Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/13/20
Area Forecast Discussion
National Weather Service Lincoln IL
806 PM CST Thu Nov 12 2020
.SYNOPSIS...
Issued at 301 PM CST Thu Nov 12 2020
A few showers will impact north-central Illinois this
evening...mainly north of the I-72 corridor. After that, chilly
and dry weather is anticipated for Friday with high temperatures
only in the 40s.
&&
.UPDATE...
Issued at 806 PM CST Thu Nov 12 2020
The cold front is about to enter our NW counties on its way across
the remainder of Illinois tonight. Radar returns are deceiving
this evening as the 00z KILX sounding verifies a deep dry layer
below 700 mb. Galesburg did report a brief period of light rain,
but just trace amounts are most likely going to be the rule the
rest of this evening. Therefore, we lowered the PoPs across our
northern counties and removed any mention of precip generally
south of Canton to Danville. Mainly 20-30 pct chance PoPs were
left across the north, but confidence in even that verifying is
low.
The bigger story will be the gusty NW winds that develop behind
the cold front, where 25-30 mph winds are being reported upstream
in Iowa. Efficient momentum transfer behind the front could even
support a few gusts near 35 mph. The corridor of stronger winds
will generally last about 2 hours before wind speeds diminish. A
high pressure center pushing into Illinois on Friday will produce
a greatly reduced pressure gradient and much lighter winds by
Friday afternoon.
Low temps tonight will vary greatly from NW to SE across our CWA.
Temps are expected to drop into the mid 20s by sunrise on Friday,
while areas south of I-70 will be able to remain above freezing
in the mid to upper 30s.
A chilly day is on tap for Friday, under clear or clearing skies.
Highs will struggle to climb through the 40s.
&&
.SHORT TERM...(This evening through Friday)
ISSUED AT 301 PM CST Thu Nov 12 2020
A cold front currently analyzed from Lake Superior southwestward
to near Kansas City will swing through central Illinois tonight.
Regional radar mosaic indicates a band of light snow behind the
front across southern Minnesota into northern Iowa: however, this
band will shift into Wisconsin and will remain well north of the
KILX CWA. Of more importance are radar echoes developing ahead of
the boundary across northeast Missouri into southeast Iowa. CAMs
are all in agreement that showers will develop across this area,
then shift eastward across the northern half of the CWA this
evening. Given the initially dry boundary layer characterized by
dewpoints in the 30s, think it will take awhile for any precip to
reach the ground. Once the atmospheric profile moistens
sufficiently, sprinkles or very light rain showers will occur
along/north of a Jacksonville to Danville line this evening...with
any precip quickly ending from west to east overnight. Once the
cold front passes, winds will veer to the northwest and gust
20-25mph late tonight into Friday morning. Despite full sunshine
on Friday, strong CAA will keep afternoon highs in the 40s.
.LONG TERM...(Friday night through Thursday)
ISSUED AT 301 PM CST Thu Nov 12 2020
High pressure will quickly shift east of the region, allowing a
warm advection regime to develop by Friday night. Models often
spread clouds/precip into the dry/subsident airmass too quickly in
this type of pattern...and this appears to be the case with the
latest runs. All solutions are beginning to slow the advance of
showers late Friday night, with the 18z NAM now keeping the CWA
mostly dry until 12z Saturday. Have therefore reduced PoPs
considerably, with only low chance toward dawn along/southwest of
a Canton...to Lincoln...to Effingham line. There had previously
been some concern that the precip could possibly begin when
surface temps were near or even slightly below freezing, but that
scenario seems much less likely now...as the precip will be
delayed and temperatures will be rising overnight due to
increasing southerly flow. Have therefore kept all precip in the
form of rain. As the atmosphere moistens and WAA strengthens, rain
showers will become widespread across central and southeast
Illinois on Saturday. A cold front is progged to push into the
area during the evening, and with modest MUCAPE values of
100-300J/kg, cannot rule out a few rumbles of thunder at that
time. Once the front passes, dry conditions and seasonable
temperatures will return for the remainder of the extended
forecast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 545 PM CST Thu Nov 12 2020
A cold front will push through central Illinois tonight, reaching
near PIA/SPI between 03z-05z and CMI/DEC between 06z-08z. A few
showers will accompany the front...mainly north of the I-74
corridor. Have continue to mention VCSH at KPIA/KBMI/KCMI between
02z and 09z, but most areas will likely only see sprinkles due to
very dry air ahead of the cold front. Main aviation forecast
challenge will be potential for low ceilings immediately behind
the front. Latest satellite imagery shows an area of MVFR ceilings
across central Iowa and these may swing into central Illinois
later tonight. The latest HRRR forecast has diminished the
coverage of MVFR cigs in our CWA behind the front, but upstream
OBS lend enough support to continue MVFR at KPIA after 05z and
farther east to KCMI after 09z. Farther south, have maintained VFR
ceilings at both KSPI and KDEC through the entire period. Winds
will initially be E/SE at around 8kt early this evening, then will
veer to W/SW toward mid to late evening...then will veer to the
NW and gust 18-22kt late tonight into Friday morning after FROPA.
The surface high center will advance into Illinois Friday
afternoon, bringing clear skies and winds diminishing to less than
10kt.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SYNOPSIS...Barnes
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Shimon
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
536 PM CST Thu Nov 12 2020
.SHORT TERM... (Through Late Friday Night)
Issued at 247 PM CST Thu Nov 12 2020
Currently, water vapor imagery shows a shortwave digging into the
Central Plains and heading toward the Midwest. This shortwave will
send a cold front through the CWA this evening into the overnight
hours. Weak echoes have been noted along this front this afternoon
across northwestern MO and southeastern IA, and there may be the
potential for echoes to occur over our CWA late this afternoon and
evening as this front pushes through. Additionally, cloud cover and
weak echoes are currently also showing up across southwestern and
southern MO pushing eastward associated with the nose of a small
H850 jet and weak area of warm air advection. With a 20-30 degree
spread in surface temperatures and dew points, as well as RAP
soundings showing a rather dry lower atmosphere across the CWA, I
continue to have confidence that this activity will remain weak and
likely not overcome the dry air to reach the surface. Therefore, I
am maintaining a dry forecast, but I could not completely rule out a
rogue sprinkle or two and some virga late this afternoon and
evening. The only other notable weather with this front will be
winds shifting to out of the northwest and gusting around 20-25 mph
overnight.
An area of high pressure will settle into the Middle Mississippi
Valley tonight behind the front and keep our weather cool and calm
through tomorrow. Low-level cold air advection will drive
temperatures down into the mid-30s to mid-20s for overnight lows and
mid-40s to near 50 tomorrow for highs - about 10 degrees below
normal for this time of year. This surface high will quickly depart
the Middle Mississippi Valley to the east tomorrow evening,
returning southerly flow to the CWA ahead of the next system.
Elmore
.LONG TERM... (Saturday through Next Thursday)
Issued at 247 PM CST Thu Nov 12 2020
The first higher chance of rain will occur early Saturday morning
through mid-day. During this part of the period, upper-level
divergence and lift from an approaching shortwave will be coincident
with a low-level jet bringing warm, moist air into the CWA. This
initial area of rain will be focused on the broader I-44 corridor in
MO and I-70 corridor in IL. The chance of rain will wane somewhat
during the afternoon, but ramp up again ahead of a second stronger
shortwave and approaching cold front Saturday evening. Enough
instability will be available for isolated thunderstorms to occur
with this FROPA. While bulk shear will be on the order of 50+ kts,
the limited levels of instability currently forecast will keep the
threat of severe thunderstorms out of the CWA. The front and precip
will clear the CWA late Saturday night into early Sunday morning.
As for rain totals, both NAEFS and EPS guidance have PWAT values of
nearly an inch over the CWA on Saturday - around the 90th percentile
of climatological norms. With this level of moisture in place
between these two events, QPF totals approach 1 inch along the I-44
corridor in MO and I-70 corridor in IL with amounts diminishing to
around a half inch northwestward and southeastward in the CWA.
Behind the front on Sunday through the remainder of the period,
northwest flow aloft will hold over the Middle Mississippi Valley.
At the surface, weather across the CWA will be dictated primarily by
high pressure, keeping conditions calm and dry. Temperatures
gradually increase through the end of the period, but there is much
spread among ensemble and blended guidance on exactly how warm or
cool we will be. Part of this is most likely due to differences in
placement and timing of a dry frontal passage seen in deterministic
models in the Tuesday-Wednesday timeframe. Current forecasted
temperatures are roughly mean values, and WPC cluster analysis shows
that more members favor these mean values or a slightly warmer
solution, so I have confidence in the currently forecasted values
for now. One thing that the ensembles do agree on is a dry period
from Sunday morning through Thursday.
Elmore
&&
.AVIATION... (For the 00z TAFs through 00z Friday Evening)
Issued at 527 PM CST Thu Nov 12 2020
With VFR conditions expected to prevail through the forecast
period, the primary concern is the dry cold front that is
currently pushing into NE MO and west-central IL. This front will
cause winds to quickly pick up and swing around to the northwest.
Fortunately no rain is anticipated due to very dry near-surface
air, though a few sprinkles cannot be ruled out.
A secondary concern is a band of MVFR clouds behind the front
stretching from Wisconsin into NW MO. The vast majority of
guidance shows this band of clouds breaking up as it moves into
the mid-Mississippi Valley, so I`ve left it out of the TAFs for
the time being. That said, we`ll be keeping a close eye on it
through the night and on the off chance it stays together longer
than expected, MVFR cigs could be possible at the terminals,
especially UIN.
BSH
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
636 PM EST Thu Nov 12 2020
.SHORT TERM...(This evening through Friday)
Issued at 310 PM EST THU NOV 12 2020
Water vapor satellite shows a positively tilted northern stream
short wave digging into the Upper Mississippi Valley this afternoon.
SPC Mesoanalysis shows a band of low-level fgen through Iowa,
southeast Minnesota, Wisconsin, and nudging into the western U.P. A
band of snow has persisted for much of the day as this front has
pushed eastward through Minnesota. As the aforementioned wave
becomes neutrally tilted this evening, mid-level Q-vector forcing
will increase over the Upper Great Lakes leading to an increase in
frontal precip for the central and eastern U.P. Therefore, expect to
see rain/snow fill in across the central U.P. over the next couple
of hours. Temps warmed into the mid to upper 40s over much of the
central and east today, so precip will initially fall in the form of
rain, then change over to snow from west to east. Expect that
changeover to occur around 01-03z for most of Marquette County, and
all of the CWA to be seeing snow by about 08z. Moisture ahead of the
front is not particularly impressive, but there should be enough
forcing to squeeze out around 0.1-0.25" of precip for most areas,
which after the start as rain will translate to around 1-2" for most
areas along and east of a L`Anse to Watersmeet line (a little less
along the Lake Michigan shoreline).
The only tricky spot will be across the eastern U.P. where SW flow
ahead of the front will provide some additional lake-enhanced
moisture. The HRRR and a few other CAMs show a strong Lake Michigan
lake-effect band nosing up into Manistique and Newberry. Not
confident in that exact placement (or even if it occurring at all
since lake-effect parameters are awfully marginal) so smoothed out
the QPF somewhat. However, if such a band were to form, and the
changeover to snow were to occur an hour or two sooner than
expected, could see a surprise couple of inches in these areas. This
will be something to watch this evening as the front nudges closer.
Tomorrow, 850 mb temps will drop to around -12 C behind the front
which will support some lake-effect snow showers in the NW wind LES
belts. However, models show moisture scouring out pretty quickly, so
not expecting anything robust. Only expect another half inch of snow
after 12z tomorrow, and only in the typical spots for NW flow.
Regardless of the snow, it`ll be cooler tomorrow with highs likely
not cracking freezing for much of the area, and only making it into
the mid 30s south & east.
.LONG TERM...(Friday night through Thursday)
Issued at 403 PM EST THU NOV 12 2020
A dome of surface high pressure over the southern Great Lakes will
be in place for the early part of Saturday due to upper level
ridging taking place. The lower levels will warm nicely and mix down
to the surface on Saturday, allowing temperatures to rise quickly as
well on the order of potentially 10-15 degrees higher in comparison
to Friday afternoon highs. The WAA regime will be taking place ahead
of a developing mid-latitude cyclone across the central CONUS/Great
Plains area Saturday afternoon further upstream of the CWA. The
GFS/NAM/EURO are hinting at a merger of sorts with two separate
surface Lows combining between early Saturday and late Saturday
night. Currently looks to be a the Polar Jet and Subtropical Jet
enhancement near one another causing the surface Low to deepen over
the Great Lakes. The GFS and NAM have swapped solutions over the
last 24 hours between previous 12Z runs. The GFS now has a 979mb
surface Low by 0Z Sunday evening, whereas the EURO is advertising a
984mb surface low. Both Low centers will deepen the most over
Ontario. Presently, the analysis is showing rain as the main
precipitation type to start the weather event over the CWA, with the
surface cold front bringing the colder air behind it. This will
transition the cold rain to a mixed bag of precipitation, and then
switching to light snow showers by Sunday night into Monday. Models
have backed off on the potential for heavier snow totals, but lake
effect may still be something to keep an eye out for once we get
closer to the weekend where the high resolution guidance can assist
with a forecast package. Euro model hinting at lingering snow
showers through Tuesday morning. From there, upper level ridge
begins to take hold and create a quiet weather pattern with warmer
temperatures starting Wednesday of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 636 PM EST THU NOV 12 2020
Conditions will improve slightly at KIWD this evening as lake-effect
snow showers begin to transition into the area. However, cigs for
KIWD should remain in MVFR due to lake-effect clouds until tomorrow
morning as the lake-effect ends in Ironwood. Conditions at KCMX will
remain in IFR for the next couple hours as the cold front pushes
through. However, behind this front, expect slightly improved
conditions as snowfall transitions to lake-effect snow (instead of
being caused by the cold front). Cigs will remain MVFR until the
afternoon when the lake-effect snow/clouds die off. KSAW`s
conditions will quickly deteriorate over the next couple of hours as
the cold front pushes through. Expect rain initially, then a
transition to snow over the next couple of hours. As the precip type
changes, expect conditions to drop to MVFR, then IFR tonight. Late
tonight, expect conditions to improve to MVFR, as only lake-effect
clouds will remain behind the cold front. By the end of the TAF
period tomorrow, expect all terminals to return to VFR conditions;
KSAW and KIWD will return to VFR conditions by mid-morning tomorrow.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 403 PM EST THU NOV 12 2020
A cold front will pass over Lake Superior this afternoon. Behind the
front, winds remain near 20 knots across the west and 25 to 30 knots
across the east through midday Friday. High pressure will bring
generally calm winds through Saturday morning below 20 knots, but a
developing storm system will approach the Upper Peninsula, winds
increase from the south to around 30 knots across the east half of
Superior Saturday afternoon through Sunday morning. An associated
cold front passes over the lake Sunday as winds veer to the NW,
increasing to gales to around 40 knots across the east and 35 to 40
knots across the west. These gales persist across the east half
through Monday afternoon, before falling into the low 20-knot range
Monday night for the east half through the rest of the fcst period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...RJC
LONG TERM...BW
AVIATION...TAP
MARINE...BW
Area Forecast Discussion
National Weather Service Pendleton OR
630 PM PST Thu Nov 12 2020
.UPDATE...Changes were made to the forecast to add wind
advisories for the Lower Columbia Basin, Blue Mtn Foothills, the
Kittitas and Yakima Valleys, Simcoe Highlands, the eastern
Columbia River Gorge, and North Central Oregon. Areas of blowing
and drifting of snow was also added to the mountain zones.
Although models have backed off on the winds compared to several
days ago, the tight pressure gradients will cause very windy
conditions to develop in the advisory areas. HRRR and other high
resolution models are showing 10m winds around 25 kts, and there
are hints of isentropic descent that could bring 50kt winds at
850mb near the surface. No changes were made to the current winter
storm warnings and winter advisories. Wister
&&
.PREV DISCUSSION... /issued 223 PM PST Thu Nov 12 2020/
SHORT TERM...Tonight through Saturday...A weather system will move
into the area overnight initially as a weak warm front followed by a
cold frontal passage on Friday. This system will bring some
significant snow accumulations in the mountains where winter warning
and advisories will be in effect. Will also see some increasing
southerly winds overnight warranting a windy advisory for the
southern Grande Ronde Valley. There could be some blowing and
drifting snow issues late tonight and early Friday in the southern
Grande Ronde valley. The cold frontal passage Friday will bring some
breezy to windy conditions across the entire forecast area through
Friday night then decreasing slowly Saturday. Precipitation will
taper off to showers Saturday mainly over the mountains. Another
system will arrive from the west late Saturday and overnight as a
warm front. Precipitation will be snow above 2000-3000 feet
initially Saturday afternoon and then rising overnight especially in
central Oregon. Still there will be some more snow accumulation
before changing to rain going into Sunday. More highlights may be
needed for this event but will hold off on any until current
highlights have ended.
LONG TERM...Sunday through Thursday...models in fairly good
agreement for the long term. Moist westerly flow for Sunday with
mountain rain/snow showers expected with mainly dry and locally
breezy conditions in the basin. Highs 40s to low 50s. Rain and high
mountain snow chances increase Sunday night into Monday with strong
warm air advection over the region and plume of deep Pac moisture
working onshore and lifting north. Precip expected to end south to
north Monday night as ridging builds in. Flow turns more southerly
on Tuesday as the ridge shifts east as another upper level
trough/low approaches the coast. Mild temps for Mon/Tue with highs
generally in the 50s. Some breezy southerly winds possible, esp in
the Grande Ronde valley and the foothills of the Blues/Wallowas. The
next system is expected to impact the region Wednesday into
Thursday. Models showing mainly rain and high mountain snow
overspreading the region Wednesday afternoon as deep Pacific
moisture working from the south and front passing through. Precip
expected to become more showery Thursday into Friday as the upper
trough is expected to work overhead. Snow levels remain fairly high
only expected to drop down to 4000-5500ft. Slightly cooler Wed/Thu
with highs in the mid 40s to lower 50s.
AVIATION...00Z TAFs...VFR conditions with increasing mid to
high level cloudiness today. Winds will be less than 10kts as well.
An approaching system will overspread showers tonight with light to
moderate rain expected for most of tomorrow. MVFR conditions
possible, esp as CIGS drop down to 2-3kft. Mountain obscuration
likely. Winds will increase 16-22g24-30kt tomorrow. Pockets of
strong low-level wind shear possible starting late tonight, esp near
BDN/RDM and PDT.
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 37 51 35 47 / 60 90 30 10
ALW 38 51 37 49 / 60 90 40 10
PSC 39 54 39 52 / 50 60 20 10
YKM 32 51 32 50 / 30 60 20 10
HRI 38 55 39 52 / 40 70 20 10
ELN 29 45 31 44 / 40 60 30 10
RDM 35 49 30 44 / 20 90 60 40
LGD 32 42 31 40 / 40 100 70 30
GCD 35 43 30 38 / 30 100 70 40
DLS 39 51 39 50 / 50 90 50 30
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Storm Warning until 4 AM PST Saturday for ORZ509.
Wind Advisory from 4 PM Friday to 4 AM PST Saturday for ORZ041-
044-507-508-510.
Winter Weather Advisory from 10 PM this evening to 4 AM PST
Saturday for ORZ049-050-506.
Winter Storm Warning from 10 PM this evening to 4 AM PST
Saturday for ORZ502-503.
Wind Advisory from midnight tonight to 3 PM PST Friday for
ORZ049.
WA...Winter Storm Warning until 4 AM PST Saturday for WAZ520.
Wind Advisory from 4 PM Friday to 4 AM PST Saturday for WAZ024-
026>029-521.
Winter Storm Warning from 10 PM this evening to 4 AM PST
Saturday for WAZ030.
&&
$$
SHORT TERM...85
LONG TERM....84
AVIATION...84
AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
820 PM EST Thu Nov 12 2020
.SYNOPSIS...
A cold front will push east to the coast tonight. Another cold front
will move across the region late Friday. High pressure will build
into the region for late Friday and Saturday. Another cold front
will move across the region late Sunday.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 820 PM Thursday...
The heavy precip has shifted just E of the forecast area, in
conjunction with the leading cold front. A secondary W-E backdoor
boundary, noted on 0.2 deg radar imagery dropping southward through
the Triangle (and having pushed just south of the Triad), is
accompanied by a surge of gusty northeasterly winds and designates
the leading edge of the cooler and drier air, with temps/dewpoints
quickly dropping up to 10 deg behind the boundary. This front should
continue its southward push through NC tonight, although it may slow
or stall across our E and S depending on the influence of TS Eta as
it tracks northeastward just off the Carolina coast tonight/Fri.
GOES water vapor imagery shows much drier air aloft over W and
central NC and across much of SC (W and SW of Eta), although
considerable moisture persists below about 750 mb, leading to patchy
light rain and drizzle in recent hours across our N and W. The
recent runs of the HRRR show this continuing overnight, especially
across the N and W CWA, so have added this to the forecast, with low
overcast skies. While no substantial additional rainfall will occur
for the remainder of the night, spotty residual flooding issues
persist over the area. Will continue areal flood warnings to account
for the lingering hazardous travel, particularly on roads near
swollen creeks. Numerous river flood warnings remain in effect as
well (see hydrology section below). Expect lows to range from around
50 far NW to upper 50s SE. -GIH
Earlier discussion from 300 PM: A deep plume of tropical moisture
combined with an approaching upper-level trough, a cold front and an
associated mid-level fgen and robust divergence aloft resulted in a
widespread area of moderate to heavy rain that moved across central
NC during the past 24 hours. Storm total rainfall amounts will
generally average between 2 to 5 inches across the western Piedmont
including the Triad with some locally higher. East of U.S. Route 1
across the Triangle, Coastal Plain and Sandhills, amounts will
average between 4 to 8 inches with a few locations across the
northern Coastal Plain, along and east of I-95 exceeding 10 inches.
As of mid afternoon, the cold front has pushed south and east of the
RAH CWA with surface dew points ranging in the lower to mid 60s in
central NC. The back edge of the main shield continues to push east.
The widespread rain will end shortly at KRDU and it should end near
KRWI and KFAY by 4pm. The very heavy rain has resulted in widespread
reports of flash flooding, road closures, and water rescues across
much of the area. Even though the steady/widespread rain has ended
in the Triad and should end soon in the Triangle, the threat from
continued run off and flooding will persist. See the hydrology
section below for more information.
While the widespread rain should be over across all of central NC by
around 5pm, widespread clouds are expected to continue into the
overnight with perhaps some areas of spotty light rain or drizzle
this evening, especially across the east. A northeasterly low level
flow and the transport of cooler air will result in lows falling
into the lower to mid 50s by Friday morning. -Blaes
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
As of 310 PM Thursday...
Widespread clouds are expected to start the day on Friday as an in-
situ CAD airmass will be established across the area. The stable air
mass will initially weaken during the morning and then be scoured
out as a secondary cold front moves across the area during the late
morning and early afternoon as the remnants of tropical cyclone Eta
moves up along but just off the coast. Highs on Friday will range in
the upper 60s to lower 70s. Lows on Friday night will range in the
lower to mid 40s but some of the typically cooler locations will
have some lows in the upper 30s. -Blaes
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 230 PM Thursday...
Highlights of the long term include...
- Slight chance of showers on Sunday.
- Much cooler early to mid-next week.
- Patchy frost possible in the mornings next week.
Saturday: Upper-level ridging over FL will create west to
southwesterly flow aloft across the region. Surface high pressure
over the Ohio Valley will build east throughout the day and off the
Mid-Atlantic Coast by Saturday night. This will switch northerly
surface flow to easterly by the end of the day, and help increase
dewpoints from the 30s up to the 40s. Highs will be in the 60s due
to weak cold air damming, and lows will be in the 40s.
Sunday: Upper-level high pressure to the south will weaken as an
upper-level trough moves across the Mid-Atlantic throughout the day.
A lack of moisture and instability will keep the majority of rain to
our north, however isolated showers could move across the northern
Piedmont and northern Coastal Plain. The surface cold front will
move across the region Sunday night and begin cold air advection
over the area as winds switch from southwesterly to northwesterly.
Highs will be in the mid-60s to mid-70s, with highest temperatures
across the SE due to warm air advection ahead of the front. Lows
will be in the 40s.
Monday through Thursday: NW flow aloft will persist through the
period, with a slight increase in heights each day as upper-level
high pressure builds from the Desert Southwest to the Southeast.
This will create dry weather across the region for early to mid-next
week. Surface high pressure over the lower Mississippi Valley will
expand across the East Coast early next week, maintaining cold air
advection across the region. The high then weakens Tuesday as
another surface high builds from the Northern Plains into the Ohio
Valley, helping to maintain cold air advection into central NC.
Highs will be in the 50s through the period, and lows in the mid to
upper 30s will create patchy frost in the early mornings.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 740 PM Thursday...
Currently all terminals are sub-VFR as the heavy showers have exited
the region. There still remains a few lingering light showers over
the area. Tonight, conditions are expected to remain sub-VFR through
daybreak Friday and will improve to VFR conditions with some high
cirrus clouds by afternoon. Low stratus and some fog will continue
into the overnight and early morning hours. Winds overnight will be
light and NE then becoming NW and a bit stronger (5-10kts) by late
morning. Wind gusts in the Southeast and along the Coastal Plain
will be 10-15kts in the afternoon dying down by the evening.
Outlook: High pressure will build into the region for the weekend
with fair weather and VFR conditions. A cold front will move across
the region Sunday into Sunday night with a limited chance of a
shower and perhaps some MVFR ceilings. Otherwise, fair weather is
expected into early next week. -Blaes
&&
.HYDROLOGY...
As of 320 PM Thursday...
Significant rainfall occurred across central NC over the last
24-48 hours. As of 2pm, amounts have ranged from 3 to 5 inches
over the Triad, with Greensboro Intl Apt receiving 4.10 inches.
Further east across the Piedmont and into the Triangle, 3-4
inches have been reported, with 4.18 inches here at our NWS
office at NCSU and 2.97 at RDU. The highest amounts have been
across the eastern Piedmont and Coastal Plain, especially
along/east of I-95, with Rocky Mount Wilson Airport reporting
9.40 inches over the last 48 hours.
The impressive rainfall totals has resulted in widespread river
flooding. Minor flooding has already been occurring along the
Neuse, Tar, Haw, Deep, and the Yadkin rivers. Additional
flooding is expected downstream along these basins and at the
Roanoke and Cape Fear basins. Major flooding is expected to
occur on the Haw and Neuse river basins.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Blaes
NEAR TERM...Hartfield/Blaes
SHORT TERM...Blaes
LONG TERM...JT
AVIATION...CA/Blaes
HYDROLOGY...ACK