textproduct: Caribou

WHAT HAS CHANGED

- 11:27AM UPDATE...Have upgraded the Small Craft Advisory to a Gale Warning on Coastal Waters from Schoodic Point to Stonington out 25nm till 10PM this evening. The Gale Warning on the Waters 25-60nm has been extended till 10PM this evening. This is the match the better timing of the frontal passage using the CAMs. Additional updates to the forecast on land include the mentioning of heavy rain in any thunderstorms that develop this afternoon. Despite the significant cloud cover hi-res CAMs continue to show convective elements making it into the CWA this afternoon. Although thunderstorm coverage will mainly be isolated cannot rule out more storms, will need to watch the trends. Models continue to show significant rainfall where the occluded front tracks through the center of the CWA this afternoon into the early evening. Have increased rainfall totals to better represent the HRRR/RRFS/NAM trends along with the globals.

KEY MESSAGES

1) Widespread moderate to heavy rain today into tonight, with localized flooding possible. Gusty winds are also expected, especially within any strong showers and storms.

2) Showers Friday into the weekend along with a slight chance of afternoon thunderstorms Sunday.

DISCUSSION

KEY MESSAGE 1...Widespread moderate to heavy rain today into tonight. Localized flooding is possible, stemming from any training convection. Gusty winds are also expected, especially within any strong showers and storms.

KEY MESSAGE 1 DESCRIPTION... The next low pressure system will move in from the west through this morning, with rain beginning in our forecast area by mid morning and spreading across the entire region by early afternoon. The moisture for this system will be well supported, with model agreement that PWATs will approach 1.1 to 1.2 inches in the north and 1.3 to 1.4 inches Downeast through most of the event. For the northern half of the CWA, 1.2 inches is around the 90th percentile for KCAR PWAT climatology, which is 1.25 inches. For Downeast, 1.4 is around the 90th percentile for KGYX PWAT climatology, which is 1.44 inches. Exceedance of the climatological 90th percentile for PWATs is one factor to consider for the potential for efficient, heavy rainfall, and for this ingredient the forecast is considered marginal.

Long, skinny CAPE profiles are another ingredient that would favor flooding rain potential. That said, across the Downeast region, the marine layer presents a deep low level inversion that inhibits CAPE development, and there is little instability at all to work with. (There is, however, no shortage of shear, with 0-6 km bulk shear approaching 60 kts)

Should there be slow storm motion, this would be another ingredient to favor flooding rain potential. Alas, a 50 kt LLJ will be developing, and storms will be flying across the forecast area. This does not necessarily eliminate this ingredient from consideration, as storms could still train. Should strong showers and storms begin to train over the same area, this will increase the chance for flooding rain in that area, and is another check in the marginal box. WPC does have a marginal excessive rain outlook for our area.

The 50 kt LLJ will likely mix some momentum to the surface within moderate to heavy rainfall, leading to gusty winds which could occasionally reach 30 to 35 mph in strength, especially across higher terrain.

KEY MESSAGE 2...Showers Friday into the weekend along with a slight chance of afternoon thunderstorms Sunday.

KEY MESSAGE 2 DESCRIPTION... An upper level low will slowly cross the region Friday into the weekend while a series of disturbances move around the low. Cold air aloft will help increase diurnal instability. Unsettled conditions with a chance of showers will occur Friday through the weekend, with a slight chance of afternoon thunderstorms on Sunday. The better shower/thunderstorm chances should occur across northern areas. Another system approaches Monday night.

AVIATION /15Z THURSDAY THROUGH MONDAY/

Today - Tonight...VFR conditions will decrease towards MVFR/IFR through today as rain showers move in and cigs decrease. Gusty SE winds 10 to 15 kts with gusts 25 to 35 kts through this afternoon. Winds begin to decrease tonight, though 45 to 50 kts LLWS may enter in late as an inversion develops.

Friday...KBGR/KBHB and Downeast terminals improve to VFR through the day, while northern terminal cigs remain MVFR/IFR with lingering rain showers. SW winds slowly shifting W at 10 to 15 kts with gusts 20 to 25 kts.

Friday night...VFR/MVFR. Showers likely north. Southwest/west winds 10 to 15 knots.

Saturday...VFR/MVFR with a chance of showers. West/southwest winds 10 to 15 knots with gusts up to around 20 knots, becoming west/northwest.

Saturday night...VFR/MVFR. A slight chance of showers, mostly north. Some patchy fog is possible. Northwest winds 10 to 15 knots, becoming north/northwest 5 to 10 knots.

Sunday...VFR/MVFR with a chance of showers. Slight chance of an afternoon thunderstorm. West/northwest winds 5 to 10 knots, becoming variable.

Sunday night...VFR. Winds light and variable.

Monday...MVFR/IFR in heavier showers, with a chance of thunderstorms. South winds 5-10 knots, becoming northeast 5-10 knots.

MARINE

There is now a gale warning for the outer waters out to 60 NM for wind gusts to 35 kts. From shore out to 25 NM, wind gusts will remain in the 25 to 30 kt range, though a few gusts to 35 kts may be possible in any stronger showers or storms that cross these waters. Fog early this morning will dissipate today as widespread rain showers move in through the day and into this evening, before pushing east late tonight into Friday. Seas will build to 5 to 8 ft by Friday.

Small craft advisory conditions possible on the intra-coastal and coastal water Friday into Saturday, with wave heights between 5-7 ft and a few gusts to 25 kt. Conditions below small craft advisory levels Saturday night into Monday. A chance of showers Saturday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory until 8 AM EDT Friday for ANZ050-052. Gale Warning until 10 PM EDT this evening for ANZ051-080-081.