Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
421 AM EDT FRI MAY 22 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 420 AM EDT FRI MAY 22 2015

VERY DRY HIGH PRESSURE OVERHEAD. PW VALUES OF 0.15 TO 0.3IN /HIGHEST 
FAR W/ AT 09Z WILL REMAIN NEARLY STEADY STATE THIS MORNING. SOME OF 
THIS DRY AIR CAN BE SEEN BY VIEWING THE VERY LOW DEW POINTS OF 12-
13F FROM THE MARQUETTE COAST GUARD DOWN TO SAW. 

PW VALUES WILL INCREASE TO 0.25 TO 0.35IN BY MID AFTERNOON. 
HOWEVER...PEAK HEATING WITH TEMPS RISING INTO THE LOW TO MID 60S 
OVER THE INTERIOR W HALF /50S E/ WILL COMBINE WITH DEW POINTS OF 20-
25F /TEENS E/ TO RESULT IN 6-9 HOURS OF 20-25 PERCENT RH. THE LAKE 
BREEZE OFF LAKE SUPERIOR WILL BE STRONGEST OVER THE E HALF OF UPPER 
MI...WITH WINDS OUT OF THE NW FUNNELING TOWARDS THE SOO. AFTERNOON 
GUSTS OF 15-20KTS WILL BE COMMON OVER THE FAR E.

AS FOR TONIGHT...WITH THE SFC HIGH EXITING TO THE LOWER GREAT 
LAKES/OHIO VALLEY...LOOK FOR THE RETURN OF W-SW WINDS. 850MB TEMPS 
WILL INCREASE FROM AROUND 3C TO 9C OVER THE FAR W. LOWS IN THE 
TRADITIONAL DOWNSLOPE AREAS W ALONG LAKE SUPERIOR WILL REMAIN IN THE 
LOW TO MID 40S OVERNIGHT...WHILE THE REST OF THE CWA FALLS INTO THE 
30S. A WEAK TROUGH ATTEMPTING TO BREAK DOWN THE SFC RIDGE OVERNIGHT 
MAY BRING A FEW LIGHT SHOWERS TO LAKE SUPERIOR /POSSIBLY CLIPPING 
THE KEWEENAW PENINSULA AS INDICATED BY THE GFS AND NAM SOLUTIONS/.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 249 AM EDT FRI MAY 22 2015

NAM SHOWS A RIDGE ACROSS THE SERN U.S. POKING UP INTO THE UPPER 
GREAT LAKES WITH A CLOSED LOW OVER THE CENTRAL ROCKIES 12Z SAT. THE 
PATTERN DOES NOT CHANGE MUCH FOR 12Z SUN WITH THE LOW FURTHER 
NORTHEAST AND THE RIDGE STILL OVER THE UPPER GREAT LAKES. THE LOW 
AND TROUGH MOVE INTO THE NORTHERN PLAINS ON SUN NIGHT. NAM BRINGS IN 
SOME 850-500 MB Q-VECTOR CONVERGENCE AND DEEPER MOISTURE FROM THE 
SOUTH ON SUN INTO SUN NIGHT. WILL START TO BRING IN SOME POPS SUN 
AFTERNOON WITH CHANCE POPS IN THE FAR WEST AND SOUTH AND THEN 
INCREASE POPS TO LIKELY OVER THE SOUTHERN HALF OF THE CWA SUN NIGHT. 
WILL ALSO GO DRIER FOR SAT AND SAT NIGHT AND CONTINUE THE DRY 
WEATHER INTO SUN AFTERNOON. FRONT UP TO THE NORTH WILL KEEP POPS TO 
THE NORTH OF THE AREA SAT. OTHERWISE...DID NOT MAKE TOO MANY CHANGES 
TO THE GOING FORECAST.

IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB RIDGE OVER THE SERN 
U.S. 12Z MON WITH A BROAD TROUGH OVER CENTRAL AND EASTERN CANADA AND 
A TROUGH IN THE WESTERN U.S. THE TROUGH IN THE WESTERN U.S. BREAKS 
OFF A PIECE OF ENERGY AND PUSHES UP AGAINST THE RIDGE WITH A 
SHORTWAVE OVER THE UPPER GREAT LAKES 12Z TUE. THIS TROUGH REMAINS 
OVER THE UPPER GREAT LAKES INTO 12Z WED WITH A SFC FRONT POISED JUST 
TO THE NORTH OF LAKE SUPERIOR. THIS SFC FRONT HEADS SOUTH THROUGH 
THE UPPER GREAT LAKES 12Z THU WITH A SHORTWAVE THAT MOVES INTO THE 
NORTHERN PLAINS. TEMPERATURES LOOK TO STAY ABOVE NORMAL THIS 
FORECAST PERIOD AND WITH SFC FRONTS IN THE AREA...RAIN CANNOT BE 
RULED OUT AT ANY TIME WITH CHANCE POPS FOR MOST OF THIS PERIOD.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1208 AM EDT FRI MAY 22 2015

HIGH PRES SETTLING OVER THE UPPER GREAT LAKES WITH ASSOCIATED DEEP 
DRY AIR MASS WILL RESULT IN CLEAR SKIES/VFR CONDITIONS AT 
KIWD/KCMX/KSAW THRU THIS FCST PERIOD. CALM/NEAR NEAR CALM WIND 
OVERNIGHT WILL TRANSITION TO LIGHT LAKE BREEZES TODAY.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 420 AM EDT FRI MAY 22 2015

WINDS WILL GENERALLY BE LESS THAN 25KTS. HOWEVER...THE HIGHER 
OBSERVING PLATFORMS MAY PICK UP HIGHER READINGS OUTSIDE OF THE 
SHALLOW MARINE LAYER. HIGH PRESSURE ACROSS THE UPPER GREAT LAKES 
WILL EXIT TO THE MID ATLANTIC STATES BY SATURDAY MORNING...WITH A 
RIDGE LINGERING ACROSS LAKE SUPERIOR. A WEAK TROUGH WILL BRUSH E 
LAKE SUPERIOR SATURDAY AS IT TRACKS SE ACROSS ONTARIO /WHICH WILL 
BRING THE HIGHEST CHANCE OF WINDS GUSTING AT OR ABOVE 25KTS THROUGH 
THE PERIOD...OVER MAINLY N LAKE SUPERIOR/. A RIDGE OF HIGH PRESSURE 
WILL RETURN TO THE GREAT LAKES REGION SATURDAY NIGHT INTO SUNDAY. 
EXPECT A LOW OVER THE CENTRAL AND S PLAINS SUNDAY MORNING TO DEEPEN 
ACROSS S MN AND IA BY DAYBREAK MONDAY...AND W LAKE SUPERIOR DURING 
THE DAYTIME HOURS MONDAY. THIS LOW WILL MERGE WITH A LOW PUSHING 
ACROSS CENTRAL CANADA MONDAY NIGHT...AND THEN LINGER ACROSS W LAKE 
SUPERIOR THROUGH TUESDAY.
&&

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

$$

SHORT TERM...- NONE -
LONG TERM...07
AVIATION...ROLFSON
MARINE...KF

National Weather Service Glossary of Abbreviations