Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
518 FXUS61 KGYX 060340 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1140 PM EDT Fri Jul 5 2024 .SYNOPSIS... Scattered thunderstorms move into the region this evening with storms becoming more widespread by Saturday morning. Some patchy dense fog is also possible, especially along the coast through tomorrow morning. Scattered thunderstorms move through ahead of a cold front tomorrow afternoon, with the front moving through tomorrow night and Sunday. High pressure builds in by early in the week, with a tranquil Monday and Tuesday. More storms are possible by Tuesday night as the next cold front approaches. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 1130pm Update...Spread of showers has decreased, and will likely be hit or miss for much of the night. Spent some time looking at Saturday. There is some strong storm potential as well as renewed threat for flooding due to training heavy rain. Usual players like 40kt of 0-6km shear, above avg PWATs, and energetic low level lapse rates will be in the region. But so will the other team of uncertainties like sluggish mid level lapse rates, extent of surface instability, and low level shear. Not too much gained confidence in the 00z suite of CAMs at this time, lots of variability thus time/location windows remain wide. I`d say there has been a trend towards more available CAPE, but mid level lapse rates remain squarely 4-5 c/km. So just how tall or vigorous storms get feels capped. Will have low LCLs and low level shear showing a curved hodograph. So some rotation in storms can`t be ruled out in mostly central and southern NH. Given tall/skinny CAPE, PWATs around 2", and warm cloud depth of > 10kft, any prolonged training convection should be watched for the chance for localized flooding. Could see some swaths of 2"+ where this occurs. The good news is dry antecedent conditions that should stave off too widespread of a FF risk. 9pm Update...Vertical extent of showers and storms should be limited overnight as surface instability tapers this evening. Decreased coverage of thunder tonight as well as tried to hone in on more specific areas of showers. This mainly revolves around area of rain making its way north out of southern New England. Still some elevated instability for the night time hours so some of these showers could have moderate rates with them as it works along the coast overnight. With increasing clouds and fog expect temps to not cool a whole lot more from their current state. That means fairly widespread low 70s for much of the area. Previous Discussion... A weak stalled frontal boundary is slowly lifting northward through the area this afternoon as a weak warm front, bringing in warmer and more humid air, as well as kicking off some scattered showers and thunderstorms. These continue to increase in coverage through the late afternoon and into the evening hours. The best coverage looks to be across northern areas and the higher terrain. A second area of showers and storms is likely to develop across southern New Hampshire this afternoon, and is already starting to show up on radar. These gradually drift eastward along the coastline through the evening hours, and into the overnight hours. They may weaken a bit, but increase in coverage through the overnight as forcing improves slightly ahead of a cut off low across the Great Lakes. This keeps the chance of showers ongoing most of the night across Maine, while New Hampshire mostly dries out after the evening activity. A humid night is expected across the area, with low mainly ranging from the mid 60s to the low 70s. Fog along the immediate coastline likely spreads inland through the late evening hours, and lingers through daybreak tomorrow. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/... After a bit of a break during the morning hours, showers and storms increase by late morning across western areas as a cold front approaches from the west. There remains some disagreement amongst the high res guidance as to how expansive the morning convection will be. Should it be less, we likely see better heating through the midday hours, allowing for more instability and a better chance of some stronger storms during the afternoon hours. Scattered storms look likely, but how strong and widespread they become remains a bit uncertain. Either way, more showers and storms move eastward through the afternoon as the front approaches, likely reaching the coastline by the early afternoon hours. It looks like the rain mostly ends by the late afternoon, bringing a drier period for the late afternoon. Conditions remain humid overnight tomorrow night, with patchy fog developing in many spots. Relatively drier air doesn`t begin to arrive until near daybreak on Sunday, and moreso during the day on Sunday. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... ---------------------------------------------------------------- Summary: *Temperatures expected to run above average through early next week. *Pleasant weather likely on Monday, through scattered storms return by Wednesday. ----------------------------------------------------------------- Discussion: A low finally exits the region Sunday morning, bringing generally clearing skies and perhaps a stray thunderstorm over central Maine. High pressure builds just to the southeast over the Atlantic, ushering in hot and moist air through Tuesday. The period of hotter weather concludes by Wednesday, when a low moves across the region, bringing showers and thunderstorms. The end of the week looks generally on the more pleasant side but a stray shower / thunderstorm remains a possibility. Aviation: Generally a quiet period for aviators, but lower flight restrictions are likely with showers and thunderstorms Tuesday night and Wednesday. Some patchy morning fog is also possible in the Midcoast and CT river valley on Monday and Tuesday. The fog could impact sites RKD, LEB, CON, and MHT. Marine: Light southwesterly flow with 3-5 foot seas is expected to start the day on Sunday, with winds and seas gradually decreasing throughout the day as a low exits the region. Quiet seas and light winds are expected through Tuesday morning. Another incoming low will then increase seas and winds during the day Tuesday, with southerly SCA level winds possible by the end of the day and likely continuing through Wednesday night. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... Short Term...Marine fog brings IFR to LIFR to the coastal terminals and AUG this evening, and lingers into at least mid morning tomorrow. Fog is also likely for a brief time across interior terminals later tonight. Fog becomes mainly low stratus along the coast, and lingers most of the day tomorrow, with interior terminals seeing MVFR to VFR conditions return. Showers and storms are likely during the afternoon hours at all terminals. Fog then clears after the rain in the late afternoon, but then valley fog is likely at most terminals tomorrow night. Long Term... Generally a quiet period for aviators, but lower flight restrictions are likely with showers and thunderstorms Tuesday night and Wednesday. Some patchy morning fog is also possible in the Midcoast and CT river valley on Monday and Tuesday. The fog could impact sites RKD, LEB, CON, and MHT. && .MARINE... Short Term...Locally dense fog lingers into tomorrow night. Freshening southwesterly winds ahead of an approaching cold front may bring brief gusts to 25kt tomorrow afternoon and evening. The front slowly clears the waters tomorrow night and on Sunday. Long Term... Light southwesterly flow with 3-5 foot seas is expected to start the day on Sunday, with winds and seas gradually decreasing throughout the day as a low exits the region. Quiet seas and light winds are expected through Tuesday morning. Another incoming low will then increase seas and winds during the day Tuesday, with southerly SCA level winds possible by the end of the day and likely continuing through Wednesday night. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ SYNOPSIS...Palmer NEAR TERM...Clair/Cornwell SHORT TERM...Clair LONG TERM...Palmer AVIATION...Clair/Palmer MARINE...Clair/Palmer