National Weather Service (2024)

Area Forecast Discussion
Issued by NWS Portland, ME

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-- Discussion containing changed information from previous version are highlighted. --703FXUS61 KGYX 281121 AAAAFDGYXArea Forecast Discussion...UPDATEDNational Weather Service Gray ME721 AM EDT Fri Jun 28 2024.SYNOPSIS...High pressure brings fair weather today into Saturday morning.Low pressure tracking east across Quebec will lift a warm frontinto the area late Saturday bringing rain. A cold front thencross Sunday for continued chances for showers and thunderstormswith locally heavy rainfall. High pressure builds in from thewest Monday bringing mostly dry conditions into the middle ofnext week.&&.NEAR TERM /UNTIL 6 PM THIS EVENING/...630 AM Update...Minor update to T/Tds to align with observedtrends. Otherwise, no changes to the going forecast for today.Previously...High pressure centered over Lake Ontario will slide east acrossNew England providing fair weather today. Northwest winds willbe breezy this morning before relaxing this afternoon as thehigh moves closer to overhead. Highs will range from the upper60s north to the upper 70s across the south.&&.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...High pressure moves into the Gulf of Maine tonight and willgradually move east into the Atlantic during the day Saturday.Return flow around the high and an approaching trough willadvect warmer air and moisture into the region leading toincreasing clouds tonight into Saturday morning. This will leadto lows mainly in the 50s.The approaching trough will lead to low pressure developing overthe Great Lakes Saturday morning with this low tracking ENEacross Quebec into Saturday night. This low will lift warmfront into New England late Saturday with showers breaking outfrom west to east Saturday afternoon. The 00Z model suite is ingood agreement that instability will remain south and west ofthe area through 00Z Sunday limiting the chances for convection.PWATs will be on the rise Saturday afternoon approaching 1.75to 2.25 inches by Saturday evening north to south. These highPWATs combined with building elevated instability will bring thethreat for heavier rainfall Saturday evening into Saturdaynight with more details below in the long term section.&&.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
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7am Friday Update: Overnight trends showing a decreasing heavyrainfall signature for Saturday night...though locally heavyrainfall rates are still likely given ample PWAT values and warmcloud depths...with focus turning more to an increasingconditional threat of severe thunderstorms by Sunday latemorning and afternoon. SPC has added a slight risk to thesoutheastern half of the forecast area with a marginal riskelsewhere. Biggest question mark at this range is timing thecold front...and thus southeastern areas have the greatestpotential for significant destabilization ahead of the arrivingboundary in an area of ample 0-3km and 0-6km shear. Primaryhazard threat looks to be damaging winds with llevel shearorientation favoring bowing line segments where convectiondevelops. Have added mention of this potential to the HazardousWeather Outlook and we will look to refine the details on whereinstability will be sufficient to warrant what could be asignificant severe weather threat.Previous Discussion below...An unsettled weather pattern returns for the weekend. Lowpressure tracking across Quebec will help a warm front and aneventual cold front through the area Saturday night and Sunday.Rain and chances for convection will be in store Saturday nightbefore tapering to showers by daybreak on Sunday. There will beplenty of moisture to work with so locally heavy rainfall ispossible during this period. Attention will be paid to theposition of the frontal boundary and track of the surface low,which could support a swath of heavy rain. WPC has the area in amarginal risk with the window of concern late Saturday nightthrough daybreak Sunday. On Sunday an upper level troughapproaches the area which will help to initiate scatteredshowers and thunderstorms throughout the day. A few showers maylinger into Monday as the upper level trough crosses the areaalthough most of the day should be dry. As the upper leveltrough enters the Gulf of Maine indications are that lowpressure will form. However, models continue to show the area oflow pressure forming east of the area which will keep anyadditional showers offshore and allow high pressure to buildeastward from the Ohio Valley Tuesday and Wednesday bringing dryand seasonable conditions to the area.
-- End Changed Discussion --&&.AVIATION /11Z FRIDAY THROUGH TUESDAY/...Short Term...VFR prevails today with a period of NW windsgusting 15-20 kts from mid morning until early afternoon beforerelaxing later this afternoon. VFR likely prevails tonight intoSaturday morning. Clouds thicken and lower Saturday morning intothe afternoon with -SHRA developing west to east Saturdayafternoon. This will likely introduce periods of MVFR at KHIEand KLEB between 18Z Saturday to 00Z Sunday.Long Term...Numerous showers and thunderstorms with locallyheavy rain Saturday night into Sunday morning will result insub-VFR conditions.&&.MARINE...Short Term...NW winds around 20-25 kts will increase slightlyafter day break continuing marginal SCA conditions. Windssubside later this morning as high pressure moves in with windsand seas staying below SCA thresholds this afternoon intoSaturday morning. Low pressure tracking northwest of New Englandwill bring increasing southerly flow Saturday with winds andseas approaching SCA thresholds Saturday afternoon.Long Term...Small Craft Advisory conditions probable assoutherly flow increases ahead of a cold front Saturday night.Showers and thunderstorms may produce locally gusty winds.Monday...The conditions are anticipated to be below Small CraftAdvisory criteria as winds subside, however some choppy seascould approach 4 ft on the outer waters.&&.GYX WATCHES/WARNINGS/ADVISORIES...ME...None.NH...None.MARINE...Small Craft Advisory until 10 AM EDT this morning for ANZ152>154.&&$$NEAR TERM...SchroeterSHORT TERM...SchroeterLONG TERM...Arnott/Jamison