Friday, February22, 2019 L-36.com


Marine Weather and Tides
Roanoke, VA

Version 3.4
What's New / NOTES
10/6/2018 Colors of tide XTide graphs changed to emphasize that they were upgraded. See next note. Comments welcome.
10/4/2018 I have fixed XTide and updated the harmonic files. There were some name changes so you might have to click EDIT to find the new station name.

Sunrise 6:58AMSunset 6:07PM Friday February 22, 2019 12:09 PM EST (17:09 UTC) Moonrise 9:52PMMoonset 9:09AM Illumination 89% Phase: Waning Gibbous; Moon at 18 days in cycle
NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.
Marine Forecasts
    EDIT      (on/off)   Help


7 Day Forecast for Marine Location Near Roanoke, VA
   Hourly   EDIT   Help
location: 37.28, -79.96     debug


Area Discussion for - Blacksburg, VA
      (on/off)   Help   NOTE: mouseover dotted underlined text for definition
Fxus61 krnk 221412
afdrnk
area forecast discussion
national weather service blacksburg va
912 am est Fri feb 22 2019

Synopsis
A frontal system will remain nearly stationary close to the
virginia north carolina border through Saturday. A series of
lower pressure systems aloft will track along and near the
frontal boundary bring periods of mostly light to moderate
rainfall to the region through Saturday. This will continue the
threat for flooding across the region through the weekend. A
cold front will push through the region Sunday finally bringing
an end to the rain by afternoon. Temperatures are expected to be
near normal values through the weekend.

Near term through tonight
As of 415 am est Friday...

very little change in the upper atmospheric pattern across the
u.S. Is expected through the period. Deep troughing will remain
in the western u.S. With a strong 590+dm ridge aloft just off
the florida east coast. The ridge is keeping a baroclinic
zone nearly stationary frontal boundary draped across the
region.

Meanwhile, a series of upper-level disturbances will track
northeast from the main upper low in the southwest u.S. And
along and through the baroclinic zone. To complicate matters, a
new area of canadian high pressure will move from the great
lakes toward new england allowing yet another wedge of cold air
to develop east of the appalachians, having just seen the last
one (largely responsible for our most recent snow ice storm)
depart Thursday afternoon.

With the baroclinic zone established over near the blacksburg
forecast area today through Friday and increasing isentropic
lift as the cool air wedge develops today through Saturday,
along with numerous upper-level impulses steered by the mean
southwest flow aloft across our region, look for periods of
rain today through Saturday. While most of the rain will be
light, brief periods of heavier rainfall can be expected.

Expected QPF today and tonight will be mostly in the 1 to 1.5
inch range, with the higher totals in the west where upper-level
forcing is better.

Soil conditions across much of the rnk CWA remain very saturated
thanks to repeated recent rainfall events for months on end
along with recent snow ice melt. Rainfall today and tonight will
simply aggravate the situation. Thus, the flood watch, which was
issued for the entire forecast area yesterday afternoon, will remain
in effect until Saturday night west and Sunday morning east.

Finally, there are a couple of other considerations complicated
by the development of yet another cold air wedge tonight and
early Saturday. As the cool wedge intensifies over the area
today and tonight, sufficient dry air may be entrained southward
into the northern fringe of the advancing rain shield for
temperatures to wet-bulb down toward the freezing mark late
tonight early Saturday across the southern shenandoah valley
into the greenbrier and new river valleys. Thus, a brief period
of freezing rain and or freezing drizzle is possible around
daybreak Saturday. With temperatures only expected to reach 32f
and limited to spotty locations at that, ice accumulations are
expected to only amount to a trace at best. Will mention in the
hwo ehwo, but no headlines are warranted at this time.

The other consideration related to the wedge is that the
attendant drier air advecting southwest could reduce
precipitation amounts for a while tonight Saturday morning
across northern parts of the cwa. With the wedge beginning to
erode again later Saturday into Sunday, no changes to the cwa
wide flood watch are warranted given as noted above the very
saturated soil conditions across the entire region.

With the development of a wedge once again, look for cold
temperatures to return today and Saturday. Temperatures will
hold mostly in the 30s higher elevations to 40s lower elevations
through Saturday.

Confidence in forecast parameters
temperatures - moderate to high,
precipitation probabilities - moderate to high,
winds - high.

Short term Saturday through Monday night
As of 300 am est Friday...

very active weather into the first part of next week with both a hydro
and wind threat.

The deep upper trof ejecting out of the southwestern us will amplify
the southwesterly flow aloft and moisture transport over the
appalachians and central mid atlantic region through Saturday.

Simulated water vapor imagery shows a well defined moisture plume with
teleconnections back to the pacific ocean, helping to generate
precipitable water valued of 2 to 3 standard deviations above normal.

Acting on this moisture will be prolonged strong isentropic lift as a
warm front pushes the moist air up and over a well entrenched wedge
east of the mountains. This will generate additional widespread
rainfall on top of our saturated ground, and good clustering of
ensemble precip plumes adds confidence in this very wet scenario.

Temperature profiles may also be problematic for some freezing rain
with surface readings near freezing at the typical locations in the
heart of the wedge Saturday morning, but it currently looks like we
will stay just warm enough to avoid any icing. With the ground
already saturated from recent and ongoing precipitation, expect any
ongoing flooding will be amplified and new flooding initiated before
the best forcing slides to our north by Saturday evening.

Any lull in the action will be short lived as low pressure moving into
the great lakes will push showers ahead of a cold front back into
the region form the west later Sunday night, with an outside chance
of some thunder as well but would like to see instability lapse
rates a bit more pronounced to warrant a mention in the forecast.

Low level southwesterly winds will amplify considerably ahead of the
front Saturday night with strong wind gusts developing across the
mountains of north carolina, up through the grayson highlands and
mountain empire or virginia, and into western greenbrier in west
virginia. With the waterlogged soil some uprooted trees and
associated power outages look possible. The front will cross the
area Sunday morning with the low level wind field still energized.

Expect some significant wind gusts with the actual frontal passage,
followed by strong gusty winds spreading eastward across the entire
region even into the piedmont through Sunday afternoon, along with a
greater than normal likelihood for uprooted trees and power outages
due to the waterlogged soil. Strong gusty winds will continue west
of the blue ridge as lowering inversion squeezes the flow in the
mountains. Moisture behind the front looks to be fairly limited and
this should inhibit development of upslope showers. Winds gradually
subside as high pressure builds in with quiet weather for Monday.

Long term Tuesday through Thursday
As of 345 pm est Thursday...

transient cool high pressure will move out to sea Tuesday night. A
northern stream cold front will join forces with a southern stream
disturbance late Tuesday night Wednesday morning to bring a chance for
rain back into the area. At this time, the two do not phase until both
systems move off the mid atlantic coast Wednesday evening. Dry high
pressure will follow with no rain expected until the weekend.

Near normal temperatures are expected for next week.

Aviation 14z Friday through Tuesday
As of 645 am est Friday...

poor aviation conditions expected through the TAF valid period.

Most conditions early this morning are MVFR, but are expected to
deteriorate quickly to ifr-lifr by mid to late morning and
remain mostly ifr-lifr through the remainder of the TAF valid
period in light rain and fog, transitioning to light rain,
drizzle, and fog overnight into early Saturday. Ceilings will
mostly fall into the 005-015 range while visibilities generally
hold in the 2-4sm range through 22z, then mostly in the 1 2-2sm
range after 22z. This as the result of a stationary front
draped across the region which will remain in the area through
Saturday while high pressure to our northeast helps to develop
another wedge through the day today into Saturday, and a series
of upper-level disturbances move northeast from deep low
pressure in the south central u.S.

Winds will generally trend toward the east and northeast as weak
low pressure remains to our southeast and high pressure
strengthens to our northeast. Speeds are expected to be mostly
5-6kts or less through the TAF valid period. As southeast flow
develops toward the kblf area, speeds may increase in that
region more toward 10kts with low end gusts.

Confidence in forecast parameters
ceilings - moderate to high,
visibilities - moderate to high,
winds - moderate to high.

Extended aviation discussion...

cold front is expected to sweep east through the terminal
forecast area on Sunday, gradually diminishing ending the threat
for precipitation with subsequent return toVFR conditions east
of the blue ridge by during the afternoon.

However, colder upsloping winds from the west or northwest
following the frontal passage will likely maintain the threat
for sub-vfr weather west of the blue ridge through Sunday
night, but dry air will allowVFR conditions to return to all
areas Monday, which should continue into Tuesday before the next
frontal system arrives in the wed-thu time frame.

Winds are expected to become quite strong and gusty behind the
front Sunday into Monday, especially over the mountains, until
high pressure can sufficiently build into the region later
Monday into Tuesday, thereby allowing winds to gradually relax.

Hydrology
As of 430 am est Friday...

a quasi-stationary frontal boundary will remain over or near the
rnk CWA during the next several days as a series of weather
disturbances lift northeast along the boundary. Each system will
bring a period of widespread mostly light to moderate rain,
possibly briefly heavy at times, especially in the south and
west. Rainfall totals over the next several days are expected
to be in the 1 to 3 inch range in many areas, with locally
higher amounts quite possible. Runoff from rain falling on a
totally saturated ground from a very wet fall and winter season,
combined with recent snow ice melt, will increase the threat of
general areal flooding in low-lying, poor drainage, and normally
flood prone areas as well as along creeks, streams, and even
some of the main rivers with time.

Ensemble river forecasts reflect minor to potentially moderate
flooding of most major waterways and associated tributaries.

Please remain abreast of possible flood and river flood warnings
that me be issued through the weekend.

Rnk watches warnings advisories
Va... Flood watch through late Saturday night for vaz007-009>020.

Flood watch through Sunday morning for vaz022>024-032>035-
043>047-058-059.

Nc... Flood watch through late Saturday night for ncz001-002-018.

Flood watch through Sunday morning for ncz003>006-019-020.

Wv... Flood watch through late Saturday night for wvz042>044-507-508.

Synopsis... Rab
near term... Rab
short term... mbs
long term... mbs rcs
aviation... Rab
hydrology... mbs rab wert


Weather Reporting Stations
   EDIT       (on/off)   Help   NOTE: Click on distance to see the station location on a map

Airport Reports
    EDIT      (on/off)   Help   Click EDIT to display multiple airports
AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Roanoke, Roanoke Regional Airport, VA3 mi16 minN 010.00 miLight Rain46°F42°F86%1028.8 hPa
Virginia Tech Airport, VA24 mi35 minE 510.00 miLight Drizzle44°F44°F100%1028.1 hPa

Wind History from ROA (wind in knots)
1
PM
2
PM
3
PM
4
PM
5
PM
6
PM
7
PM
8
PM
9
PM
10
PM
11
PM
12
AM
1
AM
2
AM
3
AM
4
AM
5
AM
6
AM
7
AM
8
AM
9
AM
10
AM
11
AM
12
PM
Last 24hrW8NW11W5SW7W9
G17
SW8NW7NW5NW6CalmN3N4NE3N8NE5NE5CalmCalmN4NE5NE5N6CalmCalm
1 day agoE3CalmCalmCalmSW4S4CalmSE8CalmCalmCalmCalmSE3CalmN3NE5N7N3NE4NW6NW7W11NW4W6
2 days ago334SE5SE7SE6SE3SE6E6S7S11CalmSE6E5E4SE8SE11SE9SE6SE8SE8S6SE6Calm

Tide / Current Tables for
   EDIT   RT Ports Option   Weekend mode (on/off)   (on/off)   Help
Tide / Current Tables for
   EDIT      (on/off)   Help
Weather Map and Satellite Images
       (on/off)   HelpWeather Map
wmap_A
GOES Local Image of    EDIT
NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Blacksburg, VA (12,3,4,5)
      (on/off)   Help

Ground Weather Radar Station Blacksburg, VA
   (on/off)   Help
weather_mapweather_map weather_map

Ad by Google

Disclaimer:
The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with L-36.com. I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerious of sources and is presented automatically. It is not checked for accuracy either by anyone at L-36.com or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.