textproduct: Caribou

WHAT HAS CHANGED

- Precipitation chances were removed from most of our area Saturday with frontal convergence expected to focus west of our area.

- Temperatures have trended slightly warmer on Saturday night into Sunday AM, resulting in not as cold wind chills. Keeping the Extreme Cold Watch as is for now.

- Precipitation chances have increased slightly mid to late week with the potential of a storm system nearby.

KEY MESSAGES

1) Arctic cold front crosses the region Saturday with dangerous wind chills Saturday night into Sunday night. Below normal temperatures persist into Monday.

2) Calm air and clear skies is resulting in bitter cold temperatures early this morning, especially in the valleys.

3) Pattern turns favorable for a storm system nearby but a lot of uncertainty in operational and ensemble members.

DISCUSSION

KEY MESSAGE 1...Arctic cold front crosses the region Saturday with dangerous wind chills Saturday night into Sunday night. Below normal temperatures persist into Monday.

KEY MESSAGE 1 DESCRIPTION... Overall operational modeling and ensemble members have maintained consistent timing of the arctic front across the state Saturday PM into the evening. It is very moisture starved in our area as the weak surface low tracks deeply SE of southern New England with rapid development expected. The 500mb trof digs deeply to our south on Saturday with a 504dam low up over northern Quebec and a 513dam low diving south of Long Island. Temperatures will rapidly fall behind FROPA as this airmass is purely arctic.

Running the NOAA Hysplit Backward Trajectory model this airmass arriving at CAR & BGR originated from Siberia Russia on Jan 28th and stayed around the North Pole between Jan 29-31st. The cold air broke off and pushed south to Hudson Bay Canada then will be arriving into Maine Saturday night. This is very textbook with a strong negative AO (-3.5SD), positive PNA (+1SD) and weak negative neutral NAO. The weak negative neutral NAO gives confidence this arctic blast will be short lived at only 48-72hrs and we will return to seasonable conditions.

Saturday night temperatures will fall back into the -5F to +5F range from Eastern Aroostook to Penobscot Valley including Baxter SP area south to the Downeast Coast with the Downeast the best locations to remain on the positive side of 0F. Raised temperatures 1-3 degrees based on the latest NBM 4.3 and 5.0 probabilities. For the Moosehead Region into the North Woods modeling has warmed the air temperatures slightly in the last 1-2 cycles resulting in air temperatures into the -10F to -5F range. As low pressure deepens well south of Maine and high pressure in Quebec pushes in with the 500mb trof to our west gives us the best chance of a breezy night. Modeled soundings continue to indicate a well mixed boundary layer up 2kft to 950mb where winds are expected to be in the 25-35kt range. NBM operational winds/gusts continues to be low so opted to add in NBM90th percentile for wind speeds and increased wind gusts especially along the Longfellow Mtns. This remains consistent with NBM 4.3 and 5.0 QMD wind gusts probabilities of >25mph gusts in the 50-70% range in most of the CWA with probs of gusts >30mph in the 60-80% range along the Longfellows. The combination of gusty winds and cold temperatures will send wind chills pretty widespread -20F to -10F for the CWA. Wind chills ranging -35 to -25F across the North Woods and Moosehead Region will be the coldest spots. Given the decreased confidence reaching the -35F wind chill criteria for warning have opted to keep the Extreme Cold Watch for Northern and Central Piscataquis and Northern Somerset counties from 7PM Saturday through 10AM Sunday. It is increasingly likely these areas will be under and advisory instead of a warning. Outside of the watch area there may need to be a Cold Weather Advisory if wind chills reach -25F north and then -20F in southern zones which is criteria. The probabilities have fallen 5-10% in the last 2 cycles of the NBM suggesting we might be just sub advisory in more locations than previously expected. Either way still frigid!

Sunday will remain cold as the trof remains over the region and conditions remain breezy. The afternoon sun angle now peaks at 27 degrees off the horizon which is now helping modify the airmass a little bit. Highs into the single digits above zero to near 10F north and 10-15F for the rest of the CWA. Breezy NW winds 10-20mph with higher gusts will keep wind chills mainly below zero for most and around 0F at the coast. Sunday night yet another cold night with air temperatures pretty much CWA wide below zero with the coldest in the North Woods and St. John Valley. Sunday night into Monday there is another chance of Cold Weather Headlines with 40-50% probabilities of reaching advisory level criteria in portions of the northern 1/2 of the CWA.

KEY MESSAGE 2...Calm air and clear skies is resulting in bitter cold temperatures early this morning, especially in the valleys.

KEY MESSAGE 2 DESCRIPTION... The tranquil air and clear sky early this morning has resulted in radiational cooling allowing temperatures to drop to bitter cold levels. Calm air has resulted a big contrast in temperatures between the valleys, which are dropping to the teens below zero, and the higher elevations, down to the single digits below zero. Sunshine today will allow temperatures to recover to the mid teens north and the low 20s south.

KEY MESSAGE 3...Pattern turns favorable for a storm system nearby but a lot of uncertainty in operational and ensemble members.

KEY MESSAGE 3 DESCRIPTION... The latest ensemble forecasts for the AO are turning positive as the PNA goes negative and NAO turns neutral. Under weak La Nina conditions the transitional period of the subseasonal teleconnections typically brews a storm system. Given the AO going positive this favors the northern stream jet and southern jet shifting north over the CONUS into a more favorable position to develop a storm system off the New England coast. We are starting to see signs of this in the operational models, ensemble members and AI models. Since we are looking at a Wednesday to Friday timeframe there is a wide range of possibilities. The energy associated with this possibility is currently in the North Pacific southwest of Alaska. The AI ensembles are on the faster side with a possible system in the region Wed- Thu timeframe with non- AI ensembles in the Thu- Fri timeframe. Will continue to monitor the trend...NBM POPs did increase into the low end chance POPs during this timeframe and could not find a reason to change that for now.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

Today...VFR all sites. N wind less than 5 kt.

Tonight...VFR, possibly dropping to MVFR northern sites. N wind less than 5 kt.

Saturday...VFR/MVFR north and VFR south. N wind less than 5 kt early, increasing to 5 to 10 kt late.

Saturday night...VFR/MVFR north and VFR south. NW winds 10-15kt gusting 20-30kt. DRSN/BLSN possible at airfields. LLWS possible.

Sunday...VFR. NW winds 10-15kt gusting 20-25kt. DRSN/BLSN possible at airfields. LLWS possible.

Monday...VFR. NW winds 10-15kt gusting 20-25kt.

Tuesday...VFR. NW winds 5-15kt.

MARINE

Wind and seas will be below SCA today, tonight and Saturday morning. N winds will increase to SCA early Saturday afternoon, becoming NNE and approaching gale late Saturday afternoon. Seas 2 ft today and tonight, increasing to 3 to 4 ft late Saturday.

Winds will rapidly increase to N-NNW gales Saturday evening. A Gale Watch remains for all the Coastal Waters from 4PM EST Saturday through 1PM EST Sunday. Continuing to watch the trends on timing of the gales before going to a warning. N-NNW Gales are likely during this timeframe. N-NNW winds 20-30kt with gusts up to 40kt and seas 4-7ft. In addition to the Gales moderate freezing spray is expected from Saturday evening to Monday early afternoon. There remains a low end possibility for a brief period of heavy freezing spray Sunday morning but that potential continues to decrease. The Coastal Waters will be experiencing a prolonged period of hazardous conditions through Tuesday afternoon. Winds will relax back to SCA conditions later Sunday afternoon into the evening and expected to last through Tuesday afternoon/evening. Light to moderate freezing spray expected Monday through early Wednesday AM. Seas will generally be 2-4ft Monday through Wednesday. Tuesday night into Wednesday night winds/seas to be below SCA conditions. Beyond that into late next week there is a ton of uncertainty on the potential of a storm system near or south of the waters.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Extreme Cold Watch from Saturday evening through Sunday morning for MEZ003-004-010. MARINE...Gale Watch from Saturday afternoon through Sunday afternoon for ANZ050>052.