FXUS63 KMPX 021816
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1216 PM CST WED DEC 2 2009
.AVIATION... /18Z TAF ISSUANCE/
LOW PRESSURE ALOFT OVER NORTH DAKOTA WILL MOVE SOUTHEAST TO
SOUTHERN MN DURING THE TAF PERIOD. THIS FEATURE WILL AID IN LIGHT
SNOW OR SNOW SHOWERS SPREADING ACROSS THE MN TAF SITES TONIGHT AND
THURSDAY AND ACROSS WEST CENTRAL WI DURING THE DAY TOMORROW WITH
MVFR CONDITIONS. HOWEVER...CEILINGS/VISIBILITIES QUITE VARIABLE RIGHT
NOW AT THE TAF SITES WITH KRNH SCT AND KAXN AT 4SM BR OVC005. THE
LOW CONDITIONS AT KAXN IS STRETCHES NW TO KGFK AND SE TO KULM. THIS
IS WHERE A LOW LEVEL THERMAL RIDGE RESIDES ALONG WITH AN AXIS OF
HIGHER DEW POINTS. THIS STRUCTURE WILL MOVE SLOWLY SE DURING THE
PERIOD AND IS ALSO WHERE THE BEST CHANCE FOR SN0W EXISTS TONIGHT
AND EARLY THURSDAY. WINDS WILL BE N TO NW AT 8 TO 12 KNOTS THROUGH
THE PD. ADDITIONAL DETAILS FOR EACH SITE BELOW.
KAXN...LIFR CONDITIONS ARE EXPECTED TO IMPROVE TO AT LEAST IFR
THIS AFTERNOON. THIS IS SUPPORTED BY CLIMATOLOGY WITH SHOWS
CONDITIONS BETTER THAN 500 FEET BY 22Z. ALSO MOS GUIDANCE SUGGEST
HIGHER CONDITIONS. SNOW SHOWERS EXPECTED INTO KAXN THIS EVENING AS
FORCING AND DEEPER LAYER MOISTURE ARRIVES AHEAD OF THE UPPER LOW.
EXPECT 2-4 MILES DURING THE NIGHT WITH CEILINGS IFR/LOW MVFR.
GRADUAL IMPROVEMENT TO MVFR ON THURSDAY IN THE WAKE OF THE UPPER LOW.
KRWF...CLEARING JUST WEST OF KRWF ATTM BUT IT IS EXPECTED TO STAY
TO THE WEST WITH VFR CEILINGS SLOWLY BECOMING MVFR BY LATE THIS
AFTERNOON AND CONTINUING TONIGHT AND THURSDAY. FLURRIES EXPECTED
AROUND MIDNIGHT WITH 3-5 MILE VISIBILITY IN SNOW LATE IN THE
NIGHT AND THURSDAY MORNING.
KSTC...VFR CEILINGS WILL GIVE WAY TO MVFR EARLY TONIGHT. FLURRIES
EXPECTED LATE IN THE EVENING WITH 4-6 MILE VISIBILITY IN SNOW LATE
IN THE NIGHT AND THURSDAY MORNING.
KMSP...MVFR CEILINGS PREVAIL ATTM...BUT CLEARING IS JUST NORTH
AND EAST OF KMSP. BACK EDGE IS MOVING SLOWLY SW WITH POTENTIAL
FOR BKN035 AROUND 21Z. INDICATED THIS IN THE TAF WITH VFR CEILINGS
EXPECTED THIS EVENING. MVFR CEILINGS EXPECTED TO DEVELOP BY
MIDNIGHT WITH FLURRIES POSSIBLE BY DAYBREAK. BEST SNOW SHOWER
POTENTIAL IN THE 03/18 TO 04/00Z TIME FRAME WITH 3-5 MILE
VISIBILITY POSSIBLE.
KRNH...MAINLY CLEAR SKIES OVER THE SITE WILL SLOWLY FILL IN THIS
AFTERNOON WITH SCT-BKN CU AROUND THE 030 FOOT LEVEL. MVFR CEILINGS
THEN FORECAST FOR TONIGHT AND THURSDAY. FLURRIES EXPECTED AT
03/12Z WITH MVFR VISIBILITIES POSSIBLE AFTER 03/18Z.
KEAU...BKN-OVC MVFR CEILINGS EXPECTED THROUGH THE TAF PERIOD.
FLURRIES POSSIBLE AT 03/15Z WITH BETTER POTENTIAL FOR MVFR
VISIBILITIES IN SNOW SHOWERS AFTER 03/21Z.
&&
.DISCUSSION... /ISSUED 148 AM CST WED DEC 2 2009/
WINTER CONTINUES TO ARRIVE ON NORTHWEST WINDS AND WILL INTO
TODAY AND TONIGHT...WITH COLDER TEMPERATURES AND OCCASIONAL
FLURRIES/SNOW SHOWERS THE NEXT FEW DAYS OFFERING THE CHALLENGES TO
THE FORECAST.
NORTHERN HEMISPHERIC WV LOOP SHOWING ROSSBY WAVE TROUGH SETTING
UP OVER NORTH AMERICA...WITH COLD AIR/LOW THICKNESSES FINALLY
BEGINNING TO REDISTRIBUTE INTO THE WRN HEMISPHERE. WITHIN CURRENT
SYNOPTIC TROUGH DIGGING INTO THE CENTRAL U.S. THE COLDEST 500MB
TEMPS WERE SEEN AT KCYD NORTH OF LAKE WINNIPEG LAST EVE...WITH A
ROBUST -38C. THIS COLD POCKET WILL SINK SOUTH INTO OUR AREA AND
MODIFY SOME AS IT DOES. THIS AREA AND ITS ENHANCED LAPSE RATES AND
VORT MAXS WILL OFFER THE BEST CHANCE FOR SNOW SHOWERS AND FLURRIES
THIS AFTN IN WEST CTRL MN AND TONIGHT INTO THU ACROSS THE REST OF
THE CWA. THE NAM AND GFS MODELS ARE IN GOOD AGREEMENT WITH THIS
WITH TIMING CONFIDENCE OF THE SREF. HAVE USED AS FORECAST TOOLS
THE AFOREMENTIONED MID-LEVEL COLD POCKET...LOW LEVEL LAPSE
RATES...AND 850-700MB VORT LAYERS. ALL IN ALL...GOOD AGREEMENT
WITH THE PREVIOUS FORECAST WITH JUST SOME INCREMENTAL INCREASES IN
POPS IN THE NEXT 12-36 HOURS.
FOR TODAY...WHILE A FEW HOLES MAY EXIST THIS MORNING...AFTN SFC
LAPSE RATES AND ASSOCIATED CU RULE FROM THE NAM MODEL FAVOR OVC
STRATOCU BY AFTN. COLD AIR ADVECTION CONTINUES IN THE LOW LAYERS
WITH VERY MODEST HEATING TODAY...SO HAVE ONLY 3 TO 6 DEGREE
TEMPERATURE CLIMBS. SOME SNOW SHOWERS SHOULD BE SEEN IN NW TO SE
BANDS ACROSS WEST CTRL MN BY AFTN. THE 4KM NMMWRF PAINTS THIS
PICTURE...WHICH AGREE WELL WITH VORT PLACEMENT ON THE NAM/GFS.
WITH MID-LEVEL THERMAL TROUGH DIRECTLY OVER THE AREA TONIGHT AND
THU...WENT WITH PRIMARILY SCT WORDING FOR SNOW SHOWERS. ACCUMS
SHOULD BE NOTHING OR MINOR WHERE THEY OCCUR AS LITTLE IN THE WAY OF
BROAD OMEGA IS PAINTED . ITS POSSIBLE THAT 0.5 TO 1 INCH MAY FALL
IN A FEW PLACES IN WEST CTRL OR CTRL MN. FOR TEMPS HAVE BUMPED UP
MINS A BIT WITH SO ROBUST OF CLOUD COVER MINIMIZING THE TEMP
RANGE...BUT OVERALL THE DAILY OSCILLATION KEEPS FALLING THROUGH
FRI. SO BY FRI MORNING AND SAT MORNING...LOWS IN THE TEENS WITH
ISOLATED SINGLE DIGITS UNDER DEVELOPING CLOUD HOLES ARE EXPECTED.
WHEN THE CLOUDS BREAK UP STILL REMAINS SOMEWHAT UNCERTAIN...WITH
THE BEST ESTIMATE ON SAT OR SAT NIGHT AS LONG WAVE TROUGH CENTER
WORKS A BIT FURTHER NORTH IN ERN CANADA. TEMPS SHOULD BE NEAR
NORMAL THIS WEEKEND...WITH ANY PRECIP FORCING VERY LIGHT. RIGHT
NOW CONTINUE WITH NO MENTION. FORECAST CONFIDENCE FOR THE FIRST
HALF OF NEXT WEEK DROPS QUICKLY. PACIFIC NW TROUGH EXPECTED TO
SHIFT EASTWARD IN PIECES ON THE MODEL GUIDANCE BUT TIMING AND
DEPTH OF WAVES VARY SIGNIFICANTLY. WITH JET AND BAROCLINIC ZONE
FOCUSED TO OUR SOUTH...TEMPS FOR NEXT WEEK CERTAINLY LOOK BELOW
NORMAL. WILL HAVE TO MAINTAIN PATIENCE FOR SNOW CHANCES.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
RAH/MTF
