NWS Area Forecast Discussion
FXUS63 KLOT 050308 AFDLOT AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 1008 PM CDT SAT SEP 4 2010 .DISCUSSION... 244 PM CDT UNSEASONABLY COOL TEMPERATURES AND BREEZY CONDITIONS OCCURRED TODAY AS A LOW PRESSURE SYSTEM DRIFTED SLOWLY EAST OVER WESTERN QUEBEC BUT DO EXPECT WARMER WEATHER CONDITIONS TO FINISH OUT THIS HOLIDAY WEEKEND. A TIGHT PRESSURE GRADIENT WILL CONTINUE TO RELAX OVER THE NEXT 24 HOURS AS A RIDGE OF HIGH PRESSURE BEGINS TO MOVE INTO THE UPPER MIDWEST. THIS WILL CAUSE WINDS TO WEAKEN AND EVENTUALLY SHIFT TO MORE SOUTHERLY ON SUNDAY AS THE RIDGE AXIS SHIFTS TO THE EAST OF THE FORECAST AREA. THIS WILL ALLOW WARMER AIR TO ENTER THE REGION...THUS CONTINUE TO CALL FOR AN 8-10F WARMING TREND EACH DAY FOR THE NEXT COUPLE DAYS. H85 TEMPS IN THE LOW SINGLE DIGITS TODAY WILL GRADUALLY WARM TO NEAR 20C BY MONDAY AFTERNOON AS A LOW PRESSURE SYSTEM DEVELOPS OVER THE NORTHERN PLAINS AND SOUTHWESTERLY FLOW INCREASES. A WEAK WARM FRONT PASSES THROUGH SUNDAY NIGHT INTO MONDAY MORNING...HOWEVER DUE TO THE ALIGNMENT OF THE RIDGE AXIS WHICH EXTENDS SOUTHWEST INTO LOUISIANA...MOISTURE AVAILABILITY WILL BE A LIMITING FACTOR FOR ANY WIDESPREAD PRECIPITATION. MODELS INDICATE A DRY FRONTAL PASSAGE AND PRECIP IS EXPECTED TO OCCUR FURTHER NORTH WHERE MORE FAVORABLE ISENTROPIC LIFT IS OCCURRING. AS THE LOW LIFTS NORTH INTO CANADA...A TRAILING COLD FRONT IS THEN EXPECTED TO PUSH THROUGH THE REGION TUESDAY. MODELS SOUNDINGS SHOW WEAK MID LEVEL LAPS RATES...AND ELEVATED WARM LAYER. IN ADDITION...WINDS BEHIND FRONT NEVER REALLY GAIN ANY NORTHERLY COMPONENT...AND WITH RIDGE AXIS SOUTH OF THE AREA STILL STRETCHING AS FAR WEST AS TEXAS...DONT SEE MUCH IN TERMS OF MOISTURE AVAILABILITY. ALL THINGS CONSIDERED...SYSTEM DOES NOT LOOK TERRIBLY IMPRESSIVE SO ONLY CALLING FOR SLIGHT CHANCE PRECIPITATION ALONG THE FRONT. AMPLIFIED UPPER RIDGE THEN BUILDS OVERHEAD FOR THE MIDDLE OF NEXT WEEK WITH THE NEXT SIGNIFICANT SYSTEM EXPECTED FRIDAY. BMD && .FIRE WEATHER... 330 AM CDT ON MONDAY...SOUTH WINDS ARE EXPECTED TO INCREASE INTO THE 15 TO 25 MPH RANGE WITH SOME GUSTS TO 30 MPH OR SLIGHTLY HIGHER. THERE IS A POSSIBILITY THAT SOME DRIER LOW LEVEL AIR MAY MIX DOWN TO THE SURFACE WHICH WOULD RESULT IN MINIMUM AFTERNOON RELATIVE HUMIDITIES AROUND OR LESS THAN 30 PERCENT. CONFIDENCE IN MEETING RED FLAG CONDITIONS IS LOW AT THIS POINT GIVEN UNCERTAINTY AS TO HOW MUCH OF THIS LOW LEVEL DRY AIR WILL MIX TO THE SURFACE...AND ALSO 10 HR FUEL MOISTURES ARE STILL RUNNING ON THE HIGH SIDE ACROSS THE AREA. MARSILI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 03Z... WINDS WILL REMAIN LGT FROM W/NW. WINDS BECOME SW BY 15Z THEN GUSTY SW WINDS TO 20KTS BY 18Z. BEACHLER //DISCUSSION...UPDATED 00Z... VERY DRY AIR MASS CONTINUES TO HOVER OVER THE GREAT LAKES REGION AND PROVIDE MINIMAL CLOUD COVER. HIGH PRESSURE WILL REMAIN CENTERED SOUTH OF NORTHERN IL/NORTHWEST IN...AND SLOWLY DRIFT EAST OVERNIGHT. SKIES WILL BECOME SKC BY 02-03Z AND REMAIN THRU DAYBREAK SUN. WINDS WILL RAPIDLY DECOUPLE BY 02Z WITH NW WINDS ARND 5-7KTS FOR MOST TERMINALS. THEN AS HIGH PRESSURE DRIFTS EAST OVERNIGHT WINDS WILL BACK TO SOUTHWESTERLY ARND 12-15Z...THEN GRADUALLY INCREASE. BY 18Z SW WINDS WILL GUST BTWN 15-20KTS THRU 00Z MON. THE ATMOS SHUD REMAIN RELATIVELY DRY...WITH MINIMAL MOISTURE ADVECTING INTO NORTHERN IL/NORTHWEST IN SUN AFTN CLOUDS SHUD REMAIN MINIMAL. SOME GUIDANCE MEMBERS ARE SUGGESTING LATE SUN ADDTL CLOUDS/MOISTURE WILL ADVECT NE TWRDS NORTHERN IL...HOWEVER THIS APPEARS TO BE MORE LIKELY AS CLOUDS. THUS PRECIP SHUD REMAIN OUT OF AIRFIELDS THRU AT LEAST 00Z MON. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 03Z... HIGH CONFIDENCE IN ALL FORECAST ELEMENTS. BEACHLER //OUTLOOK FOR ORD/MDW FOR 06Z MONDAY-12Z FRIDAY...UPDATED 18Z... SUNDAY NIGHT...VFR. MONDAY...VFR. CHC TSRA LATE. TUESDAY...VFR. CHC SHRA/ISO TSRA W/PATCHY MVFR. WEDNESDAY...VFR. CHC SHRA/ISO TSRA EARLY. THURSDAY...VFR. CHC SHRA/ISO TSRA. FRIDAY...VFR. CHC TSRA. && .MARINE... 151 PM CDT THE LOW IN NORTHWEST QUEBEC WILL REMAIN IN NORTHWEST QUEBEC THROUGH SUNDAY MORNING. THEN THE LOW MAY MOVE TO JUST WEST OF JAMES BAY AFTER MIDNIGHT SUNDAY NIGHT. THE WIND WILL BE NORTHWEST UNTIL VERY EARLY SUNDAY MORNING. A STRONG LOW WILL DEVELOP IN WESTERN NEBRASKA SUNDAY AFTERNOON. THIS LOW WILL CAUSE THE WIND TO BECOME SOUTH OVER LAKE MICHIGAN SUNDAY. THE SOUTHERN HALF OF THE LAKE WILL HAVE A SOUTH WIND BY SUNDAY AFTERNOON AND THE NORTHERN HALF WILL HAVE A SOUTH WIND BY SUNDAY EVENING. THE WIND SPEED WILL BE 10 TO 15 KNOTS. THE WAVES WILL NOT BE AS LARGE AS THEY WERE THIS SATURDAY MORNING. && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 AM SUNDAY. && $$ |
| contact | disclaimer |
© 2006-2010 Lake County SKYWARN
Design & Hosting by Greg Perkins
