Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 251944
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
344 PM EDT FRI JUL 25 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 343 PM EDT FRI JUL 25 2014

12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A WNW FLOW ALF
OVER THE UPR LKS BTWN DEEP CLOSED LO OVER NRN QUEBEC AND SHRTWV RDG
AXIS EXTENDING NNEWD INTO MN/NW ONTARIO FM CENTER OF HIER HGTS OVER
THE SRN ROCKIES. ALTHOUGH SLOW INFLUX OF MOISTER AIR IN THE GENERAL
SW FLOW BTWN SFC/H85 HI OVER THE MID ATLANTIC STATES AND LOWER MSLP
IN THE NRN PLAINS ASSOCIATED WITH A DEEP CLOSED LO IN SRN
SASKATCHEWAN THAT IS RIDING OVER THE RDG CENTERED IN THE SRN ROCKIES
HAS ALLOWED FOR A GOOD DEAL OF CLDS/A FEW SHOWERS OVER MAINLY THE W
HALF OF THE CWA TDAY...MAIN FOCUS FOR HEAVIER PCPN HAS BEEN WELL TO
THE SW CLOSER TO SHARP H85 WARM FNT STRETCHING FM THE DAKOTAS INTO
THE MID MS RIVER VALLEY. HI STABILITY SHOWN ON THE 12Z INL RAOB AND
ESPECIALLY THE GRB RAOB...WHICH DEPICTS A SHARP INVRN ARND H75...HAS
TENDED TO LIMIT THE INTENSITY AND COVERAGE OF THE SHOWERS THAT HAVE
IMPACTED UPR MI. OVER THE ERN CWA...VERY DRY/STABLE AIRMASS SHOWN ON
THE 12Z APX RAOB HAS ALLOWED FOR MORE SUNSHINE. BUT TO THE W...MORE
SHOWERS ARE PRESENT IN NE MN/WRN LK SUP IN AREA OF HIER H85 THETA E
ADVCTN IN ADVANCE OF A WEAK SHRTWV MOVING E ALONG THE CNDN BORDER
ARND CLOSED LO IN SASKATCHEWAN. BUT EWD PUSH OF DRIER AIR IN THE NRN
PLAINS IS TENDING TO LIMIT THE OVERALL COVERAGE OF THESE SHOWERS AS
WELL.

MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE PCPN CHCS ASSOCIATED
WITH SHRTWV NOW MOVING ALONG THE CNDN BORDER.

LATE TDAY/TNGT...EXPECT AREA OF SHOWERS NOW IN NE MN AND A FEW
TS...THE POTENTIAL OF WHICH WL BE LIMITED BY PERSISTENT HIER MID LVL
STABILITY DEPICTED BEST ON THE GFS FCST SDNGS...TO SPREAD W-E INTO
UPR MI WITH AREA OF POSITIVE H85 THETA E ADVCTN THAT WL LIFT PWAT UP
TO ARND 1.5 INCHES/AXIS OF SOME H85-5 QVECTOR CNVGC IN ADVANCE OF
SHRTWV NOW TRACKING E ALONG THE CNDN BORDER. BUT ARRIVAL OF DRY AIR
NOW IN THE NRN PLAINS WL TEND TO DIMINISH THE POPS LATER EVEN THOUGH
THERE ARE HINTS A 2ND SHRTWV MIGHT FOLLOW INTO THE UPR LKS. FCST
LARGE SCALE QVECTOR DVGC OVER THE W LATE INDICATES THE DRYING WL
OVERCOME ANY PVA ASSOCIATED WITH THIS TRAILING SHRTWV. GOING FCST
POPS ARE IN PRETTY GOOD SHAPE AND NEED ONLY SMALL ADJUSTMENTS.
DESPITE THE MID LVL DRYING LATE...DVLPG LO CLDS WL LIMIT THE DIURNAL
TEMP FALL.

SAT...ANY LINGERING MRNG SHOWERS OVER MAINLY THE NE CWA WL END WITH
ARRIVAL OF DRIER AIR ALF THAT WL DEPRESS PWAT TO 0.75-1.0 INCH/DNVA
AND DEEP LYR QVECTOR DVGC AHEAD OF SHRTWV RDG TRAILING THE DEPARTING
2ND SHRTWV. WITH MRNG LO CLDS GIVING WAY TO MORE SUNSHINE AND FCST
H85 TEMPS AS HI AS 17-18C OVER THE W BY 00Z SUN...EXPECT MAX TEMPS
TO RISE INTO THE 80S AWAY FM THE MODERATING INFLUENCE OF THE GREAT
LKS. GIVEN THE MID LVL DRYING/POTENTIAL FOR DEEP MIXING AND NEAR
ADIABATIC LLVL LAPSE RATES...PREFER THE HIER END OF GUIDANCE FOR MAX
TEMPS...AT LEAST OVER THE INTERIOR W HALF. SOME OF THE HIER RES
MODELS...MAINLY THE 12Z NAM AND REGIONAL CNDN MODEL...DO INDICATE
THIS DAYTIME HEATING WL TRIGGER SOME SHOWERS/TS OVER THE ERN CWA IN
THE AFTN WITH CONVERGING LK BREEZES OFF LKS SUP/MI UNDER SOMEHWAT
LOWER HGTS. THE MAIN LIMITING FACTOR FOR THE DLPMNT OF THESE LK
BREEZE SHOWERS/TS WL BE THE DRYING ALF THAT IS FCST TO MIX TO THE
SFC WITH THE DAYTIME HEATING. IN FACT...DEEP MIXING ON THE GFS/NAM
FCST SDNGS HINT SFC DEWPTS OVER THE INTERIOR W HALF COULD MIX OUT AS
LO AS 45-50 LATE IN THE DAY...WITH KINX DROPPING TO 15-20. THE NAM
FCST SDNG FOR NEWBERRY AT 18Z SHOWS SBCAPE ARND 2K G/KG FOR SFC T/TD
OF 75/65. PREFER THE MORE CONSERVATIVE GFS FCST FOR SFC T/TD OF
75/60 AND SBCAPE CLOSE TO 700 J/KG. DESPITE THE LIMITATION OF THE
LARGE SCALE DRYING...WL MAINTAIN SOME LO CHC POPS OVER THE ERN CWA
TO ACCOUNT FOR THE LK BREEZE CNVGC.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 451 AM EDT FRI JUL 25 2014

A SOMEWHAT ACTIVE WEATHER PATTERN WILL BE IN PLACE ACROSS THE REGION
THROUGH THE WEEKEND...WITH A SIGNIFICANT COOLDOWN STARTING SUNDAY
AND EXTENDING INTO NEXT WEEK.

ON SATURDAY...THE FORECAST AREA WILL REMAIN UNDER ZONAL W-NW FLOW
ALOFT WITH THE LEFT EXIT REGION OF THE JET AND ASSOCIATED SHORT
WAVE EXITING TO THE EAST. ANY REMAINING SHOWER ACTIVITY FROM FRI
NIGHT SHOULD EXIT AS WELL AS DRY ADVECTION MOVES ACROSS THE AREA.
THIS WILL ALLOW FOR CLEARING SKIES WITH TEMPERATURES TO WARM INTO
THE MID-UPPER 70S ACROSS THE AREA. ALL THE NUMERICAL GUIDANCE
SUGGEST THAT INSTABILITY WILL INCREASE ACROSS THE EASTERN HALF OF
THE FORECAST AREA DURING THE AFTERNOON IN RESPONSE TO THE DIURNAL
HEATING. ALTHOUGH THE FORECAST CAPE VALUES OF 1000-2000 J/KG IS
LIKELY TOO HIGH DUE TO THE NORMAL HIGH BIAS OF SFC DEW
POINTS...THERE WILL LIKELY STILL BE INSTABILITY OF AT LEAST 1000
J/KG DURING THE LATE MORNING/AFTERNOON SIMPLY DUE TO THE STEEPER
LAPSE RATES ALOFT OF 6.5 C/KM. AS SUCH...HAVE OPTED TO MAINTAIN
CHANCE POPS ACROSS THE EASTERN LAKE BREEZE AREAS DURING THE
AFTERNOON HOURS ESPECIALLY WITH THE NAM AND GFS KEEPING THE LEFT
EXIT REGION OF THE JET AND ASSOCIATED WEAK Q-VECTOR CONVERGENCE IN
THIS AREA DURING THE AFTERNOON. THE BIG LIMITING FACTOR FOR MORE
WIDESPREAD CONVECTION WILL BE THE DRY AIR ALOFT...AND LACK OF
SIGNIFICANT LOW LEVEL FORCING OTHER THAN THE LAKE BREEZE ACTIVITY.
THIS AGREES WELL WITH THE HIGH RES NUMERICAL GUIDANCE THAT SUGGEST A
FEW STORMS ALONG THE LAKE BREEZE DURING THE DAY.

ON SATURDAY NIGHT INTO SUNDAY...THE UPPER LOW CURRENTLY OVER ALBERTA
WILL MOVE TOWARD THE AREA. MEANWHILE...THE UPPER LOW NE OF JAMES BAY
WILL RETROGRADE SLIGHTLY TO THE WEST AND SOUTH. THESE TWO FEATURES
WILL ALLOW FOR THE FRONT TO THE NORTH OF THE AREA TO MOVE ACROSS THE
REGION LATE SAT NIGHT INTO SUNDAY MORNING. AS THIS OCCURS...LOW
PRESSURE ASSOCIATED WITH THE UPPER LOW TO THE WEST WILL MOVE ALONG
THE FRONT ON SAT NIGHT INTO SUNDAY...TRACKING SOUTH OF THE AREA.
SHOWER AND ISOLATED STORMS WILL MOVE INTO THE AREA LATER SAT NIGHT
AHEAD OF THE UPPER LOW...THEN SPREAD ACROSS THE ENTIRE FORECAST AREA
ON SUNDAY. SUNDAY SHOULD END UP BEING A FAIRLY COOL AND DAMP DAY
WITH A BRISK /AT LEAST FOR SUMMER/ NORTH WIND. TEMPERATURES WILL
REMAIN FAIRLY STEADY IN THE 60S ACROSS THE AREA. IN FACT...IT WOULD
NOT BE SURPRISING IF TEMPS WILL FALL DURING THE DAY ESPECIALLY
CLOSER TO LAKE SUPERIOR AS 850MB TEMPS DROP TO 10C BY SUN EVENING.
THE GOOD NEWS IS THAT THE RAIN SHOULD RAPIDLY END LATE SUN AFTERNOON
INTO SUNDAY EVENING AS THE LOW MOVES EAST OF THE AREA. HOWEVER...BY
MONDAY MORNING 850MB TEMPS WILL DROP TO +6C WHICH WILL ALLOW FOR A
COOL NIGHT SUNDAY NIGHT. MONDAY WILL BE TRANQUIL AS WELL WITH STABLE
NORTH WINDS AND BUILDING HIGH PRESSURE ACROSS THE UPPER GREAT LAKES.

FOR THE TUE-THU TIME PERIOD...THE UPPER GREAT LAKES WILL REMAIN
BELOW NORMAL WITH THE DEEP TROUGH PERSISTING ACROSS THE EASTERN HALF
OF THE U.S. THROUGH THE PERIOD. THE UPPER LOW JUST EAST OF HUDSON
BAY WILL REMAIN FAIRLY STATIONARY THROUGH THE PERIOD. WEAK UPPER
LEVEL SHORT WAVES WILL ROTATE AROUND THE UPPER LOW AND ACROSS THE
AREA...WHICH WILL MAKE TIMING OF PRECIPITATION SOMEWHAT DIFFICULT.
HOWEVER...WITH THE COLD TEMPERATURES ALOFT COMBINED WITH FAIRLY
FREQUENT DISTURBANCES ALOFT...EXPECT THE BEST CHANCES FOR SHOWERS
AND STORMS TO BE DURING THE PEAK HEATING HOURS IN THE AFTERNOON AND
EARLY EVENING HOURS EACH DAY. OTHERWISE...TEMPERATURES WILL REMAIN
BELOW NORMAL THROUGH THE PERIOD.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 129 PM EDT FRI JUL 25 2014

WITH INFLUX OF MOISTER AIR IN LLVL SW FLOW AND APRCH OF AN UPPER
DISTURBANCE...EXPECT SHRA AND AREA OF MVFR CLDS NEAR IWD TO
OVERSPREAD CMX AND SAW BY THIS EVNG. WITH SOME DRYING ALF LATE TNGT
THAT WL END THE SHOWERS...EXPECT IFR CONDITIONS TO DVLP IN THE
PRESENCE OF DIURNAL COOLING. LIFR CONDITIONS ARE NOT OUT OF THE
QUESTION. THE ARRIVAL OF DRIER AIR AND DAYTIME WL RESULT IN
IMPROVEMENT TO VFR ON SAT. THIS PROCESS WL BE SLOWEST AT CMX WITH AN
UPSLOPE W WIND.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 427 AM EDT FRI JUL 25 2014

EXPECT WINDS UNDER 15 KTS THRU SAT NIGHT WITH RELATIVELY WEAK PRES
GRADIENT DOMINATING THE UPPER LAKES. STRONGER N WINDS UP TO 20-25
KTS ARE POSSIBLE ON SUN INTO MON AS COOLER AIR INVADES THE AREA
UNDER TIGHTER GRADIENT BETWEEN HI PRES MOVING INTO THE NORTHERN
PLAINS AND LO PRES OVER THE SE GREAT LAKES. WINDS WILL DIMINISH ON
TUE AND BACK TOWARD THE W WITH CLOSER APPROACH OF HI PRES FROM THE
PLAINS.
&&

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

$$

SHORT TERM...KC
LONG TERM...MRD
AVIATION...KC
MARINE...TITUS




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