National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KGRB 302036
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
336 PM CDT WED JUL 30 2014

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 336 PM CDT WED JUL 30 2014

CHANCES FOR AND TIMING OF SHOWERS AND THUNDERSTORMS ARE THE MAIN
CONCERNS THROUGH THURSDAY.

GENERAL SURFACE FLOW ACROSS WISCONSIN WAS RATHER WEAK THIS
AFTERNOON...BUT THERE WAS A WIND SHIFT ACROSS THE NORTHWEST PART
OF THE STATE. BEHIND THE WIND SHIFT NORTHWEST WINDS PREVAILED WITH
SOME GUSTS AROUND 20 KNOTS PRODUCING MORE SIGNIFICANT SURFACE
CONVERGENCE. AN UPPER LEVEL SHORT WAVE WAS MOVING INTO THE REGION
FROM WESTERN ONTARIO AND THERE WERE SOME SHOWERS AND THUNDERSTORMS
AHEAD OF IT THIS AFTERNOON...FROM NORTHERN MINNESOTA AND UPPER
MICHIGAN...INTO NORTHWEST WISCONSIN. LOCAL MESOANALYSIS INDICATED
AROUND 250J/KG MUCAPE AND LITTLE/NO CIN ACROSS NORTH CENTRAL
WISCONSIN BUT NO CAPE FOR THE REST OF THE AREA AS OF 19Z.
HOWEVER...SURFACE TO 1.5KM LAPSE RATES WERE AT LEAST 10K/KM AND 0
TO 3KM LAPSE RATES WERE IN EXCESS OF 7K/KM. MID LEVEL INSTABILITY
WAS UNIMPRESSIVE.

12Z NAM AND GFS AND 00Z ECMWF KEPT SOME QPF IN THE STATE INTO AT
LEAST THE MORNING HOURS ON THURSDAY...BUT THE 12Z EC SEEMED TO BE
MORE IN LINE WITH WHAT IS ACTUALLY OCCURRING. AS A RESULT OF
THIS...HAVE GONE WITH CHANCES FOR SHOWERS AND THUNDERSTORMS LATE
THIS AFTERNOON INTO EARLY EVENING...TAPERING OFF OVERNIGHT. LIGHT
WINDS AND LITTLE CLOUD COVER WILL LIKELY RESULT IN PATCHY FOG
TOWARD MORNING. HAVE THEN BROUGHT POPS BACK INTO THE FORECAST FOR
THURSDAY AFTERNOON.

MADE ONLY MINOR CHANGES TO TEMPERATURES...MAINLY BLENDED THE PREVIOUS
FORECAST WITH SOME OF THE BEST PERFORMING MODEL GUIDANCE.

.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 336 PM CDT WED JUL 30 2014

PRECIPITATION THURSDAY NIGHT INTO SATURDAY WILL PRIMARILY BE
DIURNALLY DRIVEN IN THE WEAKENING CYCLONIC FLOW ALOFT. WHILE SHORT
WAVE TIMING WILL BE DIFFICULT...WILL FOCUS BEST POP TRENDS WITH
THE H500 TEMP PROGS. TEMPS SLIGHTLY MODIFY THURSDAY EVENING
HOWEVER ALL PROGS IN AGREEMENT WITH COOLER H5 TEMPS FOR LATE
THURSDAY NIGHT INTO FRIDAY BEFORE MODIFYING AGAIN FOR LATE FRIDAY
NIGHT INTO SATURDAY. PROGS ALSO INDICATE A SHORT WAVE TROUGH
SLIDING THROUGH ON FRIDAY WITH THE COLDER AIR. WILL KEEP THE
HIGHER END CHC POPS FOCUSED FOR FRIDAY...AND LIGHTER DIURNAL LOWER
END CHC POPS OR DRY ELSEWHERE.

UPPER PATTERN BEGINS TO CHANGE THIS WEEKEND AS THE UPPER LOW
WEAKENS AND LIFTS NORTHEASTWARD AND THE WESTERN STATES RIDGE
BREAKS DOWN TO SOME DEGREE. MODELS ATTEMPTS TO TRACK A SHORT WAVE
OVER THE RIDGE THIS WEEKEND...THEN SLOWLY DROP THIS WAVE AND A
FRONTAL SYSTEM INTO THE WESTERN GREAT LAKES REGION LATER SUNDAY
INTO MONDAY. THE FRONT SLOWS DOWN OR STALLS NEXT WEEK IN THE LESS
AMPLITUDE FLOW AND WILL BE A FOCUS OF CONVECTION. AT THIS TIME THE
FRONT IS PROGGED TO DROP INTO IOWA AND NORTHERN ILLINOIS BY NEXT
TUESDAY BUT COULD BE CLOSE ENOUGH FOR A CONTINUED PCPN CHANCE FOR
PARTS OF CENTRAL WISCONSIN AND EAST CENTRAL WISCONSIN.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 107 PM CDT WED JUL 30 2014

NOT A GREAT DEAL OF CONFIDENCE IN THIS FORECAST. FOG DISSIPATED
AND CU DEVELOPED ACROSS MOST OF THE AREA BY MIDDAY...BUT CIGS AND
VSBYS WERE IN THE VFR CATEGORY AT 17Z. CHANCES FOR SHOWERS AND
THUNDERSTORMS PRESENT THE BIGGEST CHALLENGE. VISIBLE SATELLITE
IMAGERY SHOWED AN AREA OF CLOUDS...THAT APPEARED TO HAVE SOME
VERTICAL DEVELOPMENT...MOVING FROM JUST SOUTHEAST OF INL TO NEAR
DLH SINCE MID MORNING. THE 12Z INL SOUNDING WAS QUITE UNSTABLE
ABOVE A SURFACE INVERSION BUT...RADAR MOSAIC SHOWED LITTLE. HAVE
OPTED TO KEEP THE GENERAL IDEA OF AFTERNOON SHOWER AND
THUNDERSTORM DEVELOPMENT IN CONTINUED UPPER LEVEL CYCLONIC
FLOW...WITH CONVECTION DYING OFF IN THE EVENING. 12Z NAM/12Z
GFS/00Z ECMWF ALL SHOWED AREAS OF QPF IN THE STATE TODAY BUT
CONTINUED IT DURING THE NIGHT AND EVEN INTO THURSDAY. TOTALS WERE
GENERALLY LOW AND LOCATIONS DID NOT ALWAYS MATCH UP...SO HAVE
OPTED FOR THE SIMPLE PLAN FOR NOW. LIGHT WINDS AND DECREASING
CLOUDS TONIGHT WILL ALLOW AREAS OF FOG TO DEVELOP ONCE AGAIN.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM.....MG
LONG TERM......TDH
AVIATION.......MG