winter storm tomorrow-tomorrow night · higher in an extended period of poor travel conditions...
TRANSCRIPT
Philadelphia/Mount Holly
Weather Forecast Office Presentation Created 2/19/2019
4:12 PM@NWS_MountHolly NWSMountHolly
Winter Storm Tomorrow-Tomorrow Night
What Has Changed?
Initial Briefing
Decision Support Briefing #1
As of 4:30 PM
Tuesday, February 19, 2019
Philadelphia/Mount Holly
Weather Forecast Office Presentation Created 2/19/2019
4:12 PM@NWS_MountHolly NWSMountHolly
Main Points
Hazard Impacts Location Timing
Snow
Snow will create hazardous
travel conditions.
Roadways will be snow
covered. Travel conditions
for most of the day
Wednesday will be
impacted, and there is
particular concern
regarding the evening
commute.
NJ, east-central and
southeast PA, DE,
northeast MD.
Snow will gradually
overspread these areas
from southwest to
northeast tomorrow
morning, from around
6AM to 12PM, with the
most intense snow in the
late morning and early
afternoon.
Sleet and
Freezing
Rain
A period of sleet and
freezing rain following the
initial period of snow will
exacerbate already
hazardous travel
conditions, with up to a
tenth of an inch of ice
accumulation.
Eastern and
southeastern PA,
northern and
western NJ, far
northeast MD, far
northern DE.
Snow will transition to an
extended period of sleet
and freezing rain from
mid-afternoon through
the evening. Elsewhere,
snow should transition to
rain with only a brief mix
expected.
Philadelphia/Mount Holly
Weather Forecast Office Presentation Created 2/19/2019
4:12 PM@NWS_MountHolly NWSMountHolly
Wintry Mix: E PA, N and W NJ, N DE, NE MD
Snow: NJ, E PA, DE, NE MD
None Limited Elevated Significant Extreme
Summary of Greatest Impacts
None Limited Elevated Significant Extreme
Philadelphia/Mount Holly
Weather Forecast Office Presentation Created 2/19/2019
4:12 PM@NWS_MountHolly NWSMountHolly
Expected Snowfall Accumulations
Uncertainty in Snowfall
Forecast:
As with other storms this
season, considerable
uncertainty exists in the
snowfall forecast owing to
critical timings of transitions
between snow, ice, and rain.
While confidence in exact
snowfall totals is medium at
best, confidence is higher on
a period of significant and
widespread travel impacts,
especially from mid-morning
through the evening.
Philadelphia/Mount Holly
Weather Forecast Office Presentation Created 2/19/2019
4:12 PM@NWS_MountHolly NWSMountHolly
Probabilistic Snowfall Forecast
Low End Potential9 in 10 (90%) Chance of Higher Snowfall
Than Depicted Below
High End Potential1 in 10 (10%) Chance of Higher Snowfall Than
Depicted Below
Philadelphia/Mount Holly
Weather Forecast Office Presentation Created 2/19/2019
4:12 PM@NWS_MountHolly NWSMountHolly
Expected Ice Accumulations
Ice accumulation notes:
Icing of a few hundredths to
a tenth of an inch is
generally insufficient to
produce tree damage or
power outages, but any
amount of ice is capable of
creating very hazardous
road conditions.
Philadelphia/Mount Holly
Weather Forecast Office Presentation Created 2/19/2019
4:12 PM@NWS_MountHolly NWSMountHolly
Precipitation Onset Time
Onset Time Notes:
This map represents our
best estimate for when
snow will begin tomorrow.
Owing to cold temperatures
tonight, snow should begin
accumulating on all
untreated surfaces soon
after it begins falling.
Philadelphia/Mount Holly
Weather Forecast Office Presentation Created 2/19/2019
4:12 PM@NWS_MountHolly NWSMountHolly
A winter storm will impact the area from early tomorrow morning through tomorrow
night. A variety of precipitation types are expected. Travel impacts are likely for most
of the day Wednesday, except in central and northern NJ and east-central PA where
most of the morning should remain dry before snow begins. For all areas, the
evening commute is the period of greatest concern, but morning commute impacts
are possible in northeast MD, DE, southern NJ, and far southeast PA
All areas will likely see precipitation begin as snow. A gradual transition from snow to
a mix of sleet and freezing rain, then rain, will occur tomorrow afternoon and evening.
Rain will continue for most of the night, potentially ending near daybreak Thursday.
Over far northern NJ and the Poconos, precipitation may never transition to plain
rain, instead staying as a mix of sleet and freezing rain after the initial period of snow.
Considerable uncertainty exists in how much snow will fall. However, confidence is
higher in an extended period of poor travel conditions during most of the daytime
hours tomorrow, with particular concern for the afternoon and evening.
Up to a tenth of an inch of ice is expected in eastern PA and northern NJ, which will
lead to hazardous travel conditions into Wednesday night. Over southern NJ and
Delmarva, only a brief period of icing is expected before a transition to rain.
Localized minor coastal flooding is possible during the Wednesday morning high tide
cycle, but this is not expected to be a widespread or significant concern. Strong winds
are also not expected to be a concern.
Event Summary
Philadelphia/Mount Holly
Weather Forecast Office Presentation Created 2/19/2019
4:12 PM@NWS_MountHolly NWSMountHolly
Web:
www.weather.gov/phi
Phone (public):
(609) 261-6600
Facebook:
NWSMountHolly
Twitter:
@NWS_MountHolly
Contact and Next Briefing Information
Briefing Webpage:
www.weather.gov/media/phi/current_briefing.pdf
Next Briefing By 6:00 AM Wednesday,
February 20, 2019
Disclaimer: The information contained in this briefing is time-
sensitive; do not use after the next briefing package is issued.