Port Clyde ME to Cape Elizabeth ME Marine Forecast

FORECAST
DISCUSSION

FORECAST FOR ANZ152 CURRENTLY UNAVAILABLE

Area Forecast Discussion National Weather Service Gray ME 645am EDT Thu September 23 2021 Synopsis Warm and humid conditions for early fall continue across the forecast area ahead of a cold front. This front will very slowly cross the region late Friday and Saturday with a period of widespread rainfall likely, along with a few thunderstorms. Improving conditions are expected by the second half of the weekend as drier air arrives from the west. A cold front will then approach the region early next week with another threat for showers. Near Term - Until 6pm This Evening 630AMNo significant updates to the forecast this morning with some small tweaks to the cloud cover. Overall fog development was limited last night compared to the previous mornings. Today will be very similar to yesterday, with the exception of more breaks in the cloud deck, especially along the coastal plain. Current satellite shows the low level stratus deck remains across interior areas in favorable upslope areas, but breaks have formed in the coastal plain. Expect this trend to continue looking at near-term meso-model guidance. Expect a low chance for a passing shower with intermediate periods of clouds as a few showers develop, with the highest likelihood across the foothills and mtns. of NH. Temps will remain above average after a very warm start to the day as low temps remained mostly in the mid-60s. Highs should top out in the mid to upper 70s, with a few locations touching the 80 degree mark. Marine stratus should make another push by this evening as the low level jet begins to increase in strength as the surface cold front approaches from New York. Short Term - 6pm This Evening Through 6pm Friday The cold front begins to approach the area tonight as the closed 500mb low over the Great Lakes begins to move north. This will cause the low level jet to increase with 925mb winds increasing to 35kts. Most models are showing an increased surge of low level moisture as PWAT (Precipitable Water) anomalies begin to increase. This should allow for an increase in stratus formation and possible coastal fog. Mid-level heigheights also begin to lower as the 500mb ridge over the North Atlantic begins to shift further east after midnight. The combination of these two factors should allow for increase in rain shower activity, especially over the Whites. By Friday morning the frontal boundary finally begins to push into the CT River Valley. This boundary will be the focus for moderate rainfall with most areas receiving a 3 to 4 hour window of rainfall. Overall amounts will range from .75" to 1.25" with locally up to 2" across the southeastern slopes of the Whites and Western Maine mtns. Currently the flash flood threat looks low but can't totally be ruled out at this time, especially if the frontal boundary stalls out earlier than the current model consensus. The second weather threat we are watching on Friday is the potential for Severe Weather across mostly NH at this time along the frontal boundary. Storm Prediction Center has the region under a Marginal risk at this time for the potential of gusty winds and a low Tor threat. Overall dynamics look strong with strong shear profiles and favorable hodographs, but how much surface based instability can be mustered on Friday due to sufficient low level cloud cover is the largest deterrent. Most sounding profiles due support some marginal instability with CAPE values in the 400-900 J/KG range across southern NH. Hodograph profiles are classic with a SE veering wind profile and low LCL heights. Will have to watch how this trends over the next 24hrs, but have kept the mention of this threat in the HWO. Long Term - Friday Night Through Wednesday Overview: Upper low will lift thru the Ern Great Lakes to start the weekend...while an upper trough tries to establish itself over the Ern CONUS. Generally unsettled weather and seasonable temps are expected into next week. Impacts: Frontal boundary will stall over or E of the forecast area...allowing moderate to occasionally heavy rain to threaten thru Sat. Forecast Details: Front will continue its slow march across the forecast area Fri night. Upper low lifting into Canada and strong ridging to the E will start to allow the boundary to stall thru the night. The good news is that as the best forcing lifts into Canada the intensity of rainfall should weaken as well. The real question is how much progress does the front make before stalling. The 23.00z GFS is the most progressive...taking the boundary to near New Brunswick before coming to a stop. The 23.00z ECMWF (European Centre for Medium-Range Weather Forecasts) meanwhile keeps the boundary hung up across our forecast area. This is important because there will be a follow up S/WV trough that will support the development of a secondary precipitation shield...one that may entrain moisture from Peter. At this time the ECMWF EPS is fairly aggressive on that scenario affecting at least the Ern half of the forecast...while roughly 50 percent of GEFS members have a second wave of rainfall impacting Wrn ME. As such I have kept likely or higher Probability of Precipitation going thru Sat into Sat night...especially NE of PWM. Once that S/WV trough kicks the front out of the area for good the pattern will be dominated by mean trough.ng. This will keep temps seasonable...with frequent chances for showers in the higher terrain in W/NW flow. Marine Short Term Similar weather pattern over the waters today, with confidence for fog bank development today low, but this should increase later tonight as the surface cold front begins to approach the Gulf of Maine from New York, bringing with it an additional surge of moist low level moisture. The possibility of dense fog, especially for Penobscot Bay area increases on Friday. In addition winds will be on the increase and should begin to flirt with SCA (Small Craft Advisory) conditions by late tonight with SCA (Small Craft Advisory) conditions possible on Friday with 25kt onshore wind gusts and waves building to 5 ft. Long Term Persistent SE flow ahead of approaching cold front will see a few 25 kt wind gusts but seas remaining above 5 ft into Sat. Seas will very slowly diminish thru the day. Areas of dense fog are also possible ahead of the front...as tropical moisture surges Nwd. Generally dry offshore flow will develop for the latter half of the weekend and continues into early next week. NOAA Gray/Portland ME Office - Watches - Warnings - Advisories ME...None. NH...None. Marine None.