Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPHI 251956 AFDPHI AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 356 PM EDT FRI JUL 25 2014 .SYNOPSIS...
-- Changed Discussion --
SURFACE HIGH PRESSURE, OVERHEAD, WILL MOVE OFFSHORE ON SATURDAY SETTING UP A RETURN FLOW. A WARM FRONT CROSSES THE REGION LATE ON SATURDAY WHILE THE PARENT LOW PRESSURE SYSTEM MOVES THROUGH THE GREAT LAKES. THE ATTENDANT COLD FRONT SWINGS THROUGH LATE ON SUNDAY INTO MONDAY FOLLOWED BY ANOTHER HIGH PRESSURE SYSTEM.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
-- Changed Discussion --
THE WRF-NMMB INITIALIZATION DID LOOK BETTER THAN THE GFS AT 500MB, ESPECIALLY UPSTREAM. AT 850MB AND 925MB IT WAS A MIXED BAG BETWEEN THE MODELS, BUT NEARLY ALL ERRORS THAT THERE WERE, WERE 1C. NO BIG CHANGES IN THE MODELS DP/DT FROM YESTERDAY. THE BEST OF THIS AIR MASS IS NOW BEHIND US. A POCKET OF HIGHER DEW POINTS AT 850MB OVER NJ CORRESPONDED TO THE CONVECTIVE TEMP BEING REACHED. JUST LOOKING AT HOW THE CU FIELD IS ALREADY GASPING SHOWS HOW LONG IT WILL LAST (NOT AT ALL) INTO THIS EVENING. TONIGHT IS A FLIP OF LAST NIGHT AS THE EVENING SHOULD BE THE CLEARER HALF BEFORE HIGH CLOUDS FROM THE FORMER AND ONGOING MCS IN THE MIDWEST WORK THEIR WAY INTO OUR CWA OVERNIGHT. THE WRF-NMMB ESPECIALLY AND THE GFS SOMEWHAT ALSO TAKE SOME OF THE LOWER LEVEL MOISTURE IN SOUTHWEST VIRGINIA AND ADVECT IT INTO OUR CWA LATE TONIGHT. DONT SEE MUCH OMEGA AT THAT LEVEL, SO EMPHASIS REMAINS MORE WITH THE HIGH CLOUDS. THAT BEING SAID, WE HAD TEMPS DROP OVERNIGHT IN THE MORE TRADITIONAL TYPICAL FASHION. DEW POINT ERRORS TODAY HAVE BEEN TOO LOW AND THEY ARE RISING TO THE LEE OF THE SEA BREEZE FRONT. SO WE DID NOT BUY INTO THE LOWER RADIATIONAL COOLING MINS ON STAT GUIDANCE FOR THIS REASON.
-- End Changed Discussion --
&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
-- Changed Discussion --
CONFIDENCE IS NOT HIGH IN EITHER DIRECTION ABOUT CONVECTION AND THE END RESULT FOR NOW IS A RATHER GENERIC VANILLA SUMMER`S DAY FORECAST FOR SATURDAY. THE MODELS HAVE BEEN PRETTY CONSISTENT IN POOLING DEW POINTS AS SATURDAY PROGRESSES IN OUR CWA. PARTLY BECAUSE OF THE AFOREMENTIONED SHORT WAVES AND ALSO LOOKS TO BE SOME SFC WIND CONVERGENCE. THEY ACTUAL SPIKE UPWARD HAS BECOME MORE LOGICAL FROM YESTERDAY WHERE SOME OF THE MODEL FCST SFC DEW POINTS WERE REACHING THE MID 70S. STILL MOS GUIDANCE IS FORECASTING DEW POINTS 5 TO 10F LOWER THAN THEIR OWN MODEL GUIDANCE. THIS PLUS TEETERING CLOSE TO THE EDGE OF THE AVAILABLE CAPE FOR THUNDER AND WHETHER OR NOT THE CAP WOULD HOLD. GIVEN THE SHORT WAVES ALOFT, THINKING THE CAP WONT. THIS LEAVES THE DEW POINTS. IF THEY DONT GET INTO THE MID 60S ALONG THE COASTAL PLAIN, CHANCES ARE THERE WONT BE ENOUGH CAPE. NORTH AND WEST THERE IS ALWAYS THE OROGRAPHIC INFLUENCE THAT MAY COMPENSATE FOR LOWER DEW POINTS. MODIFIED SOUNDING CONVECTIVE TEMPS ARE PREDICTED TO BE REACHED, SO WE DID EXPAND THE MENTION OF DURING THE AFTERNOON THUNDER GEOGRAPHICALLY. CONVERSELY SINCE MOST MESOSCALE MODELS ARE CONVERGING SOUTH AND EAST TOWARD THE HIGHER DEW POINT POOLING, WE DID LOWER POPS IN THE NORTHWEST PART OF OUR CWA. PREDICTED 1395 1000-850MB THICKNESSES ARE NOT BUYING MAX TEMPS AS HIGH AS THEY HAVE DONE IN PAST SUMMERS. FULL SUN MACROS LOOK OVERCOOKED AND MAX TEMPS WERE KEPT CLOSER TO 10-11C OVER PREDICTED 925MB TEMPS. THIS IS CLOSE TO STAT GUIDANCE AND CONTINUITY. GFS THERMAL GUIDANCE WENT DOWN ABOUT 1-2C FROM THURSDAY`S LEVELS AOB 850MB.
-- End Changed Discussion --
&& .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
-- Changed Discussion --
SUNDAY...A DECAYING MCS SHOULD BE DIVING WELL TO THE SOUTHWEST OF OUR REGION AS ONE MID-LEVEL SHORTWAVE CRUISES THROUGH. SURFACE WARM FRONT SHOULD BE LIFTING THROUGH DURING THE EARLY PART OF THE MORNING. MOISTURE WILL CONTINUE TO INCREASE WITH A SOUTHWEST SURFACE FLOW WITH PWATS EXCEEDING 1.5 INCHES. EARLY MORNING SHOWERS AND THUNDERSTORMS SHOULD BE WANING BY LATE MORNING AS MOST OF THE OPERATIONAL GUIDANCE SHOWS THE REGION BREAKING OUT. NOT QUITE SURE HOW LONG LIVED THE BREAK WILL BE AS CONVECTIVE TEMPERATURES SHOULD EASILY BE MET AS HIGHS APPROACH 90F SO WE CONTINUE WITH CHANCE POPS. BETTER FORCING MOVES IN ALOFT WITH A MUCH STRONGER SHORTWAVE AND APPROACHING COLD FRONT LATER ON SUNDAY. BETTER HEIGHT FALLS, SHEAR PROFILES AND LESS CAPPING SHOULD ALLOW FOR MUCH MORE ORGANIZED CONVECTION TO OCCUR. SPC HAS US IN DAY 3 OUTLOOK AT THIS TIME SO WILL CONTINUE WITH THE HWO HIGHLIGHTING. MONDAY...COLD FRONT WILL CONTINUE TO MOVE THROUGH THE REGION, THOUGH NOT AT A BLISTERING PACE. WEAK SURFACE CYCLOGENESIS IS POSSIBLE ON MONDAY AS THE FRONT SITS JUST TO OUR EAST SO WE KEEP CHANCE POPS IN PLACE DURING THE DAY. TEMPERATURES SHOULD END UP BEING AROUND AVERAGE ACROSS THE EAST AND SLIGHTLY BELOW ACROSS THE WEST. TUESDAY - THURSDAY...DRYING TREND SHOULD COMMENCES ACROSS A MAJORITY OF THE REGION, BUT WITH THE MID-LEVEL TROUGH/COLD POOL ALOFT, AND THE SLIGHTEST HINT OF INSTABILITY AROUND, ISOLATED SHOWERS ARE POSSIBLE ON TUESDAY...BETTER FURTHER NORTH. THE CHANCES FOR SHOWERS DECREASES EACH AFTERNOON THEREAFTER. TEMPERATURES SHOULD END UP BEING BELOW NORMAL FOR LATE JULY STANDARDS.
-- End Changed Discussion --
&& .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. 18Z TAFS CONTINUED VFR FORECAST. REST OF THIS AFTERNOON FEW TO SCATTERED VFR CUMULUS WITH THE GREATEST CONCENTRATION AT NJ TERMINALS AND AIRPORTS. A SEA AND BAY BREEZE FRONTS HAVE FORMED. THE SEA BREEZE FRONT HAS MADE DECENT PROGRESS AND IS ALREADY FROM BRIDGETON TO HAMMONTON TO JACKSON AND MIDDLETOWN IN NJ. THE BAY BREEZE IS HARDER TO DISCERN. THIS FRONT SHOULD CONTINUE TO MOVE NORTHWEST WITH A WEAKENED VERSION PREDICTED TO GET TO THE KPHL AREA AIRPORTS BETWEEN 23Z AND 00Z. WIND SPEEDS EVEN BEHIND THE FRONT SHOULD BE 10 KNOTS OR LESS. PRECEDING THE FRONT AND AT OTHER TERMINALS LIGHT WEST TO SOUTHWEST WINDS WILL PREVAIL. FOR TONIGHT WINDS WILL BECOME LIGHT AND VARIABLE, SOUTHWEST IF THERE IS A DIRECTION. THE CIRRUS IN THE TAFS IS MORE FOR THE SECOND HALF OF THE NIGHT. NO FOG IS EXPECTED TO FORM. ON SATURDAY. VFR CIG EXPECTED. MOST OF THE REMAINING TAF TIME IT SHOULD BE AT THE ALTOCU LEVEL. SOUTHWEST WINDS WILL BE INCREASING AS THE MORNING PROGRESS. WINDS IN THE LAST FORECAST GROUP REPRESENT MORE OF THE LATTER HALF OF THE MORNING/EARLY AFTERNOON EXPECTATIONS. ISOLATED SHOWERS AND THUNDERSTORMS SHOULD OCCUR, BUT COVERAGE FOR NOW APPEARS TOO SMALL AND LIKELY AFTER 18Z TO INCLUDE IN ANY TERMINALS. CONFIDENCE TOO LOW FOR KPHL INCLUSION. OUTLOOK... SUNDAY - MONDAY...SUB-VFR CONDITIONS EXPECTED IN AREAS OF SHOWERS AND THUNDERSTORMS. TUESDAY - WEDNESDAY...VFR.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
SEA AND BAY BREEZE FLOW SHOULD DOMINATE THE NEARSHORE AND DELAWARE BAY WATERS INTO THIS EVENING BEFORE WINDS BECOMING LIGHTER OVERNIGHT. THE HIGH PRESSURE SYSTEM WILL BE MOVING OFFSHORE AND A SLIGHTLY STRONGER SYNOPTIC SCALE RETURN FLOW IS PREDICTED FOR SATURDAY. AS IS TYPICALLY THE CASE, MODEL GUIDANCE OVER THE WATERS IS NORMALLY OVERDONE IN CASES LIKE THIS AND WINDS AND SEAS WERE KEPT BELOW SCA CRITERIA THRU THE DAY ON SATURDAY. OUTLOOK... SUNDAY...SUB-SCA EXPECTED WITH SCATTERED SHOWERS AND THUNDERSTORMS. MONDAY...SEAS MAY BUILD TO SCA LEVELS UNDER A STRENGTHENING SOUTHWEST SURFACE FLOW. TUESDAY - WEDNESDAY...SUB-SCA CONDITIONS EXPECTED.
-- End Changed Discussion --
&& .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...HEAVENER NEAR TERM...GIGI SHORT TERM...GIGI LONG TERM...HEAVENER AVIATION...GIGI/HEAVENER MARINE...GIGI/HEAVENER

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.