Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 150523
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
123 AM EDT WED APR 15 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 108 PM EDT TUE APR 14 2015

NO PRECIP EXPECTED THROUGH THE DAY WEDNESDAY...AS UPPER MI REMAINS
DOMINATED BY DRY HIGH PRESSURE. TAKING A LOOK AT THE LAST COUPLE OF
SOUNDINGS FROM INTERNATIONAL FALLS MN...IT CONTINUES TO BE VERY DRY.
PW VALUES AROUND DAYBREAK WERE AROUND 0.17IN. AT 13Z THE RH VALUE AT
DLH WAS ALREADY BELOW 30 PERCENT. HUMIDITY VALUES CONTINUE TO FALL
THROUGH THE DAY WITH MIXING TO AROUND 800MB.

PW VALUES WILL REMAIN LESS THAN 0.25IN OVER THE E HALF OF UPPER MI
OVERNIGHT. THIS COMBINED WITH THE CLEAR SKY AND LIGHT WINDS...WILL
RESULT IN ANOTHER COOL NIGHT. THE TRADITIONAL COOL SPOTS OVER THE E
WILL LIKELY FALL INTO THE UPPER 20S.

ANOTHER DRY DAY IS ANTICIPATED WEDNESDAY. LOOK FOR INCREASING WINDS
OUT OF THE S OVER THE W HALF THIRD IN THE MORNING TO EXPAND OVER THE
W HALF DURING THE AFTERNOON HOURS. CLOSER TO THE NEARING AREA OF LOW
PRESSURE FROM CENTRAL MANITOBA THROUGH E CO AND FAR N TX. EXPECT
TEMPS TO MIX TO AROUND 850MB. ON A POSITIVE NOTE...THE STRONGEST
WINDS ABOVE THE SFC WILL BE OFFSET FROM OUR PEAK DAYTIME
HEATING/MIXING. STILL ANTICIPATING A FEW DAYTIME GUSTS NEARING 17-
20KTS. WITH HIGHS AGAIN IN THE 60S FOR MOST /EXCEPT IN THE 50S ALONG
LAKE MI/...AND ALL THE DRY AIR IN PLACE...AFTERNOON RH VALUES SHOULD
DROP INTO THE TEENS ONCE AGAIN FOR ALL BUT THE E THIRD OF THE CWA
AND THE N HALF OF THE KEWEENAW PENINSULA. AS NOTED IN THE PREVIOUS
DISCUSSION...WEDNESDAY WILL BE THIRD STRAIGHT DAY OF VERY LOW RH
VALUES...WHICH WILL INCREASE FIRE WX CONCERNS. THE COMBINATION OF
SSE WINDS AROUND 10KTS WITH GUSTS OF 15-20KTS ACROSS THE WEST...MAX
TEMPS ABOUT 15F ABOVE AVERAGE...AND AFTERNOON RH VALUES PLUMMETING
TO 15 TO 20 PERCENT WILL RESULT IN ELEVATED FIRE CONCERNS
FOR LOCATIONS THAT HAVE ALREADY LOST THEIR SNOWPACK.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 444 PM EDT TUE APR 14 2015

AS HAS BEEN THE CASE FOR THE LAST SEVERAL DAYS...THE LONG TERM
PORTION OF THE FCST HAS MORE THAN NORMAL UNCERTAINTY. THIS
UNCERTAINTY REVOLVES AROUND 2 ISSUES. THE FIRST IS THE TROF THAT IS
NOW OVER THE WRN STATES. ENERGY IN THIS TROF IS FCST TO SEPARATE OUT
OF THE MAIN FLOW AND FORM A CLOSED MID LEVEL LOW OVER THE SRN
ROCKIES IN THE COMING DAYS. THE SECOND ISSUE IS THE PROGRESSION OF
SHORTWAVES TO THE N IN THE MAIN FLOW...AND THE EVENTUAL SHARP
AMPLIFICATION OF THAT FLOW THAT WILL PICK UP THE CLOSED LOW OVER THE
SRN ROCKIES. THE DEGREE OF PATTERN AMPLIFICATION AND HOW IT
INTERACTS WITH THE CLOSED LOW WILL BE KEY TO WHAT HAPPENS HERE LATER
THIS WEEKEND/EARLY NEXT WEEK. RANGE OF POSSIBILITIES INCLUDE A
SIGNIFICANT RAIN EVENT TO A RAIN CHANGING TO ACCUMULATING SNOW EVENT
TO MINIMAL PCPN IF THE SRN SYSTEM DOES NOT LIFT FAR ENOUGH N AND W
WITHIN THE AMPLIFYING PATTERN. BASED ON GFS/GEM ENSEMBLES...A
SIGNIFICANT PCPN EVENT APPEARS TO BE THE LEAST LIKELY OUTCOME AT
THIS TIME. ALL OF THE MODELS HAVE BEEN STRUGGLING WITH THIS SCENARIO
FOR DAYS...LEADING TO A LOW CONFIDENCE FCST LATER THIS WEEKEND INTO
EARLY NEXT WEEK. WILL PROBABLY TAKE A FEW MORE DAYS BEFORE THE
OUTCOME IS MUCH MORE CERTAIN. IN THE MEANTIME...DRY/WARM WEATHER
WILL MOSTLY PREVAIL FOR THE REMAINDER OF THIS WEEK WITH THE MAIN
FLOW N OF THE AREA. THE AFORMENTIONED UPCOMING PRONOUNCED PATTERN
AMPLIFICATION THIS WEEKEND/EARLY NEXT WEEK WILL FEATURE A SHARP
RIDGE BUILDING N THRU WRN CANADA WITH DOWNSTREAM TROF PROBABLY
CENTERED IN THE HUDSON BAY TO GREAT LAKES REGION. THE OBVIOUS RESULT
OF THIS PATTERN CHANGE WILL BE A RETURN TO COLD CONDITIONS/BLO
NORMAL TEMPS NEXT WEEK. PATTERN LOOKS LIKE IT SHOULD SUPPORT
PERIODIC CHANCES OF SNOW/RAIN SHOWERS AS WELL.

BEGINNING WEDNESDAY NIGHT...MID-LEVEL RIDGING WILL SHIFT E OF THE
AREA WHILE DECAYING ENERGY FROM THE WEAKENING MID-LEVEL LOW
CURRENTLY OVER THE SRN PLAINS LIFTS INTO THE UPPER MISSISSIPPI
VALLEY/WRN LAKES. DRY AIR AT THE LOW AND MID LEVELS LINGERS WED
NIGHT WITH MAIN PUSH OF 850-700MB MOISTURE TRANSPORT TOWARD LWR MI.
THUS...NOT EXPECTING ANYTHING MORE THAN SOME THICKENING OF HIGH
CLOUDS.

ON INTO THU...WITH MOISTURE TRANSPORT INTO LWR MI WED NIGHT SHUNTED
EASTWARD BY SHORTWAVE IN THE MAIN FLOW TRACKING FROM MANITOBA TO
HUDSON BAY...IT APPEARS ANY LIGHT -SHRA ASSOCIATED WITH THE DECAYING
ENGERY LIFTING THRU THE GREAT LAKES WILL PASS E OF THE FCST AREA.
MEANWHILE...TAIL END OF SHORTWAVE TRACKING TO HUDSON BAY WILL
APPROACH THE UPPER LAKES LATE IN THE DAY AND PASS ACROSS THE AREA
THU NIGHT. FORCING FROM THE RIGHT ENTRANCE OF AN UPPER JET STREAK
AND MAIN DEEP LAYER QVECTOR CONVERGENCE PASS N OF THE AREA...
SUPPORTING BEST CHC OF -SHRA N OF HERE. ACROSS UPPER MI...VERY WEAK
FORCING/WEAK FRONTAL BOUNDARY AND WEAK MOISTURE TRANSPORT ALL
SUGGEST PROSPECT OF ANY -SHRA ARE VERY LIMITED AS SHORTWAVE PASSES.
THUS...PLAN TO MAINTAIN THE INHERITED DRY FCST FOR THU/THU NIGHT.
WITH WEAKENING PRES GRADIENT THRU THE DAY THU...WINDS WILL BE
LIGHTER THU AFTN THAN WED AFTN...HELPING TO EASE FIRE WX CONCERNS
EVEN THOUGH RH WILL FALL TO 20-25PCT OVER MUCH OF THE AREA.

IN THE MAIN FLOW TO THE N...ANOTHER SHORTWAVE IS FCST TO TRACK FROM
THE CANADIAN ROCKIES THU TO NRN ONTARIO/UPPER LAKES FRI. MODELS HAVE
OVERALL SHOWN SOME NORTHWARD TREND WITH THIS SHORTWAVE...BUT THERE
IS STILL PLENTY OF UNCERTAINTY. THE 00Z/12Z ECMWF ARE FARTHEST N...
RESULTING IN DRY WEATHER CONTINUING. 12Z NAM/GEM ARE FARTHER S. THE
12Z GFS IS NOT TOO MUCH DIFFERENT FROM THE 06Z GFS WHICH WAS QUITE
THE OUTLIER SHOWING WAVE DIGGING ENOUGH TO CATCH THE MID LEVEL LOW
OVER THE SRN ROCKIES. AS A RESULT...THE GFS DEVELOPS MUCH MORE PCPN
ACROSS THE AREA. WILL LEAN FCST TOWARD THE ECMWF...BUT WILL STILL
SHOW LOW POPS FOR -SHRA FRI/FRI NIGHT.

IN THE WAKE OF THE SHORTWAVE...HIGH PRES BUILDS INTO THE AREA FOR
SAT. WITH THE HIGH ENDING UP OVER LAKE SUPERIOR...IT WILL BE A MUCH
COOLER DAY NEAR LAKE SUPERIOR...ESPECIALLY FROM THE KEWEENAW
EASTWARD. RIGHT ALONG THE SHORE...TEMPS SHOULDN`T GET OUT OF THE
30S. IN THE INTERIOR W HALF...TEMPS SHOULD RISE TO NEAR 60F.

AS DISCUSSED EARLIER...UNCERTAINTY IS HIGH FOR SUN THRU TUE. 12Z
GUIDANCE TODAY DID NOT REALLY CLARIFY HOW THE PATTERN AMPLIFICATION
WILL INTERACT WITH THE MID LEVEL LOW THAT WILL BE OVER THE SRN
ROCKIES LATE WEEK/EARLY WEEKEND. GIVEN THE MAGNITUDE OF THE
SHARPENING RIDGE OVER WRN NAMERICA...SEEMS POSSIBLE FOR A
SIGNIFICANT SYSTEM/DEEP...COLD MID-LEVEL LOW TO EVOLVE DOWNSTREAM IN
THE GREAT LAKES REGION. WILL BE SOMETHING TO WATCH. FOR NOW...IT
APPEARS THE SRN ROCKIES ENERGY WILL GET PICKED UP AND FORCED NE TO
THE GREAT LAKES WITH SOME SORT OF INTERACTION WITH AMPLIFYING ENERGY
DIGGING SSE INTO THE MISSISSIPPI VALLEY REGION. FCST WILL REFLECT A
CONSENSUS APPROACH OF CURRENT/PREVIOUS MODELS...RESULTING IN CHC
POPS SPREADING INTO THE AREA LATE SUN AND CONTINUING THRU MON. CHC
FOR SHOWERY PCPN SHOULD CONTINUE INTO TUE ASSUMING TROF OVER THE
AREA OR DEEP COLD MID-LEVEL LOW DEVELOPMENT IN THE GREAT LAKES
REGION. PTYPE WILL SWITCH FROM RAIN INITIALLY SUN TO MAINLY SNOW
LATE MON INTO TUE.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 123 AM EDT WED APR 15 2015

VFR CONDITIONS WILL CONTINUE FOR THIS FORECAST PERIOD.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 108 PM EDT TUE APR 14 2015

NO SIGNIFICANT MARINE HAZARDS ARE ANTICIPATED THROUGH THE
PERIOD...WITH WINDS LESS THAN 30KTS. HIGH PRESSURE STRETCHING FROM S
HUDSON BAY THROUGH LOWER MI WILL DEEPEN OVERNIGHT AS IT SHIFTS TO
JAMES BAY-LAKE HURON. EXPECT THIS AREA OF HIGH PRESSURE TO EXIT INTO
QUEBEC WEDNESDAY AFTERNOON AND EVENING AS LOW PRESSURE OVER MANITOBA
SURGES NE TO S HUDSON BAY. THE LINGERING RIDGE ACROSS LAKE SUPERIOR
WEDNESDAY NIGHT INTO EARLY THURSDAY WILL BE REPLACED BY A TROUGH
EXTENDING FROM THE HUDSON BAY LOW...THAT WILL LINGER THROUGH FRIDAY.
THIS TROUGH WILL BE REINFORCED BY AN ADDITIONAL LOW OVER CENTRAL
CANADA THURSDAY NIGHT...THAT WILL CROSS ONTARIO ON FRIDAY. LOOK FOR
HIGH PRESSURE AVERAGING TO SLIDE BACK INTO THE UPPER GREAT LAKES
REGION SATURDAY AFTERNOON THROUGH SUNDAY.
&&

.HYDROLOGY...
ISSUED AT 108 PM EDT TUE APR 14 2015

CONTINUE TO SEE HIGHER WATER LEVELS AT A FEW RIVERS...MAINLY THE
TRAP ROCK RIVER IN HOUGHTON COUNTY...THE CHOCOLAY RIVER IN
HARVEY...AND THE STURGEON RIVER AT NAHMA JUNCTION...THE STURGEON
RIVER NEAR ALSTON IN BARAGA COUNTY...THE PRICKETT DAM DOWNSTREAM TO
THE CONFLUENCE WITH OUTFLOW FROM OTTER LAKE DAM...AND THE ESCANABA
RIVER. LOW END ADVISORIES AND OTHER STATEMENTS STILL LOOK REASONABLE.

OTHER RIVERS...LIKE THE MICHIGAMME RIVER IS SLOWLY RISING
TOO...THANKS TO SNOW STILL UPSTREAM /NEAR THE PESHEKEE RIVER/.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...KF
LONG TERM...ROLFSON
AVIATION...07
MARINE...KF
HYDROLOGY...KF


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