NWS Winter Weather Discussion
County Warning Area [CWA]: LWX
Regional NWS Weather Office: Baltimore/Washington DC, Virginia

Likely Snow or Ice Ranges and Start Times Snow or Ice Storm Fall Probabilities

Likely Snow or Ice Ranges and Start Most Likely Snow or Ice Storm Total Expect at Least this much Snow or Ice
Potential for this much Snow or Ice Likely Start Time of Winter Precipitation
Most Likely Ice Glaze
Most Likely Snow Fall Totals 2000Z Outlook
Images courtesy of the NWS Baltimore,MD-Washington,DC Office
 Forecast Disussion
Forecast Discussion

FXUS61 KLWX 211759

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
159 PM EDT Fri Jul 21 2017

.SYNOPSIS...Weak upper level disturbances will be possible
tonight through Sunday. An upper level trough of low pressure
will move over the northeastern US early in the new week.



Showers and thunderstorms moving across the Appalachians will
likely hold together as they move across the southern half of
the fcst area. Thermodynamic profiles are very warm aloft
(-3C @500 mb) and no svr warnings have been issued by offices
to the west. T-storms will likely dissipate during the early
evening. Otherwise, another very warm and muggy night similar to
last night but with more cloud cover.


models continue to show an MCS forming over southern Wisconsin
late tonight and moving across Chicago and eastern OH and wrn PA
by Sat morning. While this complex is expected to weaken toward
daybreak, redevelopment is expected during the afternoon across
the local area. 0-6km shear increases somewhat supporting
organized convection. CAPE is also on the increase given hotter
temperatures and plenty of moisture (850 mb dewpoints of 15C).
Some severe wx is possible, but ensemble guidance shows a large
spread in CAPE values with some members showing only weak CAPE.

Sunday appears to be shaping up a potentially more significant
severe convective day. Models progged a stronger upper level
disturbance with significant height falls for summertime
standards. Shear is also on the increase and many ensemble
members show moderate CAPE and some even high CAPE values over
3500 J/kg. Expect clusters of storms to move across the area
some with damaging winds.



A cold front will approach the region Monday before pushing across
the region Monday night. Showers and thunderstorms will develop
along and ahead of this front. Highs will reach the 90s again.

The front could stall just to our south Tuesday, allowing for a
couple of showers or a thunderstorm to develop.

High pressure will build in from the west and northwest Tuesday
night through Thursday. Temperatures will be nearly 10 degrees
cooler than previous days with a comfortable relative humidity.

The next cold front will arrive and push across the region Thursday
night and Friday. Another active pattern of showers and
thunderstorms during the period and could linger into the weekend if
the front stalls across portions of the region.


tonight. A t-storm is possible at KCHO. Sct-nmrs t-storms more
likely Sat and especially Sun.

Mvfr to ifr conditions possible with showers and thunderstorms
Monday and Monday night. Vfr conditions expected Tuesday. A shower
cant be ruled out. Winds northwest becoming southwest 5 to 10 knots
Monday and Monday night. Winds north 10 knots Tuesday, becoming
northeast 5 to 10 knots Tuesday night.


.MARINE...Sct-nmrs t-storms Sat and Sun may require SMWs.

No marine hazards expected Monday through Tuesday night. Winds
southwest 5 to 10 knots Monday and Monday night. Winds becoming
northwest 10 knots Tuesday, then northeast 5 to 10 knots Tuesday



Late July is climatologically the warmest time of the year,
just like six months from now is the coldest time. How has the
heat of 2017 compared with heat waves (up to now) in other
years? I chose "consecutive days that reached 90 and above" as
the criteria.

At DCA there have been two times this summer with stretches of
six consecutive days - beginning June 29 and again July 10. In
terms of ranking (going back to 1871) these are #49 and 50.
Currently DCA has exceeded 90 on four consecutive days.

July 16 was 89, otherwise DCA would have exceeded 90 on eleven
days in a row.

For Baltimore there were also six consecutive days beginning
June 29, which puts it in 37th place. Currently BWI has
exceeded 90 on four consecutive days.

July 16 was 89, otherwise BWI would have exceeded 90 on eleven
days in a row.

The all-time record for June-Aug: for Baltimore 25 consecutive
days beginning 7/12/1995. For DC there have been two periods of
21 consecutive days - beginning 7/29/1988 and 7/25/1980.


DC...Heat Advisory until 8 PM EDT this evening for DCZ001.
MD...Heat Advisory until 8 PM EDT this evening for MDZ011-013-014-
VA...Heat Advisory until 8 PM EDT this evening for VAZ037>039-



Record Report from: NOAA-NWS
Script developed by: El Dorado Weather & modified by: SE Lincoln Weather