Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
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440 FXUS61 KGYX 111506 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1106 AM EDT Thu Jul 11 2024 .SYNOPSIS... Hot and humid conditions linger today as a slow moving cold front stalls near the coastline by tonight. Scattered showers and a few thunderstorms are possible again Friday as the front lingers over the region. A few more scattered showers and storms are expected over the weekend with continued hazy, very warm and humid conditions. Slightly cooler conditions can be expected right along the shoreline with periods of maritime fog. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1105 AM Update... Quick update to send products removing the Flood Watches for the region. Some rivers remain high, but will likely hold below flood stage. This is dependent upon convection this afternoon which could hamper the receeding of water in some areas. Remaining very hot today in southern NH and southwest ME. 930 AM Update... Latest radar imagery shows the main batch of showers now exiting the Mid-Coast region of ME with just a few light showers trailing behind it across coastal southwestern ME. Went ahead and tightened up PoPs to account for these latest trends. Latest mesoscale guidance continues to indicate the potential for additional showers and storms to develop this afternoon, mainly over interior western ME. Any storm will be capable of producing locally strong winds and heavy rainfall. Lastly, expanded the heat advisory to include interior York County as heat indices should approach 95 degrees this afternoon. Previously... 6:45am Update... Refreshed POPs, temps, and dew points for today based on the latest trends. One last heavy batch of showers and storms are currently moving through the foothills into central Maine. Temps are starting off very warm across southern areas this morning, so don`t see them having any trouble getting into the 90s this afternoon. Previous... One last batch of lighter showers and storms moves through during the morning hours today, reaching farther south than the overnight activity did. Hot and humid conditions linger today as a slow moving cold front stalls near the coastline through tonight. With these conditions, a few more showers and thunderstorms are possible again this afternoon, with gusty winds possible in any stronger storms. These look to remain isolated to scattered, with the best chance across northern areas. Farther south, heat indices reach 95 degrees again today as little relief is brought from the rain. It looks to be borderline heat advisory conditions for interior southern Maine today, but with the morning leftover convection moving through the thinking is that these areas fall just short. Should either the temps or dew points end up a degree warmer than the current forecast, than these may need to be expanded. Onshore flow keeps the coastline cooler again today. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... Another warm and humid night is expected tonight as the front stalls near the coastline. This leads to patchy fog developing again tonight, especially through the valleys. Any leftover showers dissipate by late in the evening, making for a mostly quiet overnight. Friday looks quite similar to today, but just a bit less humid as the stalled front inches slightly farther offshore. This allows for better mixing of dry air during the afternoon, and also allows the warmer temps to reach the southern coastline on southwesterly flow, with temps warming to near 90 degrees. Some isolated showers and thunderstorms are possible again during the afternoon hours as a weak trough swings through New England. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... An anamolous and large upper level ridge centered well out into the Atlantic continues to be one of the primary drivers in our weather conditions for much of extended portion of the forecast. A deep moisture supply with high PWATs as well as high surface dew points will dominate much of the region into next week. At the same time, disturbances, albeit weak, will be moving through this charged atmosphere leading to periods of scattered showers and thunderstorms, primarily during the afternoon and away from the shoreline where seabreezes will be common. We begin the long range on Friday with temperatures well into the 80s to around 90 degrees. 12Z guidance suggests that the flow may be sufficiently enough from the southwest to allow the Seacoast of Maine and southwest coast of Maine to encroach on 90 degrees as well. Temperatures will be cooler along the Midcoast region near the shoreline due to an onshore component to the winds. Surface dew points will be on the high side but not extreme with readings in the upper 60s to lower 70s. The combined temperatures and dew points will allow apparent temperatures to reach the lower to mid 90s in some areas. This will be very close to more areas reaching Heat Advisory Criteria. Along with the heat and humidity, a stalled out frontal boundary and approaching upper level trough will allow for the initiation of scattered showers and possibly a thunderstorm, mainly during the afternoon and early evening hours. Model ensembles suggest Saturday will be a couple degrees cooler as the stationary front begins to move to our east and offshore. Dew points will drop a couple degrees. However, it will still be very warm, especially away from the shore. The chance for any showers and thunderstorms will be relatively low during this period. The end of the weekend on Sunday will feature more sunshine and slightly less humidity. Nevertheless, this sunshine will allow temperatures to reach the upper 80s to mid 90s in southern and central areas outside the mountains. Similar conditions will continue through early next week with surface temperatures in the upper 80s to mid 90s and dew points in the 65 to 70 degree range. In essence, it will continue to remain very warm to hot and continued muggy with primarily scattered afternoon showers and thunderstorms mainly away from the immediate shoreline. There will be the potential for a slight reduction in the heat and humidity as we head into the midweek period next week. An upper level trough and cold front from Canada may take aim at New England. However, at this range out in time, there is much uncertainty in this. With the heat and humidity over the cooler Gulf of Maine waters, patchy fog can be expected along and near the coastline and mainly at night and during the morning hours. Interior valley fog can be expected as well through much of the extended forecast. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... Short Term...A brief period of IFR conditions remains possible this morning following a batch of showers, then mainly VFR return today, except at RKD where marine fog keeps LIFR to IFR mostly ongoing through tonight. Valley fog likely returns for a period at most terminals tonight, then VFR conditions return tomorrow for all terminals. Long Term...There will be scattered showers and thunderstorms throughout the extended forecast with the exception of Sunday. This will lead to brief periods of LIFR conditions in locally heavy rainfall. Nighttime patchy fog will lead to some locations having low visibilities and ceilings especially along and near the coastline most nights and early morning periods. && .MARINE... Short Term...A SCA remains in effect into this evening as southerly flow continues ahead of a slow moving cold front. The front stalls near the coastline tonight, with winds gradually easing, and seas taking a bit longer to settle below 5ft. The front lingers across the waters through tomorrow night. Long Term...A southerly flow will dominate the coastal waters through the long range portion of the forecast. Winds and seas will remain below SCA thresholds. Winds may increase during the late morning and afternoon periods along and near the coastline due to the added component of the seabreeze circulation. Patchy fog will allow for low visibilities at times over the waters especially during the nighttime and morning periods. && .HYDROLOGY... Overnight flash flooding across parts of northern New Hampshire and northwestern Maine transitions to a more areal flood threat as water continues to drain into the small and medium sized river and stream basins. Scattered thunderstorms this afternoon could bring localized flooding threats should they hit areas affected last night, but otherwise the threat for new flooding has mostly passed at this time. Rivers and streams across these northern areas will remain fast flowing and dangerous to swimmers and recreation through today as flow rates remains high. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Heat Advisory until 8 PM EDT this evening for MEZ018. NH...Heat Advisory until 8 PM EDT this evening for NHZ010-012>014. MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ150- 152-154. && $$ Cannon