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Area Forecast Discussion

000
FXUS63 KAPX 291816
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
216 PM EDT FRI AUG 29 2014

.SYNOPSIS...
ISSUED AT 300 AM EDT FRI AUG 29 2014

HIGH PRESSURE WILL SLIDE INTO NEW ENGLAND TODAY...ENDING UP OFF
THE EAST COAST THIS WEEKEND. MEANWHILE...SLOW MOVING LOW PRESSURE
WILL TRACK FROM THE CENTRAL PLAINS INTO THE GREAT LAKES BY
SATURDAY. THIS PATTERN WILL DELIVER A COUPLE ROUNDS OF RAIN AND
PERHAPS A FEW THUNDERSTORMS TODAY INTO SATURDAY...WITH A BRIEF
BREAK EXPECTED ON SUNDAY AS HIGH PRESSURE RETURNS. CHANCES FOR
SHOWERS AND THUNDERSTORMS WILL RETURN ON LABOR DAY...AS A COLD
FRONT MARCHES THROUGH THE REGION.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 300 AM EDT FRI AUG 29 2014

...INCREASING RAIN CHANCES AND A FEW THUNDERSTORMS...

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

CURRENT WEATHER AND SYNOPTIC PATTERN:

UPPER FLOW IS SPLIT UPSTREAM WITH MORE ZONAL FLOW RIPPING THROUGH 
CANADA...AND A SHORTWAVE TROUGH AND ASSOCIATED SFC LOW IN THE 
CENTRAL PLAINS. A WARM FRONT EXTENDS ACROSS IA/IL WHERE DEEP LOW 
LEVEL MOISTURE...PWATS TO 2.00" AND UNIMPRESSIVE 6.0 C/KM MID LEVEL 
LAPSE RATES RESIDED. LOW LEVEL WARM ADVECTION WITH AN H8 LLJ OF 
30KTS WAS FEEDING MOISTURE UP INTO THE MID AND UPPER MISSISSIPPI 
VALLEY...AND IN TANDEM WITH THE ELEVATED WARM FRONT AND INITIAL 
VORTICITY EJECTED FROM THE TROUGH. THIS HAS RESULTED IN A THICKENING 
OF MID AND UPPER LEVEL CLOUDS IN OUR REGION...AND SOME WEAK RETURNS 
ON AREA RADARS AS WELL AS SOME ENCROACHING ON US. THE LOW LEVELS 
WERE STILL RATHER DRY HERE...AND MUCH OF THIS PRECIPITATION WAS 
EVAPORATING BEFORE REACHING GROUND. THE HEAVIER RAINFALL AND 
THUNDERSTORMS WERE WELL WEST AND SOUTH...CLOSER TO THE SFC/UPPER 
LOWS...WARM FRONT AND BETTER FORCING.  

SYNOPTIC PATTERN/WEATHER EVOLUTION:

THE FASTER FLOW ALOFT WILL REMAIN TO OUR NORTH ACROSS CANADA...IN 
WHICH A BROAD SHALLOW WAVE WILL DRAW A VERY SHALLOW COLD FRONT OVER 
INTO EASTERN UPPER/WISCONSIN. AT THE SAME TIME...THE SHORTWAVE 
TROUGH WILL SLOWLY LIFT NE AND INTO THE WESTERN GREAT LAKES BY LATE 
TONIGHT...AND IT'S ASSOCIATED SFC LOW WILL RIDE ALONG THE FRONT 
THROUGH WISCONSIN. THIS IS FURTHER WEST THAN ORIGINALLY 
ANTICIPATED.

PUTTING IT ALL TOGETHER...THE INITIAL EJECTED ENERGY WEAKENS AS IT 
RUNS INTO OUR RIDGE...WHILE WE CONTINUE TO DEEPEN MOISTURE AND CLOUD 
UP THIS MORNING. FORCING IS VERY WEAK...AND CAN FORESEE SOME VERY 
LIGHT RAIN SHOWERS OR SPRINKLES THIS MORNING FOR MUCH OF NRN 
MICHIGAN. MAYBE SOME MORE ORGANIZED RAINS ACROSS EASTERN UPPER...THE 
STRAITS AND NEARER LAKE MI...WHERE H8 LLJ FORCING IS STRONGER AND 
WITHIN THE BETTER MID LEVEL FLOW AND VORTICITY ADVECTION. ONCE THE 
AXIS OF DEEPER MOISTURE/GRADIENT LIFTS NE BY 18Z OR SO...WE ARE MORE 
HUMID BUT THERE IS A LACK OF FORCING THROUGH THIS EVENING. MOST 
LIKELY...THERE WILL NOT BE MUCH GOING ON. WITH PWATS STILL 1.5" OR 
HIGHER THOUGH...IT WON'T TAKE MUCH TO IGNITE A SHOWER. THE BETTER 
RAINFALL IS LIKELY NOT COMING UNTIL LATE TONIGHT AS THE SYNOPTIC
FEATURES ARRIVE...THE SHORTWAVE AND SFC LOW. BETTER ORGANIZATION
OF THE LLJ AND THETA-E ADVECTION SHOULD RESULT IN THE BEST FORCING
AND GROWING INSTABILITY (SEVERAL HUNDRED J/KG MUCAPE) FOR SHOWERS
AND STORMS. TOTAL QPF FOR MOST WILL NOT COME ANYWHERE CLOSE TO
SOMETHING "HEAVY"...AT LEAST THROUGH THIS EVENING. AGAIN...THE
BEST CHANCE FOR ANY SORT OF HEAVIER RAINFALL WILL BE OFF TO OUR
NW...POSSIBLY SNAKING ACROSS WESTERN CHIP/MACK COUNTIES OF EASTERN
UPPER...CLOSER TO THE FRONTAL ZONE.

CLOUDY THIS MORNING WITH MAYBE SOME THINNING OF THE CLOUDS THIS 
AFTERNOON...HIGHS IN THE MIDDLE TO UPPER 60S EASTERN UPPER...TO THE 
LOWER AND MIDDLE 70S NRN LOWER. 

LOWS TONIGHT...MILD...WITH A GOOD DEAL OF CLOUDS AND INCREASED BL 
WINDS...IN THE 60S ALL AREAS. 

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 300 AM EDT FRI AUG 29 2014

...A WET SENDOFF TO METEOROLOGICAL SUMMER...

HIGH IMPACT WEATHER POTENTIAL: SEVERAL CHANCES FOR THUNDERSTORMS...
PRIMARILY SATURDAY AND AGAIN FOR LABOR DAY ITSELF...WITH A SMALL 
LOCALIZED HEAVY RAIN THREAT...PARTICULARLY ACROSS NORTHWEST LOWER 
AND EASTERN UPPER MICHIGAN.

PATTERN SUMMARY: A RATHER HEALTHY SEMI-CLOSED UPPER LEVEL TROUGH 
WILL MEANDER FROM THE CENTRAL PLAINS TODAY INTO THE NORTHERN GREAT 
LAKES SATURDAY NIGHT...FORCING AN ELEVATED WARM FRONT THROUGH THE 
REGION TODAY...OPENING THE GATES TO A MUCH MORE MOISTURE-LADEN 
AIRMASS THROUGH THE DAY ON SATURDAY. A WEAK SURFACE LOW AND 
ASSOCIATED COLD FRONT IS EXPECTED TO ARRIVE HERE LATE SATURDAY 
AFTERNOON OR EVENING...WITH HIGH PRESSURE TAKING OVER FOR THE DAY ON 
SUNDAY. HANG TIGHT THOUGH...AS ANOTHER STRONGER UPPER TROUGH AND 
ASSOCIATED COLD FRONT WILL BE KNOCKING ON THE DOOR BY LABOR 
DAY...USHERING IN A FAST ZONAL FLOW REGIME ACROSS MUCH OF THE 
COUNTRY FOR THE MAJORITY OF NEXT WEEK.

A LOOK AT THE FORECAST DETAILS...

SATURDAY: WEAKENING UPPER TROUGH WILL BE MAKING ITS APPROACH THROUGH 
THE DAY...AS OUR AIRMASS REMAINS VERY SOUPY WITH PWAT VALUES PUSHING 
1.75 INCHES (UP AROUND 2.5 SD ABOVE NORMAL AND NEARING THE 99TH 
PERCENTILE BY CLIMO STANDARDS). REALLY GETTING THE FEELING THAT THE 
MAJORITY OF THE HEAVY RAIN THREAT WILL EXIST FRIDAY NIGHT AS 
TIGHTENING MID LEVEL THERMAL REGIME FORCES A DYNAMIC JET RESPONSE 
OVER THE WESTERN LAKES...SUCH THAT MUCH OF THE WESTERN CWA GETS IN 
ON SOME MODEST UPPER JET DIVERGENCE TO HELP ENHANCE A TRAINING 
CONVECTIVE THREAT GIVEN STRONGLY PARALLEL DEEP LAYER WIND FIELDS TO 
THE FORCING BOUNDARY JUST TO OUR WEST. THAT WHOLE SETUP LOOKS LIKE 
IT WILL BREAK DOWN BY SATURDAY MORNING AS THE UPPER JET CORE SLIPS 
OVERHEAD...LEAVING THE SYNOPTIC FORCING COMPONENT TO A BETTER PUSH 
OF DPVA...ALSO HELPED ALONG TO A SMALL DEGREE TO WEAK LOWER LEVEL 
FRONTAL CONVERGENCE.

HAVE LITTLE DOUBT THAT ALL AREAS WILL END UP WITH MEASURABLE RAINS 
AT SOME POINT THROUGH THE DAY...AND GOING CATEGORICAL POPS ARE MORE 
THAN WARRANTED. HOWEVER...THE SETUP LOOKS LIKE IT WILL FAVOR MORE OF 
A MORNING COMPONENT FOR WESTERN AREAS...WITH RAIN CHANCES TRANSITING 
EASTWARD THROUGH THE AFTERNOON WHERE A MORE CONVECTIVE COMPONENT MAY 
BE REALIZED PROVIDED WE CAN REALIZE SOME SNEAKY WARMER TEMPS OUT 
THAT WAY (WHICH APPEARS DOABLE). TEMPS WARMING THROUGH THE 70S 
COMBINED WITH DEW POINTS RISING THROUGH THE 60S (MAYBE LOWER 70S) 
WOULD SUPPORT MLCAPE VALUES PUSHING 1200 J/KG...SO A THUNDER MENTION 
IS MORE THAN JUSTIFIED...ESPECIALLY EAST OF I-75. SEVERE THREAT 
LOOKS LOW BUT WITH A WARM FRONT/WEAKLY BACKED FLOW NEARBY AND 
STRENGTHENING FLOW ALOFT INTO THE AFTERNOON...WOULDN'T BE SHOCKED TO 
SEE A FEW SNEAKY STRONGER STORMS...AGAIN PROVIDED WE CAN REALIZE 
ENOUGH INSTABILITY. 

SATURDAY NIGHT-SUNDAY NIGHT: ELONGATING WEAK DEFORMATION AXIS WITH 
THE UPPER TROUGH SHEARING OUT ALOFT SHOULD PROVIDE A CONTINUED 
THREAT FOR SHOWERS INTO MUCH OF SATURDAY NIGHT...ENDING WITH TIME AS 
SLIGHTLY DRIER AIR WORKS INTO THE PICTURE AND UPPER SUPPORT WANES. 
HOWEVER...WILL HAVE TO WATCH THE POSSIBILITY FOR ANOTHER COMPACT 
SHORTWAVE TO CROSS THE AREA ON SUNDAY...AS INCREASINGLY HINTED AT BY 
00Z GUIDANCE TRENDS. THAT FEATURE...COMBINED WITH A REMNANT SOUPY 
AIRMASS DOWN LOW WHILE DRYING OCCURS ABOVE 850MB...SUGGESTS WE MAY 
BE STUCK WITH SOME STUBBORN STRATUS AND MAYBE EVEN A LITTLE DRIZZLE 
LATE SATURDAY NIGHT INTO PART OF (MAYBE EVEN MUCH OF) SUNDAY. SHOULD 
THAT NEW FEATURE ACTUALLY COME TO FRUITION...A DIURNAL SHOWER THREAT 
MAY BE REALIZED CLOSER TO SAGINAW BAY BUT THE BETTER CHANCES LOOK TO 
BE ACROSS SOUTHEAST LOWER...WITH CONFIDENCE LOW ENOUGH IN SEEING 
ENOUGH SUNSHINE TO BOOST INSTABILITY TO MAINTAIN A DRY FORECAST FOR 
MUCH OF SUNDAY. CLOUD POTENTIAL ALSO MAKES FOR A TRICKY TEMPERATURE 
FORECAST...BUT HAVE TO BELIEVE WE CAN MUSTER SOME AFTERNOON SUNSHINE 
FOR MANY AREAS AS A QUICK ARRIVING SLUG OF MUCH DRIER AIR IS PROGGED 
TO ROLL IN THROUGH THE DAY. AS SUCH...GOING HIGHS RIGHT ABOUT CLIMO 
LOOK AS GOOD A GUESS AS ANY.

MONDAY (LABOR DAY)-MONDAY NIGHT: ANOTHER PERIOD OF INTEREST GIVEN 
LOTS OF ONGOING OUTDOOR ACTIVITIES AS WE BID A FOND FAREWELL TO YET 
ANOTHER SUMMER SEASON. TIMING WILL BE EVERYTHING WHEN IT COMES TO 
THE BIG EVENT (MACKINAC BRIDGE WALK 2014)...BUT THE BASIC GIST IS 
FOR THE APPROACH OF ANOTHER SHARP UPPER TROUGH THROUGH THE WESTERN 
LAKES...AS A FAIRLY STRONG COLD FRONT GETS PUSHED TOWARD THE AREA BY 
LATE AFTERNOON. FROM A PATTERN RECOGNITION STANDPOINT...THIS ONE 
AGAIN LOOKS TO STAND A HIGH CHANCE OF PRODUCING RAIN ACROSS MOST OF 
THE AREA...AND AT THIS RANGE...LIKELY POPS ARE A GOOD WAY TO HANDLE 
IT. HOWEVER...THERE ARE TIMING DIFFERENCES AMONG THE GUIDANCE...WITH 
A CONSENSUS BLEND SUPPORTING A FRONTAL PASSAGE THROUGH LATE 
AFTERNOON. ANOTHER SURGE OF WARMTH/MOISTURE AHEAD OF THE FRONT 
COMBINED WITH INCREASINGLY STRONG WIND FIELDS BLEEDING OUT JUST 
AHEAD OF THE FRONT RAISE AN EYEBROW FROM A SEVERE STORM 
PERSPECTIVE...AND INDEED THIS ONE BEARS WATCHING OVER THE NEXT FEW 
DAYS. SHARP DRYING BEHIND THE FRONT MONDAY NIGHT SHOULD BRING A 
QUICK END TO PRECIP CHANCES BY 06Z...WITH ANOTHER SHOT OF COOLER AIR 
BEGINNING ITS ARRIVAL.

TUESDAY-THURSDAY: A PERIOD OF MUCH QUIETER WEATHER APPEARS ON TAP AS 
WE HEAD INTO MIDWEEK AND SETTLE INTO THE FIRST FEW DAYS OF 
METEOROLOGICAL AUTUMN. HIGH PRESSURE AND A COOLER/DRYER CANADIAN 
AIRMASS SHOULD DELIVER A NICE DAY FOR BACK TO SCHOOL TUESDAY...WITH 
SIMILAR CONDITIONS ANTICIPATED INTO WEDNESDAY AS WELL...THOUGH 
LIKELY WITH SOME THICKENING CLOUDS. AFTER THAT...CONFIDENCE REALLY 
DECREASES TOWARD LATE WEEK WITH REGARD TO ADDITIONAL CHANCES FOR 
RAIN. ONE THING DOES APPEAR CERTAIN...WE ARE HEADING INTO A FASTER 
NORTHERN TIER ZONAL FLOW REGIME NOT REALLY SEEN AT ALL THIS SUMMER. 
THAT SETUP...COMBINED WITH WHAT SHOULD BE A RATHER TIGHT TEMPERATURE 
GRADIENT ALOFT NEARBY AND A STRONG LIKELIHOOD FOR SEVERAL SHORTWAVES 
WORKING THROUGH THE FLOW...SHOULD SUPPORT A COUPLE RAIN CHANCES 
TOWARD LATE WEEK. TIMING THOSE WAVES AND INDIVIDUAL RAIN CHANCES IS 
IMPOSSIBLE AT THIS RANGE...BUT A LOW CHANCE POP APPEARS WARRANTED BY 
THURSDAY. 

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 205 PM EDT FRI AUG 29 2014

...MOSTLY VFR TO START THEN TRENDING TOWARD MVFR...

LOW CONFIDENCE FORECAST ON THE DETAILS. GENERAL THEME IS A WARM
AND MOIST SOUTHERLY FLOW WILL BE IN PLACE THROUGH THE TAF PERIOD.
MEANWHILE... A TROUGH WILL LIFT NORTHWARD OUT OF THE CENTRAL
PLAINS INTO THE WESTERN GREAT LAKES. THEREFORE...THERE WILL BE
CHANCES FOR MAINLY SHOWERS...THOUGH A THUNDERSTORM OR TWO IS ALSO
POSSIBLE THROUGH EARLY TONIGHT. AS THE TROUGH GETS CLOSER LATER
TONIGHT AND ESPECIALLY SATURDAY MORNING...MORE WIDESPREAD SHOWERS
AND EMBEDDED THUNDERSTORMS ARE EXPECTED. FOG IS ALSO A PRETTY GOOD 
POSSIBILITY TONIGHT ESPECIALLY WITH THE RAIN THAT FELL TODAY.
CIGS/VSBYS SHOULD START OUT VFR BUT LIKELY WILL FALL TO MVFR AND
POSSIBLY EVEN LOWER LATER TONIGHT IN THE EXPECTED FOG FORMATION.

&&

.MARINE...
ISSUED AT 300 AM EDT FRI AUG 29 2014

HIGH PRESSURE IS EXITING EAST WITH THE DEVELOPMENT OF A SOUTHERLY 
WIND...WHICH INCREASES TODAY AND TONIGHT AS THE PRESSURE GRADIENT 
TIGHTENS WITH THE APPROACH OF A WARM FRONT. ADVISORY LEVEL WINDS ARE 
POSSIBLE ACROSS WHITEFISH BAY AND PORTIONS OF LAKE MICHIGAN DUE TO 
AREAS OF COASTAL CONVERGENCE. HOWEVER...INCREASING STABILITY WILL 
LIKELY KEEP STRONGEST WINDS AT 20KTS. MAY EVENTUALLY NEED SOME 
ADVISORIES...BUT NONE PLANNED ATTM. MORE VARIABLE AND LIGHTER WINDS 
ARRIVE SATURDAY AND SATURDAY NIGHT WITH THE PASSAGE OF LOW PRESSURE. 
THE SRLY WIND INCREASES ONCE AGAIN MONDAY WITH A COLD FRONT PLANNED 
TO PASS THROUGH.  

PERIODS OF RAIN AND SOME EMBEDDED THUNDERSTORMS BEGIN TODAY...BUT 
ARE MOST LIKELY TONIGHT INTO SATURDAY EVENING. NO SEVERE WEATHER IS 
ANTICIPATED.

&&

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

&&

$$

SYNOPSIS...LAWRENCE
SHORT TERM...SMD
LONG TERM...LAWRENCE
AVIATION...AS
MARINE...SMD