Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
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457 FXUS61 KGYX 171036 AFDGYX Area Forecast Discussion National Weather Service Gray ME 636 AM EDT Tue Sep 17 2024 .SYNOPSIS... High pressure will remain entrenched east of the region through midweek before some moisture over the southeastern states builds north increasing the chance for showers south of the mountains Wednesday night and Thursday with cooler temperatures. Canadian high pressure builds in from the north to end the week and through the weekend with seasonable temperatures and dry weather expected. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 635 AM...Valley fog in place again this morning, but should burn off by 12-13Z, maybe a little sooner than previous days given better BL flow. Otherwise should be another warm and mainly sunny day. Previously...590 dam ridge at 500 MB still stretches from roughly the Great Lakes ESE to S of the maritimes, with elongated sfc ridge located beneath. Th ridging slowly breaks down today into Wed, as it bit acted upon by weak waves passing well to our n, and the remnant closed low from the pseudo tropical system now over the Carolinas. After the, what has become, daily morning fog in the valleys, the warm air holds in place today, and with the ridge breaking down will see a bit more of a WSW flow, albeit weak, but should allow the sea breeze to hold off later than on Monday. As such, highs will generally be in the 80-85 range across all but the immediate coast where temps will still get into the mid to upper 70s. Other than some thin and patch cirrus moving through the SW half of the CWA it should be mainly sunny. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... The ridging continues to weaken tonight, as a large mid level col develops between the Great Lakes and the maritimes. So, whatever weak flow there is during the day becomes less tonight. This will allow patchy fog to develop in more areas tonight, and could allow marine lyr to move onshore with fog and low clouds, although likely will be limited to coastal zones. Min temps should be similar to this mornings, generally range from around 50 in the mtns and the colder spots to the mid 50s near the coast and in S NH. There may be more cirrus on Wed, as the ridging breaks sown, but, it should not prevent a mostly sunny day. The lack of flow will prevent much mixing occurring, and max temps will be slightly lower than today, but still should range from the mid 70s near the coast to low 80s elsewhere. && .LONG TERM /THURSDAY THROUGH MONDAY/... BY Wed night, moisture from a low pressure system moving over the Carolinas will lift northward bringing more in the way of clouds and low chances for rain late Wednesday night into Friday. The best chances for rain will be across southern New Hampshire while total precipitation on whole will likely average below normal for the long term period. A cold front moving southwest through Maine will shunt this moisture southward Friday followed by high pressure building in from the north over the weekend. Weak troughing will linger along the East Coast Thursday into Friday, while the majority of model solutions keep any appreciable rainfall south and east of the area. Therefore, the current precipitation deficit for the month of September looks to increase through the end of the week. Highs on Thursday will mainly be in the mid to upper 70s lowering to the low 70s on Friday. A cold front dropping southwest through the area Friday will usher in a cooler and drier air mass over the weekend. High pressure building in behind the front will bring fair weather with highs in the 60s and lows in the 40s over the weekend. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... Short Term...Valley fog at KLEB/KHIE will persist until around 13Z again, with a brief sunrise surprise possible at KCON or KRKD, but otherwise expect VFR into this evening. More terminals will see some fog late tonight, especially along the coast as marine layer moves in. Still, expecting a return to VFR at all terminals during the first half of the morning. Long Term...VFR likely prevails during the day time Wednesday through Saturday. Night time valley fog will bring the potential for IFR/LIFR most nights at KLEB and KHIE. Onshore flow and increasing clouds from a system passing south of New England will also bring the potential for cigs around MVFR thresholds Wednesday night and Thursday night. && .MARINE... Short Term...Winds/seas stay below SCA criteria through Wed night. Long Term...Winds and seas remain below SCA thresholds Wednesday and Thursday. Southerly flow Wednesday shifts NE Thursday as low pressure approaches and stays south of New England. Low pressure passing south of the Gulf of Maine will bring seas building to 5 ft by Friday with continued NE flow with gusts around 20 kts. Seas remain elevated around 5 feet into the weekend with NE winds subsiding from their peak on Friday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...Cempa SHORT TERM...Cempa LONG TERM...Schroeter AVIATION... MARINE...