Area Forecast Discussion
Issued by NWS La Crosse, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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 241922
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
222 PM CDT FRI APR 24 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 222 PM CDT FRI APR 24 2015

AS WAVE EJECTS OUT OF SOUTHWEST U.S. MAIN FOCUS IN SHORT TERM IS
RAIN THREAT...ESPECIALLY ON SATURDAY AS SYNOPTIC SURFACE LOW PASSES
BY TO THE SOUTH.

WEAKER INITIAL SHORT WAVE TROUGH SWINGING THROUGH AREA THIS
AFTERNOON HAS GENERATED BROAD RAIN SHIELD WITH SOME WARM AIR
ADVECTION. CONSIDERABLY DRIER AIR IN CENTRAL AND EASTERN WISCONSIN
WILL BATTLE THIS. AS FORCING SHIFTS EAST THIS EVENING...BULK OF RAIN
SHOULD END BY EARLY EVENING WITH ONLY PATCHY THREAT AFTER THAT. THIS
TREND IS SUPPORTED IN HIGH RESOLUTION MODELS AND HAVE ADJUSTED RAIN
CHANCES DOWNWARD TO ACCOUNT FOR THAT.

AS STRONGER MAIN WAVE EJECTS INTO CENTRAL U.S. TONIGHT...WITH
STRONGER...DEEPER Q-G FORCING...EXTENSIVE AREA OF RAIN AND
THUNDERSTORMS WILL FORM ACROSS PARTS OF THE CORNBELT AND MID
MISSISSIPPI RIVER VALLEY. BETTER AGREEMENT IN 24.12Z MODELS WITH HOW
FAR NORTH PRECIPITATION WILL GET WHILE SOME MODELS HAVE BEEN VERY
CONSISTENT KEEPING RAIN SOUTH OF INTERSTATE 90 CONSISTENTLY. THIS
WILL MEAN A TIGHT NORTH-SOUTH GRADIENT IN RAIN CHANCES MAINLY
SATURDAY MORNING BEFORE SYSTEM EXITS BY LATE AFTERNOON. AS SURFACE
LOW SHIFTS EAST...COULD ALSO SEE INCREASING EAST TO NORTHEAST WINDS
PICK UP DRIER AIR TO THE NORTHEAST WHICH WOULD ALSO BATTLE NORTHWARD
EXTENT OF PRECIPITATION.

HAVE TRIED TO TIGHTEN THIS RAIN THREAT GRADIENT UP WITH UP TO AN
INCH OF RAIN POSSIBLE CLOSER TO HIGHWAY 20 IN IOWA...TO NOTHING
NORTH OF INTERSTATE 90. NIL TO MINIMAL CAPE SUGGEST THUNDER THREAT
TOO LOW TO MENTION THIS FAR NORTH.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 222 PM CDT FRI APR 24 2015

SHORT TERM UPPER RIDGE WILL BUILD IN QUICKLY SATURDAY NIGHT AS RAIN
THREAT ENDS AND SKIES CLEAR OUT. THIS WILL LAST INTO EARLY NEXT WEEK
WITH QUIET WEATHER ON TAP AND WARMING TEMPERATURES...CLOSER TO
NORMALS FOR LATE APRIL.

UPPER FLOW ACROSS U.S. BECOMES FAR MORE MESSY NEXT WEEK WITH LARGE
LOW OFF OF NORTHEAST AND SPLIT FLOW DEVELOPS IN WEST. THIS COULD
LEAVE OUR REGION IN FAIRLY QUIET PATTERN BETWEEN ALL THIS. MEDIUM
RANGE GUIDANCE SUGGESTS WEAK WAVE COULD DRAG COLD FRONT INTO AREA
NEXT TUESDAY WITH MINOR RAIN THREAT BUT BESIDES THAT...MORE SIGNALS
FOR RIDGING AND NICE SPRING WEATHER.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1259 PM CDT FRI APR 24 2015

INITIAL ROUND OF SHOWERS MOVING ACROSS THE AREA IN A REGION OF
SOME ISENTROPIC UP GLIDE AND FRONTOGENESIS IN THE 1000-700 MB
LAYER. THESE HAVE BEEN ABLE TO PRODUCE SOME SHORT PERIODS OF MVFR
CONDITIONS. LOOKING AT THE 24.15Z HRRR AND 24.18Z NAM...THESE
SHOWERS WILL CONTINUE TO PROGRESS NORTHEAST BUT WILL HAVE A TOUGH
TIME GETTING VERY FAR INTO WESTERN WISCONSIN WHERE DEW POINTS
HAVE REMAINED IN THE TEENS. PLAN TO SHOW TEMPO GROUPS FOR BOTH TAF
SITES THROUGH THE MIDDLE OF THE AFTERNOON WITH THE SHOWERS AROUND
AND THE POTENTIAL FOR MVFR CONDITIONS. AFTER THAT...THE FORCING
BEGINS TO REFOCUS FARTHER TO THE SOUTH WITH THE FRONTOGENESIS
FOCUSING OVER EXTREME SOUTHERN WISCONSIN INTO IOWA AS THE MAIN
SURFACE LOW TRACKS ACROSS KANSAS INTO MISSOURI. THIS SHOULD TAKE
MOST OF THE RAIN SOUTH OF BOTH TAF SITES AND WENT BACK TO JUST
VCSH FOR THE LATE AFTERNOON INTO THE EARLY EVENING. AFTER
THAT...THINK THE ACTIVITY WILL BE TO THE SOUTH AND HAVE GONE DRY
FOR THE REMAINDER OF THE PERIOD. WITH THE LOW LEVEL FLOW TURNING
MORE TO THE EAST...THIS WILL HELP TO BRING IN THE LOW LEVEL DRY
AIR WHICH SHOULD SERVE TO KEEP CEILINGS VFR ONCE THE SHOWERS ARE
OUT OF THE AREA.

&&

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

$$

SHORT TERM...SHEA
LONG TERM...SHEA
AVIATION...04



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