Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 251044 AFDGYX Area Forecast Discussion National Weather Service Gray ME 644 AM EDT THU AUG 25 2016 .SYNOPSIS... High pressure will remain anchored well to our south today allowing for warm southwesterly flow to continue. A few thunderstorms may move into New Hampshire late this afternoon but most of the region will remain dry. A cold front will approach late tonight and Friday with more chances for showers and thunderstorms during this time. High pressure will return for Friday night and Saturday with a drier air mass. Showers and thunderstorms may return early next week as another frontal system approaches. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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640 AM Update...Little change to the going forecast. Just a few minor adjustments to sky cover and temperatures based on latest trends in observational data. Forecast remains on track. Previously... Cirrus associated with a weak short wave trough and some higher- level warm air advection will allow for mostly cloudy skies for a portion of the region early this morning. However, this should move out early and allow for a good amount of sun for the balance of the morning. Another impulse will then approach from the west allowing for a return to a fair amount of clouds this afternoon. Forcing for ascent will be pretty weak this afternoon so most of the region is expected to be dry. However, a couple of showers or thunderstorms may move into western zones late in the day. Lapse rates will be weak as well as the deep layer shear so we are not expecting severe weather. However, any storms that do move in late would likely have torrential downpours as precipitable water values rise to around 1.75 inches and warm cloud depths deepen. Again, most of the region will likely remain dry however.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... Fairly low confidence exists in the PoP/Wx forecast for late tonight and Friday morning as models differ on strength of forcing and resulting potential convection. A few of our mesoscale models as well as global models (ECMWF most robust) indicate that convection will develop across Upstate NY overnight as a weak short wave trough provides modest forcing for ascent in an area of positive theta-e advection. The resultant cluster of showers and possibly thunderstorms then moves into western NH late tonight or early Friday morning, then dies out as it tries to push into Maine. Not completely sold on this as some convective feedback may be at play there, but can`t completely rule out the scenario put forth by the 00z ECMWF, RGEM, and to some extent the ARW and NMM. Have therefore gone with chance PoPs for much of NH late tonight into early Friday morning to allow for the possibility of showers and thunderstorms. We wouldn/t expect severe weather with this at this point, but a frequent lightning and very heavy downpours would be on the table. Again, this is conditional upon development in the first place. PoPs for the remainder on Friday are a little tricky as the aforementioned short wave trough moves through fairly early and deep layer westerly flow dries things out. This may leave much of the region high and dry and quite hot for much of Friday. However, if the SFC front hangs back long enough, another round of showers and thunderstorms will be possible on the coastal plain swwd to southern NH. Another possible scenario is if convection does indeed develop to our west late tonight and arrives later than expected, it could potentially continue eastward into Maine during the morning and early afternoon hours as the atmosphere destabilizes as heating takes place. Again, confidence is not high in any one of these scenarios at this time. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Expect a drying northwest flow Friday night as high pressure builds in from Ontario and Quebec. High pressure then crosses into northern New England on Saturday with cooler temperatures, but still above normal for late August. The high moves east on Sunday with a south to southeasterly flow developing. This will keep temperatures a little bit cooler especially toward the coast. Meanwhile, a shortwave trough moving through Quebec and toward northern Maine will set up another frontal passage Sunday night with showers possible with the front. Models seem to be in a little better agreement on the timing of this, with the shower chances ending by Monday morning. High pressure building in from the west next week will keep conditions dry with temperatures a few degrees above normal. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... Short Term...VFR conditions are expected today outside of widely sct showers and thunderstorms in western NH late this afternoon. Some stratus and fog may affect the coastal plain late tonight and early Friday morning as the low levels moisten up. In addition, there is a low probability of showers and thunderstorms late tonight and early Friday morning, particularly across NH. Long Term...Generally expect VFR conditions across the area through the weekend, though some showers are possible as a cold front arrives Sunday night which could bring MVFR conditions especially in northern areas. && .MARINE... Short Term...A small craft advisory has been issued for later this afternoon and tonight for the ocean waters as winds increase and seas build. Infrequent marginal SCA conditions may occur in the bays as well, but lower confidence there. Winds and seas gradually subside Friday. Long Term...High pressure crosses the Gulf of Maine this weekend with light winds expected. A cold front will arrive from the northwest Monday morning, though winds with the front should remain below advisory levels. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory from 5 PM this afternoon to 8 AM EDT Friday for ANZ150-152-154. && $$ NEAR TERM...Ekster SHORT TERM...Ekster LONG TERM...Kimble

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