Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 220335
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
1035 PM CDT MON JUL 21 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 326 PM CDT MON JUL 21 2014

MAP ANALYSIS INDICATES UPPER TROPOSPHERIC RIDGING OVER THE WESTERN
TWO-THIRDS OF THE CONUS AND TROUGHING OVER THE EAST. A SUBTLE UPPER
TROPOSPHERIC PERTURBATION IS ALSO NOTED EMERGING FROM THE NORTHERN
HIGH PLAINS INTO THE NORTHERN PLAINS. ENHANCED UPPER TROPOSPHERIC
JET ENERGY EXTENDS FROM THE WESTERN CONUS...NORTHEAST INTO THE
NORTHERN PLAINS AND SOUTH CENTRAL CANADA...WITH UPPER TROPOSPHERIC
JET ENERGY REMAINING VERY WEAK OVER OUR AREA. AT THE SURFACE AN AREA
OF LOW BAROMETRIC PRESSURE EXISTS OVER THE NORTHERN PLAINS...WITH A
WEAK LOWER TROPOSPHERIC BAROCLINIC ZONE / TROUGH EXTENDING
SOUTH/SOUTHWEST FROM THE LOW INTO THE CENTRAL HIGH PLAINS. THE LOWER
TROPOSPHERIC WIND FIELD ACROSS OUR AREA REMAINS FROM THE SOUTHWEST
AS A RESULT.

GUIDANCE SUGGESTS THE AFOREMENTIONED SUBTLE UPPER TROPOSPHERIC
PERTURBATION WILL MOVE EAST/NORTHEAST THROUGH THE NEXT 24
HOURS...MOVING ACROSS THE NORTHERN PLAINS TONIGHT INTO THE DAY
TUESDAY. THE AREA OF LOW BAROMETRIC PRESSURE AT THE SURFACE IS
EXPECTED TO FOLLOW THE UPPER TROPOSPHERIC PERTURBATION BY MOVING
EAST/NORTHEAST THROUGH THE NEXT 24 HOURS AS WELL. THIS ALLOW THE
WEAK LOWER TROPOSPHERIC BAROCLINIC ZONE / TROUGH TO MOVE
EAST/SOUTHEAST THROUGH THE NEXT 24 HOURS...LIKELY CLEARING OUR CWA
AS A BAROCLINIC ZONE DURING THE DAY TUESDAY.

STARTING WITH THE HEAT THIS AFTERNOON AND EVENING...AFTERNOON
TEMPERATURE READINGS IN THE 90S...ALONG WITH SURFACE DEW POINT
READINGS IN THE 60S AND LOW 70S...ARE RESULTING IN HEAT INDEX
READINGS IN THE UPPER 90S TO LOWER 100S ACROSS MUCH OF THE REGION.
MORNING CLOUD COVER WILL LIKELY KEEP SURFACE TEMPERATURE READINGS
ACROSS OUR CWA FROM MEETING THEIR FULL POTENTIAL...BUT AFTERNOON
HEAT INDEX READINGS NEAR 103 AND PERHAPS MEETING 105 ARE STILL
EXPECTED AND AS A RESULT...WILL KEEP THE CURRENT HEAT ADVISORY GOING
THROUGH 01Z.

AN OVERALL LACK IN OMEGA SUGGESTS DRY CONDITIONS WILL BE OBSERVED
ACROSS MUCH OF THE AREA THIS AFTERNOON...TONIGHT...AND THROUGH MUCH
OF TUESDAY. THIS IS ALSO SUPPORTED BY THE FACT A STRONG CAPPING
INVERSION REMAINS IN PLACE ACROSS THE AREA AS WELL. ALL THAT BEING
SAID...A VERY WARM LOWER TROPOSPHERIC AIR MASS IS PROMOTING SURFACE
TEMPERATURE READINGS WELL INTO THE 90S THIS AFTERNOON. FORECAST
PROXIMITY SOUNDINGS FROM ACROSS THE CWA...PER THE NAM AND
OPERATIONAL GFS...SUGGEST THAT...ALTHOUGH THE OPPORTUNITY WILL BE
VERY LIMITED...CONVECTIVE TEMPERATURE READINGS COULD BE MET THUS
ALLOWING FOR A FEW ISOLATED SHOWERS AND THUNDERSTORMS ACROSS THE
AREA LATE THIS AFTERNOON INTO THIS EVENING. THIS IS A SOLUTION
SUPPORTED BY QPF FIELDS FROM THE NAM...EC AND SREF-MEAN...AS WELL AS
SIMULATED REFLECTIVITY FROM THE 4KM WRF-NMM AND HRRR. GIVEN ALL
THIS...FELT IT PRUDENT TO GO AHEAD WITH 20% POPS ACROSS MUCH OF THE
CWA 22-03Z. THE NAM...OPERATIONAL GFS AND EC ALL SUGGEST POTENTIAL
ENERGY OF 1000-3000J/KG WILL BE IN EXISTENCE SHOULD CONVECTION BE
REALIZED LATER TODAY. WITH THE TROPOSPHERE BEING AS WARM AS IT
IS...FIND IT HARD TO BELIEVE THAT LARGE HAIL WILL BE REALIZED...BUT
THE VERY WARM LOWER TROPOSPHERIC AIR MASS IS ALSO PROVIDING INVERTED
V-SOUNDINGS ACROSS MUCH OF THE AREA THUS SUGGESTING BRIEFLY STRONG
THUNDERSTORM WIND GUSTS COULD RESULT. GIVEN ALL THIS...WILL NOT
INTRODUCE ANY SEVERE WORDING INTO THE HWO AT THIS TIME...BUT WILL GO
AHEAD WITH ISOLATED THUNDERSTORMS AND BRIEF WIND GUSTS TO AROUND 50
MPH.

AS ALREADY MENTIONED...MUCH OF THE DAY ON TUESDAY SHOULD ALSO BE DRY
DUE TO AN OVERALL LACK IN OMEGA...BUT AS THE AFOREMENTIONED LOWER
TROPOSPHERIC BAROCLINIC ZONE CLEARS OUR CWA...LOCATIONS ACROSS OUR
SOUTHERN CWA ACROSS NORTH CENTRAL KANSAS COULD CERTAINLY SEE
ISOLATED CONVECTION IN THE VICINITY OF ENHANCED LOWER TROPOSPHERIC
CONVERGENCE AND LIFT ALONG THE BOUNDARY. THIS IS A SOLUTION
SUPPORTED BY QPF FIELDS FROM THE NAM...OPERATIONAL GFS...EC AND SREF-
MEAN. GIVEN THIS...WENT AHEAD WITH 20% POPS ACROSS PORTIONS OF NORTH
CENTRAL KANSAS TUESDAY AFTERNOON. POTENTIAL ENERGY ON THE ORDER OF
2000-3000J/KG ARE EXPECTED TO BE IN EXISTENCE DURING THE DAY TUESDAY
BUT AGAIN...GIVEN THE VERY WARM TROPOSPHERE SEVERE HAIL WILL BE HARD
TO COME BY...BUT WILL GO AHEAD AND MENTION BRIEF WIND GUSTS TO
AROUND 50 MPH IN THE HWO.

LITTLE TO NO CHANGE IN THE LOWER TROPOSPHERIC AIR MASS WILL PROMOTE
SIMILAR OVERNIGHT LOWS TONIGHT WHEN COMPARED TO EARLY THIS
MORNING...WITH LOWS IN THE 70S CURRENTLY FORECAST. ALTHOUGH A
SOMEWHAT COOLER LOWER TROPOSPHERIC AIR MASS WILL BEGIN WORKING INTO
THE CWA DURING THE DAY TUESDAY...LOCATIONS ACROSS OUR A
SOUTH/SOUTHEAST WILL NOT LIKELY OBSERVE MUCH OF ANY COOL DOWN WITH
TEMPERATURE READINGS NEAR 100 CURRENTLY FORECAST. LOCATIONS FARTHER
NORTHWEST ARE CURRENTLY EXPECTED TO REMAIN IN THE 90S.

FINALLY...THE COMBINATION OF A VERY WARM LOWER TROPOSPHERIC AIR
MASS...WORKING IN CONCERT WITH ENHANCED LOWER TROPOSPHERIC
MOISTURE...WILL LIKELY PROMOTE HEAT INDEX READINGS IN EXCESS OF 100
DEGREES TUESDAY AFTERNOON AND EVENING. WILL GO AHEAD AND CONTINUE
SUCH WORDING IN THE HWO AS A RESULT.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 326 PM CDT MON JUL 21 2014

THE BIG STORY WILL BE THE RELATIVE COOL DOWN ON
WEDNESDAY...NOTHING LIKE OUR COOL WEATHER OF LAST WEEK...BUT AT
LEAST A TEMPORARY BREAK FROM THE CURRENT HEAT. LOOKING AHEAD
THROUGH THE LONG TERM PERIOD...IT SEEMS LIKELY THAT MOST AREAS
WILL REMAIN DRY THROUGH THIS WEEKEND...WITH ONLY SLIGHT CHANCES OF
GENERALLY ISOLATED THUNDERSTORMS.

TUESDAY NIGHT THROUGH WEDNESDAY...COOLER AIR WILL FILTER FROM
NORTHEAST TO SOUTHWEST BEHIND THE COOL FRONT. THE 12Z GFS AND 18Z
NAM BOTH INDICATE THE POSSIBILITY OF ISOLATED THUNDERSTORMS ALONG
AND JUST BEHIND THE COOL FRONT. THE FOCUS OF THE NAM THUNDERSTORMS
IS IN CLOSER PROXIMITY TO THE FRONT WHILE THE GFS POTENTIAL WOULD
BE MORE FOR ELEVATED THUNDERSTORMS FURTHER NORTH AND MORE BEHIND
THE FRONT. OUR FORECAST WILL MORE CLOSELY FOLLOW THE NAM...WHICH
WILL CONFINE THE THUNDERSTORMS TUESDAY EVENING INTO TUESDAY NIGHT
ALONG THE FRONT OVER PRIMARILY NORTHERN KANSAS. THE LOW LEVEL JET
STRENGTH AND ORIENTATION DOES NOT SEEM FAVORABLE FOR ELEVATED
THUNDERSTORMS FURTHER NORTH OVER THE TRI CITIES. IT APPEARS THAT
ANY THUNDERSTORMS THAT DO FORM TUESDAY NIGHT SHOULD BE OUT OF THE
PICTURE BY WEDNESDAY MORNING. AGAIN...MOST LOCATIONS WILL LIKELY
BE DRY WITH THIS FRONTAL PASSAGE. WHAT EVERYONE SHOULD NOTICE IS
COOLER WEATHER. A LIGHT NORTHEAST SFC WIND AND COOLING HEIGHTS
ALOFT ON WEDNESDAY WILL LEAD TO ABOUT A 10 DEGREE COOL DOWN FROM
TUESDAY HIGHS. EXPECT WEDNESDAY HIGHS OVER SOUTH CENTRAL NEBRASKA
WILL BE IN THE 80S...WITH HIGHS AROUND 90 OVER NORTH CENTRAL
KANSAS.

THURSDAY THROUGH FRIDAY...THE COOL DOWN ON WEDNESDAY WILL BE SHORT
LIVED AS THE SFC WIND WILL TURN BACK TO SOUTHERLY ON THURSDAY AND
THEN SOUTHWESTERLY AHEAD OF A COOL FRONT ON FRIDAY. TEMPERATURES
AT 850 MB ALSO NOSE UPWARD ACCORDING TO FORECAST MODEL GUIDANCE.
THEREFORE...EXPECT HIGHS WILL ALSO RISE ON BOTH THURSDAY AND
FRIDAY WITH FRIDAY POSSIBLY THE WARMEST DAY OF THE EXTENDED
PERIOD...DEPENDING ON THE TIMING OF A COOL FRONT. A COOL FRONT IS
EXPECTED TO ENTER OUR FORECAST AREA FROM THE NORTHWEST FRIDAY
AFTERNOON...BUT INITIALLY IT MAY BE LITTLE MORE THAN A WIND SHIFT
LINE AS THE SLIGHTLY COOLER AIR WILL NOT WORK INTO THE AREA UNTIL
THE WEEKEND. THE NAM AND GFS INDICATE A SLIGHT CHANCE OF
THUNDERSTORMS ENTERING FROM WEST THURSDAY INTO THURSDAY
NIGHT...WHILE THE ECMWF IS DRY. THERE WILL BE A WEAK SHORTWAVE
TRACKING AROUND THE NORTHEAST SIDE OF THE UPPER RIDGE SO CAN NOT
RULE OUT THE POSSIBILITY OF ISOLATED THUNDERSTORMS.

SATURDAY THROUGH MONDAY...THE UPPER RIDGE WILL RETROGRADE BACK
INTO THE WESTERN CONUS PUTTING OUR AREA BACK UNDERNEATH NORTHWESTERLY
FLOW ALOFT. THIS IS PRETTY TYPICAL FOR THIS TIME OF YEAR AND HIGHS
SHOULD BE FAIRLY CLOSE TO NORMAL WHICH WOULD BE UPPER 80S TO LOWER
90S ACROSS OUR FORECAST AREA. RAIN CHANCES ARE NOT GOOD...BUT
CONFIDENCE IN THE PRECIPITATION FORECAST 5-7 DAYS OUT IN THIS KIND
OF PATTERN IS LOW.

&&

.AVIATION...(FOR THE 03Z TAFS THROUGH 03Z TUESDAY EVENING)
ISSUED AT 1011 PM CDT MON JUL 21 2014

THE BIGGEST ISSUE WILL BE A LOW-LEVEL JET DEVELOPING...POSSIBLY
PUTTING US CLOSE TO LOW-LEVEL WIND SHEAR OVERNIGHT...ESPECIALLY
FOR KGRI. THIS WILL HAVE TO BE CAREFULLY MONITORED WITH LATER
FORECASTS. VFR CONDITIONS ARE FORECAST.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&

$$

SHORT TERM...BRYANT
LONG TERM...WESELY
AVIATION...HEINLEIN



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