textproduct: Caribou

WHAT HAS CHANGED

Update for 12z Aviation section

-Increased pops on Saturday ahead of cold front

KEY MESSAGES

1) A strong cold front will bring rain and snow showers and strong gusty winds Saturday afternoon followed by falling temperatures Saturday evening. Wind impacts Saturday afternoon and icing on road surfaces Saturday night are possible with the front.

2) Bitter cold Arctic air will surge into the region Saturday night into Sunday bringing frigid wind chills and the risk of hypothermia.

3) Snow will accumulate 1-3 inches over Downeast this afternoon, impacting the evening commute.

DISCUSSION

KEY MESSAGE 1...A strong cold front will bring rain and snow showers and strong gusty winds Saturday afternoon followed by falling temperatures Saturday evening. Wind impacts Saturday afternoon and icing on road surfaces Saturday night are possible with the front.

KEY MESSAGE 1 DESCRIPTION... Low pressure tracking into Central Quebec combined with high pressure dropping south into the Plains will push a strong Arctic cold front toward the area on Saturday. A tight gradient between the approaching cold front and high pressure sliding off to the east will bring strong gusty south winds on Saturday. As the front pushes in Saturday afternoon, some rain and wet snow showers will push into the area, mainly across central and northern areas. Forecast soundings are showing a brief period of steep lapse rates up to 6K ft late Saturday afternoon. A tight SSW gradient aligned deep in the atmosphere will result in the potential for strong wind gusts as the front pushes in late in the day causing deeper mixing and pulling down some of the higher winds from aloft.

The cold front will cross the area early Saturday evening followed by falling temperatures as Arctic air surges in. Any dampness on the roads caused either by the rain or wet snow ahead of the front or streamers of melting snow left over from the mild day on Saturday will freeze and result in the potential for icy patches Saturday night. Gusty winds will likely continue Saturday night as the colder air surges in and some mixing continues to take place.

KEY MESSAGE 2...Bitter cold Arctic air will surge into the region Saturday night into Sunday bringing frigid wind chills and the risk of hypothermia.

KEY MESSAGE 2 DESCRIPTION... Arctic air will surge into the area behind the cold front Saturday night into Sunday. By Sunday morning temperatures will have dropped to around zero in the northwest and 20 along the coast, only to rise into the mid teens north and near 30 Downeast Sunday afternoon. The coldest temperatures will come Sunday night as high pressure begins to build over the region. Lows by Monday morning will range from the teens below in the northwest to near zero by the coast. A light westerly breeze Monday morning will combine with the frigid temperatures to produce wind chills down to the mid 20s below across the north Sunday morning and the low teens below over parts of Downeast. This will be followed by highs Monday from near 10 over the far north to the upper teens by the coast which will be over 15 degrees below normal.

KEY MESSAGE 3...Snow will accumulate 1-3 inches over Downeast this afternoon, impacting the evening commute.

KEY MESSAGE 3 DESCRIPTION... Low pressure system currently north of Lake Superior will continue tracking toward the region this morning. Ridge axis currently over the CWA will keep snow at bay until around 15z this morning with warm front moving in. Overrunning snow will overspread the entire region by 18z as a weak triple point begins to develop. This will increase warm air advection along the shoreline and outer islands where rain may briefly mix in, and cut down on snow accumulations. Synoptic lift will be enhanced by convergence with one-half to one inch per hour rates around the time of the evening commute along the coast. This will briefly reduce visibilities and likely lead to slick travel.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

Today...VFR at terminals into the late morning hours before MVFR restrictions move in with light snow. Conditions quickly deteriorate to IFR with BHB the most likely site to see LIFR conditions this afternoon. LLWS at HUL, BGR and BHB this afternoon and evening. SSE wind 5-15kts.

Tonight...MVFR/IFR in snow through the evening hours with Downeast terminals improving to MVFR late while Aroostook terminals see MVFR tempo IFR into Thursday morning. SW wind 5kts.

Thursday...VFR south with MVFR north. Cannot rule out brief IFR at northern Aroostook terminals in any heavy snow showers. SW 5-15kts.

Thursday night and Friday...VFR. W wind around 5 kt.

Friday night...VFR dropping to IFR south late, and dropping to MVFR over the north late. S wind 5 kt increasing to 5 to 10 kt late.

Saturday...IFR except in a few midday breaks. S wind 10 kt increasing to 15 kt with higher gusts. SW wind shear at 2K ft likely.

Saturday night...IFR to MVFR south. MVFR improving to VFR north. W wind 5 to 10 kt.

Sunday...VFR. NW wind around 10 kt.

MARINE

South winds increase ahead of developing low pressure with gusts to small craft levels this morning. The outer waters may briefly see a few gusts to gale force this afternoon but overall expecting steady small craft level winds. Seas will increase above 5ft this afternoon and will remain elevated over the outer waters through Thursday, while diminishing over the intracoastal zone this evening.

A SCA will be needed late Friday night into Saturday evening for S winds gusting up to 30 kt. A SCA and possibly a gale will likely be needed late Sunday through Sunday night for NW winds gusting up to 30 to 35 kt. Moderate freezing spray is likely Sunday night into Monday morning. Seas 5 ft Thursday night dropping to 4 ft Friday, then rising to 5 ft Friday night and 7 ft on Saturday in response to the southerly. Seas dropping back to 4 ft by early Sunday morning.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory until 7 PM EST Thursday for ANZ050-051. Small Craft Advisory until 7 PM EST this evening for ANZ052.