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fxus61 krnk 190724 

Area forecast discussion
National Weather Service Blacksburg Virginia
324 am EDT Fri Jul 19 2019

high pressure will build across the region through the weekend
resulting in a 3 day heat wave that will feature temperatures
about 10 degrees above normal. A cold front should cross the
area Monday bringing cooler and less humid weather by the middle
of next week.


Near term /through tonight/...
as of 250 am EDT Friday...

Quiet weather this morning will turn to hot weather today, as 8h
temps rise to 21 to 24c. There are no changes planned to the current
heat advisory, but thinking a westerly downslope component to the
low/mid level winds may drop dewpoints a couple degrees this
afternoon east of the mountains. Still will keep the advisory,
despite possibly not getting to 105 degrees for the heat indices for
2 consecutive hours. This heat has been advertised for the past
week, so should not come as a surprise.

As far as thunderstorm chances, there may be just enough weakness
in the upper ridge to allow for a few storms over the mountains
today, but coverage will be less than Thursday. Have cut pops back
to 20-30 at best.

Should see plenty of sunshine today, with highs in the mid 80s to
near 90 in them mountains, to 90s east, ranging from the lower 90s
in the NC foothills to upper 90s east of Lynchburg and Danville.
Heat indices will peak out around 105 degrees from Lynchburg to
Danville east, just over 100 across the Virginia foothills and Roanoke
valley, and mid 90s across portions of the New River valley and
Alleghany lower elevations such as Covington. To escape the heat you
will nee to head to Mt Rogers or Beech Mountain. Despite the
heat, none of our climate sites are expected to get close to
record highs today.

Showers/storms are going to fade in the evening. Skies will be
mainly clear. Some models are showing potential for an isolated
storm overnight with a vort lobe moving across the central
Appalachians, so could see something across the WV mountains toward
the mountain Empire late tonight.

No change in the forecast with lows in the upper 60s to lower 70s
mountains, to mid 70s east.

Forecast confidence is high for this cycle.


Short term /Saturday through Sunday night/...
as of 320 am EDT Friday...

Posted an excessive heat watch for Buckingham, Appomattox,
Charlotte and Halifax counties Saturday into Sunday.
This will likely be the warmest stretch of weather for our forecast
area so far this Summer. The heat and humidity will contribute to an
extended stretch of elevated heat indices. With 850 mb temperatures
commonly into the low to mid 20s celsius, this will lead to daytime
ambient high temperatures into the mid/upper 80s to the mid/upper
90s this weekend. Increasing cloud cover on Sunday may help knock
ambient high temperatures down a couple degrees compared to
Saturday. Little relief is expected at night, with lows in the upper
60s to the mid to upper 70s Saturday nights, and lows in the mid-
upper 60s to low-mid 70s Sunday night.

For headlines, excessive heat criteria for our forecast area
involves maximum heat indices of 110f or greater with intervening
lows of 77 or greater. The forecast brings Buckingham County
southward to Halifax County to levels close to that criteria, while
falling short elsewhere. Will Post addition heat advisories for this
period once we enter the shorter range. Each afternoon, there should
be some mixing that in the afternoon helps locally reduce dewpoints
as temperatures rise that could affect (e.G. Reduce) heat index
values. Will continue to message the heat in the severe weather potential statement.

Under the large subtropical ridge, convective chances through the
period are generally on the smaller side into Sunday. If any storms
were to develop, these would tend to be confined to the terrain.
Into Sunday, the subtropical heat ridge fractures, leaving US in a
weakness in the ridge. This should Foster generally greater cloud
cover and greater thunderstorm coverage. Possible that one or two
may become strong and produce gusty winds and brief heavy rainfall,
but it remains low-predictability which area(s) may see this threat
relative to others.

Take extra precautions...if you work or spend time outside. When
possible...reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when possible
and drink plenty of water.


Long term /Monday through Thursday/...
as of 115 PM EDT Thursday...

On Monday, we expect to see a full transition from the hot upper
ridge that has been over the region, to one of a longer wave trough
positioned over the East Coast through at least mid-week. At The
Heart of this transition will be a strong cold front which is
expected to cross the region on Monday. Showers and storms are
forecast to be in progress by the mid to late morning across western
sections of the area with all areas of the forecast area having
greater than a 50 percent chance of showers and storms during the
afternoon. Temperatures on Monday will be notably cooler as compared
to the several days before thanks to the passage of the cold front,
abundant cloud cover, and precipitation across the area. Highs will
range from the upper 70s to around 80 across the mountains with mid
80s to near 90 across the Piedmont.

As we progress into mid-week, the upper trough builds even more
across the east with surface high pressure building into the mid-
Atlantic. Precipitation chances will linger Monday night into
Tuesday across mainly eastern and southern sections of the region,
nearest the cold front which is expected to stall near the NC/SC
border. The general trend across the entire area will be for drier
and cooler weather. By Wednesday temperatures are expected to
average around five degrees below normal for this time of year.


Aviation /08z Friday through Tuesday/...
as of 118 am EDT Friday...

Expect a period of MVFR at lyh/Dan this morning with IFR or
lower at blf/lwb and bcb with mainly fog and/or low cigs.

Friday should generally bring VFR conditions to the forecast
area once the morning fog/low clouds burn off. A broken layer of
cumulus will scatter out by late morning.

Isolated to scattered thunderstorms will be possible across
mainly the southwest and far west part of the cwa, which at this
point should not impact any of the taf sites.

Forecast confidence is high, except medium on how low
clouds/vsbys drop at times this morning in the west.

Extended aviation discussion...

For late Friday night into Saturday, high pressure will
strengthen overhead, with subsidence curtailing, but not
completely eliminating, the potential for diurnally driven
showers and storms Saturday afternoon. However coverage looks
even less than Friday with any storms likely confined to the
higher peaks along the Blue Ridge at this point. Otherwise, VFR
outside of some late night fog in the mountain valleys, with
potential to restrict visibility for a few hours prior to
daybreak at terminals such as klwb and kbcb.

A bit better coverage of showers/storms is expected late Sunday
and Monday, associated with the approach and passage of a cold
front. The front will also bring a wind shift later Monday. This
front may slow down enough to keep storm chances east of a roa-
tnb line Tuesday.


Rnk watches/warnings/advisories...
Virginia...heat advisory from noon today to 8 PM EDT this evening for
Excessive heat watch from Saturday afternoon through Sunday
evening for vaz046-047-058-059.
NC...heat advisory from noon today to 8 PM EDT this evening for



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