1001 AM CDT
CHALLENGING FORECAST FOR THE REMAINDER OF THE DAY TODAY...IN
REGARDS TO LINGERING DRY AIR AND PRECIP CHANCES. IR IMAGERY THIS
MORNING CONTINUES TO INDICATE THIN POCKETS IN THE CLOUD
SHIELD...WHICH INDICATES LINGERING DRY AIR IN THE ATMOSPHERE.
REGIONAL RADAR MOSAIC CONTINUES TO DEPICT A CHANNEL OF SHOWERS
EXTENDING FROM ST LOUIS NORTH THROUGH WESTERN ILLINOIS AND INTO
WESTERN WISCONSIN. THIS AREA OF RAIN WAS SLIDING EAST...HOWEVER
RECENT TRENDS HAVE INDICATED THAT THE LEADING EDGE WAS ERODING
SLOWLY AS IT PUSHES INTO A MUCH DRIER ENVIRONMENT ACROSS
NORTHCENTRAL ILLINOIS. DEW PT DEPRESSIONS REMAIN LARGE ACROSS MOST
OF THE CWFA...ON THE ORDER OF 20 DEG. THE EXCEPTION IS EXTREME
NORTHCENTRAL AND NORTHWEST ILLINOIS WHERE DEPRESSIONS ARE IN THE
TEENS.
500MB TROUGH AXIS REMAINS UPSTREAM THIS MORNING...HOWEVER GUIDANCE
CONTINUES TO PUSH THIS FEATURE OVER FAR WESTERN ILLINOIS BY
MIDDAY. THEN CONTINUE TO PUSH EAST. ALONG THE LEE-SIDE OF THE
TROUGH A TONGUE OF DEEPER MOISTURE IS PROGGED...AND APPEARS TO BE
ARRIVING OVER THE CWFA ARND 21Z AND QUICKLY PUSHES NORTHEAST BY
00Z. HAVE MADE SOME ADJUSTMENTS TO LOWER QPF TOTALS GIVEN THE DRY
AIR INFLUENCE. TEMPS ALSO BROUGHT DOWN A COUPLE OF DEGREES IN
SPOTS...BUT OVERALL STILL LOOKS TO BE FROM AROUND 50 TO THE MID
50S.
BEACHLER
&&
.PREV DISCUSSION...
347 AM CDT
MAIN CONCERNS/ISSUES ARE WITH PRECIP TRENDS TODAY INTO
TONIGHT...ALONG WITH A WARMING TREND ANTICIPATED THROUGH THE
MIDDLE PART OF THE WEEK.
LATEST SATELLITE IMAGERY DEPICTING CURRENT LONGWAVE TROUGH ACROSS
THE CENTRAL PLAINS DIGGING SOUTH ALONG WITH ATTENDANT SURFACE
TROUGH AND ASSOCIATED FRONTAL BOUNDARIES LOCATED NEAR
MINNESOTA/IOWA THIS MORNING. AS THESE FEATURES SHIFT EAST EARLY
THIS MORNING...SHOWERS CAN BE SEEN SPREADING EAST ACROSS PORTIONS
OF IOWA...AND EXPECT THESE SHOWERS AND CLOUD COVER TO MOVE EAST
ACROSS THE REGION WITH TIME TODAY. LATEST GUIDANCE IN FAIR
AGREEMENT WITH TAKING THIS UPPER LEVEL TROUGH AND SURFACE
REFLECTION EAST ACROSS SOUTHERN WISCONSIN BY LATER THIS AFTERNOON
INTO EARLY EVENING. AS THIS OCCURS...LARGE SCALE FORCING WILL
INCREASE MORE FROM WEST TO EAST ACROSS THE CWA WITH THE BEST
FORCING TO COME LATER THIS AFTERNOON. ALTHOUGH...LATEST SURFACE
OBSERVATIONS CONTINUE TO INDICATE A VERY DRY AIRMASS IN PLACE WITH
DEWPOINTS CURRENTLY IN THE MID 20S. LAST NIGHTS 00Z OBSERVED
SOUNDINGS FROM ACROSS THE AREA WERE ALSO SHOWING THIS DRY AIR MASS
WITH VERY DRY LOWER LEVELS. ALTHOUGH MOISTURE WILL BE ON THE
INCREASE INTO THIS AFTERNOON...DONT THINK THIS PRECIP SHIELD WILL
REALLY SHIFT OVERHEAD UNTIL THE MID TO LATE AFTERNOON. AS THIS
OCCURS...THE COLUMN WILL SATURATE AND MOST OF THE CWA SHOULD
OBSERVE SHOWERS. DID LOWER POPS JUST A LITTLE BRINGING THEM DOWN
TO LIKELY FOR THIS AFTERNOON...BUT DID NOT MAKE THIS CHANGE DUE TO
OVERALL CONFIDENCE. DID THIS MORE DUE TO THE FACT OF THIS DRIER
AIR IN PLACE AND THE POSSIBLE LIGHTER NATURE OF THESE SHOWERS IN
SOME PLACES. THE BEST CHANCES FOR PRECIP CONTINUE TO BE ACROSS THE
NORTHERN HALF OF THE CWA TIED CLOSER TO UPPER LEVEL TROUGH/SURFACE
LOW...WITH THESE AREAS ALSO OBSERVING MORE AMOUNTS. INSTABILITY
DURING THIS TIME FRAME WILL REMAIN NON EXISTENT ACROSS THE REGION
WITH PRECIP REMAINING SHOWERS. ALTHOUGH...LATEST HIGH RES DATA IS
HINTING AT THE POSSIBILITY OF SOME CONVECTIVE ELEMENTS FORMING ON
THE BACKSIDE OF THE MAIN PRECIP SHIELD...MORE TOWARDS THIS
EVENING. BASED ON LATEST DATA...THIS WOULD SEEM TO BE A SLIGHT
POSSIBILITY. MODELS INDICATING THAT DRIER AIR/STEEPER MID LEVEL
LAPSE RATES WILL POSSIBLY MOVE OVERHEAD DURING THIS TIME...THUS
CREATING CONVECTIVELY UNSTABLE CONDITIONS. AM NOT QUIET CONFIDENT
AS TO THESE EXACT DETAILS AT THIS TIME...SO HAVE OPTED TO LEAVE
OUT ANY MENTION OF THUNDER. A MORE LIKELY SCENARIO WOULD BE AN
INCREASE IN RAINFALL RATES AS OPPOSED TO ANY POSSIBLE THUNDER.
CLOSED UPPER LEVEL TROUGH LATE TONIGHT AND EARLY MONDAY SHOULD
BECOME MORE OPEN AND SLOWLY SHIFT EAST WITH TIME. SHOWERS WILL BE
ENDING DURING THIS TIME...BUT WITH CLOUD COVER TO POSSIBLY LINGER
INTO MONDAY AFTERNOON. THEN WITH THE DEPARTURE OF THIS UPPER LEVEL
TROUGH...RIDGING WILL BE ONGOING WITH A WARMER AIR MASS SHIFTING
OVER AND A DRY PERIOD EXPECTED INTO EARLY WEDNESDAY. WITH A STEADY
STREAM OF SOUTHERLY FLOW AND THERMAL AXIS SHIFTING ACROSS THE
REGION...HAVE RAISED POPS TUESDAY AND WEDNESDAY WITH HIGHS LOOKING
MORE LIKELY TO BE IN THE LOW TO MID 60S. WITH MODELS TRENDING MORE
TOWARDS A SLOWER PROGRESSION OF THE NEXT SYSTEM...WEDNESDAY TEMPS
AND CONDITIONS APPEAR TO BE ON THE UP. ALTHOUGH...FOR SURE
PRECIP/CLOUD COVER WILL BE ON THE INCREASE WEDNESDAY NIGHT INTO
THURSDAY AS THIS SYSTEM SHIFTS EAST.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 15Z...
* SOUTH WINDS GUSTING ABOVE 25 KTS TODAY.
* PERIOD OF SPRINKLES OR SHOWERS MID-AFTERNOON INTO EARLY
EVENING...HAVE SOME CONCERN THAT LOW LEVEL DRY AIR MAY MAKE
SHOWERS MORE SPOTTY AND NOT A PREVAILING CONDITION.
* CIGS LOWERING TO LOW END VFR...VERY LOW PROBABILITY OF BRIEF
MVFR IN SHRA.
RATZER
//DISCUSSION...UPDATED 12Z...
DEEPENING LOW PRESSURE DEVELOPING ALONG THE IOWA-MINNESOTA BORDER
THIS MORNING WILL RESULT IN INCREASINGLY GUSTY SOUTH WINDS
TODAY...IN ADDITION TO GRADUALLY LOWERING VFR CLOUD COVER AND
EVENTUALLY A PERIOD OF SHOWERS THIS AFTERNOON INTO EARLY THIS
EVENING. FORECAST SOUNDINGS INDICATE THE POTENTIAL FOR GUSTS
APPROACHING 30 KNOTS THIS AFTERNOON...AS MIXED LAYER DEEPENS WITH
DIURNAL WARMING. GUSTS SHOULD PICK UP BY MID-MORNING...BUT ARE
EXPECTED TO BE STRONGEST DURING THE EARLY-MID AFTERNOON HOURS.
WINDS WILL DECREASE TOWARD EVENING AS THE LOW BEGINS TO WEAKEN...
AND THE STRONGER WINDS ALOFT MOVE EAST OF THE TERMINALS. A COLD
FRONT/TROUGH WILL TRAIL THROUGH THE AREA THIS EVENING...WITH WINDS
SHIFTING TO THE SOUTHWEST WITH ITS PASSAGE.
MID AND HIGH CLOUD COVER IS ALREADY SPREADING ACROSS THE FORECAST
AREA THIS MORNING. LOW LEVELS ARE FAIRLY DRY ACROSS THE MIDWEST SO
DESPITE FAIRLY IMPRESSIVE LIFT WITH THIS SYSTEM...SATURATION AND
DEVELOPMENT OF PRECIP WILL TAKE SOME TIME. CURRENT BAND OF SHOWERS
OVER EASTERN IA AND NORTHEAST MO WILL CONTINUE TO MOVE TOWARD THE
AREA AND SHOULD AFFECT THE TERMINALS AFTER 18Z. GUIDANCE INDICATES
CIGS SHOULD REMAIN VFR IN THE 4000-5000 FT RANGE...THOUGH PATCHY
HIGH END MVFR CIGS MAY BRIEFLY OCCUR IN HEAVIER SHRA. SHOWERS WILL
END WITH THE FRONTAL PASSAGE THIS EVENING...WITH VFR CONDITIONS
EXPECTED OVERNIGHT.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 15Z...
* HIGH CONFIDENCE IN SOUTH WINDS GUSTING AOA 25 KTS TODAY.
* MEDIUM CONFIDENCE IN SHRA TIMING THIS AFTERNOON.
* MEDIUM CONFIDENCE IN PREVAILING CIGS REMAINING VFR.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT...
TUESDAY...VFR.
WEDNESDAY...CHC SHRA...MAINLY VFR.
THURSDAY...CHC SHRA...MVFR CIGS POSSIBLE.
FRIDAY...VFR.
SATURDAY...CHC SHRA.
RATZER
&&
.MARINE...
256 AM CDT
SOUTH-SOUTHEAST GALES ARE EXPECTED ON THE CENTRAL AND SOUTHERN
PORTIONS OF LAKE MICHIGAN TODAY.
LOW PRESSURE DEVELOPING ALONG THE IOWA-MINNESOTA BORDER EARLY THIS
MORNING WILL RESULT IN A TIGHTENING OF THE SURFACE PRESSURE
GRADIENT ACROSS LAKE MICHIGAN THIS MORNING...WITH WINDS QUICKLY
INCREASING TO GALE FORCE BY MID-MORNING. GALES IN THE 35-40 KT
RANGE WILL LIKELY LAST THROUGH THE AFTERNOON INTO THE EARLY
EVENING HOURS...BEFORE THE LOW MOVES INTO WISCONSIN AND BEGINS TO
FILL ALLOWING THE PRESSURE GRADIENT TO WEAKEN AND WINDS TO EASE
AND VEER TO THE SOUTHWEST. THE LOW WILL THEN CONTINUE TO WEAKEN TO
AN OPEN TROUGH AS IT LIFTS NORTH-NORTHEAST ACROSS THE NORTHERN
LAKES MONDAY.
STRONGER LOW PRESSURE FAR TO THE NORTH OVER CANADA WILL TRAIL A
COLD FRONTAL TROUGH THROUGH THE UPPER MIDWEST MONDAY NIGHT INTO
TUESDAY PRODUCING A PERIOD OF SOUTHWEST WINDS TROUGH MID-WEEK
BEFORE THE FRONT SLIPS SOUTHEAST ACROSS THE WESTERN LAKES.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 PM
SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 10 PM SUNDAY.
&&
$$
