FXUS64 KMEG 091223
AFDMEG
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
623 AM CST WED DEC 9 2009
.UPDATE...12Z SURFACE PLOT CENTERS 978 MB LOW PRESSURE ACROSS
NORTHERN ILLINOIS WITH AN ARCTIC COLD FRONT LOCATED ACROSS CENTRAL
ARKANSAS. BASED ON LATEST SHORT TERM TRENDS AND PRESSURE
GRADIENT...DECIDED TO ISSUE A WIND ADVISORY FOR NORTHEAST
ARKANSAS...THE MISSOURI BOOTHEEL AND WEST TENNESSEE THROUGH NOON
TODAY AS SUSTAINED WEST WINDS BETWEEN 25 TO 30 MPH WITH GUSTS TO
40 MPH ARE EXPECTED.
UPDATED GRIDS ALREADY SENT.
CJC
&&
.PREV DISCUSSION... /ISSUED 555 AM CST WED DEC 9 2009/
UPDATE...
UPDATED FOR AVIATION.
PREV DISCUSSION... /ISSUED 513 AM CST WED DEC 9 2009/
DISCUSSION...10Z SURFACE ANALYSIS PLACES A 980 MB LOW OVER
NORTHERN ILLINOIS/SOUTHERN LAKE MICHIGAN WITH A TRAILING COLD
FRONT EXTENDING SOUTH INTO EAST TENNESSEE AND ALABAMA. ACROSS THE
MID SOUTH THIS MORNING SKIES ARE MOSTLY CLEAR ACROSS NORTH
MISSISSIPPI AND PARTLY TO MOSTLY CLOUDY SKIES ACROSS NORTHEAST
ARKANSAS AND THE MISSOURI BOOTHEEL AS OF FORECAST ISSUANCE. AS OF
4 AM CST...TEMPERATURES ACROSS THE FORECAST AREA RANGE FROM THE
MID 40S ACROSS EAST ARKANSAS AND THE MISSOURI BOOTHEEL AND LOWER
TO MIDDLE 50S ACROSS NORTHEAST MISSISSIPPI. MAIN CHALLENGE IN
THIS MORNING/S FORECAST PACKAGE IS WIND ADVISORY POTENTIAL.
SHORT TERM...(TODAY THROUGH FRIDAY)...A STRONG AREA OF LOW
PRESSURE CURRENTLY LOCATED ACROSS NORTHERN ILLINOIS WILL MOVE
ACROSS LOWER MICHIGAN TODAY AND INTO EASTERN ONTARIO/WESTERN
QUEBEC BY TONIGHT. A STRONG PRESSURE GRADIENT ASSOCIATED WITH THE
LOW IS PRODUCING WIND GUSTS TO AROUND 30 KTS ACROSS THE LOWER
MISSISSIPPI VALLEY...ESPECIALLY TOWARDS THE MISSOURI/KENTUCKY
BORDER. SHORT TERM MODEL SOUNDINGS INDICATE BOUNDARY LAYER WINDS
WILL REMAIN AROUND 40 KTS THIS MORNING. HOWEVER...DECIDED NOT TO
ISSUE A WIND ADVISORY AT THIS TIME AS SUSTAINED WINDS OVERNIGHT
HAVE NOT BEEN ABLE TO SATISFY WIND ADVISORY CRITERIA.
NONETHELESS...WILL CONTINUE TO MONITOR SHORT TERM TRENDS
ESPECIALLY NORTH OF I-40 THIS MORNING.
MEANWHILE...INFRARED SATELLITE TRENDS THIS MORNING SHOW CLOUD COVER
ON THE BACK SIDE OF THE LOW SPREADING ACROSS NORTH CENTRAL
ARKANSAS. THIS WILL PRODUCE PARTLY SUNNY SKIES NORTH OF I-40 THIS
MORNING WITH SUNNY SKIES FOR THE AFTERNOON. HIGH TEMPERATURES
WILL OCCUR AROUND SUNRISE WITH TEMPERATURES GRADUALLY FALLING
THROUGHOUT THE DAY AS COLD ARCTIC HIGH PRESSURE SETTLES INTO THE
MISSISSIPPI VALLEY. TEMPERATURES TONIGHT AND THURSDAY NIGHT WILL
FALL BACK INTO THE 20S AT MOST LOCATIONS WITH HIGHS THURSDAY
RANGING FROM THE MIDDLE TO UPPER 30S NORTH TO LOWER 40S ACROSS
NORTH MISSISSIPPI.
00Z WRF/GFS SHORT TERM MODELS IN ADDITION TO THE 00Z ECMWF
INDICATE HIGH PRESSURE WILL GRADUALLY MOVE EAST FRIDAY AS AN AREA
OF LOW PRESSURE MOVES ACROSS THE NORTHERN GULF OF MEXICO.
CONFIDENCE IN MOISTURE RETURN DURING THE DAY FRIDAY IS LOW DUE TO
MODELS HAVING DIFFICULTY RESOLVING THE TRANSITION FROM ZONAL FLOW
TO SOUTHWEST FLOW ALOFT. AS A RESULT...DECIDED TO REMOVE POPS DURING
THE DAY FRIDAY AS BEST MOISTURE IS ANTICIPATED TO REMAIN SOUTH OF
THE FORECAST AREA.
LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)...00Z GFS/ECMWF LONG
RANGE MODELS INDICATE OVERRUNNING PRECIPITATION ASSOCIATED WITH
SURFACE LOW MOVING ALONG THE GULF COAST WILL SPREAD NORTH BUT REMAIN
PREDOMINANTLY ACROSS NORTH MISSISSIPPI FRIDAY NIGHT AS
TEMPERATURES FALL BACK INTO THE UPPER 20S TO MIDDLE 30S ACROSS THE
MID SOUTH. MODEL SOUNDINGS INDICATE PRECIPITATION WILL REMAIN AS
RAIN ACROSS NORTH MISSISSIPPI AND CONFIDENCE FOR WINTER
PRECIPITATION FRIDAY NIGHT IS LOW BASED ON LATEST MODEL GUIDANCE.
LATER SHIFTS WILL CONTINUE TO ASSESS WINTER WEATHER POTENTIAL AS
ADDITIONAL MODEL DATA ARRIVES. STAY TUNED...
MODELS INDICATE RAIN WILL SPREAD ACROSS THE REMAINDER OF THE MID
SOUTH ON SATURDAY THEN ENDING BY SUNDAY. ANOTHER COLD FRONT WILL
MOVE THROUGH THE AREA MONDAY NIGHT INTO TUESDAY...BRINGING AN
ADDITIONAL CHANCE OF RAIN TO THE AREA. KEPT POPS IN THE LONG TERM
ON THE LOW END DUE TO THE LARGE MODEL SOLUTION VARIABILITY FROM
RUN TO RUN.
CJC
&&
.AVIATION...
12Z TAFS
PRIMARY AVIATION CONCERN REMAINS WINDS...IN THE WAKE OF A DEEP
979MB SURFACE LOW NEAR KORD. THIS LOW WILL PULL NORTHEAST ACROSS
THE GREAT LAKES THROUGH THE DAY... RESULTING IN GRADUALLY DECREASING
SURFACE WINDS ACROSS THE MIDSOUTH.
11Z SURFACE MAP AND GOES MULTICHANNEL IR IMAGERY SHOWED A PRESSURE
TROF/COLD FRONTAL BOUNDARY HAD MOVED THROUGH KMEM/KMKL. SAW JUST
ENOUGH OF A PRESSURE SURGE TO BUMP WINDS UP RATHER SIGNIFICANTLY.
LATEST METARS HAVE SETTLED DOWN SOME...BUT EXPECT POST SUNRISE
MIXING TO ONCE AGAIN INCREASE WINDS INTO THE 20G30KT RANGE. POST
FRONTAL MVFR CIGS SHOULD PASS OFF TO THE SOUTHEAST OF KMEM BY 12Z...
OR SHORTLY THEREAFTER.
NAM MODEL SUGGEST MVFR CIGS OVER MO TO GRADUALLY BREAK UP AS THEY
APPROACH THE MIDSOUTH THROUGH 18Z. HAVE KEPT A BRIEF TEMPO FOR
BROKEN MVFR...BUT ABOVE THE FL020 FUEL ALTERNATE LEVEL.
PWB
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 44 23 43 24 / 0 0 0 0
MKL 45 21 38 19 / 0 0 0 0
JBR 42 21 38 21 / 0 0 0 0
TUP 50 25 44 24 / 0 0 0 0
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...WIND ADVISORY UNTIL NOON CST TODAY FOR CLAY-CRAIGHEAD-CRITTENDEN-
CROSS-GREENE-LAWRENCE-MISSISSIPPI-POINSETT-RANDOLPH-ST.
FRANCIS.
MO...WIND ADVISORY UNTIL NOON CST TODAY FOR DUNKLIN-PEMISCOT.
MS...NONE.
TN...WIND ADVISORY UNTIL NOON CST TODAY FOR CARROLL-CHESTER-CROCKETT-
DECATUR-DYER-FAYETTE-GIBSON-HARDEMAN-HARDIN-HAYWOOD-
HENDERSON-HENRY-LAKE-LAUDERDALE-MADISON-MCNAIRY-OBION-
SHELBY-TIPTON-WEAKLEY.
&&
$$
