Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/29/23
Area Forecast Discussion
National Weather Service Boston/Norton MA
938 PM EST Sat Jan 28 2023
.SYNOPSIS...
Above normal temperatures continue into Sunday, along with mainly
dry conditions, until Sunday evening when scattered showers impact
the region. The weather turns colder next week, but the magnitude of
the cold and timing remains uncertain. We also will have to watch
for some wintry precipitation in the mid-to-late week timeframe,
depending upon a few waves of low pressure passing close to our
region.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
930 PM update...
Temperatures running a bit cooler than initiall forecast across
northwestern MA. Have updated the near-term to reflect this
trend with HRRR guidance which has a good grasp on the current
temperatures over that area. Otherwise, the quiet forecast
remains on track and no additional changes are needed.
Previous Discussion...
* Above normal temps again tonight
Tonight...
Tranquil January weather this evening and overnight, as weak ridging
advects across the area. The combination of weak high pressure,
partly cloudy conditions and a dry airmass (dew pts in the 20s away
from the south coast) will allow temps to cool off rapidly with
sunset, especially with diminishing winds. Some uncertainty how low
temps will get tonight, pending how much cloud cover moves across
the area. Given this uncertainty, blended in some of the colder MOS
guidance to derive overnight lows, which yields 20s mainly northwest
of I-95, and low to mid 30s elsewhere. Still above normal for late
January.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
345 PM update...
Sunday...
* Late March-like temps again
Low pressure moving thru western NY into northern New England will
drive another warm sector into SNE Sunday. Even warmer 925 mb
temps, +4C Sunday vs +1C Saturday. Thus, potentially warmer Sunday
but also possibly more clouds than today. Although, this time of
year with low sun angle, temps more driven from thermal advection
than solar insolation. Therefore, we blended in some of the warmer
NBM 75 percentile temps. This yields temps slightly milder than
today, with highs 50-55, upper 40s along the immediate south coast
and high terrain. Again, well above normal, about 15-20 degs! More
typical highs for late March. Although, it will feel cooler given a
brisk SSW wind 15-25 mph. Dry weather much of the day, but risk for
scattered showers late as weak short wave and associated cold front
approach the area.
Sunday night...
Weak cold front and associated low level SSW jet, providing modest
thermal and moisture advection, including low level convergence,
likely sufficient for scattered evening showers. Although, given
deep layer moisture is limited along with weak synoptic forcing,
some areas may remain dry. Thus, not a washout. Breezy and mild in
the evening in response to low level WAA, then weak post frontal CAA
brings temps down into the 30s regionwide overnight. Once again,
above normal for late Jan.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
345 PM update...
Highlights...
* Mostly dry this week with periodic shots of light precipitation
* Potential for much colder air toward the end of the week, but
details are uncertain.
Details...
Overall a quiet, generally zonal weather pattern for the coming work
week. Southern New England will be positioned between an upper level
ridge of high pressure over the Caribbean and a trough over eastern
Canada. Given the setup we`ll stay dry save for a few disturbances
mixed in. The first comes Monday night into Tuesday when a shortwave
and surface cold front swings through kicking off some light, high
elevation snow and low elevation rain. Behind that cold front a
cooler airmass moves in and temperatures previously well above
normal (in the 40s and low 50s Monday) will crash back to Earth. 850
mb temps around 0C for the weekend into Monday will drop to anywhere
from -8 to -15C Tuesday through at least Thursday. This brings us
afternoon highs in the 30s. A true surge of colder arctic air is
possible around Friday into the weekend as deeper trough digs into
the eastern seaboard. Timing and magnitude remain uncertain, but the
global guidance indicates those 850 mb temps dropping up to another
15 degrees, as cold as -25 or -30C. We`re not expecting a prolonged
arctic intrusion, but a brief shot at much colder air is possible at
the end of the week. A low passing to our south on Thursday may
bring wet weather but ensemble probabilities of this coming close
enough to impact southern New England are low.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
00z update...
Tonight...High confidence.
SKC, then VFR cloud bases entering northwest MA late. WSW winds
10-15 kt at 00z, then becoming light south late.
Sunday...High confidence.
VFR cloud bases, but MVFR cigs late northwest MA. Chance of
scattered rain showers toward 00z. Light south winds in the
morning become SSW winds in the afternoon, 15-25 kt.
Sunday night...high confidence.
VFR cloud bases, with MVFR cigs across northwest MA. Chance of
scattered showers 00z-06z, then drying out and trending toward
VFR 12z. SSW winds 15-25 kt at 00z, shift to west after 05z and
diminish to 5-10 kt.
KBOS Terminal...High confidence. Gusty WSW winds diminish
20z/21z, then become light WSW.
KBDL Terminal...High confidence.
Outlook /Monday through Thursday/...
Monday & Monday night: Breezy. Slight chance RA.
Tuesday: Breezy.
Tuesday Night: Slight chance SN.
Wednesday: Breezy. Slight chance SN.
Wednesday Night through Thursday: Breezy.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
345 PM update...
Through Sunday night...
Tonight...high confidence.
Gusty SW winds 15-25 kt near shore this evening, diminish and become
light south overnight. Dry weather and good vsby.
Sunday...high confidence.
Light south winds in the morning, becoming SSW 15-25 kt in the
afternoon. Dry weather and good vsby, although low risk of scattered
showers late in the day.
Sunday night...high confidence.
SSW winds in the evening of 15-25 kt, becoming west 10-15 kt
overnight. Scattered evening showers, trending dry overnight.
Outlook /Monday through Thursday/...
Monday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Monday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Slight chance of rain.
Tuesday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Tuesday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Slight chance of snow.
Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of snow.
Wednesday Night: Winds less than 25 kt. Seas locally
approaching 5 ft.
Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of rain.
&&
.HYDROLOGY...
345 PM update...
Flood warnings continue for the Pawcatuck River in RI, impacting
Westerly RI, and the Taunton River, impacting Bridgewater in
southeast MA. Both rivers are in minor flood but continue to
recede and will fall below flood stage this evening (Taunton
River) and Sunday afternoon (Pawcatuck).
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 10 PM EST this evening for ANZ250-
254>256.
&&
$$
SYNOPSIS...Nocera/BW
NEAR TERM...RM
SHORT TERM...Nocera
LONG TERM...BW
AVIATION...Nocera/BW
MARINE...Nocera/BW
HYDROLOGY...
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
537 PM CST Sat Jan 28 2023
...Updated 00Z Aviation.
.Discussion...
Issued at 402 PM CST SAT JAN 28 2023
Key Messages:
-Light Wintry Precipitation Tonight
-Cold Temperatures Start Sunday, Continue Next Few Days
-Light Wintry Precipitation Possible Sunday Night
Discussion:
Currently the mid-level flow remains zonal though quite brisk with
H5 winds pushing 100 kts. There is a short-wave perturbation located
over southern Colorado this afternoon that has provided enhanced
lift over the High Plains. A surface low pressure trough extends
eastward into the middle Mississippi River Valley and has allowed a
thermal boundary to develop across the forecast area. For the past
18-24 hours, this boundary has been sitting just north of Hwy. 36.
Weak southerly flow this afternoon has pushed it just slightly
northward. Most of the forecast area remained on the anti-cyclonic
side of the 300mb jet streak this morning with ageostrophic wind
convergence promoting subsidence, and helped to clear out cloud
cover for this morning for a few hours. These few hours of
insolation allowed temperatures south of the surface boundary to
climb into the 50s this afternoon. Weak 290K isentropic ascent did
allow clouds to redevelop this afternoon. RAP soundings did indicate
steep boundary layer lapse rates, though very shallow, and appears
on satellite imagery a few cumulus have attempted to bubble up.
However these are hitting an inversion around 800mb, likely some
overrunning of warmer air with the southerly flow. The boundary
layer has remained dry enough to hold off on precipitation at the
surface, at least for now. While moisture will not be in the highest
supply, there will be enough of it in certain spots to result in
wintry precipitation late tonight through early Sunday.
A secondary short-wave trough coming out of the northern Rockies
will force the strong surface high pressure in the eastern Dakotas
southward this evening and will push the semi-stalled boundary
southward. Low-level convergence increases across northern portions
of the forecast area around 00z this evening and there is some
signal for weak frontogenetical forcing, though most of that is
located on the south side of the boundary. This should be enough to
provide lift from far northeast Kansas into northern Central
Missouri. Drier air coming in from the northern Plains (dewpoints
less than 10F) will greatly limit QPF across this region, and is
also making ice introduction difficult to pinpoint. High resolution
model soundings remain very border line with respect to saturation
through the DGZ and vary from hour to hour. Therefore, expect
precipitation to start as rain, and then eventually transition to snow
as temperatures rapidly plummet as the front is forced well
southward. A period of freezing drizzle or freezing rain is possible
when ice introduction is lost. Overall, accumulations are expected
to be light with just a few tenths of inch of snow in the forecast
across the north, and just a few hundredths of ice. Elevated
surfaces and some roadways, including bridges may become slick
overnight as the temperatures quickly plummet. However, this does
not look to be a widespread enough issue to warrant an advisory at
this point. Although the temperature drops may cause initial concern
for flash freeze, the lack of widespread rain showers and lack of
wet surface preceding the temperature drop will preclude this. By
Sunday morning in northern Missouri, the temperatures will be cold
enough that the surface itself will be in a dendritic growth zone.
There is some question as to whether or not there will be
saturation, but given the stronger convergence, will leave flurries
through Sunday morning. At this point though with dewpoints well
below 0F would not expect enough moisture to create any additional
accumulations.
The second area of wintry precipitation late tonight and into early
Sunday morning will be our southeast counties, essentially from
Henry into Cooper Counties. The main synoptic cold front will be the
main play for this. Low-level convergence increases as the front is
forced southward by the surface high coming out of the northern
Plains. The surface pressure trough elongates and the center of the
cyclone is forced into the lower Mississippi River Valley. In
addition to the convergence, the RAP has continued to depict a
frontogenetical band in the 1000-850mb layer along the boundary
moving southward that will provide enhanced lift through the
evening. As was the issue with the northern area of precipitation,
there is not a whole lot of moisture to work with, and thus lower
QPF, but there is just enough that along with this forcing
precipitation is likely to reach to the surface. Temperatures should
be above freezing at the onset of precipitation, allowing rain to
lead off the night. As colder air moves in, expect a transition to
freezing rain/drizzle, and perhaps light snow. However, recent high
resolution model soundings have substantially backed off of ice
introduction within the DGZ ahead of the main front, which makes the
predominant precipitation type with the colder temperatures either
freezing rain or freezing drizzle. NBM probabilities for freezing
rain/drizzle are above 50 percent, with snow probabilities less than
20 percent along the front. 12z HREF mean is also in agreement in a
transition from liquid rain to freezing rain/drizzle as the colder
air pours in behind the front. Therefore, the forecast currently
reflects a few hundredths of inch of ice accumulations in our
southeast counties this evening. Sleet may also not be out of the
question later this evening as well. RAP/HRRR soundings depict a
warm nose around 950mb around +3.5C with surface temperatures then
rapidly decreasing to near -10.0C. This signal only last for two
hours in these solutions though, therefore would not expect sleet to
last long nor result in any substantial accumulations. As was the
case up north, the temperature changes may cause concern for a flash
freeze event, but given the low QPF, is not expected to materialize
into a widespread issue. The main concern for travel will be any
surfaces that are wet and does not evaporate as the front passes
through with drier dewpoints and northerly wind gusts of 20 to 25
MPH. If this FROPA had been preceded by heavy widespread rain, we
would be dealing with bigger issues. Therefore, given the light QPF
amounts, at this time do not see the need for an advisory.
Adjustments can be made later this evening if heavier rain is
occurring prior to the colder temperatures arriving, but this is not
anticipated at this time. As for the shallow instability noted on
soundings, it is exactly that. Very shallow, and likely will not
have the moisture needed to develop any kind of horizontal
convective roll structure despite the moderate low-level dynamics
with this low pressure and boundary moving through the area. If the
instability were a bit deeper and tapped into greater moisture,
there would be greater concern.
In between these two areas of accumulating wintry precipitation is
the notable dry slot that developed this afternoon from Ottawa, KS
through the KC Metro over to Macon County, MO. This dry slot is the
reason why there is no QPF along this line, despite the strong
convergence that will moving through later this evening. Gusty winds
will accompany the cold front passage this evening, as well as a
rapid decrease in temperatures. Eventually, the DGZ will be very
near the surface. While there is not much saturation, any lingering
convergence with the approaching high pressure system may help to
develop a few dendrites, and therefore may result in some flurries
overnight into Sunday morning. Therefore, have placed light flurries
into the grids. However, the moisture will greatly be lacking, and
therefore no accumulation would be expected, and visibility should
remain above 6 miles.
Sunday Late Morning and Beyond:
Lingering flurries may still be noted late Sunday morning, but the
forcing will be well off to the southeast and therefore will be done
accumulating precipitation. Attention then turns to the cold
temperatures in the morning with breezy winds sending wind chills
below zero across most of the forecast area. Coldest wind chills are
currently forecast in far northwestern Missouri. With strong CAA
continuing into the afternoon, not much relief is expected for highs
on Sunday, reaching only the mid teens across most of the forecast
area. The surface high pressure coming out of the Northern Plains is
progged to become as strong as 1036mb by Monday afternoon. While
this moves into the region, northerly winds will maintain CAA Monday
into Tuesday, leading to cold overnights and mornings through
Tuesday morning. Currently the forecast barely touches Wind Chill
Advisory Criteria across our north, however if we end up with a
night of stronger radiational cooling, some of the forecast area may
reach this. Regardless of criteria or not, temperatures will remain
well below normal through the middle of the week. Relief starts to
arrive Wednesday into Thursday when a short-wave helps to switch low-
level flow southerly and will get temperatures back into the upper
30s and maybe lower 40s. Overall, NBM temperatures have not been
greatly adjusted as values are coming in close the 25th percentile.
However will need to continue monitor trends, as the recent streak
above normal temperatures may allow the bias corrections to sneak
into some of the model guidance.
One final note, there are some signals for weak convergence late
Sunday night in our far southeast again that could result in another
light wintry mix. Overall confidence is low, and most ensembles
remain dry for our southeast counties, but areas along Interstate 44
may see a brief moisture return. If wintry precipitation does creep
up into our southeastern counties, it should be very light and thus
have minimal impacts.
&&
.Aviation...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 535 PM CST SAT JAN 28 2023
A strong cold front is moving through the region rapidly dropping
temperatures and shifting winds to northwesterly. Intermittent
gusts are anticipated through the night reaching around 20-25 kts.
Precipitation chances remain low, although not zero. Any
precipitation is expected to be light with no accumulations at the
terminals. That said precip may start as -DZ/-FZDZ before
transitioning to -SN fairly quickly. Best probabilities for light
precip is after 02-03Z with higher chances north and east of the
terminals ending before sunrise.
MVFR CIGs move in with the front and are expected to stick around
through the period with some lifting of OVC skies toward the tail
end of the period. Some temporary SCT IFR conditions are possible
through the night.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...Krull
Aviation...Pesel
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
520 PM CST Sat Jan 28 2023
...Aviation Updated...
.SYNOPSIS...
Issued at 345 PM CST Sat Jan 28 2023
H5 analysis this morning had a closed low over northern
portions of Hudson Bay. A long wave trough of low pressure was
present over the CONUS and southern Canada. Within this trough a
shortwaves were noted over eastern Ontario, southern Idaho and far
southern Nevada. Another more subtle shortwave was noted over
central Alberta. A strong arctic front passed through western and
north central Nebraska earlier this morning. After readings started
out in the 20s this morning, they have fallen into the upper single
digits to upper teens this afternoon. Skies were cloudy across all
of western and north central Nebraska and very light snow continued
to fall over portions of the Sandhills and north central Nebraska.
Across southwestern into central Nebraska some patchy freezing
drizzle was reported earlier this morning. That has since ended
across the area. Winds were northeasterly or easterly across the
region and wind speeds were generally in the 15 to 25 MPH range
across the area.
Key Messages:
-A long duration, light snow event will continue with two bouts of
snow. The first being mainly this evening then a second from mid
morning Sunday through Sunday night. Highest accumulations with
these two bouts, appear to be over the W Sandhills and eastern
panhandle.
- Dangerous, cold wind chills of -15 to -25 expected tonight with
wind chills of -10 to -20 expected Monday morning and Tuesday
morning.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 345 PM CST Sat Jan 28 2023
Tonight through Sunday night...The main forecast challenges in
the near term are temperatures and the threat for light snow.
Light snow continues to fall across the Sandhills and northern
Nebraska this afternoon. Visibilities were generally in the 1 to 5
mile range. The threat for light snow will continue and shift to
the south this evening. The latest NAM12 and GFS solns indicate
weak lift in the dendritic layer mainly this evening. As for
QPF`s: After chatting the WPC, got them to increase QPF`s over
their pvs forecast with this package. This brought QPF`s more in
line with the 12z Canadian and GFS solns, but still lower than the
12z NAM12 and HRRR solns which were on the high end of the
models. Utilizing a roughly 18:1 ratio, there will be the
potential for around an inch of additional snow this evening. Lift
weakens temporarily overnight with a secondary shot of weak lift
arriving Sunday morning into Sunday evening. QPF`s will be a few
hundredths up to a tenth of an inch with this second episode, so
snow accums of 1 to 2 inches are possible. Total accumulations of
1 to 3 inches are possible from tonight through Sunday evening.
Given the long duration of light snow and limited winds, will
forgo extending any snow headlines beyond the current winter storm
warning and advisory. With respect to wind chills tonight: Not
much changed with lows and winds with this forecast package so the
current wind chill advisory is on track as is. I did go ahead and
add Hayes county to the advisory tonight as their wind chills
tomorrow morning flirt with -20. Wind speeds will fall during the
day Sunday and continue to fall Sunday night. This will lead to
warmer minimum wind chills compared to tonight. However, skies are
expected to scatter out, particularly over northern Nebraska by
Monday morning. This will allow lows to fall down to -10 below
zero in northern Nebraska. Even with the light expected winds,
minimum wind chills may fall off to around -20 Monday morning in
the north. Will re-assess this in the next one or two forecast
cycles and issue any wind chill headlines at that time.
.LONG TERM...(Monday through Saturday)
Issued at 345 PM CST Sat Jan 28 2023
The threat for flurries/very light snow, will linger in the west
Monday morning. At the same time, a trough of low pressure will
deepen along the west coast of the CONUS, diving south into
southern California Monday night. As this feature tracks along the
US/Mexico Border Tuesday into Wednesday night, ridging will
develop across the central and northern Rockies. Warmer air will
be forced into the forecast area Thursday into Friday. EC H85
temps reach 4 to 8C across the area Friday. Normally, would feel
confident in 40s for highs if this verifies, however with
widespread snow cover, the NBM forecast of 30s appears on track
attm. The GFS and EC solns drive a mid level shortwave trough
across the central plains Saturday. ATTM, not expecting much in
the way of pcpn. with this feature.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 519 PM CST Sat Jan 28 2023
Polar air will continue to build into wrn and ncntl Nebraska
tonight through Sunday afternoon and light snow will accompany
the cold air leading to periods of MVFR/IFR ceilings and vsby.
This flight concern is expected to be most prevalent along and
west of highway 61.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 PM CST /5 PM MST/ this evening
for NEZ004-005-025>029-094.
Wind Chill Advisory until noon CST /11 AM MST/ Sunday for
NEZ005>010-024>029-036>038-059-070-071.
Winter Storm Warning until 6 PM CST this evening for NEZ006>010.
&&
$$
SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...CDC
Area Forecast Discussion
National Weather Service Blacksburg VA
950 PM EST Sat Jan 28 2023
.SYNOPSIS...
Widespread rain will spread across the area on Sunday as a cold
front approaches the region and a low pressure system crosses
the southeast United States. Periods of rain will continue for
much of the week, with a high probability of precipitation on
Tuesday through Thursday. Any threat of winter precipitation is
limited.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 945 PM EST Saturday...
...Clouds increase overnight with rain arriving tomorrow
morning in the west...
Satellite imagery shows increasing high clouds across the area
tonight. Expecting clouds to build in overnight and lower as low
pressure forms and deepens over the TN Valley. Timing of PoPs
and amount of QPF still look reasonable for train spreading/
developing across the region Sunday morning and continuing
through the day. Overnight lows will be in the low to upper 30s,
with ridges being a bit warmer, and the lowest temperatures
occurring early tonight before clouds build in and keep
temperatures more steady.
As of 640 PM EST Saturday...
High confidence of rain on Sunday...
High cirrus clouds are moving across the area, mostly along
southern VA and northern NC, ahead of the cold front approaching
the Mid Atlantic from the west. Expect cloud cover to increase
through the overnight hours, and overcast skies by Sunday with
widespread coverage of rain. No significant updates made to the
forecast for this evening`s update, adjusted cloud cover and
blended in temperature observations. Otherwise, forecast remains
on track.
Previous discussion below...
As of 120 PM EST Saturday...
Models were in good agreement with the synoptic scale weather
pattern tonight and Sunday. A cold front will move toward the
area from the northwest but with broad, persistent west-
southwest flow aloft the front and any cold air remain north of
the region. At the same time a low pressure system crosses the
southeast United States providing a deep layer of isentropic
lift and moisture all the way into the Mid Atlantic region.
High clouds fill in this evening with the cloud bases lowering
overnight. The atmosphere will be saturated enough to support
rain on Sunday. Timing of the rainfall is where smaller
differences show up in the models. The 3KM NAM, RAP, and HRRR
were used for when rain begins and spreads east. Bufkit forecast
soundings and the SPC HREF have the rain only reaching Danville
and points east and south by the end of the day.
Cloud cover will limit temperature drop tonight and much warming
Sunday. Surface dew points rise into the mid to upper 30s by
late Sunday. Will trim a couple of degrees off the high
temperature Sunday.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 200 PM EST Saturday...
Decreasing precipitation chances Sunday night into Monday but
increasing again by Tuesday and Tuesday night...
A frontal boundary will be positioned across the area Sunday
night and heading east. Just how quickly associated rain exits
the region will depend upon the influence of a shortwave trough
over the Southeast US. This feature has the potential to both
stall the front, and advect its own light rain across southeast
portions of the forecast area. Our forecast will reflect this
potential with small chances of rain lingering across the far
southeast sections through Monday morning. Across the west, a
bit of an upslope component will help maintain some isolated
rain showers across portions of Southeast West Virginia through
Monday afternoon.
The break in precipitation will be short lived. As we progress
from late Monday night into Tuesday, eyes turn southwest with
the advance of another shortwave trough. This one will cross the
area on Tuesday and exit Tuesday evening. On its heels will be
yet another system that could starting bringing its associated
precipitation into the area late Tuesday night. Model guidance
varies on the degree which there may be a break in the
precipitation between the two systems. For now, our forecast
will not reflect a stop in the precipitation, but a period of
lower probabilities Tuesday evening.
The precipitation type Monday night through Tuesday night at
this point will be handled with a rain versus snow forecast
given the uncertainties in the low level thermal profile. The
best chance for wintry weather will be across Southeast West
Virginia and potentially portions of the neighboring counties of
Southwest Virginia, especially during Tuesday night.
Temperatures during this portion of the forecast are expected to
average 15 degrees above normal on Monday and 5 to 10 above
normal for Tuesday.
Confidence in the above weather scenario is moderate with
precipitation timing and p-type the biggest question marks.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 1215 PM EST Saturday...
Precipitation is possible for the second half of the week with
timing and coverage of this precipitation still a question
mark...
Model guidance is offering a solution during this portion of the
forecast period for a frontal system to be stalled at least
Wednesday through Friday over, or just southeast of the region.
Additionally, a number of southern stream shortwave troughs are
expected to ride along this frontal boundary, bringing rounds of
precipitation to the areas they pass over or near. The
challenges with this part of the forecast are two fold. First,
each model offers different answers on where this front will be
each of these days. Secondly, there are differences on the
timing timing and location each of the southern stream
precipitation makers.
Our forecast will continue to favor the national blend of models
as a consensus forecast. This solutions places the greatest
coverage of precipitation across our area early Wednesday
morning and late Wednesday night through Thursday. In between
these two time frames precipitation chances remain at least the
chance category for much of the region. After Thursday night, we
will be offering decreasing chances with the premise that the
front will start to be exiting the area to the east.
Most of the guidance offers a dry forecast by Saturday except
for the Canadian solution. Its guidance allows for one
additional southern stream system to buckle the front back
across the area on Saturday. With the majority of the solutions
dry and cooler, will only entertain a slight chance for
Saturday.
Precipitation types during the forecast period are equally
challenging as the low level thermal profile varies notably from
model to model. At this this time, we will over a rain versus
snow forecast solely on the forecast surface temperature, with a
lower than typical cutoff temperature for the rain/snow mix of
34 degrees. Above 34 will be plain rain, and 32 or below will
yield a snow forecast.
Temperatures across the area will be highly dependent upon where
the front establishes itself and how much, and where,
precipitation falls. However, our forecast as an average will
offer forecast high temperature near normal through the period,
with low temperatures a few degrees above normal Wednesday night
and Thursday night and near normal lows Friday night and
Saturday night.
Confidence in the above weather scenario is low given the
challenges mentioned above.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
As of 635 PM EST Saturday...
Currently, VFR conditions are observed across the area, and
will remain VFR until Sunday morning, about 12Z/7AM, when rain
will begin and spread from west to east. High cirrus clouds are
moving across northern NC and southern VA. Cloud cover will
start to increase and ceilings will start to lower overnight
Saturday and early Sunday morning as the rain approaches.
Most of the area will see rain, with only a few hours possible
of some freezing rain mixing in for KLWB. Confidence is not high
enough in coverage and precipitation type to include anything
but rain in the TAFs. Ceilings will drop to MVFR a couple of
hours after the rain begins. For KROA, KBLF, KLWB and KBCB this
will be in the 12Z/7AM to 18Z/1PM time frame as the rain spreads
from west to east. At KLYH expect rain to begin before 18Z/1PM
but any MVFR ceilings will be after the TAF forecast period.
Bufkit forecast soundings and the SPC HREF have the rain only
reaching Danville and points east and south by the end of the
day, well after the 18Z/1PM.
Overnight Saturday and into Sunday morning, winds will be light.
Later Sunday, winds will be south and southwesterly from 5 to 10
knots, with 15 to 20 knots possible in the higher elevations of
the Southern Blue Ridge, but wind speeds decrease Sunday
evening.
Forecast confidence is average.
Extended Aviation Outlook...
A prolonged period of MVFR or IFR continued Sunday night through
Thursday with periods of rain, stratus and fog. There may be
some improvement Monday and Monday night as high pressure passes
to the north. Another cold front will provide more periods of
rain and poor flying weather for Tuesday through Thursday.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/SH/AS
SHORT TERM...DS
LONG TERM...DS
AVIATION...AMS/AS