Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 200451
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1151 PM CDT SUN APR 19 2015

.SHORT TERM...(TONIGHT THROUGH TUESDAY NIGHT)
ISSUED AT 245 PM CDT SUN APR 19 2015

SCATTERED SHOWERS RANGE FROM NORTHERN WI INTO NORTHEAST IA...WITH
LARGER AREA OF SHOWERS AND A FEW STORMS OVER SOUTHWEST IA.
ANOTHER AREA OF RAIN WAS MOVING NORTH ACROSS CENTRAL ILL.

COLD FRONT TRACKING EAST ACROSS THE REGION TONIGHT...WITH GOOD
FRONTOGENETIC FORCING ASSOCIATED WITH IT. QG FORCING INCREASES IN
THE 850-500 MB LAYER THIS EVENING...ALONG THE FRONT AND JUST AHEAD
OF AN APPROACHING UPPER LEVEL TROUGH. TO THE SOUTH...A SHORT WAVE
TROUGH/SFC LOW ARE GOING TO STAY SOUTH...SLIDING ACROSS IL INTO
MICH. TRACK WILL SERVE TO BRING SOME MOISTURE NORTHWARD INTO WI
THOUGH...HELPING TO FUEL SHOWER CHANCES. ALL THE FORCING SHOULD
RESULT IN A BLOSSOMING AREA OF PCPN THIS EVENING...WITH MODEL
CONSENSUS FAVORING MISSISSIPPI RIVER-WEST THIS EVENING...GRADUALLY
EASING EAST OVERNIGHT. THE RAIN WILL THEN CONTINUE TO LIFT EAST
NORTHEAST THROUGH THE REST OF MON MORNING.

CYCLONIC FLOW A LOFT AND COLD AIR ADVECTION MON/TUE SETS THE STAGE
FOR SOME SHOWER POTENTIAL. GOOD LOW/MID LEVEL LAPSE RATES ALONG WITH
A 100-200 MB LAYER OF WEAK INSTABILITY ABOVE 800 MB MON/TUE
AFTERNOONS...PER BUFKIT SOUNDINGS. BITS OF UPPER LEVEL ENERGY
PROGGED TO SPIRAL AROUND THE 500 MB LOW...WITH MODEL CONSENSUS ON
DRIVING A PIECE ACROSS THE FORECAST AREA TUE AFTERNOON. RH FIELDS
KEEP THE DEEPEST SATURATION ACROSS THE NORTH...BUT ENOUGH SHOULD BE
AROUND TO FUEL THE INSTABILITY SHOWER THREAT. TUE LOOKING LIKE
THE HIGHER PROBABILITY DAY WITH THE ADDITION OF THE RIPPLE IN THE
UPPER LEVEL FLOW.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 245 PM CDT SUN APR 19 2015

MODELS IN GOOD AGREEMENT WITH A PATTERN SHIFT FOR THE UPCOMING WEEK.
THE UPPER LEVEL TROUGH WILL HOLD FAST ACROSS SOUTHEAST CANADA...WITH
THE RESULTING NORTHWEST FLOW PROVIDING A CONTINUOUS FETCH OF
UNSEASONABLY COLD AIR. 850 MB TEMPS FALL FROM AROUND 8 C TODAY...TO
-8 C BY TUE. EXPECTING HIGHS 10 TO 15 DEGREES BELOW NORMAL INTO NEXT
WEEKEND. ASIDE FROM THE START OF THE NEW WORK WEEK...THE PATTERN
FAVORS DRY CONDITIONS FOR THE LOCAL AREA.

MODELS START TO STRAY FROM EACH OTHER TOWARD FRIDAY WITH THE EC/GEM
FAVORING SOME UPPER LEVEL RIDGE BUILDING WHILE THE GFS PREFERS TO
HOLD ONTO THE TROUGH TROUGH THE WEEKEND. OBVIOUS IMPACTS ON TEMPS
//COOL WOULD CONTINUE WITH GFS - RETURN TO NORMAL WITH GEM/EC // BUT
SCENARIOS STILL LEAN ON THE DRY SIDE. NOT SOLD WE/LL BREAK OUT OF
THE COOL PATTERN...BUT GOING TO LEAN ON THE CONSENSUS SOLUTION FOR
THE DETAILS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1151 PM CDT SUN APR 19 2015

LOW PRESSURE WILL DEEPEN AND LIFT NORTH FROM SOUTHERN LAKE
MICHIGAN INTO SOUTHERN ONTARIO BY MONDAY AFTERNOON. THIS LOW WILL
CONTINUE TO PRODUCE SHRA ACROSS THE AREA...EVENTUALLY ENDING AT
KRST BY 11Z AND AT KLSE AROUND 12Z. PLAN ON MVFR CLOUD
OVERNIGHT...EVENTUALLY LIFTING INTO VFR CATEGORY AT KRST BY 17Z
AND AROUND 20Z AT KLSE. OTHERWISE...GUSTY NORTHWEST WINDS WILL BE
SEEN OVERNIGHT THROUGH MONDAY WITH GUSTS IN THE 30-35KT RANGE.
LOOK FOR THESE WINDS TO SUBSIDE MONDAY EVENING. WILL BE WATCHING A
MID-LEVEL TROUGH RIPPLE THROUGH THE CYCLONIC FLOW ALOFT. THIS MAY
PRODUCE ISOLATED -SHRA LATE IN THE AFTERNOON INTO THE EVENING
HOURS...BUT NOT CONFIDENT ENOUGH AT THIS POINT TO INCLUDE IN THE
TAFS.

&&

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

$$

SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION...DAS



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