Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 061158
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
558 AM CST FRI MAR 6 2015

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 304 AM CST FRI MAR 6 2015

SFC RIDGE AXIS WAS LOCATED OVER THE EASTERN EDGE OF THE FORECAST
AREA AT 08Z. MEANWHILE...A FRONTAL BOUNDARY WAS MOVING THROUGH NW
MN. ALOFT...THERE WAS A VORT MAX MOVING ALONG THE INTERNATIONAL
BORDER REGION ALONG WITH AN UPPER LEVEL TROF. THESE FEATURES WERE
GENERATING MID AND HIGH CLOUDS OVER MN HEADING FOR WI. ATMOSPHERE IS
VERY DRY BELOW 8K FT AS SEEN ON 00Z INL SOUNDING AS WELL AS FORECAST
SOUNDINGS. HAVE REMOVED THE MENTION OF FLURRIES AS A RESULT. THE
FRONT WILL CONTINUE ACROSS THE FORECAST AREA TODAY ASSISTED BY
ANOTHER UPPER LEVEL TROF. MOISTURE IS SPARSE WITH THE PASSAGE OF
THESE FEATURES AND HAVE REMOVED THE POPS...LIGHT SNOW/FLURRIES
MENTION. REDUCED THE CLOUD COVER AS WELL. WAA IS EXPECTED THROUGH
THE DAY WHICH WILL LEAD TO WARMER TEMPERATURES...BUT DID LOWER THEM
A BIT FROM PREVIOUS FORECAST AS ALBEDO FACTOR WILL BE HIGH WITH THE
LACK OF CLOUDS THROUGH EARLY AFTERNOON. CLOUDS WILL BE ON THE
INCREASE LATE IN THE AFTERNOON AHEAD OF NEXT UPPER TROF AND
ASSOCIATED SFC LOW.

MODEL DIFFERENCES SHOW UP TONIGHT WITH REGARD TO THE
TIMING/DEVELOPMENT OF LIGHT SNOW. GFS IS THE FASTEST AND HAS BEEN
IGNORED. USED A BLEND OF THE ECMWF/GEM/NAM FOR TIMING OF THE SNOW
WHICH MEANS POPS JUST FOR THE WESTERN THIRD OF THE FORECAST AREA
THIS EVENING. BEST OPPORTUNITY FOR LIGHT SNOW WILL BE OVERNIGHT WHEN
THE SFC LOW MOVES ALONG THE INTERNATIONAL BORDER AND REACHES NEAR
THUNDER BAY BY 12Z SATURDAY. THE BEST MOISTURE/FORCING WILL BE FOUND
IN THE VCNTY OF THE LOW WHICH WILL ALSO BE AIDED BY A POTENT VORT
MAX ACCOMPANYING THE SFC LOW. HAVE THE HIGHEST POPS ALONG THE
INTERNATIONAL BORDER REGION. UP TO ONE INCH OF SNOW IS POSSIBLE OVER
THE TIP OF THE ARROWHEAD WITH LIGHTER AMOUNTS ELSEWHERE.

ON SATURDAY MORNING...THE SFC LOW MOVES QUICKLY TO THE EASTERN GREAT
LAKES WHILE A TRAILING COLD FRONT MOVES THROUGH THE AREA. NOT MUCH
MOISTURE IS AVAILABLE FOR THIS FRONT...EXCEPT NEAR THE ARROWHEAD AND
KEPT SOME POPS THERE AS A RESULT. GFS IS TOO WET AND HAS BEEN
TOSSED. KEPT THE COMPROMISE FROM THE OTHER MODELS. A NW FLOW
DEVELOPS OVER LAKE SUPERIOR WITH CAA ALOFT. HOWEVER...THE LOW LEVELS
WILL REMAIN FAIRLY WARM WHICH WILL PRECLUDE ANY ACCUMULATIONS. HAVE
A SMALL POP OVER IRON COUNTY ANYWAY. EVEN THOUGH THE CAA PATTERN
PERSISTS THROUGH THE AFTERNOON...SO DOES THE WARM LOW LEVEL TEMPS
AND KEPT THE SMALL POPS AS AN ELONGATED AREA OF VORTICITY MOVES
NEARBY. LOWERED THE MAX TEMPS A BIT ON SATURDAY WITH THE ANTICIPATED
CAA.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 304 AM CST FRI MAR 6 2015

CONFIDENCE IN THE EXTENDED PERIOD IS LOWER THAN IT HAS BEEN. THERE
ARE BOTH DIFFERENCES BETWEEN THE GFS AND ECMWF...AS WELL AS SOME
INCONSISTENCY WITHIN EACH MODEL. THIS IS ESPECIALLY TRUE BEYOND
TUESDAY. THESE DIFFERENCES WILL IMPACT BOTH THE PRECIPITATION
FORECAST AND ESPECIALLY TEMPERATURES WHICH MAY NOT WARM AS MUCH AS
EARLIER FORECAST.

NORTHWEST FLOW ALOFT WILL SEND ANOTHER IN A SERIES OF SHORTWAVES
THROUGH THE NORTHLAND SATURDAY NIGHT INTO SUNDAY. A TROUGH AT THE
SURFACE WILL BE ASSOCIATED WITH THE UPPER FEATURE AS WELL. WE
INCREASED POPS LATE SATURDAY NIGHT INTO SUNDAY MORNING...MAINLY OVER
FAR NORTHERN AREAS WHERE SOME LIGHT ACCUMULATION WILL BE POSSIBLE.

WEAK LOW LEVEL RIDGING WILL DEVELOP LATE SUNDAY INTO SUNDAY NIGHT
AND SHOULD LEAD TO DRY CONDITIONS.

WE KEPT THE FORECAST DRY MONDAY THROUGH THURSDAY AS OVERALL THE MAIN
STORM TRACK WILL REMAIN NORTH OF THE INTERNATIONAL BORDER. THERE IS
SOME SUPPORT FOR LIGHT PRECIP MID WEEK AS A COLD FRONT AND A WEAK
WAVE IMPACT THE AREA. HOWEVER...THESE FEATURES DO NOT LOOK
PARTICULARLY STRONG SO WE LEFT THE FORECAST DRY FOR NOW. THE GFS IS
MUCH COLDER BY WEDNESDAY SENDING 850MB TEMPERATURES TO -14C ALONG
THE INTERNATIONAL BORDER BY 12Z WED. THE LATEST RUN OF THE ECMWF HAS
ALSO COOLED QUITE A BIT OVER ITS PREVIOUS RUN...BUT NOT AS MUCH AS
THE GFS. THE GFS IS FURTHER WEST AND SOUTH AND SLIGHTLY STRONGER
WITH THE LOW LEVEL HIGH/RIDGE WHICH PUSHES THE COLDER AIR FURTHER
SOUTH INTO THE NORTHLAND. WE COOLED TEMPS SOME FOR WEDNESDAY...BUT
DID NOT COMPLETELY BUY INTO THE GFS.

THE UPPER RIDGE WILL CONTINUE A SLOW MOVEMENT EAST WITH IT BECOMING
LESS AMPLIFIED BY MIDWEEK. THE SURFACE HIGH IS FORECAST TO MOVE
SOUTH AND EAST OF THE REGION BY THURSDAY WHICH WILL CREATE AN
ONSHORE FLOW AROUND LAKE SUPERIOR. THE GEM SUPPORTS THE WARMER ECMWF
ON THURSDAY. WE DID COOL HIGHS WEDNESDAY/THURSDAY...BUT DID NOT GO
AS LOW AS THE GFS.. WINDS OFF OF LAKE SUPERIOR WILL ALSO KEEP
LAKESIDE TEMPERATURES COOLER AND WE DID DROP THOSE TEMPS SOME.

WE HAVE HIGHS IN THE THIRTIES SUNDAY...THEN WARM THEN INTO THE
FORTIES ON TUESDAY. WE COOLED TEMPS WEDNESDAY INTO THE MID THIRTIES
NORTH TO MID FORTIES FAR SOUTH...AND HAVE THEM MAINLY IN THE
THIRTIES ON THURSDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 557 AM CST FRI MAR 6 2015

A TROUGH OF LOW PRESSURE WILL PASS THROUGH THE NORTHLAND TODAY
CAUSING WINDS TO SWITCH FROM SOUTHERLY TO WESTERLY. THERE WERE
SOME MID CLOUDS OVER PORTIONS OF THE NORTHLAND...BUT THEY WILL
DIMINISH FROM WEST TO EAST THIS MORNING. THERE MAY BE SOME
HIGH MVFR/LOW VFR CLOUDS THAT DEVELOP AROUND 18Z...BUT WE DO NOT
EXPECT THEM TO BECOME BROKEN THIS AFTERNOON.

ANOTHER SHORTWAVE AND AREA OF LOW PRESSURE WILL IMPACT THE
NORTHLAND TONIGHT. LIFT WITH THIS SYSTEM IS STRONGER AND THERE
WILL BE A CHANCE FOR SNOW AND MVFR CEILINGS AS IT PASSES THROUGH.
WINDS WILL BACK AHEAD OF THE SYSTEM THEN VEER BACK TO WESTERLY AS
IT PASSES THROUGH LATE IN THE PERIOD INTO SATURDAY MORNING.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  30  21  30  17 /   0  40   0  30
INL  28  18  26  15 /   0  30  10  50
BRD  33  22  32  19 /   0  30   0  20
HYR  30  21  32  15 /   0  30   0  20
ASX  31  23  32  16 /   0  40  10  20

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&

$$

SHORT TERM...GSF
LONG TERM...MELDE
AVIATION...MELDE





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