FXUS63 KDLH 231137
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
537 AM CST WED DEC 23 2009
.AVIATION...12Z TAFS
COMPLEX CLOUD FORECAST AGAIN THIS MORNING. EASTERLY WINDS WILL
CONTINUE...BETWEEN HIGH PRESSURE OVER NORTHWEST ONTARIO...AND LOW
PRESSURE CURRENTLY WELL TO THE SOUTHWEST. MVFR AND ISOLATED IFR
CEILINGS WERE OVER OR BEING GENERATED BY THE GREAT LAKES THIS
MORNING....WITH ANOTHER AREA ASSOCIATED WITH WAA OVER C-S
MINNESOTA/WISCONSIN. ONE AREA OF LOWER CEILINGS WAS MOVING OFF OF
LAKE SUPERIOR INTO THE ARROWHEAD AND BORDER COUNTRY. TEMPERATURES
ARE FORECAST TO INCREASE TODAY...AND THE STABILITY SHOULD INCREASE
AND DIMINISH THE AMOUNT OF CLOUD BEING GENERATED. THERE WAS ALSO
SOME LOWER CLOUD IN A PORTION OF EC WISCONSIN...AND THAT SHOULD
REMAIN OUT OF THE KHYR TAF SITE. THE MODELS DO SHOW LOWER HUMIDITY
WORKING EAST TO WEST TODAY...AND THAT SHOULD DECREASE THE THREAT OF
MVFR CEILINGS THROUGH THE LATE MORNING AND AFTERNOON.
LOW PRESSURE WILL BE MOVING NORTH TODAY AND ESPECIALLY TONIGHT INTO
THURSDAY. MVFR CEILINGS WILL MOVE IN FROM SOUTH TO NORTH...WITH A
CHANCE FOR LIGHT SNOW. THE LOWER CEILINGS WILL AFFECT KBRD
FIRST...AND KINL LATE TONIGHT. IFR VSBYS IN SNOW WILL ALSO BE
POSSIBLE LATE TONIGHT FOR MOST TAF SITES.
&&
.PREV DISCUSSION... /ISSUED 454 AM CST WED DEC 23 2009/
DISCUSSION...MAJOR WINTER STORM IS THE MAIN FOCUS FOR THIS PERIOD.
LOW CLOUDS CONTINUE TO STREAM OFF LAKE SUPERIOR THIS MORNING...
ALTHOUGH SO FAR THERE HAS BEEN LITTLE IN THE WAY OF SNOW SHOWER
ACTIVITY. WILL CONTINUE TO MENTION A CHANCE OF SNOW SHOWERS ACROSS
THE NORTH SHORE...AS THE POTENTIAL WILL REMAIN DURING THE DAY.
OTHERWISE...FAIRLY QUIET FOR THE MOST PART TODAY.
BEYOND TODAY...THE FOCUS QUICKLY SHIFTS TO THE DEVELOPING WINTER
STORM THAT WILL AFFECT THE REGION DURING THE ENTIRE CHRISTMAS
HOLIDAY. THE MODELS ARE GRADUALLY COMING INTO SOMEWHAT BETTER
AGREEMENT...ALTHOUGH MODEL QPF VARIES CONSIDERABLY. IN TERMS OF
THE MASS FIELDS...THE ECMWF AND NAM SEEM TO MAKE THE MOST SENSE
AND HAVE UTILIZED A BLEND OF THESE TWO SOLUTIONS. NO MATTER
WHAT...THERE IS SUFFICIENT EVIDENCE TO UPGRADE THE WINTER STORM
WATCH TO A WINTER STORM WARNING FOR THE ENTIRE CWA.
A STRONG NORTHERN STREAM CLOSED LOW AND SHORTWAVE WILL DROP
SOUTHWARD TODAY...EVENTUALLY MERGING/CONSOLIDATING WITH THE
SOUTHERN STREAM SHORTWAVE EJECTING OUT OF THE SOUTHERN TROUGH.
STRONG UPWARD VERTICAL MOTION AHEAD OF THE CONSOLIDATING UPPER
LEVEL LOW...COMBINED WITH FAVORABLE JET DYNAMICS AND ABUNDANT
MOISTURE SHOULD RESULT IN IMPRESSIVE SNOWFALL...WITH SNOWFALL
RATES OF AN INCH TO AN INCH AND A HALF PER HOUR AT TIMES.
THE AREA FROM BRAINERD TO SIREN WAS ALREADY IN A WARNING...BUT
WILL BUMP UP THE TIME TO START AT MIDNIGHT TONIGHT RATHER THAN 6
AM CHRISTMAS EVE. MODEL QPF SOLUTIONS GENERALLY BRING A QUARTER
INCH OF QPF TO THAT AREA BY 12Z THURSDAY.
MODEL RUN QPF FORECASTS THROUGH 12Z SATURDAY ARE QUITE VARIED...
WITH THE GFS BRINGING ABOUT AN INCH TO DULUTH THROUGH THAT TIME.
THIS 06Z SOLUTION IS DOWN FROM THE 00Z SOLUTION OF AROUND 1.5
INCHES. THE NAM BRINGS 2.65 INCHES OF LIQUID EQUIVALENT
QPF...WHILE THE ECMWF BRINGS AROUND 1.60 INCHES OF PRECIPITATION.
THE SREF BRINGS 1.86 INCHES OF QPF. THE GEM BRINGS AROUND 1.25
INCH. DESPITE THE MYRIAD OF SOLUTIONS REGARDING QPF...EVEN THE
LOWEST QPF SOLUTION WOULD TRANSLATE INTO SOME PRETTY IMPRESSIVE
SNOWFALL TOTALS. HAVE KEPT WITH A 10 TO 14 INCH FORECAST...BUT IF
THE HIGHER QPF FROM THE NAM DOES PAN OUT...WE COULD BE TALKING
ABOUT MUCH MORE IN SPOTS. GIVEN THE MOISTURE AVAILABLE AND THE
PROLONGED SNOW EVENT...WE COULD SEE SOME LOCALIZED 18+ AMOUNTS
BEFORE ALL IS SAID AND DONE SOMETIME SATURDAY. AT THIS POINT...THE
CORRIDOR OF HIGHEST SNOWFALL LOOKS TO BE FROM EC MN INTO THE NORTH
SHORE. THE GFS ENSEMBLE FORECASTS ARE SHOWING REMARKABLE
CONTINUITY AMONGST THE VARIOUS MEMBERS...AND GIVE CONFIDENCE TO
CURRENT SNOWFALL AMOUNTS. BASED ON FORECAST SOUNDINGS...THERE
COULD BE SOME SLEET OR FREEZING RAIN FOR A TIME IN NW WI. THIS
COULD RESULT IN SOMEWHAT REDUCED AMOUNTS IN NW WI DUE TO THE
VARIOUS PRECIPITATION TYPES.
THURSDAY NIGHT THROUGH TUESDAY...THE MODELS CONTINUE TO BE IN
GENERAL AGREEMENT MOVING THE 500MB LOW INTO THE CENTER OF THE
COUNTRY BY 12Z FRIDAY...HAVING IT SOMEWHERE IN THE KS/MO/NE AREA.
THE SURFACE LOW IS THEN LOCATED IN DIFFERENT AREAS...FROM
SOUTHWEST IA TO EASTERN IA...HOWEVER THE CENTRAL PRESSURE IS
WITHIN A FEW MILLIBARS OF EACH OTHER. THE GFS ENSEMBLE MEMBERS
CONTINUE TO SHOWS GOOD CLUSTERING IN EASTERN IA AT 12Z
FRIDAY...AND THE GFS ENSEMBLE MEAN AND ECMWF ARE CLOSELY LOCATED
THERE. SNOW COVERAGE AND INTENSITY SHOULD INCREASE THURSDAY NIGHT
AS THE DEEPENING SURFACE LOW MOVES NORTH AND WITH GOOD
WAA/MOISTURE TRANSPORT INTO OUR CWA. THE ECMWF HAS E/SE WINDS AT
850MB OF 40-55KT. WE INCREASED WINDS THURSDAY NIGHT NEAR LAKE
SUPERIOR...AND THERE SHOULD BE A GOOD AMOUNT OF BLOWING AND
DRIFTING SNOW. THERE WILL BE LOCALIZED WHITE-OUT CONDITIONS THAT
DEVELOP...ESPECIALLY AROUND THE TWIN PORTS AREA.
THERE ARE STILL QUESTION MARKS REGARDING SNOW TOTALS IN THE THURSDAY
NIGHT THROUGH FRIDAY NIGHT PERIOD. THE MODELS ALL DIFFER ON THEIR
TIMING OF HEAVIEST QPF. WE WENT WITH THE HIGHEST SNOW/QPF THURSDAY
NIGHT. THE MODELS ALSO CONTINUE TO BRING WARMER AIR INTO OUR
NORTHWEST WISCONSIN ZONES. WE ADDED A MENTION OF FREEZING RAIN TO
THE SLEET AND SNOW WE HAD GOING FOR THURSDAY NIGHT AND FRIDAY. THE
LOW WILL PINWHEEL ON FRIDAY INTO FRIDAY NIGHT...WITH THE ECMWF
MOVING IT LITTLE. THE MODELS ALSO SHOW SOME DRIER AIR ALOFT ROTATING
NORTHWEST FURTHER INTO OUR CWA...WHICH MAY CAUSE THE PRECIP TO
DIMINISH IN INTENSITY FURTHER AT TIMES...ALLOWING SOME FREEZING
DRIZZLE TO OCCUR. AT THIS TIME...WE CONFINED THE FREEZING DRIZZLE
MENTION TO OUR NORTHWEST WISCONSIN ZONES...BUT LATER FORECASTS WILL
BE ABLE TO ADD MORE DETAIL AND IT MAY HAVE TO BE SPREAD FURTHER WEST
AND NORTH.
THE MODELS DIVERGE ON HOW THEY HANDLE THE LOW SATURDAY INTO
SUNDAY...WITH THE ECMWF SLOWEST TO MOVE IT OUT OF OUR CWA. WE WILL
CONTINUE TO MENTION LIGHT SNOW SATURDAY INTO SUNDAY...BUT
ACCUMULATIONS WILL GENERALLY BE LIGHT.
AVIATION.../06Z TAF ISSUANCE/
BANK OF MVFR STRATUS STRETCHES ACROSS SRN AND WRN PARTS OF THE CWA
AT 06Z. THIS CLOUD COVER WILL SLOWLY EDGE NORTH THROUGH THE TAF
PD. ADDITIONAL STRATUS BEING ADVECTED OFF OF LAKE SUPERIOR WILL
AFFECT KHIB AND KINL...AND POTENTIALLY KDLH AS WELL...BETWEEN 08Z
AND 12Z. MEANWHILE...MOISTURE WILL CONT TO INC FROM THE SOUTH
AHEAD OF MAJOR WINTER STORM SET TO AFFECT THE NORTHLAND. SNOW WILL
BEGIN TO AFFECT KBRD AND POSSIBLY KHYR AT THE END OF THIS TAF
PD...SPREADING NORTH AND EAST TO AFFECT REMAINING TERMINALS AFT
06Z THUR.
&&
.POINT TEMPS/POPS...
DLH 28 17 28 26 / 10 50 100 100
INL 23 13 23 21 / 10 10 90 90
BRD 28 21 29 27 / 10 90 100 100
HYR 29 22 30 27 / 10 70 90 100
ASX 28 22 30 27 / 10 40 90 100
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM CST SATURDAY
FOR MNZ033-034-036-038.
WINTER STORM WARNING FROM 6 AM THURSDAY TO 6 AM CST SATURDAY FOR
MNZ010>012-018>021-025-026-035-037.
WI...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM CST SATURDAY
FOR WIZ006-007.
WINTER STORM WARNING FROM 6 AM THURSDAY TO 6 AM CST SATURDAY FOR
WIZ001>004-008-009.
LS...SMALL CRAFT ADVISORY UNTIL 6 PM CST FRIDAY FOR LSZ121-140>148.
&&
$$
MELDE/DAP
