Scientific Forecaster Discussion
fxus61 kbtv 291118
Area forecast discussion
National Weather Service Burlington Vermont
718 am EDT Sat Apr 29 2017
above normal temperatures expected today before a cold front
brings a few isolated to scattered rain showers to the north
country today, followed by noticeably cooler temperatures
Sunday. A large strengthening low pressure system with a warm
front extending eastward into the northeast will bring another
chance for rain starting later on Sunday. This system will
continue unsettled weather over the north country for the first
half of the work week.
Near term /through Sunday/...
as of 718 am EDT Saturday...mostly cloudy to overcast skies
this morning with increasing winds and a slight to low chance of
scattered showers as a mid-level shortwave moves across the
region through midday. Southerly winds will shift out of the
west to northwest behind the shortwave with a brief period of
ridging this evening through Sunday morning.
Temperatures remain mild today as the day starts off in the 50s
to low 60s. Expect afternoon Max temperatures to reach the 60s
to low 70s before winds shift out of the north to northwest and
cooler air begins to filter in. Overnight lows Saturday night
generally in the 30s with clearing skies for the first half of
the night under the aforementioned ridging.
Sunday clouds increase early as the ridge axis at the surface
weakens and shifts east. Warm front associated with large
strengthening closed low in the central USA will influence the
north country. Models continue to differ on placement of the
front and associated precipitation. Have leaned towards cooler
solution of NAM and European model (ecmwf) with clouds spreading across the north
country earlier and cooler temperatures over the area as the
warm front is draped across the region. Noticeably cooler Max
temperatures expected to be in the 40s for northern half of the
area and mid 50s to around 60 for southern portions.
Short term /Sunday night through Monday night/...
as of 321 am EDT Saturday...still plenty of uncertainty on
position of surface boundary and associated impacts on weather
and temps across our cwa. Latest trends have been to lift this
boundary north of our cwa on Monday...placing US in the warm
section...except southeast flow around anticyclone over northern
Maine...may keep eastern/central VT cooler. Have utilized a
blend of high res data for grids to show sharp gradient in
thermal fields from highs in the mid 50s to lower 60s
eastern/central Vermont to near 80f western dacks from Edwards to
Malone. Have noted low level northeast winds at mss on
Monday...which may keep the slv locked in cooler maritime
airmass with highs only in the 60s. As warm front lifts from
south to north across our cwa on Sunday night...expect some
scattered showers...have placed likely pops along the
international border...where best lift/moisture is located.
Developing mid/upper level ridge and associated mid level dry
air should keep most of Monday dry...before sharp front arrives
on Monday night. Developing southerly winds will help advect
deeper moisture with pws >1.0 and weak instability. Have mention
schc for thunder on Monday night with likely to Cat pops.
Highest pops/qpf will be western section...with boundary
weakening as it shifts eastward overnight. Overnight lows remain
above normal with values mainly 40s to lower 50s.
Long term /Tuesday through Friday/...
as of 321 am EDT Saturday...mid/upper level trof continues to
develop across the eastern Great Lakes/NE conus on Tuesday into
weds...with cooler temps and unsettled weather. The combination
of short wave energy aloft in the stream winds and weak
secondary cold front will produce more terrain focused precip on
Tuesday. Have mention likely pops in the mountains and chc in
valleys with qpf values between 1 and 3 tenths of an inch.
Progged 850mb temps start between 4-6c...but cool to 0c by 00z
weds...supporting highs with a well mixed boundary layer in the
mid/upper 40s mountains to l/M 60s warmer valleys. Low level
cold air advection conts into weds with progged 925mb temps
approaching 0c by 12z weds with breezy northwest winds. Moisture
in the west to northwest flow aloft slowly dissipates...along
with the chances for precip. Expect some lingering
upslope/terrain driven rain/snow showers on weds morning...with
any qpf very light. After a brief period of dry weather weds
afternoon into Thursday...next large scale system will impact
our region late Thursday into the weekend. This looks to produce
a prolonged period of wet weather with cool temperatures.
Latest ensemble data and 00z ECMWF supports a mid/upper level
low becoming closed off across the eastern conus with deep
southerly flow advecting a plume of rich moisture into our cwa.
Have increased pops to likely for Friday...with temps near
normal for highs and above normal due to clouds/precip for
overnight lows. Current trends would suggest the unsettled
weather continues into next weekend...with highs mainly in the
mid 40s to mid 50s and lows mainly in the 40s.
Aviation /11z Saturday through Wednesday/...
through 12z Sunday...VFR conditions are expected to persist
through the period with increasing mid/high clouds lowering to
6-10kft. Isolated showers possible as a weak upper disturbance
traverses across the north country today. Brief ridging this
afternoon and most of tonight will result in dry conditions
through 12z Sunday. Clouds increase towards sunrise Sunday,
ahead of approaching warm front.
Winds out of the south to southwest less than 10kts this
morning will shift west to northwest behind the upper
disturbance during the mid-day. Wind speeds will quickly
increase with gusts 15-25kts developing during the late morning
through the afternoon hours. Winds will subside after sunset at
10kts or less.
Sunday: VFR. Chance rain showers.
Sunday night: VFR. Chance rain showers.
Monday: VFR/MVFR. Windy with gusts to 35 kts. Chance rain showers.
Monday night: MVFR. Likely rain showers...tsra.
Tuesday: VFR. Breezy. Likely rain showers.
Tuesday night: VFR. Chance rain showers.
Wednesday: VFR. Chance rain showers.