Area Forecast Discussion
Issued by NWS La Crosse, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KARX 271137
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
637 AM CDT MON JUL 27 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CDT MON JUL 27 2015

AT 3 AM...A WARM FRONT WAS LOCATED OVER NORTHERN MISSOURI AND
NORTHWEST KANSAS. SOUTH OF THIS FRONT...SURFACE DEW POINTS WERE IN
THE MID AND UPPER 70S. MEANWHILE NORTH OF THIS FRONT...DEW POINT
RANGED MID 50S IN CENTRAL WISCONSIN TO THE LOWER 70S ACROSS SOUTH
CENTRAL AND SOUTHWEST MINNESOTA AND IOWA. IN ADDITIONAL
PRECIPITABLE WATER RANGED FROM 1.50 TO 2.00 INCHES. INFRARED
SATELLITE AND RADAR DATA...SHOW A MESOSCALE CONVECTIVE COMPLEX WAS
LOCATED ACROSS KANSAS AND EASTERN NEBRASKA. THIS WAS DEVELOPING
NORTH OF THE WARM FRONT AND ON THE NOSE OF MODERATE TO STRONG 850
MB MOISTURE TRANSPORT.

FOR TODAY AND TONIGHT...THE MODELS ARE SHOWING THAT THE SURFACE
WARM FRONT WILL REMAIN WELL SOUTH OF THE AREA TODAY...AND THEN
MOVE NORTHWARD THROUGH THE AREA LATE TONIGHT AND TUESDAY MORNING.
WHILE THE 0-1 KM CAPES CLIMB UP INTO THE 1000 TO 1500 J/KG RANGE
TODAY AND THIS EVENING...THERE IS NO MOISTURE CONVERGENCE TO
GENERATE SHOWERS AND STORMS. THIS IS SUPPORTED IN THE MESO
MODELS...SO WENT DRY FOR THE AREA THROUGH MIDNIGHT TONIGHT.

DURING THE OVERNIGHT...THE 850 MB MOISTURE TRANSPORT BECOMES
MODERATE ACROSS SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND NORTH
CENTRAL WISCONSIN. AS THIS OCCURS...EXPECT THE MESOSCALE
CONVECTIVE COMPLEX THAT IS EXPECTED TO DEVELOP OVER WESTERN IOWA
AND SOUTHWEST MINNESOTA DURING THE EVENING TO MOVE TOWARD TO MOVE
INTO THE WESTERN AND NORTHERN PORTIONS OF THE FORECAST AREA. WITH
PRECIPITABLE WATER VALUES AROUND 1.8 INCHES AND WARM CLOUD DEPTHS
OF 4 TO 4.5 KM...EXPECT THAT ANY SHOWERS AND STORMS WILL BE
EFFICIENT RAIN MAKERS. MEANWHILE WITH THE 0-3 KM AND 0-6 KM SHEAR
WEAK...NOT ANTICIPATING ANY SEVERE WEATHER WITH THIS COMPLEX IN
OUR AREA.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 343 AM CDT MON JUL 27 2015

ON TUESDAY AND TUESDAY NIGHT...THE 27.00Z GFS HAD PROBLEMS WITH
CONVECTIVE FEEDBACK. THIS RESULT IN A VERY DEEP 925 AND 850 MB LOW
DEVELOPING OVER NORTH DAKOTA AND SOUTHERN MANITOBA. THIS RESULTED
IN THE WINDS AT THESE LEVELS BEING WAY TOO STRONG. THE GFS WINDS
ARE 10 TO 15 KNOTS STRONGER THAN EITHER THE NAM AND ECMWF IN OUR
AREA. THERE ARE EVEN STRONGER DIFFERENCE ACROSS NORTHERN MINNESOTA
AND THE EASTERN DAKOTAS. IN THESE AREAS...THE GFS WINDS ARE 15 TO
25 KNOTS STRONGER THAN THE NAM OR ECMWF. DUE TO THIS...LEFT THE
GFS OUT OF THE MIX.

MODERATE TO STRONG 850 MB MOISTURE TRANSPORT IS LOCATED IN THE
VICINITY OF THE COLD FRONT ON TUESDAY AND TUESDAY NIGHT. THE WARM
CLOUD LAYER DEPTHS DROP IN THE 3.5 TO 4 KM RANGE DURING THE
MORNING AND THEN CLIMB INTO THE 4 TO 4.5 KM RANGE DURING THE
AFTERNOON AND EVENING. PRECIPITABLE WATER VALUES VALUES CLIMB
FROM 1.5 TO 2 INCHES IN THE MORNING TO 2 TO 2.4 INCHES DURING THE
AFTERNOON AND EVENING. IF THESE PERCEPTIBLE WATER VALUES ARE
REALIZED...IT WOULD BE A RECORD FOR KMPX. THE RECORD IS 1.84 FOR
JULY 28TH AND 1.92 INCHES ON JULY 29TH. DUE TO ALL OF THIS
EXPECT...THAT ANY SHOWERS AND STORMS WILL BE VERY EFFICIENT RAIN
MAKERS.

LIKE THE PAST COUPLE OF DAYS...THE BEST SHEAR IS LOCATED IN THE
0-3 KM LAYER. WITH IT BEING OVER 30 KNOTS...EXPECT STORMS TO TAKE
ON A MORE LINEAR STRUCTURE ONCE THEIR COLD POOL HAS DEVELOPED. ONE
MAIN QUESTION IS WHETHER THE MORNING CONVECTION WILL LIMIT THE
SURFACE HEATING DURING THE AFTERNOON AND EVENING. THE STORM
PREDICTION CENTER HAS THE AREA UNDER A SLIGHT RISK....BUT IT IS
HIGHLY DEPENDENT UPON WHETHER THE INSTABILITY CAN REDEVELOP OR
NOT.

WITH CLOUDS AND PRECIPITATION ACROSS THE AREA...LOWERED THE
TUESDAY HIGH TEMPERATURES BY A FEW MORE DEGREES.

AFTER THIS SYSTEM...THE MODELS SHOW THAT A COLD FRONT WILL PROVIDE
A CHANCE OF SHOWERS AND THUNDERSTORMS ON THURSDAY NIGHT AND
FRIDAY. AT THIS TIME...THE INSTABILITY LOOKS TO BE LESS THAN
1000 J/KG. IF STORMS DEVELOP...THE 0-3 KM SHEAR WOULD FAVOR A
LINE OR LINES. BEYOND THIS TIME PERIOD...THE MODEL TIMING
CONTINUES TO BE VARIABLE...SO JUST LEFT THE MODEL BLEND ALONE FOR
NOW.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 637 AM CDT MON JUL 27 2015

AFTER SOME EARLY MORNING MIST AT KRST WITH MVFR VISIBILITY...VFR
CONDITIONS WILL QUICKLY RETURN NO LATER THAN 27.14Z. SHALLOW VALLEY
FOG FROM TRIBUTARIES IS ALSO SPILLING INTO THE MAIN MISSISSIPPI
RIVER CHANNEL...BUT NOT EXPECTED TO IMPACT KLSE RUNWAY BEFORE
BURNING OFF. FOR THE REST OF THE PERIOD EXPECT VFR CONDITIONS WITH
SOME CUMULUS IN THE 3500 TO 4000 FT AGL LAYER LATER THIS MORNING
AND THROUGH THE AFTERNOON. MAY NEED TO WATCH CEILINGS LATE IN THE
PERIOD/TUESDAY MORNING AS OVERNIGHT CONVECTION IS EXPECTED MAINLY
ACROSS CENTRAL MN AND MVFR CONDITIONS MAY SNEAK FAR ENOUGH EAST TO
IMPACT KRST BEFORE 28.12Z. FOR NOW...WILL KEEP VFR CONDITIONS IN
PLACE...BUT HINT AT POSSIBLE LOWER CEILINGS STARTING AT 28.10Z.
LIGHT SOUTHEAST WINDS WILL PERSIST THROUGH THE PERIOD.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...ROGERS


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.