Area Forecast Discussion
Issued by NWS Duluth, MN

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000
FXUS63 KDLH 270539
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1239 AM CDT WED AUG 27 2014

.UPDATE...
ISSUED AT 1239 AM CDT WED AUG 27 2014

UPDATED AVIATION DISCUSSION BELOW.

UPDATE ISSUED AT 848 PM CDT TUE AUG 26 2014

APPROACHING AREA OF RAIN IS HOLDING TOGETHER QUITE WELL UNDERNEATH
NARROW BAND OF STRONG ASCENT ASSOCIATED WITH THE APPROACHING WAVE.
WHILE THE FORCING WILL BE SLOWLY WEAKENING WITH TIME AS THIS WAVE
MOVES FARTHER EAST..THERE STILL SHOULD BE A 1-2 HOUR PERIOD OF
SHOWERS OR LIGHT RAIN ACROSS MANY AREAS ALONG/SOUTH OF ROUGHLY A
BIGFORK/VIRGINIA/TWO HARBORS/ASHLAND LINE OVERNIGHT. THUS..WE HAVE
UPDATED THE FORECAST ONCE AGAIN TO PUSH POPS/SKY COVER UPWARD AND
EXPAND COVERAGE A BIT FARTHER NORTH AND EAST..AS WELL AS UPPING QPF
AMOUNTS BY A FEW HUNDREDTHS OF AN INCH.

UPDATE ISSUED AT 703 PM CDT TUE AUG 26 2014

RATHER IMPRESSIVE LOW AMPLITUDE S/W TROF CONTINUES TO MOVE
STEADILY/RAPIDLY EASTWARD ACROSS THE DAKOTAS THIS EVENING. WHILE
THIS DISTURBANCE HAS LITTLE IN THE WAY OF QUALITY MOISTURE TO WORK
WITH AND VIRTUALLY NO INSTABILITY..THE STRENGTH OF THE PV LOBE IS
RATHER IMPRESSIVE..AND THERE APPEARS TO BE SOME AIDING
CONTRIBUTION FROM JET ENTRANCE REGION DYNAMICS AND COUPLING WITH
SOME WEAK MID LEVEL FGEN AS EVIDENCED IN RADAR AND W/V SAT IMAGERY.
WHILE THIS SYSTEM WILL NOT BE AN OVERLY BIG DEAL AS IT TRACKS
RAPIDLY EASTWARD ACROSS THE REGION OVERNIGHT..IT SHOULD BE ABLE TO
SPREAD SOME LIGHT RAIN OR SHOWERS ACROSS ROUGHLY THE SOUTHERN HALF
OF THE CWA FOR A 3-5 HOUR PERIOD IN ANY ONE LOCATION SOMETIME
BETWEEN ROUGHLY 9 PM OUT WEST THROUGH AROUND 6 AM OVER NW
WISCONSIN. FORCING SHOULD BE GRADUALLY WEAKENING WITH TIME..SO
COVERAGE MAY BE WANING TOWARD DAYBREAK.

WE HAVE UPDATED THE VARIOUS GRIDS AND ASSOCIATED TEXT PRODUCTS TO
REFLECT HIGHER CLOUD COVER AND PRECIP CHANCES ACROSS THE
SOUTH..AND ALSO INCREASED HUMIDITY FORECASTS WITH SLIGHTLY GREATER
COVERAGE OF LIGHT RAIN OR SPRINKLES.

UPDATED AVIATION DISCUSSION FOR THE 00Z TAFS IS ALSO BELOW.

&&

.SYNOPSIS...
ISSUED AT 316 PM CDT TUE AUG 26 2014

MID LVL PATTERN FEATURES TWO BRANCHES OF THE UPPER JET ACROSS CONUS
WITH THE NRN BRANCH MAINTAINING A VERY PROGRESSIVE CHARACTER. WV
LOOP SHOWS AN APPROACHING SHORTWAVE TROF LOCATED OVER NWRN NODAK.
SOUTHERN BRANCH OF WESTERLIES HAS AMPLIFIED OVER THE ROCKIES WITH A
BACKING FLOW SUPPLYING INCREASING MID/HIGH LVL MOISTURE INTO THE
CTRL PLAINS.  THIS IS EVIDENT ON SAT IMAGERY WITH CLOUDS ADVECTING
INTO THE REGION FROM THE SOUTHWEST. MEANWHILE RESIDUAL CUMULUS ARE
OCCURRING IN THE BACK EDGE OF A SOMEWHAT CYCLONIC FLOW LEFT IN WAKE
OF PREVIOUS SYSTEM. GUSTY WEST/NW WIND STILL IN PLAY OVER ARROWHEAD
AND TWIN PORTS. 88D RETURNS OVER NRN PLAINS SHOW AN EAST TO WEST
ORIENTED BAND OF PRECIP ON THE RETURN FLOW SIDE OF A SFC HIGH. THIS
APPEARS TO BE RELATED TO AN AREA OF LOW/MID LVL FRONTOGENESIS
OCCURRING WITHIN CONFLUENCE OF THE TWO UPPER JET BRANCHES.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 316 PM CDT TUE AUG 26 2014

TONIGHT...FAST MOVING SHORTWAVE TROF WILL CROSS CWA OVERNIGHT WITH
AREA OF MID LVL FRONTOGENESIS SUPPORTING INCREASING CLOUDS/LIGHT
PRECIP. SFC HIGH IS FCST TO SWING EAST IN TANDEM WITH THIS FEATURE.
ALTHOUGH OVERALL FORCING/SATURATION APPEARS ON THE WEAK/LOW SIDE
WITH THIS SYSTEM...HARD TO IGNORE INCREASING ECHOES OVER THE NRN
PLAINS. ALL MDL OUTPUT NOW INDICATING LIGHT QPF ACROSS SRN
HALF/THIRD OF CWA. INCREASED THE AREAL EXTENT OF PREVIOUS POPS
HOWEVER STILL MAINLY A SLIGHT CHC EVENT.

TOMORROW...AFOREMENTIONED MID LVL TROF WILL SCOOT QUICKLY EAST WITH
SFC HIGH THE DOMINANT FEATURE. LIGHT WIND REGIME EXPECTED WITH
INCREASED LOW LVL THICKNESSES/925 TEMPS. MAX TEMPS SHOULD LIFT ABOUT
3 TO 5 DEGREES ABOVE TODAYS VALUES.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT  316 PM CDT TUE AUG 26 2014

WITH THE SURFACE HIGH DRIFTING EAST OF THE AREA WEDNESDAY NIGHT
THERE WILL BE AN INCREASE IN WARM WARM WHERE WE SEE THE 8H TEMPS
RISING INTO THE TEENS BY FRIDAY. A SFC LOW WILL DEVELOP IN THE LEE
OF THE ROCKIES AS THE  UPPER TROF DIGS AND DEEPENS INTO THE SW
STATES. WHILE THIS SW UPPER LOW IS SLOWLY MOVING EAST A SERIES OF
UPPER LEVEL VORT MAXES WILL SPIN UP THROUGH THE TROUGH AND INTO SRN
MN.  WE`LL SEE SUCH A SYSTEM THURSDAY. THUNDERSTORMS WILL
GRADUALLY SPREAD NORTH ACROSS MN AND WI WEDNESDAY NIGHT...AND THEN
INTO NRN PORTIONS OF THE STATES THURSDAY. THERE WILL BE STRONG FGEN
ALONG AND NORTH OF THE BAROCLINIC ZONE ACROSS SRN MN AND CENTRAL
WI...WHICH WILL PUT THE AREA FROM PINE CITY ACROSS EAST TO PHILLIPS
WI AND SOUTH IN THE BEST LIFT AREA. HOWEVER...WE`RE NOT SEEING A LOT
OF INSTABILITY AND STABLE LAPSE RATES. THE NEXT CHANCE OF RAIN WILL
BE ON FRIDAY NIGHT AND SATURDAY WITH THE PASSAGE OF A COOL
FRONT...THE BEGINNING OF NEXT WEEK LOOKS TO BE WET AS ANOTHER UPPER
LOW MOVES SLOWLY ACROSS THE CANADIAN PROVINCES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1239 AM CDT WED AUG 27 2014

A FAST-MOVING DISTURBANCE BROUGHT PERIODS OF LIGHT RAIN TO MOST
AIRPORTS THIS EVENING. SHOWERS ARE EXPECTED TO CONTINUE FOR
SEVERAL HOURS AT BRD/DLH/HYR. THE INCREASE IN LOW-LEVEL MOISTURE
FROM THE RAINS WILL LEAD TO LOW VSBYS AND MVFR/IFR CONDITIONS
OVERNIGHT. THE DISTURBANCE WILL EXIT THE REGION BY MID-MORNING
LEAVING A SURFACE RIDGE AS THE MAIN WEATHER FEATURE. VSBYS/CIGS
WILL IMPROVE LATER THIS MORNING WITH VFR CONDITIONS EXPECTED FOR
THE REST OF THE PERIOD.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  53  68  56  72 /   0  20  30  20
INL  47  74  54  76 /   0  10  10  20
BRD  55  73  57  77 /  10  30  20  10
HYR  51  70  56  74 /   0  40  40  20
ASX  51  71  56  72 /   0  20  30  20

&&

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

$$

UPDATE...MILLER
SHORT TERM...CANNON
LONG TERM...CLC
AVIATION...HUYCK






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