Penobscot Bay Marine Forecast
|Tonight...S Winds Up To 10 Kt, Becoming Around 5 Kt After Midnight. Seas 1 Foot Or Less.|
|Fri...Se Winds Around 5 Kt, Becoming S In The Afternoon. Seas 1 Foot Or Less. Areas Of Fog. Vsby 1 To 3 Nm.|
|Fri Night...Sw Winds 5 To 10 Kt, Becoming W After Midnight. Seas 1 Foot Or Less. Areas Of Fog. Vsby 1 To 3 Nm.|
|Sat...Sw Winds 5 To 10 Kt. Seas 1 Foot Or Less. Areas Of Fog In The Morning With Vsby 1 To 3 Nm.|
|Sat Night...Sw Winds 5 To 10 Kt. Seas 1 Foot Or Less.|
|Sun...Sw Winds Around 5 Kt. Seas 1 Foot Or Less. A Chance Of Showers And Tstms. Some Tstms May Produce Gusty Winds.|
|Sun Night...W Winds Around 5 Kt. Seas 1 Foot Or Less. A Chance Of Showers. A Chance Of Tstms. Some Tstms May Produce Gusty Winds In The Evening.|
|Mon...Nw Winds Around 5 Kt. Seas 1 Foot Or Less.|
|Mon Night...Nw Winds Around 5 Kt. Seas 1 Foot Or Less.|
|Tue...W Winds Around 5 Kt. Seas 1 Foot Or Less.|
|Tue Night...W Winds Around 5 Kt. Seas 1 Foot Or Less. Winds And Seas Higher In And Near Tstms.|
|Area Forecast Discussion|
National Weather Service Gray ME
701pm EDT Thu July 18 2019
Synopsis: High pressure moves east tonight with a warm southerly wind beginning on Friday. A hot and humid air mass will begin building into the area. New Hampshire will feel the heat and humidity on Friday, while it spreads to Maine on Saturday. Very hot and humid conditions could lead to heat illness for those exposed to the heat. The heat and humidity lingers on Sunday before a cold front moves through and brings cooler and drier weather for next week.
Near Term - Until 6am Friday Morning
7pm Update...Just a few minor adjustments at this time, mainly to sky cover. Have updated skies based on latest trends in satellite imagery, with mostly cloudy skies over much of NH. Gradual clearing should be the trend through midnight but will likely hang on longer than previously forecast (except for southernmost zones where they will hang on much later). Otherwise, little change.
Previously... Stalled frontal boundary south of New England will keep low level moisture flirting with southern New Hampshire overnight as weak onshore flow continues. Hard to say how far inland this ocean stratus will penetrate but dry air tucking in from the north should limit northward progress so just thinking the three southern New Hampshire counties will be most likely to see clouds. Remainder of the forecast area will see variable high clouds. Lows will be fairly uniform across the area with readings bottoming out from 55 to 60
Short Term - 6am Friday Morning Through Friday Night
A warm front will push in from the west on Friday. Boundary layer winds will quickly switch into the southwest pushing any lingering low level moisture out to sea. May see a brief shower in northern zones in better dynamics as the warm front passes. Although the day will start with comfortable humidity levels...heat and humidity will build Friday afternoon with highs pushing 90 degrees in southern New Hampshire and ranging through the 80s elsewhere. Exception will be in the midcoast where southwest flow will hold temps in the 70s.
Along with the heat and humidity will come enough instability in western zones for afternoon and evening showers and thunderstorms mainly across western New Hampshire. Good uni- directional shear may produce some wind damage with stronger cells but Storm Prediction Center not highlighting the area in a convective outlook.
Nashua and Manchester briefly touch heat index of 95 but only for an hour in the case of Manchester. Considering the marginal situation will hold off on heat advisories in southern New Hampshire and will continue with heat watch for those areas for Saturday and Sunday.
Diurnal convection will die out Friday evening leaving just variable cloudiness overnight. Looking for a warm and very humid night with lows from the mid 60s north to the mid 70s south
Long Term - Saturday Through Thursday
While much of Maine misses out on the heat on Friday, that won't be the case for Saturday. With winds shifting to the west, the hot and humid air mass that has been plaguing the Midwest will move right in all the way to the coast. With the peak of the hot air over our area on Saturday, afternoon temperatures will soar into the mid to upper 90s. A few 100 degree readings are possible as well. Dewpoints begin the day in the low to mid 70s which will feel quite oppressive. However, models still indicating some drier air will mix down in the afternoon as the boundary layer extends up into the drier air aloft. The drying isn't as dramatic as was seen in the models yesterday, though, so dewpoints falling into the upper 60s to near 70 during the peak heating of the day seems appropriate. This still spells heat index values over 95 for most of the forecast area as well as values near or over 105 degrees in southeast New Hampshire. Have decided to maintain the Excessive Heat Watch and in fact expand it eastward slightly as the remains the potential for heat index values over 105 degrees. With the complication of dry air mixing down in the afternoon we were not confident enough to upgrade the Watch to a Warning just yet. However most of the area will likely need a Heat Advisory.
Some thunderstorms forming to our west Saturday afternoon may drift into the region during the evening. If so, it would primarily impact northern parts of the area. Otherwise it will be a warm and humid night with low temperatures in the low to mid 70s for most.
A cold front moves southeast toward the area on Sunday, but will take its time making it through the area. As a result we may actually have one more day of the oppressive heat and humidity and we may need additional Heat Advisories or a continued Excessive Heat Warning. As the front moves down into this humid air mass there is a chance of thunderstorms during the day on Sunday. With decent mid level wind flow and strong low level lapse rates, there will be a chance for these storms to become strong to severe if they occur. The front moves offshore Sunday night with any lingering storms ending during the evening. Drier air will be moving in so temperatures will be able to cool off into the 60s except for perhaps far southern areas where it may stay near 70 again.
The front settles south of New England on Monday with any waves tracking east along the front keeping their impacts over southern New England. The air mass behind this front is coming right out of the Arctic. If this were January we'd be talking about some bitter cold, but this time of year we will just be seeing some refreshing low humidity with temperatures in the 70s to low 80s for highs for the early part of next week.
For the most part it will be dry next week, but the northern stream trough axis shifts toward our area and could bring some showers or thunderstorms primarily in the afternoon. Models don't agree on what day to bring this through, but the potential exists as early as Tuesday
.AVIATION /00Z FRIDAY THROUGH TUESDAY/... Short Term: Areas of MVFR ceilings in southern New Hampshire overnight. VFR Friday through Friday night.
Long Term: VFR conditions expected as a hot and humid air mass moves into the area. Some thunderstorms are possible in northern areas Saturday evening and area wide on Sunday as a cold front moves through
Short Term: No flags as winds remain light over the waters through Friday night.
Long Term: Light southwest flow continues through Sunday when a cold front drops down from the northwest. This front drops south of the area and stalls south of Cape Cod through early next week
High temperatures this weekend will be hot but are currently forecast to stay below record levels at Concord and may approach the record at Portland on Saturday. The record highs are as follows:
JUL 19 CONCORD: 98 in 1977 PORTLAND: 95 in 2013
JULY 20 CONCORD: 101 in 1977 PORTLAND: 96 in 1949
July 21 CONCORD: 101 in 1977 PORTLAND: 99 in 1977
The Concord, NH ASOS remains out of service. At this time a return to service date is unknown. During the outage, TAFs will continue to be issued for Concord without amendments scheduled. Climate data for Concord will also be affected, although backup sources may be used to fill in data after the fact.
The Sugarloaf NWR transmitter is off the air until further notice. This will be an extended outage as the tower, which was severely damaged in a winter storm, is rebuilt.
NOAA Gray/Portland ME Office - Watches - Warnings - Advisories
ME...None. NH...Excessive Heat Watch from Saturday morning through Saturday evening for NHZ010-012>015. MARINE...None.