Storm Summary

NATIONAL WEATHER SUMMARY

DECEMBER 2016

1-10: A trough of low pressure generated active weather across the Four Corners and the
southern Plains 0 Friday, while rain and mountains snow affected the Northwest. A trough
of low pressure m ved east southeastward over northwest Mexico. This system drew
moisture from th Gulf of Mexico, which lead to the development of rain and thunderstorms
across the southe 11 Plains and the western Gulf Coast. Coastal flood advisories were issued
in southeast Texa and southwest Louisiana. Just to the west, high pressure generated
strong offshore w nds across central and southern California. High wind warnings and wind
advisories were i ued for a large span of the state. Tustin, Calif., recorded wind gusts of 65
mph. Corona, Cal f., recorded wind gusts of 61 mph. Meanwhile, a Pacific frontal system
approached the N rthwest. As a result, light to moderate rain and high elevation snow
developed from ashlnqton to Oregon. Back east, a mixture of rain and snow continued to
fall in portions of he upper Midwest, the northern Mid-Atlantic and New England.

A low pressure s tern generated strong thunderstorms across the Deep South on Monday,
while a separate vstern brought wintry weather to the northern Plains. An area of low
pressure strengt ened as it moved east northeastward across the Gulf Coast. This system
ushered heavy ra 11 and strong to severe thunderstorms over many states stretching from
the southern Plai 5 to the Southeast. To the north, a weak disturbance produced a light
mixture of rain a d snow from the upper Midwest to New England. Meanwhile, a stronger
area of low press re generated moderate to heavy precipitation and strong winds from the
upper Intermoun aln West to the upper Mississippi Valley. A frigid air mass also surged
across the North est and the upper Intermountain West. Stanley, Idaho, recorded a
morning low of - degrees. Baker, Ore., recorded a morning low of 3 degrees. Additionally,
an onshore flow rom the Pacific generated light to moderate rain and mountain snow from
northwest Orego . to western Washington.

A mixture of rain freezing rain and snow impacted portions of the Northwest on Friday,
while lake effect now continued across the upper Midwest and the Northeast. A Pacific
frontal system b gan to move onshore over the Pacific Northwest and northern California. II
plume of moistu e interacted with this system, which lead to the development of moderate
rain from north st California to western Washington. Further inland, a mixture of freezing
rain and snow a ected the higher elevations of the Olympics, the Cascades, the northern
Great Basin and he northern Rockies. Most areas across the Southwest experienced dry
conditions on Fri ay. Los Angeles, Calif., recorded a midday high of 63 degrees. Meanwhile"
a frigid air mass continued to stream across the Great Lakes. This interaction kept lake
effect snow in t : picture for parts of the upper Midwest and the Northeast. Lake effect
snow warnings ere issued in northeast Ohio, northwest Pennsylvania and portions of
western New Yo k. Perrysburg, N.Y., reported a midday total of 19.1 inches of snow.
Ironwood, Mich. reported a midday total of 15.8 inches of snow. Cold and dry weather
prevailed over t e northern and central Plains. Hettinger, N.D., recorded a morning low of··
23 degrees with a wind chill factor of -37 degrees. Additionally, a stalled out frontal
boundary gener ted light to moderate rain along the southern edge of the Florida Peninsula.

11-17: An area of low pressure transitioned across the Northeast on Monday, while a blast
of cold air surge over the upper Intermountain West, the northern Plains and the upper
Midwest. A broa area of low pressure shifted east northeastward over the eastern Great

Lakes, southeast anada and the Northeast. Moderate to heavy snow and gusty winds
impacted the upp r Midwest, Upstate New York and northern New England. Another cold
frontal boundary tretched southwestward over the upper Mississippi Valley, the northern
Plains and the Int rmountain West. Scattered snow showers formed near this frontal
boundary over th northern tier of the country. Arctic air also surged across the region on
Tuesday. Wind ch II advisories were issued for northern Montana. Glasgow, Mont., recorded
a morning low of 12 degrees with a wind chill factor of -27 degrees. Just to the west, an
onshore flow bro ~Jht light to moderate rain and mountain snow to Washington and
northwest Orego .

Rain and snow im iacted the Northwest on Wednesday, while lake effect snow affected the
upper Midwest an 'I the Northeast. A low pressure system approached the West Coast. This
system interacte with a plume of moisture, which lead to the development of heavy rain in
northern Californi and western Oregon. Meanwhile, a frigid air mass surged over the
northern Plains, t e Midwest and parts of the Northeast. Wind chill advisories were issued
from The Dakota to the central Appalachians. Cut Bank, Mont., recorded a morning low of .'
18 degrees with wind chill factor of -36 degrees. Aurora, III., recorded a morning low of -
11 degrees with wind chill factor of -28 degrees.

Weather Undergr und midday recap for Friday, December 16, 2016

eloped from the Intermountain West to the Great Lakes on Friday, while
the Southwest. An area of low pressure shifted over the Great Basin and
the Intermountai West. This system interacted with a moist air mass and generated a
mixture of rain a d snow over northern California, the Great Basin and the Intermountain
West. Heavy sno impacted western facing mountain slopes, especially in the Sierra
Nevada, the Was tch and the Rockies. Meanwhile, widespread snow impacted the northern
Plains and the up ler Midwest. Additionally, a blast of arctic air affected the northern tier of
the country. Mou t Washington, N.H., recorded a morning low of -34 degrees with a wind
chill factor of -87 degrees. Dickinson, N.D., recorded a morning low of -4 degrees with a
wind chill factor f -25 degrees.

18-24: A cold fr ntal boundary will clear most of the East Coast on Monday, while a
separate system 'rings impacts to the Northwest. A cold frontal boundary will extend
southwestward 0 er the western Atlantic, the Florida Peninsula and the Gulf of Mexico. Rain
and embedded t understorms will develop along and near this frontal boundary across
portions of the s uthern Mid-Atlantic, the Southeast and the Gulf Coast. Freezing rain will be
possible in parts f eastern North Carolina. Northwest of the frontal boundary, arctic air will
surge east south astward over the Midwest, the Mid-Atlantic and the Northeast. Most states
across the easte n half of the country will experience below normal temperatures on
Monday. Meanw ile, a couple waves of low pressure will transition east southeastward over
south central Ca ada and the upper Great Lakes. As a result, light to moderate snow
showers will dev lop in parts of northern North Dakota, northern Minnesota, northern
Michigan and we tern New York. Further to the west, a cold frontal boundary is expected to
generate moder e to heavy rain and mountain snow in the Pacific Northwest and the upper
Intermountain st. Portions of the interior Pacific Northwest may experience freezing rain
on Monday. Mos of the Great Basin and the Southwest will stay dry.

An area of low pr ssure transitioned across the Northeast on Monday, while a blast of cold air

surged over the per Intermountain West, the northern Plains and the upper Midwest. A broad

area of low press re shifted east northeastward over the eastern Great Lakes, southeast
Canada and the ortheast. Moderate to heavy snow and gusty winds impacted the upper
Midwest, Upstate New York and northem New England. Another cold frontal boundary stretched

southwestward ov r the upper Mississippi Valley, the northern Plains and the Intermountain
West. Scattered SDW showers formed near this frontal boundary over the northern tier of the
country. Arctic air Iso surged across the region on Tuesday. Wind chill advisories were issued
for northern Mon na. Glasgow, Mont., recorded a morning low of -12 degrees with a wind chill
factor of -27 deqr is. Just to the west, an onshore flow brought light to moderate rain and
mountain snow to Vashington and northwest Oregon.

25-31: The Plain experienced dry weather on the 29^th. A mix of rain and snow is fell across
the lower Great L kes region. Breezy, colder air is overspreading the remainder of the
Midwest, accomp nied by a few snow showers. In the South, showers stretching from the
Mid-Atlantic regi I to the central Gulf Coast are associated with a developing storm system.
The rain is furthe helping the Southeast recover from a serious autumn drought.