DATASTREME DAILY SUMMARY
Thursday, 23 November 2000
Happy Thanksgiving Day!
This week is Thanksgiving Week recess. This DataStreme Daily Summary
contains the Historical Weather Events for this date. Current
weather data are available on the homepage as usual. The Week
10 Activity files will remain available through this week. If
you are looking for an alternative description of daily weather,
you could try
http://www.usatoday.com/weather/ wlead.htm
CONCEPT FOR THE DAY - FORECASTING THE WEATHER
NOTE: This Concept for the Day is a repeat
of that which appeared in the previous week's Thursday Weather
Summary.
Most of us would like to know what the weather will be for many
reasons. We would like to know what to wear to an outdoor sporting
event, or we may need to take appropriate action to save ourselves
from potential severe weather. For centuries, humans developed
various means for forecasting, including the rich weather lore
that may or may not involve sound physical rationale. A major
focus in modern meteorology entails the development of methodologies
to make accurate forecasts of future weather events using proven
scientific methods.
So how can we make a reasonable scientific weather forecast? We
will consider just the next several days, since forecasts for
more than several days are considered to be outlooks of general
trends. Obviously, the easiest method would be to consult the
local forecast prepared by the National Weather Service. Their
forecasts are based upon an array of various "numerical
weather prediction" models that are run on computers
using weather data from surface weather observation stations,
radiosondes and weather satellites.
If we were not able to receive a forecast, we could make a reasonable
forecast. One method would be by "persistence",
which assumes that the weather would remain the same or persist
throughout the forecast period. In other words, if you step out
and observe sunny skies and mild temperatures, you would make
a forecast that these conditions would continue for the next hour
or two. Often times this type of forecast would be reasonable
for a short time, particularly if a large high pressure cell is
nearby. The accuracy of this method decays rapidly with time.
Another forecast method would involve "climatology",
where the forecast is based upon some long term climatological
average. In other words, you would forecast tomorrow's high temperature
as being the same as the "normal" high temperature for
tomorrow. This type of forecast may fail if an extremely cold
or warm air mass moves into the your region.
We could also use single station forecasts, by watching the sequence
of weather that evolves in combination with the looking at the
current weather map. We have discussed how you can locate where
the low (or high) pressure cell would be relative to you by facing
downwind. Looking at the current weather map helps pinpoint the
positions. We can also refine our forecast skills by looking for
changes in the wind direction, cloud types, air pressure and air
temperature over several hours, especially if a mid-latitude cyclone
were approaching. Using your WeatherCycler or the description
on pages 184-185 of Part A of the DataStreme Study Guide,
you determine whether you will be on the warm side or cold side
of the storm. In addition, you can look at a sequence of surface
weather maps and attempt to extrapolate the movement of the weather
systems that would cross your area.
For a description of how to read and interpret the Forecast charts
on the DataStreme Homepage, you can read the optional Thursday
Supplemental Information.
QUESTIONS:
To be submitted on the lines for Thursday on the Study Guide,
Part B, Applications', Week 10 Chapter Progress Response Form,
under section B. Daily Summary.
- An often satisfactory forecast for the next hour or so can
be made using [(persistence) (climatology)].
- The weather forecast for tomorrow prepared by the National
Weather Service is based on [(persistence) (climatology)
(numerical weather prediction models)].
HISTORICAL WEATHER EVENTS - 23 November
From the files of the Aviation Weather Center, Kansas City,
MO and Intellicast
- ...1909...Rattlesnake Creek was deluged with 7.17 inches of
rain in 24 hours to establish a record for the state of Idaho.
(The Weather Channel)
- ...1943...Northern New Hampshire was in the grips of a record
snowstorm which left a total of 55 inches at Berlin, 56 inches
at Randolph and many other locations over 40 inches. The 56 inch
total at Randolph in Coos County established a 24 hour snowfall
record for the state. In Maine, Middle Dam received a record 35
inches of snow in 24 hours. (David Ludlum)
- ...1974...Bismarck, ND was in the middle of a 5 day snowstorm
during which 28.3 inches fell, the greatest on record. (Intellicast)
- ...1983...A 24 hour snowfall record for Duluth, MN was broken
with 16.9 inches. 19.7 inches fell during the entire storm, also
a record.
- ...1987...Rain and gale force winds prevailed along the Northern
Pacific coast. Quillayute, WA received 1.57 inches of rain in
24 hours, including nine tenths of an inch in six hours. Heavy
snow fell over northern Oregon and the Cascade Mountains of Washington
State. Temperatures began to moderate in the eastern U.S. following
a bitterly cold weekend. (The National Weather Summary)
- ...1988...Low pressure crossing the Great Basin brought wintry
weather to parts of the western U.S. Up to a foot of snow blanketed
Yellowstone Park, and winds gusted to 70 mph at Casper, WY, and
reached 95 mph near Reno, NV. Up to seven inches of rain was reported
in the Grass Valley and Nevada City area of California. Paradise,
CA was soaked with 5.37 inches of rain in 24 hours. (The National
Weather Summary) (Storm Data)
- ...1989...Low pressure tracking across the Carolinas brought
heavy rain to parts of the Southern Atlantic Coast Region for
Thanksgiving Day, and blanketed the Middle Atlantic Coast States
and southern New England with heavy snow. The storm produced up
to nine inches of snow over Long Island NY, 14 inches over Cape
Cod, MA, at South Yarmouth, 12 inches at Chatham and 4 inches
at Boston. Totals of 4.7 inches at New York City and 6.0 inches
at Newark, NJ were records for Thanksgiving Day, the 8.0 inch
total at Providence, RI was a record for any given day in November,
and the 6.5 inch total at Strasburg, CT was a record for the month
of November as a whole. (The National Weather Summary) (Storm
Data)
- ...1991...La Crosse, WI set a new record for 24 hour snow
with 13 inches. This storm brought the monthly total to 28.2 inches,
also a record. (Intellicast)
- ...1992...Early morning severe thunderstorms spawned two F3
tornadoes in North Carolina resulting in 2 deaths and 59 injuries.
This was the last day of the three day outbreak in which 93 tornadoes
touched down claiming 25 lives. Alta, UT was buried under 45 inches
of snow in 24 hours to set an all-time 24 hour record for that
location. (Intellicast)
Return to DataStreme Homepage
URL Address: datastreme/learn/r_sum.html
Prepared by Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2000, The American Meteorological Society.