000
FXUS63 KLOT 182341
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
641 PM CDT THU MAR 18 2010
.DISCUSSION...
319 PM CDT
DAY 1-3 DISCUSSION: HAVE GENERALLY GONE WITH GFS SCENARIO HEADING
THROUGH THE UPCOMING WEEKEND PERIOD. STILL LOTS OF INCONSISTENCIES
AMONG MODELS REGARDING WEEKEND STORM SYSTEM AND WITH CURRENT WATER
VAPOR IMAGERY SUPPORTING GFS THROUGH INITIAL FCST PERIOD SEE NO
REASON TO DEVIATE MUCH FROM INHERITED FCST.
OUT THE GATE...THROUGH NEAR TERM...VIS SATELLITE IMAGERY SHOWS
BAND OF ACCAS AND VIRGA NOW CROSSING FA. THIS IS IN RESPONSE TO
ZONE OF STRONGER WARM ADVECTION NOW RUNNING FROM NERN KS TO SRN LK
MI. THIS WILL PASS OFF TO SE THIS EVENING LEAVING AREA GENERALLY
CLR. WITH ELEVATED WINDS WELL INTO THIS EVENING...EXPECT TEMPS TO
BE MILDER THAN LAST NIGHT...WITH 12Z MOS NUMBERS LOOKING GOOD.
ON FRIDAY...WILL GO WITH INCREASING CLOUDINESS AS SYSTEM TO W
APPROACHES AND SHALLOW SLOPED FRONT SAGS SEWD ACROSS FA DURING THE
AFTERNOON HRS. FRONTAL MOVEMENT WILL REMAIN FAIRLY SLOW AS NRN
SHORT WAVE NOW PUNCHING ACROSS SRN CANADA SHIFTS EWD INTO WRN
ONTARIO BY FRIDAY NIGHT. STRONGER PRESSURE RISES AND COLD
ADVECTION WITH THIS WAVE NOW PUNCHING SWD ACROSS SRN SASKATCHEWAN
AND SWRN MANITOBA. THIS PUSH OF COLD AIR WILL RELAX AND BE SHUNTED
EWD WELL TO N OF FA AS ANOTHER WAVE...NOW SHOWING UP OVER SRN
ALBERTA...DIGS SWD AND AMPLIFIES CONSIDERABLY OVER CNTRL ROCKIES.
THIS WILL BACK MID LVL WIND FLOW ACROSS PLAINS AND MIDWEST
RESULTING IN SLOW MOVEMENT TO SHALLOW SLOPED FRONT. SO...THOUGH
TEMPERATURE DROP FRIDAY NIGHT INTO SATURDAY MAY BE A BIT OF A
SHOCK...EXPECT FORM OF PRECIP TO TAKE QUITE A WHILE TO TRANSITION
FROM RAIN TO SNOW. SET UP FAVORS LOW CLOUDS AND PRECIP TO BE POST
FRONTAL SO AGAIN...MOST OR FRIDAY LOOKS PRETTY GOOD BEFORE THINGS
GO DOWNHILL FRIDAY NIGHT AND SATURDAY. STRONG CYCLONE DVLPMRT IS
NOW FCST TO TAKE PLACE FURTHER TO S AND E THAN IN PREVIOUS
RUNS...WITH THIS TREND ALSO ADVERTISED ON EURO AND NAM.
THEREFORE...WILL TAPER OFF POPS/PRECIP MENTION SATURDAY
NIGHT...WITH ONLY CHC MENTION MOST AREAS BY SUNDAY MORNING.
MERZLOCK
DAYS 4-7 DISCUSSION: FOR MONDAY THROUGH THURSDAY...GFS AND ECMWF HAVE
THE UPPER LOW OVER THE OHIO VALLEY BEGINNING TO PULL
AWAY...EVENTUALLY REACHING THE ATLANTIC COAST BY TUESDAY MORNING.
ANY LINGERING LIGHT RAIN ON THE BACK SIDE OF THIS SYSTEM SHOULD BE
OUT OF OUR SOUTHEASTERN COUNTIES BY MONDAY AFTERNOON. HIGH
TEMPERATURES RECOVER AT LEAST INTO THE 50S BY MIDWEEK UNDER WEAK
RIDGING AT UPPER LEVELS. THIS GETS INTERRUPTED ON WEDNESDAY BY A
SHORTWAVE MOVING ACROSS THE NORTHERN MIDWEST. THE BEST CHANCE OF
RAIN APPEARS TO REMAIN NORTH OF THE AREA...ALTHOUGH A COLD FRONT
MOVING THROUGH ON WEDNESDAY MAY COOL THINGS OFF A FEW DEGREES BY
THURSDAY.
LENNING
&&
.AVIATION...
0000 UTC TAFS...
THE PRIMARY AVIATION CONCERN THIS AFTERNOON HAS BEEN THE GUSTY
WINDS...BUT WITH THE SETTING SUN...GUSTS ARE SETTLING DOWN.
SO...WILL START OUT THE 00Z UPDATE WITH NO GUSTS IN THE INITIAL
PORTION OF THE FORECAST...BUT WITH A MODEST GRADIENT BETWEEN LOW
PRESSURE TO THE NORTH AND HIGH PRESSURE TO THE SOUTH...WINDS
SHOULD REMAIN WESTERLY AROUND 10KT THROUGH THE NIGHT. CIGS/VIS
WILL REMAIN UNRESTRICTED THROUGH THE NIGHT AS WELL...WITH THE ONLY
CHANGE IN CLOUD COVER BEING INCREASING CI AHEAD OF THE DEVELOPING
UPPER TROUGH TO THE WEST.
THE MAIN CONCERN FOR TOMORROW WILL BE A COLD FRONT APPROACHING
FROM THE UPPER MISSISSIPPI VALLEY IN THE AFTERNOON. EXPECT A WIND
SHIFT FROM SWLY TO NWLY DURG THE AFTERNOON HOURS. EXPECT
INCREASING CLOUD COVER AS WELL WITH THE THICKER CLOUD GENERALLY
POST-FRONTAL. CIGS SHOULD REMAIN VFR THROUGH THE 24 HOUR
PERIOD...THOUGH ANTICIPATE CIGS LOWERING TO MVFR FOR THE 30-HR
EXTENDED PERIOD AT ORD AS WINDS CONTINUE TO VEER MORE NELY.
KREIN
&&
.MARINE...
242 PM CDT
MAIN CONCERN FOR MARINE FORECAST CONTINUES TO BE ON POTENTIAL FOR
PERIOD OF GUSTY NORTH WINDS LATE FRIDAY AND SATURDAY.
LOW PRESSURE OVER WESTERN ONTARIO WILL MOVE NORTH OF THE LAKES
TONIGHT AND WILL TRAIL A COLD FRONT DOWN LAKE MICHIGAN THROUGH
FRIDAY. COLD AIR BEHIND THE FRONT WILL DECREASE STABILITY OVER THE
WATER...WHILE THE PRESSURE GRADIENT TIGHTENS IN RESPONSE TO HIGH
PRESSURE BUILDING SOUTH ACROSS THE HIGH PLAINS. MODEL FORECAST
SOUNDINGS CONTINUE TO INDICATE WINDS INCREASING TO 30 KTS LATE
FRIDAY NIGHT/EARLY SATURDAY...BEFORE WEAKER EASTWARD EXTENSION OF
HIGH PRESSURE RIDGE SETTLES OVER THE LAKES SATURDAY AND SATURDAY
NIGHT. PERIOD OF GUSTY NORTH WINDS AND LONG FETCH WILL LIKELY
RESULT IN SMALL CRAFT ADVISORY CONDITIONS FOR ILLINOIS AND INDIANA
NEARSHORE WATERS FRIDAY NIGHT...WITH WAVES MAINTAINING HAZARDOUS
CONDITIONS INTO SUNDAY AFTERNOON DUE TO LONG PERIOD OF NORTHERLY
FETCH DESPITE DECREASING WINDS.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
