textproduct: Caribou

WHAT HAS CHANGED

- Lowered temperatures and dew points a couple degrees tonight into Wednesday AM to account for wet bulb process at precipitation start time.

- Raised QPF from previous forecast due to better agreement on track of the low closer to the Downeast Coast.

KEY MESSAGES

1) Wet snow likely tonight into Wednesday AM for the Central Highlands, Bangor Region and Downeast Coast. Minor travel impacts possible mainly between 8PM and 6AM.

2) Light snow possible Thursday and Friday with some minor travel difficulties possible.

3) Warming trend and above normal temperatures for the weekend along with the potential for a wintry mix changing to rain.

DISCUSSION

KEY MESSAGE 1...Wet snow likely tonight into Wednesday AM for the Central Highlands, Bangor Region and Downeast Coast. Minor travel impacts possible mainly between 8PM and 6AM.

KEY MESSAGE 1 DESCRIPTION... Later today a weak open 500mb shortwave will track east out of the Great Lakes towards New England. Weak upper level divergence over Southern New England develops as the northern stream shortwave trough partially phases with the subtropical jet. This will give way to surface convergence and allow a surface low to develop near Boston this evening. Model guidance remains in rather good agreement of a surface low track over the northern part of the Gulf of Maine from Boston area to Digby, Nova Scotia area. There is decent agreement for about a quarter to third of an inch of QPF across Downeast Maine except potentially up to 0.5 at the shoreline falling mainly as all snow. Will see the potential of some rain mixing in on MDI and other islands but better agreement that the Washington County coast remains all snow. This will be a heavy, wet snow with snow ratios between 8 and 11 to 1 anticipated, producing roughly 2 to 4 inches of snow. There remains some uncertainty with how quickly the low deepens, and there is potential for a stronger low that could bring slightly more QPF northward. ECMWF deepens the low faster in the Gulf of Maine with slightly more improved upper level divergence with the phasing. GFS deepens the low but too late while the RRFS is one of the weaker but also too far south models.

What this comes down too...is we cannot rule out isolated locations potentially seeing advisory level snow amounts of 4-5 inches. HREF probabilities remain at about a 20 to 30 percent chance of at least 4 inches of snow Downeast while NBM probabilities have increased to 30 to 45 percent chance. This means there remains a chance that advisories may be needed with the forecast package update this afternoon if additionally higher QPF looks likely. Overall the forecast snow totals remain good with 1-3 inches for the Central Highlands, Northern Washington County and Bangor Region. Looking at 2-4 inches for interior Downeast along the Airline (Route 9) east to Passamaquoddy Bay. For the Route 1 area of Coastal Hancock to Washington County to the shoreline cannot rule out those isolated higher numbers but generally 2-4 inches here as well.

In terms of impacts...expecting slippery travel mainly from 8PM this evening through 6AM Wednesday AM. Winds will be light so not expecting heavy wet snow to impact the tree limbs. Snow covered and slushy roads are likely for the Wednesday morning commute, especially early on before temperatures warm well above freezing during the day Wednesday. Expect a lot of melting Wednesday as temperatures soar into the 40s.

KEY MESSAGE 2...Light snow possible Thursday and Friday with some minor travel difficulties possible.

KEY MESSAGE 2 DESCRIPTION... Two potential shots of light snow during this period. Cold front sinks down from the north Wednesday night through early Thursday. Some light snow is possible, mainly across far northern areas with this feature, as the front crosses the region. Some minor travel difficulties are possible for the Thursday morning commute, mainly affecting the St. John valley region.

Another system could bring some snow to the region Thursday night and Friday. Confidence is below average with regard to this system. It is possible that the strong high to the north across Quebec could suppress this system to our south. The best chances of seeing any snowfall with this system would be across Downeast areas, particularly the coastal region.

KEY MESSAGE 3...Warming trend and above normal temperatures for the weekend along with the potential for a wintry mix changing to rain.

KEY MESSAGE 3 DESCRIPTION... Temperatures both Saturday and Sunday are expected to surpass the 40 degree mark across the region with the passage of a warm front. Some snow or wintry mix is possible with the passage of the warm front later Friday night into Saturday. By Saturday afternoon, southerly winds will transport much warmer air across the entire forecast, with precipitation changing to all rain. At this point, we are not expecting significant rainfall. But the combination of the warm temperatures and rainfall will lead to some snowmelt. Some places mainly in southern portions of the area possibly losing all or nearly all of their snowpack. The potential for river, lake/pond ice decay/rot is also there, especially Downeast. We don't expect river ice to flush out Downeast though, and in the north, the river ice should hold completely through the weekend.

AVIATION /06Z TUESDAY THROUGH SATURDAY/

This Morning before 12z...Northern Terms LLWS likely. For all terms SKC-FEW250. Light and variable winds becoming S-SW around 5kt.

Today...VFR. SCT-BKN cigs developing this afternoon. S-SW winds 10-15kt gusting up to 25kt.

Tonight...IFR/LIFR southern terms with -SN. Brief RASN mix at BHB possible but mainly -SN. S winds around 5-10kt. VFR/MVFR northern terms with VCSH/-SHSN possible. Best chance of MVFR at HUL with -SN. S winds around 5-10kt.

Wednesday...Becoming MVFR/VFR SCT-BKN cigs. Winds shift W in the AM. W winds 5-15kt with gusts up to 20kt possible.

Wednesday night...VFR, except MVFR or lower at the Aroostook terminals in -SN after midnight.

Thursday...MVFR or lower at the Aroostook terminals in -SN, VFR elsewhere.

Thursday night and Friday...VFR north, but low chance of MVFR or lower in -SN at KBGR/KBHB.

Saturday...MVFR or lower possible. Wintry mix to rain.

MARINE

Small Craft Advisory in effect from 7AM this morning till 1AM Wednesday for all of the Intra-Coastal and Coastal Waters. SW winds 15-25kt with gusts up to 30kt and seas 3-6ft. Tonight rain and snow develops with vsby less than 1nm at times. Winds shift NW tonight and fall below SCA conditions. Precip will end and vsby recover early Wednesday AM. SW winds tomorrow generally less than 20kt and seas 3-5ft. Winds/seas are expected to remain below SCA levels Wednesday night and then increase to SCA levels Thursday into the weekend.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory from 7 AM this morning to 1 AM EST Wednesday for ANZ050>052.