Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Blacksburg Virginia
911 am EDT sun Mar 29 2015
high pressure over the middle Atlantic region will move southeast
today and off the Carolina coast tonight. A cold front over the
northern plains will move east and cross through the region
Monday morning. A second front and clipper system will pass across
the area on Tuesday...followed by high pressure for the middle of
Near term /through tonight/...
as of 905 am EDT Sunday...
It is a very cold morning across our region. Rer out with record
lows that were broken or tied this morning. High pressure over
the middle Atlantic region will move southeast today and then off
the Carolina coast tonight. Made a few minor adjustments to
temperatures this morning into this afternoon. In general...leaned
temperatures towards the lav values for late morning. More changes
later today. Enjoy your Sunday.
As of 400 am EDT Sunday...
This morning high pressure was centered over West Virginia. Winds
have diminished slightly since midnight but highest elevations
still had gusts 15 to 20 miles per hour. Surface dew points were in the
single digits and teens. Local profiler continued to show
precipitable water values below 0.10 inch. Very dry air mass and
full sunshine today will lead to a large temperature rise. In
addition...850 mb temperatures will start to moderate this
afternoon as low level winds come around to the south-southwest.
Stayed closer to warmer guidance for maximum temperatures.
Cloud cover spread across the area this evening in advance of an
approaching cold front. Models have trended slower with the
arrival of precipitation in the region. Have adjusted onset time
of precipitation until 03z/11pm and increased probability of
precipitation toward 12z/8am. Models showed precipitable water
rising above 0.50 inch. Have kept quantitative precipitation forecast with this feature under one
quarter of and inch.
Winds pick up ahead of the front but BUFKIT showed strongest
winds ahead of the front just above the surface and remaining
above the inversion.
Short term /Monday through Wednesday night/...
as of 345 am EDT Sunday...
Expect to start Monday with a cold front passing across the area...
triggering a broken line of rain showers making its way east across
the Piedmont. Shower activity will diminish quickly behind the front
as winds shift west northwesterly/downslope as high pressure builds
in from the Central Plains. This area of high pressure is Pacific in
origin...lacking the colder characteristics of the Canadian
airmasses we have all become familiar with over the past few months.
As such...and taking into account the decreasing cloud cover heading
into the afternoon...expect high temperatures to range from the
low/middle 50s across southeast West Virginia...to the middle 60s across
Winds will shift increasingly southwesterly during late Monday
evening as high pressure advances over the southeast states...and an
area of low pressure swings across the lower Great Lakes. The
southwesterly flow will allow Tuesday afternoon highs to range from
the low/middle 60s west...to the upper 60s east...under mostly sunny
skies. During Tuesday evening...the low pressure system will pass
across lower New England...dragging a cold front southward across
the middle Atlantic. May see a few rain showers across the western
ridges...however this system will have very little moisture to work
with...and shower activity should only last a few hours.
Dry high pressure will pass across the Great Lakes in the wake of
the cold front...pushing over New England and wedging against the
eastern face of the Appalachians. Winds will shift increasingly
southerly Wednesday night as high pressure continues to push
east...and may see patchy drizzle/fog develop before dawn Thursday
along the Blue Ridge as Atlantic moisture pushes upslope.
Long term /Thursday through Saturday/...
as of 200 PM EDT Saturday...
High pressure will continue to depart eastward off the middle Atlantic
coast Thursday morning...with a surge of moisture pushing northward along
the Blue Ridge per southeast flow. With modest instability present...
looking at a chance of rain from along and west of the Blue
Ridge...with possibly eastward extent into the southern County Warning Area per flow off
the Atlantic early on in the day...before veering winds turn more
SW. Highs Thursday will be mild but could be cooler per more clouds
and higher rain chances. If the high slows down or shifts further
north...thus allowing longer easterly fetch...then temperatures could be 5-
10 degrees cooler out east....but still near normal.
As we head into Thursday night-Friday the forecast varies...though
the new 12z European model (ecmwf) shows similar setup that the 12z GFS does with
front orientation setting up in an east-west fashion with parallel
flow aloft. This is going to keep the area in a unsettled pattern
with next main low across the Central Plains Friday arriving over
the Ohio Valley/central Appalachians Friday afternoon/evening. The
difference in the models is that the European model (ecmwf) shows a stronger low
moving more north over the Great Lakes...while the GFS has weaker
low moving across WV into northern Virginia. The European model (ecmwf) solution as such has
less quantitative precipitation forecast than the GFS. Nonetheless threat of rain showers will
continue into Saturday. The airmass behind the front will be cold
though the ecwmf is much more amplified and colder than the GFS.
Could see upslope snow showers in the mountains Saturday night.
Aviation /13z Sunday through Thursday/...
as of 720 am EDT Sunday...
High pressure over the Middle Atlantic States will move southeast
today and off the Carolina coast tonight. A cold front will cross
through the region from the west Monday morning.
Surface winds will be light and variable this morning then
increase from the south-southwest this afternoon and evening.
Higher elevations may have gusts up to 30 knots just ahead of the
front. Winds will shift to the west then northwest behind the
High clouds will spread across the area ahead of the
front...mainly after 00z/8pm. High confidence in VFR conditions
during the taf period. Medium confidence that ceilings will drop
to MVFR in the mountains as the rain arrives.
Extended aviation forecast...
A period of MVFR ceilings along with a band of showers is possible in
the mountains late Sunday night and Monday morning.
There is also potential for strong gusty winds behind the front
Monday and again Tuesday as another clipper slides across from the
Weak high pressure should maintain mainly VFR conditions Tuesday
into Wednesday with only lingering mountain upslope driven MVFR
ceilings on Tuesday.
Moisture will again increase ahead of a stronger cold front
Thursday with a return to sub-VFR conditions possible.
as of 455 am EDT Friday...
Record lows for March 29:
Roanoke......19 in 1982
Blacksburg...17 in 2001
Lynchburg....23 in 1923 and 1982
Danville.....23 in 1966
Bluefield....19 in 1966 and 1982
Lewisburg....18 in 1983