textproduct: Caribou

WHAT HAS CHANGED

-Issued coastal flood statement for tonights and Tuesday mornings high tide.

-Wind advisory issued for northern Washington, central Penobscot, and southeast Aroostook Counties

-Slight increases in winds tonight through Tuesday

-Decrease in rainfall amounts across northern Maine

KEY MESSAGES

1) Strong to damaging winds are likely along the Downeast coast and interior Downeast areas, including the Bangor region, tonight into early Tuesday morning. Gusty winds are possible across the remainder of the forecast area through Tuesday. Scattered to widespread power outages are possible across Downeast areas, including the Bangor region. Isolated power outages are possible across the remainder of the forecast area.

2) Snowmelt and 1 to 3 inches of rain through Tuesday morning may lead to ice jams and poor drainage flooding, mainly south of Baxter State Park and Houlton.

3) Strong southerly winds will generate high seas which should cause minor overwash and possibly localized beach erosion with the high tides tonight and Tuesday morning.

4) A series of weak systems are forecast to pass near the area from late Thursday through Monday. These could bring light to possibly moderate snow to the region, possibly impacting travel.

DISCUSSION

KEY MESSAGE 1... Strong to damaging winds are likely along the Downeast coast and interior Downeast areas, including the Bangor region, tonight into early Tuesday morning. Gusty winds are possible across the remainder of the forecast area through Tuesday. Scattered to widespread power outages are possible across Downeast areas, including the Bangor region. Isolated power outages are possible across the remainder of the forecast area.

KEY MESSAGE 1 DESCRIPTION... Enhanced shortwave energy will round the base of an upper level trough over the Great Lakes this evening, becoming negatively tilted and leading to an already strong 980mb low rapidly intensifying overnight to below 960mb by Tuesday morning across Quebec. This added energy will send a secondary surge of southerly winds with an intensifying low level jet (LLJ), especially after 3z. The latest projections for this low level jet are generally between 90 and 100 kts at peak intensity below 850mb. Other local rule of thumbs based on local research easily exceed warning thresholds for the coast. Similar events have produced scattered to widespread power outages and tree damage across Downeast Maine. A High Wind Warning is in effect for all of the Bangor area and Downeast Maine, where wind gusts to around 60mph are forecast. Thawing, wet ground may further exacerbate tree damage. A Wind Advisory has been issued for areas just to the north along I-95 through southeast Aroostook County, where wind gusts to 50 mph are possible late tonight. Wind gusts decrease with northern extent as snow cover increases low level stability and decreases the gust factor. However, a few stronger gusts are possible around the time of a strong cold frontal passage between 12z and 15z Tuesday morning. A squall line is possible across the North Woods with this front, but dynamics will become less favorable as the front moves east for maintenance of the squall. As the low intensifies during the day Tuesday northern areas will still remain in a strong pressure gradient with steepening low level lapse rates becoming dry adiabatic through 850mb. Wind gusts across far northern areas may approach advisory levels again during the day Tuesday, and a few additional power outages are possible.

KEY MESSAGE 2...Snowmelt and 1 to 3 inches of rain through Tuesday morning may lead to ice jams and poor drainage flooding, mainly south of Baxter State Park and Houlton.

KEY MESSAGE 2 DESCRIPTION... A Flood Watch is in effect from today into Tuesday for the Downeast, Bangor Region and into the Central Highlands including Southern Aroostook County. This is due to the threat of excessive runoff driven by heavy rain and rapid snowmelt. Additionally, there is a localized elevated risk for ice jams in the Downeast, Penobscot, Piscataquis, Mattawamkeag and Meduxnekeag river basins. An anomalously moist airmass with PWATs exceeding 350 percent of normal will interact with a ripened snowpack, setting the stage for potential hydrological impacts. Confidence is high for 1 to 2 inches of widespread rainfall in the Central Highlands to Downeast Maine, with some ensemble models highlighting the Route 9 (The Airline) corridor and south upslope of the Longfellow Mtns getting 2-3 inches of rain.

Initially, cold air damming in the Central Highlands and Northern Maine will limit snowmelt through this evening. However, this cold layer will erode tonight as a powerful 70-100 knot low-level jet ushers in a massive moisture surge. Precipitable water (PWAT) values are forecast between 1.20 and 1.40 inches near the 99th percentile for mid-March heavily favoring intense rainfall rates. This late-today surge of heavy rain will provide the primary catalyst needed to rapidly flush water out of the snowpack. We expect a snowmelt water loss of 1 to 2 inches to occur in a condensed 6 to 12-hour window between this evening and early Tuesday morning.

The coinciding of peak rainfall rates with rapid snowmelt will lead to swift rises on smaller streams and rivers. While mainstream rivers currently have ample channel capacity due to lingering drought conditions, confined mountain channels and small streams could easily be overwhelmed, resulting in localized minor flooding. The latest forecast on the Piscataquis River in Dover-Foxcroft is approaching action stage. Any additional water from snowmelt could lead this river to approach flood stage. Latest GEFS and HEFS ensembles give DOVM1 gage less than a 5 percent or less chance of flooding while the NAEFS has a 30 percent chance. These probabilities have decreased with the latest update due to slightly less rain expected to fall. NAEFS is still responding to the higher potential of runoff and heavier rainfall totals. Furthermore, a deep frost will severely limit soil infiltration; the sheer volume of runoff is expected to overwhelm culverts, low-lying areas, and low-water crossings, likely leading to urban street flooding and drainage issues across the southern half of the area. Significantly less rainfall is expected north of Baxter State Park, with around a half inch to one inch, limiting flood potential. However, minor poor drainage issues are still possible.

KEY MESSAGE 3...Strong southerly winds will generate high seas which should cause minor overwash and possibly localized beach erosion with the high tides tonight and Tuesday morning.

KEY MESSAGE 3 DESCRIPTION... High tide tonight is around 10 PM and the high tide on Tuesday morning is around 1030AM. The strongest winds are expected near the time of low tide tonight, 4-430am. As a result, should escape the worst with respect to coastal impacts with this storm. Most guidance now only suggests some minor overwash with limited minor beach erosion. As a result have issued a Coastal Flood Statement covering the high tides tonight and Tuesday morning.

Current total water level forecasts are for levels less than the forecast high tides later this week. With that said, the forecast guidance is currently running around 1 ft too low. If the error in guidance increases to over 2 ft, then its possible to see minor coastal flooding, especially during the Tuesday morning high tide. We will continue to monitor the performance of forecast guidance, and make appropriate adjustments to the forecast and headlines as required.

KEY MESSAGE 4...A series of weak systems are forecast to pass near the area from late Thursday through Monday. These could bring light to possibly moderate snow to the region, possibly impacting travel.

KEY MESSAGE 4 DESCRIPTION... The models all agree we will be in an active pattern from Thursday-Monday of next week. At least 3 to possibly 4 northern stream systems are progged to pass near the region during this time frame. However the models differ on the timing and impact with each system. They do suggest that each storm might be a bit stronger than the one before it. At this time the most likely solution is a light to moderate solution with each system, if each system brings precipitation at all. The storm which could have the most impact is the one for early next week (still uncertain as to if it will be on Sunday or Monday - or maybe both days). There is some chance that the northern stream energy could phase to some degree with southern stream energy and create a stronger system. This is indicated in a minority of guidance at this point.

As confidence is gained in the timing/strength/impacts with each system, we will split them out from this key message and address separately.

AVIATION /18Z MONDAY THROUGH SATURDAY/

IFR/LIFR through tonight with rain, moderate to heavy at times mainly after 0z, and LLWS. Strong southerly wind gusts are expected, especially from HUL south with peak gusts to 50 kts possible at BGR and BHB late tonight.

Conditions rapidly improve to VFR between 13z and 15z. Winds shift WSW, increasing over northern terminals with gusts to 35 kts, and decreasing over southern terminals with gusts to 30 kts expected through the day.

Tuesday night: VFR. W winds 5 to 10 kts with gusts to 20 kts.

Wednesday-Wednesday night: VFR. W winds G15KT possible Wednesday.

Thursday...Low chance of MVFR late. SE winds G15-20KT possible.

Thursday night-Friday...MVFR or lower possible. S-SE winds G15-20KT possible.

Friday night-Saturday...MVFR or lower possible. LLWS possible Friday night. NW winds G20-30KT possible Saturday.

Note: There should be some gap between the system for Thursday night/Friday and the one for Friday night/Saturday.

MARINE

Gale force winds will increase towards storm force tonight with gusts around 50 kts expected. Seas will increase to 15 to 20 feet. Fog and periods of moderate to heavy rain will reduce visibility. Isolated thunderstorms are also possible. Visibility, winds, and seas improve on Tuesday, but winds will remain at Gale force into Tuesday night before decreasing towards small craft advisory levels towards early Wednesday morning. Light freezing spray develops later Tuesday night.

SCA conditions likely on all waters Wednesday, with those conditions possibly lingering into Wednesday night on the coastal ocean waters. All waters should see sub-SCA conditions on Thursday. SCA conditions should then return to the coastal ocean waters Thursday night and the intra-coastal waters by Friday night. Gale conditions are then probable on the coastal ocean waters and possible on the intra-coastal waters by late Saturday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Flood Watch from 8 PM EDT this evening through Tuesday afternoon for MEZ005-006-010-011-015>017-029>032. Wind Advisory from 8 PM this evening to 10 AM EDT Tuesday for MEZ006-011-032. High Wind Warning from 8 PM this evening to 10 AM EDT Tuesday for MEZ015>017-029-030. MARINE...Storm Warning from 8 PM this evening to 8 AM EDT Tuesday for ANZ050>052.