Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 290804
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
255 AM CDT FRI MAY 29 2015

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 255 AM CDT FRI MAY 29 2015

AREA OF LIGHT SHOWERS EXPECTED TO BECOME A LITTLE MORE WIDESPREAD AS
IT ADVANCES NORTHEAST ACROSS THE REGION EARLY THIS MORNING - MOSTLY
DRIVEN BY LOW LEVEL WARM AIR ADVECTION AND A WEAK RIPPLE IN THE
UPPER LEVEL FLOW. LOW LEVEL JET/MOISTURE TRANSPORT FOCUSED INTO LAKE
SUPERIOR WHILE LITTLE/IF ANY INSTABILITY INDICATED OVER THE FORECAST
AREA. STILL...MESO MODELS ALL POINT TO AN EXPANSION OF THE SHOWERS
AS THEY ADVANCE NORTHEAST...HINTING AT SOME THUNDER POTENTIAL TOO.

TO THE WEST...A LINE OF CONVECTION IS ONGOING...ASSOCIATED WITH AN
APPROACHING COLD FRONT. WHILE THE BOUNDARY ISN/T OVERLY IMPRESSIVE
IN TERMS OF A SAGGY PRESSURE GRADIENT...IT OBVIOUSLY HAS ENOUGH
FRONTOGENETIC FORCING TO POP SHOWERS/STORMS. THE FRONT WILL MOVE IN
THIS AFTERNOON...DROPPING SOUTHEAST OVERNIGHT. NAM BUILDS ABOUT 1 K
J/KG OF SBCAPE AHEAD OF THE BOUNDARY...WITH THE GFS MORE ROBUST AT
NEARLY TWICE THAT. SOME QUESTION ON HOW MUCH INSTABILITY WILL BE
REALIZED AS MORNING CONVECTION EXITS AND DEBRIS CLOUDS LINGER. IF
SEVERAL HOURS OF SUN DO RESULT IN GFS-ESQUE LIKE VALUES...BUFKIT
SOUNDINGS SHOW A RATHER SKINNY PROFILE TO CAPE...NOT SUPPORTIVE OF
DEEP/STRONG UPDRAFTS. IN ADDITION...WIND SHEAR IS RELATIVELY
MEAGER...MOSTLY POST THE FRONT...AND IN THE 0-3 KM LAYER.
OVERALL...NOT A FAVORABLE SCENARIO FOR SEVERE WEATHER. CAN/T RULE
OUT A FEW STRONGER STORMS...WITH SMALL HAIL AND ENHANCED WIND
GUSTS...BUT UNLESS STRONGER INSTABILITY DEVELOPS AND OVERLAPS WITH
THE MARGINAL SHEAR MORE...THE SEVERE RISK IS LOW.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 255 AM CDT FRI MAY 29 2015

THE GFS AND ECMWF FAVOR DRY CONDITIONS FOR THE WEEKEND AND MOST OF
NEXT WEEK. BOTH BUILD BROAD UPPER LEVEL RIDGING BY THE EARLY PART OF
NEXT WEEK...AMPLIFYING IT AS A WEST COAST TROUGH DEEPENS. THIS
AMPLIFICATION WOULD SERVE TO SHUFFLE MOST BITS OF ENERGY EJECTED OUT
OF THE TROUGH WEST/NORTH OF THE LOCAL FORECAST AREA. THAT SAID -
BOTH MODELS SUGGEST A BIT OF UPPER LEVEL ENERGY COULD SPIN ACROSS
THE REGION SUN NIGHT. THE PROBLEM FOR THIS RIPPLE IS THE AMOUNT OF
MOISTURE TO WORK WITH...WHICH IS MINIMAL VIA RH FIELDS/BUFKIT
SOUNDINGS. ALSO...A SFC HIGH IS SLATED TO BE JUST EAST OF THE LOCAL
AREA. WITH ALL THIS MIND...WILL KEEP MOST OF THE FORECAST AREA DRY
THROUGH WED...HOLDING ONTO SMALL CHANCES ACROSS THE FAR
NORTH...CLOSEST TO ANY FORCING. CONSENSUS SOLUTION GIVES SMALL POPS
FOR MUCH OF THE REGION ON THU/THU NIGHT. DON/T SEE A LOT OF SUPPORT
PER THE 00Z RUNS OF THE GFS/EC...BUT WILL HOLD WITH THIS FORECAST
FOR THE MOMENT. CAVEOT TO THE EXPECTED DRY CONDITIONS...IF THE RIDGE
ISN/T QUITE AS STRONG AS PROGGED...RAIN CHANCES WILL CREEP
INTO WESTERN/NORTHERN PARTS OF THE FORECAST AREA.

WITH THE PASSAGE OF THE COLD FRONT TODAY...COOL AIR RETURNS FOR THE
WEEKEND. 850 MB TEMPS PROGGED TO DROP FROM AROUND 14 C THIS
MORNING...TO 4 C BY 00Z SUN. NAEFS 850 MB TEMP STANDARD ANOMALIES
ARE ONLY 0 TO -1 SAT/SUN...SO ITS NOT AN ANOMALOUSLY COLD
AIRMASS...BUT WILL KEEP US A SEVERAL DEGREES BELOW THE LATE MAY
NORMALS. WITH THE BUILDING RIDGE FOR THE NEW WORK WEEK EXPECT TEMPS
TO REBOUND FOR THE START OF JUNE...WITH SOME 80S LOOKING LIKELY.

&&


.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1208 AM CDT FRI MAY 29 2015

A SHORT WAVE WILL PRODUCE SHOWERS AND POSSIBLY A THUNDERSTORM
OVERNIGHT AS IT MOVES NORTHEAST ACROSS THE AREA. CEILINGS WILL
REMAIN PRIMARILY VFR AT KLSE AND WILL BE MVFR AT KRST BETWEEN 29.11Z
AND 29.18Z.

ANOTHER ROUND OF SHOWERS WILL MOVE THROUGH THE AREA DURING THE
AFTERNOON AND EVENING. THERE MAY BE EVEN SOME SCATTERED
THUNDERSTORMS DURING THE AFTERNOON. CEILINGS WILL REMAIN MVFR AT
KRST...AND THEN LOWER TO MVFR AFTER 29.2230Z.

WINDS WILL BE SOUTHERLY THROUGH EARLY AFTERNOON AND THEN BECOME WEST
AND NORTHWEST AT KRST BETWEEN 29.20Z AND 29.23Z.

&&


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

$$

SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION.....BOYNE


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