Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 280448
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1148 PM CDT MON APR 27 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 239 PM CDT MON APR 27 2015

STILL EXPECTING THE QUIET WEATHER TO CONTINUE THROUGH THE MIDDLE
OF THE WEEK DESPITE THE PASSAGE OF A SYSTEM ACROSS THE UPPER
MIDWEST TUESDAY AND TUESDAY NIGHT. THE HIGH PRESSURE RIDGE OVER
THE REGION FROM THE LARGE SURFACE HIGH OVER ONTARIO WILL
TEMPORARILY RETREAT TO THE THE NORTH AHEAD OF THE APPROACHING
SYSTEM. THE 27.12Z MODELS ARE ALL IN GOOD AGREEMENT THAT THE MAIN
PART OF THE SHORT WAVE TROUGH WITH THE UPCOMING SYSTEM WILL PASS
BY TO THE NORTH...BUT THE VERY SOUTHERN EDGE OF IT WILL MOVE
ACROSS. THIS MAY BE ENOUGH TO PRODUCE SOME VERY WEAK PV ADVECTION
IN THE 500-300 MB LAYER TUESDAY AFTERNOON AND EVENING. THE ONLY
OTHER FORCING THAT LOOKS TO BE IN PLACE WITH THIS SYSTEM IS SOME
WEAK FRONTOGENESIS IN THE 850-500 MB LAYER WITH THE PASSAGE OF THE
COLD FRONT. MOISTURE RETURN TO THE AREA WILL PRACTICALLY BE NON-
EXISTENT AS THE LARGE CUT OFF LOW OVER THE TEXAS PANHANDLE WILL
SLOWLY PROGRESS EAST AND INTERCEPT ANY MOISTURE TRYING TO WORK
NORTH FROM THE GULF. THE COMBINATION OF WEAK FORCING AND LACK OF
MOISTURE SHOULD ALLOW THE SYSTEM TO PASS THROUGH WITHOUT PRODUCING
ANY RAIN AND SHOULD JUST BE NOTED BY A GENERAL INCREASE IN THE
CLOUD COVER.

WITH THE RETREAT OF THE SURFACE RIDGE...THE DEW POINT DROP TUESDAY
AFTERNOON SHOULD NOT BE AS DRAMATIC AS RECENT DAYS. STILL
EXPECTING CENTRAL WISCONSIN TO MIX OUT SOME WITH DEW POINTS
DIPPING INTO THE MIDDLE 30S WHICH SHOULD YIELD AN AFTERNOON
MINIMUM HUMIDITY BETWEEN 25 AND 30 PERCENT. THE WINDS STILL LOOK
TO BE RELATIVELY LIGHT...OUT OF THE NORTH AT 10 MPH OR LESS. AS
THE RIDGE AXIS THEN STARTS TO REESTABLISH ITSELF WEDNESDAY...THE
MIXING SHOULD AGAIN CAUSE THE DEW POINTS TO DIP INTO THE MIDDLE
30S FOR AN AFTERNOON MINIMUM HUMIDITY AGAIN BETWEEN 25 AND 30
PERCENT.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 239 PM CDT MON APR 27 2015

STILL EXPECTING A PATTERN SHIFT TO OCCUR LATE IN THE WEEK. THE
UPPER LEVEL RIDGE AXIS OVER THE CENTRAL CONUS WILL GET FLATTENED
BY SHORT WAVE TROUGHS COMING IN OFF THE PACIFIC. ONCE THIS
HAPPENS...THESE INCOMING WAVES WILL HAVE THE OPPORTUNITY TO
PRODUCE SOME RAIN ACROSS THE REGION. THE FIRST CHANCE WILL COME
FRIDAY AND FRIDAY NIGHT...BUT THE GENERAL CONSENSUS AMONG THE
27.12Z MODELS IS THAT THIS WAVE WILL WEAKEN AS IT BUMPS INTO THE
REMAINS OF THE RIDGE. THIS WILL RESULT IN JUST SOME LOW RAIN
CHANCES TIED TO THE PASSAGE OF THE WEAK FRONT AND SHORT WAVE
TROUGH. THE MODELS THEN START TO DIVERGE ON THE TIMING...POSITION
AND STRENGTH OF THE SUBSEQUENT SHORT WAVE TROUGHS. WITH THESE
DIFFERENCES...PLAN TO STAY CLOSE TO THE MODEL CONSENSUS WITH A
GRADUAL INCREASE IN THE RAIN CHANCES STARTING SATURDAY NIGHT WITH
THE BEST CHANCES CURRENTLY CENTERED ON SUNDAY NIGHT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1145 PM CDT MON APR 27 2015

HIGH PRESSURE WILL PROVIDE CLEAR SKIES THROUGH TUESDAY MORNING.
MID AND HIGH CLOUDS WILL INCREASE ACROSS THE AREA DURING THE EARLY
AFTERNOON AS A WEAKENING COLD FRONT MOVES TOWARD THE AREA.
CEILINGS WILL LOWER INTO THE 4 TO 6K RANGE DURING THE LATE
AFTERNOON AND EVENING...AND THEN PERSIST THROUGH THE REMAINDER OF
THE EVENING. WINDS WILL REMAIN OUT OF THE NORTH AND NORTHWEST AT
10 KNOTS OR LESS THROUGH THE PERIOD.

&&

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

$$

SHORT TERM...04
LONG TERM...04
AVIATION...BOYNE



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