340 AM CDT
WEAKENING SURFACE LOW PRESSURE WAS LIFTING NORTH ACROSS NORTHEAST
WISCONSIN EARLY THIS MORNING...WITH TRAILING OCCLUDED COLD FRONT
ABOUT TO PUSH EAST OF THE CWA. LINGERING LIGHT SHOWERS WITH FRONT
SHOULD EXIT BY 12Z. PATCHY FOG HAS DEVELOPED IN SOME SPOTS WHERE
SKIES HAVE CLEARED OVER MOIST GROUND...HOWEVER CLOUDS MOVING BACK
INTO WESTERN ILLINOIS WILL LIKELY KEEP FOG FROM BECOMING TOO
WIDESPREAD THIS MORNING. SUBSIDENCE WILL INCREASE LATER THIS MORNING
AS UPPER TROUGH MOVES OFF...AND RIDGING BUILDS IN TO THE AREA THIS
AFTERNOON. THIS SHOULD ALLOW DECREASING CLOUD COVER BY THIS
AFTERNOON.
SOUTHERLY FLOW DEVELOPS LATER TONIGHT AFTER WEAK SURFACE HIGH
PRESSURE RIDGE PASSES ACROSS THE FORECAST AREA LATE THIS
AFTERNOON/EARLY THIS EVENING. WARM ADVECTION DEVELOPS IN EARNEST BY
EARLY TUESDAY...AHEAD OF POSITIVE TILT UPPER TROUGH DEVELOPING
ACROSS THE NORTHERN CONUS. DRY AIR AND LOW LEVEL THERMAL RIDGE
SHOULD HELP TO PUSH TEMPS INTO THE LOWER AND MIDDLE 60S
TUESDAY...MORE ALONG THE LINES OF THE WARMER MET GUIDANCE.
UPPER TROUGH DIGS ACROSS THE CENTRAL CONUS TUESDAY NIGHT AND
WEDNESDAY. NORTHERN STREAM SHORT WAVE PASSING NORTH OF THE GREAT
LAKES TRAILS A SLOW MOVING COLD FRONT ACROSS WISCONSIN AND EASTERN
IOWA TUESDAY NIGHT...AND ACROSS LAKE MICHIGAN AND ILLINOIS ON
WEDNESDAY. GUIDANCE IS IN GOOD AGREEMENT IN DEVELOPING PRECIP ON THE
COOL SIDE OF THE BAROCLINIC BOUNDARY...THOUGH VARIOUS MODELS ARE A
LITTLE DIFFERENT IN HOW FAR THE FRONT PUSHES INTO THE WFO LOT CWA.
THE GREATER CHANCE OF PRECIPITATION WILL BE ACROSS THE NORTHWEST
PART OF THE FORECAST AREA WEDNESDAY...AND HAVE BASED POPS MORE ALONG
SLOWER ECMWF/WRF SOLUTIONS AT THIS POINT.
SHORT WAVE MOVING INTO THE SOUTHERN PART OF THE TROUGH IS PROGGED
TO DEVELOP A CLOSED UPPER LOW ACROSS KANSAS AND MISSOURI WEDNESDAY
NIGHT...WITH RAIN SPREADING ACROSS THE REMAINDER OF THE CWA AS
BAROCLINIC ZONE NORTH OF SURFACE FRONT BECOMES FOCUS FOR DEVELOPING
DEFORMATION ZONE INTO THURSDAY. SURFACE LOW QUICKLY OCCLUDES AND
MOVES INTO THE LOWER OHIO VALLEY THURSDAY NIGHT...WITH PRECIP
DIMINISHING FROM NORTHWEST TO SOUTHEAST ACROSS THE CWA.
HIGH PRESSURE THEN SPREADS ACROSS THE GREAT LAKES REGION FRIDAY AS
UPPER RIDGE DEVELOPS ALOFT...AND DEEP TROUGH TAKES SHAPE OVER THE
WESTERN CONUS IN A CONTINUATION OF HIGH AMPLIFIED UPPER AIR PATTERN.
GFS/ECMWF IN PRETTY GOOD AGREEMENT IN A NEGATIVE TILT SHORT WAVE AND
ASSOCIATED DEEP SURFACE LOW LIFTING NORTHEAST ACROSS THE PLAINS AND
INTO WESTERN MINNESOTA ON SATURDAY. THIS IS EXPECTED TO RESULT IN
GUSTY SOUTH WINDS...WITH ANOTHER SHOT OF STRONG WARM ADVECTION. HAVE
BUMPED MAX TEMPS A BIT FOR SATURDAY...IN LINE WITH 00Z MEX GUIDANCE
WHICH IS AT THE HIGH END OF THE ENSEMBLE ENVELOPE. MAY EVENTUALLY
NEED TO RAISE TEMPS MORE...AS LOCATION OF THERMAL RIDGE AND DIURNAL
TIMING COME INTO BETTER FOCUS. OCCLUDED COLD FRONT PUSHES THROUGH
THE FORECAST AREA SATURDAY NIGHT AND SUNDAY...WITH RELATIVELY LOW
CHANCE ATTENDANT POPS. NO REAL PUSH OF REALLY COLD AIR SEEN AT THIS
DISTANCE INTO EARLY NEXT WEEK.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 10Z...
* DEVELOPING FOG WITH POSSIBLE VIS OF 3-5SM OVER THE NEXT COUPLE
OF HOURS.
* VFR CEILINGS TO MOVE BACK OVER THE TERMINALS LATER THIS MORNING.
RODRIGUEZ
//DISCUSSION...UPDATED 06Z...
WEAKENING LOW PRESSURE CONTINUES TO MOVE NORTHEASTWARD TOWARD
NORTHERN LAKE MICHIGAN TONIGHT WITH A FRONTAL BOUNDARY APPROACHING
FROM THE WEST. SOUTH WINDS WILL TURN WEST YET TONIGHT AND INCREASE
SLIGHTLY LATER MONDAY MORNING. MAIN ISSUE WILL BE CIGS. VFR CIGS
ARE STARTING TO SCATTER FROM THE WEST BUT AN EXPANSIVE AREA OF VFR
CIGS IS SPREADING EASTWARD FROM IOWA AND IS EXPECTED TO MOVE
OVERHEAD OVERNIGHT. MAIN QUESTION WILL BE WHETHER THESE CLOUDS
REMAIN IN PLACE THROUGH DAYBREAK AND LOWER OR IF NEW STRATOCU
DEVELOPMENT WILL OCCUR DURING THE LATE MORNING...FOLLOWING
SCATTERING OF THE OVERNIGHT DECK...WITH BASES AROUND 3000 FT THEN
LIFT INTO THE AFTERNOON. WEST TO SOUTHWEST WINDS WILL TURN
SOUTHERLY MONDAY EVENING WITH ONLY SOME HIGH CIRRUS EXPECTED.
ONE OTHER POTENTIAL ISSUE IS FOG DEVELOPMENT TONIGHT THANKS TO HE
RAIN THAT FELL EARLIER. INDICATED PATCHY/SHALLOW FOG AT DPA/RFD
BUT CANNOT COMPLETELY RULE OUT AT THE REMAINING SITES BUT
RETURNING CLOUD COVER MAY MITIGATE THIS.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 10Z...
* HIGH CONFIDENCE OF OBSERVING FOG WITH MEDIUM CONFIDENCE OF VIS
TRENDS.
* HIGH CONFIDENCE WITH VFR CEILINGS MOVING BACK OVER THE TERMINALS
WITH MEDIUM CONFIDENCE AS TO THE EXACT TIMING.
* HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY...VFR.
WEDNESDAY...VFR WITH SHRA ARRIVING WEDNESDAY NIGHT WITH MVFR
POSSIBLE.
THURSDAY...SHRA WITH MVFR POSSIBLE.
FRIDAY...VFR.
SATURDAY...VFR...CHANCE OF SHRA.
MDB
&&
.MARINE...
255 AM CDT
LOW PRESSURE ACROSS NORTHEASTERN WISCONSIN WILL MOVE INTO WESTERN
SUPERIOR THIS MORNING...BEFORE WEAKENING INTO AN OPEN TROUGH.
WINDS WILL INCREASE TOMORROW OUT OF THE SOUTH AS THE GRADIENT
TIGHTENS WITH HIGH PRESSURE EXITING TO THE EAST AND A COLD FRONT
ADVANCING FROM THE WEST. WINDS WILL LIKELY INCREASE AND PEAK JUST
BELOW GALES FOR THE OPEN WATERS...AND A SMALL CRAFT ADVISORY MAY
BE NEEDED FOR THE AFTERNOON AND EARLY EVENING HOURS ON TUESDAY FOR
THE NEARSHORE WATERS. THE COLD FRONT WILL THEN SWEEP ACROSS THE LAKE
FLIPPING WINDS AROUND TO THE NORTH OVERNIGHT ON WEDNESDAY. A WEAK
SHOT OF COLD AIR ADVECTION WILL BRING UP THE CHANCES FOR NORTHERLY
GALES ACROSS THE SOUTHERN HALF OF THE LAKE AT THAT TIME. HIGH
PRESSURE WILL THEN BUILD ACROSS THE LAKES TOWARDS THE END OF THE
WEEK AND INTO THE WEEKEND.
SHEA
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
