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000
FXUS63 KAPX 250705
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
305 AM EDT FRI JUL 25 2014

.SYNOPSIS...
ISSUED AT 303 AM EDT FRI JUL 25 2014

HIGH PRESSURE WILL GIVE WAY TO A FAST MOVING SYSTEM TONIGHT AND 
SATURDAY. CLOUDS WILL BE ON THE INCREASE TODAY...WITH A CHANCE FOR 
SHOWERS AND A FEW THUNDERSTORMS TONIGHT INTO THE START OF THE 
WEEKEND. A MUCH STRONGER SYSTEM WILL ARRIVE TO END THE WEEKEND... 
BRINGING BETTER POTENTIAL FOR SHOWERS SUNDAY AND SUNDAY NIGHT. A 
RETURN TO MUCH BELOW NORMAL TEMPERATURES ON MONDAY...WITH ONLY A 
SLOW MODERATION EXPECTED THROUGH THE REMAINDER OF THE WEEK.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 303 AM EDT FRI JUL 25 2014

...MORE CLOUDS AND A SHADE WARMER WITH STORM CHANCES TONIGHT...

IMPACTS: LIGHTNING...BUT NO SEVERE WEATHER EXPECTED.

CURRENT WEATHER AND SYNOPTIC PATTERN:

BROAD UPPER RIDGING SEEN OVER THE SW PART OF THE COUNTRY WHILE 
TROUGHING IS STILL THE THEME OVER THE EASTERN CONUS. THE RIDGING HAS 
BEEN SQUASHED DUE TO A WRAPPED UP CLOSED LOW DRIFTS ACROSS SW 
CANADA. THIS HAS INDUCED LOW PRESSURE OVER EASTERN CANADA AND THE 
NRN PLAINS. AN AXIS OF DEEP THETA-E AIR...LEADING EDGE OF STEEP 
LAPSE RATES ALOFT (6.5C/KM-7.5C/KM) AND LLJ (45-55KT) CONVERGENCE 
AHEAD OF THE PLAINS SFC LOW HAS RESULTED IN POCKETS OF SHOWERS AND 
STORMS IN THE DAKOTAS DOWN TO NE. CLOSER TO HOME...AREA VAD WIND 
PROFILES AND RUC ANALYSIS SHOWING A TROUGH AXIS AND H8 MOISTURE 
ADVECTION FROM THE ARROWHEAD OF MN DOWN THROUGH WISCONSIN. THERE 
WERE A FEW ELEVATED RETURNS...BUT ONLY A FEW SPRINKLES HITTING 
GROUND PER AREA OBS. OVER NRN MICHIGAN...WE ARE STILL UNDER THE 
INFLUENCE OF SFC HIGH PRESSURE...BUT THOSE SAME VAD WIND PROFILES 
SHOW THAT THIS HAS SHIFTED JUST EAST OF US WITH A RETURN TO A SW 
WIND. AIR MASS IS STILL QUITE DRY WITH PWATS RELATIVELY LOWER THAN 
ANYWHERE NEARBY. ONLY A BAND OF HIGHER LEVEL CLOUD STREAMING DOWN 
THROUGH THE NW FLOW ALOFT. THE DRY AIR AND MOSTLY CLEAR SKIES HAVE 
ALLOWED TEMPERATURES TO FALL INTO THE LOWER HALF OF THE 40S IN THE 
LOW LYING AREAS...WHILE COASTAL AREAS AND SOME EXPOSED HIGHER 
TERRAIN ARE IN THE LOWER HALF OF THE 50S. 

SYNOPTIC PATTERN/WEATHER EVOLUTION:

THE SFC HIGH GRADUALLY SINKS OFF TO THE SE TODAY...WHILE THE 
SOUTHERLY PRESSURE GRADIENT TIGHTENS AND DRAWS IN MORE LOW LEVEL 
MOISTURE THROUGH THE DAY AND NIGHT. THE INITIAL H8 TROUGH AND 
MOISTURE ADVECTION WILL DRIFT OVERHEAD TODAY...AND MAYBE SOME 
SPRINKLES ARE POSSIBLE EARLY THIS MORNING...BUT DAYTIME MIXING AND 
DRYING OF THE LOWER LEVELS WILL MOST LIKELY SEAL OFF ANY CHANCES FOR 
SPRINKLES TO HIT GROUND. THE MOISTURE WILL REVEAL ITSELF IN A HIGHER 
BASED CUMULUS FIELD...BUT ALSO MAY GET STUCK UNDERNEATH AN INVERSION 
IN FCST BFR SOUNDINGS. THIS COULD LEAD TO A PERIOD OF MOSTLY CLOUDY 
SKIES...BUT REALLY DOUBT THIS WILL HAVE MUCH AFFECT ON RISING TEMPS 
REACHING THE MIDDLE 70S MOST AREAS. THIS INVERSION AND DRY SFC TDS 
RESULT IN A PRETTY PRONOUNCED CAPPING FOR THE ENTIRE DAY...WITH 
LITTLE TO NO CHANCE FOR AFTERNOON CONVECTION. 

THERE ARE DIFFERENCES IN HOW THIS LID EVOLVES OVER THE NIGHT...BUT 
WE WILL AT LEAST BE TRENDING TOWARD MORE UNSTABLE CONDITIONS. SOME 
SHORTWAVE ENERGY/VORTICITY EJECTS FROM AFOREMENTIONED CLOSED LOW 
DRIFTING THROUGH SRN CANADA. THIS FORCING ARRIVES LATE EVENING AND 
OVERNIGHT. WEAK LOW PRESSURE AND A WARM FRONT LIFT UP TOWARD/INTO 
NRN MICHIGAN. THE SAME FCST BFR SOUNDINGS...IN A SCENARIO LIKE 
THIS...WOULD LIKELY ERODE/SUPPRESS THE CAP...UNLIKE THE GFS 
SUGGESTION. RATHER...WILL GO WITH SHOWERS AND EMBEDDED 
GARDEN-VARIETY THUNDERSTORMS DEVELOPING LATE EVENING/OVERNIGHT. 
NOTHING SEVERE ANTICIPATED...AS OUR LAPSE RATES AND OVERALL 
INSTABILITY WILL NOT MIRROR CURRENT ENVIRONMENT ACROSS THE NRN 
PLAINS. WE WILL ONLY HAVE SEVERAL HUNDRED J/KG MUCAPE WITH LAPSE 
RATES ALOFT 6-6.5C/KM. THE GREATEST MUCAPE LIKELY TO BE DOWN AROUND 
THE MANISTEE/CADILLAC AREAS...ALSO WHERE SOME ADDITIONAL LIFT 
ASSISTANCE WILL BE PROVIDED BY UPPER DIVERGENCE IN SOMEWHAT OF A 
DOUBLE JET STRUCTURE. WOULD GO WITH LIKELY CHANCES FOR SEEING 
PRECIPITATION...BUT BULK OF INSTABILITY AND LLJ FORCING WILL ONCE 
AGAIN BE ACROSS SRN WI/NRN IL/SRN LAKE MICHIGAN. THIS COULD BLOCK US 
FROM SEEING SOME OF THE ACTION. REGARDLESS...LIKELY TO BE SOME 
PRECIPITATION...BEST DESCRIPTION OF WHICH CAN BE PROVIDED BY LATER 
SHIFTS AS THE EVENT UNFOLDS.

LOWS TONIGHT WILL LIKELY BE MILD WITH THICKENING CLOUDS...LOWER HALF 
OF THE 60S MOST AREAS. 

&&

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 303 AM EDT FRI JUL 25 2014

...RAINY END TO THE WEEKEND/COOL TEMPERATURES ON THE WAY FOR THE 
START OF NEXT WEEK...

HIGH IMPACT WEATHER POTENTIAL: NOT A BUNCH. CHANCES FOR A FEW 
NON-SEVERE THUNDERSTORMS HEADING THROUGH THE WEEKEND.  

PATTERN SYNOPSIS/ANTICIPATED EVOLUTION: WHILE STILL PLENTY OF THE 
FINER DETAILS TO WORK OUT...MUCH TALKED ABOUT TRANSITION TO A MORE 
MERIDIONAL NOAM UPPER FLOW PATTERN STILL ON TARGET TO DEVELOP HEADING 
INTO AND THROUGH NEXT WEEK. NO LINGERING DOUBT MICHIGAN WILL BE 
CENTERED IN UNSEASONABLY CHILL PRODUCING TROUGH AXIS...WHICH WILL BE 
A SLOW ONE TO DEPART ONCE IT DEVELOPS. PLAYERS FOR SUCH UNUSUAL 
DEVELOPMENTS ALREADY ON THE TABLE...WITH LARGE NORTHERN QUEBEC GYRE 
SIMPLY STUCK IN PLACE...ALL THE WHILE STRONG PACIFIC SHORTWAVE MAKES 
STEADY EAST PROGRESS ACROSS THE SOUTHERN CANADIAN ROCKIES. THE 
LATTER WILL SIMPLY REINFORCE AND EXTEND THE FORMER AS IT 
SLING-SHOTS AROUND IT THROUGH EARLY NEXT WEEK. COMBINE THAT WITH 
DEVELOPMENT OF FULLY MATURE GULF OF ALASKA TROUGH/WEST NOAM RIDGE 
COUPLET (NOT TO MENTION ONE REALLY AMPLIFIED ATLANTIC RIDGE)...AND 
ONE CAN SEE WHY A PATTERN MUCH MORE RESEMBLING THE COOL SEASON IS 
EXPECTED. 

PRIMARY FORECAST CONCERNS/CHALLENGES: TEMPERATURE TRENDS THROUGHOUT 
AND EVOLUTION OF PERIODIC RAIN CHANCES. THUNDERSTORM POTENTIAL AND 
INTENSITY WILL ALSO NEED ADDRESSING THIS WEEKEND.

DETAILS: SATURDAY CONTINUES TO REMAIN A CHALLENGE...WITH TIGHT 
THETA-E GRADIENT AND SURGE OF BEST UPPER JET FORCING EXITING STAGE 
RIGHT RATHER QUICKLY DURING THE MORNING. LEFT BEHIND WILL BE A MUCH 
MORE MOIST LOW LEVEL AIRMASS...WITH DEWPOINTS EXPECTED TO BE UP IN 
THE MID AND PERHAPS UPPER 60S. KINDA EXPECT WHAT EVER PUNCHES 
THROUGH HERE TONIGHT WILL LARGELY EXIT DURING THE MORNING 
HOURS...LEAVING NEXT LOW AMP WAVE AND DIURNAL DRIVEN DESTABILIZATION 
TO DRIVE ADDITIONAL SHOWER AND STORM DEVELOPMENT. MOISTURE CROSS 
SECTIONS SHOW GOOD TO EXCELLENT MOISTURE DEPTH UP THROUGH H7...WITH 
AGGRESSIVE DRYING ABOVE THIS LAYER. MANIPULATING MODEL DERIVED 
SOUNDINGS WITH ANTICIPATED DEWPOINTS/TEMPERATURES DOES YIELD 
DEVELOPMENT OF UPWARDS OF 1K-1.5K J/KG OF ML CAPE DURING THE 
AFTERNOON. THINK THIS MIGHT BE A TOUCH AGGRESSIVE...EXPECTING LOW 
LEVELS TO BE NOT QUITE AS SATURATED AS GUIDANCE WOULD SUGGEST. WHILE 
BEST DYNAMICS WILL HAVE EXITED...NOT ALL IS LOST...WITH MID LEVEL 
JET ROTATING THROUGH THE SOUTHWEST LAKES...COMBINING WITH LAKE 
INDUCED LOW LEVEL CONVERGENCE /PARTICULARLY IN NORTHEAST LOWER AND 
INTERIOR EASTERN UPPER MICHIGAN/ AND SAID WEAK WAVE. ABOVE 
DEFINITELY SUPPORTS SOME ADDITIONAL CONVECTIVE POTENTIAL... 
ESPECIALLY IN CLIMATOLOGICALLY FAVORED AREAS. INHERITED FORECAST 
ALREADY WELL TRENDED IN THIS DIRECTION...WITH ONLY SOME MASSAGING 
NEEDED TO POP/WEATHER GRID. DECENT DEEP LAYER SHEAR OF 30 TO 40 
KNOTS LARGELY OFFSET BY LIMITED MID LEVEL LAPSE RATES AND SKINNY 
CAPE PROFILE UP THROUGH HAIL GROWTH ZONE. SO...IF STORMS CAN DEVELOP 
(A BIG IF)...WOULD EXPECT THEM TO REMAIN BELOW SEVERE LIMITS.

LOSS OF INSTABILITY AND RAPID APPROACH OF SHORTWAVE RIDGING EXPECTED 
TO BRING A MOSTLY DRY SATURDAY NIGHT. RATHER VIGOROUS CURRENT 
SOUTHERN CANADA WAVE QUICKLY FOLLOWS FOR SUNDAY...AND WHEN COMBINED 
WITH GOOD SLUG OF LEFT EXIT REGION UPPER JET DYNAMICS...LOOKS TO 
BRING A RATHER WIDESPREAD SHOWER EVENT SUNDAY INTO SUNDAY NIGHT. 
SYSTEM EVEN LOOKS TO TAKE ON COLD SEASON CHARACTERISTICS...WITH MORE 
STEADY RAIN POTENTIAL IN FAVORED NORTH SIDE DEFORMATION FIELD. SOME 
THUNDER THREAT REMAINS SUNDAY WITH OPPORTUNITY FOR SOME 
DESTABILIZATION BEFORE BETTER FORCING ARRIVES.

TROUGHING DIGS IN AND STAYS THERE-ON-AFTER...PERHAPS LASTING THROUGH 
ALL OF NEXT WEEK. COLDEST ANOMALIES EXPECTED TO SLIDE JUST OFF TO 
OUR NORTHEAST. THAT SAID...COLD AIR ADVECTION ON FRONTSIDE OF 
SPRAWLING NORTHERN PLAINS HIGH WILL BE IMPRESSIVE INDEED...ONCE 
AGAIN NOT ALLOWING TEMPERATURES TO GET OUT OF THE 60S ON MONDAY. A 
VERY SLOW MODERATION TO FOLLOW...WITH HIGHS WARMING A FEW DEGREES 
EACH DAY THROUGH THURSDAY (EVEN BY THURSDAY...HIGHS WILL STILL BE A 
FEW DEGREES BELOW NORMAL). DESPITE TROUGHING...JUST NOT OVERLY 
IMPRESSED WITH RAIN CHANCES AFTER SUNDAY NIGHTS WAVE PASSAGE. DEEP 
LAYER FLOW WILL REMAIN NORTH TO NORTHWEST...AND MID LEVEL 
TEMPERATURE REALLY NEVER GET TOO COLD...REACHING THE NEGATIVE UPPER 
TEENS AT H5 LATER MONDAY INTO TUESDAY. OF COURSE...ANY WAVES 
ROTATING THROUGH WILL ONLY HELP THE SHOWER CAUSE...BUT TIMING AND 
MAGNITUDE OF SUCH NOT POSSIBLE TO DETERMINE JUST YET. NO REASON TO 
CHANGE THAT WHICH WAS INHERITED...FEATURING JUST ISOLATED/LOW CHANCE 
SHOWER POTENTIAL DURING THE DAYTIME HOURS. THIS WILL CHANGE...OF 
COURSE...BUT PLENTY OF TIME TO FIGURE THOSE DETAILS OUT IN THE 
COMING DAYS. 

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 136 AM EDT FRI JUL 25 2014

VFR CONDITIONS ARE EXPECTED AT ALL NRN LWR MICHIGAN TAF SITES THRU 
FRIDAY NIGHT. SCT CU AND INCREASING MID CLOUDS ON FRIDAY WILL LEND 
TO PARTLY TO MOSTLY CLOUDY SKIES. CHANCES OF SHOWERS AND 
THUNDERSTORMS WILL BEGIN TO INCREASE AFTER 00Z SATURDAY AHEAD OF A 
WEAK COOL FRONT...BUT CHANCES ARE TOO SMALL TO INCLUDE IN THE TAF AT 
THIS POINT. LIGHT/VARIABLE WINDS OVERNIGHT INTO THE MORNING HOURS 
WILL BECOME S/SW AT AROUND 10 KTS BY LATE MORNING.

&&

.MARINE...
ISSUED AT 303 AM EDT FRI JUL 25 2014

SW WINDS WILL INCREASE HEADING THROUGH TONIGHT...AHEAD OF SFC LOW 
PRESSURE AND A WARM FRONT...WHICH WILL BRING AREAS OF SHOWERS AND 
GARDEN-VARIETY STORMS TO THE GREAT LAKES. NOTHING SEVERE....AND 
WINDS TO REMAIN ABOVE ADVISORY LEVELS. EXPECTING NO MORE THAN 
20KTS..WHICH WILL LARGELY RESIDE ACROSS LAKE MICHIGAN. WINDS REMAIN 
UNDER ADVISORY LEVELS SATURDAY AND SUNDAY IN WEAK GRADIENT. ANOTHER 
SFC LOW CROSSES SUNDAY MORNING WITH A BETTER CHANCE FOR SHOWERS AND 
STORMS...AND MUCH COOLER AIR SET TO ARRIVE THROUGH THE DAY SUNDAY 
AND SUNDAY NIGHT. 

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.

&&

$$

SYNOPSIS...MSB
SHORT TERM...SMD
LONG TERM...MSB
AVIATION...MR
MARINE...SMD