lull with sub-SCA conditions Sunday afternoon and evening, before SCA conditions return to all waters late Sunday night, with gales possible late.

Strong gale conditions are likely Monday through Tuesday, with highest winds overnight Monday night that could approach storm strength. Seas 6 to 9 ft on Monday will increase into Monday night, becoming 13 to 20 ft by Tuesday morning. Winds and seas will then gradually improve through the middle of the week. Rain, heavy at times, Monday through Monday night, with lightning possible.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory until noon EDT Sunday for ANZ050>052.