RSS FeedsIssued by NWS Chicago, IL
Versions: 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
000 FXUS63 KLOT 100513 AFDLOT AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 1113 PM CST TUE FEB 9 2010 .DISCUSSION... 306 PM CST SHORT TERM...TONIGHT AND WEDNESDAY... HAVE DECIDED TO DROP BLIZZARD WATCH ACROSS SOUTHEASTERN CWA DUE TO CONCERNS ABOUT MEETING STRICT CRITERIA. OTHER THAN MINOR TWEAKS TO SNOW AMOUNTS HAVE MAINTAINED SHORT TERM FORECAST PRETTY MUCH AS IS THROUGH WEDNESDAY. AFTERNOON SATELLITE IMAGERY SHOWS STOUT UPPER LOW NEAR STL...WHICH WILL CONTINUE TO MOVE EAST/SOUTHEAST ACROSS OHIO RIVER VALLEY TONIGHT. LIGHT/OCCASIONALLY MODERATE SNOW CONTINUES IN BROAD CYCLONICALLY CURVED BAND OF ISENTROPIC UPGLIDE FROM SOUTHERN OHIO VALLEY AND LOWER GREAT LAKES INTO WI/NORTHERN IL/IA. AS MENTIONED IN MIDDAY AFD UPDATE...AREAS TO WATCH FOR ENHANCED SNOWFALL ARE ACROSS COUNTIES BORDERING LAKE MICHIGAN WHERE COMBINATION OF LOW LEVEL CONVERGENCE AND STEEP LAPSE RATES HELPING TO MAINTAIN STRONGER REFLECTIVITIES AND LOWER OBSERVED VISIBILITIES...AND ACROSS PORTIONS OF I-80/I-88 CORRIDORS OVER WESTERN COUNTIES WHERE LOW LEVEL FRONTOGENESIS MAXIMA OCCURRING NORTH OF SHARP LOW LEVEL BAROCLINIC ZONE ASSOCIATED WITH SFC TROUGH AXIS. RADAR TRENDS APPEAR TO CONFIRM IDEA OF LAKE ENHANCED SNOWFALL AFFECTING PORTIONS OF NORTHEAST IL/CHI METRO AREA THROUGH THE REMAINDER OF THE AFTERNOON/EVENING RUSH HOUR...WITH MODERATE/HEAVY SNOW AT TIMES CURRENTLY OVER NORTHERN SUBURBS GRADUALLY SHIFTING SOUTH ACROSS THE CITY BY EVENING AND INTO NORTHWEST INDIANA OVERNIGHT. RECENT REPORT OF 7 INCHES IN LAKE COUNTY IL SUGGESTS GOING 8-12 INCH STORM TOTAL FOR LAKE MICHIGAN COUNTIES STILL APPROPRIATE. HAVE MADE ONLY MINOR TWEAKS ELSEWHERE WITH STRENGTHENING DEFORMATION/FRONTOGENETIC BAND TO SUPPLY SEVERAL MORE HOURS OF SNOW TO REMAINDER OF FORECAST AREA INTO THIS EVENING. EVENING PHASE OF STORM WILL BE ACCOMPANIED BY INCREASING NORTH/NORTHWEST WINDS TONIGHT AS SFC LOW CONTINUES TO DEEPEN FOR A TIME OFF TO OUR EAST. SUSTAINED WINDS APPROACHING 20 KTS WITH GUSTS NEAR/AROUND 30 KTS EXPECTED OVERNIGHT ESPECIALLY ACROSS SOUTHEASTERN PORTION OF CWA...WITH BLOWING AND DRIFTING OF SNOW EXPECTED TO BECOME WIDESPREAD ACROSS THE AREA TONIGHT. WHILE CONDITIONS SUGGEST WE MAY APPROACH BLIZZARD CONDITIONS IN A FEW SPOTS AT TIMES... CONFIDENCE IN MEETING BLIZZARD WARNING CRITERIA OF 3 HOURS OF 35 MPH AND 1/4SM VISIBILITY NOT HIGH ENOUGH TO UPGRADE TO BLIZZARD WARNING...ESPECIALLY WITH SLIGHTLY LOWER SNOW/LIQUID RATIOS EARLIER IN THE DAY AND SNOW WINDING DOWN AS WINDS REALLY PICK UP TONIGHT. THEREFORE WILL LET WINTER STORM WARNING RIDE WITH EMPHASIS ON BLOWING/DRIFTING AND POOR VISIBILITY. LINGERING LAKE EFFECT INTO PORTER COUNTY LATE TONIGHT/WEDNESDAY MORNING...THOUGH FORECAST SOUNDINGS OVER SOUTHERN LAKE MICHIGAN INDICATE INVERSION HEIGHTS/EQUILIBRIUM LEVELS DECREASING RAPIDLY DURING THE MORNING WEDNESDAY. AT THIS TIME HAVE MAINTAINED SNOW AMOUNTS FROM PREVIOUS FORECAST FOR LAKE SNOW BELT AREAS...WITH 10 TO 15 INCHES ACROSS NORTHEAST PORTER COUNTY BY THE TIME IT TAPERS OFF WEDNESDAY AFTERNOON. RATZER LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY... AT 500 MB...A NORTHWEST FLOW WILL CONTINUE OVER NORTHERN ILLINOIS AND NORTHWEST INDIANA WEDNESDAY NIGHT THROUGH FRIDAY. A 500 MB TROUGH IS FORECAST TO MOVE INTO MINNESOTA BY FRIDAY EVENING. THIS TROUGH WILL MOVE THROUGH ILLINOIS FRIDAY AFTERNOON. WE WILL FORECAST A CHANCE OF SNOW FRIDAY. ANOTHER 500 MB TROUGH IS FORECAST TO MOVE THROUGH ILLINOIS LATE SATURDAY NIGHT AND SUNDAY MORNING. THIS TROUGH IS FORECAST TO BE MORE INTENSE THAN THE ONE THAT OCCURRED FRIDAY. A SURFACE LOW WILL DEVELOP IN IOWA SATURDAY EVENING AND WILL MOVE ACROSS CENTRAL ILLINOIS SUNDAY. THEN BY SUNDAY EVENING THE SURFACE LOW WILL BE IN SOUTHERN OHIO. ANOTHER HIGH WILL MOVE INTO THE MISSISSIPPI VALLEY MONDAY NIGHT. WE USED THE GFS MODEL FOR GUIDANCE AND FOR TEMPERATURES...WE FOLLOWED MOS GUIDANCE. FOR THE LAST SEVEN DAYS THE MEAN ABSOLUTE ERRORS WERE LOWER THAN THE GFS MOS GUIDANCE. THE FORECAST HIGH TEMPERATURES WILL BE IN THE MIDDLE TO UPPER 20S THURSDAY THROUGH MONDAY. THE FORECAST LOW TEMPERATURES WILL BE IN THE TEENS SATURDAY THROUGH TUESDAY. WW && .AVIATION... 1111 PM CST 0600 UTC TAFS...LAKE EFFECT HAS COMPLETED TRANSITION TO SINGLE BAND EXTENDING FROM MID CENTRAL PORTION OF LAKE MI SSW TO ALONG THE SE WI AND NE IL SHORES. FLOW TO CONTINUE TO BACK THROUGH THE OVERNIGHT RESULTING IN TAIL END OF BAND SHIFTING GRADUALLY EASTWARD ACROSS THE IND STATE LINE. WINDS HAVE PICKED UP BUT STRONG GUSTS HAVE YEST TO MAKE IT INTO THE IMMEDIATE CHI AREA. WHILE SFC LOW OVER FAR WEST END OF LAKE ERIE WILL CONTINUE TO WEAKEN...THE RIDGE EXTENDING FROM CENTRAL CANADA S ACROSS THE PLAINS TO EAST TX WILL CONTINUE TO SHIFT EAST MAINTAINING PRESSURE GRADIENT AT LEAST INTO WED MORNING SO WHILE LIGHT SYNOPTIC SNOW AND MODERATE TO HEAVY LAKE EFFECT WILL BE ENDING...SOME EPISODES OF BLOWING SNOW EXPECTED TO PRODUCE RESTRICTED VISIBILITIES THROUGH FIRST PART OF WED MORNING. PATCHY MVFR STRATOCU UPSTREAM TO NW WI AND SE MN THEN MAINLY SKC. WITH DEEP NW FLOW BY WED EVE ALONG WITH RIDGE AXIS MOVING TO UPPER MS AND LOWER MO VALLEYS EXPECT CLOUDS TO CLEAR OUT BY LATE AFTERNOON-EARLY EVENING. WINDS TO ALSO GRADUALLY DIE OFF AS LOW TO THE EAST FILLS AND RIDGE NEARS. TRS && .MARINE... 139 PM...PRIMARY FORECAST CONCERN REMAINS GALES THRU WEDNESDAY EVENING. OVERALL...NO MAJOR CHANGES TO GOING FORECAST/GRIDS. A LARGE RIDGE OF HIGH PRESSURE EXTENDS FROM HUDSON BAY SOUTHWEST ACROSS THE NORTHERN AND CENTRAL PLAINS. THIS RIDGE WILL WEAKEN AS IT SLOWLY SHIFTS EAST WEDNESDAY AND WEDNESDAY NIGHT AND BECOMES CENTERED OVER THE OHIO RIVER VALLEY THURSDAY NIGHT. AHEAD OF THIS RIDGE IS AN AREA OF LOW PRESSURE LIFTING NORTHEAST ACROSS OHIO. THIS LOW WILL DEEPEN FURTHER AS IT REACHES LAKE ERIE THIS EVENING...THEN NEW LOW PRESSURE WILL DEVELOP OFF THE MID ATLANTIC COAST AND RAPIDLY DEEPEN TONIGHT...ABSORBING THE LOW OVER LAKE ERIE. AS A RESULT...NORTHEAST WINDS WILL CONTINUE TO INCREASE THRU THIS EVENING INCREASING TO GALES. WINDS WILL TURN MORE NORTHERLY AFTER MIDNIGHT THEN TURN NORTHWEST WEDNESDAY MORNING. THE GRADIENT WILL SLOWLY WEAKEN...ESPECIALLY AFTER THE LOW OVER LAKE ERIE WEAKENS AND IS ABSORBED. THUS GALES WILL DIMINISH WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING. BUT SINCE THE HIGH WILL RE-CENTER ITSELF OVER THE OHIO VALLEY...THE GRADIENT WILL REMAIN TIGHT ACROSS THE WESTERN LAKES THROUGH THURSDAY MORNING...THUS WINDS WILL REMAIN STRONG WEDNESDAY NIGHT. STILL SOME UNCERTAINTY REGARDING THE NEXT SYSTEM TO AFFECT THE LAKES REGION THIS WEEKEND. LOW PRESSURE IS EXPECTED TO MOVE ACROSS THE SOUTHERN LAKES REGION WITH ANOTHER STRONG HIGH BUILDING ACROSS THE PLAINS. HOWEVER...WIND SPEEDS WILL BE DEPENDENT ON THE STRENGTHEN/LOCATION OF THE LOW AND WITH LOW CONFIDENCE FROM THIS DISTANCE...WILL KEEP WINDS IN THE 15-25KT RANGE FOR NOW. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010- ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022- ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 9 AM WEDNESDAY. IN...WINTER STORM WARNING...INZ001-INZ002-INZ011 UNTIL NOON WEDNESDAY. WINTER STORM WARNING...INZ010-INZ019 UNTIL 9 AM WEDNESDAY. LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ743-LMZ744- LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 PM WEDNESDAY. GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567- LMZ740-LMZ741-LMZ742-LMZ868 UNTIL 4 PM WEDNESDAY. && $$
