412 AM CDT
FOCUS OF FORECAST IS ON PAIR OF SYSTEMS TO AFFECT THE AREA...THE
FIRST ONE SOMEWHAT INDIRECTLY TODAY THROUGH MONDAY AND THE SECOND
ONE MORE DIRECTLY MONDAY NIGHT THROUGH LATE WEEK. MODELS ARE
SHOWING GOOD CONTINUITY WITH THEIR PREVIOUS RUNS AND ALSO IN GOOD
AGREEMENT AS FAR OUT AS TUESDAY AND WEDNESDAY WITH THE ECMWF BEING
A BIT SLOWER THAN OTHER MODELS IN MOVING THE SECOND SYSTEM ACROSS
THE CENTRAL THE CENTRAL U.S.
THE FIRST SYSTEM IS CURRENTLY OVER THE SENORAN DESERT WITH A
SURFACE TOUGH DEEPENING DOWNSTREAM OVER THE ROCKIES AND HIGH
PLAINS. SATELLITE LOOPS SHOW AN UPPER LOW CIRCULATION ALREADY
FORMING AT THE BASE OF THE TROUGH OVER WESTERN AZ. WITH THE
UPPER TROUGH AND LOW PROGGED TO MOVE NE AND OVER THE CENTRAL HIGH
PLAINS BY THIS EVENING AND THEN NNE ACROSS THE NORTHERN PLAINS TO
NEAR THE CANADIAN BORDER BY 12Z SUN THE ASSOCIATED SURFACE LOW
WILL TRACK SEVERAL HUNDRED MILES WELL OFF TO THE NW OF THE LOCAL
AREA. ITS INFLUENCE WILL BE FELT THOUGH AS THE GRADIENT INCREASES
BETWEEN THE DEEPENING LOW LIFTING ACROSS THE DAKOTAS AND THE LARGE
SURFACE RIDGE PARKED OVER THE E FROM NEW ENGLAND SW ACROSS THE MID
ATLANTIC STATES...THE DEEP S AND THE NORTHERN GULF OF MEXICO.
THIS RETURN FLOW AND THE ASSOCIATED WARM AIR ADVECTION ON THE
BACK SIDE OF THE RIDGE IS ALREADY WELL UNDERWAY WITH 88D AND
PROFILER MEASUREMENTS OF S-SSW 35-45 KT FLOW FROM TX NORTHEASTWARD
ALL THE WAY ACROSS THE UPPER MIDWEST. BASED ON MAX TEMPERATURES
LOCALLY FRI...MOST OF THE FORECAST AREA WILL SEE UPPER 50S OR
LOWER 60S THIS AFTERNOON UNDER JUST SOME CIRRUS CLOUDS.
AS THE FIRST SYSTEM CONTINUES ON SOUTHERN HUDSON BAY DURING MON A
WEAK TRAILING COLD FRONT WILL SAG S INTO NORTHERN IL. THIS
BOUNDARY BECOMES STATIONARY ACROSS THE FORECAST AREA MON NIGHT AS
THE SECOND SYSTEM...CURRENTLY OVER THE EASTER PACIFIC NEAR 130W
45N...MOVES TO SOUTHERN AND CENTRAL ROCKIES. SINCE MOISTURE WILL
NOT BE ABUNDANT...THOUGH SOME LOWER LEVEL MOISTURE SEEN UPSTREAM
WITH DEW POINTS IN THE 40S AND A STRATUS DECK OVER THE OZARKS
ADVECTING NORTHWARD...AND THE ONLY FORCING WILL BE CONVERGENCE
ALONG THE BOUNDARY AND THE BEGINNINGS OF WEAK LOW LEVEL
ISENTROPIC LIFT HAVE KEPT POP VALUES IN THE SLIGHT CHANCE AND LOW
END CHANCE RANGE FOR SUN NIGHT INTO MON.
BY MON NIGHT THE SECOND SYSTEM WILL BE MOVING FROM THE ROCKIES TO
THE PLAINS. WHILE THE SURFACE RIDGE ACROSS THE NORTHERN GULF KEEPS
DEEP MOISTURE AT BAY EVENTUALLY WORK ITS WAY NORTHWARD AHEAD OF
THIS SYSTEM. THERE WILL BE MUCH STRONGER DYNAMICS LOCALLY WITH
THIS SYSTEM AS IT IS PROGGED TO LIFT ACROSS THE MID MS VALLEY TUE
NIGHT AND WED AND RIGHT OVER THE LOCAL AREA LATER WED AND WED
NIGHT AS IT CONTINUES ON ITS WAY TO THE WESTERN GREAT LAKES AND
LOWER OH VALLEY BY THU. WITH A GOOD SUPPLY OF MOISTURE EVENTUALLY
ARRIVING ACROSS THE REGION MON NIGHT AND TUE AS STRONG SW FLOW
PERSISTS AHEAD OF THE STORM SYSTEM WIDESPREAD OVER-RUNNING IS
ANTICIPATED TO BREAK OUT ALONG AND N OF THE BOUNDARY WITH SHOWERS
AND THUNDERSTORMS S. THERE WILL LIKELY BE SOME EMBEDDED ELEVATED
CONVECTION ACROSS THE NORTHERN PORTION OF THE FORECAST AREA
POSSIBLE OVERNIGHT MONDAY BUT MORE LIKELY DURING TUE WITH STEEP
MID LEVEL LAPSE RATES AND STRONG...DEEP UPWARD VERTICAL MOTION
UNDERWAY.
MODELS SHOWING A WEDGE OF DRY AIR QUICKLY WRAPPING INTO THE SYSTEM
DURING WED AND EXPECT MOIST PRECIPITATION TO BE OVER FOR THE MOST
PART BY WED NIGHT. MODELS DO SHOW A WEDGE OF HIGHER MOISTURE
ACCOMPANYING THE MAIN UPPER TROUGH ACROSS THE AREA DURING LATE
WED-WED NIGHT SO MAY SEE SOME LIGHT RAIN SHOWERS UNDER THE UPPER
TROUGH WED NIGHT PUT ONLY HAVE CARRIED SLIGHT CHANCES. TEMPERATURE
PROFILES AND THICKNESS PROGS STILL SUGGEST THERE MAY BE SOME LIGHT
SNOW MIXED IN WITH THE SHOWERS ACROSS THE NORTHERN PORTION OF THE
FORECAST AREA.
AFTER THIS MAIN UPPER TROUGH MOVES E OF THE AREA BY THU MORNING
THE AREA IS TO UNDER A WNW FLOW WITH THE SOURCE REGION OF THE
AIR MASS BEING THE NORTHERN PACIFIC BUT A DEEP UPPER TROUGH REMAINS
OVER EASTERN NORTH AMERICA THROUGH FRI BEFORE MOVING OFF THE
CAROLINA COAST. THIS WILL KEEP THE LOCAL AREA COOL WITH HIGHS ONLY
IN THE MID AND UPPER 40S THU AND FRI.
TRS
&&
.FIRE WEATHER...
243 PM CDT
STRONG SOUTHERLY WINDS AND UNSEASONABLY WARM CONDITIONS ARE
LIKELY SUNDAY AFTERNOON. AS IS OFTEN THE CASE...THERE ARE
QUESTIONS REGARDING HOW QUICKLY DEW POINTS WILL RISE AS MOISTURE
RETURNS NORTHWARD. CURRENTLY LOOKS LIKELY THAT RELATIVE HUMIDITY
VALUES WILL REMAIN ABOVE RED FLAG THRESHOLDS...HOWEVER SOUTH WINDS
OF 20-30 MPH WITH GUSTS POSSIBLY UP TO 40 MPH WITH RH POSSIBLY
DROPPING BELOW 40 PERCENT COULD STILL RESULT IN HEIGHTENED FIRE
DANGER. THE GREATEST FIRE DANGER/LOWEST RH VALUES ARE EXPECTED
SOUTHEAST OF I-55 IN ILLINOIS INTO NORTHWEST INDIANA.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* NO CONCERNS THRU DAYBREAK.
* WINDS STEADILY INCREASE AND BECOME GUSTY FROM THE
SOUTH/SOUTHEAST MIDDAY FROM 18 TO 22KT.
BEACHLER
//DISCUSSION...UPDATED 06Z...
IR IMAGERY EARLY THIS MORNING SHOWS A NARROW CHANNEL OF CIRRUS
FLOATING OVERHEAD. SFC HIGH PRESSURE CENTER HAS DRIFTED EAST OF
NORTHERN IL/NORTHWEST IN...ALLOWING WINDS TO TURN SOUTHEASTERLY.
A STORM SYSTEM WILL PUSH INTO THE PLAINS STATES TODAY AND ALLOW THE
PRESSURE GRADIENT TO TIGHTEN THROUGHOUT THE DAY TODAY ACROSS THE
WESTERN GREAT LAKES REGION. THIS GRADIENT IS EXPECTED TO PRODUCE
WIND GUSTS THROUGHOUT THE AFTN BETWEEN 18 AND 24KT FOR AIRFIELDS
IN NORTHERN IL/NORTHWEST IN. ARND SUNSET GUSTY WINDS WILL
DIMINISH...HOWEVER THE SOUTHERLY WINDS ARND 10KT WILL PERSIST THRU
DAYBREAK SUN. MINIMAL CLOUD COVER IS EXPECTED THROUGHOUT THE TAF
PERIOD...AS CONISDERABLE DRY AIR WILL REMAIN IN PLACE.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* HIGH CONFIDENCE IN ALL ELEMENTS.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...WINDY. SOUTHERLY WINDS GUSTING 30 KT. SLIGHT CHANCE OF
SHRA SUNDAY NIGHT. VFR.
MONDAY...SHRA DEVELOPING MONDAY EVENING. TSRA/MVFR CIGS POSSIBLE
MONDAY NIGHT.
TUESDAY...SHRA/TSRA LIKELY. MVFR CIGS POSSIBLE.
WEDNESDAY...SHRA THROUGH AFTERNOON. MVFR POSSIBLE.
THURSDAY...VFR.
&&
.MARINE...
400 AM CDT
RIDGE OF HIGH PRESSURE CONTINUES TO DRIFT EAST AND WILL GRADUALLY
STRENGTHEN AS IT BECOMES CENTERED OVER THE MIDDLE ATLANTIC REGION.
THIS RIDGE WILL THEN STRETCH FROM SOUTHERN QUEBEC SOUTH THROUGH
THE GULF OF MEXICO STATES. MEANWHILE A LOW PRESSURE SYSTEM IS
EXPECTED TO STRENGTHEN ACROSS THE ROCKIES...LIFTING NORTHEAST
TOWARDS THE WESTERN DAKOTAS SUNDAY. BETWEEN THESE TWO SYSTEMS THE
PRESSURE GRADIENT IS EXPECTED TO STEADILY INCREASE...ALLOWING SFC
WINDS TO INCREASE. WINDS THIS MORNING OVER LAKE MICHIGAN HAVE
ALREADY COME UP INTO THE TEENS TO LOWER 20 KT RANGE FROM THE
SOUTHEAST. IT APPEARS THE WIND DIR WILL REMAIN OUT OF THE
SOUTHEAST FOR THE SOUTHERN PORTIONS OF LAKE MICHIGAN
TODAY...EVENTUALLY TURNING SOUTH.
FOR THE NEARSHORE WATERS HAVE BUMPED UP THE TIMING FOR THE SMALL
CRAFT ADVISORY MAINLY DUE TO THE LENGTH IN TIME OF SOUTH/SOUTHEAST
FLOW. WINDS/WAVES SHOULD FLIRT WITH CRITERIA THIS
AFTERNOON...HOWEVER FEEL THAT KEEPING THE ADVISORY CONFINED TO THE
ILLINOIS NEARSHORE WATERS FOR TONIGHT WAS BEST. GUIDANCE CONTINUES
TO SHOW A DIFFERENCE OF IDEAS...SO CONFIDENCE REMAINS LOW FOR
TODAY ON WINDS/WAVES.
THEN WINDS STEADILY INCREASE TO GALE CRITERIA SUNDAY MORNING FOR
THE OPEN WATERS OF LAKE MICHIGAN...WITH THE HIGHEST WINDS EXPECTED
TO OCCUR OVER THE NORTHERN/CENTRAL PORTIONS OF LAKE MICHIGAN WITH
GALES NEAR 40 KT SUNDAY MIDDAY. MEANWHILE THE NEARSHORE WATERS WILL PUSH
INTO THE 20 TO 25 KT RANGE...SUPPORTING THE SMALL CRAFT ADVISORY.
WINDS APPEAR TO BEGIN TO DIMINISH LATE SUNDAY NIGHT. SO AT THIS
POINT AN EXTENSION IN TIME TO THE HEADLINES IS NOT NEEDED.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...7 PM SATURDAY TO 9 PM
SUNDAY.
SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744-LMZ745...3 AM SUNDAY
TO 9 PM SUNDAY.
GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...6 AM SUNDAY TO 9 PM
SUNDAY.
&&
$$
