|
WARNING & ADVISORY CRITERIA |
|
WFO Chicago/Romeoville, IL
(LOT) |
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Last Updated - 10/06/08 |
|
Warning Type |
Warning Criteria |
Advisory Type |
Advisory Criteria |
|
Blizzard
|
Sustained wind/frequent gust
> 35 mph & visibility
<1/4 mile in snow/blowing
snow for 3 hours or more
|
Winter Weather (snow and
blowing snow) |
wind 25-34 mph and
visibility occasionally
< 1/4 mile from
falling and blowing snow |
|
Winter Weather (blowing
snow) |
wind 25-34 mph and
visibility occasionally
< 1/4 mile from
blowing snow |
|
Winter Storm (snow) |
< 6" in < 12
hours / > 8" in <
24 hours |
Winter Weather (snow) |
usually 3: to 5:, 2: to 4:
optional |
|
Ice Storm |
Ice accumulation > 1/4" |
Freezing Rain |
ice accumulations < 1/4" |
|
Lake Effect Snow |
< 6" in < 12
hours / > 8" in <
24 hours |
Lake Effect Snow |
usually 3: to 5:, 2: to 4:
optional |
|
Winter Storm (sleet) |
Sleet accumulation >
1/2" |
Winter Weather (sleet) |
Sleet accumulation < 1/2" |
|
Wind Chill |
WC < -30 degrees F &
winds > 5 mph |
Wind Chill |
WC < -20 degrees F &
winds > 5 mph |
| |
Dense Fog |
widespread or localized
visibility < 1/4 mile |
|
Excessive Heat
|
Chicago/Cook County:
1) 3 consecutive days peak
Heat Index 100-105 degrees
F.
2) 2 consecutive days with
peak Heat Index 105-110
degrees F.
3) 1 day with peak Heat
Index 110 degrees F or
greater |
Heat
|
Chicago/Cook County
None |
|
Elsewhere:
Max. Heat Index > 105
degrees F and Min. Heat
Index > 75 degree F
for 48 hours |
Elsewhere:
Max. Heat Index > 100
degrees F and/or Max. temp
> 95 degrees F.
(Consider upgrading to
warning if conditions
persist 4 days or more) |
|
Freeze |
widespread temps < 32
degrees F during growing
season |
Frost |
widespread frost in growing
season |
|
|
Freezing Fog |
widespread ice from freezing
fog |
|
High Wind |
sustained winds > 40
mph gusts > 58 mph |
Wind |
sustained winds > 30
mpg gusts > 45 mph |
|
Red Flag |
Sustained 20 foot winds 20
mph or greater afternoon RH
< 25%, 10 hour fuel moister
< 8 % |
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