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Thunderstorms with lightning (very, very frightening!)
North Bay, now.
Link to tweet
And, from (sorry for format)
https://www.wrh.noaa.gov/total_forecast/getprod.php?afos=afdmtr&wfo=mtr&version=0&print=yes&new=1&font=120
DISCUSSION...as of 3:30 AM PDT Sunday...Extremely busy night at
the office between extreme heat and a red flag warning for
thunderstorm risk, but the main focus has been a powerful, fast
moving severe thunderstorm that developed off the Central Coast
late last evening and has been producing frequent lightning and
erratic gusty outflow winds of 45 to 60 mph (update peak gusts 60-
75mph since the AFD was written). Due to the very frequent
lightning, expect wildfire starts to start where lightning occurs,
especially given the particularly dry vegetation and hot and dry air
mass near the surface below the elevated moisture aloft.
Latest WRF/NAM output show a much more aggressive push of MUCAPE
(a measure of potential energy at a specific level in the
atmosphere), PWATs (total moisture available in the atmosphere),
and modified total totals >34 across the region through Sunday and
into early Monday. Thunderstorms will develop primarily in the
core of a pair of elevated moisture surges rotating into the
region around the oppressive high pressure driving the excessive
heatwave and a 578dm 500mb trough centered just off the NW
California coast. This trough will further enhance elevated
convection as it transitions into the area of best upper level
dynamics on the eastern flank of the trough, which is what we have
seen occurring over the last day, and particularly tonight. Expect
new thunderstorms to rapidly enhance as they moved into this
preferred region throughout the next 24-36 hours. Due to these
conditions, the Red Flag Warning for dry thunderstorms has been
extended until Monday morning.
In addition, the excessive heat warning remains in effect through
at least Wednesday. Today`s forecast high temperatures were
increased on the overnight shift as previous days have
outperformed even the hottest model data and it is expected that
both day and night time temperatures will run warmer than
modeled, even after bias corrections. In addition, the heat
advisories for the nearshore zones will not longer just be issued
through the day but also through the night as overnight lows
struggle to drop below 70 degrees even at the coast. Without
significant overnight cooling, the days will start warmer and stay
hotter midday even longer through the day, both of which will add
to accumulating heat stress across the major urban areas. Many
have asked if these thunderstorms will mean it will be much cooler
today, and the answer unfortunately is no. This is because the
hottest, driest air is hovering just above the surface and up a
few hundred to thousand feet. Meanwhile, these thunderstorms are
sitting at about 10000 feet or higher, much too high for the
moisture to make any significant difference for us at the ground.
The increased albedo from these clouds in place will bring some
very minor cooling related to additional insolation heating from
the sun, however, the main reason we are so hot is because of the
hot dry air near the surface, not so much the insolation from the
sun.
the office between extreme heat and a red flag warning for
thunderstorm risk, but the main focus has been a powerful, fast
moving severe thunderstorm that developed off the Central Coast
late last evening and has been producing frequent lightning and
erratic gusty outflow winds of 45 to 60 mph (update peak gusts 60-
75mph since the AFD was written). Due to the very frequent
lightning, expect wildfire starts to start where lightning occurs,
especially given the particularly dry vegetation and hot and dry air
mass near the surface below the elevated moisture aloft.
Latest WRF/NAM output show a much more aggressive push of MUCAPE
(a measure of potential energy at a specific level in the
atmosphere), PWATs (total moisture available in the atmosphere),
and modified total totals >34 across the region through Sunday and
into early Monday. Thunderstorms will develop primarily in the
core of a pair of elevated moisture surges rotating into the
region around the oppressive high pressure driving the excessive
heatwave and a 578dm 500mb trough centered just off the NW
California coast. This trough will further enhance elevated
convection as it transitions into the area of best upper level
dynamics on the eastern flank of the trough, which is what we have
seen occurring over the last day, and particularly tonight. Expect
new thunderstorms to rapidly enhance as they moved into this
preferred region throughout the next 24-36 hours. Due to these
conditions, the Red Flag Warning for dry thunderstorms has been
extended until Monday morning.
In addition, the excessive heat warning remains in effect through
at least Wednesday. Today`s forecast high temperatures were
increased on the overnight shift as previous days have
outperformed even the hottest model data and it is expected that
both day and night time temperatures will run warmer than
modeled, even after bias corrections. In addition, the heat
advisories for the nearshore zones will not longer just be issued
through the day but also through the night as overnight lows
struggle to drop below 70 degrees even at the coast. Without
significant overnight cooling, the days will start warmer and stay
hotter midday even longer through the day, both of which will add
to accumulating heat stress across the major urban areas. Many
have asked if these thunderstorms will mean it will be much cooler
today, and the answer unfortunately is no. This is because the
hottest, driest air is hovering just above the surface and up a
few hundred to thousand feet. Meanwhile, these thunderstorms are
sitting at about 10000 feet or higher, much too high for the
moisture to make any significant difference for us at the ground.
The increased albedo from these clouds in place will bring some
very minor cooling related to additional insolation heating from
the sun, however, the main reason we are so hot is because of the
hot dry air near the surface, not so much the insolation from the
sun.
8 replies
= new reply since forum marked as read
= new reply since forum marked as read
High humidity
High temps (which remain even early in the morning)
Loud thunderstorms (& lots of lightning)
