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 12Z...
* SOUTHEAST WINDS STEADILY INCREASING WITH GUSTS BETWEEN 18 AND 22
KT.
* WINDS GRADUALLY TURN TO THE SOUTH OVERNIGHT AND DIMINISH TO
AROUND 10 KT OVERNIGHT.
BEACHLER
//DISCUSSION...UPDATED 12Z...
IR IMAGERY THIS MORNING CONTINUES TO SHOW A REGION OF CIRRUS
CLOUDS FLOATING NORTHEAST ACROSS THE WESTERN GREAT LAKES REGION
STRETCHING SOUTH THROUGH THE MISSOURI VALLEY. HIGH PRESSURE HAS
DRIFTED EAST ACROSS THE EASTERN PORTIONS OF THE OHIO VALLEY AND
WILL ELONGATE FROM SOUTHERN QUEBEC TO THE GULF OF MEXICO THEN
BEGIN TO STRENGTHEN. MEANWHILE AN AREA OF LOW PRESSURE CURRENTLY
OVER THE CENTRAL ROCKIES WILL STEADILY DEEPEN AND LIFT NORTHEAST
TOWARDS THE WETERN DAKOTAS. AS THIS LOW PRESSURE LIFTS
NORTHEAST THE PRESSURE GRADIENT WILL STEADILY TIGHTEN ALONG THE
LEE-SIDE OR ACROSS THE EASTERN PLAINS AND WESTERN GREAT
LAKES. THIS INCLUDES NORTHERN ILLINOIS AND NORTHWEST INDIANA
AIRFIELDS. WINDS TODAY WILL STEADILY INCREASE FROM THE SOUTHEAST
TO AROUND 15KT SUSTAINED. MIXED LAYER WILL ALSO BRING TO THE SFC
WIND GUSTS UP TO 22 KT...SLIGHTLY HIGHER FURTHER WEST. FOR NOW
HAVE ADJUSTED TAF ACCORDINGLY TO REFLECT THIS. MINIMAL CLOUDS
OTHER THAN SOME CIRRUS FLOATING OVERHEAD TODAY. OVERNIGHT WINDS
WILL DIMINISH TO AROUND 10KT AND BECOME MORE SOUTHERLY. THEN EARLY
SUNDAY WINDS BECOME SOUTHWESTERLY AND STEADILY INCREASE YET AGAIN.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...VFR. GUSTY WINDS UP TO 30KT EARLY. CHC OF SHRA
LATE.
MONDAY...VFR. CHC SHRA MAINLY LATE. ISO TSRA WITH MVFR CIGS.
TUESDAY...MVFR. SHRA/ISO TSRA.
WEDNESDAY...MVFR TRENDING VFR. SHRA.
THURSDAY...PATCHY MVFR. SHRA PSBLY MIXED SN.
FRIDAY...VFR.
BEACHLER
&&
.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.
&&
$$
