Scientific Forecaster Discussion
fxus61 kakq 190227
Area forecast discussion
National Weather Service Wakefield Virginia
1027 PM EDT Thu Jul 18 2019
high pressure remains off the southeast coast through the weekend.
A trough of low pressure lingers across the area tonight, then
pushes south into the Carolinas Friday. A cold front approaches from
the west Monday, ending the current heat wave.
Near term /until 8 am Friday morning/...
as of 1000 PM EDT Thursday...
Latest analysis indicates a sfc trough across the region that
has aided in sustaining tstms through the County Warning Area this evening.
Finally seeing the coverage and intensity weakening now over he
past hr and should see these trends continue through 06z. Some
locally heavy rain/minor flooding and even isolated strong to
severe wind has been observed earlier this evening with the
storms. Will linger 20-30% pops along the coast through 06-09z,
with generally diminishing cloud cover. Warm and muggy
overnight with lows in the lower- mid 70s west of I-95 and mainly
in the mid to upper 70s to the east.
Short term /8 am Friday morning through Sunday/...
as of 345 PM EDT Thursday...
Old fashion heat wave setting up this weekend with the highest heat
index values around these parts since July 2012. It starts Fri but
lingering trof/boundary may spark off some late day storms across
sern Virginia/NE NC. Will carry low chc pops across the se, otw mstly
sunny/hot. Highs 95-100 combined with dew points in the mid-up 70s
results in heat index values 105-110 over most of the fa except arnd
110 (excessive heat warning criteria) across portions of the east
and se. Warm and muggy Fri night. Lows 75-80.
The heat peaks Sat as the airmass stays capped. Mstly sunny/hot and
humid with highs upr 90s-lwr 100s except mid 90s along the coast.
Widespread heat index values btwn 110-115 will likely lead to an
excessive heat warning across most of the fa. Warm and Sat night.
Lows mid 70s-lwr 80s.
Continued mstly sunny/hot and humid sun. The cap breaks down a bit
late in the day allowing for sct convection to drift east off the
Blue Ridge and into the Piedmont. Highs 95-100 with heat index
Heat related headlines include a heat advsry (105-110) Fri for all
zones except sern VA/NE NC where an excessive heat warning (around
110) will be issue from Fri thru late Sat given the high confidence
in the Sat forecast and little if any cooling at Fri night. Sunday
is still a bit in question at this point so plan on holding off on
any headlines for now. Plenty of time to extend them as needed.
Long term /Sunday night through Thursday/...
as of 415 PM EDT Thursday...
Guidance continues to suggest a fairly abrupt cool down by
Tuesday as a long wave trough sets up across the eastern half of
the country. The associated cold front will approach the area
Monday and then slowly move across the region Monday afternoon
into Monday night. This will lead to another hot day on Monday,
although likely not as hot as Saturday and Sunday, especially
due the clouds and numerous showers/storms in the afternoon in
advance of the front. Still, expect highs well into the lower-
mid 90s with dew points in the middle 70s, so especially the
eastern half of the forecast area may need another heat related
headline. In addition, with the frontal passage, there is
certainly a risk for severe weather with stronger wind fields
aloft due to the lowering heights.
The front takes some time to pass south of the area with it
really not passing south of the area until Tuesday morning per
the GFS. The front then stalls south just south of the area
until it finally pushes further south on Thursday. As such,
there should be plenty of clouds and some showers especially
south on Tuesday. Will continue with chance pops across the
area, with likely pops far south Tue afternoon. Perhaps less
showers and clouds on Wednesday, but with the front nearby will
need to maintain chance pops across the south. Much of the area
dry Thursday, although small chance pops south. Highs generally
dropping back to the low-mid 80s for Tue and Wed, then mid-upper
80s Thursday with more sunshine.
Aviation /02z Friday through Tuesday/...
as of 735 PM EDT Thursday...
Prevailing VFR conditions are expected at the terminals through the
00z taf period. Tstms have developed and are ongoing across
central/south-central Virginia...with additional tstms across the Virginia
Northern Neck. Expect these tstms to continue to move eastward
during the next few hours before slowly weakening after 02-03z. Ric
will be impacted by 00z, while tstms are possible at orf/phf by
~02z. Included a tempo group for thunderstorms and rain at ric, while only mentioning
vcsh at orf/phf. The chc of tstms is lower at sby/ecg, but will
continue to amend the tafs if needed. Once again, MVFR cigs, gusty
winds, and IFR visibilities are likely in any tstm. Showers (and even a few
tstms) may linger invof southeast Virginia through 04-06z before completely
dissipating. SW winds will remain aob 12 kt through the taf period.
Outlook... Bermuda high pressure dominates over the weekend capping
any convection from developing Fri/Sat (w/ the exception of a chc of
aftn tstms across NE nc). The High Breaks down a bit sun allowing
for some late day convection over the Piedmont. A better and more
widespread chc for convection comes later Mon as a cold front
approaches the area.&&
as of 400 PM EDT Thursday...
Generally quiet marine conditions through the weekend with the
Bermuda high remaining parked southeast of the area through the
weekend. Still seeing south- southwest wind at 10-15kt this
afternoon. However, these southerly winds should relax to 5-10kt
tonight and remain at 5-10 Friday into Fri evening. Will
increase winds to south- southwest 10-15 kt Saturday into
Monday. A cold front will pass across the waters Monday night
into Tue morning leading to winds shifting to the north to NE for
Tue into Wed. Southeast swell of 3-4 ft will continue over the open
waters with waves 1-2 ft in the Bay.
* due to unrepresentative temperatures at the Norfolk Intl
Airport today (the ASOS reported a daily Max of 97f), the high
temperature from the co- op station was used for today with a
high of 94f. This matches close to surrounding sites (ngu was
93f and the VA tech installed mesonet station close to orf was
Upcoming heatwave may challenge or break record highs and/or
record high lows (esp from Fri through sun).
Richmond record high record high low
Fri (7/19) 101/194277/2013
Mon (7/22) 103/195279/2011
Norfolkrecord highrecord high low
Fri (7/19) 101/194284/1942
Mon (7/22) 102/201182/2011
Salisburyrecord highrecord high low
Fri (7/19) 99/197778/2013
Mon (7/22) 104/193080/2011
Elizabeth cityrecord highrecord high low
Fri (7/19) 105/194280/2012
Mon (7/22) 104/195279/2011
as of 130 PM EDT Thursday...
Kakq radar is back to normal operation.
Maryland...heat advisory from 11 am to 8 PM EDT Friday for mdz021>025.
NC...excessive heat warning from 11 am Friday to 8 PM EDT Saturday
Virginia...heat advisory from 11 am to 8 PM EDT Friday for vaz048-060>062-
Excessive heat warning from 11 am Friday to 8 PM EDT Saturday